U.S. Department of the Interior

U.S. Geological Survey

Silver Recycling in the United States in 2000 

By Henry E. Hilliard 

U.S. GEOLOGICAL SURVEY CIRCULAR 1196–N

FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES

U.S. DEPARTMENT OF THE INTERIOR 

GALE A. NORTON, Secretary 

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director 

U.S. GEOLOGICAL SURVEY, RESTON, VIRGINIA : 2003 

Version 1.0 

Published online in the Eastern Region, Reston, Va., 2003. 

Manuscript approved for publication May 29, 2003. 

Any use of trade, product, or firm names in this publication is for 

descriptive purposes only and does not imply endorsement by 

the U.S. Government. 
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. 

Charles G. Groat 

Director 

III 
CONTENTS


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


Conversion Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N1


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


U.S. and World Geologic Occurrence of Silver . . . . . . . . . . . . . . . . . . . . . . . 1


Mining and Processing Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1


Sources of Silver Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Old Scrap generated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3


Photographic Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Electrical and Electronics Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Jewelry and Silversmith Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Spent Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Home Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6


Disposition of Silver Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Old Scrap Recycling Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Infrastructure of Silver Scrap Recycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6


Photographic Processing Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6


Electrical and Electronics Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6


Jewelry and Sterling ware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7


Catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7


Manufacturing Wastes and Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7


Processing of Silver Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


Photographic Wastes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


Electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Metallic Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Precipitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Electrical and Electronics Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


Jewelry and Silversmith Scrap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9


Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9


References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Appendix—Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

FIGURES 

1. 	Diagram showing U.S. silver materials flow in 2000 . . . . . . . . . . . . . . . . . . . . . . . N2 

2. 	Graph showing U.S. silver consumption, by end-use sector, from 1980 through 

2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . N5

TABLE 

1. 	Salient statistics for U.S. silver scrap in 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . N3 

2. 	U.S. silver consumption in the photographic industry . . . . . . . . . . . . . . . . . . . . . . N4 

IV 
CONTENTS V 

CONVERSION FACTORS 

Multiply By To obtain 

Mass 

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

For temperature conversions from degrees Celsius (°C) to degrees Fahrenheit (°F), use the following: 

°F = (1.8 × °C) + 32 
FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES 

Silver Recycling in the United States in 2000 

By Henry E. Hilliard 

ABSTRACT 

In 2000, the global silver supply deficit (the difference 

between mine and scrap supply and silver demand) was 

more than 3,000 metric tons. U.S. silver demand for photographic applications alone was nearly equal to annual U.S. 

silver production. Until 1968, the U.S. silver deficit was 

filled by withdrawals from the U.S. Treasury reserves. In 

2000, the deficit was filled by destocking, imports, and 

recycling. Photographic wastes, spent catalysts, and electronic scrap are the major sources of materials for silver 

recycling. Nearly 1,800 metric tons of silver contained in 

these materials were available for recycling in 2000. Other 

recyclable silver-bearing materials include dental alloys, 

jewelry, and silverware. In 2000, an estimated 1,700 tons of 

silver were recovered from secondary sources in the United 

States. The U.S. recycling efficiency for old scrap was calculated to have been 97 percent in 2000; the recycling rate 

was estimated to be 32 percent. 

INTRODUCTION 

The use of silver dates from the earliest historic 

records, and it was usually extracted by melting silver-bearing lead ore (ore containing argentiferous galena). Silver, 

which is the least expensive of the precious metals, is the 

whitest element and has the highest electrical and thermal 

conductivity of all the metals. Silver was once used primarily for coinage, decorative articles, jewelry, and silverware. 

Today, coinage has become an insignificant use and the aesthetic uses for silver have been surpassed by industrial and 

technical uses. Industrial and technical uses include brazing 

alloys, catalysts, electrical/electronics products, and photographic paper and film. Recycling1 of silver from these uses 

is an important part of its supply. 

U.S. AND WORLD GEOLOGIC OCCURRENCE OF 

SILVER 

Identified resources of silver in the United States comprise an estimated 33,000 metric tons (t) at 2000 prices and 

a reserve base of about 72,000 t (Hilliard, 2001). Only a 

small portion of these resources are silver ores that can yield 

1Definitions for select words are found in the Appendix. 

silver as the main product (primary ores); the remainder can 

be economically recovered only as a byproduct of copper, 

gold, lead, or zinc production (U.S. Geological Survey, 

2000, p. 10-12). 

There are about 55 silver minerals, which include 

argentite (Ag2S), cerargyrite (AgCl

), native silver (Ag), 

pearceite (Ag16As2Sb11), polybasite (Ag16Sb2S11), proustite 

(Ag3SbS3), stephanite (Ag5SbS4), stromeyerite (AgCaS), 

and the tellurides. These minerals are commonly associated 

with lead, but they are also associated with copper, gold, 

and zinc. Ores in which silver is the main component are 

associated with igneous rocks of intermediate felsic composition. Examples include the McCoy/Cove Mine and the 

Comstock gold-silver deposit in Virginia City, Nev., where 

almost 31,100 t was produced, and cobalt-silver ores in the 

Cobalt District of Ontario, Canada. The main silver-producing tetrahedrite vein deposits in the Coeur d'Alene district of 

Idaho occur in Precambrian quartzites and argillites. Silverbearing base-metal ores are found in copper porphyries, 

massive sufide ores, and copper-lead-zinc vein deposits 

(Heyl and others, 1973; Reese, 1985, p. 729–739). 

In 2000, Mexico was the world's leading silver-producing country with a production of 2,620 t. Peru (2,150 t) was 

second followed by Australia (2,060 t), the United States 

(1,980 t), and Chile (1,240 t). World production in 2000 was 

18,300 t (Hilliard, 2002, p. 70.11). 

MINING AND PROCESSING METHODS 

In the United States, silver ore is mined primarily by 

openpit and subsurface shafts and drifts. The method used 

varies from one ore body to another depending on the ore 

grade, the steepness of the terrain, availability of transportation, reserves, ore body or vein shapes, depth of mining, 

character of host rock, and economic factors peculiar to the 

individual mine. At the Sunshine Mine in Coeur d’Alene, 

Idaho, the tetrahedrite silver ore is extracted through one 

main vertical shaft and several winzes and developmental 

drifts along the veins. Mining is principally by the cut-andfill stoping method; explosives break the vein and host rock 

into pieces for transport by mine car and electric locomotive 

to the main shaft where the ore is hoisted to the surface. At 

the surface, the ore is subjected to crushing and fine grinding. Amalgamation, cyanidation, and leaching were first 

N1 
N2 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES 

Figure 1. U.S. silver materials flow in 2000. Values are in metric tons of silver. 
SILVER RECYCLING IN THE UNITED STATES IN 2000 N3 

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


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


Old scrap: 

Generated1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,760 

Consumed2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,680 

Consumption value . . . . . . . . . . . . . . . . . . . . . $270 million

Recycling efficiency3 . . . . . . . . . . . . . . . . . . . . . 97 percent 

Supply4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,820 

Unrecovered5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 

New scrap consumed6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 530 

New-to-old-scrap ratio7 . . . . . . . . . . . . . . . . . . . . . . . . . . . 24:76 

Recycling rate8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 percent 

U.S. net exports of scrap9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 

Value of U.S. net exports of scrap . . . . . . . . . . . . . . $4.2 million 

1Silver content of products theoretically becoming obsolete in the 

United States in 2000. Dissipative uses are excluded. 

2Silver content of products that were recycled in 2000. 

3(Old scrap consumed plus old scrap exported) divided by (old scrap 

generated plus old scrap imported minus old scrap stock increase). 

4Old scrap generated plus old scrap imported plus old scrap stock 

decrease. 

5Old scrap supply minus old scrap consumed minus old scrap exported minus old scrap stock increase. 

6Includes prompt industrial scrap but excludes home scrap. 

7Ratio of quantities consumed, in percent (See Appendix—Definitions). 

8Fraction of the metal apparent supply that is scrap on an annual basis. 

It is defined as (consumption of old scrap plus consumption of new scrap) 

divided by apparent supply (see appendix), measured in weight and 

expressed as a percentage. 

9Trade in scrap is assumed to be principally in old scrap. 

adapted to extract silver from high-grade ores. As these ores 

became less plentiful, processes for treating low-grade ores 

were developed, thus allowing amalgamation to be essentially discontinued. Improvements in the technique of 

cyanidation of low-grade gold-silver ores and the development of activated-carbon stripping of the pregnant solutions 

led to the use of cyanidation for these ores. For silver-bearing lead ores, a flotation process is used to separate the silver-bearing galena from waste rock particles (tailings) to 

form a concentrate. Ground-up ore, water, and special 

chemicals are mixed together and constantly agitated in a 

bank of flotation cells. Air is blown through the mixture in 

each cell, and fine silver-bearing galena particles adhere to 

the bubbles that rise to form a froth on the surface of the 

cell. The tailings sink to the bottom of the cell and are 

removed. The froth is skimmed off, and the resulting silverlead sulfide concentrate may assay from 0.8 to 1 kilogram 

per metric ton (kg/t) of silver (Heinen and others, 1979, p. 

1–5; Hussey and others, 1979, p.1–6). 

The concentrate produced in the flotation cell is sintered (partly melted) to combine the fine particles into 

lumps and to remove some of the sulfur as sulfur dioxide. 

It is then smelted in a blast furnace and drossed (removal of 

trace copper and impurities) to produce a crude lead metal 

that may contain as much as 2 kg/t of silver. 

Silver is recovered when lead is refined to high purity. 

Crude lead is remelted, and antimony and other impurities 

are removed. The molten lead is then poured into a large 

upright container where it plunges through a molten zinc 

metal layer that floats on top of molten lead. The container 

is increasingly cooled toward its base so that as the incoming molten lead descends, the contained silver and any contained gold and copper combine with the molten zinc 

dragged down from the zinc layer and form crystals of copper-gold-silver-and zinc alloy (called doré). The crystals 

float to the surface and redissolve in the zinc layer. The zinc 

layer is periodically skimmed off. The doré is removed for 

further smelting. The final smelter product is cast into plates 

for the electrolytic removal of copper and separation of 

high-purity silver and gold bullion. 

SOURCES OF SILVER SCRAP 

For analytical purposes, silver in circulation can be 

divided into three categories—products still in use (coins 

and medallions held for investment), items scrapped and/or 

recycled, and those irretrievably lost (figure 1; table 1). For 

example, of the 2,500 t of silver consumed in the United 

States in photographic applications in 2000, some of the 

metal is still in use (archived X-ray film, black and white 

photographs), another part has been recycled (silver recovered from fixer solutions), and some of it has been irretrievably lost (low-grade film disposed of in landfills and dilute 

solutions poured down drains) (World Silver Survey 2001, 

2001, p. 55). 

OLD SCRAP GENERATED 

Photographic Wastes 

Manufacturers of photographic materials are reluctant 

to provide accurate data about their silver consumption, how 

much silver was purchased, and how much was recycled 

from manufacturing wastes and captive film processing 

establishments. Nevertheless, the consumption of silver can 

be estimated by calculating the amount contained in the 

products used by consumers. 

The silver content of photographic materials, which is 

called the coating weight, varies from less than 1 to 8 grams 

per square meter (g/m2). Generally, slow-speed, fine-grain 

emulsions have lower coating weights than high-speed 

coarse-grain emulsions, and films usually have higher speed 

and coarser grain emulsions than photographic papers. Normally, about 50 percent of the total silver incorporated in 

emulsions is used for the formation of continuous tone 

(C.T.) images; for example, chest X-rays, pictorial scenes, 

and portraits. Images of line drawings, documents, graphs, 

and halftone images normally require about 20 percent of 

the available silver (positive image) to about 80 percent for 

negative images. The average coating weight of silver on 
N4 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES 

Table 2. U.S. silver consumption in the photographic industry 

Photographic Coating weight U.S. consumption Silver content Recoverable silver 

material (grams per (millions) (metric tons) Percentage Metric tons 

square meter) 

Films: 

Color negative 5-8 11,030 262 100 262 

Color reversal 4-6 151 11 100 11 

Black and White 5-7 140 10 40-50 4 

Motion picture 5-7 227.4 165 100 165 

Plates: 

X-ray (medical, 

industrial, dental) 4-6 2110 550 40-50 248 

Graphic arts 3-5 253.1 212 20-80 138 

Paper: 

Black & white (C.T.) 1-5 214.1 56 40-60 28 

Black & white (line) 1-5 28.645 35 20-80 21 

Color 0.7-1/2 2572 572 100 572 

Total 1,870 1,450 

1Rolls of film.


2Square meters of photographic film, paper, or plates.


paper is 2 ounces per 1,000 square feet (Eastman Kodak 

Company, 1998). 

The calculation of the amount of silver available for 

recovery based on product usage requires two sets of data— 

the amount of films and paper consumed in square meters 

and the coating weight of each product type; that is, the silver concentration per square meter. To estimate the amount 

of recoverable silver based on U.S. silver consumption in 

color negative film in 2000, the following were assumed: 

1.	 The average film mix was 70 percent with a coating 

weight of 5.4 g/m2 and 30 percent with a coating weight 

of 8.0 g/m2. 

2.	 The average roll of film was 24 exposures [0.041 

square meter (m2)]. 

In 2000, U.S. consumption of color roll film, which included disk and one-time-use cameras, was 1,030 million rolls 

(Donald Franz, Photofinishing News, oral commun., 2002). 

The average amount of silver available per roll of film was 

as follows: 

5.4 g/m2 x 70 percent = 3.8 g/m2 

8.0 g/m2 x 30 percent = 2.4 g/m2 

Total = 6.2 g/m2 

6.2 g/m2 x 0.041 m2 per roll = 0.254 gram (g) per roll. 

The amount of silver available for recovery from color 

films was as follows: 

0.254 g per roll x 1,030 million rolls x 100 percent recoverable = 262 million grams, or about 260 t. Following this 

procedure for the other types of film, paper, and other photographic materials, U.S. consumption of silver by the photographic industry in 2000 was estimated to be 1,870 t; an 

estimated 1,450 t of silver was available for recycling from 

photographic wastes. The Silver Institute estimated the 

total U.S. demand for silver in photographic applications in 

2000 to be about 2,500 t. On the basis of the above figures, 

about 630 t of silver was contained in photographic products in the pipeline for delivery to consumers, on the shelf, 

or in the cameras of consumers. An estimated 420 t of silver was retained on negatives and photographic papers and 

was irretrievably lost. 

Electrical and Electronics Scrap 

Electronics scrap can vary widely in physical aspect, 

metal content, and heterogeneity and only a weak infrastructure exists in the United States to capture electronics 

wastes. More than 20 million personal computers became 

obsolete in 2000. Most of these are in storage. Of the 

remainder, the bulk were disposed of; probably fewer than 6 

percent were recycled. In 2000, the useful life of a computer was 3 to 5 years and shrinking. More than 63 million personal computers are projected to be retired in 2005 (U.S. 

Environmental Protection Agency, 2000). 

Approximately 400 companies have been identified as 

having electronics recycling operations in the United States. 

The top 10 companies recycled approximately 65 percent of 

the total volume of available electronics scrap. The top five 

companies recycled about 43 percent. Among the top companies, 2 recycled more than 600 metric tons per year (t/yr), 

and the next 10 recycled between 300 and 600 t/yr. Most 

companies recycled less than 160 t/yr (International Association of Electronics Recyclers, 2001). 
SILVER RECYCLING IN THE UNITED STATES IN 2000 N5 

Figure 2. U.S. silver consumption, by end-use sector, from 1980 through 2000. Other industrial includes 

catalysts, electroplated wares, coins and medallions, dental and medical, and bearings. 

The scope of electronics recycling includes computer, 

telecommunications, military, and consumer electronics 

equipment. The total weight of electronics products recycling in 2000 was approximately 8,900 t. In addition, 

approximately 1,000 t of electronics parts, subassemblies, 

and materials were recycled (International Association of 

Electronics Recyclers, 2001). The silver content of computer and other electronics scrap can vary from 0.02 to 0.5 percent (Mid-Atlantic Consortium of Recycling and Economic 

Development Officials, 2000). The U.S. Geological Survey’s estimate for silver recycled from this source was 90 t 

in 2000. 

The Defense Reutilization and Marketing Service 

(DRMS) receives excess and obsolete electronics equipment from the U. S. Department of Defense (DOD). This 

property may be distributed to other parts of DOD or transferred to other Federal agencies, donated to State and local 

governments, sold by DRMS commercial venture agents, or 

demanufactured. In 2000, DRMS processed 334,500 t of 

military and other electronics scrap; 3,520 t of this material 

contained precious metals from which 334 kilograms (kg) 

of gold, 51 kg of palladium, 18 t of silver, and 9 kg of platinum were recovered (John Barrett, Demanufacturing Program Manager, Defense Reutilization and Marketing Service, oral commun., 2001). 

Jewelry and Silversmith Scrap 

The silverware industry produces liquid and solid 

scrap. Most of the liquid waste is produced by the silver 

plating segment of the industry. Solid wastes are mostly 

from the production of sterling ware. No data are available 

on the amount of each type of waste that is processed for 

recovery. 

Spent Catalysts 

Catalyst formulations are closely held proprietary technology. Silver-bearing scrap generated during the early 

stages of the catalyst production process is simply returned 

to the process. Scrap that is generated at a later stage of the 

process, such as end-of-life catalysts or a substrate that has 

already been coated with silver, is usually sent to a toll 

refiner for the recovery of silver. Catalyst manufacturers 

commonly take back spent catalysts from their customers 

and arrange for the recycling themselves. This is partly to 

protect proprietary catalyst formulations. 

A typical use of a silver-based heterogeneous catalyst 

in a chemical process is the catalytic oxidation of ethylene 

to ethylene oxide over a silver catalyst. The catalyst is 

believed to be silver on a preformed alpha-alumina carrier. 

The catalyst for each process is somewhat different, and 

each manufacturer offers its own proprietary catalyst. Exact 

compositions and methods of manufacture of the catalyst 

are closely guarded secrets as are the quantities of catalyst 

used for each process (Hull & Co., 1990, p. 109). 

The silver content of the catalysts has been estimated to 

fall in the range of 8 to 15 percent. Some ethylene oxide 

plants that use oxygen require an initial silver charge of 

about 1 kg per 1,200 kilograms per year (kg/yr) of ethylene 

oxide capacity; others are estimated to require an initial silver charge that is about 75 percent higher, or about 1 kg/700 

kg/yr of ethylene oxide capacity. Catalyst life varies considerably, particularly for air process plants, depending on the 

purity of the air and ethylene feed (traces of chlorine can 

poison the catalyst). A good estimate of the average catalyst 

life for the air process is 2 to 3 years, although some catalyst charges have lasted as long as 12 years. Ethylene oxide 
N6 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES 

plants that use an oxygen feed enjoy a longer catalyst life 

that has been estimated to be from 5 to 7 years (Hull & Co., 

1990, p. 225). U.S. ethylene oxide output in 2000 was 3.9 

million metric tons (Chemical & Engineering News, 2001). 

Assuming production at 95 percent of capacity and a 12­

percent silver content of the catalyst, total silver content of 

the U.S. catalyst inventory in 2000 was estimated to be 

about 510 t. 

HOME SCRAP 

Companies that manufacture semifinished and final 

products that contain silver and other precious metals 

reprocess virtually all scrap generated for precious-metals 

recovery. Casting scrap, such as croppings of castings, is 

recovered by simply adding it to melt charges. This material is not counted as scrap consumed because it is continuously recirculated and never leaves the plant. Grindings, 

ingot scalping, and machine chips are processed through toll 

refining. 

DISPOSITION OF SILVER SCRAP 

Silver scrap is generated primarily in the industrialized 

countries, which indicates that demand for silver is skewed 

toward industrial nations. Also, silver-bearing scrap is 

mostly from electronics and photographic sources. Jewelry 

and silverware are less important as a source of recycled 

metal. This is important because despite strong growth in 

demand in developing countries, consumption of silver in 

electronics and photography in 2000 was still biased 

towards the United States, Europe, and Japan. By contrast, 

demand for silver in jewelry was dominated by Indian and 

other Asian markets where recycling rates are traditionally 

very high. The closure of the Handy & Harman facility in 

Attleboro, Mass, in 1999 led to a substantial loss of capacity and to a temporary disruption in the scrap supply chain. 

Although other plants took up the slack, capacity constraints were still evident at times, which resulted in higher 

volumes of scrap being treated outside the United States. 

Nevertheless, the scrap supply increased in the United 

States in 2000 to 1,820 t. This was due to an increase in the 

recycling of photographic wastes, which has been growing 

for about 10 years, and an increase in the volume of spent 

catalysts; the volume of electronics scrap also seems to 

have risen. 

OLD SCRAP RECYCLING EFFICIENCY 

Recycling efficiency shows the relation between old 

scrap materials theoretically available for recycling and old 

scrap that is actually recycled. Silver-bearing scrap materials consist mostly of electrical and electronics scrap, photographic wastes, scrap jewelry, silverware, and spent catalysts. The chemical industry recycled spent silver-bearing 

catalysts with recovery rates of more than 98 percent. The 

exact figure for recycling efficiency is uncertain owing to 

lack of data on stocks of silver-bearing material, but old 

scrap recycling efficiency was estimated to be 97 percent. 

INFRASTRUCTURE OF SILVER SCRAP 

RECYCLING 

PHOTOGRAPHIC PROCESSING FACILITIES 

Silver-based photographic materials are made for many 

applications that require different photochemical and physical response characteristics and a wide variety of formats 

and sizes. All these products are laminates that consist of a 

surface-treated support and bonded emulsions. Films have 

transparent or translucent plastic supports, which are mostly cellulose triacetate and polyester; papers have mostly a 

paper core coated with polyethylene resin layers on both 

sides. The front layer contains white titanium dioxide for 

high reflectivity, and the back layer contains a matting 

agent. Emulsions contain face-centered cubic silver bromide and silver chloride and may contain up to 10 weightpercent hexagonal silver iodide. A high degree of purity is 

required of the silver halides, the gelatin, and any other 

ingredients. 

Silver, which is the material responsible for producing 

the photographic image, is found in a number of different 

materials in facilities that process photographic materials. 

The leading sources of silver for recycling are photographic films, processing solutions, and papers. Once 

processed, silver is retained on the film and paper or transferred to the photographic processing solution. Silver in 

the processing solutions may be collected by using silverrecovery equipment, or the solutions can be sent off-site 

for recovery and subsequent delivery to a refinery. Silver 

may also be recovered from unprocessed black-and-white 

film and paper. Black-and-white film and paper include 

graphic arts film; medical, dental, and industrial X-ray 

film; and micrographic film. With color film and paper, 

however, all the silver and unused silver halides are 

removed during processing and accumulate in the fixer or 

bleach-fix solution. Therefore, processed color photographic film and paper (negatives, transparencies, and 

prints) do not contain appreciable amounts of silver 

(Eastman Kodak Company, 1998). 

ELECTRICAL AND ELECTRONICS SCRAP 

Electronics scrap, especially obsolete military electronics equipment, can be a fertile source of precious metals. The value is not always obvious because small quantities of precious metals are dispersed among large quantities of base metals, ceramics, and plastics. Gold and silver 

can be found in anodes, diodes, grid wires, integrated circuits, printed circuit boards, relays and contact points, and 

waveguides. Precious metals may also be found in batteries, cable connectors, capacitors, laminates, lead frames, 

resistors, semiconductors, slip-ring assemblies, and transformers (Hilliard and others, 1983). The percentage of pre­
SILVER RECYCLING IN THE UNITED STATES IN 2000 N7 

cious metals in electronics scrap is usually very small, but 

the value can be very high. Only small quantities of silver 

are consumed in individual items of electrical and electronics equipment, but the number of items in which it is 

consumed is very large. The National Electrical Manufacturers Association (2001) lists more than 50 categories of 

electrical components that incorporate silver as the contact 

material. 

Electronics scrap includes nonrechargeable batteries 

that contain silver compounds. The silver oxide-zinc cell 

has a cathode of Ag2O or AgO. These cells are characterized by a high-energy output per unit weight and a fairly 

constant voltage during discharge. Originally designed 

exclusively for the military, satellite applications, and space 

probes, these cells are now being used as power sources for 

calculators, cell phones, hearing aides, and wristwatches. 

Consumption of silver in batteries accounts for about 7 percent of total silver consumption by the electrical and electronics sectors (Roskill Information Services Ltd., 1992, 

p. 283–284).

Only a weak infrastructure exists in the United States 

to capture electronics waste. A few individuals and organizations have begun to realize the potential value of discarded electronics and have instituted procedures to 

reclaim valuable metals from these materials. The DOD 

and other Government agencies turn in most preciousmetals-bearing scrap to the DRMS. Once gathered and 

accounted for, the material is sent to a refiner. The finished 

product, 0.999 percent pure refined metal, is sent to the 

Defense Industrial Supply Center. The DRMS recovers 

precious metals from scrap property only when it makes 

good business sense. In some cases, such as the metal 

found in used silver batteries, precious metals are too 

costly to recover (Defense Reutilization and Marketing 

Service, 2001). 

JEWELRY AND STERLING WARE 

Products fabricated by jewelers and silversmiths consist largely of precious metals. Manufacturing scrap (new 

scrap) generated from these sources is, by its nature, of high 

value, and, therefore, intensive collection techniques are 

always practiced. Virtually everything is saved—clippings, 

fillings, lathe chips, production rejects, scrap from spinning 

sterling hollowware, and silver filled blanking scrap, and 

grindings are swept up. Crucibles, dust filters, floor mats, 

and polishing cloths are collected. Also old scrap, which 

includes broken, used, and obsolete items of jewelry and 

sterlingware, are returned by users to dealers for salvage of 

metal values. 

CATALYSTS 

A catalyst is a substance that changes the rate of a 

chemical reaction, but is itself not permanently changed 

in chemical form. A heterogeneous catalyst is one in 

which phase boundaries exist between the catalysts and 

the reacting substances; for example, a solid catalyst in a 

gas or liquid phase reaction. Heterogeneous catalysts that 

contain silver and silver compounds are widely used in 

research and industry for a variety of oxidation, reduction, and polymerization reactions. The products made by 

these processes, such as formaldehyde and ethylene 

oxide, have great economic value. Such catalysts can be 

deactivated by several different mechanisms, but deactivation is primarily the result of the accumulation of materials from the process stream onto the surface of the catalyst. This deposit results in substantial deterioration in 

catalyst performance. The catalyst activity or its ability to 

convert reactants is adversely affected by this deposition, 

and the catalyst is referred to as “spent” (Fung, 1993, 

p. 91–96).

The original performance of the spent catalyst can be 

restored by proper regeneration to remove accumulated 

surface materials (Kim and others, 1992, p. 39–46). 

Regeneration allows continued use of the same catalyst 

for several years. The number of times that a catalyst can 

be regenerated is limited, however, and eventually the catalyst must be replaced; catalysts may be regenerated two 

or more times. As a general rule, after a catalyst can no 

longer be regenerated to at least 75 percent of its original 

activity, it is reclaimed or discarded (Oil & Gas Journal, 

1998, p. 49). 

When catalysts are removed from service, they are 

sent to a toll refiner for recovery of the metal values. Toll 

refining is refining in which a fee, or toll, is charged to the 

owner of feedstock to be processed, to whom the refined 

product is returned for use or sale. The amount of silver 

used in catalysts for various chemical applications in 

2000 was estimated to be 1,300 t. Each year a number of 

catalysts are taken out of service and recycled. The effect 

on silver demand, however, is limited to the metal lost in 

the recycling process. Because silver is valuable, great 

care is exercised in monitoring all streams that enter and 

leave catalyst manufacturing and recycling sites to ensure 

that no significant amount of metal is lost. In the United 

States, yearly overall materials recovery rates of more 

than 99 percent are attainable (World Silver Survey 2000, 

2000, p. 43). 

MANUFACTURING WASTES AND SCRAP 

Manufacturing wastes and scrap accounts for about 15 

percent of silver consumption. The principal sources of such 

wastes are excess or rejected parts, experimental parts, 

material removed to eliminate defects or for testing, and 

above all, finishing waste consisting of cutting pattern losses, edge trim, and perforations. The silver content of these 

materials is almost always recovered by the manufacturer, 

and efficiency of recovery is better than 99 percent. Recovered silver is usually reused by the manufacturer inhouse. 

Information on this aspect of operations is seldom released 

by the manufacturer. 
N8 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES 

PROCESSING OF SILVER SCRAP 

PHOTOGRAPHIC WASTES 

A number of techniques are available for removing silver from silver-rich photographic processing solutions. Of 

these, three are used in virtually all practical methods of silver recovery—electrolysis, metallic replacement, and precipitation. 

Methods that are successfully used in other industries 

to recover silver, such as electrowinning, are not be applicable to photographic processing solutions because they tend 

to cause significant solution decomposition. 

Electrolysis 

In electrolytic silver recovery, a direct current is passed 

through a silver-rich solution between a positive electrode 

(anode) and a negative electrode (cathode). During this electrolytic process, an electron is transferred from the cathode 

to the positively charged silver, thus reducing it to its metallic state, which adheres to the cathode. In a simultaneous 

reaction at the anode, an electron is taken from some species 

in solution. In most silver-rich solutions, this electron usually comes from sulfite. An overview of the reaction is as 

follows: 

Cathode: -3 + e- → Ag(S -2 2O3)2 Ag0 + 2S2O3 

silver thiosulfate complex electron metallic silver thiosulfate 

Anode: 

SO3

-2 + H2O → SO4-2 + 2H+ + 2esulfite water sulfate hydrogen ions electrons 

In solutions high in iron, such as bleach fixes, the silver 

plating proceeds more efficiently under slightly alkaline 

conditions. Electrolysis produces a nearly pure metallic silver; any contamination by some surface reactions is slight. 

Purity of the plated silver is greater than 90 percent. 

Metallic Replacement 

Metallic replacement, which is also called cementation, is the reduction of the silver thiosulfate in solution to 

metallic silver by metallic iron, which is usually present as 

a steel wool. Commercial equipment used for the process 

is referred to as “metallic recovery cartridges.’ Steel wool 

was chosen as the reducing agent because of its large surface area. The steel wool is chopped and packed into a cartridge or wound on a core. Other sources of iron include 

iron particles glued to fiberglass, iron-impregnated resin 

blocks, or wound-iron screening materials (Eastman 

Kodak Company, 1999, p. 3–4). The following metallic 

replacement process is similar to the above electrolytic 

process: 

-2 2Ag(S2O3)2-3 + Fe0 → 2Ag0+ Fe+2 + 4S2O3 

silver thiosulfate metallic iron metallic silver ionic iron thiosulfate 

complex 

The final silver concentration is affected by flow rate, 

iron surface area, contact time, pH, original silver concentration, thiosulfate concentration, and the volume that passes through the cartridge. The silver concentration can be 

reduced to less than 5 milligrams per liter by using this 

method (Skoog and West, 1965, p. 425–439; Encyclopedia 

of Physical Science and Technology, 1987, p. 461–506). 

Precipitation 

Precipitation can remove silver from silver-rich solutions, thus reducing silver concentrations to low parts-permillion levels. Common precipitating agents are alkali 

metal salts of sulfide (sodium sulfide, potassium sulfide, 

and so forth) which form silver sulfide in solution. The precipitation method is not widely used because the silver concentration in solution must be determined accurately so that 

only stoichiometric amounts of sulfide are added to the silver-rich solution to prevent overdosing. Excess sulfide leads 

to the discharge of toxic hydrogen sulfide gas. 

Ion exchange, which refers to the substitution of an ion 

that is bound on a large polymer molecule, may also be used 

to remove silver from solutions. Ion exchange works best on 

such dilute solutions as washwater. Typically, ion exchange, 

which requires large capital investments and technical 

expertise, is used only when washwaters must meet very 

low silver regulatory limits. 

ELECTRICAL AND ELECTRONICS SCRAP 

Precious metals in electronics scrap are usually mixed 

with base metals, organics, and plastics. When end-of-life 

electronics components enter a recycling facility, they are 

first checked for reuse potential. Assemblies that can be 

resold are repaired, refurbished, and sold. If resale is not 

practical, then the equipment is demanufactured, and individual parts are separated for resale. The remaining material is shredded, ground, and separated. The next step is to get 

rid of valueless nonmetallic bulk materials by burning. After 

the mixed scrap has been incinerated, an ash and bits of 

metal and plastic residues remain. The ash and bits of metal 

are pulverized in a ball mill, which is a large closed cylinder that contains steel balls. As the mill rotates, the balls 

pound the ash, thus crushing it to a fine powder. This powder is then separated from oversize metallics through a 

screening process. The powder undergoes a final blending 

operation to complete the homogenizing process and is 

sampled before being assayed. The metallic fraction is 

homogenized by simply melting it in an induction or gasfired furnace. 

JEWELRY AND SILVERSMITH SCRAP 

Jewelry scrap may contain manufacturing rejects, trimmings, grindings and sweeps, but usually does not contain 

plastics or organic materials. Treatment of this material is 

similar to that of electronics and electrical scrap. Jewelry 

scrap that is all metal can be sent directly to the melting 
SILVER RECYCLING IN THE UNITED STATES IN 2000 N9 

furnace without an intermediate homogenizing operation. 

Grindings and sweeps are shipped to a refinery for silver 

recovery. 

Silver-plated tableware is produced by electroplating 

silver onto preformed shapes. The silver wastes generated in 

this type of processing are spills of silver-rich electrolyte, 

dilute wash solutions, and spent electrolyte. Usually, these 

silver-bearing solutions are collected together as a mill 

waste and processed to precipitate the silver before discharge as plant waste. The typical silver-plating mill waste 

solution may contain up to 250 parts per million silver. The 

solid wastes generated by the sterling silver industry are in 

many different forms and of widely different concentrations 

of impurities. The waste products include grinding and polishing dusts and abrasives, rejects, trimmings, turnings, and 

spillage and drosses from melting and casting. The different 

types of wastes are carefully segregated; any relatively pure 

materials are melted and assayed; and the composition 

adjusted for direct reuse. Wastes with low concentrations of 

silver are combined and melted, and the impure material is 

shipped to a refinery for processing (Butts and Cox, 1967, 

p. 74).

OUTLOOK 

The largest component of recycled silver comes from 

spent photographic film, paper, and solutions. These 

sources were increasing in 1999, and as photographic 

demand increased, the amount of silver recovered grew. 

The slight decline in the amount of silver used in photography in 2000 reflects the growing share of digital technology in the photographic market. The most significant 

impact of digital photography has been in the graphic arts 

and professional sector of the consumer market. The 

expected sizable growth of digital imaging will depend on 

a more-rapid acceptance of digital cameras by amateur 

photographers as well as a sizable switch by professional 

photographers from optical to digital cameras. The quality 

of images produced by digital cameras aimed at the amateur market improved steadily as the number of pixels in 

the charge-coupled device (CCD) sensors has increased to 

more than 1 million pixels by the end of 1999 from 300,000 

pixels in 1995. A CCD is a type of semiconductor that is 

sensitive to light and consists of a two-dimensional (2-D) 

array of individual elements, each of which is, in essence, 

a capacitor. A capacitor is an electric circuit element used 

to store a charge. A CCD’s charge is created when photons 

strike the semiconducting material and dislodge electrons. 

As more photons fall on the device, more electrons are liberated, thus creating a charge that is proportional to the 

light's intensity. With a 2-D array, an image can be captured. Digital images still have far inferior information 

capacity compared with a frame of 35-millimeter color 

negative film, which contains nearly 20 million pixels. Digital cameras also cost significantly more than the most 

widely used snapshot cameras and require considerable 

electric current for viewfinder, image processing, and display operations. It remains to be seen how well these disadvantages can be overcome in the short and long term. 

Output of ethylene oxide and other chemicals that 

require silver-based catalysts has been adversely affected by 

high natural gas and electric power costs. Compounding the 

problem is the slowing economy with a gross-domesticproduct growth of 1.5 percent in 2001. This will affect all 

catalyst application segments. 

As discussed above, obsolete computers, telecommunications, and DOD-related scrap contain significant quantities of silver and other precious metals. Obsolete computer 

scrap, which is being reclaimed at the rate of tens of thousands of metric tons each year, is projected to fall within this 

decade. Although the number of computers sold in the 

future and the number of units scrapped will increase 

sharply, the precious metals content per unit will decrease. 

Further, because of the miniaturization of computers and 

electronic components of the future, this scrap source will 

become extremely dispersed. Thus, once the existing inventory of older computers to be scrapped is depleted, precious 

metals from this source are expected to become less important. DOD-related scrap, however, will remain a significant 

source for the short and long terms. 

Overall, obsolete electronic scrap is diverse and contains materials other than precious metals. This diversity 

makes segregation and processing more difficult. New processing methods that could effectively segregate a wide 

range of electronics scrap into higher grade concentrates 

without losing too much of the precious metals in the 

process waste stream are in need of development. 

REFERENCES CITED 

Butts, A.B., and Cox, C.D., 1967, Silver, economics, metallurgy, and use: Princeton, N.J., D. Van Nostrand Company, Inc., 488 p. 

Chemical & Engineering News, 2001, Facts & figures: 

Chemical & Engineering News, v. 79, no. 26, June 25, 

p. 44.

Defense Reutilization and Marketing Service, [undated], 

2001, DRMS takes lead in environmental initiative to 

demanufacture electronic scrap, accessed May 15, 

2002, at URL http://www.dla.mil/. 

Eastman Kodak Company, 1998, Sources of silver in photographic processing facilities: Rochester, N.Y., Eastman 

Kodak Company, No. J–210, 8 p. 

Eastman Kodak Company, 1999, The technology of silver 

recovery for photographic processing facilities: 

Rochester, N.Y., Eastman Kodak Company, No. J–212, 

8 p. 

Encyclopedia of Physical Science and Technology, 1987, 

Photographic processes and materials: Boston, Mass, 

Academic Press, Inc., v. 10, 792 p. 
N10 FLOW STUDIES FOR RECYCLING METAL COMMODITIES IN THE UNITED STATES 

Fung, S.C., 1993, Regeneration of supported noble metal 

catalysts: American Chemical Society, Division of 

Petroleum Chemistry, Inc., v. 38, no. 1, February, 223 p. 

Heinen, H.J., McClelland, G.E., and Lindstrom, R.E., 

1979, Enhancing percolation rates in heap leaching of 

gold-silver ores: U.S. Bureau of Mines Report of 

Investigations 8388, 20 p. 

Heyl, A.V., Hall, W.E., Weissenborn, A.E., Stager, H.K., 

Puffett, W.P., and Reed, B.L., 1973, Silver, in Brobst, 

D.A., and Pratt, W.P., eds., United States mineral 

resources: U.S. Geological Survey Professional Paper 

820, p. 537–545. 

Hilliard, H.E., 2001, Silver: U.S. Geological Survey Mineral Commodity Summaries 2001, p. 148–149. 

Hilliard, H.E., 2002, Silver: U.S. Geological Survey Minerals Yearbook 2000, v. I, p. 70.1–70.12. 

Hilliard, H.E., Dunning, B.W., Jr., and Makar, H.V., 1983, 

Hydrometallurgical treatment of electronic scrap concentrates containing precious metals: U.S. Bureau of 

Mines Report of Investigations 8757, 15 p. 

Hull & Co., 1990, Heterogeneous catalyst systems: Greenwich, Conn., A multiclient study, January, 436 p. 

Hussey, S.J., Salisbury, H.B., and Potter, G.M., 1979, Carbon-in-pulp gold adsorption from cyanide leach slurries: U.S. Bureau of Mines Report of Investigations 

8368, 22 p. 

International Association of Electronics Recyclers, 2001, 

About electronics recycling, accessed November 13, 

2001, at URL http://www.iaer.org/aboutrecycling.htm. 

Kim, C.-S., Massoth, F.E., and Furimsky, Edward, 1992, 

Structure and catalytic activity of regenerated spent 

hydrotreating catalysts: Fuel Processing Technology, v. 

32, no. 1–2, November, 132 p. 

Mid-Atlantic Consortium of Recycling and Economic 

Development Officials, 2000 (March), Part V, Markets 

and economic development, End-of-Life computer and 

electronics recovery policy options for the Mid-Atlantic 

States (2d ed.), accessed May 15, 2002, at URL 

http://www.libertynet.org/macredo/2elecmkt.htm. 

National Electrical Manufacturers Association, 2001, Industrial 

control and systems control-circuit and pilot devices, 

NEMA Standards Publications JCS 5–2000, accessed 

October 15, 2001, via URL http://www.NEMA.org. 

Oil & Gas Journal, 1998, Regeneration industry helps refiners control costs, limit liabilities: Oil & Gas Journal, v. 

96, no. 41, October 12, 106 p. 

Reese, R.G., Jr., 1985, Silver: Bureau of Mines Bulletin 

675, 1985 Edition, p 729–739. 

Recycling Today, 2000, Re-boot re-use recycle: Recycling 

Today, v. 38, no. 4, April, p. 50. 

Roskill Information Services Ltd., 1992, The economics of 

silver in 1992 (4th ed.): London, United Kingdom, 

Roskill Information Services Ltd., 334 p. 

Skoog, D.A., and West, D.M., 1965, Electrode systems— 

Analytical chemistry: New York, Holt, Rinehart and 

Winston, Inc., 527 p. 

U.S. Environmental Protection Agency, 2000, Electronics 

reuse and recycling, WasteWise Update, accessed May, 15, 

2002, at URL www.epa.gov/wastewise/nbs/wanpda14.pdf. 

U.S. Geological Survey, 2000, 1998 assessment of undiscovered deposits of gold, silver, copper, lead, and zinc 

in the United States: U.S. Geological Survey Circular 

1178, 21 p. 

World Silver Survey	 2000, 2000, Fabrication demand: 

Washington, D.C., World Silver Survey 2000, May, 84 p. 

World Silver Survey 2001, 2001, Photography: Washington, 

D.C., World Silver Survey 2001, May, 84 p. 
SILVER RECYCLING IN THE UNITED STATES IN 2000 N11 

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. 

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

scattered, such as paints or fertilizers, making it exceptionally difficult and costly to recycle. 

downgraded scrap. Scrap intended for use in making a 

metal product of lower value than the metal product 

from which the scrap was derived. 

home scrap. Scrap generated as process scrap and consumed in the same plant where generated. 

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, 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 in percent 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. Metal 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: 

COS + OSE ×100 

OSG + OSI + decrease in OSS or − increase in OSS 

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. 

primary metal commodity. Metal commodity produced or 

coproduced from metallic ore. 

recycling. Reclamation of a metal in usable 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 × 100 

AS 

scrap consumption. Scrap added to the production flow of 

a metal or metal product. 

secondary metal commodity. Metal commodity derived 

from or contained in scrap.