U.S. Department of the Interior

U.S. Geological Survey

Tungsten Recycling in the United States in 2000

By Kim B. Shedd

U.S. GEOLOGICAL SURVEY CIRCULAR 1196–R

SUPERSEDES OPEN-FILE REPORT 2005–1028

FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES
II

U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2011

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Shedd, K.B., 2011, Tungsten recycling in the United States in 2000, chap. R of Sibley, S.F., Flow studies for recycling metal commodities in the United States: U.S. Geological Survey Circular 1196–R, p. R1–R19, available only at 

http://pubs.usgs.gov/circ/circ1196-R/. (Supersedes U.S. Geological Survey Open-File Report 2005–1028.)
III

FOREWORD

As world population increases and the world economy expands, so does the demand 

for natural resources. An accurate assessment of the Nation’s mineral resources must 

include not only the resources available in the ground but also those that become available 

through recycling. Supplying this information to decisionmakers is an essential part 

of the USGS commitment to providing the science that society needs to meet natural 

resource and environmental challenges.

The U.S. Geological Survey is authorized by Congress to collect, analyze, and 

disseminate data on the domestic and international supply of and demand for minerals 

essential to the U.S. economy and national security. This information on mineral 

occurrence, production, use, and recycling helps policymakers manage resources wisely.

USGS Circular 1196, “Flow Studies for Recycling Metal Commodities in the 

United States,” presents the results of flow studies for recycling 26 metal commodities, 

from aluminum to zinc. These metals are a key component of the U.S. economy. Overall, 

recycling accounts for more than half of the U.S. metal supply by weight and roughly 

40 percent by value. 

Marcia K. McNutt

Director
IV

CONTENTS

Foreword .......................................................................................................................III

Abstract........................................................................................................................R1

Introduction.....................................................................................................................1

Global Geologic Occurrence of Tungsten..................................................................3

Tungsten Production Processes..................................................................................4

Uses............................................................................................................................4

Prices..........................................................................................................................6

Sources of Tungsten Scrap..............................................................................................8

Old Scrap Generated ..................................................................................................8

New Scrap ..................................................................................................................9

Scrap Imports...........................................................................................................10

Disposition of Tungsten Scrap......................................................................................10

Scrap Consumption (Recycling and Recovery) .......................................................10

Scrap Exports...........................................................................................................10

Unrecovered Old Scrap ............................................................................................11

Dissipation................................................................................................................11

Old Scrap Recycling Efficiency....................................................................................11

Infrastructure of Tungsten Scrap Industry ....................................................................11

Alloy Scrap...............................................................................................................12

Cemented Carbide Scrap..........................................................................................12

Mill Products From Metal Powder Scrap.................................................................12

Processing of Tungsten Scrap .......................................................................................12

Cemented Carbide Scrap..........................................................................................13

Heavy Metal Alloy Scrap.........................................................................................13

Mill Products From Metal Powder Scrap.................................................................14

Residues...................................................................................................................14

Spent Catalysts.........................................................................................................14

Steel and Specialty Alloy Scrap...............................................................................14

Thoriated Tungsten Scrap ........................................................................................14

Outlook .........................................................................................................................15

References Cited ...........................................................................................................15

Appendix—Definitions.................................................................................................18
V

FIGURES

1. Flow diagram showing the U.S. tungsten materials flow in 2000 .................R2

2. Simplified flow sheet for a modern tungsten conversion plant.........................5

3. U.S. tungsten consumption by end-use sector from 1980 through 2000..........6

4. Free market ammonium paratungstate prices from 1990 through 2000...........7

5. U.S. spot cobalt cathode prices from 1990 through 2000.................................8

TABLE

1. Salient statistics for U.S. tungsten scrap in 2000 ..........................................R1

CONVERSION FACTORS

Multiply By To obtain

Mass

kilogram (kg) 2.205 pound (lb)

metric ton (t, 1,000 kg) 1.102 short ton (2,000 pounds)

ton, short (2,000 lb) 0.9072 megagram (Mg)

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=(1.8×°C)+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F–32)/1.8

R1

FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

Tungsten Recycling in the United States in 2000

By Kim B. Shedd

ABSTRACT

This report, which is one of a series of reports on metals 

recycling, defines and quantifies the flow of tungsten-bearing 

materials in the United States from imports and stock releases 

through consumption and disposition in 2000, with particular 

emphasis on the recycling of industrial scrap (new scrap) and 

used products (old scrap). Because of tungsten’s many diverse 

uses, numerous types of scrap were available for recycling by 

a wide variety of processes. In 2000, an estimated 46 percent 

of U.S. tungsten supply was derived from scrap. The ratio of 

tungsten consumed from new scrap to that consumed from 

old scrap was estimated to be 20:80. Of all the tungsten in old 

scrap available for recycling, an estimated 66 percent was either 

consumed in the United States or exported to be recycled.

INTRODUCTION

The purpose of this report is to define and quantify 

the recycling1

 of tungsten-bearing scrap, which represents 

an important component of total tungsten supply. Figure 1 

illustrates the flow of tungsten in 2000. It shows sources and 

distribution of U.S. tungsten supply with particular emphasis on 

the flow of tungsten-bearing scrap. Table 1 lists salient tungsten 

scrap statistics for 2000.

Tungsten is a whitish-gray metal with a wide variety of 

commercial, industrial, and military uses that result from its 

unique mixture of properties—it is one of the heaviest metals 

and has the highest melting point of any element except carbon, 

excellent high-temperature mechanical properties, the lowest 

expansion coefficient of all metals, the lowest vapor pressure 

of all metals, very high moduli of compression and elasticity, 

very high thermal creep resistance, high thermal and electrical 

conductivity, and a very high coefficient of electron emission 

(International Tungsten Industry Association, 1997, p. 2).

1

Definitions for selected words are found in the appendix.

Table 1. Salient statistics for U.S. tungsten scrap in 2000.

[Values in metric tons of contained tungsten unless otherwise specified]

Old scrap:

Generated1............................................................... 7,300

Consumed2 .............................................................. 6,200

Consumption value3 ................................................... $35 million

Recycling efficiency4.................................................. 66 percent

Supply5 ................................................................... 9,700

Unrecovered6............................................................ 3,300

New scrap consumed7 ...................................................... 1,600

New-to-old-scrap ratio8 .................................................... 20:80

Recycling rate9 ............................................................... 46 percent

U.S. net imports of scrap10................................................. 2,940

Value of U.S. net imports of scrap ....................................... $15 million

1

Old scrap generated is estimated to have been the tungsten content of products theoretically becoming obsolete in the United States in 2000.

2

Old scrap consumed is estimated to have been the tungsten content of used 

products that were recycled in 2000.

3

Value of tungsten contained in old scrap, which was based on estimated 

quantities and estimated values of cemented carbide and noncemented carbide 

scrap.

4

Recycling efficiency is (old scrap consumed plus old scrap exported) 

divided by (old scrap generated plus old scrap imported plus any old scrap 

stock decrease or minus any old scrap stock increase).

5

Old scrap supply is old scrap generated plus old scrap imported plus old 

scrap stock decrease.

6

Old scrap unrecovered is old scrap supply minus old scrap consumed 

minus old scrap exported minus old scrap stock increase.

7

New scrap consumption includes prompt industrial scrap but excludes 

home scrap.

8

New-to-old-scrap ratio is the ratio of quantities consumed, expressed as a 

percentage.

9

Recycling rate is the fraction of the apparent tungsten supply that is scrap, 

on an annual basis. It is defined as (consumption of old plus consumption of 

new scrap) divided by apparent supply; measured in weight and expressed as 

a percentage.

10Net imports of scrap are tungsten contained in imports minus tungsten 

contained in exports of scrap. Tungsten-bearing scrap imports are estimated 

to be approximately 25 percent new scrap and 75 percent old scrap; tungstenbearing scrap exports are assumed to be principally old scrap.
R2 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES DOMESTIC SUPPLY OF UNWROUGHT PRIMARY AND SECONDARY TUNGSTEN DISTRIBUTION OF DOMESTIC TUNGSTEN SUPPLY Release of industry and Government stocks of tungsten materials, excluding scrap Imports of unwrought tungsten materials, excluding scrap 8,930 2,150 Old scrap consumed 6,200 New (prompt) scrap consumed 1,600 New 

scrap 

imports 

800 

New 

scrap stock 

decrease 

30 

Production of tungsten metal 

powder and tungsten carbide 

powder 

Processing 

losses 

600 

Home and 

prompt (new) 

scrap 

Old scrap 

supply 

9,700 

Old scrap 

imports 

2,300 

Old scrap 

stock 

decrease 

70 

Old scrap 

exports 

160 

Unrecovered 

old scrap 

3,300 

Tungsten 

products 

reservoir 

net change 

+7,600 

Exports of unwrought 

tungsten materials, 

excluding scrap 

1,640 

Fabrication of tungsten 

products 

Home 

scrap 

Processing 

losses 

500 

Tungsten 

products to 

U.S. market 

15,200 

New (prompt) scrap 

generated 

770 

Dissipative 

uses 

300 

Net exports of 

wrought 

products 

137 

imports 

260 

exports 

397 

770 

NA 

500 

15,200 

16,600 

1,640 

18,300 

14,900 

7,300 

7,300 

2,300 

70 

NA 

160 3,300 

30 800 

1,600 

6,200 

6,200 

2,150 

8,930 

10,400 9,800 

18,900 

770 

300 770 

Old scrap generated:

Cemented carbide parts . . . 5,700Lighting components . . . . . . . 600Spent catalysts . . . . . . . . . . . . . W

Steel, alloy, and tungsten metal 

products . . . . . . . . . . . . . . 1,000

Total . . . . . . . . . . . . . . . . 7,300

data. proprietary y compan

wn.

disclosing 

o

oid vato withheld , Wvailable; anot A, N2000. in w flomaterials tungsten U.S. the wing shodiagram w Flo 1.e Figur

Values are in metric tons of contained tungsten, are rounded to no more than three significant digits, and may not add to totals sh
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R3

GLOBAL GEOLOGIC OCCURRENCE OF 

TUNGSTEN

The average concentration of tungsten in the Earth’s 

crust is estimated to be approximately 0.0001 percent (1 

part per million). Although tungsten is present in more than 

20 mineral species, only two are commercially important—

scheelite and wolframite. Scheelite, which is sometimes 

referred to as “white ore,” is calcium tungstate (CaWO4). 

Wolframite, which is sometimes referred to as “black ore,” 

is the name for a mineral and the mineral group to which it 

belongs. The wolframite group is a solid solution series of 

iron- and manganese-rich tungstates [(Fe,Mn)WO4]. In this 

series, tungstates with more than 80 percent FeWO4 are called 

ferberite; tungstates with more than 80 percent MnWO4, 

huebnerite; and tungstates with between 20 and 80 percent of 

each of FeWO4 and MnWO4, wolframite (Hobbs and Elliott, 

1973; Yih and Wang, 1979, p. 2–6, 22; Werner and others, 

1998, p. 3; Lassner and Schubert, 1999, p. 65–70).

Tungsten deposits occur in a wide variety of geologic 

environments, which range from high-temperature deepseated deposits associated with igneous intrusions to 

relatively low-temperature surface deposits associated with 

hot springs. Tungsten minerals can also be found in placer 

deposits, and tungsten-bearing brines and evaporites occur 

in certain arid regions. Because most tungsten deposits 

are associated with granitic igneous activity, many share 

common features, and as a result, there are several different 

ways of classifying them. One classification (Werner and 

others, 1998), which was used by an international committee 

convened to gather information on major sources of mineral 

raw materials, classifies most producing tungsten mines into 

the following four deposit types: vein/stockwork, skarn, 

porphyry, and strata-bound, which are listed in order of share 

of production from highest to lowest in the mid-1980s. The 

descriptions below were based on information from Hobbs 

and Elliott (1973), Yih and Wang (1979, p. 9–22, 49–50), 

Thalhammer and others (1989, p. 1153, 1158, 1160), and 

Werner and others (1998, p. 4–9).

Vein/stockwork deposits typically consist of tungstenbearing quartz veins or vein stockworks that occur in or near 

granitic intrusions. The veins are tabular bodies that vary 

greatly in length, width, and depth and consist of quartz, 

scheelite and (or) wolframite, and minor amounts of other 

minerals. Most vein deposits are relatively small, on the order 

of a few hundred thousand metric tons of ore. Stockworks are 

three-dimensional networks of closely spaced veins, veinlets, 

or fracture-fillings that can be mined by bulk methods. In 

contrast to skarn deposits described below, the host rocks 

associated with this class of deposit usually contain little, if 

any, carbonates.

Skarn deposits are formed by high-temperature 

replacement and recrystallization of limestone or dolomite 

at or near contacts with granitic intrusions. The resulting 

calcium silicate rocks are called skarns or tactites. When 

present in this type of deposit, tungsten is in scheelite or 

molybdenum-bearing scheelite, which can occur in veinlets 

or fractures or as disseminated grains. Skarn deposits range 

in size from hundreds to millions of metric tons of ore. This 

type of deposit is also called tactite, contact metamorphic, 

contact metasomatic, or pyrometasomatic.

Porphyry tungsten deposits are large equidimensionalto-irregular stockworks that occur in or near epizonal-tosubvolcanic felsic granitic intrusions. Tungsten occurs in 

wolframite and (or) scheelite in veins, veinlets, and fractures. 

Molybdenum is commonly present, sometimes in high 

enough concentrations to be a viable byproduct or coproduct. 

Mineralized breccia zones may be present. This type of 

deposit is generally large and contains tens to hundreds 

of millions of metric tons of ore but has a low average 

tungsten grade. Some of the specific deposits that fall into 

this category sometimes are classified as greisen deposits. 

As with porphyry tungsten deposits, greisen alteration is 

associated with granitic intrusions. It is distinguished by a 

given suite of alteration minerals, such as muscovite, quartz, 

topaz, and tourmaline. Tin and molybdenum can be present 

in economic concentrations.

Strata-bound deposits are those in which the distribution 

of tungsten minerals is strongly controlled by bedding in the 

host rock. They range in size from one to tens of millions of 

metric tons of ore. One example is the ore of the Mittersill 

Mine in Austria where scheelite occurs in quartz veins, 

lenses, and quartz-rich rocks that are parallel on the large 

scale to the planar texture of the metamorphosed host rocks. 

In this deposit, some of the tungsten-rich quartz veins also 

crosscut the texture of the host rocks.

In 2000, production of tungsten concentrates was not 

recorded in the United States. China, which was the world’s 

leading producer, represented an estimated 84 percent of 

total concentrate production. Chinese tungsten production 

came from numerous mining areas that represented a wide 

variety of deposit types that contained scheelite, wolframite, 

and mixed scheelite-wolframite ores. A survey of 60 Chinese 

tungsten mines indicated that 95 percent of Chinese production 

was from Guangdong, Guangxi, Hunan, Jiangxi, and Yunnan 

Provinces. Russia contributed an estimated 8 percent of 

world tungsten concentrate production. This production was 

primarily scheelite from greisens and skarns at one mine in 

the Caucasus Mountains in western Russia and two mines in 

Primorskiy Kray in southeastern Russia. Other countries that 

produced more than 300 metric tons per year (t/yr) of tungsten 

in concentrates in 2000 included Austria where scheelite was 

mined from the Mittersill strata-bound deposit described 

above, Bolivia where wolframite was mined by small- and 

medium-scale mining entities and cooperatives from vein/

stockwork and possibly other types of deposits, Portugal 

where wolframite was mined from a vein-type deposit, and 

possibly North Korea (Yih and Wang, 1979, p. 20, 49–51, 53; 
R4 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

APT can be calcined under reducing conditions to form 

tungsten blue oxide, which is a mixture of tungsten oxides 

and other constituents; calcined under oxidizing conditions 

to form tungsten trioxide; decomposed by hydrochloric 

acid to form tungstic acid; or subjected to partial thermal 

decomposition to form ammonium metatungstate. Tungsten 

blue oxide is the most commonly used starting material to 

make tungsten metal powder, which is used to make tungsten 

alloys, tungsten carbide powder, and tungsten metal. Tungsten 

trioxide can be used to make tungsten metal powder and is 

also used as a yellow pigment. Tungstic acid is used to make 

tungsten chemicals and ultrafine tungsten metal and tungsten 

carbide powders. Ammonium metatungstate is used to make 

tungsten chemicals and tungsten-bearing catalysts (Lassner 

and Schubert, 1999, p. 208–215).

Some tungsten ore concentrates are processed directly 

to tungsten carbide. In one process, which is alternatively 

referred to as the “macrocrystalline,” “macro,” or “thermit” 

process, a mixture of tungsten ore concentrates and iron 

oxide are reduced by aluminum metal and simultaneously 

carburized by calcium carbide or carbon. The reactants 

are proportioned and added at a rate to create a selfsustaining exothermic reaction. This process forms coarse 

macrocrystalline tungsten carbide, which can be used in 

hardfacing applications and diamond tool matrices and 

following milling to reduce particle size to make cemented 

carbide tips for mining tools (Smith, 1980).

Tungsten ore concentrates can also be used to make 

ferrotungsten, which is a master alloy used in the production 

of steel. Ferrotungsten can be made using either carbothermic 

or carbothermic-silicothermic reduction in an electric 

arc furnace (EAF) or metallothermic reduction. Artificial 

scheelite and soft tungsten scrap also can be used as raw 

materials to make ferrotungsten. Tungsten melting base, 

which is another master alloy used in steelmaking, is made 

by reducing tungsten-bearing scrap in an EAF (Lassner and 

Schubert, 1999, p. 309–312).

USES

In 2000, tungsten was used in many diverse commercial, 

industrial, and military applications. The leading use was 

as tungsten carbide in cemented carbides. These materials, 

which are also referred to as “hardmetals,” are sintered 

powder metallurgical parts that are used as cutting tools 

and wear-resistant components by the construction, 

metalworking, mining, and oil drilling industries. In making 

these parts, cobalt or nickel metal powder is used as a binder 

to hold together the tungsten carbide grains. Tungsten alloy 

or pure tungsten metal contacts, electrodes, and wires are 

used in electrical, electronic, heating, lighting, and welding 

applications. Tungsten is also used to make heavy metal alloys 

for armaments, heat sinks, radiation shielding, and weights 

and counterweights; superalloys for turbine parts; tool steels; 

Rabchevsky, 1988, p. 25–26, 38–39; Werner and others, 1998, 

p. 29–30, 32–35, 40, 44–45; Zhaoqing and Pugang, 1999; 

Zhaoqing and others, 2001; Velasco, 2002; Visser, 2002, p. 4, 

15–16; Walser, 2002, p. 1–5; Shedd, 2003b, p. 80.18).

TUNGSTEN PRODUCTION PROCESSES

Most tungsten is mined from relatively small 

underground mines. A few tungsten mines have used open pit 

methods to access near-surface ores, but in most cases, these 

mines were later converted to underground mines to access 

deeper ores. Conventional underground mining methods, 

such as open stoping, shrinkage stoping, room-and-pillar 

stoping, sublevel stoping, sublevel caving, block caving, 

cut-and-fill, and square set, are used. The method used for 

a particular mine depends on the size, shape, and attitude of 

the ore body; the competence of the ore zone and wall rocks; 

and the continuity and grade of the ore body (Yih and Wang, 

1979, p. 25; Rabchevsky, 1988, p. 11; Bernhardt, 1998, p. 

1; Correa de Sá and Naique, 1998, p. 6–8). Tungsten ores 

are crushed, ground, and then concentrated by a combination 

of gravimetric, flotation, and (or) magnetic methods. Where 

necessary, preconcentration by ore sorting, the use of jigs, or 

heavy media separation; leaching; roasting; and high-tension 

(electrostatic) separation are also used in the beneficiation of 

tungsten ores (Yih and Wang, 1979, p. 55–57; Lassner and 

Schubert, 1999, p. 179–184).

Most tungsten ore concentrates are processed chemically 

to produce ammonium paratungstate (APT), which is the 

main tungsten raw material traded in the market. In modern 

tungsten conversion plants, scheelite concentrates, wolframite 

concentrates, and soft or hard tungsten scrap can be used as 

raw materials. Before processing, ore concentrates may need 

to be calcined, leached, roasted, and (or) ground to a smaller 

particle size. Soft scrap is heated in air or oxygen-enriched air 

to oxidize the tungsten to the hexavalent state so that it will 

dissolve easily under alkaline conditions. The oxidized scrap 

is then ground and screened before leaching. Hard scrap can 

be treated by one of two methods. It can be fused or roasted 

in the presence of an oxidizing agent and a diluent, then 

cooled, crushed, and dissolved in water, or it can be treated 

by electrolysis. Electrolysis uses the scrap as an anode in a 

solution of sodium hydroxide or sodium carbonate. It results 

in a solution of sodium tungstate and insoluble oxides or 

oxide hydrates of the other elements that were present in the 

scrap. The remaining steps to produce APT are outlined in 

figure 2 (Lassner and Schubert, 1999, p. 184–193).

The importance of scrap as a raw material in APT 

production was indicated by statistics compiled by the 

International Tungsten Industry Association. In 2001, an 

estimated 70 percent of the APT produced by companies that 

contributed data for Europe, Japan, and the United States was 

derived from scrap. The remaining 30 percent was derived 

from ore concentrates (Maby, 2002, p. 5).
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R5

Figure 2. Simplified flow sheet for a modern tungsten conversion plant. 

Reprinted from Lassner and Schubert (1999) and published with permission from 

Kluwer Academic/Plenum Publishers.

and wear-resistant alloy parts and coatings. Tungsten alloys 

and tungsten composites are used as a substitute for lead 

in bullets and shot. Tungsten chemicals are used to make 

catalysts, corrosion-resistant coatings, dyes and pigments, 

fire-resistant compounds, high-temperature lubricants, and 

phosphors. They are used as chemical reagents and as a 

source of tungsten metal in the manufacture of semiconductor 

devices. Most of the chemical applications are considered 

to be dissipative—the tungsten represents an important but 

very minor constituent of the final product, which is widely 

distributed during use. This makes tungsten reclamation or 

recycling impractical or impossible. One exception is the use 

of tungsten in catalysts, which are products that are sometimes 

recycled, as discussed in the section “Spent Catalysts.”

The United States is a significant consumer of tungsten 

materials. On the basis of data reported to the U.S. Geological 
R6 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

Survey (USGS), U.S. tungsten consumption in 2000 can be 

divided into the following end-use categories: cemented carbides 

(60–65 percent); steels and other alloys (15–20 percent); 

mill products, such as contacts, electrodes, and wires (15–20 

percent); and chemical uses (approximately 1 percent). Actual 

consumption in chemical applications is likely to be higher than 

that reported to the USGS. Other estimates place U.S. tungsten 

use in chemical products at 3 to 4 percent of total U.S. tungsten 

consumption (International Tungsten Industry Association, 

1997, p. 3; Payne, 2002, p. 8; Shedd, 2002, p. 81.8).

Figure 3 shows trends in U.S. consumption of tungsten 

by various industry sectors since 1980. Trends in total 

tungsten consumption are strongly influenced by general 

economic trends, industrial activity, and trends in cemented 

carbide production, which is the leading consuming industry 

sector. The cemented carbide industry is influenced by 

the performance of the following industries: aerospace, 

automotive, construction, electronics, general manufacturing, 

large equipment manufacturing, mining, and oil and gas 

drilling (Payne, 2002, p. 8–10). Consumption by the other 

industry sectors presented in figure 3 was relatively consistent 

during the past two decades. Some of the sudden changes in 

consumption, either increases or decreases, are the result of 

changes in the number of companies that reported data to the 

U.S. Bureau of Mines (USBM) or the USGS.

PRICES

Prices of tungsten-bearing scrap are not published on 

a routine basis. Historically, the main reference price for 

tungsten was the price of tungsten concentrates. In the early 

1990s, trade in tungsten concentrates decreased, and APT 

became the most widely traded primary tungsten material. As 

a result, the price of APT has become the reference price for 

upstream materials, such as tungsten ore concentrates, and 

downstream materials, such as tungsten metal powders and 

tungsten carbide powders (International Tungsten Industry 

Association, 1997, p. 32; Ross, 2001, p. 5). The price of APT 

is quoted in units of tungsten trioxide (WO3). The short ton 

unit, which is used in the United States, is 1 percent of a short 

ton (20 pounds), and WO3 contains 79.3 percent tungsten. 

Therefore, a short ton unit of WO3 equals 20 pounds of WO3

and contains 7.19 kilograms (kg) (15.86 pounds) of tungsten. 

The metric ton unit, which is used in most other countries, is 

0

2,000

4,000

6,000

8,000

10,000

12,000

YEAR

CONSUMPTION, IN METRIC TONS

Figure 3. U.S. tungsten consumption by end-use sector from 1980 through 2000. Values are in metric tons of 

contained tungsten.
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R7

1 percent of a metric ton (10 kg). A metric ton unit of WO3

contains 7.93 kg (17.48 pounds) of tungsten.

Historically, tungsten prices have fluctuated widely with 

the fluctuation of the market between periods of scarcity 

and oversupply (Shedd, 1999b). Figure 4 presents U.S. free 

market prices of APT for 1990 and European free market 

prices for 1991 through 2000 as reported in Metal Bulletin. 

During this time period, the price of APT fluctuated widely 

between a low of $32 per metric ton unit ($4 per kilogram of 

contained tungsten) and a high of $100 per metric ton unit 

($13 per kilogram of contained tungsten). During the first half 

of 2000, the price reached a low of $49 per metric ton unit 

($6 per kilogram of contained tungsten). During the second 

half of the year, the price rapidly increased to $86 per metric 

ton unit ($11 per kilogram of contained tungsten) as a result 

of efforts by China, which was the world’s leading tungsten 

supplier, to reform its industry and control the exports of 

tungsten materials from China (Shedd, 2002, p. 81.3–81.4).

To a certain extent, the price of cobalt influences the 

recycling rate of tungsten. Higher prices for cobalt encourage 

the recycling of cemented carbides, which contain cobalt and 

tungsten. During periods of low cobalt prices, recycling of 

cobalt-bearing scrap decreases, and more primary tungsten 

raw materials are consumed (Maby, 2002, p. 5). Since the late 

1970s, free market prices for cobalt have varied considerably 

(Shedd, 1999a). During the 1990s, the U.S. spot price for 

cobalt cathode (minimum of 99.8 percent cobalt), as reported 

in Platt’s Metals Week, fluctuated widely between a low of 

$7.50 per pound ($16.50 per kilogram) and a high of $35 

per pound ($77 per kilogram) (fig. 5). Although this price 

varied significantly during the course of each year, the annual 

average price has trended downward from 1995 to 2000. 

During 2000, the U.S. spot cathode price fluctuated between 

$13 and $18 per pound ($29 and $40 per kilogram).

Figure 4. Free market ammonium paratungstate prices from 1990 through 2000. Data are from various issues of Metal Bulletin.
R8 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

Figure 5. U.S. spot cobalt cathode prices from 1990 through 2000. Data are from various issues of Platt’s Metals Week.

SOURCES OF TUNGSTEN SCRAP

Sources of tungsten scrap are key features of the U.S. 

tungsten materials flow shown in figure 1. Domestic scrap 

originates during manufacturing and following use of 

products in the United States. Scrap generated in foreign 

countries can enter the United States as imports.

OLD SCRAP GENERATED

Old scrap consists of tungsten-bearing products that 

are no longer being used. Some examples of used cemented 

carbide parts include metal cutting tools, such as burs, drill 

bits, end mills, form cutters, gundrills, inserts, reamers, saw 

tips, shim seats, and threading and grooving tools; metal 

forming tools, such as can tooling for aluminum and steel can 

manufacture, dies, and wire rod hot rolls; and other products, 

such as anvils, balls, bars, bits, blades, boring tools, circuit 

board drills and other micro tools, compacts, decommissioned 

ammunition (piercers), grinding tools, high-pressure tools for 

manufacturing synthetic diamonds, honing tools, jet nozzles, 

knives, punches, mining bits, oil well drilling heads, rods, 

saw tips, seal rings and bearings, shanks, taps, wear-resistant 

parts, and woodworking cutters. Examples of used tungsten 

metal and tungsten alloy parts include decommissioned 

ammunition (piercers), electrical contacts, heating elements, 

protective shields, sputtering targets, switches, tips of sinter 

rods, and wires and filaments. Old superalloy scrap includes 

used turbine blades and other parts removed from jet engines. 

Tool steel components include blanking dies, boring tools, 

broaches, cutoff tools, drills, form tools, lathe and planer 

tools, milling cutters, punches, reamers, saw blades, and 

taps. Tungsten-bearing catalysts are used in the production 

of chemicals and petroleum and for cleaning power plant 

stack gases. Ideally catalysts are regenerated and reused, but 

eventually they are no longer effective and are considered 

spent (Kieffer and Lassner, 1987, p. 60; Froböse, 1995, p. 
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R9

280; International Tungsten Industry Association, 1997, p. 

16–19, 27–31; Carbide Recycling Co., undated; ELG Metals, 

Inc., undated; Martin Alloys Corp., undated a, b; Metal 

World, undated a-d; Recycler’s World, undated).

To estimate the amount of tungsten that becomes 

available from old scrap (termed “old scrap generated”) in 

2000, the following approach was used: For each tungstenconsuming industry in the United States, the average number 

of years the products would be in use was estimated. These 

product lifetimes were subtracted from 2000 to determine the 

year in which the product would have been manufactured. 

The amount of tungsten in the products was based on the 

amount of tungsten consumed by that industry sector during 

the year of manufacture minus the amount of tungsten that 

ended up as waste materials or new scrap. The amount of 

tungsten consumed by each industry sector in the year the 

products were manufactured was based on information 

collected by the USBM or the USGS. For some industry 

sectors, the percentage of tungsten consumed that ended up 

in final products was derived from information in a study by 

the National Research Council (1983).

This method of estimating old scrap generated is based 

entirely on tungsten consumed to make products in the United 

States and does not take into account the amount of tungsten 

in products imported into the country or exported out of the 

country. Although the net trade of tungsten in products could 

significantly alter the estimation of old scrap generated, 

the amount of tungsten in imported and exported products 

would be very difficult to quantify. Because of the lack of 

adequate information from which to make reliable estimates, 

no attempt was made to estimate the net trade of tungsten in 

products for this study.

As shown in figure 1 and table 1, 7,300 metric tons (t) of 

tungsten was contained in products that theoretically became 

available for recycling in 2000.

NEW SCRAP

New scrap is generated during the processing of tungsten 

concentrates, tungsten scrap, and tungsten chemicals to 

make tungsten metal powder, tungsten carbide powder, or 

tungsten chemicals, and during the fabrication of tungsten 

products from these materials. For the purpose of this study, 

new scrap does not include home scrap, which is generated 

and consumed within a single plant. As shown in the upper 

left part of figure 1, in 2000 an estimated 10,400 t of tungsten 

was processed to make tungsten carbide and tungsten metal 

powders in the United States. Production data for cast and 

crystalline tungsten carbide powders and tungsten compounds 

are withheld to avoid disclosing company proprietary data. In 

tungsten processing, recovery rates are high, and metal losses 

are kept to a minimum by recycling the home scrap generated. 

Losses from the domestic production of tungsten metal powder, 

tungsten carbide powder, and tungsten chemicals have been 

estimated to equal approximately 6 percent of the tungsten in 

raw materials consumed (Smith, 1994, p. 4, 7, 18–19).

Tungsten in losses, new scrap generated, and products 

from U.S. industry sectors that produced alloys, parts, and 

other tungsten-bearing products are shown on the righthand side of figure 1. Using material flows for individual 

industry sectors (National Research Council, 1983), the 

amount of tungsten lost during fabrication was estimated 

to be approximately 3 percent of the apparent supply, or 

approximately 500 t. The amount of tungsten generated as 

new scrap in 2000 was calculated from the estimated amount 

of tungsten consumed in new scrap minus imports of new 

scrap and releases of new scrap from stocks.

New scrap can be classified as either “hard” or 

“soft” scrap. Hard scrap consists of solid pieces, such as 

subspecification alloy parts, cemented carbide parts, and 

excess alloy generated during casting operations or removed 

during pressing and forging operations. Soft scrap consists 

of fine particles, such as baghouse dust from steel and alloy 

manufacturing, cutting or grinding sludges, loose powders 

generated during powder metallurgical processing, swarf, 

and turnings generated during machining of steel and alloy 

parts.

When used to produce near-net-shape parts, powder 

metallurgical processes generate less scrap than processes 

that require significant machining to produce finished parts. 

Powder metallurgical processes are used to make cemented 

carbide parts; heavy metal alloy components; mill products, 

such as lamp filaments and other tungsten metal parts; and 

some tool steels and superalloys.

Descriptions of the types of new scrap generated during 

the production of various tungsten end-use products follow. 

New cemented carbide scrap includes rejected finished 

products; tailings from pressing, presintering or sintering 

processes; and grinding residues, sludges, or powders that 

result from processing blanks or slugs (Froböse, 1995, p. 

280).

Heavy metal alloys are alloys that contain high levels of 

tungsten with copper, iron, and (or) nickel. Although heavy 

metal alloy components are produced by powder metallurgical 

processes, large quantities of scrap are generated because of 

the milling and grinding steps necessary to produce parts 

with required dimensions. Most of the new scrap is in the 

form of high-quality turnings, but powders, floor sweeps, and 

solid scrap (rejected parts) are also generated (Kieffer, 1982; 

Asher and others, 1995).

Companies that manufacture mill products from tungsten 

metal powder generate hard and soft scrap. The hard scrap is 

in the form of sinter bar ends, rod and wire end trim, and 

rejected parts. The soft scrap includes sludge from cutoff 

wheels and floor sweeps (Kieffer and Baroch, 1981, p. 18).

Alloy industries that produce parts by cast or wrought 

processes typically generate large quantities of new scrap. 

The superalloy industry is one example. The buy-to-fly ratio, 
R10 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

which is the weight of metal purchased versus the weight 

of the finished parts, provides a measure of the amount of 

scrap generated in the production of aircraft engine parts. 

Depending on the part being made, these ratios can range 

from less than 5:1 to more than 20:1. In 1998, the average 

buy-to-fly ratio was about 7:1. This means that for every 

kilogram of aircraft engine parts produced, 7 kg of metal was 

purchased, and 6 kg of scrap was generated. New superalloy 

scrap can be in the form of grindings, solids, or turnings; by 

volume, turnings are the largest quantity generated (Lane, 

1998; Schenk, 1998).

New scrap is also generated during the casting of 

corrosion-resistant alloys. In this industry sector, for every 

kilogram of alloy poured, only 0.4 to 0.6 kg of usable casting 

is produced. In other words, 40 to 60 percent of the melt 

becomes new scrap, which would be either recycled in-house 

or sold to be recycled elsewhere. The number of buyers of 

this tungsten-bearing scrap may be limited, however, by 

permissible levels of tungsten in the alloys a given melter 

produces (Spence and Stickle, 2002).

SCRAP IMPORTS

U.S. trade statistics are classified under the Harmonized 

Tariff Schedule of the United States Annotated (HTSA). The 

HTSA provides statistical categories and the applicable tariff 

rates for all merchandise imported into the United States. It 

is based on the international Harmonized System, which is 

the global classification system that is used to describe most 

world trade in goods.

The U.S. Census Bureau reported gross weight, tungsten 

content, and customs value of imports of tungsten waste 

and scrap under HTSA category 8101.91.1000, “Tungsten, 

waste and scrap.” In 2000, the United States imported 993 t 

of tungsten in tungsten-bearing scrap valued at $6.2 million 

under this category. On the basis of tungsten content, seven 

countries supplied 81 percent of these imports—China, 25 

percent; the Republic of Korea and Russia, 15 percent each; 

Germany, 8 percent; and Japan, South Africa, and Uzbekistan, 

6 percent each; the remainder was imported from 14 other 

countries (Shedd, 2002, p. 81.16–81.17).

Additional tungsten was likely to have been imported 

in scrap listed under other HTSA categories. One example 

would be cemented carbide scrap imported under HTSA 

category 8113.00.0000, “Cermets and articles thereof, 

including waste and scrap.” In 2000, the portion of imports 

under this category that was estimated to be scrap was 

determined as follows: Gross weight and dollar value statistics 

were available on a country-by-country and month-by-month 

basis. In mid-2000, the price of cemented carbide scrap was 

reported to be approximately $4.00 to $5.50 per kilogram of 

contained tungsten ($2.00 to $2.50 per pound of contained 

tungsten), which was 20 to 30 percent less than scrap prices 

1 year earlier (Metal Bulletin, 2000). The maximum amount 

of tungsten carbide in cemented carbides is 97 percent, which 

would equate to a maximum tungsten content of 91 percent 

(Sandvik Hard Materials, undated). A maximum unit value 

of $6.50 per kilogram, gross weight, was calculated using 

a maximum scrap price of $7.15 per kilogram of contained 

tungsten ($5.50 × 130 percent) and a maximum tungsten 

content of 91 percent. Imports with a unit value equal to or 

less than $6.50 per kilogram were assumed to be scrap, and 

imports with a unit value greater than $6.50 per kilogram 

were assumed to be cermets and articles thereof. An average 

tungsten content of 80 percent was assumed, which results 

in estimated imports of 2,100 t of tungsten in scrap valued at 

$10.8 million under this category. On the basis of estimated 

tungsten content, four countries supplied 99 percent of 

these imports—Canada, 49 percent; the United Kingdom, 

36 percent; Japan, 9 percent; and Germany, 5 percent; the 

remainder was imported from five other countries. By adding 

the scrap imported under these two HTSA categories, the total 

tungsten content of imported scrap in 2000 was estimated to 

be 3,100 t. Specific information on the type of scrap imported 

under each category was not available. For the purposes of 

this study, scrap imports were estimated to be approximately 

25 percent new scrap and 75 percent old scrap.

DISPOSITION OF TUNGSTEN SCRAP

Tungsten-bearing scrap can be consumed (by recycling 

or processing to recover the tungsten), discarded, dissipated, 

exported, or stocked. The influence of tungsten on living 

organisms depends on the type of organism, the type of 

tungsten compound, and the level of exposure. In general, 

tungsten and its compounds are less toxic than most other 

metals and their compounds and are considered to be 

relatively harmless to the environment. Thus, tungsten 

recycling is driven mainly by economic factors, although 

environmental factors are a consideration, as discussed in 

more detail in the “Outlook” section (International Tungsten 

Industry Association, 1997, p. 10; Lassner and Schubert, 

1999, p. 377–378, 409–416).

SCRAP CONSUMPTION (RECYCLING AND 

RECOVERY)

Estimates of new and old scrap consumption were made 

using information from various sources, which included 

data reported to the USGS, import statistics, personal 

communications with industry representatives, and published 

reports. In 2000, U.S. industry consumed an estimated 1,600 

t of tungsten in new scrap and 6,200 t of tungsten in old scrap. 

This resulted in a new-to-old-scrap ratio of 20:80 (table 1).

SCRAP EXPORTS

The Census Bureau reported the gross weight and freealongside-ship (f.a.s.) value of exports of unwrought tungsten 
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R11

and waste and scrap under HTSA category 8101.91.0000. 

An estimated 40 percent of these exports was assumed to be 

waste and scrap based on export statistics for 2002 and 2003 

in which tungsten waste and scrap was reported separately 

from unwrought tungsten. The tungsten content of this 

scrap, which was assumed to be alloy scrap, was estimated 

as follows: An average unit value of approximately $11.00 

per kilogram of contained tungsten was assumed based on 

reported prices of $9.00 to $11.00 per kilogram of contained 

tungsten ($4.00 to $5.00 per pound of contained tungsten) 

for air-melt scrap and $11.00 to $13.00 per kilogram of 

contained tungsten ($5.00 to $6.00 per pound of contained 

tungsten) for vacuum-grade scrap (Metal Bulletin, 2000). 

The estimated f.a.s. value, in dollars, of the scrap exported 

in 2000 was divided by the average unit value, in dollars per 

kilogram of contained tungsten, to estimate the kilograms 

of tungsten in the scrap. This resulted in an estimated 160 

t of contained tungsten valued at $1.7 million under HTSA 

category 8101.91.0000. Additional tungsten-bearing 

scrap was likely to have been exported under other HTSA 

categories, but information was not adequate to make reliable 

estimates of the quantities. For example, on a month-bymonth and country-by-country basis in 2000, most materials 

exported under the HTSA category called “Cermets and 

articles thereof, including waste and scrap” were assumed to 

be cermets because they had unit values that were too high 

for waste and scrap. For the purposes of this study, all scrap 

exports were assumed to be principally old scrap.

UNRECOVERED OLD SCRAP

Unrecovered old scrap represents tungsten in scrap 

that has not been recycled either in the United States or 

elsewhere. Examples of discarded tungsten-bearing products 

include burned-out lamps and lighting fixtures, electrical 

contact disks, landfilled spent catalysts and low-grade 

grinding swarfs, noncollectable carbide parts, tungsten 

carbide hardfacing materials, and welding electrode stubs. 

Generally, these materials are discarded because there is no 

efficient collection system to gather them or because they are 

not economic to recycle owing to contamination (Lassner 

and Schubert, 1999, p. 379; Oakes, 1999). An estimate of the 

amount of tungsten in unrecovered old scrap was derived by 

subtracting old scrap consumption and old scrap exports from 

old scrap supply. The magnitude of estimated unrecovered 

old scrap in figure 1 and table 1 appears to be reasonable 

considering that an estimated 35 percent of cemented carbide 

scrap is not recycled (Stjernberg and Johnson, 1998). If 5,700 

t of tungsten was generated as old cemented carbide scrap 

in 2000, then approximately 2,000 t was not recycled. The 

following factors influence the accuracy of the estimated 

unrecovered old scrap: inaccuracies in the estimate of old 

scrap generated, either from products that were still being 

used or that had been exported or from imported products that 

were not taken into account; any double counting between 

old scrap generated and old scrap imports that results from 

imported obsolete products that had been manufactured in 

the United States; and any inaccuracies in the estimates of 

old scrap consumed, stocked, or traded.

DISSIPATION

For the purpose of this study, all uses of tungsten in 

chemical applications, except for catalysts, were considered 

to be dissipative. Other sources of dissipated tungsten 

include material losses from wear during use of cemented 

carbide parts and hardfaced products, arc erosion of electrical 

contacts and electrodes, and the oxidation of alloys under 

high-temperature conditions (Smith, 1994, p. 7). A total 

of 300 t of tungsten was estimated to be the loss through 

dissipation from these industry sectors, as is indicated in the 

right-hand part of figure 1.

OLD SCRAP RECYCLING EFFICIENCY

Recycling efficiency shows the relation between the 

amount of tungsten in used products theoretically available 

for recycling and the amount that is recovered or recycled. By 

definition, this relation is the amount of tungsten in old scrap 

consumed and exported divided by the amount of tungsten 

in old scrap generated, imported, and released from stocks. 

The recycling efficiency for old scrap calculated for 2000 

was 66 percent (table 1). The accuracy of this estimate is 

dependent on the accuracy of the individual estimates used 

in its calculation.

INFRASTRUCTURE OF TUNGSTEN SCRAP 

INDUSTRY

Although the United States is a major tungsten consumer, 

tungsten mine production has not been recorded since 1992. 

In 2000, approximately 10 companies in the United States 

processed tungsten concentrates, tungsten scrap, APT, 

and (or) tungsten oxide to make tungsten metal powders, 

tungsten carbide powders, and (or) tungsten chemicals. An 

undetermined number of additional companies recycled 

cemented carbide scrap using direct methods to break down 

the scrap into powders to make new cemented carbides or 

for use as hardfacing or abrasives. U.S. tungsten supply 

comprised imports, releases from industry stocks, sales 

of excess tungsten materials from the National Defense 

Stockpile, and the recycling of tungsten-bearing scrap.

The collection and processing of tungsten-bearing scrap 

depended on several factors, such as the quality, type, and 

volume of the scrap. A wide variety of collecting, sorting, 

preliminary processing, and recycling or metal reclamation 

systems was used. Some scrap was handled by brokers, 

dealers, or waste management companies. Certain companies 
R12 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

specialized in trading and (or) processing refractory metal 

scrap, which included tungsten carbide, tungsten metal, tool 

steel, and tungsten alloy scrap.

Scrap metal processors first hand sorted solid pieces of 

new and old metal and alloy scrap by alloy type. Skilled sorters 

did a preliminary sort on the basis of color, shape (object 

recognition), and weight of the scrap items. If necessary, 

the items were then tested with one or more of the following 

methods: analysis of the spark pattern generated when the 

alloy was ground on an abrasive wheel, chemical or physical 

analysis by various methods, or response to a magnet (Newell 

and others, 1982, p. 1–2; Riley, 1990, p. 576–577). Once 

the solids were sorted by alloy type, any attachments were 

removed and all assemblies were dismantled. Additional 

processing, such as chemical milling, cutting to size, 

degreasing, pickling, shot blasting, and washing, depended 

on the condition of the scrap and the customer’s requirements 

(Meschter, 1990; Monico Alloys, Inc., undated).

Following collection, sorting, and preliminary 

processing, most of the tungsten-bearing scrap was processed 

and (or) consumed in the United States. Examples of scrap 

processing methods used in the United States are described 

in the section “Processing of Tungsten Scrap.” The remaining 

tungsten-bearing scrap was exported to foreign smelters, 

refiners, processors, or consumers either directly or following 

some initial processing.

ALLOY SCRAP

This category includes new and old scrap of the 

following types: corrosion- and wear-resistant alloys, heavy 

metal alloys, specialty steels, superalloys, and other tungstenbearing alloys. Scrap metal processors collected, sorted, 

and processed metal and alloy scrap and then returned it to 

scrap consumers for melting, recycling, or metal reclamation 

(Institute of Scrap Recycling Industries, Inc., 1996, p. 15).

Turbine engine parts from dismantled military aircraft 

are an example of tungsten-bearing old scrap. The Defense 

Reutilization and Marketing Service (DRMS) was the U.S. 

Department of Defense (DOD) agency that disposed of excess 

property received from the military services. The DRMS first 

offered excess military property for reuse within the DOD, 

transferred it to other Federal agencies, or donated it to State 

and local governments and certain nonprofit organizations. 

Property that was not reused, transferred, or donated was 

offered for sale to private companies and individuals 

(Defense Reutilization and Marketing Service, undated). The 

DRMS periodically held sealed bid sales with offers of hightemperature alloy scrap in the form of turbine engine parts. 

Scrap metal processors were potential buyers of this scrap.

CEMENTED CARBIDE SCRAP

In many cases, cemented carbide producers supplied 

scrap directly to converters, who returned recycled powders 

to them for reuse. An increasing number of cemented carbide 

producers processed their home and purchased hard scrap 

using the zinc process, as described in the section “Processing 

of Tungsten Scrap—Cemented Carbide Scrap.” Machine 

shops and manufacturers that use cemented carbide products 

collected their used inserts and other parts and sold them to 

dealers, scrap processors, or tungsten converters. The scrap 

processor’s role was to sort, clean, and repackage the scrap 

for sale (Kieffer and Lassner, 1987; Payne, 2002, p. 7–8).

MILL PRODUCTS FROM METAL POWDER SCRAP

Refractory metals companies, such as Hi-Temp Specialty 

Metals, Inc. of Willingboro, N.J., processed such solid pieces 

of pure tungsten metal as bars, cuttings, and wire spool ends. 

These were analyzed, sorted, crushed, cleaned with acid, 

and then sold as a source of tungsten to manufacturers of 

air- and vacuum-melt alloys (Queneau, 2003, p. 37; Hi-Temp 

Specialty Metals, Inc., undated a, b).

PROCESSING OF TUNGSTEN SCRAP

In 2000, a wide variety of methods was used to process 

tungsten-bearing scrap in the United States. Lassner and 

Schubert (1999, p. 380–385) classified tungsten recycling 

methods into the following four groups: hydrometallurgy, 

melting metallurgy, direct recycling, and semidirect recycling. 

In hydrometallurgical recycling, chemical methods were used 

to reclaim tungsten from scrap; this reclaimed tungsten was 

used as a substitute for tungsten ore concentrates at conversion 

plants. This processing route, which is discussed in the 

section “Tungsten Production Processes,” resulted in tungsten 

materials that were indistinguishable from those produced 

from ore concentrates. In melting metallurgical recycling, 

scrap was used as a source of tungsten in the production 

of alloys, such as steels, stellites, or superalloys; cast or 

menstruum tungsten carbide; or ferrotungsten or tungsten 

melting base. In direct recycling, the scrap was disaggregated 

into a powder by chemical and (or) physical means without 

changing its original composition. In semidirect recycling, 

one component of the scrap was dissolved chemically, which 

allowed the scrap to be broken down by physical means.

Additional information on the advantages and 

disadvantages of the many recycling methods is available 

from Kieffer (1982), Kieffer and Lassner (1987, 1994), 

Gries (1999, p. 1–5), Lassner and Schubert (1999, p. 380–

385), and Oakes (1999). In general, the chemical processes 

had advantages, such as the ability to treat all scrap types 

and remove impurities, but tended to have higher costs, 

higher reagent and energy consumption, lower yields, and 

more waste products than the direct recycling methods. 

A balance between using chemical recycling and direct 

recycling processes allowed the tungsten industry to recycle 

soft and hard, contaminated and clean scrap; to reduce the 
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R13

overall impurity levels in reclaimed materials; and to reduce 

recycling costs. The following discussion provides examples 

of the many methods used to process various types of 

tungsten-bearing scrap.

CEMENTED CARBIDE SCRAP

One of the simplest methods for recycling used cemented 

carbide inserts was to regrind them into new shapes. For 

economic reasons, this was more commonly done in Asia 

than in Western countries, and only a small percentage of all 

scrapped inserts was treated this way. In the United States, an 

estimated 35 percent of cemented carbide scrap was recycled 

using chemical processes, 25 percent was recycled using the 

zinc process, 5 percent was recycled using other processes, and 

the remaining 35 percent was not recycled. The use of the zinc 

process to recycle hard cemented carbide scrap was increasing 

(Stjernberg and Johnson, 1998; Payne, 2002, p. 7–8).

A variety of chemical methods was available to treat 

cemented carbide scrap. The most common method involved 

oxidation followed by alkali leaching. Osram Sylvania Inc. 

was an example of a U.S. company that used this type of 

chemical process. Tungsten production at Osram’s Towanda, 

Pa., conversion plant was from ore concentrates and tungstenbearing scrap. The concentrates and oxidized scrap were 

leached with sodium hydroxide to produce a sodium tungstate 

solution, which was filtered to remove byproduct sludge that 

contained cobalt and other metals recovered from the scrap. 

The sodium tungstate solution was then purified and subjected 

to a liquid ion exchange process to separate the tungsten as 

an ammonium tungstate solution from which other tungsten 

products could be produced. Two other chemical methods 

used to treat cemented carbide scrap were chlorination by the 

Axel Johnson process and fusion at high temperature with 

sodium nitrite or sodium nitrate as an oxidizing agent and 

sodium carbonate as a diluent (Kieffer, 1982; Kieffer and 

Lassner, 1987, 1994; Stjernberg and Johnson, 1998; Gries, 

1999, p. 4–5; Lassner and Schubert, 1999, p. 184–193, 381–

384; GTE Products Corp., undated, p. 8–9).

In 1998, OMG Americas expanded its Apex 

hydrometallurgical plant in Saint George, Utah, to recycle 

hard and soft cemented carbide scrap. The plant used a 

chemical process to recover APT and cobalt compounds from 

the scrap (Magdics, 1998, p. 19, 22, 26, 31; OM Group, Inc., 

2000, p. 3).

When treated by direct recycling methods, the powders 

from disaggregated cemented carbides contained tungsten 

carbide, cobalt, and any other carbides present in the original 

scrap. Coarser powders could be used as grit in hardfacing 

welding rods or to make abrasive discs, sheets, or saws and 

other tools edged with carbide grit. Finer powders were more 

or less ready to be used to make new cemented carbide parts. 

The zinc process was considered to be the most important 

direct process for recycling cemented carbide scrap. The scrap 

was first carefully sorted by grade, cleaned to remove any 

brazing or impurities, crushed, and then immersed in molten 

zinc in the presence of argon gas. The molten zinc reacted 

with the cobalt binder, which caused the scrap to expand. The 

zinc was removed by vacuum distillation, which left a porous 

material that contained the tungsten carbide, cobalt, and any 

other carbides behind. This was crushed, milled, screened, and 

blended. Following chemical analysis and carbon adjustment, 

the reclaimed powder was then ready to press into new 

cemented carbide parts. Other examples of direct recycling 

processes included “bloating/crushing” in which the cemented 

carbide was embrittled by heating it to about 1,800°C followed 

by rapid quenching and the coldstream process, in which 

blasts of air were used to accelerate scrap towards a target with 

sufficient energy to cause fracture (Kieffer, 1982; Brookes, 

1996, p. 73–74, 184–185; International Tungsten Industry 

Association, 1997, p. 10; Stjernberg and Johnson, 1998; 

Lassner and Schubert, 1999, p. 382–384).

Cemented carbide scrap could be recycled by semidirect 

methods, such as acid leaching, bloating followed by leaching, 

electrolysis, or leach milling. It could be recycled by melting 

to produce tungsten melting base, menstruum tungsten 

carbide, or specialty alloys, such as stellites (Kieffer, 1982; 

Kieffer and Lassner, 1987; Stjernberg and Johnson, 1998).

HEAVY METAL ALLOY SCRAP

The oxidation-reduction process was the preferred 

method for recycling tungsten heavy metal alloy turnings 

and powders. In this direct recycling process, the scrap was 

oxidized by heating it in air to a temperature of about 800°C, 

milled and screened, hydrogen reduced at a temperature of 

900°C to 1,000°C, screened and blended, and then mixed 

with virgin heavy metal alloy powder to make a ready-topress powder for the production of new products (Kieffer, 

1982; Kieffer and Lassner, 1994; Lassner and Schubert, 

1999, p. 381–384; Oakes, 1999).

Other methods for recycling hard or soft heavy 

metal alloy scrap included the following: the coldstream 

process for turnings and solids with binder contents of less 

than 3 percent; the menstruum process, which produced 

macrocrystalline tungsten carbide by dissolving sintered 

scrap in a carbon-saturated iron melt and then leaching the 

nickel, iron, and (or) copper with acid; melting, in which 

the scrap was used as a source of tungsten in the production 

of ferrotungsten, tool steels, or tungsten melting base; and 

chemical processing. Electrolysis, which uses the scrap as an 

anode in an electrolytic solution, could be used to dissolve the 

tungsten from hard heavy metal alloy scrap prior to chemical 

processing. Leach milling and leaching with an iron chloride 

solution to dissolve copper, nickel, and iron selectively were 

other possible methods for recycling heavy metal alloy scrap 

(Kieffer, 1982; Kieffer and Lassner, 1987, 1994; Lassner and 

Schubert, 1999, p. 193–194, 377, 380–384; Oakes, 1999).
R14 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

In the process used by Metek Metal Techology, Ltd. in 

Ramat Hovav, Israel, tungsten-bearing scrap was mixed with 

sodium nitrate and sodium nitrite and fed into a preheated 

revolving furnace. The chemicals and scrap reacted 

exothermically to form soluble sodium tungstate; insoluble 

hydroxides of cobalt, iron, and nickel; and insoluble sodium 

tantalate and sodium titanate. As soon as the molten charge 

from the furnace was poured into water, the sodium tungstate 

dissolved. The resulting solution was filtered, the pH was 

increased, and calcium chloride was added to precipitate 

insoluble calcium tungstate. The calcium tungstate was 

suspended in water, and hydrochloric acid was added to 

produce insoluble tungstic acid, which could be treated by 

conventional methods to produce tungsten oxide, tungsten 

metal powder, or tungsten carbide powder (Asher and others, 

1995).

MILL PRODUCTS FROM METAL POWDER SCRAP

The preferred use for hard pure tungsten scrap, in 

terms of economic value, was as a source of tungsten in the 

manufacture of superalloys. The scrap was analyzed, sorted, 

crushed, and then cleaned with acid before being sold to 

producers of air- or vacuum-melted alloys. The preferred use 

for pure tungsten scrap powder was as a source of tungsten 

in the production of cast or menstruum tungsten carbide. 

In addition, pure tungsten metal scrap could be recycled 

using the following methods: chemical processing; melting, 

in which the scrap was used as a source of tungsten in the 

production of ferrotungsten, stellites, tool steels, or tungsten 

melting base; oxidation-reduction; and the coldstream 

process. Electrolysis, which uses the scrap as an anode in an 

electrolytic solution, could be used to dissolve the tungsten 

prior to chemical processing (Kieffer, 1982; Kieffer and 

Lassner, 1987; Lassner and Schubert, 1999, p. 193–194, 377, 

381; Queneau, 2003, p. 37; Hi-Temp Specialty Metals, Inc., 

undated a, b).

RESIDUES

Tungsten-bearing sludges, which often contained 

aluminum oxide or silicon carbide impurities, were generated 

during grinding of tungsten, tungsten alloy, and tungsten 

carbide products. Depending on their chemistry, these 

grinding residues were recycled by chemical methods or 

by melting to produce ferrotungsten, menstruum tungsten 

carbide, tool steels, or tungsten melting base (Kieffer, 1982; 

Kieffer and Lassner, 1987).

SPENT CATALYSTS

Processes for recovering metals from spent cobaltbearing catalysts were well established (Shedd, 2003a, p. 

M11–M12). Although various metal recovery processes had 

been developed for spent nickel-tungsten hydrocracking 

catalysts, most of this scrap was sent to nickel smelters or 

landfills. Some U.S. metal recovery facilities could not 

accept spent tungsten-bearing catalysts because they needed 

to avoid contaminating their molybdenum and vanadium 

products with tungsten. In addition, low tungsten prices can 

make recycling of spent catalysts uneconomical (Kieffer and 

Lassner, 1987; Berrebi and others, 1992; Case and others, 

1995, p. 465; Llanos and Deering, 1995, p. 427; Sackett, 

2003, p. 16; Eurecat S.A., undated).

STEEL AND SPECIALTY ALLOY SCRAP

Significant amounts of tungsten-bearing steel scrap were 

recycled by melting during steel production. Typical melts 

contained more than 60 to 70 percent scrap, which included 

home scrap (Kieffer, 1982).

Specialty alloy scrap included such alloys as stellites 

and superalloys. Turnings represented the largest quantity, 

by volume, of superalloy scrap generated. Scrap processors 

collected these turnings; qualitatively verified their chemical 

purity to remove materials that would contaminate a superalloy 

melt; crushed the turnings into chips; quantitatively assayed 

the chips; cleaned residual cutting fluids and dirt from the 

chips by kiln processing, detergent cleaning, or solvent 

cleaning; sampled and analyzed the scrap to certify that it met 

certain chemical specifications; prepared homogeneous lots 

if desired; densified the chips if desired; and then packaged 

the scrap for return to superalloy melters (Lane, 1998).

THORIATED TUNGSTEN SCRAP

Tungsten electrodes that contained about 2 percent 

thorium oxide were the most common type of electrode used 

for gas tungsten arc welding (also called tungsten inert gas 

welding) of carbon and stainless steels. Thoriated tungsten 

electrodes were also used in a variety of high-performance and 

special application lighting products, such as high-intensity 

discharge lamps. Because thorium is radioactive, thoriated 

tungsten scrap posed special environmental challenges when 

recycled (International Tungsten Industry Association, 1997, 

p. 27; Oakes, 1999; National Radiological Protection Board 

and Gesellschaft für Anlagen- und Reaktorsicherheit mbH, 

2001, p. 9, 12; Smith, 2001).

In the mid-1990s, an estimated 80 t/yr of thoriated 

tungsten was produced in the United States. The powder input 

to make thoriated tungsten products was approximately 80 

percent virgin material, 18 percent new scrap, and 2 percent 

old scrap. Of the raw materials used to produce thoriated 

tungsten products, 64 percent ended up in the final products, 

and 36 percent became scrap. Roughly one-half of this new 

scrap was impure, and one-half was clean. Impure thoriated 

tungsten scrap was processed by the following method: the 

scrap was oxidized in air and then either reduced with iron 

using a silicothermic or aluminothermic process to make 

ferrotungsten, tool steel, or tungsten melting base, or the scrap 
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R15

was processed chemically to make APT. The thorium oxide, 

which ended up in the slag in the production of ferrotungsten 

or in the filter cake in the production of APT, was sent to 

a low-level radiation depository. Clean thoriated tungsten 

powders, solids, and turnings, which were generated as new 

scrap during the production of thoriated tungsten products 

or, in the case of solids, as old scrap by consumers, were 

processed using the oxidation-reduction method. The scrap 

was recrystallized, crushed, subjected to magnetic separation 

to remove iron-contaminated scrap, oxidized in air, hydrogen 

reduced, screened, blended, assayed, and then mixed with 

virgin thoriated tungsten to make a ready-to-press powder for 

the production of new products. The iron-contaminated scrap 

was then processed as impure scrap (Kieffer and Lassner, 

1994; Lassner and Schubert, 1999, p. 377, 381–382).

OUTLOOK

The recycling of tungsten-bearing scrap and the 

recovery of tungsten from scrap materials are wellestablished practices for a number of reasons. The value 

of the tungsten and other metals present in the scrap, such 

as cobalt, columbium (niobium), copper, nickel, rhenium, 

silver, titanium, and tantalum, provides economic reasons to 

recycle. The use of scrap helps to improve process yields and 

to diversify the sources of raw materials for the production of 

tungsten chemicals, tungsten metal powders, and tungstenbearing end products. This helps to reduce potential supply 

disruptions that could result from a high dependence on 

imports and to reduce price volatility. Other important factors 

that play a role in promoting tungsten recycling and recovery 

include environmental considerations (including regulations) 

and the desire to conserve resources and energy, to reduce 

environmental damage from mining, to reduce mining and 

processing wastes and the costs of disposing wastes and 

used products, and to portray an environmentally responsible 

image (Kieffer and Lassner, 1987, 1994; Stjernberg and 

Johnson, 1998; Oakes, 1999).

Increases in recycling since the mid-1970s have been 

attributed to the following factors: increased use of indexable 

inserts, which are easier to recycle than brazed tools; an 

increased appreciation of the value of tungsten through better 

communication and education; a better understanding of the 

value of other metals present in the scrap; improved scrap 

collection and separation at the places where it is generated; 

improved recycling methods; a steadily growing environmental 

awareness; and stricter regulations in industrialized countries. 

The primary reasons cited for discarding scrap rather than 

recycling it were the lack of efficient collection systems for 

certain scrap types and contamination, which makes some 

scrap recycling uneconomical. To a lesser extent, metal 

prices influence tungsten recycling. Higher metal prices and 

continued education of consumers on the value of their scrap 

could result in improved sorting of scrap in the places where 

it is generated, improved collection systems, and higher 

recycling efficiencies. An increase in the share of recycling 

by direct methods was expected even though it would require 

consuming industries to learn how to modify production 

conditions to accommodate reclaimed materials (Kieffer and 

Lassner, 1994; Smith, 1994, p. 22; Lassner and Schubert, 

1999, p. 384–385; Oakes, 1999).

World tungsten consumption is expected to continue to 

increase in the coming years. Because most tungsten products 

can be recycled, the availability of tungsten-bearing scrap also 

is expected to increase. The rate of increase may be dampened 

somewhat by improvements in products, such as coatings 

on cemented carbide parts, that increase their useful life. In 

addition to the types of scrap discussed in this report, a new 

source of tungsten-bearing scrap was expected to become 

available as the U.S. Army’s “green bullet” program moved 

to full-scale production. Recycling used bullets from firing 

ranges was an integral part of the program, and large quantities 

of scrap were expected to be generated as the Army moved 

towards 100-percent replacement of lead in ammunition 

(Oakes, 1999; Middleton, 2000, p. 5, 7, 14, 20–22).

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APPENDIX—DEFINITIONS

apparent consumption. Primary plus secondary production 

(old scrap) plus imports minus exports plus adjustments 

for Government and industry stock changes.

apparent supply. Apparent consumption plus consumption 

of new scrap.

cast tungsten carbide. Tungsten carbide produced by 

melting tungsten and carbon in a vacuum arc furnace. 

The resulting carbide has a martensitic structure and 

eutectic two-phase composition (W2C–WC) and is very 

hard and abrasion-resistant.

catalyst. A substance that changes the rate of a chemical 

reaction without being consumed in the reaction.

dissipative use. A use in which the metal is dispersed or 

scattered, such as paints, fertilizer, or pigments, making 

it exceptionally difficult and costly to recycle or recover 

the metal.

hard scrap. Scrap consisting of solid pieces. Examples of old 

hard scrap include used alloy or cemented carbide parts. 

Examples of new hard scrap include subspecification 

alloy or cemented carbide parts and excess alloy 

generated during casting operations or removed during 

pressing and forging operations. Compare with “soft 

scrap.”

home scrap. Scrap generated as process scrap and consumed 

in the same plant where it is generated.

menstruum tungsten carbide. Tungsten carbide produced 

by a menstruum process, in which macrocrystalline 

tungsten carbide grains are produced by dissolving 

sintered scrap in a carbon-saturated iron melt and then 

leaching the nickel, iron, and (or) copper with acid.

new scrap. Scrap produced during the manufacture of 

metals and articles for both intermediate and ultimate 

consumption, including all defective finished or 

semifinished articles that must be reworked. Examples 

of new scrap are borings, castings, clippings, drosses, 

sintered cemented carbide parts, skims, and turnings. 

New scrap includes scrap generated at facilities that 

consume old scrap. Included as new scrap is prompt 

industrial scrap—scrap obtained from a facility separate 

from the recycling refiner, smelter, or processor. 

Excluded from new scrap is home scrap that is generated 

as process scrap and used in the same plant.

new-to-old-scrap ratio. New scrap consumption compared 

with old scrap consumption, measured in weight 

and expressed as a percentage of new plus old scrap 

consumed (for example, 40:60).

old scrap. Scrap including (but not limited to) metal articles 

that have been discarded after serving a useful purpose. 

Typical examples of old scrap are electrical wiring, 

lead-acid batteries, silver from photographic materials, 

metals from shredded cars and appliances, used 

aluminum beverage cans, spent catalysts, and tool bits. 

This is also referred to as postconsumer scrap and may 

originate from industry or the general public. Expended 

or obsolete materials used dissipatively, such as paints 

and fertilizers, are not included.

old scrap generated. Tungsten content of products 

theoretically becoming obsolete in the United States in 

the year of consideration, excluding dissipative uses.

old scrap recycling efficiency. Amount of old scrap 

recovered and reused relative to the amount available to 

be recovered and reused. Defined as [consumption of old 

scrap (COS) plus exports of old scrap (OSE)] divided 

by [old scrap generated (OSG) plus imports of old scrap 

(OSI) plus a decrease in old scrap stocks (OSS) or minus 

an increase in old scrap stocks], measured in weight and 

expressed as a percentage:

old scrap supply. Old scrap generated plus old scrap 

imported plus old scrap stock decrease.

old scrap unrecovered. Old scrap supply minus old scrap 

consumed minus old scrap exported minus old scrap 

stock increase.

price. Prices for tungsten scrap are not published on a routine 

basis. The total value of old scrap consumed in 2000 was 

estimated using the unit values of imported tungstenbearing scrap and prices from Metal Bulletin (2000).

recycling. Reclamation of a metal in useable form from scrap 

or waste. This includes recovery as the refined metal 

or as alloys, mixtures, or compounds that are useful. 

Examples of reclamation are recovery of alloying metals 

(or other base metals) in steel, recovery of antimony in 

battery lead, recovery of copper in copper sulfate, and 

even the recovery of a metal where it is not desired but 

can be tolerated—such as tin from tinplate scrap that is 

incorporated in small quantities (and accepted) in some 

steels only because the cost of removing it from tinplate 

scrap is too high and (or) tin stripping plants are too few. 

In all cases, what is consumed is the recoverable metal 

content of scrap.

recycling rate. Fraction of the apparent metal supply that is 

scrap on an annual basis. It is defined as [consumption of 

old scrap (COS) plus consumption of new scrap (CNS)] 

divided by apparent supply (AS); measured in weight 

and expressed as a percentage:

COS + CNS

AS

×100

scrap consumption. Scrap added to the production flow of a 

metal or metal product.

soft scrap. Scrap consisting of fine particles. Examples 

include cutting or grinding sludges, swarf, turnings 

generated during machining of steel and alloy parts, 
TUNGSTEN RECYCLING IN THE UNITED STATES IN 2000 R19

baghouse dust from steel and alloy manufacturing, and 

loose powders generated from powder metallurgical 

processes (pressing, presintering, and sintering).

stellites. The word Stellite is a registered trademark of the 

Deloro Stellite Company. Stellites are a class of alloys 

containing cobalt, chromium, and tungsten, which are 

characterized by their ability to resist all types of wear, 

particularly at elevated temperatures and under corrosive 

conditions.

superalloys. Alloys developed for high-temperature service 

where relatively high mechanical stress is encountered 

and where surface stability is frequently required.

swarf. Fine metallic particles and abrasive fragments 

removed by cutting or grinding tools.