Silver mining

PROUSTITE. This ruby-silver mineral crystallizes in the hexagonal system its name is a product of its scarlet-to-vermilion color when first mined It is a silver arsenic sulfide. AgjAsS, of adamantine luster Hardness of 2-2,5 specific gravity of 5.55-5.64. Usual crystal habit is prismatic to rhombohedral more commonly occurs massive. Conchoidal to uneven fracture transparent to translucent color, scarlet to vermilion red. Light sensitive must be kept in dark environment to maintain its primary character. A product of low-tcmpcraturc formation in most silver deposits. Notable world occurrences include the Czech Republic and Slovakia, Saxony, Chile and Mexico. Found in minor quantities in the United States the most exceptional occurrence at the Poorman Mine, Silver City District. Idaho where a crystalline mass of some 500 pounds (227 kilograms) was recovered m 1865, It was named for the famous French chemist, Louis Joseph Proust. 

Various kinds of Pyrites are found in our mines-Silver Colour, almost Gold Colour, True Gold Colour like Galena, Ashen Colour, and Iron Colour. 

Iron mines Lead mines Molybdenum mines Nickel mines Silver mines Titanium mines Zinc mines Zirconium mines Coal mines Fluorspar mines Granite mines Limestone mines... 

At the beginning of our chronological times, Spain had taken over as the main supplier of silver ore and silver metal. Native silver was found, but usually the mined silver was a sulfide mixed with lead sulfide. 

Fluorspar occurs in two distinct types of formation in the fluorspar district of southern Illinois and Kentucky in vertical fissure veins and in horizontal bedded replacement deposits. A 61-m bed of sandstone and shale serves as a cap rock for ascending fluorine-containing solutions and gases. Mineralizing solutions come up the faults and form vein ore bodies where the larger faults are plugged by shale. Bedded deposits occur under the thick sandstone and shale roofs. Other elements of value associated with fluorspar ore bodies are zinc, lead, cadmium, silver, germanium, iron, and thorium. Ore has been mined as deep as 300 m in this district. 

Lead and 2inc minerals are so intimately mixed in many deposits that they are mined together and then separated. Silver minerals are frequendy found in association with galena. 

Nickel [7440-02-0] Ni, recognized as an element as early as 1754 (1), was not isolated until 1820 (2). It was mined from arsenic sulfide mineral deposits (3) and first used in an alloy called German Silver (4). Soon after, nickel was used as an anode in solutions of nickel sulfate [7786-81 A] NiSO, and nickel chloride [7718-54-9] NiCl, to electroplate jewelry. Nickel carbonyl [13463-39-3] Ni(C02)4, was discovered in 1890 (see Carbonyls). This material, distilled as a hquid, decomposes into carbon monoxide and pure nickel powder, a method used in nickel refining (5) (see Nickel and nickel alloys). 

Deposits. Selenium forms natural compounds with 16 other elements. It is a main constituent of 39 mineral species and a minor component of 37 others, chiefly sulfides. The minerals are finely disseminated and do not form a selenium ore. Because there are no deposits that can be worked for selenium recovery alone, there are no mine reserves. Nevertheless, the 1995 world reserves, chiefly in nonferrous metals sulfide deposits, are ca 70,000 metric tons and total resources are ca 130,000 t (24). The principal resources of the world are in the base metal sulfide deposits that are mined primarily for copper, zinc, nickel, and silver, and to a lesser extent, lead and mercury, where selenium recovery is secondary. 

The American cordillera extending from Alaska to BoUvia has been the most productive source of silver wherever it is associated with Tertiary age intmsive volcanic rocks, mosdy concentrated by hydrothermal action. The largest producing mine in the cordillera is at Potosi, BoUvia, where the total silver output since the 1500s is estimated at over 31,000 metric tons. 

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. 

In the Commonwealth of Independent States (CIS, formerly the USSR), nearly 50% of the CIS production comes from Ka2akhstan. Silver is produced from the lead—2inc mines at Ostkamen, Shymkent, and Leninogorsk (ca 1000 t) and also in Russia s Far East, where it is a by-product of the tin deposits near Khabarovsk, and of the copper and gold deposits in the Ural Mountains. 

Canada s most productive district is in the Canadian shield at Cobalt, Ontario. Nearly 97% of the silver values in this pre-Cambrian age ore were found as great slabs of nearly pure silver. One slab was 474 kg. The huge open-pit Kidd Creek Mine has had an aimual output of over 80 t of silver. 

Mine Production of Silver. World production of silver by region is given in Table 3. Some 900,000 metric tons are estimated to have been mined since early times. By the year 1500 world mine production was about 50 t/yr. In 1992 world production exceeded 14,900 metric tons. EoUowing the breakup of tfie Soviet Union, previously undisclosed data showed that the USSR led wodd silver production during 1979—1980 at about 1550 metric tons. During the early 1990s the production in this region exceeded 2000 t/yr. 

U.S. silver production from 1985 to 1994 averaged 1588 t/yr. Less than one quarter of this output comes from silver mine districts, however. About half is as by-product of gold mines about one quarter comes from copper and lead—2inc mines. The silver production in Mexico from 1985 to 1994 averaged 2256 t/yr, and Pern, at the southern extremity of the cordillera, where silver is a by-product of copper and lead—2inc mines, averaged 1810 t/yr. 

Secondary Silver Recovery. The consumption of sdvei normally exceeds its mine production therefore recovery from scrapped products. ... 

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). 

Like selenium, tellurium minerals, although widely disseminated, do not form ore bodies. Hence, there are no deposits that can be mined for tellurium alone, and there are no formally stated reserves. Large resources however, are present in the base-metal sulfide deposits mined for copper, nickel, gold, silver, and lead, where the recovery of tellurium, like that of selenium, is incidental. 

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. 

Montana. These deposits consist of stibnite and other sulfide minerals containing base metals and silver or gold. Ores of the complex deposits are mined primarily for lead, copper, 2inc, or precious metals antimony is a by-product of the treatment of these ores. 

Revenues from low grade copper mines are also gained from such by-products as molybdenum [7439-98-7] silver, gold, selenium [7782-49-2] and tellurium [13494-80-9],... 

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