United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-83-094 Dec. 1983
SER& Project Summary
Alternate Treatment of Organic
Solvents and Sludges from
Metal Finishing Operations-
Final Report
S.C. Cheng, T.E. Ctvrtnicek, B.O. Desai, C.S. Smith, H.D. Toy, and W.H. Medley
The objectives of this study were to
(1) describe the metal finishing industry
and its use of organic materials, (2)
describe the quantity and composition
of organic wastes from metal finishing,
(3) describe the current technologies
used to recover and dispose of these
materials, and (4) draw conclusions and
make recommendations on future work
which needs to be done to improve
ways to reuse or dispose of organic
residues from metal finishing operations.
The metal finishing industry uses
significant amounts of organic mater-
ials in its metal working processes, in
solvent cleaning, and in product coating
processes. Data on the quantities and
compositions of these wastes were
collected from literature sources,
industry sources, and state and environ-
mental agency files. Processes for
handling these wastes were described
and recommendations were made for
future work to promote the safe
disposal of these organic residues.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory, Cincinnati. OH, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Industry Description
Metal Finishing
There are approximately 150,000
industrial plants in the United States in
SIC Codes 25 and 33-39 which comprise
the metal finishing industry.
This study of the metal finishing
industry focused on processes which use
significant amounts of organic materials.
These are (1} the metalworking processes,
(2) solvent cleaning, and (3) product
coating processes. Metalworking pro-
cesses are of four types: (1) metal
removal, (2) metal forming, (3) heat
treating, and (4) rust preventive coating.
Specific processes included are listed in
Table 1.
Some metal finishing processes, such
as electroplating, primarily use inorganic
materials. Examples of these processes,
which are excluded from this study, are
also shown in Table 1.
Metal cutting operations, such as
machining, require oils both as lubricants
and coolants. Emulsified oils or soluble
synthetic fluids are sold as concentrates,
then diluted with water before use. Metal
forming operations use oils primarily for
lubrication.
The hot- and cold-rolling operations
used for production of steel and aluminum
strip and sheet use many different types
of oils. Heat treating operations, such as
quenching, use mineral and emulsified
oils to quickly reduce metal temperatures.
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Table 1. Process Categorization
Forming processes
Molding
Casting
Shaping
Extruding
Abrasive processes
Cutting
Boring
Grinding
Milling
Tumbling
Electroplating
Etching
Acid pickling
Anodizing
Bright-dipping
Passivating
Chromating
Phosphating
Plastic coating
Ceramic coating
Immersion plating
Galvanizing
Conversion coating
Alloying
Processes Included in Study _
Drawing
Rolling
Stampling
Blasting
Buffing
Deburnng
Polishing
Processes Excluded from Study
Cleaning processes
Solvent cleaning
Degreasing
Coating processes
Painting rust prevention
Rust prevention
Heat-treating processes
Quenching
Tempering
Surface preparation
and post-treatment,
including
Acid cleaning
Alkaline cleaning
Chemical machining
Chemical mi/ling
Chemical polishing
Chemical etching
Straight mineral oils are used to coat
steel coil as a rust preventive.
Degreasing or solvent metal cleaning
uses nonaqueous solvents to clean
surfaces of all of the common ferrous and
nonf errous metals. The four main types of
organic solvents used for solvent metal
degreasing operations are: alcohols,
halogenated solvents, hydrocarbons, and
ketones.
Paints are classified in two major
categories, as solvent-based or water-
borne paints. The water-borne paints
were developed to decrease the total
amount of volatile solvent emissions and
are widely used as product coatings.
However, solvent-borne enamels and
lacquers remain the most widely used in
the automotive industry. Six major
methods are used for the application of
product coatings in the metal finishing in-
dustry: (1) spray painting, (2) dip coating,
(3) flow coating, (4) roll coating, (5) elec-
trodeposition, and (6) powder coating.
The purposes of this study were (1) to
describe the metal finishing industry and
its use of organic materials, (2) to
describe the quantity and composition of
organic wastes from metal finishing, (3)
to describe the current technologies used
to recover or dispose of these materials,
and (4) to draw conclusions and make
recommendations as to future work that
needs to be done to improve reuse and
disposal of organic residues from the
metal finishing industry.
Organic Wastes
The annual quantities of organic
materials used in metal finishing, the
amounts of organic waste currently
collected, and the estimated amounts
that could be collected are shown below.
The oils may be petroleum-based
mineral oils (used straight), emulsified
oils, or synthetic oils. Commonly used
additive types include anti-oxidants, rust
preventatives, extreme pressure additives,
viscosity index improvers, pour point
depressants, fatty oils, and emulsifiers.
Waste mineral oils may contain sulfur,
chlorine, fluorides, nitrogen, phosphates,
metal chips and fines, sediment, water,
PCBs, oxidation products, and phenolic
compounds as contaminants.
Waste emulsified and synthetic oils
may contain metal particles, biodegrada-
tion products, tramp oil, nitrosamines,
and residues from oil additives —
including sulfur, phosphorus, chlorine,
zinc, lead, copper, and phenolic com-
pounds — as contaminants.
The waste solvents maybe halogenated
or nonhalogenated and may contain oil,
grease, wax, metallic particles, etev-^
Waste coating may contain high
concentrations of organic solvents,
resins, and heavy metals.
Recovery and Disposal
Environmental regulations usually
prohibit the discharge of untreated
organic wastes from the metal finishing
industry into surface waters because
they contain unallowable concentrations
of both organic and inorganic pollutants.
With increasingly restrictive environ-
mental regulations, disposal of waste oils
is becoming expensive. Therefore, refin-
ing/reclamation/alternate applications
are viable options for waste oil generators.
Refining/reclamation technology for
waste straight oils is well developed.
Independent re-refiners accept waste oils
for refining based on their composition
and compatibility with refining technology
used in their plants.
Waste emulsified oil treatment reclama-
tion technology has been well developed
in recent years. Economics of on-site or
off-site treatment or disposal for a plant
will depend on the volume of waste
emulsified oil generated. Larger plants
generally treat their waste prior to
discharging wastewater to surface
waters. Smaller plants exercise off-site
treatment or disposal options. It is
possible that some plants might still be
illegally disposing of waste emulsified oil
into sewers. The use of regional facilities
to treat waste emulsified oils from small
plants has been considered.
Synthetic fluids are expensive, so fluid
maintenance and management programs
in the plant are utilized to increase fluid
life expectancy. Very limited technology
is available at present to reclaim spent
synthetic fluids. Synthetic fluids manu-
facturing firms are developing water
soluble biodegradable synthetic fluids to
Use
Metalworking (oils)
Degreasing (solvents)
Product coatings (paints)
TOTAL
Annual
consumption,
106 kg/yr
760
670
1,050
2,480
Waste
collected,
10s kg/yr
180
580
200
960
Waste
potentially
collectable,
10e kg/yr
48O
630
200
1.310
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avoid costly disposal problems. Disposal
alternatives and costs are highly depen-
dent on the chemical formulations of
synthetic fluids, which are generally
treated as proprietary information. For
this reason, very limited information is
available about treatment or disposal of
spent synthetic fluids.
Waste solvents have high potentials for
recovery and reuse. Also the Resource
Conservation and Recovery Act (RCRA)
lists waste solvents as hazardous waste,
so they are to be disposed of in accordance
with the regulations.
Reclamation technology for waste
solvents is well developed. Due to RCRA
regulations, disposal of waste solvents is
becoming very expensive. For this reason
more generators are starting to use the
services of waste solvent reclaiming
firms. Waste solvent reclaiming firms
have been growing in number since
RCRA regulations came into effect.
The major application method contri-
buting to paint waste is the spray coating
method. The waste is almost exclusively
disposed of in either sanitary or secured
landfills. A very small portion is incinerated.
Paint wastes have limited recovery or
reuse potential. Waste coating may or
may not be a hazardous waste depending
on its composition. The disposal practice
will depend on whether the waste is
hazardous or nonhazardous. RCRA
testing will be required to classify a waste
coating as hazardous or nonhazardous.
Conclusions
From this work it was concluded that:
(1) The 150,000 metal finishing plants
in the United States use 2,480
million kilograms of organic mater-
ials per year
(2) At present approximately 40 percent
of these materials are collected for
reclamation or disposal by processes
such as incineration, landfill, or
use in road paving. The other 60
percent which is not collected, is
disposed of by processes such as
vaporization losses, process losses
on-site, and dumping.
(3) The metal finishing industry is
concentrated in ten heavily industri-
alized states. California, Illinois,
New York, Ohio, Michigan, Pennsyl-
vania, Texas, New Jersey, Massa-
chusetts, and Indiana (in order of
number of large plants).
(4) These states are the ones with the
most potential for setting up reclama-
tion centers since they generate
the largest amount of wastes.
(5) The organic wastes from the metal
finishing industry come primarily
from the metalworking, solvent
cleaning, and product coating pro-
cesses.
(6) The wastes from the metalworking
and solvent cleaning processes
generally contain sufficient concen-
trations of organic or inorganic
contaminants to make them envi-
ronmentally unacceptable for dis-
charge to surface waters without
treatment.
(7) Paint wastes vary from innocuous to
hazardous; hence, decisions must
be made on each one individually to
determine whether or not there are
restrictions on the manner in which
they are disposed of.
(8) Waste oil compositions vary consid-
erably, depending upon their initial
composition, the process in which
they are used, the severity of the
operating conditions (temperature
and pressure), and the degree of
recycle or reuse.
(9) Waste mineral oil refining and
reclamation technology is well
developed technically, but its
economic practicality is in question.
At present only a small fraction of
the oil which could be re-refined is
processed for reuse. The relatively
small volume of oil being processed
and its fluctuating quantities produce
uncertainty in the economic viability
of this approach. As long as there
are few regulations requiring or
strongly encouraging re-refining, it
will continue to be a solution for only
a small fraction of oil disposal
problems.
(10) The costs of disposing of waste oil
are increasing, making re-refining
or reclamation more attractive
economically.
(11) High-priced synthetic metalworking
fluids are increasingly used in the
industry. The recovery potential for
synthetic fluids is unknown at
present.
(12) Few reclaimers handle waste oil
water emulsions, or synthetic or
water-based metal working fluids.
(13) Solvent recovery is handicapped by
the diversity of solvents available
and the small quantities of specific
solvents at some locations. Some
solvent recovery companies are not
well qualified, and they are frequently
underfinanced.
(14) Some solvents are complex mixtures
of chemicals that are difficult to
recycle.
(15) Disposal companies are basically
incinerating waste solvents at high
cost. Disposal costs are so high that
waste solvent generators are reluc-
tant to call them.
(16) Most solvent recyclers only process
a limited number of solvents. They
may not provide a service to many
small waste solvent generators.
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S. C. Cheng. T. E. Ctvrtnicek, B. O. Desai, C. S. Smith. H. D. Toy. and W. H. Medley
are with Monsanto Research Corporation, Dayton. OH 45407.
Alfred B. Craig, Jr., was the EPA Project Officer (see below for present contact).
The complete report, entitled "Alternate Treatment of Organic Solvents and
Sludges from Metal Finishing Operations—Final Report," (Order No. PB 84-102
151; Cost: $28.00. subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
For information contact S. Gary Howell at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
6US GOVERNMENT PRINTING OFFICE 1983-659-017/7238
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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