United States silver

The cost of various silver compounds is a function of the silver market price. In 1980, the estimated usage of silver ia the United States was 3730 metric tons (120 X 10 troy oz) (23). This silver is derived from silver mined within the United States silver recycled or reclaimed from secondary sources, eg, coiaage, flatware, jewelry, and photographic materials and imported silver. In 1980, Canada, Mexico, and Pern, the principal exporters of silver to the United States, shipped 1670 tons (53.8 x 10 troy oz) as silver buUion and silver compounds. U.S. imported 2799 t and exported 964 t ia 1988 (23). 

Old United States silver coins, which are 10 0% Cu in Ag, melt completely at 875 0°C, pure silver melts at 960 0°C What is the molal freezing-point constant for Ag9... 

In both preceding cases, the demands to the electrolysis unit are limited, since there is no need to keep the silver content in the fixer tank constantly low. A steady state silver concentration in the fixer between 3 and 5 g/1 is acceptable, since this causes no substantial loss of fixation speed. 

Uses. Silver fluoride has found many laboratory and special industrial appHcations. It is used as a soft (nHld) fluorinating agent for selective fluorination (7—17), as a cathode material in batteries (qv) (18), and as an antimicrobial agent (19). Silver fluoride is commercially available from Advance Research Chemicals, Inc., Aldrich Chemicals, Cerac Corp., Johnson/Matthey, PCR, Atochem, and other sources in the United States. The U.S. price of silver fluoride in 1993 was 1000— 1400/kg and the total U.S. consumption was less than 200 kg/yr. 

Sa.Ia.rs and Lakes. Brines having high lithium concentration are found in salars of northern Chile, southwestern Bohvia, and northwestern Argentina. Brines of lower lithium concentration are found in salars in the western United States and the Tibetan Plateau. Brines pumped from beneath the surface of the Salar de Atacama (Chile) and Silver Peak (Clayton Valley, Nevada) are used for commercial production of lithium uti1i2ing solar evaporation (see Chemicals frombrines). The concentration of selected ions in brines from salars and lakes of potential commercial interest worldwide are shown in Table 1. 

Mexico, the world s leading producer of silver since the Spanish conquest, obtains virtually its entire silver production from lead—2inc mines in the central cordillera. Mexico retained its dominance in silver production until the discovery of the Comstock Lode in Nevada in 1859. Discoveries in Colorado, Ari2ona, and Montana placed the United States as the world s top silver producer from 1871 until 1900. As these mines played out, Mexico s vast resources returned it to its former position of dominance. 

The most important body of primary silver ore in the United States in the 1990s is located in Silver Valley, the Coeur d Alene Mining District of Shoshone County, Idaho, which produces >200 t/yr of silver. The main ore mineral is tetrahedrite [12054-35-2] associated with sulfides of lead, copper, iron, and 2inc. 

Silver Thick Films. About half of the silver consumed in the United States for its electrical properties is used by the electronics industry. Of this amount some 40% is used for the preparation of thick-film pastes in circuit paths and capacitors. These are silk-screened onto ceramic or plastic circuit boards for multilayer circuit sandwich components. 

Sputtered silver mirrors are used for solar energy (qv) collectors and astronomical telescope mirrors. Approximately 3 t/yr of silver are used in the United States for low emissivity windows. 

New silver accounts for only a portion of the silver used ia the United States. Recycled silver makes up the difference. AvailabiUty of recycled silver depends on market price. As the market price iacreases, so does the flow of recycled silver (see Recycling, nonferrous metals). The New York price reached an all-time high of 1543/kg ( 48.00/troy oz) onjanuary 21, 1980, primarily as a result of speculation. The price fell to 347.30/kg ( 10.80/troy oz) four months later as the pressure of speculative activity ia the silver market lessened. Comprehensive reviews of the silver market are published yearly the New York prices between 1985 and 1988 were as follows (23). 

Open-pit zinc mining is not common, since most mines ate below the surface. The Kidd Creek Mine in Ontario, Canada, is a combination open-pit—underground mine. It is one of the richest deposits in the world with an estimated 62.5 x 10 t grading 7.08% zinc, 1.33% copper, and 151 g silver (14). Underground mining methods include room-and-pdlar, shrinkage, cut-and-fill, and square set. In the United States, ca 20 mines account for more than 98% of zinc production. 

Economic Aspects and Uses. In 1976, one-third of the lithium produced in the United States was extracted from brines of Seades Lake and Silver Peak (44,45). Since then, lithium production at Seades Lake has been discontinued and the lithium concentration at Silver Peak is decreasing. During the 1980s lithium extraction was started at the Salar de Atacama, Chile. This is the largest lithium production plant in the wodd using brine as its raw material. 

New technology and development of brine reserves are increasing each year in the United States and abroad. This affects the uses and price of brine chemicals. For example, development of the Salar de Atacama in Chile in the 1980s as the largest producer of brine lithium in the world has affected lithium production and prices worldwide. Lithium production from Seades Lake brine has been discontinued, and the Silver Peak operation in Nevada is in a slow production decline caused by weaker brine grades. 

Silver. About 72.3 t of silver were electroplated in the United States (8) in 1989. Silver is used in dinnerware and hardware or functional apphcations. This usage is reported to be fairly stable (see Silverand silver alloys). 

The reaction is carried out over a supported metallic silver catalyst at 250—300°C and 1—2 MPa (10—20 bar). A few parts per million (ppm) of 1,2-dichloroethane are added to the ethylene to inhibit further oxidation to carbon dioxide and water. This results ia chlorine generation, which deactivates the surface of the catalyst. Chem Systems of the United States has developed a process that produces ethylene glycol monoacetate as an iatermediate, which on thermal decomposition yields ethylene oxide [75-21-8]. 

Ethylene oxide, the simplest epoxide, is an intermediate in the manufacture of both ethylene glycol, used for automobile antifreeze, and polyester polymers. More than 4 million tons of ethylene oxide is produced each year in the United States by air oxidation of ethylene over a silver oxide catalyst at 300 °C. This process is not useful for other epoxides, however, and is of little value in the laboratory. Note that the name ethylene oxide is not a systematic one because the -ene ending implies the presence of a double bond in the molecule. The name is frequently used, however, because ethylene oxide is derived pom ethylene by addition of an oxygen atom. Other simple epoxides are named similarly. The systematic name for ethylene oxide is 1,2-epoxyethane. 

If you had lived in earlier times in the United States, you might have bought a horse or a house with 10 coins made of gold. You may still have some old dimes, quarters, and dollars made of silver. Copper pennies, of course, are an everyday sight. These three transition elements have been used as money since ancient times in almost all parts of the world. 

Today, however, pure gold and silver are too scarce and valuable to be used as coins. The United States government keeps huge bars of these metals in vaults, as a reserve. Only copper, the most abundant of the three, is still in daily use as money in the United States. 

Estimated release of silver to the environment in the United States in 1978... 

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