How to Extract Silver from Refractory Ores
The recovery of silver from ores by hydrometallurgical techniques changed considerably toward the end of the 19th and in the early part of the 20th century. Metallurgical techniques, such as amalgamation, chloride roasting followed by amalgamation, hyposulphite leaching, and the Patio process (amalgamation of silver formed by the reaction of silver minerals with sodium chloride […]
Copper Cement Oxidation
Cement copper production has been increasing steadily because more mine waste from open pit mining is being leached and the copper recovered by cementation on scrap iron. Current estimates indicate that about 13.1 percent of the Nation’s production of primary copper is from this source. Cement copper is usually a crude product containing elemental copper, […]
How Plastic is Recycled
This is the age of plastics. Plastics are rapidly replacing metal, glass, and wood in parts of appliances, automobiles, prepackaged consumer goods, pipe, beverage containers, and furniture. The total sales of U.S. plastic for 1972, as shown in figure 1, was 24.19 billion pounds versus 19.9 billion pounds during 1971, an increase of over 20 […]
Chalcopyrite Sulfuric Acid Leaching Kinetics
Renewed interest in hydrometallurgical recovery of copper from copper sulfide during the past decade has resulted from demonstrated increased copper production from low-grade copper ores and interest in the development of non-smelting techniques. Of the sulfide minerals of copper, chalcopyrite (CuFeS2) merits special attention because of its relative abundance and because it is generally the […]
How to Steam Cure Bricks
In the processing of numerous types of minerals to recover their values, enormous tonnages of gangue materials are produced and discarded to storage areas near the processing plants. In this country, primary copper producers alone produce 125 million tons of tailings per year. Zinc, lead, asbestos, and roofing granule operations also produce large tonnages of […]
How to Clean Titanium Alloy Scrap
Recycled titanium scrap is mixed with titanium sponge for ingot production and, therefore, plays an important role in the production of mill products. Clean and segregated scrap is recycled fay producers that regard their scrap-recovery procedures as proprietary. Unless a rigorous procedure is observed for segragating titanium scrap by alloy content, the scrap is not […]
How to Recover Metals from Zinc Smelter Residue
Primary smelting of zinc in horizontal retort distillation furnaces leaves a residue consisting of the following: unburned carbon, iron as metal shot and stringers, copper inclusions in the iron as metal and as sulfides, silver in solid solution in the copper, and glassy slag. After removal from the retorts and cooling, the residue is crushed […]
Use of Cryogens Liquid Nitrogen to Recycle Scrap Metals
Scrap such as insulated copper wire, small motors, automobile tires, and nonferrous concentrates from automobile shredders contains materials that become brittle at low temperatures and other materials that remain malleable. Crushing of the chilled materials to shatter the embrittled portion followed by magnetic separation, screening, and/or gravity separation was studied for recovering the individual components. […]
Mica Beneficiation
In recent years, more than 99 percent of the domestic mica produced has been scrap and flake mica (mica which does not meet specifications for sheet mica and which is used for producing fine-ground mica). There has been a continued increase in mica production for several years. The 1969 production of scrap and flake mica […]
Chlorine Leaching Copper
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 […]