The high reactivity of chlorine as an oxidizing agent in leaching ore has long been recognized, but chlorine has not been extensively used because of high costs and because of the corrosiveness of acid chlorine solutions. As early as 1848, the use of aqueous chlorine solution was proposed for extracting values from gold ores, and … Read more
Cementation of copper onto iron is a historically old process for recovery of copper from leach solutions. Although about 13 percent of the Nation’s primary copper production is from cementation, this process remains more of an art than a science. The literature on cementation is extensive, but a thorough review shows that until about 1965 … Read more
The recovery and recycling of metals from process wastes is a major research effort of the Bureau of Mines. The present work was undertaken by the Rolla Metallurgy Research Center to develop data that could be used in a pyrometallurgical process to recover zinc and lead from the flue dust generated in the secondary smelting … Read more
Chromium is essential to modern industry, and there are few acceptable substitutes for most of its metallurgical and chemical applications. In 1979 the United States consumed 610,000 tons of chromium, of which about 10 pct was supplied from secondary sources from within the country; the remainder was imported. Annual consumption is projected to grow to … Read more
The United States depends on imports of bauxite and alumina for most of its aluminum requirements. To reduce this dependence, the Bureau of Mines conceived a raw materials-process technologies matrix as a means of systematically investigating the technology options available for processing domestic aluminum resources. In 1973, a research program was initiated based on this … Read more
As part of the mission of the U.S. Department of the Interior’s Bureau of Mines to help insure the continued viability of the domestic minerals and materials economy, and to help maintain an adequate minerals base, research was conducted to investigate in situ leach techniques for extraction of copper from a chalcopyrite ore. Successful application … Read more
Present copper extraction technology is based principally on pyrometallurgical processing of sulfide concentrates in which high-temperature air-roasting and air-smelting generates large quantities of sulfur dioxide. Because of very stringent environmental standards and increasing cost of energy, there has been a renewed interest in hydrometallurgical processes for recovering copper from sulfide flotation concentrates. Potential advantages of … Read more
Mercury is customarily recovered from its ores by roasting sulfide minerals and condensing the vapors to obtain the metal. The process is efficient from the standpoint of mercury removal from the calcine; however, vapor and particulate losses in the condensing system, as well as the loss owing to recombination of the mercury with sulfur, can … Read more
Projections for the expanded use of rhenium as a catalyst in the catalytic reforming of gasoline stocks to make low-lead gasoline prompted the Federal Bureau of Mines to investigate techniques for rhenium and molybdenum separation and recovery. In current technology, rhenium is recovered from the roaster gases produced during the oxidation of molybdenite concentrates. The … Read more
About 85 percent of the copper produced in the United States is derived from copper sulfide ores by flotation, smelting, and electrolytic refining. Chalcopyrite is the predominant copper sulfide mineral in vein and disseminated porphyry-type deposits. Projected production of chalcopyrite concentrates from copper deposits now being developed and from expanded operations will soon exceed existing … Read more