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The Micronytrii
Industry:
Byproduct
confaihing at least 30% postconsumer recovered fiber.
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The Micronutrient Fertilizer Industry:
From Industrial Byproduct to Beneficial Use
Office of Compliance
Office.of Enforcement and Compliance Assurance
U.S. Environmental Protection Agency
Washington, D.C. 20004
September 2001
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'Disclaimer
The U.S. Environmental Protection Agency (EPA) has reviewed this document and approves it for
publication. This document does not constitute rulemaking by the EPA and may not be relied on to
create a substantive or procedural right or benefit enforceable at law or in equity, by any person. The
EPA may take actions at variance with this document and its internal procedures.
Disclaimer
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Table of Contents
Page
1.0 Purpose of Report - 1-1
2.0 Overview of the Micronutrient Fertilizer Industry , . . . . 2-1
2.1 Classes of Micronutrients 2-1
2.2 Industrial Byproducts Used in Micronutrients . 2-1
2.3 General Micronutrient Fertilizer Production Overview . 2-3
3.0 Industrial Sources of Zinc-Bearing Byproducts 3-1
3.1 Steel Manufacturing: Electric Arc Furnace Dust (K061) 3-2
3.2 Brass Smelters and Foundries: Brass Fume Dust (D006, D008) 3-4
3.3 Tire Incineration for Energy Recovery: Tire Ash (D006, D008) 3-6
3.4 Galvanizing Operations: Zinc Dross and Skimmings and Spent Acids 3-6
4.0 Processing/Recovery of Zinc Micronutrients 4-1
4.1 Zinc Sulfate . 4-1
4.2 Zinc Oxysulfate . . . . 4-2
4.3 Ammoniated Zinc Sulfate ........ 4-3
4.4 Zinc Chloride .-"... 4-3
4.5 Zinc Oxide : . . 4-4
5.0 Product Formulation 5-1
5.1 Liquid Formulating 5-1
5.2 Dry Formulating 5-2
6.0 Land Application of Zinc Micronutrients 6-1
6.1 Application Methods 6-1
6.2 Application Concentrations and Exposures 6-3
7-0 Overview of Existing Regulations 7-1'
7.1 Resource Conservation and Recovery Act (RCRA) 7-1
7.2 Hazard Communication Standard 7-7
7.3 State Regulations 7-7
7.4 International Regulations.' 7-9
8.0 References. . 8-1
'V*: "
Table of Contents
i*
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List of Tables
Page
2-1 Industrial Byproduct Sources for the Top Micronutrients in Use in the U.S. ........ 2-2
3-1 Industrial Byproducts Most Commonly Used in Zinc Micronutrient Fertilizers 3-1
3-2 Comparative Chemical Composition of Dust from EAPs 3-3
4-1 Sample Results for Zinc Sulfate Monohydrate Micronutrient Products 4-2
4-2 Sample Results for Zinc Oxysulfate Micronutrient Products 4-4
6-1 Sources of Zinc Used for Land Application 6-3
6-2 Information For Applying Zinc Micronutrient Fertilizers Using Band and
Broadcast Procedures 6-4
7-1 Washington Standard for Annual Metal Additions to Soil "... 7-8
7-2 State of Texas Limitations for Commercial Fertilizers ' 7-9
7-3 Canadian Maximum Acceptable Cumulative Metal Additions to Soil
and Maximum Acceptable Metal Concentration in Products 7-10
List of Tables
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List of Figures
Page
2-1 Overview of Micronutrient Production 2-3
3-1 Electric Arc Furnace Steel Manufacturing 3-2
3-2 Brass Smelting Process : . 3-4
3-3 Brass Foundry Processing .3-5
3-4 Hot-Dip Zinc Galvanizing Process ' 3-7
4-1 Zinc Sulfate Manufacturing . . . 4-1
4-2 Zinc Oxysulfate Manufacturing 4-3
5-1 Typical Liquid-Based Formulating Line 5-1
5-2 Typical Granular Formulating Line 5-2
5-3 Typical Dry Spray-Coated Formulating Line 5-2
6-1 Broadcast Spreading 6-1
6-2 Band Application 6-2
6-3 Injection .' 6-2
6-4 Fertigation 6-2
- I
List of Figures
ff~
t
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Acknowledgment
The U.S. EPA would like to thank Dr. Charles W. Perry for his technical assistance during the prepa-
ration of this compliance assistance manual. Dr. Perry was employed in the Office of Compliance
under the Senior Environmental Employee Program during the development of this manual when he
held the nationwide distinction of having the longest career as a chemical engineer. Dr. Perry began
his chemical engineering career in 1937.
Acknowledgment
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Purpose of Report
Micronutrients Important
to Higher Plant Life
Martens, Westermann, 1991
Borori;
Copper;
Iron;
Manganese;
Molybdenum; and
Zinc.
Micronutrients help cultivate healthy crops and
are a necessary part of the human diet.
Deficiencies impact plant growth by hindering
photosynthesis, respiration, and other basic internal
chemical processes that allow the plant to grow. Six
micronutrients are regarded as important to higher plant
life: boron, copper, iron, manganese, molybdenum, and
zinc1. These micronutrients are typically added to fertiliz-
ers as oxides, sulfates (and their hydrates), sodium salts,'
and chelates (combined chemically with resins).
As important as they are, micronutrients are only needed
in small quantities. As a result, when micronutrients are
applied to deficient cropland, they are generally used in
trace or small amounts and applied as ,an additive to the
primary crop fertilizers of nitrogen, phosphorous, and
potassium2.
Some industrial wastes contain elements which can be used, or converted for use, in-micro'nutrient
fertilizers. The United States encourages the recycling of industrial waste in a safe manner for use in
micronutrient fertilizers. However, some wastes may contain hazardous constituents that provide no
nutritive value to the plant. The use of these wastes in micronutrient fertilizers introduces these con-
stituents into the greater ecosystem. These constituents could be hazardous to handle by applicators,
contribute to contaminated runoff from land application sites, or be taken up in plants.
This report is intended for use by the public, industry, users of micronutrient products, regulatory
agency representatives, and federal and state auditors, all of whom share a common interest in the
development and use of micronutrient fertilizers made from industrial byproducts. The information
in this report provides a common technical framework to facilitate discussion between these groups.
Specifically, the report contains a summary of existing information about micronutrient fertilizers
manufactured from industrial byproducts, descriptions of the industrial processes involved in their
development and use, information on the contaminants that may be present, and methods to land
apply micronutrient fertilizers. The process information presented focuses primarily on zinc micronu-
trient fertilizers, since they account for the majority of fertilizers made from industrial byproducts.
An overview of the current federal and state regulations applicable to this industry, as well as existing
international regulations, is included at the end of this report. However, due to the changing nature
of regulations applicable to this industry, this report is not intended to serve as a guide to compliance
with regulatory programs.
Purpose of Report
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Organization of Report
Chapter 2 presents an overview of the micronutrient fertilizer industry;
Chapters discusses the industrial processes that result in zinc-bearing byproducts;
Chapter 4 discusses the processes used in the micronutrient industry to create the
products that are sold to fertilizer blenders;
Chapter 5 discusses methods of formulating fertilizer products;
Chapter 6 presents a discussion of land application methods used with zinc
micronutrients;
presents an overview of regulations that impact the micronutrient fertilizer
industry; and
Chapter 7
Chapters contains a list of references.
Purpose of Report
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Overview of the Micrnniitrient Fertilizer Industry
The main micronutrients used in U.S. agriculture today are zinc, iron, manganese, and copper3.
Micronutrients are typically used in small amounts and are often mixed with other fertilizers
(i.e.,. nitrogen, phosphorus, and potassium). In 1996, U.S. agriculture used 23 million tons of
nitrogen fertilizers, 7 million tons of phosphorus fertilizers, and 6 million tons of potassium fertilizers4.
Micronutrient fertilizers account for only 1% to 1.5% of the total. This chapter presents an overview
of the micronutrient fertilizer industry, including the classes of micronutrients, the industrial byprod-
ucts used, and an overview of the production process. .
2.1 Classes pf Micronutrients
Micronutrients vary in physical and chemical state, cost, and availability to the plant. There are three
classes of micronutrients:
Inorganic sources;
Synthetic chelates; and
Natural organic complexes.
At one time, fritted glass products were also considered a class of micronutrients, but they are not in
use to the extent they once were. .
Inorganic sources include oxides, carbonates, and metallic salts and are usually the least costly sources
of micronutrients. Oxides, such as manganese oxide and zinc oxide, are in common use, but are insol-
uble in water and therefore less effective in crop use. Sulfates are water-soluble and dissolve quickly
after application, making them especially useful. Common sulfates include copper sulfate, iron sul-
fate, manganese sulfate, and zinc sulfate. Oxysulfates are oxides that have been partially acidulated, or
made acidic, with sulfuric acid. The water solubility of these Oxysulfates is related to the degree of'
acidulation2.
Synthetic chelates are manufactured by combining a chelating agent with a metal cation. The most
common chelating agent is EDTA (ethylenediaminetetraacetic acid). Other chelating agents, such
HEDTA (N-hydroxyethyl-ethylenediaminetriacetic acid) and EDDHA (ethylenediamine
as
di (o-hydroxyphenylacetic acid)), are more expensive and used primarily with high-value crops.
Chelated micronutrients are most often in liquid form and mixed with liquid fertilizers, although
dry chelates are sometimes mixed with solid fertilizers2.
Natural organic complexes are created by reacting metallic salts with organic byproducts. Most often,
digest liquors from the wood pulp industry (both sulfite and kraft pulp processes) may be reacted to
form a metal sulfate or metal oxide. Zinc, iron, copper, and manganese have all been used in natural
organic complexes2. ,
2.2 Industrial Byproducts Used in MicrunutriEnts
Most micronutrients produced in die United States for use in agriculture originate from industrial
metal-bearing byproducts. Zinc micronutrients are of particular interest because they are the most
common fertilizer additive made from recycled hazardous waste5. The use of industrial byproduct
material as a micronutrient source raises the question of potential contamination. Untreated byprod-
ucts may contain lead, cadmium, or other heavy metals and dioxins. Because of their availability as
Overview of the Micronutrient Fertilizer Industry
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industrial Byproducts, zinc and iron are the two micronutrients most likely to be incorporated in fer-
tilizers from materials designated as a hazardous waste under the Resource Conservation and Recovery
Act(RCRA)6. . ,
Table 2-1 lists examples of industrial byproduct sources for the most common micronutrients in the
U.S. The table separates the byproducts by micronutrient, focusing on the micronutrients of primary
concern. Where known or suspected, potential contaminants for each source are listed. Gaps in the
table are areas where data are lacking or have not yet been identified
Table 2-1 Industrial Byproduct Sources for theTop Micronutrients in Use in the U.S.
Micro- Byproduct or Byproduct Source Micronutrient Product(s) ! Potential !
niitrient : Contaminant(s) |
Zinc
Iron
Manganese
Copper
Electric arc furnace dust (K061)
Brass foundry dust
Brass mill slag
Tire ash
Galvanizing waste
Mill scale
Pickle liquor
Mining waste (tailings)
Demetallized photographic fluid
Hydroquinone production byproduct
Manganese carbonate baghouse dust
Copper industry wastes
Zinc sulfate, zinc oxide,
ammoniated zinc sulfate,
zinc chloride, zinc oxide
Zinc sulfate, zinc oxysulfate,
ammoniated zinc sulfate,
zinc chloride, zinc oxide
Zinc sulfate, zinc oxysulfate,
ammoniated zinc sulfate,
zinc chloride, zinc oxide
Zinc sulfate, zinc oxysulfate,
ammoniated zinc sulfate,
zinc chloride, zinc oxide
Zinc sulfate, iron sulfate,
ammoniated zinc sulfate,
zinc chloride, zinc oxide
Ferrous sulfate monohydrate
Blended multi-nutrient
Manganese sulfate (animal feed)
Manganese sulfate (animal feed)
Copper sulfates, copper oxides
Lead, cadmium, dioxins
Lead, cadmium
Heavy metals
Cadmium
Heavy metals
Heavy metals
Heavy metals
Heavy metals
Heavy metals
Heavy metals
Heavy metals
Heavy metals
Overview of the Micronutrient Fertilizer Industry
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Z.3 General MicrnnutriEtit Fertilizer Prnductinn Overview
Figure 2-1 presents a simple overview of the major steps in micronutrient production using industri-
al byproducts. Industrial processes that generate zinc-bearing byproducts are discussed in Chapter 3.
Industrial byproducts are sent to a micronutrient manufacturer for processing. The form and quality
of the byproduct and the specific micronutrient being produced determines the process used to create
the micronutrient. For example, some industrial byproducts must be filtered before being processed
into a micronutrient fertilizer.7 The processing and recovery of zinc micronutrients are discussed in
more detail in Chapter 4. Micronutrients are then packaged as a liquid or solid and sold to a fertiliz-
er production facility or an end user where they are typically blended with primary nutrients (N, P, or
K) into fertilizer. Fertilizer formulation is discussed in Chapter 5. .._... '_.
There are various methods by which fertilizers, including micronutrients, can be applied to-cropland.
The selection of the method depends on a variety of factors such as crop type, soil type, timing of
application (i.e., at which stage "of the crop growth cycle), and fertilizer type. Fertilizer can be applied
in three basic forms: pellets (the most common); powder; and liquid. The m'ain methods of applica-
tion are broadcast spreading, band application, injection, and fertigation (i.e., application of fertilizer
through an irrigation system). Methods of land application are discussed in more detail in Chapter 6.
Figure 2-1. Overview of Micronutrient Production
N,P,K Fertilizer
Brass Mill Slag
Galvanizing
Skimmings
RE3E5
*;..- v ..^. ^-'
Spent Acids Tire Ash Brass EAFDusI
Fume Dust (K061)
Land Application
Sources
:,_;,
Overview of the Micronutrient Fertilizer Industry
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Overview of the Micronutrient Fertilizer Industry
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Industrial Sources d Zinc-Bearing Byproducts
A Imost any zinc-bearing industrial byproduct could be used to manufacture micronutrients.
/\ However, .the Resource Conservation and Recovery Act (RCRA) places certain restrictions on
JL JLdie use of hazardous waste-derived fertilizers (discussed in Chapter 7). In 1999, the tons of zinc
micronutrient fertilizers produced from nonhazardous materials was roughly equivalent to the tons of
zinc micronutrient fertilizers produced from hazardous waste8. Table 3-1 lists the most common
industrial byproducts used in the production of zinc micronutrients, including the estimated amount
generated and used in fertilizer production in 1997 (or the most current year data was available), the
typical RCRA status of that material (i.e., whether hazardous or nonhazardous), and the zinc content.
Table 3-1 Industrial Byproducts Most Commonly Used in Zinc Micronutrient Fertilizers
Annual Arinual Amount Used in Typical Zinc Content
Wlatenai Generation (tons) Pert lizer Production (tons) RCRA Status (%)
! i .
EAF dust
(K061)
Brass fume dust
(D006, D008)
Tire ash
(D006, D008)
Zinc fines
from galvanizing
925,000
32,200
7,500
Unknown
10,000
842
3,120
10,836
Hazardous
(Pb, Cr, Cd)
Hazardous
. (Pb, Cd)
Hazardous
(Pb, Cd)
Nonhazardous
15-25
40-60
27-35
60-75
Currently, the following industrial processes are identified
as sources of zinc for the micronutrient industry: steel
manufacturing, galvanizing, brass manufacturing
(foundries and mills), and tire incineration. This list may
change over time due to changes in industrial processes
and the changing regulatory environment for zinc
micronutrients. This chapter provides a brief description
of each manufacturing process that creates zinc byproduct
materials for use in the micronutrient industry. Process
flow diagrams are included at the end of the section.
Industries Generating
Zinc-Bearing Byproducts
Steel Manufacturing;
Galvanizing;
Brass Foundries;
Brass Mills; and
Tire Incineration.
Industrial Sources of Zinc-Bearing Byproducts
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3.1 Steel Manufacturing: Electric Arc Furnace Dust (KDBt)
The electric arc furnace (EAF) is uniquely suited for the production of high quality steels. The furnace
is a cylindrical vessel with a dish-shaped refractory hearth and three electrodes that lower from the
dome-shaped, removable roof. Tar-bonded magnesite bricks form the lining of the furnace. The walls
typically contain water-cooled panels that are covered to minimize heat loss. The electrodes may also
be equipped with water- cooling systems.
The cycle in EAF steelmaking consists of scrap charging, melting, refining, de-slagging, and tapping.
In addition to scrap steel, the charge may include pig iron and alloying materials. As the steel scrap is
melted, additional buckets of scrap may be added to the furnace. The EAF generates heat by passing
an electric current between electrodes through the charge in the furnace. Lime-rich slag removes the
steel impurities (e.g., silicon, sulfur, and phosphorus) from the molten steel. Oxygen may be added to
the furnace to speed up the steelmaking process. At the end of a heat, the furnace tips forward and the
molten steel is poured off. Most EAFs are operated with dry air cleaning systems which capture
released particulates as dust, although a small number of wet and semi-wet systems also exist which
capture particulates as sludge. Figure 3-1 presents a simple schematic of the EAF steelmaking process.
Figure 3-1. Electric Arc Furnace Steel Manufacturing
Air Outlet
Baghouse
Scrap
Furnace
EAF Oust (K061)
Operation of an EAF generates K061, a listed RCRA hazardous waste defined as "emission control
dust/sludge from the primary production of steel in electric furnaces." Approximately 90% of partic-
ulate emissions from an EAF are generated during the melting and refining steps and the remaining
10% are generated during charging and tapping9. Generally a mill generates between 20 and 40
pounds of EAF dust per ton of steel produced9.
Industrial Sources of Zinc-Bearing Byproducts
-------
K061 generation includes entrainment of particles of calcium oxide (CaO), rust, and dirt that are in
the scrap metal and pulled out of the EAF in the off-gas system. In addition, certain metals volatilize
as the scrap metal heats up (iron, zinc, lead, cadmium, and ckrorhium). These metals .tend to form
oxides following volatilization and are present as such in the EAP dust. EAF dust can vary greatly in
composition depending on the composition of the scrap and additives used. When lower grades of
steel are used (mainly in carbon steel production), the dust generated can contain, concentrations as
high as 44% for zinc oxide and 4% for lead' oxide9. Dust from stainless steel production can contain
high levels of chromium and nickel oxides (12% and 3%, respectively), as well as lower levels of cad-
mium (around 0.1%)9. Table 3-2 presents concentrations of metals in EAF dust for stainless and car-
bon steel production.
Table 3-2 Comparative Chemical Composition of Dust from EAFs
I * '
. . . Stainless Steel Dust Carbon Steel Dust
unemicai (% bi wejght) (% by wejght)
Iron
Zinc
Cadmium
Lead
Chromium
Calcium Oxide
31.7
1.0
0,16
1.1
10.2
3.1
28.5
19.0
<0.1
2.1
0.39
10.7 (a)
(a) Calcium oxide and magnesium oxide combined.
Source: AISI, 2000.
Over the past few years, dioxin and furan generation in the incineration processes used in steel man-
ufacturing has become an area of study since the components of the off-gas stream in an EAF may
result in the formation of dioxins. The Foundation of Metallurgical Research showed that the biggest
contributors to dioxins in scrap steel melting were polyvinyl chloride (PVC) coated scrap and oily
scrap10. It was also found that the baghouse outlet emission concentrations of dioxins ranged from
20% to 60% of the inlet stream concentration. These data indicate that dioxins are captured in the
baghouse and this conclusion is supported by research that indicates that 20% to 30% of dioxins are
bound to particulates".
There are 17 forms of dioxins considered to be toxic. The most toxic dioxin is 2,3,7,8-tetra-
chlorodibenzo-p-dioxin (TCDD). Other similar dioxins have been assigned toxicity equivalency fac-
tors (TEFs) relative to 2,3,7,8-TCDD, which is assigned a TEF of 1. The total dioxin equivalency
(TEQ) is determined by summing the toxicity weighted values of all dioxins. Raw EAF dust (K061)
was found to have a TEQ concentration of 815 ng/kg and granular zinc fertilizer from K06l was
found to have concentrations of 342 and 322 ng/kg4. The TEQ values for K061 and granular zinc fer-
tilizer do not exceed the RCRA nonwastewater standard for all TCDDs of 1,000 ng/kg12.
In recent years, most micronutrient companies have stopped using K061 and moved to other sources
of zinc. One U.S. company still uses K061 to create zinc oxysulfate in a process located on site at a
steel manufacturing plant. Since the facility is located at the byproduct source, there is no transporta-
tion or storage of the K06113.
Industrial Sources of Zinc-Bearing Byproducts
f "." -".- ". -
f ;*,M;- --
?~'^: 4
-------
Currently, the primary user of K061 in the United States is Horsehead Industries. Horsehead uses high
temperature separation techniques to obtain zinc and lead products for sale back to the metals indus-
try". Zinc Nationale in Monterrey, Mexico receives some zinc oxide from Horsehead14. Zinc Nationale
produces zinc oxide and zinc sulfate compounds from K061 for use as animal feed and fertilizer. It is
suspected that some of these micronutrients are sold in the United States7.
3.2 Brass Smelters and Foundries: Brass Fume Dust (DDDB, DDDB)
Both foundries and smelters melt metals and form them for use. Smelters take metal-bearing materi-
als and process them into ingots. Foundries process ingots into shapes that can be used commercially.
Smelters and foundries exist for every industrial metal. Brass is an alloy composed of copper and zinc.
Red brass contains 6 percent of zinc while yellow brass contains up to 41 percent15. Brass smelters and
foundries are of interest because the zinc content of their byproducts is sufficient for use in micronu-
trients.
Smelters'. Brass smelting involves collecting and melting raw materials for forming into
ingots. A general diagram of the process is depicted in Figure 3-2. Copper- and zinc-
bearing raw or recycled materials, such as copper wire and radiators, are collected and
melted. Chemicals and other elements are added to the molten metal to create a desired
mixture. The mixture is poured into forms and allowed to cool. After removal from the
forms, the product is cleaned and excess metal is removed to be recycled. Metal shav-
ings can either be recycled back into the process or sold to a byproduct industry. The
final product is a metal ingot with specific, known properties16.
Figure 3-2. Brass Foundry Processing
D006/D008
Furnace
Mold
Cooling
Brass Ingots
industrial Sources of Zinc-Bearing Byproducts
-------
Foundries. Brass foundry processes typically involve melting brass ingots and brass
scrap in an induction furnace, which consists of hollow vertical cylinder lined with
heat-resistant refractory material arid ringed with electric coils17. Heat induced by the
electric coils melts metal inside the furnace. The molten metal is then cast in molds,
which are most frequently made of a moist sand media ("green sand"), although other
molding methods, including investment casting and permanent molding are also used
for brass. Molds are prepared by compressing sand in a box or "flask" around a wood
or plastic pattern (shaped like the exterior of the desired product); once the sand is
mechanically compacted in shape, die pattern is removed. The top and bottom halves,
or "cope" and "drag"of the mold, are formed separately and a core (shaped like the
interior space of the product) is set into the mold when the two halves are joined,
forming a cavity. Molten brass is transferred (tapped) from the furnace and poured into
the mold cavity through a prepared channel in the mold, "called a sprue18-19. The molds
are then transferred from the dedicated pouring area and cooled, allowing the metal to
solidify. When cool, the castings are separated from the mold and core sand by shak-
ing, knocking or tumbling in a process known as "shake out"18. Sprues and other excess
metal and sand are removed from die casting with hammers and saws and are returned
to the furnace as scrap. Finally, the product surface is cleaned and finished using grind-
ingi shot blasting, and machining methods. A general diagram of the process is depict-
ed in Figure 3-3. ' .
Figure 3-3. Brass Foundry Processing
1
Finishing * Inspecting
Cleaning
Both brass smelters and brass foundries have similar byproduct sources that could be used by the
micronutrient industry. During the melting and pouring process, particles coming off the molten
metal are collected using air cleaning systems, similar to the systems used with electric arc furnaces to
capture released particulates as dust or sludge16. Brass fume dust is usually characteristically hazardous
for both lead and cadmium and is designated as D006 and D008. Lead levels in brass fume dust can
be as high as six percent20. Currently, brass fume dust is primarily used in animal feed production or
for zinc reclamation8. Shavings or chips from cleaning or-post-process forming are also valuable sources
of zinc.
Industrial Sources of Zinc-Bearing Byproducts
-------
3.3 Tire Incineration for Energy Recovery: Tire Ash (DQDB, DD08)
Tire-to-energy facilities use the heat generated from the incineration of tires as a source of energy.
About 5% of the weight of the tires incinerated remains as ash. The ash is collected from particulate
matter captured in a baghouse similar to brass and steel fume collection. The baghouse dust, which
contains zinc, has been used as a micronutrient source in the past8.
Tire ash is characteristically hazardous for both lead and cadmium and designated as D006 and
D0088. Tire ash, as a raw material, has a total dioxin equivalency unit concentration (toxicity weight-
ed average of dioxin congeners) of 1.62 ng/kg; granular zinc fertilizer made with tire ash has a con-
centration of 5.60 ng/kg4. Dioxins are discussed in more detail in Section 3.1. The dioxin levels in tire
ash are well below the RCRA nonwastewater standard for all TGDDs of 1,000 ng/kg12. It is not
believed that micronutrient manufacturers use tire ash as an input to their process at this time7.
3.4 Galvanizing Operations: Zinc Dross and Skimmings and Spent Acids
Galvanizing is the process of applying a zinc coating to iron or steel for protection from corrosion. The
zinc coating is applied using a hot-dip galvanizing or electrogalvanizing process. Spent acids as well as
zinc-bearing skimmings from either galvanizing process can be processed and used as raw materials in
the micronutrient industry2. Zinc skimmings are considered a non-hazardous waste and are not sub-
ject to RCRA controls20. Lead levels in non-hazardous galvanizing waste are typically between one and
two percent21.
Hot-dip galvanizing is a five-step process that includes cleaning, annealing, coating with zinc, chemi-
cal treating, and working. Four different processes can be used in the cleaning step, all resulting in the
removal of surface oils and impurities:
1. Flame oxidation of the steel;
2. Electrolytic cleaning, scrubbing, hot-water rinsing, and hot-air drying of the steel;
3. Acid pickling, alkaline cleaning, and fluxing of the steel; and
4. Cleaning and annealing in one step using a reducing-flame furnace.
Annealing is the process by which the steel (or iron) is heated to prepare the surface for reaction with
molten zinc. Annealing usually takes place during the cleaning process but can be conducted after-
wards. After cleaning and annealing, the metal is dipped in molten zinc for one to ten seconds. The
galvanized metal is cooled before being treated with chromium compounds to resist staining. Finally,
the product is cold worked to ensure a more consistent surface21. Figure 3-4 presents a simple diagram
for the hot-dip galvanizing process.
Figure 3-4. Hot-Dip Zinc Galvanizing Process
Cleaning
Rinsing
Annealing
Rinsing
Zinc
bath
(Coating)
Chemical
Treating
Cooling and
inspection
Industrial Sources of Zinc-Bearing Byproducts
-------
The zinc micronutrient industry is primarily interested in waste products from the coating step.
During the galvanizing process an oxide film can develop on the surface of the molten zinc; this film
must be removed to prevent interference with the reaction of the zinc with the metal to be galvanized.
It is common for the zinc bath to contain a small amount of lead, iron, and aluminum. Excess iron
can settle to the bottom of the bath as dross (FeZn13) or it may react with excess aluminum to form
an iron-zinc-aluminum alloy which floats to the surface as skimmings before being removed21.
Zinc-bearing materials recovered from the bath that can not be recycled into the process are sold to
zinc recycling facilities who process the materials for sale back to galvanizers, to brass foundries, or to
the micronutrient industry.
Electrogalvanizing involves preparation steps similar to hot-dip galvanizing. The methods differ in the
application of the zinc to the galvanized metal. Electrogalvanizing does not require the use of furnaces,
molten zinc, or a cooling tower. The electrogalvanizing process uses an electrical current which passes
through the zinc solution from an anode to the galvanized metal. The process allows the zinc to bond
to the iron or steel. Zinc can be applied from anodes that are constructed of a soluble zinc material or
the zinc can be applied from a process solution21. Any spent solution that contains zinc still in solu-
tion is a viable byproduct for the micronutrient industry.
Before use, the galvanizing byproduct material is processed by the zinc reclaiming industry to create
two products: zinc fines and zinc metal ingots. Zinc fines are sold to the micronutrient industry while
zinc metal ingots are sold back to the galvanizing industry or to brass foundries7.
Industrial Sources of Zinc-Bearing Byproducts
-------
Industrial Sources of Zinc-Bearing Byproducts
-------
of Zinc MicrnnutriEnts
Types of Zinc Micronutrients
Zincsulfate;
Zincoxysulfate;
Ammoniated zinc sulfate;
Zinc chloride; and
Zinc oxide.
The compounds most commonly used to deliver
zinc to the soil are zinc sulfate and zinc oxysulfate.
Zinc sulfate is normally used in the form zinc sul-
fate monohydrate. The physical properties of sulfates
make them well suited for fertilizer use because they are
water soluble and dissolve easily into the soil2. Additional
compounds that can be used to deliver zinc are ammoni-
ated zinc sulfate, zinc chloride, and zinc oxide.
Ammoniated zinc sulfate is used when blending with
liquid phosphorus fertilizers. Zinc chloride and zinc
oxide are not used as frequently but maintain a small
portion of the market7. The processes used to develop
each compound are similar, and are described below.
EPA has estimated that there were approximately 16 facilities producing zinc micronutrient fertilizers
in 1998. Only two of the zinc micronutrient fertilizer producers were known to use hazardous feed-
stocks; the remainder use nonhazardous sources. Two additional facilities are believed to use hazardous
byproducts to produce zinc micronutrients for use in animal feedstocks8.
4.1 Zinc Sulfate
Figure 4-1 presents a simple process flow diagram for zinc sulfate manufacturing. Zinc sulfate is cre-
ated by digesting a zinc source in sulfuric acid and water. The amount of sulfuric acid used in the
process is determined stoichiometrically to react with all of the zinc contained in the byproduct. Since
zinc sulfate is water soluble, the liquid may be filtered to remove wastes and impurities (lead and cad-
mium are of greatest concern). Filtered metals are sent to a smelter for reprocessing or stabilized and
sent to a landfill. The resulting zinc sulfate slurry is either packaged for sale as a liquid fertilizer or sent
to a drier where it is crystallized. Some of the dry zinc sulfate is sold in the crystallized form, but most
is granulated and sized for sale. Oversized materials are sent through a hammer mill and reintroduced
to the granulator with any undersized materials7. The filtration process results in a consistent product,
regardless of the specific raw materials used8. Table 4-1 presents some limited results of contaminants
present in samples of zinc sulfate micronutrient products made from industrial byproducts.
Table 4-1 Sample Results for Zinc Sulfate Monohydrate Micronutrient Products
Fertilizer Range of Zinc in CadrUum Lead Comments
Type Fertilizer (%) (mg/kg); (mg/kg)
Zinc Sulfate
[Zinc Sulfate
Monohydrate
35.5 - 36
31.4-37.7
<2.7 - 28
4 - 28.8
25-69
3 - 84.2
Based on average values
for four different products.
Based on composite samples of five
different products over four years.
^T
111 \ |1
m\
,.:*WI
Source: Big River Zinc, Tetra Micronutrients.
Processing/Recovery of Zinc Micronutrients
-------
Figure 4-1. Zinc Sulfate Manufacturing
Tractor
4.2 Zinc DxysulfatE
Zinc oxysulfate is created by combining a zinc-bearing byproduct with sulfuric acid. This process
involves putting byproduct dust in a rotating drum or tube type granulator and spraying it with a sul-
furic acid and water mix. As discussed in Chapter 2, the byproduct may have to be ground into a
usable form before entering the process. The raw material, water, and sulfuric acid mixture is granu-
lated and dried to remove excess water. Granulated zinc oxysulfate is sent through a series of sizing
screens to divide the mixture into marketable sizes. Sometimes this process is reversed and the granu-
lated zinc oxysulfate is sized before being dried. Oversized materials are sent through a hammer mill
and reintroduced to the granulator with any undersized materials. After packaging, the sized zinc oxy-
sulfate is sold to fertilizer manufacturers. For effective crop use, typically 35% to 50% of the zinc is in
water-soluble form2. Figure 4-2 presents a simple process flow diagram for zinc oxysulfate manufac-
turing.
Traditionally, zinc fertilizer manufactured from K061 has been produced in oxysulfate form. Since
there is no filtration step in the manufacture of zinc oxysulfate, any deleterious materials in the raw
materials that are not filtered out during byproduct processing are in the final product23. There has
recently been a movement away from the manufacturing of zinc oxysulfate using industrial byprod-
ucts20. Table 4-2 presents some limited results of contaminants present in samples of zinc oxysulfate
micronutrient products made from industrial byproducts.
Processing/Recovery of Zinc Mieronutrients
-------
Figure4-2. Zinc Oxysulfate Manufacturing
Farmers
Table 4-2 Sample Results for Zinc Sulfate Monohydrate Micronutrient Products
Source Range of Zinc in Cadmiurr) Lead Comments
Fertilizer (%) (mg/kg)| (mg/kg)
i
Characteristic
Hazardous Waste
(non-K061)
K061
Non Hazardous
Raw Materials
17.7-20
'18-19
20-36
ND-39
<270 - 297
<20-<150
800-1,300
14,280-15,000
<50-<1,000
Based on the average of product
monthly composite analyses for 1997
and other sample data.
Based on the average of product
monthly composite analyses for 1997
and other sample data.
Based on information provided on
typical analysis results for three
products.
Source: Tetra Micronutrients, Bay Zinc.
4.3 Ammnniated Zinc Sulfate
Chemical properties prevent zinc sulfate from being soluble in phosphate-based liquid fertilizer.
Mixing ammonia with zinc sulfate creates a product, ammoniated zinc sulfate, which is soluble in
phosphate-based liquid fertilizer7. Ammoniated zinc sulfate is created by adding ammonia after the
creation of liquid zinc sulfate. Manufacturing'companies either create the zinc sulfate themselves or
buy it before it goes to the fertilizer blender7. The final product is sold to a fertilizer blender.
4.4 Zinc Chloride
Zinc chloride is created using the same process as zinc sulfate except hydrochloric acid is used in place
of sulfuric acid. However, the lead contaminants that may be present from industrial byproduct
sources are dissolved by hydrochloric acid during this process. Because the lead is now dissolved, it is
no longer possible to remove this contaminant through filtration. Therefore, if starting with the same
source of zinc byproduct, zinc chloride has higher concentrations of lead than zinc sulfate. In addi-
tion, while sulfides are considered beneficial to crops, chlorides may sometimes harm them7.
Processing/Recovery of Zinc Micronutrients
-------
4.5 Zinc Oxide
Zinc oxide is not typically made from industrial sources. One method of producing zinc oxide is by
roasting sphalerite (ZnS), a naturally occurring zinc compound. The zinc oxide is sold as a fine pow-
der or in granular form. Since it is insoluble, it is not immediately available to crops when applied in
a granular form2. Zinc oxide is not extensively used as a fertilizer7.
Processing/Recovery of Zinc Micronutrients
-------
Product Formulation
1 "V ecommended application rates for mioronutrients are typically much lower than for N-P-K fer-
1^^ tilizers. Because of this, micronutrients may be combined with N-P-K fertilizers to reduce costs
JL ^and improve application. Micronutrients are incorporated, bulk blended, or coated onto gran-
ular fertilizers, or mixed with liquid fertilizers, to create final formulated fertilizer products.
5.1 Liquid Formulating
Liquid formulations typically contain mixtures of one or more raw materials, inert ingredients, and a
base solvent (such as water), and may also contain emulsifiers or surfactants. Solid materials, such as
powders or granules, may also be used as part of a liquid formulation by dissolving or emulsifying the
dry materials to form a liquid or suspension. The formulated product may be in a concentrated form
requiring dilution before application, or may be ready to apply.
Micronutrients may be applied in a liquid form alone or mixed with fluid N-P-K fertilizers. For exam-
ple, zinc micronutrients are often mixed in starter fertilizers. However, the solubility of the micronu-
trient impacts the degree to which it may be mixed in a fluid fertilizer. Where solubility limits the
amount of micronutrient that can be added to a fluid fertilizer, a suspension fertilizer may also be
used. Typically, powdered sources of micronutrients are incorporated to the fluid fertilizer just prior
to application in the field. Because complete solution of the micronutrient is not required, higher con-
centrations of micronutrients (such as zinc oxide) can be incorporated.
An example of a liquid-based formulating line
is shown in Figure 5-1. Typical liquid formu-
lating lines consist of storage tanks or con-
tainers to hold active and inert raw materials,
and a mixing tank for formulating the final
product. A storage tank may also be used on
the formulating line to hold the formulated
product, prior to a packaging step. Facilities
may receive their raw materials in bulk and
store them in bulk storage tanks, or they may
receive the raw materials in smaller quantities,
such as 55-gallon drums, 50-pound bags, or
250-gallon minibulk containers or "totes."
These raw materials are either piped to the
formulation vessel from bulk storage tanks, or
added directly to the vessel from drums, bags,
or minibulks (smaller, refillable containers).
Typically, water or the base solvent is added to
the formulation vessel in bulk quantities.
Figure 5-1. Typical Liquid-Based Formulating Line
Drums
Formulated
Product
Storage
Formulation
Vessel
Minibulk
The formulating line may also include piping and pumps for moving the raw material from the stor-
age tanks to the mixing tank, and for moving formulated product to the packaging line. Other items
that may be part of the line are pre-mixing tanks, stirrers, heaters, bottle washers, and air pollution
control equipment. Some lines may also contain refrigeration units for formulation and storage units,
scales, and other equipment.
v 4
Product Formulation
-------
5.2 Dry Formulating
Dry formulations may be in different forms, such as powders, dusts, or granules. They are formulated
in various ways, including mixing powdered or granular actives with dry carriers, spraying or mixing
a liquid ingredient onto a dry carrier, soaking or using pressure and heat to force ingredients into a
solid matrix, and drying or hardening an ingredient solution into a solid form. These dry products may
be designed for application in solid form or to be dissolved or emulsified in water or solvent prior to
application.
Micronutrients may be applied in a granular form alone or blended with N-P-K fertilizers. More often,
a fertilizer dealer purchases fertilizer products in bulk and blends them together in specific proportions
according to the needs of the end user or farmer. Blending typically occurs just prior to field applica-
tion to minimize the chance for chemical reactions to occur.
Dry formulating lines typically have tanks or containers to hold the active ingredients and inert raw
materials, and may include mixing tanks, ribbon blenders, extruding equipment, vacuum or other type
of drying equipment, tanks or bins for storage of the formulated product, pelletizers, presses, milling
equipment, sieves, and sifters. Figures 5-2 and 5-3 are examples of granular and dry spray-coated pro-
duction lines.
The coating procedure for micronutrient fertilizers is usually simple, using rotary drum or ribbon mix-
ers. Typically, a finely ground micronutrient is combined with a granular fertilizer. A liquid binding
agent is then sprayed onto the granules during mixing. Binding agents include water, waxes, oils, or a
fertilizer solution. Anti-caking agents may also be used. Due to the increased costs associated with this
formulation, coating is used primarily to add micronutrients to specialty fertilizers.
Figure 5-2. Typical Granular Formulating Line Figure 5-3. Typical Dry Spray-Coated Formulating Line
Bags
Ribbon
Mixer
Formulated
Product
Storage
Heated
Air
Spray Dryer
Air
Liquid
Ingredient
Hold Tank
Solids
Cyclone
Dust
Final
Product Bin
Product Formulation
-------
Raw materials for dry fertilizer products may be liquid or solid. Liquid raw materials may be stored in
rail tank cars, tank trucks, minibulks, drums, or bottles. Dry raw materials may be stored in silos, rail
cars, tank trucks, minibulks, supersacks, metal drurns, fiber dflimsj bags, or boxes. Liquid raw mate-
rials may be pumped, poured, or sprayed into formulation vessels, while dry raw materials are fre-
quently transferred to formulation equipment by screw conveyors (consisting of a helix mounted on a
shaft and turning in a trough), through elevators, or by pouring.
Dry formulating lines may also include piping and pumps for moving raw materials from storage tanks
to the formulation equipment, and for moving formulated product to the packaging equipment.
Other items that may be included in the dry product line are pre-mixing tanks, tanks for storing for-
mulated product prior to packaging, stirrers, heaters, refrigeration units on formulation and storage
equipment, scales, and air pollution control equipment (e.g., cyclones, filters, or baghouses). Dry
products may be packaged into rail tank cars, tank trucks, totes, and minibulks, but are typically pack-
aged into bags, boxes, or drums.
- .f
\
Product Formulation
-------
Product Formulation
-------
Land Application nf Zinc Micrnnutrients
s
oil applications are the most commonly used and effective methods for correcting zinc deficiencies2.
This chapter briefly discusses the application of zinc micronutrient fertilizers to cropland. The
sources and classes of zinc micronutrient fertilizers were discussed in Chapter 2.
B.I Application Methods
Micronutrients may be applied alone or may be mixed in with a nitrogen, phosphorus, or potassium
(NPK) fertilizer. Micronutrients are typically applied in combination with a NPK fertilizer, which
results in a more uniform fertilizer distribution. It also helps to reduce application costs since all the
required fertilizer is applied at once. One drawback is possible reactions between the various chemi-
cals in the fertilizer2. ,
There is no conclusive data on which type of zinc fertilizer is most effective. Most fertilizer distribu-
tors perceive no difference between the two major types of zinc micronutrient fertilizers: zinc oxysul-
fate and zinc sulfate monohydrate. Zinc sulfate monohydrate may be more readily available to plants
since it is more soluble. However, it is possible that chemical reactions in the soil can convert zinc oxy-
sulfate into a more usable form. Zinc is applied to cropland based on the concentration needed. The
average zinc application rate is 5 pounds per acre.8
Fertilizers can be applied in many forms, such as pellets (the most common), powders, or liquids. The
selection of the application method depends on a variety of factors including fertilizer class, crop type,
soil type, and timing of application (i.e., at which stage of the crop growth cycle the fertilizer is to be
applied). The basic application methods include surface application (e.g., broadcast or band applica-
tion), subsurface application (or injection), irrigation, and foliar application which are described in
greater detail below.
Broadcast Spreading. Broadcast spreading is a
method by which the fertilizer is evenly spread
across the soil surface. It is most often used to
apply dry fertilizers and is performed prior to
planting. Incorporation of the fertilizer through
plowing or harrowing can help prevent runoff and
help make the nutrients more available for uptake
at the root zone. The preferred form of fertilizer for
broadcast spreading is pellets since they are easier
to handle than powder. Powder can stick together,
preventing free flow in the hopper of the spreading
equipment25. Figure 6-1 depicts a broadcast
spreader.
Figure 6-1. Broadcast Spreading
Fertilizer
Hopper
Broadcast Spreader
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Ss-i-t
'«
:f. I
' g: . -^---r^^
j§ij
* '
-~fr:
Land Application of Zinc Micronutrients
-------
Band Application. Band application (banding) is a
method of applying fertilizer to the soil surface in
narrow bands along the side of a row of plants. A
fertilizer that can be broadcast spread can also be
band applied. Banding is generally performed dur-
ing cultivation but may occur during the growing
season (side dressing). Lower application rates,
compared with broadcast application, may be used
due to the lower amount of soil-zinc contact2.
Figure 6-2 depicts band application.
Injection. Injection is used to apply dry or liquid
fertilizers below the soil surface and close to the
root zone. Blades or furrow openers are used to cre-
ate channels into which the fertilizer is dropped.
Injection of fertilizers helps prevent loss of nutri-
ents due to wind and rain erosion. Injectors, how-
ever, require more power than other methods of
application and they do not perform well in stony
soil. Fertilizer injection is often performed at the
time of seeding to get the crop off to a fast-start25.
Figure 6-3 shows an example of injection of liquid
fertilizer.
Fertigation. Fertigation is the liquid application of
a water-soluble fertilizer with irrigation water. The
concentrated fertilizer is metered into the irrigation
supply line. Fertigation can be used with both
trickle and overhead irrigation systems. Fertigation
can save time, fuel, and equipment compared with
other application methods, and it reduces the
amount of compaction from equipment traveling
over the soil25. Fertilizers are best applied using fer-
tigation for crops that use drip irrigation systems.
Figure 6-4 shows an example of a fertigation sys-
tem.
Foliar Application. Foliar application is the appli-
cation of a fertilizer directly to the crop foliage and
is generally used as an emergency measure to cor-
rect a zinc deficiency that occurs during the grow-
ing season. Foliar application is accomplished by
spraying the fertilizer onto the leaves of the plant.
Foliar application is usually less effective than
broadcast and band application for correcting zinc
deficiencies and care must be taken not to damage
the leaves of the plant2.
Figure' 6-2. Band Application
Fertilizer
hopper
Drop tube
Fertilizer
applicator
Figure 6-3. Injection
Figure 6-4. Fertigation
Fertilizer
injector
Liquid fertilizer
stock tank
Land Application of Zinc Micronutrients
-------
6.2 Application Concentrations and Exposure
O.L Application uonceniraiiDns anu exposure
Table 6-1 presents common sources of zinc micronutrients use,d in land applicai
with the approximate concentration of zinc in each source. Table 6-2'presents gen^c^ ^^^
band and broadcast application procedures for correcting zinc deficiencies in various crops.
U CXpUSUrE
inc micronutrients use,d in land application activities, along
inc in each source. Table 6-2'presents general information on
Table 6-1 Sources of Zinc Used for Land Application
Source Formula Concentration of Zinc (g/kg)
Inorganic Compounds
Zinc ammonia complex
Zinc carbonate
Zinc chloride
Zinc frits
Zinc nitrate
Zinc oxide
Zinc oxysulfate
Zinc sulfate monohydrate
Zinc sulfate heptahydrate
Basic zinc sulfate
Organic Compounds
Zinc chelate
Zinc chelate
Zinc chelate
Zinc lignosulfonate
Zinc polyflavonoid
Zn-NHg
ZnC03
ZnCI2
Fritted glass
Zn(l\l03)2-6H20
ZnO
ZnO + ZnS04
ZnS04-H20-
ZnS04-7H20
ZnS04-4Zn(OH)2
l\la2ZnEDTA
l\la2ZnHEDTA
IMaZnNTA
-
....
100
520-560
480-500
100-300 ,
220
500-800
400-550
360
230
550
140
90
90
50-80
50-100
Source: Mortvedt
Land Application of Zinc Micronutrients
-------
Table 6-2 Information For Applying Zinc Micronutrient Fertilizers Using Band and Broadcast Procedures
i :
Crop Zinc Source Zinc Application Application : Comment !
Rate (kg/ha) Method ' I
Red Mexican
bean, sweet corn
Rice
Corn
Corn
Corn
Corn, "snapbean,
vegetables
Corn, snapbean,
vegetables
Flax
Corn, bean,
grain, sorghum,
sweet corn
Corn, bean,
grain, sorghum,
sweet corn
Corn, sorghum
Corn, bean,
flax, potato,
sorghum,
soybean
Na2ZnEDTA
ZnS04, ZnO
ZnS04
ZnS04, ZnO
Zn chelate
ZnS04, ZnO
Zn chelate
ZnS04
ZnEDTA
ZnS04
ZriEDTA
ZnS04
ZnS04
ZnS04
Na2ZnEDTA
ZnS04
ZnS04
0.9-1.8
9.0
34.0
6.6
11.0
2.2 - 3.3
3.3
0.6-1.1
4.5 - 9.0
1.1 -2.2
2.2 - 4.5
0.6-1.1
11.0
11.0-17.0
5.6-11.0
1.1 -2.2
<1.1
11.0
5.5
5.6-11.0
1.0-5.5
Broadcast
Broadcast
Broadcast
Band
Broadcast
Broadcast
Band
Band
Broadcast
Broadcast
Band
Band
Broadcast
Broadcast
Broadcast
Band
Band
Broadcast
Broadcast
Broadcast
Band
Apply with macronutrient fertilizer and
plow in.
Surface apply before flooding.
Reapply every 4 to 5 years.
Use finely divided ZnO.
Band with starter fertilizer; use finely
divided ZnO.
Apply with l\l, P, and K fertilizer.
Band with l\l, P, and K fertilizer.
Incorporate by plowing.
DTPA extractable Zn, <0.5 mg/kg
DTPA extractable Zn,
. 0.5 to 1 .0 mg/kg
DTPA extractable Zn1 <0.5 mg/kg;
band with starter fertilizer
DTPA extractable Zn, <0.40 mg/kg
DTPA extractable Zn,
0.41 to 0.81 mg/kg
Reapply every 2 to 4 years.
Source: Mortvedt
EPA performed a risk assessment to estimate the potential risks to human health and the environment
from contaminants in NPK fertilizers, micronutrient fertilizers, and soil amendments26. Zinc micronu-
trient fertilizers were evaluated as part of the study. The study evaluated the exposure risk to farmers
and their children through the following exposure routes23:
Direct ingestion;
Ingestion of soil amended widi fertilizers;
Inhalation of particles and vapors during fertilizer application and tilling;
Land Application of Zinc Micronutrients
-------
Ingestion of plant and animal products produced on soil amended with fertilizers; and,
Ingestion of fish from streams located adjacent to fertilizer-amended fields.
The study concluded hazardous constituents in fertilizers generally do not pose a health or environ-
mental risk. The study did find there was a risk from dioxins and arsenic which may be found in some
micronutrient fertilizers. However, usually the risk could be attributed to a single fertilizer sample that
had an unusually high contaminant concentration. For zinc micronutrient fertilizers, only 1 sample in
12 showed a risk for indirect exposure to dioxin.26 For more information, including estimates of the
addition of metals to soil from zinc micronutrients, this study can be accessed through EPA's web site,
at www.epa.gov/epaoswer/hazwaste/recyde/fertiliz/risk/index.htm.
Land Application of Zinc Micronutrients
-
-
-------
Land Application of Zinc Micron'utrients
-------
Overview of Existing Regulations
This chapter provides a brief overview of existing regulations that affect the micronutrient
fertilizer industry. The chapter contains background material on certain federal and state reg-
ulations that would be applicable to facilities generating industrial byproducts containing zinc,
as well as micronutrient processing facilities. The chapter also provides a brief look at international
regulations.
7.1 Resource Conservation and Recovery Act (RCRA)
The Solid Waste Disposal Act (SWDA), as amended by the Resource Conservation and Recovery Act
(RCRA) of 1976, addresses solid and hazardous waste management activities. The Act is commonly
referred to as RCRA. The Hazardous and Solid Waste Amendments (HSWA) of 1984 strengthened
RCRA's waste management provisions and added Subtitle I, which governs underground storage
tanks (USTs),
Regulations promulgated pursuant to Subtitle C of RCRA (40 CFR Parts 260-299) establish a "cra-
dle-to-grave" system governing hazardous waste from the point of generation to disposal. RCRA haz-
ardous wastes include the specific materials listed in the regulations (discarded commercial chemical
products, designated with the code "P" or "U"; hazardous waste from specific industries/sources, des-
ignated with the code "K"; or hazardous wastes from non-specific sources, designated with the code
"F") or materials which exhibit a hazardous waste characteristic (ignitability, corrosivity, reactivity, or
toxicity and designated with the code "D"). Most RCRA requirements, are not industry specific, but
apply to any company that generates, transports, treats, stores, or disposes of hazardous waste.
Entities that generate hazardous waste are subject to waste accumulation, manifesting, and record-
keeping standards. A hazardous waste facility may accumulate hazardous waste for up to 90 days (or
180 days depending on the amount generated per month) without a permit or interim status.
Generators may also treat hazardous waste in accumulation tanks or containers (in accordance with
the requirements of 40 CFR Section 262.34) without a permit or interim status.
Facilities that treat, store, or dispose of hazardous waste are generally required to obtain a RCRA per-
mit. Subtitle C permits for treatment, storage, or disposal facilities contain general facility standards
such as contingency plans, emergency procedures, recordkeeping and reporting requirements, finan-
cial assurance mechanisms, and unit-specific standards. RCRA also contains provisions (40 CFR Part
264 Subparts I and S) for conducting corrective actions which govern the cleanup of releases of haz-
ardous waste or constituents from solid waste management units at RCRA treatment, storage, or dis-
posal facilities.
Although RCRA is a federal statute, many states implement the RCRA program. Currently, EPA has
delegated its authority to implement various provisions of RCRA; to 47 of the 50 states and two
United States territories. Delegation has not been given to Alaska, Hawaii, or Iowa.
- rr-r
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feil
Overview of Existing Regulations
-------
EPA controls the use of hazardous materials in micronutrients through the RCRA program. .RCRA
Subpart C regulates hazardous waste management from the point of generation to ultimate disposal.
Regulation of zinc micronutrient byproducts falls under Subpart C. The primary topics of Subpart C
that are applicable to zinc byproduct generators and processors are:
* Hazardous Waste Identification and Listing Identifies characteristics of hazardous wastes
and provides lists of wastes.
Generators of Hazardous Wastes Divides hazardous waste generators into categories based
on-quantities generated which determines the level of RCRA compliance required.
Transporters of Hazardous Wastes Establishes standards for recordkeeping, labeling,-and
transporting hazardous wastes.
Treatment, Storage, and Disposal Establishes standards for treatment, storage, and disposal
of hazardous wastes listed or identified in Subpart C. The land disposal restrictions (LDR)
set standards for wastes disposed directly on the land or in the ground.
The following sections discuss general RCRA regulations that are applicable to zinc byproduct gener-
ators and fertilizer processors.
Overview of Existing Regulations
-------
Waste Determinations
The definition of hazardous waste is specified in 40
CFR 261.3. This section describes what constitutes
a hazardous waste. Exclusions and exemptions
from the hazardous waste definition are outlined in
40 CFR 261.4 through 261.6. The primary haz-
ardous wastes used in the zinc micronutrient
industry are K061, D006, and D008.
The type of zinc micronutrient waste present at a
site depends on how the waste is generated and
what hazardous constituents are present. Waste
generators, such as steel mills and brass foundries,
generate sources of zinc micronutrients that fall.
under the definition of hazardous waste. These
wastes are therefore regulated by RCRA. The accu-
mulation and transport of these wastes to the
micronutrient processor must follow RCRA regu-
lations. Any storage taking place at the processor's
facility prior to introducing the waste into the
fertilizer production processmust also comply
with RCRA regulations. Once the waste is con-
verted to a fertilizer, the waste-derived fertilizer
would not be regulated under RCRA provided it
meets the applicable land disposal restriction treat-
ment standards.
Hazardous Wastes Used in Zinc
Micronutrient Industry
K061 -Emission control dust/sludge
from the primary production of steel
in electric furnaces.
D006 - Any waste having a
concentration of cadmium greater
than 1.0 mg/L. Brass fume dust and
tire ash can fall into this category.
D008 - Any waste having a
concentration of lead greater than
5.0 mg/L. Brass fume" dust and tire
ash can fall into this category.
Summary of RCRA Requirements
for the Determination of
Hazardous Waste
Waste Generator (e.g., steel mill, brass
foundry, etc.)
. Sources of hazardous zinc
micronutrient waste (e.g., electric
arc furnace dust) must be identified.
« The facility must accurately identify
' -its waste.
Micronutrient Processor (e.g., fertilizer
producer)
Sources of hazardous wastes used in
the production of micronutrients (e.g.,
K061, D006, D008) must be identified.
The facility must be permitted or
licensed to receive the hazardous
waste.
Any production processes using
the hazardous waste that generates
hazardous waste must be identified.
Overview of Existing Regulations
-------
Hazardous Waste Generator Activities
The specific RCRA requirements for generators of hazardous waste depend on the amount of waste
generated on site. Generators fall into one of three categories:
1. Conditionally Exempt Small Quantity Generators (CESQG) Generators of less than
Ikg/month of acute hazardous waste or less than 100 kg/month of other hazardous waste.
2. Small Quantity Generators (SQG) - Generators of greater than TOO but less than 1,000
kg/month of nonacute hazardous waste.
3. Large Quantity Generator (LQG) - Generators of greater than Ikg/month of acute haz-
ardous waste or greater than or equal to 1,000 kg/month of other hazardous waste.
The generator's classification determines the
level of RCRA compliance required. LQGs
are subject to the most stringent standards,
while CESQGs are exempt from most
requirements. Large and small quantity gen-
erators may only accumulate hazardous
wastes on site for a limited amount of time.
CESQGs are limited to storing 1,000 kg of
wastes at any one time. Storing amounts
greater than 1,000 kg would reclassify them
as a SQG. Waste accumulation units must
comply with certain standards. Generators
must complete a hazardous waste manifest to
accompany all shipments of hazardous waste
off site for treatment or disposal.
Generator recordkeeping and reporting
requirements are outlined in Subpart D of
Part 262 of the RCRA regulations (40 CFR
262.40 through 262.44). Large and small
quantity generator facilities must retain
signed copies of manifests for 3 years from
the date the waste was accepted by the initial
transporter. Generators must also keep
records of any test results, waste analyses, or
other required determinations for at least 3
years from the date the waste was sent for
processing. In addition, LQGs must submit a
biennial report that includes the following:
Summary of RCRA Requirements for
Hazardous Waste Generators
The facility must determine the quantity of
hazardous waste- generated on a monthly
basis.
Waste streams must be properly identified.
The facility must have an EPA Identification
number.
The facility must comply with all waste
accumulation requirements (40 CFR 262.34).
The facility must follow all waste manifest
requirements for off-site waste shipments
(40 CFR 262.420-423).
"The facility must retain copies of all
manifests, exception reports, biennial reports
(if required), records of test results, waste
analyses, and other required
determinations for at least 3 years.
'The EPA identification number, name, and address of the generator;
1 The EPA identification number, name, and address for each off-site treatment, storage,
and disposal facility to which waste was shipped during the year;
1 The EPA identification number and name of each transporter used;
Overview of Existing Regulations
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"A description, EPA hazardous waste number, DOT hazard class, and quantity of each
hazardous waste shipped off-site for shipments to a treatment, storage, or disposal facility;
. 3 '.-
"A description of efforts to reduce the volume and toxicity of the wastes generated; and
"A signed certification stating the information is true, accurate,'and complete.
Treatment, Storage, and Disposal Activities
Processors of zinc micronutrient-containing
hazardous waste must comply with certain
RCRA regulations. If the facility receives a
zinc micronutrient-containing waste from an
off-site generator and stores the waste for any
amount of time prior to using it in the fertil-
izer production process, it must have a
RCRA hazardous waste storage permit. If the
received waste is inserted directly into the
fertilizer production process (i.e., no storage
takes place) then a hazardous waste storage
permit is not needed. While the fertilizer
production process itself is not regulated By
RCRA, any handling or storage of the waste
prior to entering the fertilizer production
process must comply with the hazardous
waste management and storage require-
ments. The waste-derived fertilizer product is
not considered a hazardous waste, but
residues from its production might be.
Like generators, processors must keep signed
copies of all waste manifests for any haz-
ardous waste received or generated for at
least 3 years from the date of delivery. They
must also maintain an operating record,
which includes descriptions of waste quanti-
ties, dates received, and storage methods. The
closes. Processing facilities that store hazardous
the following:
Summary of RCRA Requirements for
Treatment, Storage, and Disposal Facilities
The facility must be permitted or licensed
to receive the zinc micronutrient-containing
hazardous waste.
Waste storage requirements must be met.
The facility must properly identify and
manage any hazardous wastes residues
from the processing of the zinc
micronutrient-containing waste during
the fertilizer production process.
The facility must retain copies of all
manifests, exception reports, and
biennial reports for at least 3 years.
The facility must maintain an operating
record.-
operating record must be maintained until the facility
waste must also submit a biennial report that includes
1 The EPA identification number, name, and address of the facility;
'The EPA identification number, name, and address for each generator that shipped haz-
ardous waste to the facility during the year;
"A description of the quantity of each hazardous waste received;
'A description of method of storage; and
'A signed certification.
Overview of Existing Regulations
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Land Disposal Restrictions
The land disposal restriction (LDR) program
was developed to protect groundwater. The
land disposal restrictions prohibit hazardous
waste from being placed on the land until the
waste is treated to reduce the mobility or toxic-
ity of its hazardous constituents. Once a haz-
ardous waste is generated, it becomes subject to
LDR.
EPA has developed LDR standards for almost
all hazardous Wastes that are land disposed. The
standards are expressed as concentrations in
leachate when tested according to the Toxicity
Characteristic Leaching. Procedure (TCLP) and
are generally technology-based standards.
TCLP was originally designed by EPA to simu-
late contaminants leaching from wastes in
municipal solid waste landfills4. LDR requires
sites to maintain notification and certification
paperwork to ensure the wastes are properly
managed.
Zinc micronutrient fertilizers produced from,
or containing, hazardous wastes are subject to
regulations for hazardous waste-derived prod-
ucts. These fertilizers can be manufactured
from several different types of zinc-bearing haz-
ardous wastes, such as dusts collected in emis-
sion control devices from electric arc furnaces
and brass foundries and ash from the combus-
tion of tires. These fertilizers can be made from
waste materials not classified as hazardous
wastes, as well as from raw materials such as
refined zinc ores24. For zinc micronutrient fer-
tilizers, the micronutrient processor converts
the hazardous waste into a -usable fertilizer. The
resulting ferdlizer is not considered a hazardous
waste as long as the LDR treatment standards
are met.
There are, however, exceptions to LDR. For
example, wastes are exempt if generated by
CESQGs. In addition, fertilizers produced
from K061 waste are exempt from the LDR
treatment standards at this time.
Summary of RCRA Requirements Under
the Land Disposal Restrictions Program
Waste Generator
The generating facility must send a
one-time notice to each facility that
receives its waste.
The generating facility must maintain
and follow a waste analysis plan if it
is treating its waste prior to shipment!
The generator must maintain copies of
all notices, certifications, waste analysis
data, and other related, documentation
for at least 3 years.
Micronutrient Processor
The processing facility must maintain
and follow a waste analysis plan
containing a detailed chemical and
physical analysis or any hazardous
waste treated on site.
The processing facility must submit a
certification to the appropriate official(s).
Proposed Changes to Federal
.Requirements
Federal requirements for RCRA, including
the land disposal restrictions program, are
currently undergoing review and possible
revision by EPA. For example, proposed
changes would establish technology-based
limits for the maximum amount of arsenic,
cadmium, chromium, lead, mercury, and
nickel allowed in zinc micronutrient fertilizer
and would establish a limit on the amount of
dioxins. Up-to-date information on these
changes can be found at:
http://www.epa.gov/epaoswer/hazwaste
recycle/fertiliz/index.htm.
Overview of Existing Regulations
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7.2 Hazard Communication Standard
The Occupational Safety and Health Administration (OSHA) also regulates the use of hazardous
waste-derived fertilizer products. The OSHA Haz'ara Corfiniunication .Standard (29 CFR Part
1910.1200) applies to chemical manufacturers and importers of "hazardous chemicals," including
agricultural operations. The'standard includes measures for warning workers about chemical hazards
through labels, material safety data sheets (MSDSs), other warning mechanisms and employee train-
ing. The standard does not apply to family members working on farms, only employees.
According to the standard, chemicals in concentrations of 1% or more (0.1% for carcinogens) must
be listed on the MSDSs for products used in the workplace. Manufacturers and importers must pro-
vide MSDSs for their products. Part 1910.1200 (b) (1) requires manufacturers or importers to assess
the hazards of chemicals which they produce or import. All employers must provide a hazard com-
munication program, labels and other forms of warning, MSDSs, and information and training to
educate employees about hazardous chemicals to which they are exposed4.
Part 1910.1200 (d) (1) states: "If a mixture has not been tested as a whole to determine whether the
mixture is a health hazard, the mixture shall be assumed to present the same health hazards as do the
components which comprise one percent (by weight or volume) or greater of the mixture, except that
the mixture shall be assumed to present a carcinogenic hazard if it contains a component in concen-
trations of 0.1 percent or greater which is considered to be a carcinogen under paragraph (d) (4) of
this section"4.
Chemicals subject to labeling requirements under specific acts such as the Federal Insecticide,
Fungicide and Rodenticide Act (FIFRA), the Toxic Substance Control Act (TSCA), and the Federal
Food, Drug, and Cosmetic Act (FFDCA), and consumer products regulated under the Consumer
Product Safety Act (CPSA) and the Federal Hazardous Substances Act (FHSA) are not required to fol-
low the MSDS requirement. Additionally, this section of the OSHA regulations does not apply to any
waste defined as hazardous under the Solid Waste Disposal Act (SWDA), as amended by the Resource
Conservation and Recovery Act (RCRA) and any hazardous substance defined by the Comprehensive
Environmental Response, Compensation and Liability Act (CERCLA) when the product is the focus
of remedial or removal action being conducted in accordance with EPA Regulations.
7.3 State Regulations
Most states regulate fertilizer composition for plant nutrients under state fertilizer regulatory pro-
grams. State laws generally require product registration and/or licensing and testing to assure that label
claims are valid. Most regulations also include statements about product adulteration and a prohibi-
tion against including any product that is harmful to plants, animals, humans, or the environment.
Only two states, Washington and Texas, have regulations that establish specific limits on heavy metal
contaminants and testing and labeling requirements.
Washington. In 1998, the State of Washington passed legislation requiring fertilizer manufacturers
to disclose the content of arsenic, cadmium, cobalt, mercury, molybdenum, lead, nickel, selenium,
and zinc in fertilizer products. Washington's Safe Fertilizer Act mandates certain requirements regard-
ing contaminant testing, registration and labeling, and contaminant standards. Washington estab-
lished standards for the maximum acceptable annual application of metals to soil. The standards were
derived from Canadian standards which specify long-term cumulative metals additions to soils.
Because the Canadian standards cover forty-five years, the annual standards developed for Washington
were developed by dividing the Canadian standards by forty-five. The Washington standards are list-
ed in Table 7-1.
Overview of Existing Regulations
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Table 7-1 Washington Standard for
Annual Metal Additions to Soil
Maximum Acceptable Annual
Application (Ibs/acre/year)
Arsenic
Cadmium
Cobalt
Mercury
Molybdenum
Nickel
Lead
Selenium
Zinc
0.297
0.079
0.594
0.019
0.079
0.713
' 1.981
0.055
7.329
Source: Washington State Department of Agriculture
Cobalt, molybdenum, and zinc are considered plant nutrients and can be applied at rates greater than
those shown in Table 7-1 if they are guaranteed on the label. If any of those three metals are not meant
for use by the plants to which the product is applied, then those metals must meet the state standards28.
In addition to meeting the standards listed in Table 7-1, plant nutrients other than nitrogen, phos-
phorus, and potassium must be guaranteed on the label. Guarantees ensure that the nutrient has been
registered with the state and must include the nutrient source28. If a fertilizer or any part of a fertilizer
is derived from solid or hazardous wastes, the fertilizer is defined as being waste-derived and must be
identified as such. For more information on the State of Washington's program, go to
http:llwww.ecy.wa.govlprogramslhwtr/fertilizer/index.htm. .
Texas. The State of Texas has regulations analogous to those of Washington. However, Texas based
their limits on EPA's standards for sewage sludge (40-CFR Part 503). Texas commercial fertilizers must
meet allowable concentration limits for trace elements or annual loading rates for trace elements,
shown in Table 7-2. For more information on the State of Texas' program, go to
httf./lotscweb. tamii. edu/.
Overview of Existing Regulations
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Table 7-2 State of Texas Limitations for Commercial Fertilizers
1 I !
Pollutant Maximum Allowable Concentration of Trace Cumulative Element
Elements in Commercial Fertilizers ( ppm) Loading Rate (Ibs/acre/year)
i
Arsenic
Cadmium
Copper
Lead
Mercury
Molybdenum
Nickel
Selenium
Zinc
41
39
1500*
300
17
18* -
420
100*
2800*
0.37
0.35
13..4*
2.68
0.15
0.16*
3.75
0.89*-
25.0*
*These elements may be required at higher concentrations for plant growth. Fertilizers containing concentrations of these elements at levels
higher than the maximum must be guaranteed.
Source: Texas §65, Tables 1 and 2. , " ,
Other States. Pennsylvania requires testing and approval from the Department of Environmental
Protection before selling fertilizers made from industrial waste products4.
7.4 International Regulations
International fertilizer regulations differ from United States laws in content and enforcement. Canada
limits concentrations of heavy metals in fertilizer products, while Japan limits the heavy metal and
organic chemical content in incinerator ash from industrial and municipal waste treatment incinera-
tors. The European Union has fertilizer regulations that all member nations are required to follow.
Canadian Fertilizer Act. The Canadian Fertilizers Act R.S., c. F-9, s.l (1993) and Fertilizers
Regulations contain metal limits used by the Canadian Food Inspection Agency. The limits apply to
all fertilizers and soil supplements sold in Canada. Developed in 1978 and revised in 1980, the limits
were intended for the land application of biosolids4. Table 7-3 shows the limits for the metals in fer-
tilizer and soils following the application of fertilizers. The limits are designed to be cumulative limits
over a 45-year period. The standards were designed to be conservative since significant concentrations
are already present in the soil in some areas29. .
Overview of Existing Regulations
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Table 7-3 Canadian Maximum. Acceptable Cumulative
Metal Additions to Soil and Maximum
Acceptable Metal Concentration in Products
Cumulative Metal Addition
to Soil, 45-year period (kg/ha)
Arsenic
Cadmium
Cobalt
Mercury
Molybdenum
Nickel
Lead
Selenium
Zinc
15
4
30
1
4
- 36
100
2.8
370
Source: EPA.1999
All micronutrient fertilizers, fertilizer/pesticide mixes, and most supplements must be registered
through the Canadian Food Inspection Agency (CFIA). A product can become registered after the
manufacturer has submitted metal analyses and the levels are shown to be below the Canadian limits.
Non-registered fertilizers are randomly selected for metal analyses. Products exceeding metal limits can
be detained and seized4.
Canadian regulations also control the labeling of micronutrient fertilizers. They require the identifica-
tion and description .of the product and its constituents, the industrial process from which the prod-
uct is derived, the benefits of the product, rates and methods of application, and documented analy-
ses for heavy metals, dioxins, and furans4. For more information on Canada's program, go to
http:llinspection.gc. calenglishlplaveglferenglferenge. html.
European Union Requkements. The European Union directive on fertilizers concerns fertilizer con-
tent and package markings. In a simplified form it is similar to the U.S. EPA rules. While not provid-
ing guidance on limits of contaminants in the environment, the directive includes the following state-
ment:
"Member States shall take the necessary measures to ensure that waste is recovered or disposed of
without endangering human health and without using processes or methods which could harm the
environment."
Overview of Existing Regulation's
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References
1. Martens, D.C. and D.T. Westermann. "Fertilizer Applications for Correcting Micronutrient
Deficiencies." In: SSSA Book Series: 4, Micronutrients in Agriculture, J.J. Mortvedt, F.R. Cox,
L.M. Shuman, and R.M. "Welch, eds. Soil Science Society of America, Inc. Madison, WI, 1991.
pp. 703-723.
2. Mortvedt, J.J. "Micronutrient Fertilizer Technology." In: SSSA Book Series: 4, Micronutrients in
Agriculture, J.J. Mortvedt, F.R. Cox, L.M. Shuman, and R.M. Welch, eds. Soil Science Society of
America, Inc. Madison, WI, 1991. pp. 523-548.
3. Telephone conversations with Paul B. Queneau, P.B. Queneau & Associates Inc., 4 and 23
October 2000.
4. U.S. EPA. "Background Report on Fertilizer Use, Contaminants and Regulations." 747-R-98-
003, January 1999.
5. U.S. EPA. Inside EPA. Vol. 21, No. 49, 8 December 2000. :
6. Telephone conversation with Paul A. Borst, U.S. EPA, 4 October 2000.
7. Telephone conversations with Dick Camp, Bay Zinc Corporation, 25 October and 1 November
2000. ~ '
8. U.S. EPA. "Economic Analysis for Regulatory Modifications to the Definition of Solid Waste for
Zinc-Containing Hazardous Waste-Derived Fertilizers, Notice of Proposed Rulemaking: Final
Report"-November 2000k
9. American Iron and Steel Institute (AISI). Steel Industry Technology Roadmap.
http-.llwww.steel.org/mt/roadmap/roadmap.htm. Accessed December 2000.
10. Lindblad, B. and E. Burstrom. A Scandinavian View On Coated Scrap and the Environment.
Lulea, Sweden: MEFOS.
11. Acharya, P., S.G. DeCico, and R.G. Novak. "Factors that Can Influence and Control the
Emissions of Dioxins and Furans From Hazardous Waste Incinerators." Journal of Air Waste
ManagementAssoc. 41:12 (1991): 1605-1615.
12. U.S. EPA. "Universal Treatment Standards." 40 CFR §268.48.
13. Telephone conversation with Carl Schauble, Frit Industries, 24 October 2000.
14. Petition of Horsehead Resource Development Company, Inc., for an adjusted standard under
35 111. Adm. Code 720.131© before Illinois Pollution Control Board, 28 October 1999.
15- Michels, H.T. "Understanding Copper-based Alloy," Engineered Casting Solutions. American
Foundry Society. Summer edition, 2000. pp. 54-57.
16. Telephone conversation with Steve Robinson, American Foundries Society, 8 December 2000.
References
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17. Telephone conversation with a representative of Foundry Products Supplier C, 28 November
2000.
18. U.S. EPA, et al. Development Document for the Effluent Limitations Guidelines and Standards for
the Foundries (Metal Molding and Casting) Point Source Category. EPA440-l-80-070a. Washington,
DC, April 1980.
19. Schleg, E and D. Kanicke. "Guide to Casting and Molding Processes." Engineered Casting
Solutions. American Foundry Society. Summer edition, 2000. pp. 18-27.
20. U.S. EPA. "Requirements for Zinc Fertilizers Made From Recycled Hazardous Secondary
Materials; Proposed Rule." 40 CFR § 261, 266, and 268. 28 November 2000.
21. Lankford, W.T. Jr., N.L. Samways, R.F. Craven, H.E. McGannon, eds. The Making, Shaping and
Treating of Steel, 10th Edition. Herbick & Held, Pittsburgh, PA, 1985-
22. "Land Application of Hazardous Waste Derived Micronutrient Fertilizers," Bay Zinc Company
and Tetra Technologies, Inc., 19 November 1999.
23. Queneau, Paul B. "Fertilizer and Feed." Recycling Metals from Industrial Wastes Workshop.
Colorado School of Mines, Golden, CO, June 1999.
24. "EPA Rule Making RE: Secondary Zinc Oxides Used in the Production of Fertilizer
Ingredients," Big River Zinc Corporation Position Paper.
25. Northeast Regional Agricultural Engineering Services (NRAES). Fertilizer and Manure
Application Equipment, NRAES-57. 1994.
26. U.S. EPA. Estimating Risk from Contaminants Contained in Agricultural Fertilizers: Draft Report.
Washington, DC, 1999. http://www.epa.gov/epaoswer/hazwaste/recycle/fertiliz/risk/index.htm.
27. U.S. EPA. "Hazardous Waste Recycling; Land Disposal Restrictions; Final Rule." Fed. Reg. 63:
168. 31 August 1998.
28. Washington State Department of Agriculture. Rules Relating to Fertilizers, Minerals, and Limes.
1 May 1999. '
29. Canadian Food Inspection Agency (CFIA). Guidelines to the Fertilizers Act and Regulations, Plant
Health and Production Division Plant Products Directorate Canadian Food Inspection Agency,
http://www.cfia-acia.agr.ca/english/plaveg/fereng/guide.html. Accessed 6 October 2000.
References
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