EPA-670/2-75-034
May 1975
Environmental Protection Technology Series
SPECIFICATIONS FOR
MATERIALS RECOVERED FROM
MUNICIPAL REFUSE
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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EPA-670/2-75-034
May 1975
SPECIFICATIONS FOR MATERIALS
RECOVERED PROM MUNICIPAL REFUSE
By
H. Alter and W. R. Reeves
The National Center for Resource Recovery, Inc.
Washington, D.C. 20036
Grant No. 801622
Program Element No. 1DB314
Project Officer
Carlton Wiles
Solid and Hazardous Waste Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center—Cincinnati has
reviewed this report and approved its publication. Approval
does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency,
nor does mention of trade names or commercial products constitute
endorsement or recommendation for use.
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FOREWORD
Man and his environment must be protected from the adverse
effects of pesticides, radiation, noise and other forms of
pollution, and the unwise management of solid waste. Efforts
to protect the environment require a focus that recognizes the
interplay between the components of our physical environment
—air, water, and land. The National Environmental Research
Centers provide this multidisciplinary focus through programs
engaged in
• studies on the effects of environmental contaminants
on man and the biosphere, and
• a search for ways to prevent contamination and to
recycle valuable resources.
This report presents a summary of research directed toward
development of specifications for defining the qualities of
materials separated and recovered from municipal solid waste for
subsequent sale and use. Specifications presented represent first
efforts towards providing potential users of recovered materials
with a basis for quality assurance.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
111
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ABSTRACT
Specifications presented in this report represent first
efforts to define uniform qualities of materials separated
from municipal solid waste in resource recovery processing
plants for subsequent sale and use. The establishment of
specifications adds value to outputs and promotes acceptance
by users as a result of providing a basis for quality assu-
rance. Recoverable materials investigated in this study are:
Folded newsprint and corrugated paper
Ferrous metals
Aluminum
Other nonferrous metals
Glass cullet
Inorganic fines
Mixed organics (for fuel)
Indications of possible contamination were obtained on a
limited scale by reviewing literature, visiting plants, and
coordinating with the activities of a companion research grant
which included processing pilot quantities of municipal solid
waste from several cities. The resulting target specifi-
cations were written as goals for plant design; the targets
seem achievable with existing technology. The likelihood
of these target specifications being accepted was checked by
reviewing them with officials of appropriate companies and
trade associations.
IV
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CONTENTS
Section Page
I Conclusions 1
II Recommendations 3
III Introduction 4
IV Method of Approach 11
V Materials Specifications 14
Paper 14
Steel 26
Aluminum 50
Other Nonferrous Metals 62
Glass 64
Inorganic Fines 76
VI References and Notes 94
VII Publications 105
VIII Appendices 106
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LIST OF TABLES
No. Page
1 Paper Specifications 17,18
2 Target Specification for Recovered News- 19
print
3 Target Specification for Recovered Old
Corrugated Boxes 20,23
4 Summary of Findings: (a) Ash and Organic
Solubles in Collected Newspapers; (b)
Microbiological Contamination 24,25
5 Tin Can Bundles - a Specification 28
6 Target Specification for Can Bundles -- 33,34
Ferrous Scrap for Steel Making
7 Target Specification — Cans for Pre- 35
cipitation Iron
8 Target Specification for Cans for Detinning 36
9 Target Specification for Ferrous Scrap for
Blast Furnace Feed 37
10 Reported Compositions — Three Classi-
fications of Ferrous Containers 41
11 1971 Seasonal Variations in Metal Mix,
Beer and Soft Drink Metal 42
12 Examples of Aluminum Items Found in
Municipal Waste 52,53
13 Chemical Composition Limits of Aluminum
Scrap, Target Specification — 1 56
14 Chemical Composition Limits of Aluminum
Scrap, Target Specification — 2 57,58
15 Chemical Analyses, Aluminum Hand-picked
from Municipal Refuse 61
vi
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LIST OF TABLES (continued)
No.
16 Target Specification for Other Non-
ferrous Metals 65
17 Guidelines for Gullet as a Direct 71
Replacement for In-plant Gullet
18 Target Specification for Gullet for Use
in Container Manufacture
19 Target Specification for Inorganic Fines 78
20 Average Fuel Composition — St. Louis
as Delivered to Union Electric Company,
1973, 1974 84
21 Properties of Coal as a Fuel grj
22 Norwalk Domestic Sampling Composition
Analysis 86
23 Target Specification for Refuse^Derived
Fuel 88
24 Properties of Refuse-Derived Fuel 90
25 Composition of Ash from Refuse-Derived
Fuel 92
vii
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PROLOGUE
Faults in Specifications*
The special fault which characterizes many specifications is
the attempt on the part of the one who draws the speci-
fication to make it a place to show how much he knows. We
have seen specifications which were apparently drawn with
no other thought in mind than to embody all the knowledge
the writer had on the subject. No discussion is needed
on this point. The folly of it is apparent to all.
Another fault is putting too many restrictions into the speci-
fication. According to our views, the fewer possible restric-
tions that a specification can contain, and at the same time
afford the necessary protection in regard to the quality of
the materials, the better the specification is. In some of
our specifications we have only one test; in others, perhaps
half a dozen; the effort, however, being always to have the
minimum number which will yield the product that is required.
A third fault in specifications is in making the limits too
severe. Some writers who draw specifications apparently
put themselves in a position of absolute antagonism to those
*The Life and Work of Charles Benjamin Dudley, STP 1,
American Society for Testing and Materials, Memorial
Volume, pp. 127 to 128. Mr. Dudley was President of
ASTM, 1902-1909.
vxn
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who are to make the material, and seem to have as a per-
manent thought in their minds to tie them down to the
extreme limit. The maximum that a single test piece shows,
the minimum of an objectionable constituent that may be
obtained by analysis, the extreme point in elongation that
by chance some good and exceptional sample gives, are made
to represent the total output of the works. It is, perhaps,
needless to say that such extreme figures are the worst
possible mistake in making specifications.
IX
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SECTION I
CONCLUSIONS
Tentative or target specifications for materials offered for
sale by resource recovery plants must be agreed to between
processor and buyers in advance of start-up of such plants.
The targets result from technology likely to be employed
and the needs and requirements of user industries, i.e., the
buyers of the recovered products. Separated materials are
likely to be accepted for purchase by users only if the re-
covery processes are chosen and operated to meet the speci-
fication for reuse along with regular feed-stocks into
existing processes.
The specifications for many of the recovered materials must
contain considerable detail, even limits of chemical com-
position. This is a more exacting requirement than practiced
currently in the commerce of secondary materials. The more
exacting requirements are detailed to assure buyer and seller
alike that the recovered materials did not become contaminated
by contact with mixed, municipal solid waste or by the mech-
anical and chemical processing required to separate the
materials from this waste. Unfortunately, it is not always
possible to provide this detail and, in many instances, the
specification is a qualitative description only.
The target specifications are recommended subject to the
consensus, and adoption by potential producers, users and
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cognizant professional and trade associations. Before such
adoption the target specifications presented here may serve
as a starting point for negotiations for the sale of re-
covered fractions from resource recovery plants.
Additional activities are required to further refine and
finally to have adopted specifications for materials (and
fuel or energy) recovered from municipal solid waste. The
activities associated with preparation of this report in-
cluded assistance in the formation of Committee E-38 of the
American Society for Testing and Materials (ASTM). It is
expected that this committee will continue to work toward
establishment of final specifications in the field.
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SECTION II
RECOMMENDATIONS
This report contains recommended target specifications for
materials apt to be recovered from mixed, municipal solid
waste. They were developed by consideration of user technology
and needs, and through negotiation with user industries.
As such, they should be considered the first step toward
acceptable specifications for negotiating the sale of re-
covered fractions from any proposed resource recovery plant.
Final adoption must await full consideration by the users and
producers of the recovered materials and by cognizant pro-
fessional and trade associations.
Wherever possible, the specifications were tested against
analyses of fractions from municipal solid waste. The
fractions were separated and selected so as to represent, as
nearly as possible, the state of the art of separation pro-
cesses. Because at the present time there are few full-scale
resource recovery plants in operation, it was not possible
to test the specifications further. As such, it is recom-
mended that they be considered subject to further test and
analysis as plants are built and put on-stream.
It is recommended that refinements of specifications for
recovered materials be coordinated with cognizant standards
setting organizations such as ASTM, NARI, ISIS and ANSI.
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SECTION III
INTRODUCTION
A specification for a material is the designation of particu-
lars of form and/or composition as the basis for acceptance
or rejection, for sale or use. The specifications for a raw
or processed material may also be used to determine price.
Material specifications are a normal part of commerce and an
important tool for technological processing industries.
Specifications are equally useful in the commerce of both
virgin and secondary products. Organizations such as the
National Association of Recycling Industries (1) and their
commodity division, the Paper Stock Institute (2), have
established material descriptions, specifications, and grades
of secondary materials (3). These also form the bases for
commodity quotations in the scrap market (4).
There is great, recent interest in implementing resource re-
covery from municipal waste. Various processes have been
proposed to recover, for resale and reuse, a variety of
metals, glass, and paper (5). It was the objective of the
work reported here to establish specifications for the
materials apt to be recovered from such processes to facili-
tate their purchase by user industries. Several general
criteria or guidelines were used in formulating the speci-
fications :
(a) Recovered materials should be processed to be sold in
form and cleanliness that will require minimum per-
turbation to user industries (6).
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(b) The specification should permit forms easily produced,
shipped and handled.
(c) The specification should be capable of being tested
using existing (and hopefully simple) analytical
techniques.
(d) The specification should be within the state of the
art of known recovery systems and processes.
(e) The specification should be as quantitative as possi-
ble, avoiding non-specific terms, such as "clean".
(f) The specifications developed are targets, or "first
generation", subject to revision with experience, with
future involvement of interested parties, and by
voluntary consensus. (These are normal steps in the
evolution of any specifications).
In developing specifications, no constraints were imposed
as to the processing technology to be employed. It was con-
sidered that any of the recovery systems described to date
(5) might be employed to meet specifications, by themselves
or with the addition of some few simple processing steps.
The materials considered were newsprint, old corrugated
boxes, steel, glass, aluminum, other non-ferrous metals,
inorganic fines and a mixture of organic materials suitable
as supplemental fuel for direct firing with coal or oil to
raise steam.
The only paper products considered to be recoverable were
portions of the old corrugated boxes and some newspaper.
It is believed that if newspaper is prebundled by the
householders, it can be picked from the refuse prior to
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mechanical processing (7). The remainder of the paper, that
mixed with food and garden waste, and portions of composite
packaging, are unlikely inputs for modern, high-speed paper-
making processes. Some of the reasons for this are dis-
cussed in the sections following dealing with paper
specifications.
One of the outputs of any materials recovery process using
mixed, municipal refuse as the feed stock is a complex mix-
ture of organic materials consisting of the mixed papers,
food wastes, garden wastes, plastics, etc. Possible al-
ternative uses for this mixture include compost, feedstock
for pyrolysis, and as a refuse-derived fuel or RDF. No
specifications for compost were considered because it is
unlikely this process will gain widespread acceptance in the
United States (8). Similarly, no specifications were con-
sidered for feedstock for pyrolysis; the methods described
to date seem designed to accept a wide variety of feed-
stocks, more like a disposal unit (9). A possible speci-
fication for refuse-derived fuel for direct firing (10)
was considered and is included.
Not everything in municipal waste has a value or high enough
value to make recovery worthwhile. Therefore, there will
always be a fraction for disposal (11). No specifications
for waste products or for disposal practices were considered.
The specifications described here are designed to serve as
bases for acceptance testing of the recovered materials. As
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such, they should be independent of the resource recovery
technology employed to separate them. However, as an
example of technology which might be used, Figure 1 shows a
series of steps which could constitute a material recovery
process. Waste products and recovered products are in-
dicated.
Statement of the target specifications does not guarantee
buyers will accept the specification. In other words, re-
covery to specification does not guarantee saleability. The
general considerations of the background and structure of the
markets for the recovered materials are covered adequately
elsewhere (12).
As a broad generalization and simplification, specifications
for materials may be categorized as describing performance,
origin, or composition. Performance specifications are used
when the material must meet mechanical or chemical criteria,
such as strength, durability, weathering, etc. This type
of specification is more suited to finished products? e.g.,
to iron pipe or steel girders than to the base material,
such as iron or steel. Hence, performance specifications
are not applicable to products recovered from municipal
refuse.
Origin specifications have been used to advantage by the
secondary materials industry for longer than the sixty years
since the founding of what is now called the National
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Picked paper
K
00
Ferrous fraction
Feed
Mixed municipal
solid wastes
Shredder
Organic fraction
Potential fuel
Ferrous fraction
1st Heavy media
separator
Sinks
Magnetic drum
separator
2nd Heavy media
separator
Other nonferrous
Glass
Clear glass
Organics
Fine glass
Floats
Organics
[Floats (glass and aluminum)
Coarse 1
Roll crusher
Screen
H
Electrostatic
separator
Color sorter
Green and amber glass
Aluminum
Figure 1. Processing scheme for separating
materials from mixed refuse
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Association of Recycling Industries, the cognizant trade
association. Origin specifications are illustrated by de-
signations such as "Genuine Babbitt-Lined Brass Bushings,"
"New Zinc Clippings," "Over-Issue News." The origin speci-
fication is not only a description of the material, but
also often indicates limits of principal contaminants.
This type of specification is essential for home and prompt
scrap. It is also useful for materials recovered from
municipal waste under certain circumstances, such as from
voluntary recycling, hand separation, and sometimes, rejects
from production of consumer items. This is reflected in the
published specifications titled "Shredded Tin Cans," "New
Aluminum Can Stock," and "Old Can Stock." (See Appendix A
for examples of such currently accepted scrap specifications.)
The published specification for "Incinerator Bundles"
(Appendix A) describes the origin of a waste material from
an established disposal process.
Origin specifications will not always be useful for products
recovered from municipal refuse by combinations of mechanical
and chemical processing. The reason for this is that the
processing techniques are varied; many have been proposed and
new ones are likely to be developed. At the present time,
many new concepts for processes are untried. Thus, there
is no large body of experience to make origin type speci-
fications meaningful. Separation and recovery processes
which have been proposed include steps which may not achieve
complete separation and/or which may introduce a contaminant.
An example of the latter is heavy media separation of
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aluminum which may contaminate the product with iron and/or
silicon. (This point is discussed later.) The existing
origin type specifications do not make allowance for these
circumstances and, therefore, cannot be used to assure quality
and purity to buyers.
10
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SECTION IV
METHOD OF APPROACH
The approach to the research reported here was to identify
existing specifications for materials likely to be recovered
from mixed municipal refuse, ascertain their usefulness by
comparision with user (buyer) needs, and identify the con-
taminants likely to be found in the separated materials.
The results of these activities were target specifications
combining origin characteristics with chemical compositional
limits which could be tolerated by the user industries.
NCRR had background information and knowledge of the com-
position of municipal solid waste (MSW) prior to starting this
project. Literature searches had been made to review attempts
at separating useful products from MSW. Visits were made
to sites where separation equipment was being used, fab-
ricated, or designed. Additionally, NCRR had performed
several preliminary sampling studies. With this preparation,
a previously proposed flow sheet (7) (13) , shown in Figure
1, was devised to incorporate steps needed for separating
a representative spectrum of materials which had the
greatest apparent economic value per ton of MSW feed. This
flow sheet is only an example of the way known unit opera-
tions could be combined to process municipal solid waste
for resource recovery. The objective was to keep the
concept simple and incorporate off-the-shelf processing
equipment wherever possible (7).
11
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Having identified the separation products of interest, NCRR
personnel started a program of developing specifications by
reviewing the technology of industries which might use the
outputs. Concurrently, visits were made to companies which
were potential purchasers of the recovered materials to
discuss existing practices, requirements, and sensitivities
to contaminants.
Some early efforts at writing standards based on first
findings were submitted to appropriate organizations which
have interest in specifications for materials. While
little positive affirmation was received because of lack
of supporting data, i.e., no operating separation plant,
most organizations contacted expressed support for the
specifications program.
Thus, while recommended specifications presented in this
report are, at best, a start toward establishing accept-
ability of recovered products, the interest generated by
this study should carry forward into future years. Hope-
fully, this effort will shorten the time which otherwise
v/ould have been required to design materials recovery
plants and find stable viable markets for their outputs.
The research and related activities described here helped
generate broad interest in specifications for materials
likely to be recovered from MSW. One related result of
this new interest was the founding of a new committee
12
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within the American Society for Testing and Materials
(ASTM), designated E-38, Resource Recovery. Another re-
lated result was the National Materials Conservation
Symposium: I. Resource Recovery and Utilization, held
April 29 to May 1, 1974, sponsored by the Environmental
Protection Agency, the Bureau of Mines, the National Bureau
of Standards, ASTM, and the National Center for Resource
Recovery (14).
13
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SECTION V
MATERIALS SPECIFICATIONS
In this section, each material likely to be recovered from
mixed municipal solid waste is discussed from the stand-
point of:
background, including user requirements
. recommended target specification(s)
analyses which support the choice of speci-
fication
The materials discussed are newsprint, old corrugated boxes,
steel, aluminum, other nonferrous metals, glass, inorganic
fines, and a refuse-derived fuel.
PAPER
Background
Shredding of municipal waste is almost always the first step
in refuse processing for resource recovery (15) , whether
for wet or dry processing and for both materials and energy
recovery systems (5). It was postulated (7) that clean
newspaper and clean old corrugated boxes could be picked
from the shredder feed conveyor provided householders (i.e.,
the disposer) bundled these materials before they were
collected in a packer truck. Alternatively, the paper
could be separately collected on the packer truck (16).
The likely form of such recovered materials was compared
to existing standards and specifications for secondary
paper (2); the closest match between the standard grade
14
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and the expected form of the recovered newspaper occurs
when the paper meets the requirements for "No. 1 News."
Similarly, recovered corrugated paper board could match
the requirements for "Corrugated Containers." Both
are standard grades of the Paper Stock'Institute of
America (2).
The published grades for No. 1 News and Corrugated Con-
tainers are listed in Table 1. A grade identifies and
describes a material in a way such that the buyer knows
the types of fibers and the condition of the material
on receipt. In the secondary paper market it also implies
the source of origin of material.
The specifications also list maximum permitted contents
for prohibitive materials and outthrows. A prohibitive
material is any included in a bale which if found in
greater than the specified level would damage the paper-
making equipment and/or destroy the quality of the final
product. Examples are latex adhesives, magnetic inks,
plastics, or asphaltic papers. Outthrows are contaminants
which make the product unsuitable for consumption at the
grade specified. Outthrows usually consist of materials
which are compatible with the paper-making process but if
found in amounts greater than the specified level will
significantly degrade the quality of the final product.
Examples are cloth bindings, chipboard, string bindings,
and glassine. The effect of these materials, and
pernicious contraries, have been discussed (17).
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The Paper Stock Institute lists 24 grade definitions, most
not applicable to paper in municipal solid waste, but
several similar to No. 1 News. These several grades cover
mixes consisting mostly of newspaper: Super News, Special
News De-Ink Quality, and Over-Issue Mews. The specifica-
tions for these are also listed in Table 1 as an illustra-
tion of more exacting requirements for lower quantities
of prohibited materials and outthrows. For example, none
of either are permitted for the Over-Issue News category.
It seems unlikely that householders could be educated to
make their bundles completely free of outthrows, or foreign
materials, and prohibitive materials, such as nylon hose
or neckties (18). The No. 1 News grade permits more leeway;
it should be easier to achieve at the expense of a lower
selling price.
Other grades of paper are based on plant wastes or office
wastes. The former are homogeneous such as envelope cuttings;
the latter have limits on the amount of groundwood pulp
permitted (2). These grades are not applicable to house-
hold wastes.
The possibility exists that bundled paper and corrugated
picked from packer truck refuse (say from the feed con-
veyor belt to a shredder) can accumulate dirt, grease, or
similar contaminants from the refuse. These possibilities
are not provided for in the existing PSI specifications
(2) but must be part of any specification for paper to be
16
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Table 1
Illustrative Paper Specifications
#1 NEWS
Consists of newspaper packed in bales of not less than 54
inches in length, containing less than 5% of other papers.
Prohibitive materials may not exceed 1/2 of 1%
Total Outthrows may not exceed 2%
SUPER NEWS
Consists of sorted fresh newspapers, not sunburned, packed
in bales of not less than 60 inches in length, free from
papers other than news and containing not more than the
normal percentage of rotogravure and colored sections.
Prohibitive materials None permitted
Total Outthrows may not exceed 2%
SPECIAL NEWS DE-INK QUALITY
Consists of sorted, fresh, dry newspapers, not sunburned.
Packed in bales not less than 60 inches in length, free
from magazines, white blank, pressroom over-issues, and
paper other than news, and containing not more than the
normal percentage of rotogravure and colored sections.
This packing must be free from tar.
Prohibitive materials None permitted
Total Outthrows 1/4 of 1%
OVER-ISSUE NEWS
Consists of unused over-run regular newspapers printed
on newsprint, baled or securely tied in bundles, and
shall contain not more than the normal percentage of
rotogravure and colored sections.
Prohibitive materials None permitted
Total Outthrows None permitted
Source: Paper Stock Standards and Practices Circular,
Paper Stock Institute of America, August, 1972.
17
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recovered from household waste. Dirt, grease, and similar
contamination can be monitored by determining the amount
of ash, water and solvent extractable materials in the
paper by standard methods (19) (20).
Recommended Specifications
The specification for separately collected old newspapers
and corrugated materials have been published (2). Tables
2 and 3 list the recommended target specifications for
paper and corrugated materials, respectively, for materials
recovered after being comingled with mixed waste in a
packer truck. The bases for the values listed for pro-
hibitive materials and outthrows are the PSI specifications
(2). The rationale for values of ash and extractables will
follow. At this time, no odor specification is included.
It is possible that newspaper and corrugated mixed with re-
fuse will pick-up undesirable odors. If the recovered
paper is to be used for any products where this is important,
additional points will have to be added to the specification
(21). At this time, it is not recommended that the re-
covered paper or corrugated be used as furnish for chipboard
for food packaging or any other product which may be sensi-
tive to odor, taste, or possible contamination with ex-
traneous metal ions. More work is needed to establish a
basis for setting specifications on these points. The
target specifications in Tables 2 and 3 are not meant to
preclude separate collection of these materials (16) and
sale subject to existing specifications (2) or others.
18
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Table 2
Target Specification for Recovered Newsprint
Grade Title:
Description:
Packing:
Moisture:
Prohibitive
Materials:
Outthrows:
Water Solubles:
Organic Solubles
Ash:
Recovered News (equivalent grades—
Folded News, Regular News, Ordinary
Folded News, No. 1 News)
Consists of folded newspaper including
the normal percentage of rotogravure
and colored sections
Packed in bales of standard dimensions,
not less than 54 inches long, approxi-
mately 1,000 to 1,500 pounds per
bale.
Packed air dry
Less than 1/2 percent
Less than 2 percent
Less than 2 percent of the acceptable
paper (Note a)
Less than 2% of the acceptable paper
(Note b)
Less than 1% of the acceptable paper
(Note c)
Note a: Determined by ASTM D-1162 or equivalent
Note b: Determined by ASTM D-1804 or equivalent
Note c: Determined by ASTM D- 586 or equivalent
19
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Table 3
Target Specification for Recovered Old Corrugated Boxes
Grade Title:
Description
Packing:
Moisture:
Prohibitive
Materials:
Outthrows:
Water Solubles:
Organic Solubles:
Ash:
Recovered Old Corrugated Boxes
Consists of used corrugated con-
tainers having liners of jute or kraft,
Packed in bales of standard dimensions
not less than 54 inches long; approxi-
mately 1,000 to 1,500 pounds each
Packed air dry
Less than 1 percent
Less than 5 percent
Less than 2 percent of the acceptable
corrugated (Note a)
Less than 2 percent of the acceptable
corrugated (Note b)
Less than 1% of the acceptable corru-
gated (Note c)
Note a: Determined by ASTM D-1162 or equivalent
Note b: Determined by ASTM D-1804 or equivalent
Note c: Determined by ASTM D- 586 or equivalent
20
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Analyses
The target specifications in Tables 2 and 3 are based on
the premise that the bundled newsprint and corrugated
materials collected with other household waste, and de-
livered in a packer truck, could be recovered in a way
to have the same properties as if collected separately.
However, there is a possibility that mixing the paper and
corrugated with putrescibles, wet garbage, and the other
various contaminants in the truck, could cause deteriora-
tion of the fibers and introduce excessive dirt and pro-
hibitive materials.
The above premise was tested experimentally. The City of
Rockville, Maryland, has a separate newspaper collection,
monthly. With their cooperation (22) , prebundled newspaper
at curbside was collected in the packer truck along with
the regular semi-weekly refuse collection for that route.
This was done twice—on a dry day and on a day following
heavy rains. At the same time the paper was collected
with the refuse this way, some bundles were picked from
the curb at random, packed in heavy walled polyethylene
bags, and set aside as controls, representing separate
collection. After the crew completed their route, the
truck was tipped separate from the regular collections
(22) where the prebundled newspaper was picked with eare
to avoid the obviously dirty paper. No attempt was made
to be highly selective in choosing clean paper. Samples
were bagged; the remainder on one particular day was baled
at a local scrap yard (23). The baled material (ca. 1,300
Ibs.) was sent to a potential user, operating a roofing
21
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felt mill; the bagged samples were analyzed in the lab-
oratory. The report from the user was that the paper was
"good stuff" (24).
The bagged samples were analyzed at the Gillette Research
Institute, Rockville, Maryland (25). Analyses were made
for moisture ash, solvent, and water extractables, tear
and tensile strength (all using ASTM methods, ref. 19) and
bacterial and fungal contamination. The paper collected
in the packer truck mixed with refuse was compared to the
separately collected newspaper and to unused newspaper
stock as controls. The results are summarized in Tables
4a and 4b; details are given elsewhere (26) . These results
are the basis for the values for ash content and extrac-
tables in the target specification for No. 1 News. (No
laboratory work was done using recovered corrugated but
presumably the values could be chosen based on values for
suitable controls.)
The laboratory examination of the.paper showed the samples
which were collected separately to be about the same as
those collected in the packer truck judged from mechanical
strength (as a measure of severe physical deterioration)
and contamination — with one exception.
The count of cellulolytic microorganisms (bacteria and
molds, but principally the latter) was significantly higher
for one sample collected in the packer truck, but not the
22
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other, compared to controls. It must be pointed out,
however, these organisms are aerobic and require moisture
for growth; cellulolytic microorganisms are generally
slow growing and slow acting. It is expected that in a
paper bale, and especially at less than 10 percent
moisture, these organisms will have no significant effect
on the paper (26).
23
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KJ
Table 4a
Summary of Findings—Ash, Organic Solubles,
And Water Solubles in Collected Newspapers
A B C D E F
Property curbside curbside comingled unprinted curbside, comingled
(method) fresh,dry overnight, after dry newsprint wet after wet
dry day , day
Ash, %
(ASTM D586)
Mean 0.51 0.38 1.12 0.53 0.45 0.50
Range 0.49-0.52 0.33-0.42 1.09-1.14 0.51-0.55 0.44-0.47 0.48-0.53
Org. Soluble, %
(ASTM D1804)
Mean 1.85 1.84 2.49 0.32 1.53 1.58
Range 1.84-1.86 1.83-1.85 - - 1.46-1.59 1.57-1.59
Water Soluble, %
(ASTM D1162)
Mean 1.0 1.0 0.6 0.9 1.75 1.25
Range 0.90-1.15 0.71-1.24 0.54-0.67 0.86-0.90 1.53-1.96 1.24-1.25
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Table 4b
MICROBIOLOGICAL CONTENT OF WET AND DRY NEWSPAPER (ORGANISMS/CM2)
B C C D E E F
Wet Damp
Total Microorganisms 2.75 4.50 520 1425 1.25 178 1.00 0.50
Bacterial Spores 1.25 1.75 6.75 10.8 0.25 2.50 0 0
Total "Cellulolytic"
Microorganisms 1.50 2.75 513 1414 1.00 175 1.00 0.50
Molds 0.25 0 13.3 18.0 0 158 0.50 0
"Cellulolytic"
Bacteria 1.25 2.75 500 1396 1.00 17.5 0.50 0.50
(a) For identification of samples A-F, see Table 4a.
(b) This particular portion of sample "C" was intentionally hand-picked
as obviously contaminated with household refuse.
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STEEL
Background
The preponderant form of steel in mixed municipal refuse
(mostly household sources) is cans - both tin plate and
tin free steel (27) 028). A study (29) of iron and steel
in MSW showed that cans (and related container steel) made
up approximately 90 percent of the sample (500 Ibs.) in one
city and 94.6 percent of the sample (26 samples, average
weight 13.9 Ibs.) in another. The balance of the ferrous
metal consisted of small miscellaneous items as hardware,
metal castings, and nondescript bits of metal, most of
which passed through a 1/2-inch screen. (Shredded can
pieces were largely in excess of 1/2-inch in size). Some
old bicycle and auto parts could also be recognized.
Given the apparent importance of steel containers in the
magnetically separated component, it is necessary in writing
specifications to focus on this portion.
There are several possible uses (3)(12) for recovered
steel cans. The following were identified:
substitute for iron ore as a charge to blast furnaces
charge for steelmaking in the open hearth, BOF,
Q-BOP furnaces or electric furnace
remelt in electric furnace for continuous casting
detinning
raw material for ferroalloy production
26
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precipitation iron
cast steel
Some requirements for each use, leading to specifications,
are discussed. The general principles of each process
are described in standard texts (30).
What is termed steel here is really a mixture of several
iron containing metals to be recovered from municipal
solid waste. Perhaps more accurately, the mixture of
alloys should be termed "magnetic metals." Often, these
are referred to as ferrous metals. It must be pointed
out that not all ferrous (iron-containing) metals are
magnetic.
Table 5 is the specification for Can Bundles issued by
U.S. Steel Corporation. It is qualitative, perhaps too
much so, but follows the same format for scrap as used by
the industry for years (3). (See Appendix A for examples.)
Apparently, the industry has not yet found a need
for more quantitative specifications, in spite of the
inherent weakness of any qualitative specification.
Also, there are no generally accepted methods of statisti-
cally sampling large shipments of scrap steel so as to
quantify the amount of contaminants.
Following industry examples (Appendix A), target speci-
fications were written including qualitative descriptive
27
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Table 5
Tin Can Bundles
Tin Coated Scrap Steel Cans, hydraulically compressed
to charging box size not over 24" x 24" x 60" and
weighing not less than 75# per cu. ft. Tin cans must
be clean and free of all liquids and solids prior to
baling. Tin free steel beverage cans with or without
aluminum tops may be included. Must be free of aluminum
cans, loose tin plate and terne plate scrap in any form,
dirt, garbage, nonferrous metals (except those used in
can construction), plastics, vinyls in any form, and
other non-metallics of any kind.
Source: United States Steel Corporation
Purchasing Division
August 25, 1972
28
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terms. In some instances, the specification could be
related to alloy compositions of can stock and allowing
for contaminants and physical form which could assist
reuse in the applications listed above.
The basis for target specifications are conversations
with various companies and the references cited. Among
those contacted were major copper ore processors. Generally,
like the steel industry, they do not purchase steel
scrap to a quantitative specification. Like many other
users of secondary materials, their practice is to pur-
chase from dealers whom they know have shipped usable
material in the past.
Recommended Specifications
It has been proposed that magnetic metals may be divided
into heavy and light fractions using an air knife (31)
or the entire portion may be shredded to minus two inch
size, magnetically separated a second time, and shipped as
a heterogeneous, loose mass (32). If the former, the heavy
magnetic metals are expected to consist of a nondescript
mixture of bar, castings, nuts and bolts, nails, rod,
pipe, miscellaneous hardware, etc. Most pieces,are ex-
pected to be less than 1 inch thick; generally, this
fraction may also contain shredded portions of appliances.
Smallest pieces are expected to be 1/2 inch — largest 4
or more inches in size — from the type of shredders used
29
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for municipal refuse. Some pieces may contain small
portions of bonded nonferrous metals, such as fasteners.
The content of alloying and tramp elements is expected
to total less than 2 percent by weight, including carbon,
based on the analyses presented in the section following.
The heavy, miscellaneous steel fraction may best be
shipped loose. It's bulk density can not be predicted
because of the heterogeneous nature of the mix.
The light fraction of a split will consist chiefly of
cans, the principal source of ferrous metal in municipal
solid waste. The cans must be reasonably clean and free
of liquids and solids prior to baling so that bales, when
sampled, will conform to the target specifications listed
in Table 6. This specification is an attempt to
quantify the specification of Table 5 to avoid non-
specific terms. It must be pointed out that the numbers,
specifically for non-metallic impurities, are based on
a judgement of the capabilities of resource recovery
equipment and are subject to revision as a quantitative
basis is established. Also, the quantitative nature of
the target specification in Table 6 is very much different
from accepted industry practice (See Appendix A).
Steel cans prepared for sale to the copper industry for
precipitation iron are described in the target specifi-
cation in Table 7. Note that it is important for the
30
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material to be of fairly uniform thinness such that the
precipitation reaction is rapid and nearly complete for
each batch. Baled cans are unacceptable for use in the
copper cementation process because surface exposure is
too limited to permit reasonable reaction time. There
is no known way of quantifying these requirements. This
specification (and others) remain qualitative.
A third possible specification for a light ferrous fraction
applies to cans suitable for detinning (See Table 8).
Such material must be relatively free of organic materials
which unnecessarily consume the detinning solution. Un-
like cans prepared for use as precipitation steel, those
tin cans destined for detinning cannot be incinerated to
remove organic contaminants; incineration causes the tin
to diffuse into and alloy with the base steel (33) and thus
be unrecoverable. Aluminum also unnecessarily consumes
the caustic solutions used for detinning so is an unwanted
contaminant. The content or organic materials stated in
Table 8 is based on measurements (unpublished) of the
organic content of the ferrous fraction processed by
shredding and air classification prior to removal with a
magnet.
Another method of preparing the magnetic metals from mixed,
municipal waste for market, is to remove the shredded cans
from the mix with a magnet, re-shred in a particular
type of device to ball the steel in small pieces of high
31
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bulk density, and again magnetically separate so as to
leave behind aluminum ends and dirt (32). The material
prepared this way appears suitable as feedstock for
blast furnaces. Table 9 is a target specification for
such material, based on reference (32).
Analyses
The light fraction of ferrous metals in municipal solid
waste will consist chiefly of cans, both tin plate and
tin free steel. These container stocks are made from
cold rolled plate. Tin plate contains approximately
7-1/2 pounds of tin per ton (33). The tin free steel has
a surface treatment of an ultra-thin layer of chrominum
oxide (or similar material) to retard corrosion (34).
The side seams are either welded or soldered with a low
tin, lead solder (35). The cold rolled steel body stock
may be one of several alloys, but has the general des-
cription (36) :
Composition of Steel for Tin Plate - MR Grade
Element Content
C 0.12% max.
P 0.02% max.
Cu 0.20% max.
Mn 0.20% to 0.60%
Si 0.01% max.
S 0.05% max.
In addition to the cold rolled steel can body stock, other
materials used in can making are organic components
(described later), lead and tin in solder, and aluminum.
32
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Table 6
Target Specification for Can Bundles
Ferrous Scrap for Steel Making
Material: Predominantly steel cans,
magnetically separated from
shredded municipal solid waste
prior to incineration.
Alloy Composition: All magnetic material, com-
position essentially similar to
cold rolled steel used for can
body stock but containing up
to 4% aluminum that is normally
used in can construction (notes
a and b).
Non-metallics: Less than 1% except for materials
normally used in can construction
Bale Size: Specified by user (note c).
Bale Density: 75 lbs./cu. ft., nominal, minimum
Cleanliness: Free of organic materials and
putrecibles so as not to present
a health hazard.
Notes:
(a) Based on 31% of all cans produced as tin free steel and
approximately 92% of these bi-metallic (aluminum ends). The
weight of aluminum is 11.2% of the can weight. From these
data, 3.2% aluminum in the bundles is a reasonable ex-
pectation. The 4.0% aluminum content listed above allows
for seasonal variation, such as in the summer, when it is
likely there will be more bi-metal beverage cans in the
refuse.
33
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Notes:
(b) Bundles must be free of all aluminum cans, loose
tin plate, terne plate scrap in any form and other
principal pieces of non-iron scrap.
(c) The cans must be free of draining liquids when baled,
34
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Table 7
Target Specification — Cans for Precipitation Iron
Shredded and crumpled cans, not folded .on themselves
(all magnetic material), loose packed density of 30 Ibs./
cu. ft. maximum.
Scrap should consist of mostly cans so as to be of near
uniform gauge and of maximum surface area. If not shredded
to this specification, the cans may be prepared for
shipment to a dealer and processor of scrap for the copper
industry. If this is the case, the cans must be clean,
free of heavy plate or wire, and shredded to a density
to permit a 40,000 Ibs./railroad car minimum shipment.
If prepared for shipment to a dealer-processor, the cans
may be first incinerated to remove lacquers and organic
contaminants but not enough to cause oxidation and metal
loss to the point of flaking and loss in strength and
integrity of the individual cans or to be detrimental to
strapless baling.
35
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Table 8
Target Specification for Cans for Detinning
Composition: All magnetic can material, not
incinerated
Form: Loose flowing, whole cans or
shredded to maximum surface
area, free flowing (note a).
Rejects: Balled or convoluted material
blocking access of detinning
solution (note a)
Organic Content: Maximum 5%. Content may be
used to determine price.
Aluminum Content: Only from a normal mix bi-
metallic cans, less than 4%.
Content may be used to de-
termine price (note b).
Notes:
(a) These are qualitative descriptions. Access of de-
tinning solution, and permeability of cans to this
solution, are qualitative judgements. Conceivably, this
property could be quantified as the permeability (or
drainage) of a specified volume of liquid through a
column of cans of specified envelope dimensions. A
specification for permeability can follow suitable ex-
perimentation and may have specifying this property may
be more advantageous than specifying bulk density. The
two are related but achieving a particular bulk density
does not insure proper permeability.
(b) See Note a, Table 6.
36
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Table 9
Target Specification for Ferrous
Scrap for Blast Furnace Feed
Alloy Composition:
Plastics:
Dirt:
Non-metallics:
Physical Description:
Piece Size:
Bulk Density:
Similar to MR Grade cold
rolled steel used for can
stock but containing up to
4 percent aluminum and up
to 20 percent assorted
ferrous alloys (note a).
Visibly free except for
plastics normally used in
can construction
Less than 3% less than 10
mesh (note a).
Less than 1 percent (note a)
Loose free-flowing pieces —
balled except for mis-
cellaneous lengths of wire.
95% by weight through a 1 1/2-
inch screen.
In excess of 75 Ibs. per
cubic foot.
Note:
(a) The exact figures in these portions of the specifi-
cation are subject to revision with experience. All are
expected to be lowered on further analyses of material
prepared as balled ferrous scrap for blast furnace feed.
37
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Steel cans for beer and soft drinks frequently are made
with aluminum ends of 5182 alloy so as to incorporate
a tear-tab of 5082 alloy (37). The likely chemical
composition of recovered steel cans may be derived from
several literature sources (38)(39)(40).
Steel Other
Beverage Steel Total for
Composition Cans Cans Composite
Organic Coating
or lining .64 1.19 1.83
Aluminum 3.44 0.00 3.44
Lead .49 1.20 1.69
Tin .11 0.31 0.42
Steel 30.32 62.30 92.62
The content of aluminum is based on the premise that:
(a) approximately 95 percent of beverage cans have
aluminum ends, (b) soft drink cans and malt beverage
containers comprise about 35 percent of total can ship-
ments in the United States (40) , (c) of the beverage
cans, about 24 percent are made of tin free steel with
aluminum ends, 72 percent of tin plate with aluminum ends,
and approximately 4 percent made completely of tin plate
(41).
The estimated composition (above) is consistent with the
analytical results for melts of recovered cans (39)
summarized in Table 10. However, tin is likely to de-
crease in future years as industry replaces tin plate with
tin free steel (or aluminum) (38).
38
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Because beverage cans have such great impact on the com-
posite composition of ferrous scrap, and because use of
these cans vary by season, it is necessary to examine
possible variations in composition of the magnetic metals
portion of municipal solid waste for each quarter of the
year. Beverage containers (aluminum and steel) account
for 39.3 percent to 45.4 percent of metals used in making
cans (42) by season (See Table 10). It can be assumed
that few companies would store cans for long periods of
time because their bulk would make such a policy un-
economical. Thus, most cans are filled soon after manu-
facture. Furthermore, beer and soft drinks are usually
fast moving items, i.e., have a short shelf life at the
consumer sales level. With these considerations and
applying the data in Table 11 to averages for the year,
the aluminum content of recovered steel cans might increase
10-15 percent in summer months over winter months. Accord-
ingly, the overall tin content might be slightly lower
in the summer months as result of the effect of tin free
steel beverage cans.
Recovered cans will contain organic materials from inks,
liners, sealants, coatings and some contamination from
other wastes.
Aerosol cans will contain non-metallic materials used for
gaskets, valves, and buttons. One estimate (38) is that
39
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1.9 percent of the weight of recovered cans is organic
material. Examination of magnetically separated cans
shows 1.1 percent by weight is organic coating and 5
percent of the total weight is other organic material
(38).
The above discussion is based on expected national averages.
However, the composition of the can portion of the recovered
steel might vary considerably in a city where glass and/or
aluminum beverage containers are in widespread use. The
general effect of the aluminum, lead, tin, and organic
material contaminants on reuse of the recovered cans, is
discussed in turn.
Aluminum need not be a problem in steelmaking; it is
frequently added to melts as a deoxidizing agent but at
the end of the steel making process, not in the initial
charge, as would be the case if aluminum is in the scrap.
Should an excessive amount of aluminum be included, and
oxidized to slag alumina, it can be detrimental (32).
Lead is insoluble in molten steel and unlikely to inter-
fere at the concentrations expected; reportedly, it
oxidizes at steel melt temperatures and the lead oxide
is collected as a dust from the stack emissions (43).
Tin and copper in sufficiently high concentrations are
tramp elements and are to be avoided in steelmaking (33).
Organic materials burn-off during the melting of the steel.
40
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Table 10
Reported Compositions — Three
Classifications of Ferrous Containers
TFS AE TSE
Tin Free Aluminum Tin Steel
Component Steel End End
% % %
Organic Coating 1.83 1.83 1.83
Aluminum 10.20 10.20 0.00
Lead 0.01 1.83 1.84
Tin 0.00 0.42 .48
Steel 87.96 85.71 95.85
Total100.00 100.00 100.00
Source: E. J. Ostrowski, Recycling of Tin Free Steel
Cans, Tin Cans and Scrap from Municipal
Incinerator Residue, Presentation at 79th
General Meeting/ American Iron and Steel
Institute, New York, May 26, 1971.
41
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Table II
1971 Seasonal Variations In
Metal Mix
Beer & Soft Drink Metal Containers
(In base boxes of metal consumed; a base box is an area of 31,360 square inches of
Metal)
£ Beer & Soft*
Drink Shipments
All other Cans
Percentage
Beer & Soft Drink
*Includes aluminum and Steel
Year
(OOCFsT
64,886
92,734
157,620
41.2%
First
Quarter
(OOO's)
14,284
22,044
36,328
39.3%
Second
Quarter
(OOO's)
17,610
21,155
38,765
45.4%
Third
Quarter
(OOO's)
19,079
28,185
47,264
40.4%
Fourth
Quarter
(OOO's)
13.913
21,350
35,263
39.5%
Source: Adapted from Containers and Packaging, U. S. Department of Commerce,
July, 1972, pp. 23, 26.
-------
They are undesirable as they add an additional load on
air pollution control equipment and are a potential
source of alloying carbon.
The likely effect of tin and copper inclusion in recovered
steel/ and estimates of their possible accumulation with
repeated recycling have been reported. It has been
estimated that after seven months the tin content of in-
gots would stabilize at about 0.03 percent and copper
at 0.08 percent, assuming use of up to 50 tons of in-
cinerated scrap in a 300 ton EOF heat (39). These es-
timates are based on analyses of steel from municipal
incinerator residue which has a higher copper content
than non-incinerated can scrap. Also, there are other
conditions which could result in more or less tin accu-
mulating in the ingots. The 0.03 percent and 0.08 percent
figures have to be compared with the limits on these
elements permissible for several uses of steel.
In sheet mill products for auto bodies, appliances, etc.,
the limit for critical forming grades is 0.01 percent
tin, with a total residual (Cu, Ni, Cr, Mo, Sn) metals
content of 0.16 percent. Some grades can tolerate more
residuals but these result from failures to make the
critical grades; they are not planned. Consequently,
the inability to control and identify scrap quality makes
it impossible to use non-critical grades of sheet mill
43
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products as outlets for high residual scrap. Deliberately
using high residual scrap, however, has an important
effect upon the accumulated residuals and recycling of
home scrap (that generated in the steel mill). Residuals
in the latter are the averaged result of intake of re-
siduals in virgin raw materials plus those in secondary
materials (44) .
In making base sheet for tin plate or TFS can body stock,
the usual limit is 0.02 percent tin with a total re-
sidual limit of perhaps 0.25 percent. Copper is most
critical, being limited to 0.06 percent in making type L
tin plate. Some grades can tolerate 0.06 percent tin
and 0.06 percent copper with regard to cold formability,
but there are other limitations with regard to hot work-
ability. For grades of sheet steels, which are pickled
prior to coating, copper content is limited to 0.03 per-
cent in order to achieve high pickling rates (44).
"Skelp" for making butt-welded and seamless tubes can
tolerate 0.015 percent tin with the exception of electric
welded tubes where the limit may be as high as 0.06 per-
cent, depending on whether the pipe is to be hot formed. In
most other grades, such as plates, bars, rod, and wire,
tin does not usually appear on the specification. There
is an anomaly here, however, for tin is critical in the
range of 0.05-0.06 percent where the steel surface breaks
up in the primary hot rolling (blooming mill and billet
mill) operations. There is a synergistic effect between
44
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residual copper and sulfur in the reheating fuel so
that at 0.10 percent copper or less, 0.06 percent tin
can be tolerated (45). These limits change when low
sulfur fuel or an oxidizing reheating flame is used,
but steel mills have not had to press the limits in
this regard. Many products could tolerate higher tin
levels, if they could get through the blooming mill with
acceptable yield and surface quality (44).
There are two "background" effects with which mills
contend:
(1) Hot metal (iron) from virgin raw materials
typically contains 0.003 percent to 0.005
percent tin. In special cases, this may be
appreciably higher.
(2) With about 30 percent scrap recycling within
the steel mill itself, the permissible residual
level of the typical product made dictates
the permissible level of residuals in "home"
scrap.
The typical top-blown oxygen steelmaking plant is operate
in balance with 30 percent home scrap and 70 percent
hot metal. Scrap preheating or bottom-blowing (Q-BOP)
permits 40 percent scrap and 60 percent hot metal in
oxygen steelmaking. Open hearth operations have a
great range of flexibility; 30-10-60 as above is typical.
However, open hearths can operate at about 30 percent
home scrap, 40 percent purchased scrap and 30 percent hot
metal. The extreme case, of course, is the electric
45
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furnace using 30 percent home scrap and 70 percent pur-
chased scrap (44).
These percentages are approximations and in practice are
influenced by the silicon content of hot metal and the
home scrap yield which varies by product and by process.
For example, a plant working exclusively with continuous
casting and making only merchant bar products should be
recycling 20 percent scrap or less (44).
Recovered cans contain from 86 to 96 percent steel (Table
10) compared to a 65 percent iron content of pure Fe304,
and to approximately a 25 percent iron content for taconite
ores (before beneficiation). Thus, scrap steel could be
charged as a high assay ore to blast furnaces if some other
conditions were met. These include lack of persistent
tramp elements, potential air pollutants, and a sufficiently
high bulk density such that the furnace could be charged
at reasonable cost with existing materials handling equip-
ment. A bulk density of at least 75 pounds per cubic foot
is needed for this purpose (46) . In addition, the steel
must be free flowing because of the nature of the operation
of a blast furnace. The use of scrap steel in the blast
furnace has been discussed by Ostrowski (32) . Bulk density
is also important for steelmaking, whether in open hearth,
EOF, Q-BOP, or electric furnaces. Some of the reasons
for this are ability to charge a sufficient weight in a
46
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given time and maintaining a low surface to volume ratio,
hence a low degree of oxidation with, subsequent melt loss
(47). If the scrap steel is to be used in an electric
furnace feeding a continuous strand casting machine, the
aluminum content in the steel becomes critical. Aluminum
is not easily oxidized in the melt in an electric fur-
nace as it would be in other furnaces, but does readily
oxidize at the continuous casting nozzle. The resulting
oxide, or dross, can clog the nozzle (48). Although
methods have been developed to avoid this, they are ex-
pensive to install and operate (49).
Tin plate steel cannot be detinned by heating. At re-
latively low temperatures, tin alloys with iron (33).
Detinning is accomplished by dissolving the tin (and any
accompanying aluminum) in hot caustic solutions (50).
The recovered cans must not be balled, or otherwise
flattened to a form such that the caustic cannot reach
the tin, or cannot easily drain after the detinning process
(51).
Little information seems to be available that could be the
basis for choosing a specification for the ferroalloys
industry. On contacting representatives of this industry,
we learned that some processes are geared to a particular
source of scrap and that the processors would not be
interested in discussion of needs and uses for other
sources. (These discussions were before the acute scrap
shortage of 1974).
47
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The use and needs of precipitation iron in the re-
covery of copper from low-grade ores has been discussed
(52). Almost any form of scrap capable of being readily
and uniformly attacked by sulfuric acid is usable.
Scrap steel cans can be utilized for cast iron and cast
steel. The properties of the melt meet commercial
standards, based on laboratory results (53)(54). Ten-
tatively, the target specification can be the same as
for blast furnace use, pending publication of research
results using such scrap in foundries (45).
No specification was considered for steel recovered from
incinerator residues for several reasons. If improperly
incinerated, the cans might be too oxidized, even for use
as a precipitation iron (55) . Also, such cans pick up
trace amounts of copper (56) making the steel "short" and
unsuitable for rolling (30). The steel industry has
difficulty utilizing steel recovered from incinerator
residues (57). Cans recovered from municipal waste can-
not meet the specifications for form and density of
standard scrap designations, such as No. 1 and No. 2 bundles
described in Appendix A. Properly prepared and baled,
can bundles come closest to No. 2 bundles (different from
No. 2 Heavy Melting), but by description are not No. 2
bundles.
The content of aluminum, tin and lead in all magnetic can
bundles need not be detrimental to steel making processes
(43) if sufficient hot metal is available to dilute the
48
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tramp elements. The amount needed will depend on the
targetted alloy end use for the mix. It may be possible
that reshredding of bi-metallic cans, followed by mag-
netic separation, can be used to reduce, but not eliminate,
the aluminum content (32).
Scrap steel from municipal solid waste is potentially use-
ful in various steelmaking processes and other tradi-
tional uses of scrap. The available information concerning
the effect of alloying and tramp elements on these uses
does not permit a "cookbook" approach to specifications.
The art of steelmaking is too complicated for gross
simplifications regarding scrap utilization. The infor-
mation above is included for background guidance. Many
target specifications will have to be negotiated between
buyer and seller depending on the end use intended for
the scrap. The use of resource recovered steel scrap
in steelmaking, and the iron and steel foundry industry,
has recently been reviewed, including a discussion of the
effects of contaminants (45).
49
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ALUMINUM
Background
Aluminum alloy properties and metallurgy are extremely
sensitive to the concentration of alloying and tramp
elements (58) (59) . There are more than 150 different
recognized (registered) wrought alloys and more than 75
different casting alloys of aluminum designated by the
Aluminum Association (60) . Producers mix standard pro-
portions of alloying metals with pure aluminum (primary
metal) to create the alloys. They also add scrap of
known composition, when appropriate, and adjust input
of alloying metals accordingly. "Home scrap" is pre-
ferred, but primary producers also use purchased scrap.
Reportedly, about 20 percent of aluminum sold is from
secondary sources (61) .
Secondary smelters account for almost 80 percent of
scrap aluminum purchases from dealers (61). They may
use new scrap (turnings, clippings, etc.) or old scrap
(such as castings, sheet, and pistons). The smelters
blend scrap from many sources, diluting aluminum which
contains unwanted alloying metals.
Currently, scrap buyers recognize at least eighteen
grades of aluminum (1) (3). Classification is made
chiefly by source and physical description rather than
by elemental analysis. In sharp contrast, alloys of all
50
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sorts and of primary and secondary casting alloys are de-
signated by chemical composition.
If aluminum recovered from municipal waste is to be re-
used by the primary aluminum producers, it must be pro-
cessed to fall within one of the three broad categories
of wrought, extruded, or cast products. The reason for
this is that this categorization determines price. All three
types could be utilized by secondary aluminum smelters;
the highest potential value for aluminum separated from
municipal waste appears to be for re-use in new melts of
wrought alloys. Obviously, the material sold should not
be contaminated with other alloy types which may inter-
fere with this use.
Aluminum in mixed municipal refuse may consist mostly of
beer and beverage cans (70 percent in one city) depending
if that is the predominant form of packaging in the
marketing area (62) . The remainder is miscellaneous
foil, extrusions, and castings. The likely composition
of alloys used in consumer products are listed in Table
12. Sensibly, then, the aluminum might be recovered in
two fractions: one consisting of mostly beverage cans
and foil and the other consisting of miscellaneous ex-
trusions, castings, etc. The reason for including foil
with cans is that foil is either 1100 series alloy
(commercially pure) aluminum or 3000 series alloy, such as
3003. Both materials would be diluents for the 3004 alloy
51
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Table 12
Examples of Aluminum
Items Pound
In Municipal Waste
Likely
Alloy
Used
Products
Nominal Chemical
Composition
(Balance Al)
1100 Series
3003
3004
5005
5050
5182
5255
5257
6063
6463
Cooking utensils
Hair curlers
Lightweight kitchen foils
Product wrappings
Cooking utensils
Toys
Pie Plates
Heavy foils
Lamp bulb bases
Beverage container bodies
Annodized decorations
Appliances
Appliances
General Purpose Tubing
Beverage container tops
Automotive trim
Lawn furniture
Automotive trim
Window frames
Automotive trim
99.0% Al
"Commercially pure"
1.2% Mn
0.6% Si
0.7% Fe
1.2% Mn
1.0% Mg
0.3% Si
0.7% Fe
0.8% Mg
0.4% Si
0.7% Fe
1.4% Mg
0.4% Si
0.7% Fe
0.35% Fe
0.35% Mn
4.5% Mg
0.2% Si
2.4% Mn
0.4% Mg
0.7% Mg
0.11% Si
0.35% Fe
0.7% Mg
0.2-0.6% Si
52
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Table 12 (continued)
Examples of Aluminum
Items Found
In Municipal Waste
Likely Nominal Chemical
Alloy Composition
Used Products (Balance Al)
(Castings)
13 Typewriter frames 12.0% Si
2.0% Fe
43 Architectural Ornamentation 5.0% Si
2.0% Fe
Source: Adapted from P. Farin, G. Reibsamen, Aluminum,
Profile of_ Industry, McGraw-Hill, New York, 1969
53
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used for aluminum can bodies and 5182 alloy used for can
ends (63). Alloys 3004 and 5182 melted together yield
a compostion sufficiently similar to 3004 that a mixed
metal of the two can be used to produce new 3004. Some
magnesium is lost on re-melting recovered cans (64).
Recovered aluminum must be free of sand, grit, and parti-
cularly glass. At the melt temperature, aluminum will
reduce the silica in glass to silicon, which will alloy,
and cause the melt to be off-spec. Higher silicon-con-
taining alloys are not desirable for wrought products
but find use as extrusion or casting alloys (63) (64).
Iron content is similarly a problem and such contamination
must be kept low. Likely, this could be accomplished
through proper processing when recovering the aluminum.
Carbon does not alloy with aluminum (58). Organic materials
in recovered aluminum will burn-off in the furnace and
either cause an additional load on the air .pollution
control equipment or be included in the dross (slag).
In either case, organic materials are contaminants in
that they add to processing costs.
The aluminum must have a low surface to volume ratio
(i.e., a high bulk density), hence baled or briquetted
to avoid melt-loss during re-smelting (63) (64). For
similar reasons, the specification must include a limit
on fines.
54
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Specifications
Aluminum specifications were pursued with two primary
aluminum producers. Their acceptable limits of alloying
and tramp elements are different. As a result, two
specifications for the aluminum fraction consisting
mostly of cans and foil are proposed. Presumably, the
specification calling for lower contents of alloying
elements (especially Si and Pe) is for metal which will
be reused in wrought products. No specification is needed
for the other fraction of aluminum - the miscellaneous
extrusions and castings. Its composition is expected to
vary over wide limits. Aluminum is a high value commodity
and even this down-graded variable composition scrap
should be saleable at a reasonable price.
Tables 13 and 14 are the target specifications for the
can and foil fractions. The following notes apply to both
tables. The scrap can be shipped either loose (in
covered trucks or railroad cars) or loosely baled or
briquetted to a maximum density of 30 Ibs./cu. ft. Alumi-
num may be passed through a hammermill, rod mill, grinder,
or other kind of shredder, but piece size must be such
that 100 percent is retained on a 12 mesh screen. The
metal should be screened to reduce fines such as dust,
dirt, sand, etc. The aluminum must be free of heavy media,
dried prior to shipment, and not obviously corroded.
Analyses will be made on the melt of a total shipment or
55
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Table 13
Chemical Composition Limits of Al Scrap
Target Specification for Reuse in Wrought Alloys
Element
Si
Fe
Cu
Mn
Mg
Cr
Zn
Pb
Sn
others
dirt, fines
loose organics
Al
Maximum Contents'
Grade I
0.3
0.7
0.40
1.50
2.00
0.10
0.25
0.04
0.04
0.12
1.0
2.0
Notes
b
c
d
e
remainder
Notes:
(a) Downgrading of the selling price can be in pro-
portion to the extent of the dilution with primary
metal necessary to achieve the composition limits.
Maximum permissible dilution will be 50 percent.
(b) As alloyed.
(c) Less than 0.04 each
(d) Maximum quantity minus Tyler screen size No. 12.
(e) Not including can coatings.
(f) For samples of melt loss exceeding 10 percent, the
selling price may be further downgraded in proportion
to the melt loss.
56
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Table 14
Chemical Composition Limits of Al Scrap
Target Specification for Possible Reuse in Cast
and Secondary Alloy Products
Maximum Contents
Element^ Wt.%
Si 1-0
Fe 1-0
Cu 2.0
Mn 1.50
Mg 2.00
Cr 0.30
Zn 2.00
Pb 0.30
Sn 0.50
Others 0.12*
Fines 3.0
remainder
*Less than 0.04 each
Note: Permitted maximum contents of alloying and tramp
elements of a grade for use in secondary products are
listed above. Any scrap shipped, which upon analysis fails
to meet specifications, shall be rejected and at seller's
option be returned to seller at his expense or sold to
buyer at a reduced price, to be negotiated.
Metal not meeting the composition limits stated will be
down-graded to a category where the selling price will be
negotiated on an individual shipment basis.
57
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Table 14 (continued)
Note:
The scrap aluminum in mixed municipal refuse must be
separated from all other materials. If the material is
reclaimed using dry processing following thermal treat-
ment of the refuse, it must be baled to a minimum
density of 30 pounds per cubic foot. If the aluminum is
separated from raw refuse or if wet processing techniques
are used to separate the aluminum, the aluminum must
be shredded or dried prior to baling. The shredded
material must pass over a U.S. Standard 12 mesh screen to
reduce fines (dust, dirt, sand, paint, etc.). Pines
must not exceed 3% of gross weight. The finished product
must be baled or briquetted to a minimum density of 30
lbs./ft.3 Analyses will be on the melt of a total ship-
ment.
58
-------
on a statistically determined sample of that shipment
(there is not yet any accepted way of such sampling) by a
method such as ASTM E-34-68 or equivalent.
The chemical analysis of the melt from the scrap batch
will determine the grade of that scrap. The magnesium
composition limit is calculated on a 75:25 by weight
mixture of alloys 3004 and 5182, respectively.
Analyses
In order to verify the proposed specifications, aluminum
samples which were hand picked from the municipal refuse
in Tampa, Florida, and New Castle County, Delaware,
were chemically analyzed (65). It was previously deter-
mined (62) that aluminum comprises about 1.0 and 0.6
percent respectively of the municipal waste in these
two locations. The difference is accounted for in that
Tampa's waste stream contains a greater proportion of
aluminum beverage cans.
The Tampa sample was divided into two portions: (a) cans
and (b) mostly formed containers, including miscellaneous
items such as ice cube trays and a water pitcher. The
results of chemical analyses of these portions are shown
in Table 15. The high iron content in formed containers
need not be considered typical because magnetic separation
would be expected to remove steel to lower levels than
hand separation. This is confirmed by the Tampa sample
59
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which was mostly cans. It was magnetically separated
and analyzed; the iron content was 0.5 percent.
The sample hand picked from New Castle County, Delaware,
was mostly formed containers and foil, with some pieces
of screen. The average chemical composition is shown
in Table 15. Again, the high iron content is probably
due to steel cans which were not removed in the hand-
picking. The analytical results support the use of
calculated average alloy compositions in determining the
chemical specifications of recovered aluminum.
Also shown in Table 15 are the analyses of aluminum re-
covered from air classification and heavy media sepa-
rations (66). In spite of using ferrosilicon as the
media, a mineral which could cause contamination of the
aluminum with both iron and silicon, and in spite of the
solubility of this mineral in molten aluminum (67) , the
aluminum recovered this way lends confidence that the
specifications of Tables 13 and 14 can be melt with care-
ful processing. Other means of recovering non-ferrous
metals have been described (68).
60
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Table 15
Chemical Analyses
Aluminum From Municipal Refuse
Tampa
Element Formed Containers
Si 0.2
Fe 3.0
Cu 0.2
Mn 0.3
Mg 0.1
Cr 0.03
Ni 0.02
Zn 0.05
Ti 0.01
V 0.00
Pb 0.02
Sn 0.01
Tampa After
Mag. Separated
0
0,
0,
1,
2
5
1
0
1.2
0.01
0.00
0.08
0.02
0.00
0.00
0.00
New Castle Co.,
DW (Mixed
Packaging)
Metal Separated
by Heavy Media,
ref. 66
0.2
1.2
0.1
0.5
0.02
0.00
0.00
0.08
0.02
0.00
*
0.00
0.18
0.51
0.10
0.82
0.45
0.01
0.00
0.04
0.03
-
0.01
0.05
*Pb was 0.00 in one sample and 0.6 in second sample
Analyses performed by L. C. Blayden, Alcoa Technical Center, Merwin,
Pennsylvania.
-------
OTHER NONFERROUS METALS
Background
Based on analyses of incinerator residues (69) , the ex-
pected composition of the nonferrous metal fraction
(excluding aluminum) of municipal wastes is:
Metal Expected Wt.% Range Wt.%
Cu 55 47-70
Zn 35 33-40
Sn 1
Pb 2 0.5-0.3
When sampling waste it is apparent that the nonferrous
fraction consists of every conceivable material and form
(62), including keys, coins, light bulb sockets, pieces
of plumbing fixtures, and all sorts of hardware (70).
The secondary materials industry has developed a large
number of specifications to cover such materials from
industrial wastes (1) (3), but for the most part, these
specify materials according to their origin. Examples
are the several specifications for copper, including
copper wire, heavy copper (clippings, pipe, tube, etc.),
light copper (bottoms of kettles, boilers, roofing,
etc.) and automobile radiator cores. The existing NARI
specifications (1) may be applicable to the nonferrous
metals in mixed municipal waste after separation and
sorting. They are not applicable prior to sorting.
The mixture of nonferrous metals in the refuse after
sorting is somewhat analogous to the mixture of non-
ferrous metals resulting from auto shredding. Conversa-
tions with auto shredder operators (71) indicated that
62
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the nonferrous concentrate from shredders consists of
mixed nonferrous metals, including non-magnetic stain-
less steel, heavy rubber, dirt, glass, and some magnetic
material missed during the prior processing. The price
paid by the processing or separating plant for this con-
centrate is on the basis of the nonferrous metal con-
tent recovered. No value is assigned to magnetic
materials nor is an extra charge made for disposing of
the non-metallic materials. Stipulations are usually
made that the seller will not hand-pick copper or
other red metals. The processor makes deductions from
the contained nonferrous metal content of about 4 per-
cent for moisture and 10 percent for smelting loss of
zinc. There is an additional deduction in the price
paid if the feed is particularly low in metal values or
otherwise so "dirty" that it requires extra processing.
The mixture of nonferrous metals from mixed municipal
refuse is expected to contain little dirt (7). (The
likely contaminants will be stones and gravel.)
processing of the mixed, nonferrous metals from auto
shredder scrap results in some losses, approximately
20 percent — less than would be obtained from hand-
picking. This can be accounted for as a 15 percent melt
and oxide loss from zinc sweating and a 6 percent loss
due to less than 1/4 inch fines. The mixed, nonferrous
metals recovered from municipal waste should be an
ideal feedstock for a processor of auto shredder scrap.
63
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Because of the operating nature of this industry, a
satisfactory specification for mixed non-ferrous metals
may only need be qualitative.
Recommended Specification
A proposed specification for mixed, nonferrous metals in
municipal waste is given in Table 16.
Analysis
Samples hand picked by NCRR personnel from municipal waste
contained diverse mixture of nonferrous metals. It is
impossible to quantify what may be in them or to predict
composition in advance. One sample of this mixture, re-
covered by heavy media processing (66) , contained 9 percent
by weighC stones. It was otherwise free of non-metallic
materials. Figure 2 is a photograph of this mixture.
GLASS
Background
Recovered glass can be re-used in containers, in secondary
products, such as building materials, or as an aggregate
substitute such as in Glasphalt (72). The requirements
for each use differ widely.
Raw materials for glass container manufacture are care-
fully controlled so as to maintain batch-to-batch re-
producibility (73). The feedstock or "batch" to the
64
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Table 16
Target Specification for Other
Nonferrous Metals
Contents: Miscellaneous nonferrous metals,
including non-magnetic stain-
less steel
Size: 100% retained in 3/16 inch
screen (note a)
Cleanliness: Minimum 80% by weight metal
(note b)
Form: Loose, not balled and dry
Notes:
(a) The mixture may be screened to separate pieces too
small for handpicking of red (copper bearing) metals,
approximately 1 1/2 inches in size. Smaller sized pieces
processed and recovered by other than handpicking.
(b) Price may be down-graded on basis of content of nori-
metallics. Subject to negotiation.
65
-------
en
9
•M
\
Figure 2. Sample of mixed non-ferrous metals recovered from municipal solid
waste by processing through heavy media (66) . This sample contained
92 percent metal; the remainder was mostly stones.
-------
glass furnace (or tank) must be free of refractory
particles which will not melt; they are the cause of
"stones" in the glass (a ceramic inclusion and a
possible point of stress concentration which has an
undesirable appearance and may cause weakness and bottle
breakage) (74) (75). A bubble in glass, known as a
"seed," also causes unaesthetic appearance and can lead
to weakness. Recovered glass can cause both stones and
seeds if not processed properly. For example, bottles
made from a batch containing 4.8 percent glass cullet
supplied by Bureau of Mines Incinerator Residue re-
source recovery plant, apparently had more metallic
contaminants, which are likely to cause seeds, than
were in standard glass making materials. These bottles
had up to 48 seeds per ounce compared to 5 or 6 seeds
per ounce for the controls. This test of the recovered
glass was on full scale production machines (76).
No mention was made of stones in the test glass.
A potential source of stones is aluminum. At glass
melt temperatures in the absence of air, aluminum re-
duces silica to silicon, which is refractory and forms
the stones (75).
Additionally, glass must be free of ferrous materials
which will change the glass color. Amber and green
glass contain varying small amounts of iron in the
Fe II and Fe III oxidation states, and chromium in
67
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several oxidation states, which will affect the color
of the final glass when added as cullet. Chromium is
especially troublesome, because its oxidation states
range from +3 to +6, each of which impart a different
shade of green.
Reportedly, it has been industry practice to use cullet
in the glass formula of from 15 to 20 percent by
weight (73). However, subsequent work, perhaps in
anticipation of greater availability of cullet, has
shown that as much as 100 percent can be used in pro-
duction melts, under appropriate circumstances (77).
Several colors of glass can be recovered from mixed
municipal waste. About two-thirds of the glass produced
for containers is flint or clear (74). Georgia Green
TJ
(light green) is used for the familiar Coke bottle;
Emerald Green is the deeper color of other soft drink
bottles; Champagne Green is the deeper color of wine
bottles: amber glass is largely used for beer bottles.
Also, when refuse is sampled, there are always small
amounts of blue and opal glass. The mix between amber
and green seems to depend on the part of the country,
with more green on the west coast than the east. It is
likely that a materials separation plant operating on
mixed municipal refuse will be able to separate flint
(containing some Georgia green) from mixed colors and
leave behind a mixture of amber and green (78) . It
68
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may also be possible to separate the green from amber,
but there will always be a fraction of color-mixed
(7), which can be used in the manufacture of new con-
tainers (77) .
To date, there is insufficient experience using glass for
building products to be able to write specifications.
Some of the uses seemingly do not require a clean pro-
duct (72). Use in brickmaking may require specifications
for particle size and organic content (79).
In order to provide guidance for development of MSW sep-
aration systems, the Glass Container Manufacturers In-
stitute developed preliminary guideline information which
would describe a typical cullet quality acceptable for
use in glass container manufacturing furnaces (80) and
reflects manufacturing experience. The bases for this
specification have been described (75).
These quality guidelines for cullet were designed so that
the material could be used as full substitution for in-
plant cullet. In other words, large percentages of this
cullet could be placed in the batch without potential
damage to the furnace and without lessening the quality
of the finished product. (Along with guideline infor-
mation, GCMI also recommended quality control methodology
to assure proper preparation and examination of the
cullet samples.)
69
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The purchase of cullet in the past commonly called for
glass which was "clear, color-sorted, and free of metals."
It was relatively easy to follow these instructions be-
cause much of the cullet was obtained regularly from
brewers and bottlers by cullet dealers, some of whom
processed or beneficiated the cullet meet customer re-
quirements. Increasing labor costs over-priced these
sources so that less and less cullet was purchased.
The cullet generally was crushed for handling and washing,
and left in the +3/4 inch size range for easy identi-
fication of color and such foreign material as stones and
metals, as well as to facilitate melting in the batch.
Generally, sizes over 2 inches cause handling problems
for container manufacturers. Finely ground materials
also present problems of storing and handling the
materials. In addition, color identification would be
difficult, if not impossible, for sizes less than about
3/16 inch in size. Small size cullet presents another
problem because this condition prevents good drainage.
A cullet pile or sample should show no drainage, but
small sized cullet would retain a higher percentage of
water if only by capillarity.
Other properties of purchased cullet can be designated
based on manufacturing experience in the industry. The
maximum amounts allowed are listed as the percentage
fraction, dry weight basis, in Table 17.
70
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Table 17
Guidelines for Gullet as a
Direct Replacement
for In-Plant Gullet
Metals; maximum size 1/4 inch: magnetic, 0.05 percent
~~~ non-magnetic, 0.015 per-
cent.
Organics; maximum amounts: paper and plastics, 0.05 per-
cent other, 0.05 percent
Solid Inorganic Material other than Metals:
Maximum size 1/4 inch. Refractory, 0.05 percent,
Note: When the sample is believed to contain
refractory inorganic material, the cullet sample
will be subjected to the following added speci-
fications: A one-pound sample may not contain
more than 2 particles in the -40+60 mesh size
range.
Mixed Color Glass
Color of Color of Batch
Cullet Amber Flint Green
Percentage cullet in batch
Amber
Flint
Green
90-100
0-10
0-10
0-5
95-100
0-1
0-35*
0-15
50-100
*Does not apply to Ultra-violet absorbing Emerald Green glass
Source: Derived from information supplied by J. Abrahams,
Glass Container Manufacturers Institute, Washing-
ton, D.C., 1973.
71
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The guidelines of Table 17 were the basis for negotiating
the target specification of Table 18 (81). The principal
difference is in the content of organic material. The
specification for color sorting is based/ in part, on
the expectation of electronic color sorters C78)(82).
There have been recent tests of the ability of available
equipment to recover glass to the specifications of
Tables 17 and 18 (78) . Preliminary results are that
these specifications were not achieved with the equip-
ment described. At the same time, glass melting research
indicated a need for decreases in the permissible level
of refractory impurities. The subject is still open and
basis for discussions ongoing within ASTM Committee E-38.
Analyses
The requirement in the target specification for counting
the number of refractory particles translates into a
maximum refractory content of about 0.0003 percent by
weight refractories. When glass was separated from
shredded municipal refuse (27) , it was noted to contain
many small pieces of egg shell. These are calcium
carbonate, which will flux, and is a permissible foreign
material in cullet (76).
There have been some tests of individual processing steps
as a means of preparing glass to the target specification
of Table 18. Heavy media separation is capable of
72
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Table 18
Target Specification for Gullet for Use
in Container Manufacture
Liquid
Organic
Sizing
Magnetic Material
Non-magnetic Material
Ceramic
Refractories
Mixed Glasses
Gullet to show no drainage from
sample. The cullet must be non-
caking and free flowing.
Maximum 1.0%
0 on 2" bar screen and be retained
on a 100 mesh screen.
Less than 0.5% maximum size 1/4".
Less than 0.02% above 60 mesh.
.05% maximum size 1/4".
One pound sample may not contain
more than 2 particles greater than
40 mesh in size, nor 20 particles
in size range between 40 and 60
mesh.
Future glass container melting
research may indicate a greater
tolerance for refractory particles,
in which case, the specification
may be altered.
Cullet that does not meet the color
specifications below, Will not
be considered color sorted.
% in Cullet
% Amber
% Flint
% Green
Cullet
Amber
90-100
0-10
0-10
Flint
0-5
95-100
0-1*
Green
0-35
0-15
50-100
*Flint cullet can contain either 1% emerald green, or
10% Georgia green, or combinations of both with 1%
Georgia green equivalent to 1/10% Emerald Green.
73
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separating glass from extraneous matter and some stones
(83). In other work (27) , glass was separated from
shredded municipal refuse originating in New Castle
County, Wilmington, Delaware by screening the refuse
portion that sank in water. Wet screening and separation
on a Wilfley table (27)(84) were the only techniques
used to prepare what appeared to be clean glass. Organic
contamination was tested by loss on ignition at 475°C.,.
and found to be from 0.6 to 1.2 weight percent. (At
temperatures higher than this there are weight losses
due to loss of water of hydration, CO2, etc.) This
sample was then analyzed for content of refractory part-
icles. The results are summarized below showing a great
excess of refractories above permitted levels by the
specification.
Refractory Particles Per Pound of Original Sample
Material 4-40 Mesh +60 Mesh
Sillimanite 96 120
Corundum (Single Crystal) 12 48
Corundum (Tabular) 60
Unidentified White Ceramic 72 —
Totals 240 168
These results emphasize how readily refractory material
can be included in the glass fraction.
74
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INORGANIC FINES
Background
Because almost all proposed MSW processing concepts start
with a size reduction (shredding) step, it is reasonable
to assume and it has been found (27) , that friable
materials, particularly glass, will be reduced to small
pieces. Contacts with representatives of user industries
indicate that most do not want fines. For example, in
the glass industry cullet sized larger than 100 mesh is
usually required for reuse in the furnaces (74) (75).
Additionally, if color separation is performed to upgrade
the glass, sorting equipment limitations (78) (82) currently
prevent classifying particles less than 3/16 inch in
size. A study of the outputs of MSW shredders in eight
selected cities indicate that as much as 85 percent of
the glass content is reduced to minus 3/16 inch size (27).
Water sink-float separation (27) of shredded MSW samples
showed that inorganic fines (principally glass) will be
the major component among solids passing screens following
water elutriation. The material passing through will have
to be landfilled if it does not find market acceptance.
Best possibilities for utilization appear to be as sand
and gravel substitutes.
One market opportunity may be as an aggregate ingredient
in asphaltic paving mixes. Much work has been done in
trying various mineral tailings and dusts in asphalt
road surface mixes at least as long ago as 1921 (85).
75
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More recently, waste glass has been used with some success
in road construction 086).
While use in standard pavement offers large volume out-
lets for finely divided inorganic stones and other
materials, their sales worth cannot be high because they
compete in this application with inexpensive materials.
Other opportunities may exist with small potential volume,
but with the advantage of higher selling prices. Perhaps
the more promising possibilities are as "pea gravel"
in porous concrete (87) and as a clay substitute in
brick making (79).
Target Specification
Considering the relative uncertainty about ultimate use,
only a general specification for inorganic fines can be
written. It is presented in Table 19.
While processing may conceivably upgrade the inorganic fines,
it is unlikely that the added costs can be justified by
significantly higher market values. With this in mind,
the target specification of Table 19 was written for
essentially a by-product which could be used in appli-
cations where impurities could be tolerated, for example,
paving, brick-making, etc.
Little difficulty is expected in using the inorganic
fines in brick manufacture. U.S. Bureau of Mines has
successfully produced quality bricks substituting
pulverized incinerator residue (glass-rich and metal-free)
76
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Table 19
Target Specification
For Inorganic Fines
As a sand and fine gravel substitute, particle size
distribution will be such that 98 percent by weight will
pass through a 3/16-inch screen. Minimum size 200 mesh
to avoid dusting.
Content will consist of less than 1 percent organics
after wet screening, and less than 1/2 percent metallics
by weight. The mixture will conform to the following
description:
Non-combustible and free flowing
. Less than 1% water solubles
Moisture less than 10%
77
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for clay (79) . The finished experimental bricks met
ASTM standards (ASTM C62-66 and C67-66) and required
less fuel for the kiln than regular brick.
Possibilities for use of the fines in paving mixes are
good according to members (88) of ASTM Committee D-4,
Road and Paving Materials. However, market values will
be low. There are many sources of minus 3/16-inch in-
organic materials, for example, sand, mine tailings,
process wastes (89) . The only problems associated with
using such abundant supplies of material in roadway
construction have been water absorption and roundness
of shape. Water retention in asphalt leads to swelling
and cracking, often within a year of application. This
would indicate that organic material contained in the
fines would be undesirable because of potential to
promote formation of small voids and retain water (90).
This could be avoided; tabling of the fines likely
would remove the organic materials if water elutriation
and wet screening do not reduce them to an acceptable
level.
The elutriating step can also be used to adjust the pH
of inorganic fines over a range of approximately 6 to 9
by adding acids or bases to the water so as to achieve
compatibility of the glass fines with paving mixes. The
exact pH value, however, is not particularly important
for most applications. For example, fines to be used in
hot asphalt could vary from acidic to basic over a wide
range without significantly affecting physical pro-
perties. The mechanical characteristics, i.e., angularity
of piece shapes, are much more important for this use
than chemical bonding (90).
78
-------
Moisture in the fines should not present problems as
long as the moisture content is relatively predictable.
The material could be dried in a hot asphalt plant during
manufacturing (86).
The only advantage of glass fines over commonly used rock
aggregate would be that the angular shape of the glass
fines should impart more strength (88) to pavement than
would spherical sand, for example. A disadvantage may
be that hydrated lime would be needed with the inorganic
fines, perhaps in the range of 1 to 2 percent, to promote
adhesion. This added expense is necessary because, without
the lime/ glass surface wetting will be insufficient to
the detriment of paving physical properties (ASTM D242-70,
D693-71a, D694-72, D1073, D1074-60, etc.)
A need exists throughout much of the United States for
plus 3/16-inch size aggregate. Although inorganic fines
likely could be sintered to produce plus 3/16-inch material
ASTM officials of Committee D-4 (88) were negative about
prospects. Upgrading costs could not be covered by
increased selling prices of the larger pieces sizes.
The recommended specification for inorganic fines was
written loosely around the expected nature of the glass-
rich by-product — without requirement for further
processing. Naturally, the specification can be tightened
to fit individual user needs as markets develop and se-
condary processing becomes economically viable.
79
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Refuse Derived Fuel
(Mixed Organics)
Background
Several of the dry separation systems which have been
proposed for resource recovery (5) from municipal waste,
and the generalized method for dry separation shown in
Figure 1, utilizes an air classifier to separate the
metals and glass (including stones and other heavy
materials) from the light mixture of predominantly paper
and film plastics. This latter category is mostly organic
(carbon containing) and, therefore, suitable for use as
a fuel. Similarly, wet processing systems can be used
to prepare a dewatered, primarily organic fraction for
use as a fuel; for example, the Black Clawson system (91)
and a similar scheme proposed for Norwalk, Connecticut
(92).
In April, 1972, the City of St. Louis, began shipping
shredded, mixed municipal refuse (with the magnetic metals
removed) to Union Electric Company to be used as a fuel
in electric utility boilers (93) along with coal, as a
demonstration program. After approximately six months
of operation the experiment was proceeding well enough
to encourage further burning of shredded refuse as a
supplementary fuel but with the qualification that an
air classification step be added so as to remove the non-
combustibles (94) and this step was added a few months
80
-------
thereafter. The non-combustibles in the fuel interfere
with the materials handling, add to the residual ash,
and decrease the fuel value per unit weight of fuel.
These conclusions are illustrated by the fuel analyses
of the material burned by the utility shown in Table 20
(95) (96). These values may be compared with similar
analyses for common coal for power generation, shown in
Table 21 (97) . Coals are sold according to specifi-
cation; the price paid for the coal is based on
its quality, judged from analyses such as in Table 21 (98).
The composition of the light, organic portions of the
refuse fuel, has been estimated for Norwalk, Connecticut,
and is shown in Table 22 (92) . The materials listed
are either cellulosic or hydrocarbon in origin (except
the leather) and, therefore, are expected to have a high
heat value as a fuel. The potential heat value of such
a mixture can be estimated from published figures of the
heats of combustion of the various components; it is
approximately 8000 BTU Ib., on a dry weight basis. The
ash content will depend principally on the particular
mix of types of paper and the amount of garden waste.
The acceptability of air classified, shredded mixed
municipal refuse as a fuel in utility boilers will de-
pend on its composition, judged from analyses such as in
Table 20 and as compared to analyses such as in Table 21.
In other words, the processing of this fraction of refuse
must be controlled to produce a fuel as close to commonly
81
-------
Table 20
Average Fuel Composition - St. Louis
Dry Weight Basis
00
to
Higher heating value, BTU/lb
Sulfur, Wt.%
Chlorides, Wt.%
Ash, Wt.%
Moisture, as received, Wt.%
Without Air
Classification
29.1
Following Air
Classification
6293
0.20
0.44
29.0
7085
0.16
0.59
24.9
30.1
Source: References 94, 96
-------
Table 21
Properties of Coal As A Fuel (97)
00
00
Heat Value (BTU/lb.)
Sulfur (%)
Ash (%)
Mid-Continental
U.S. Bituminous
11,500 - 13,000
3-5
10 - 12
Wyoming
Sub-Bituminous Lignite
8500 - 11,500
9-12
6500 - 8500
8-12
Note: All values given are on a dry weight basis.
-------
Table 22
Norwalk Domestic Sampling
Composition Analysis
Socio - Economic Income Level
High Medium Low
Components Mean Mean Mean
Fuel Source
oo Paper Products 44.78% 41.25% 36.98%
*" Food & Garden Waste 16.69% 17.00% 20.93%
Plastics 4.01% 4.83% 3.96%
Rubber & Leather .33% .42% .46%
Textiles 2.78% 5.82% 4.21%
Wood .46% 1.03% 1.59%
Sub Total 69.05% 70.35% 68.13%
Source: Norwalk, Connecticut Recycling Plant, Grant Application to U. S
EPA, Volumes I-V, July 31, 1972.
-------
used coals, as possible, if to be used with a minimum
alteration to existing facilities and operating pro-
cedures. No doubt, the refuse-derived fuel will have
an advantage over most coals in that it will be low in
sulfur.
Recommended Specifications
A target specification for fuel derived from air classified,
shredded mixed municipal refuse, termed here Refuse-De-
rived Fuel, or RDF, is shown in Table 23. Two physical
forms are suggested. One is loose and free flowing
to be blown into semi-or full suspension fired boilers,
such as in St. Louis. The other form is briquetted, such
as might be utilized in stoker fed boilers, which has
been proposed for at least one city (99) . It is presumed
that the Refuse-Derived Fuel will almost always be fired
along with another fuel, coal or oil, in the major pro-
portion.
The stated moisture content of 30 percent in Table 21 is
based on an estimate of the maximum moisture content of
refuse likely to be encountered at a processing facility.
Shredding and air classification are expected to reduce
the moisture content compared to the moisture content of
the "as received" refuse, although, this has not yet been
quantified. The other values are chosen based on the
analyses below.
85
-------
Table 23
Target Specification for Refuse-Derived Fuel
Physical Form
Fuel Value
Analyses, dry weight basis
Sulfur
Total Chlorides
Water Soluble Chlorides
Ash
For semi-suspension or full
suspension burning, maximum
particle size 4 inch.
For full-suspension burning,
maximum particle size 1-1/4
inch. For stoker fuel,
briquetted, 1-1/2 to 2 inch
maximum size.
The higher heating value of
each shipment shall be not
less than 5000 BTU/lb., as
received.
0.3% max.
0.6% max.
0.3% max.
15% max.
Moisture
30% max.
86
-------
Analyses
The maximum particle size of the fuel for different
applications is stated on the basis of the St. Louis
experience (93)(94), from the experience of a group
planning to burn shredded industrial waste in a steam
generating boiler (100), and published reports (99).
The other values are chosen on the basis of analyses
of the air classified light fraction of shredded, municipal
refuse. There is reason to believe that minus four
inch material may be acceptable if the air classifi-
cation step produces a fuel consisting of just thin
pieces of paper, film plastics, and the like.
Some few samples of air classified, shredded mixed
municipal refuse (29) have been analyzed. The samples
were prepared using the NCRR Mobile Air Classifier (a
10 ton per hour, zig zag unit) with feedstock from
operating shredders. The fuel analyses were performed
by Ralston Purina Company, the same laboratory that has
been analyzing samples from St. Louis (93). Preliminary
results are summarized in Table 24.
The fuel analyses for shredded, St. Louis refuse, air
classified and not (Table 20) and for the air classifed
material (Table 24) are not directly comparable. Refuse
varies in composition with season of the year and part
of the country.
87
-------
Table 24
CO
00
Properties of Refuse-Derived Fuel
Dry Weight Basis
|Fuel Value
FUEL BTU/lb.
St. Louis MSW3 6,290
"Eco-fuel-l"b 6,900
RDFC 6,880
RDF, +3/16d 7,855
Paper6 7,500
Coal6 6,500 - 13,000
Composition Wt.%
S
0.2
0.1-0.2
0.2
0.1
0.1
1-5
Cl
0.5
0.1-0.2
0.5
0.5
-
0.05
C
39.6
37.1
43.6
45.4
—
N
0.9
0.8
0.7
0.3
-
ASH
29.4
11.5
22.6
11.3
6.0
8-12
Notes: a. Shredded, but not air classified. Ref. 93
b. Ref. 103
c. Air classified by NCRR. NCRR, unpublished
d. Same as RDF, but the oversize from a 3/16 inch screen. NCRR,
unpubli shed
-------
Generally, air classification slightly increases the
heat value and slightly decreases the ash content (101).
The high ash content of some of the air classified
samples is believed due to glass fines which were pro-
duced in the shredded and carried over with the light
fraction (102). This view is supported by an analysis
of the ash from samples from one city, shown in Table
25. Also shown in Table 25 are similar analyses for
the ash from St. Louis refuse derived fuel delivered
to Union Electric with air classification (96) and the
composition of a typical flint container glass. The ash
compositions, qualitatively, may be viewed as a mixture
of glass, silica, clays, and minor constituents.
The ash content of the Refuse-Derived Fuel in the target
specification (Table 23) is based on experimental results
from several sources, summarized in Table 24. Note,
however, these are preliminary results, except perhaps
for the value for Eco-fuel-I (TM) from a commercial
source (103). The low ash content claimed for this
material, and the experimental result of 11 percent for
one sample, encourages a value of 15 percent ash or lower
in the target specification. Furthermore, a parametric
study of the air classification step and of aerodynamic
means to reduce inorganic fines (102) , also support the
idea of a specification of 15 percent ash.
89
-------
Motes:
Table 25
Composition of Ash from Refuse Derived Fuel*
Si02
A1203
Fe2°3
Ti02
CaO
MgO
Na20
K2O
SO 3
P90c
Ash,
San Antonio
Wt.%
46.10
9.30
7.01
1.11
17.63
1.40
6.01
1.53
7.55
1.50
Ash,
St. Louis0
Wt.T
50.3
11.09
7.76
0.84
12.15
1.28
8.57
1.55
1.45
1.39
Flint
Glass
Wt.%
72.9
1.79
0.036
0.015
11.04
0.66
12.97
0.34
0.20
__
Less than 100 percent of the material is accounted for,
"Single Sample.
cRef. 96
90
-------
There has been concern that the chlorine content of re-
fuse derived fuel is some ten times greater than coal
and because of this, use of RDF will be detrimental to
the operation of power generation boilers. It is
important to point out that most of the chlorides in
RDF may be water soluble (96). Furthermore, most of
the available chlorine in solid waste is not attributable
to any one category of materials in that waste (104).
For example, approximately 36 percent of the chlorine
can be accounted for as from plastics and 28 percent
from paper. Some of this was shown to be water soluble
(104), indicating inorganic chlorine, perhaps from table
salt. If true, this material will be part of the ash
when the fuel is burned and, unlike chlorine from organic
compounds, not necessarily contribute to corrosion of
metallic parts.
The term Refuse-Derived Fuel, or RDF, is used in
the generic sense to indicate any solid fuel prepared
by shredding and air classifying refuse. Air classifier
light fraction may be further processed by chemical and/
or mechanical means to upgrade its fuel properties. The
end products would still be Refuse-Derived Fuels in the
sense the term is used here. The term RDF was, to the
best of our knowledge, coined by Collins (105).
91
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SECTION VI
REFERENCES AND NOTES
(1) Specifications published by the National Association
of Recycling Industries, 330 Madison Ave., New York,
N.Y. 10017.
(2) Paper Stock Standards and Practices. Paper Stock
Institute of America. New York. Circular PS-72.
1972.
(3) C. Lipsett. Industrial Wastes and Salvage. 2nd ed.
New York, Atlas Publishing Company, 1963. 398 p.
(4) Periodic quotations of prices paid according to
grade, form, and local market are quoted in several
publications, such as Iron Age, Official Board
Markets and Waste Trade Journal.
(5) J. Abert and M. Zusman, AIChE J. 18^ (6): 1089-1106,
November 1972; National Center for Resource Re-
covery. Resource Recovery from Municipal Solid
Waste. Lexington, Lexington Books, 1973. 174 p.
(6) Although the tonnage of municipal waste generated
and disposed of each year seems enormous, the
tonnage of recovered materials is apt to be small
(at least for the foreseeable future) compared to
production of new materials which could utilize
scrap. As an example, it has been estimated that
the total quantity of iron and steel in the
municipal waste stream (magnetic metals) is
9,600,000 tons per year (Source: Municipal Solid
Waste - It's Volume Composition and Value, NCRR
Bulletin. 3_ (2): 4-13, Spring 1973.) This is
8 percent of the 120,443,000 tons of domestic
steel production in 1971 (Source: Statistical
Abstract of the United States, 1972.) If as much
as 30 percent of available iron and steel was
92
-------
recovered from municipal solid waste, this would
amount to 2.4 percent of U.S. production. It is
unlikely that this small fraction would be enough
to force large technological change at major steel
producing mills. This is especially true in view
of the fact that approximately 30 percent of
domestic steel tonnage output is accounted for by
scrap consumption now. (Derived from J. H. McGannon.
The Making, Shaping and Treating of Steel. 9th
ed. Pittsburgh, U.S. Steel Co., 1970. p. 254).
(7) National Center for Resource Recovery, Inc.
Materials Recovery System, Engineering Feasibility
Study. Washington, National Center for Resource
Recovery. Inc., 1972. 365 p. Supplement, 1974.
108 p.
(8) In 1971, of 18 composting plants constructed in
the U.S., only 3 were operating on a commercial
basis. (Source: Guidelines for Local Government
on Solid Waste Management. Environmental Pro-
tection Agency. Washington. SW-17c. 1971.)
(9) Resource Recovery Catalogue of Processes. Midwest
Research Institute for the Council on Environ-
mental Quality. Washington. 1973.
(10) F. Wisely, G. Sutterfield and D. Klumb. Use of
Refuse as Fuel in an Existing Utility Boiler.
Combustion. 4_4_ (4) : 38, 1972.
(11) H. Alter. Resource Recovery Cannot be Dependent
on Subsidy. Solid Wastes Management/RRJ. 17
(10): 8, 1974.
(12) A. Darnay and W. Franklin. Salvage Markets for
Materials in Solid Wastes. Environmental Pro-
tection Agency. Washington. SW-29c. 1972.
(13) J.G. Abert, H. Alter and J.F. Bernheisel. The
Economics of Resource Recovery from Municipal
Solid Waste. Science. 183: 1052-1053. 1974,
(14) H. Alter and E.M. Horowitz, eds. Proceedings,
National Materials Conservation Symposium. I.
Resource Recovery and Utilization. Philadelphia,
American Society for Testing and Materials,
1975, in press.
93
-------
(15) First Lesson in Resource Recovery. Envir. Sci
Tech. 71 (4); 300, 1973.
(16) Newspaper Recycling Project Revisited. Public
Works. 104_ (1) : 64, 1973.
(17) E. Graminski in ref. 14.
(18) These are two of the foreign materials which
one of the authors found while picking bundled
newspaper which had been collected from a
residential area. Householders, in their zeal
to package the bundles, seemed inclined to use
whatever was handy to "secure" the newspaper.
(19) Analyses of Wet and Dry Newspaper: Moisture ASTM
D644; water solubles ASTM D1162; organic solubles
ASTM D1804 (not specific for paper); ash ASTM
D586- tensile strength ASTM D828; tear strength
by ASTM D689.
(20) B. Browning. Analysis of Paper. New York, M.
Dekker, 1969. 326 p.
(21) Correlation of Subjective-Objective Methods in
the Study of Odors and Taste. Philadelphia,
American Society for Testing and Materials,
STP 440, June, 1968.
(22) Arrangements for the collection were made by Mr.
W. Rothgeb, Director of Public Works, Rockville,
MD. Arrangements for the tipping were made by
Mr. R. Mangum, Department of Environmental
Services, Montgomery Co., MD.
(23) Baling performed through the courtesy of Mr. P.
Millstone, Montgomery Iron and Metal Company,
Rockville, MD.
(24) Private communication, Mr. J. Weil, Plant
Manager, Johns-Manville Southern Corp., New
Orleans, LA.
(25) As an example of Gillette's background in this
field, see A. Fookson and G. Frohnsdorff. The
Nitrite Accelterated Photochemical Degradation
of Cellulose as a Pretreatment for Microbiological
Conversion to Protein. Gillette Research In-
stitute, Rockville, MD. Contract 68-03-0006.
Environmental Protection Agency. March, 1973.
94
-------
(26) H. Alter, K. Woodruff, A. Fookson, B. Rogers.
The Recovery of Newsprint from Mixed Municipal
Solid Waste. Resource Recovery and Conservation.
In press, 1975.
(27) H. Alter and K. Woodruff. The Particle Size
Distribution of Shredded Refuse for Resource Re-
covery. Resource Recovery and Conservation. In
press, 1975.
(28) Unpublished sampling experience, National Center
for Resource Recovery, Inc. For example, sampling
of household refuse in New Castle Co., DE, in
August, 1972, found 5.7 percent iron and steel
of which 81 percent was classified as packaging
and 19 percent as "other" forms.
(29) Magnetic metals were removed from air classifier
heavy fraction of MSW from St. Louis and New
Castle Co., DE. See also H. Alter, K. Woodruff,
S. Natof, W. Freyberger and E. Michaels. Classi-
fication and Concentration of Municipal Solid
Waste. Fourth Mineral Utilization Conference.
Chicago, U.S. Bureau of Mines and IIT Research
Institute. May, 1974. p. 70-76.
(30) H. McGannon. The Making, Shaping and Treating
of Steel. 9th ed. Pittsburgh, U.S. Steel Co.,
1970. p. 255.
(31) Study of the Economic Viability of Reclaiming
Tin Cans from Solid Waste at a Municipal Transfer
Station. Swindell-Dressier Co. New York, American
Iron and Steel Institute. April, 1972.
(32) E. Ostrowski. Evaluation of Eidal Mill Processed
Solid Waste Ferrous Scrap from St. Louis, Missouri
Solid Waste Recovery System. Weirton, National
Steel Co. January 7, 1973. p. 17.
(33) Metals Handbook, Properties and Selection of
Metals. 8th ed. Vol. 1. Metals Park, Ohio
American Soc. for Metals, 1969.
(34) W. Hogan. Durable Goods and Steel, the 1970's:
Crisis for Steel. American Metal Market. May
29, 1973. p. 9.
(35) J. Szekely, ed. The Steel Industry and the Environ-
ment. New York, M. Dekker, Inc., 1973. 278 p.
95
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(36) Reference 33, op cit.
(37) Personal communication, W. Malby, Aluminum Company
of America.
(38) H. Cannon. Can We Recycle Cans. Technology Rev.
74_ (6) : 40, 1972.
(39) E. Ostrowski. Recycling of Tin Free Steel Cans,
Tin Cans and Scrap from Municipal Incinerator
Residue. National Steel Co. (Presented at 79th
General Meeting, American Iron & Steel Institute.
New York. May 26, 1971.)
(40) Containers and Packaging. Washington, U.S. Dept.
of Commerce. July, 1972. p. 23.
(41) Derived from figures reported in reference 40.
(42) Ibid., p. 23, 26.
(43) E*. Ostrowski. Recycling of Tin Free Steel Cans,
Tin Cans and Scrap from Municipal Incinerator
Residue. Iron & Steel Engr. July, 1971, p. 74.
(44) Operating practices described to authors by several
steel company representatives.
(45) R. Kaplan in reference 14.
(46) Meeting with E. Ostrowski, National Steel Re-
search, Weirton, W. Va., June 13, 1972.
(47) Personal communication, E. Mallick, U.S. Steel
Co., November 13, 1972.
(48) Personal communication, F. Weise, Florida Steel
Co., October 27, 1972.
(49) J. Richards and J. Hornack. U.S. Steel Corporation's
First Ingot Free Electric and Furnace Steel Melting
Shop. Iron & Steel Engr. 48; 381, 1971.
(50) Personal communication, Mr. G. McCauslan, M&T
Chem. Co., July 26, 1972.
(51) Ibid., August 30, 1972.
(52) Copper Industry Uses Much Scrap Iron. Envir. Sci.
Tech. 4_ (2) : 100, 1973.
96
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(53) Personal communication, Mr. M. L. Smith, Continental
Can Co., June 14, 1972.
(54) C. Loper, P. Rosenthal, et. al. Recycling Municipal
Scrap Metal - A MetallurgTca3T~Problem. Madison,
Univ. Wisconsin, Department of Metallurgical and
Mineral Engr. Undated.
(55) Personal communication, Mr. I. Proler, Proler
International. November 13, 1972.
(56) A. Darnay and W. Franklin, ref. 12, p. 54.
(57) T. Willson. Amer. Iron & Steel Inst. (.Presented
at Amer. Soc. for Testing and Materials.
Philadelphia. November 14, 1972.)
(58) K. Van Horn. Aluminum. Vol. I, Properties,
Physical Metallurgy and Phase Diagrams. Metals
Park, Amer. Soc. for Metals, 1968. 425 p.
(59) Alcoa Aluminum Handbook. Pittsburgh, Aluminum
Co. of America, 1967. 296 p.
(60) Aluminum Association, 420 Lexington Ave., New
York, N.Y.
(61) Personal Communication, R. Cooperman, Aluminum
Recycling Association, September 24, 1974.
(62) Determined by NCRR sampling program, 1972.
Unpublished.
(63) Meeting with research personnel, Aluminum Co.
of America, Merwin, Pennsylvania, September 1,
1972.
(64) Personal communication, R. Testin, Reynolds
Metals Co., October 9, 1972.
(65) Analyses by L. Blayden, Aluminum Co. of America,
April 18, 1973.
E. L. Michaels, K. Woodruff, W. Freyberger and
H. Alter. Heavy Media Separation of Aluminum
from Municipal Solid Waste. Trans. AIME. 1975.
In press.
97
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(67) L. Blayden. Composition Control - Key to Recycling
Aluminum. Alcoa. (Presented at Society of Mining
Engineers, 103rd annual meeting. Dallas. February
28, 1974.)
(68) H. Makar in ref. 14.
(69) C. Kenahan, P. Sullivan, J. Ruppert and E. Spano.
Composition and Characteristics of Municipal
Incinerator Residues. RI 7204. Bureau of Mines.
1968. 20 p.
(70) H. Alter. Science 183: cover, March 15, 1974.
(71) Personal communication, G. Sequin, Huron Valley
Steel Co., Detroit, T. Dudda, Luria Bros., Cleveland,
L. McCarthy, Newell Industries, San Antonio, J.
Diefenthal, Southern Scrap Materials Co., New
Orleans, and others.
(72) Utilization of Waste Glass in Secondary Products.
Proc. of Conf., Technology Applications Center.
Albuquerque, Univ. New Mexico, January, 1973. 361 p.
(73) Kirk-Othmer. Encyclopedia of Chem. Tech. 2nd ed.
New York, J. Wiley, 1966. Vol. 10 p. 533-604.
(74) Personal communication. J. Cummings, Owens-Illinois
Corp., July 19 and October 6, 1972.
(75) C. Seeley in ref. 14.
(76) Evaluation of U.S. Bureau of Mines Reclaimed
Glass Fraction in Glass Container Manufacturing
Process. Anchor Hocking Co. Lancaster. Undated
but transmitted to authors January 10, 1972.
(77) P. Scott in ref. 14.
(78) J. Cummings. Glass and Aluminum Recovery Sub-
system - Franklin, Ohio. Proc. of the Fourth
Mineral Waste Utilization Symposium. Chicago.
U.S. Bureau of Mines and IIT Research Institute.
1974. p. 106-115.
(79) M. Tyrell and A. Goode. Waste Glass as a Flux for
Brick Clays. RI 7605. Bureau of Mines. 1972.
98
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(80) GCMI Guideline Specifications for Soda-Lime Con-
tainer Glass Gullet. Environmental Pollution
Control Committee. Glass Container Manufacturers
Institute, Inc. Washington. 1972.
(81) Letter of Intent for the purchase of recovered
cullet from R. J. Lanigan, Owens-Illinois Corp.
to H. Alter, National Center for Resource Recovery,
February 22, 1973.
(82) P. Stanczyk and P. Sullivan. Electric Color Sorting
of Glass from Urban Waste. TPR 45. Bureau of
Mines. October 1971.
(83) M. Stewart. Beneficiation of Glass-Rich Fractions
from Municipal Solid Waste Systems by Dense Media
Separation. Project 84, Owens-Illinois for Glass
Container Manufacturers Institute, Inc. Washington.
October 1972.
(84) A. Gaudin. Principles of Mineral Dressing. New
York. McGraw-Hill, 1939. p. 310-312.
(85) O. Bowles. Slate Dust in Asphalt Road Surface
Mixtures. 1C 2230. Bureau of Mines. 1921.
(86) W. Malish, T. Keith, et. al_. Effect of Contaminants
in Recycled Glass UtiTTzed for Glasphalt. Proc.
Third Mineral Waste Utilization Symposium. Chicago.
IIT Research Institute and Bureau of Mines. 1972.
(87) E. Elton. Porous Concrete for Tree Wells. Public
Works. 103 (10): 99, 1972.
(88) Meeting with three members of ASTM Committee U-4,
Road and Paving Materials, April 13, 1972.
(89) J. J. Emery. Waste and By-product Utilization
in Highway Construction. Resource Recovery and
Conservation. 1975. In press.
(90) Personal communication, P. Cramp, National Bureau
of Standards, June 28, 1973.
(91) National Center for Resource Recovery. Resource
Recovery from Municipal Solid Waste. Lexington.
Lexington Books, 1973. p. 143-146.
99
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(92) Uorwalk CN Recycling Plant. Grant Application
to U.S. Environmental Protection Agency. July
31, 1972.
(93) Solid Waste Disposal Seminar, Proceedings. St.
Louis. Union Electric Co., 1972.
(94) D. L. Klumb. Ibid, p. V-l - V-12.
(95) R. A. Lowe. Energy Recovery from Waste, SW-36d.
ii. Environmental Protection Agency. Washington.
1973.
(96) D. Klumb, Union Electric Co. Private communication.
1974.
(97) J. Leonard and D. Mitchell. Coal Processing. New
York. The Amer. Inst. of Mining, Metallurgical
and Petroleum Engr., 1969. p. 1-4.
(98) Analyses by methods described in ASTM D271.
(99) J. Polich and H. Hollander. Preliminary Evaluation
of Community Solid Wastes Utilized as Salvage
Cubettes for Municipal Electric Generation. Roy
F. Weston. Ft. Wayne. City of Ft. Wayne. 1971.
(100) Private communication, B. Michaels, General Motors
Corp., 1973.
(101) H. Alter and H. Sheng. Energy Balances for
Recovery of Materials and Refuse Derived Fuel.
Resource Recovery and Conservation. 1975.
In press.
(102) D. M. Fan. On the Air Classified Light Fraction
of Shredded Municipal Solid Waste: I. Composition
and Physical Characteristics. Ibid.
(103) Combustion Equipment Associates, Inc. 555 Madison
Ave., New York, H.Y. 10022.
(104) H. Alter, G. Ingle and E. Kaiser. Chemical
Analyses of the Organic Portions of Household
Refuse; The Effect of Certain Elements on In-
cineration and Resource Recovery. Solid Wastes
Management (London.) December, 1974. In press.
(105) J. F. Collins, New York State Environmental
Facilities Corporation. 1973.
100
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SECTION VII
PUBLICATIONS
The National Center for Resource Recovery, Inc. has a major
goal — "research, analysis, and dissemination of infor-
mation" -- regarding municipal solid waste. In keeping
with its objectives, NCRR published a 367-page report in
December, 1972 titled "Materials Recovery System, Engi-
neering Feasibility Study" (7). Chapter five of the report,
"Output Characteristics," contained preliminary specifi-
cations for recovered materials which were developed con-
currently with research on this project.
Other publications based, in part, on work performed under
the research grant reported here, are:
E. L. Michaels, K. L. Woodruff, W. L. Freyberger,
H. Alter, "Heavy Media Separation of Aluminum from
Municipal Solid Waste," paper presented at the AIME
103rd Meeting, February, 1974, Transactions AIME,
in press.
H. Alter and K. L. Woodruff, "Particle Size Distri-
butions of Shredded Refuse; Processing for Resource
Recovery," Resource Recovery and Conservation, in
press.
H. Alter, K. L. Woodruff, A. Fookson, B. Rogers,
"Analysis of Newsprint Recovered from Mixed Municipal
Solid Waste,1: Resource Recovery &^ Conservation, in press
H. Alter, S. Natof, K. L. Woodruff, E. L. Michaels,
W. L. Freyberger, "Classification and Concentration
of Municipal Solid Waste," Proc, 4th Mineral Waste
Utilization Symp., 1974, pp. 76-79.
101
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SECTION VIII
APPENDIX
Representative Specifications Now Used In The Scrap
Industry
102
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Explanation of Terms Used
In ISIS* Specifications
a. Cleanness. All grades shall be free of dirt, non-
ferrous metals, or foreign material of any kind, and
excessive rust and corrosion. However, the terms
"free of dirtr nonferrous metals, or foreign material
of any kind" are not intended to preclude the acci-
dental inclusion of negligible amounts where it can
be shown that this amount if unavoidable in the
customary preparation and handling of the particular
grade involved.
b. Off-grade material. The inclusion in a shipment of
a particular grade of iron and steel scrap of a
negligible amount of metallic material which exceeds
to a minor extent the applicable size limitations,
or which fails to a minor extent to meet the appli-
cable requirements as to quality or kind of material,
shall not change the classification of the shipment,
provided it can be shown that the inclusion of such
off-grade material is unavoidable in the customary
preparation and handling of the grade involved.
c. Residual alloys. Wherever the term "free of alloys"
is used in the classifications given herein, it
shall mean that any alloys contained in the steel are
residual and have not been added for the purpose of
making an alloy steel. Steel scrap shall be con-
sidered free of alloys when the residual alloying
elements do not exceed the following percentages:
percent
Nickel 0.45
Chromium 0.20
Molybdenum 0.10
Manganese 1.65
The combined residuals other than manganese shall
not exceed a total of 0.60 percent.
d. Deviations. Any deviations from the general classi-
fications of iron and steel scrap may be consummated
by mutual agreement between buyer and seller.
*Source: Institute of Scrap Iron & Steel, Inc.
1729 H Street, N.W.
Washington, D.C. 20006
103
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Accepted Specifications For Selected
Remelting Grades of Steel Scrap
BASIC OPEN HEARTH, BASIC OXYGEN,
ELECTRIC FURNACE, AND BLAST
FURNACE GRADES
Shredded Tin Cans For Remelting Shredded 213
Steel cans, tin coated or tin free, may
include aluminum tops but must be free
of aluminum cans, nonferrous metals
except those used in can construction,
and non-metallics of any kind.
Bundled No. 1 Steel. Wrought iron and/ 217
or steel scrap 1/8 inch or over in
thickness, compressed to charging box
size and weighing not less than 74
pounds per cubic foot. Free of all
metal coated material.
Bundled No. 2 Steel. Wrought iron or 218
steel scrap, black or galvanized, 1/8
inch and over in thickness, compressed
to charging box size and weighing not
less than 75 pounds per cubic foot.
Auto body and fender stock, burnt or
hand stripoed, may constitute a max-
imum of 60 percent by weight. (This
percent based on makeup of auto body,
chassis, driveshafts, and bumpers.)
Free of all coated material, except
as found on automobiles.
Source: Institute of Scrap Iron & Steel, Inc.
1729 H Street, II.W.
Washington, D.C. 20006
104
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UNITED STATES STEEL CORPORATION
OPEN HEARTH CARBON STEEL SCRAP SPECIFICATIONS
All grades must be free of alloy and stainless scrap,
non-ferrous metals, closed containers, or foreign material
of any kind and free of excessive dirt, rust, corrosion,
paint, grease and oil.
1. No. 1 Bundles. New black carbon steel sheet scrap,
clippings, or skeleton scrap, hydraulically compressed
or hand bundled to charging box size and weighing
not less than 75 pounds per cubic foot. (Hand bundles
must also be tightly secured and stand handling with
a magnet). Must be free of paint or protective coat-
ing of any kind. May include mandrel wound bundles
or skeleton reels, tightly secured. Must not in-
clude turnings, beadwire, electrical sheets or any
material over 0.5% of silicon.
2. No. 1 Heavy Melting Steel. Clean wrought iron or
carbon steel scrap 1/4 inch and over in thickness,
not over 18 inches in width and not over 5 feet in
length. Individual pieces must be free from attach-
ments , and so cut as to lie flat in the charging
box. May include new mashed pipe ends, 4 inches and
over Must not include cast iron, malleable iron,
boiler tubes, fire boxes, burnt boiler plate, anneal-
ing boxes, welding rods, pit scrap, slag, skulls,
spills, runouts or similar material.
3. No. 1 Busheling. Clean new carbon steel scrap 1/16
inch and over in thickness, not exceeding 12 inches
in any dimension, including new factory busheling
20 gauge or heavier (for example, sheet clippings,
stampings, etc.). May not contain burnt material
or auto body and fender stock. Must be free of
metal coated, limed or porcelain enameled stock.
4. No. 2 Heavy Melting Steel. Wrought iron or carbon
steel scrap, black or galvanized, 1/8 inch and over
in thickness, not over 18 inches in width and not
over 3 feet in length. Individual pieces must be
105
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free from attachments and so cut as to lie flat
in charging box. May include pipe 4 inches and
under in diameter, cut 3 feet or less. Must not
include automobile body and fender stock, cast
iron, malleable ironr boiler tubes, fire boxes,
burnt boiler plate, annealing boxes, welding rods,
pit scrap, slag, skulls, runouts or similar
material.
5. No. 2 Bundles. Body and fender carbon steel scrap,
or old black and/or galvanized carbon steel scrap,
hydraulically compressed to charging box size and
weighing not less than 75 pounds per cubic foot.
Must not include turnings, beadwire, vitreous
enameled stock, tin cans, tin plate, terne plate or
other metal coated material. Painted or lacquered
material shall not be considered as metal coated
material. Must be free of rubber, wood and copper,
including BX cable stripped and unstripped. May
include hydraulically compressed black or galvanized
fence wire and light coil springs.
6. No. 3 Bundles. Off-grade material, compressed to
charging box size and weighing not less than 75
pounds per cubic foot. May include completely
stripped BX cable. May include galvanized, vitreous
enameled and other coated ferrous scrap not suitable
for inclusion in No. 2 Bundles, except tin and
terne coated material which are not acceptable. Must
be free of dirt, rubber, wood, non-ferrous metals,
tin cans, and non-metallics of any kind.
7. Incinerator Bundles. Tin can scrap, compressed to
charging box size and weighing not less than 75
pounds per cubic foot. Must have been processed
through a recognized garbage incinerator, must be
free of dirt, non-ferrous metals and non-metallics
of aivy kind.
United States Steel Corporation
Purchasing Division
August 18, 1970
106
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UNITED STATES STEEL CORPORATION
ELECTRIC FURNACE SCRAP SPECIFICATIONS
All scrap must not contain over 0.05% phosphorous or
sulphur, and not over 0.5% silicon and free of all alloys
1. Billet Bloom and Forge Crops. Must be new material
not less than 2 inches in thickness and not over
18 inches in width and 36 inches in length.
2. Bar Crops and Plate Scrap. Must be new material
not less than 1/4 inch in thickness and not over
18 inches in width and 36 inches in length.
3. Cut Structural and Plate Scrap. Clean, new, open
hearth steel plates and structural shapes, crop ends,
shearings, must not be less than 1/4 inch in thick-
ness nor over 18 inches in width and 36 inches in
length.
4. Flashings. Clean, new, cut flashings at least 1/4
inch in thickness in body of flashing and cut not
to exceed 12 inches in width and 24 inches in length.
Uncut flashings not acceptable.
United States Steel Corporation
Purchasing Division
August 18, 1970
107
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Accepted Specifications
For Selected Grades
Of Scrap Aluminum
Code
Take 75
Talc 75
Tall 80
Tense 86
Testy 89
Item Description
NEW ALUMINUM CAN STOCK
Shall consist of new low copper
aluminum can stock and clippings,
clean, lithographed or not li-
thographed, and coated with clear
lacquer but free of lids with
sealers, iron, dirt and other
foreign contamination. Oil not
to exceed 1%.
OLD CAN STOCK
Shall consist of clean old alumi-
num cans decorated or clear, free
of iron, dirt, liquid and/or other
foreign contamination.
E. C. ALUMINUM NODULES
Shall consist of clean E. C. alumi-
num, chopped or shredded, free of
screening, hair-wire, iron, in-
sulation, copper and other foreign
contamination. Must be free of minus
20 mesh material. Must contain
99.45% aluminum content.
MIXED ALUMINUM CASTINGS
Shall consist of clean, new, pure,
uncoated, unalloyed aluminum foil,
free from anodized foil, radar
foil and chaff, paper plastics,
or any other foreign materials.
Hydraulically briquetted material
by arrangement only.
OLD ALUMINUM FOIL
Shall consist of clean, old, pure,
uncoated, unalloyed aluminum foil,
free from anodized foil, radar
foil and chaff, paper, plastics,
or any other foreign materials.
Hydraulically briquetted material
by arrangement only.
108
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Thigh 90
Throb 92
Tooth 93
Tough 94
ALUMINUM GRINDINGS
Should be sold on recovery basis
or by special arrangements with
purchaser.
SWEATED ALUMINUM
Shall consist of aluminum scrap which
has been sweated or melted into a
form or shape such as an ingot, nig
or slab for convenience in shipping;
to be free from corrosion, drosses
or any foreign materials. Should
be sold subject to sample analysis.
SEGREGATED NEW ALUMINUM ALLOY
CLIPPINGS AND SOLIDS
Shall consist of new, clean, uncoated
and unpainted aluminum scrap of one
specified aluminum alloy only and to
be free of foil, hair wire, wire
screen, dirt, and other foreign
substances. Oil and grease not to
total more than 1%. Also free from
punchings less than 1/2% in size.
New cab stock subject to arrangement
between buyer and seller.
MIXED NEW ALUMINUM ALLOY CLIPPINGS
AND SOLIDS
Shall consist of new, clean, un-
coated and unpainted aluminum scrap
of two or more alloys free of 70S
series and to be free of foil,
hair wire, wire screen, dirt and
other foreign substances. Oil
and grease not to total more than
1%. Also free from punchings
less than 1/2" in size. New Can
Stock subject to arrangement be-
tween buyer and seller.
Source: Standard Classification for Nonferrous Scrap
Metals, Circular NF-73, National Association
of Recycling Industries, 330 Madison Ave.,
New York, New York 10017.
109
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-670/2-75-034
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
SPECIFICATIONS FOR MATERIALS RECOVERED
FROM MUNICIPAL REFUSE
5. REPORT DATE
May 1975; Issuing Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
H. Alter and W. R. Reeves
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
The National Center for Resource Recovery,
1211 Connecticut Avenue, N.W.
Washington, D.C. 20036
Inc
10. PROGRAM ELEMENT NO.
1DB314; ROAP 06AKO; Task 02
11. (XJBOBOHC/GRANT NOT
801622
12. SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
PROJECT OFFICER: Carlton Wiles 513/684-4484
16. ABSTRACT
Specifications presented in this report represent first efforts to
define uniform qualities of materials separated from municipal solid
waste in resource recovery processing plants for subsequent sale and
use. The establishment of specifications adds value to outputs and
promotes acceptance by users as a result of providing a basis for
quality assurance. Recoverable materials investigated in this study
are: folded newsprint and corrugated paper, ferrous metals, aluminum,
other nonferrous metals, glass cullet, inorganic fines, mixed organics
(for fuel). Indications of possible contamination were obtained on a
limited scale by reviewing literature, visiting plants, and coordi-
nating with the activities of a companion research grant which included
processing pilot quantities of municipal solid waste from several
cities. The resulting target specifications were written as goals for
plant design; the targets seem achievable with existing technology.
The likelihood of these target specifications being accepted was
checked by reviewing them with officials of appropriate companies and
trade associations.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Refuse
Reclamation
Materials recovery
*Materials specifications
Solid waste separa-
tion
Refuse materials
recovery
Secondary materials
*User specifications
13B
8. DISTRIBUTION STATEMEN1
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF PAGES
120
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
110
60K«IUIE«
975-6S7-593/5376 Real on No. 5-11
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