SIC 1044 Silver Ores

Contenidos

• NAICS CODE(S).
• INDUSTRY SNAPSHOT.
• ORGANIZATION AND STRUCTURE.
• Extraction and Refining.
• BACKGROUND AND DEVELOPMENT.
• Early History.
• Silver in Recent Times.
• Silver Supply and Stocks.
• Consumption.
• Silver-Free Photography.
• Silver and the Environment.
• CURRENT CONDITIONS.
• INDUSTRY LEADERS.
• AMERICA AND THE WORLD.
• RESEARCH AND TECHNOLOGY.
• FURTHER READING.

SIC 1044

This category covers establishments primarily engaged in mining, milling, or otherwise preparing silver ores, including the production of bullion at the mine or mill site.

NAICS CODE(S)

212222

Silver Ore Mining

INDUSTRY SNAPSHOT

Most world silver is produced as a byproduct or coproduct in the mining of other metals—such as copper and gold, and, to a lesser degree, lead and zincem. The outlook for silver production tends to overlap with the outlooks for other metals. Primary producers, which account for roughly one-third of world silver supply, are more vulnerable to swings in the historically volatile silver market than diversified metal producers.

Silver entered the new millennium with relatively static prices, fluctuating less than $1.00 between its high and low prices for the third consecutive year. In early 2001, silver reached a temporary high of $4.87 per ounce before slipping to a low of $4.16 per ounce. This drop can be attributed in part to a 10 percent decrease in global industrial silver demand during that period. Worldwide, photographic demand was slightly less than in 2001, whereas the demand for silver in jewelry increased that year. Silver trading remained relatively flat until the September 11, 2001, attacks on the World Trade Center, which closed markets until September 17, causing silver prices to rise to $4.32 per ounce—eventually reaching $4.65 in early October—as concerns arose about the vaults of silver buried under the rubble of the World Trade Center. After a brief downward trend, prices rose again in December to $4.65 as investors looked for a safe haven in a climate of economic uncertainty. Overall, silver was down 12 percent in 2001 from the average price of $5.00 in 2000.

In 2002, United States mines produced approximately 1,470 tons of silver with an estimated value of $214 million. There were 21 principal refiners of commercial-grade silver producing an estimated 2,900 tons of output. Approximately 30 fabricators consumed more than 90 percent of the silver used in the arts and industry. Mainly an industrial metal, industrial and technical uses of silver, including photographic materials and electrical and electronic products, are by far more in demand than aesthetic silver uses, which include jewelry, tableware, and coinage. In 2001, domestic industrial consumption fell by approximately 480 metric tons to 2,450 metric tons. Total 2001 U.S. consumption of silver, estimated at 5,300 metrics tons, fell 749 metric tons from the previous year. Domestic mine production of silver stood at 1,240 metric tons in 2003, down 8 percent from 1,420 in 2002. Those figures, reported by U.S. geological Survey, indicated the lowest silver mine production levels since 1994.

That trend continued into 2004, with domestic mine production decreasing further to 1,200 tons of silver with an estimated value of $184 million. Alaska had replaced Nevada as the principle U.S. silver producer. An estimated 270,000 tons of silver make up the world's resources, according to the U.S. Geological Survey. Major producers include China, Mexico, and Australia. With the upturn in the economy, promising new technology advances were expected to be at the forefront of the silver industry in 2005.

ORGANIZATION AND STRUCTURE

Most silver is produced from argentiferous ores—the sulfides of lead, copper, and zinc—which may contain varying amounts of silver, depending on their location. Silver is also found as deposits of native silver (usually in alloy form), as sylvanite (gold and silver telluride) ores, and in many naturally occurring minerals, including galena (lead sulfide), argentite (silver sulfide), cerargyrite (silver chloride), and others.

Extraction and Refining

Various methods are employed to extract silver or a combination of silver and gold from ores, scrap, alloys, and used photographic materials. As most silver is a byproduct of copper, lead, and zinc ore treatment, the precise process differs with each ore. In every case, however, the silver is finally collected in the form of crude silver or silver-gold bullion. The former is refined by a process involving smelting in a furnace with lead oxide, fluxes, and a reducing agent to produce a purer alloy of silver and gold called dore. An oxidized lead residue melts away in the process.

Two methods—electrolysis and parting—are used to separate silver and gold in silver-gold bullion. In electrolysis, electric current is passed through a silver nitrate water solution, with silver, gold bullion, and dore serving as the anode. In the parting method, the dore is dissolved in a bath of hot concentrated sulfuric or nitric acid. Gold is recovered from the residue, and the clear solution is treated with ferrous sulfate to precipitate the silver, which is filtered off and melted into bars. In 2001, approximately 1,100 tons of silver were recovered from recycled materials according to the U.S. Geological Survey, Mineral Commodity Summaries.

BACKGROUND AND DEVELOPMENT

For thousands of years, silver's aesthetic and practical value, as well as its relative rarity, have earned it a position among precious metals. As a noble metal, it resists oxidation and demonstrates excellent properties of conductivity, making it particularly useful in both ornamentation and as a practical conductor of electricity and heat for numerous applications. Although it tarnishes easily in the presence of certain sulfur compounds and scratches easily in its pure form, it is the whitest of all metals and an excellent reflector of light—capable of reflecting up to 95 percent of incident light rays in the visible spectrum. Silver's chemical symbol, Ag, was obtained from the Latin name for silver, Argentum, which means bright and shining.

Early History

Silver was one of the first metals after gold and copper to be molded by humans, and silver artifacts have been found in Near Eastern tombs dating back to 4,000 B.C. The Romans developed a method of separating silver from ore by a heating process, which was used into the Middle Ages, when silver-copper mines were exploited in central Europe. By the sixteenth century, the Spaniards had discovered enormous silver and gold deposits in Central and South America. Mexico largely supported Spanish colonial wealth until its independence in the early nineteenth century. Into the 1990s, however, much of the silver remained, leaving Mexico the world leader in silver production. Minas de las Rayas, a mine that began operating in 1558, as well as other mines and general sites, still produced silver into the 1990s. Penoles' Fresnillo Mine, known as the richest silver mine in the world and in operation...