Thiourea
Thiourea (H2NCSNH2) is an organic compound, the crystals of which dissolve in water to yield an aqueous form stable in acidic solutions. The unique feature of thiourea is that, in aqueous solution it reacts with certain transition metal ions to form stable cationic complexes. For example, the following generalized reaction illustrates the complexing role of […]
Sulfurous Acid Leaching of Kaolin for Preparing Alumina
The Bureau of Mines is conducting a program to evaluate technology for the recovery of alumina from domestic resources. Bauxite, the major alumina ore, is mainly imported. In recent years, bauxite-producing countries have formed an organization that attempts to control the supply and price of bauxite. The United States has only limited reserves of bauxite […]
Copper & Nickel Solvent Extraction
Nickel and copper were co-extracted from ammoniacal ammonium sulfate leach liquors (pH-9.5) with LIX 64N extractant in a laboratory-size mixer-settler continuous circuit. Three extraction stages resulted in >99-pct extraction of nickel, substantial copper extraction, and essentially no cobalt extraction from leach liquors. A crowd stage reduced the ammonia loading on the solvent by maximizing nickel […]
Uranium Leaching Lixiviants
This Bureau of Mines publication provides information to assist in selecting a lixiviant (leach solution) for in situ uranium leaching. The cost, advantages, and disadvantages of lixiviants currently used and proposed are presented. Laboratory and field tests are described, and applications of geochemical models are discussed. Environmental, economic, and technical factors should all be considered. […]
Remove Iron by Solvent Extraction in Aluminum Chloride Leach Solution
As part of its mission to maintain an adequate supply of minerals to meet national needs and maximize mineral production from domestic sources, the Bureau of Mines is investigating the recovery of alumina by hydrochloric acid leaching of kaolinitic clay. Most iron impurities are leached from the clay along with the alumina and must be […]
Chlorine Oxygen Leaching Process
To increase metal recoveries and to minimize pollution by improved extraction technology, the Bureau of Mines investigated a hydrometallurgical technique to recover copper, lead, nickel, and cobalt from lead smelter mattes. The metals were converted from insoluble sulfides to soluble chlorides using a HCl-Cl2-O2 leaching system. Parameters studied in a 50-gallon, glass-lined reactor were the […]
Recovery of Lithium by Chlorination
The Bureau of Mines studied the extraction of lithium from lithium- containing clays by chlorination with hydrogen chloride (HCl). In bench-scale laboratory investigations, HCl-H2O mixtures were used to selectively chlorinate lithium, but not calcium or magnesium, in lithium-containing clays. The addition of calcium carbonate to the clay was found to improve the lithium recovery. Reaction […]
Making Acid Iron Ore Pellet
In 1976 CVRD started the investigation of organic binders application for iron ore agglomeration. The ore was mixed in a Eirich Mixer with quantities of Peridur ranging from 0.1 to 0.4% and pellets were prepared in a laboratory disk. At first the results were not satisfactory at all. The wet and dry compressive strength and […]
How to Recover Chrome Metal from Scrap Alloy
Fluidized-Bed Roasting of Chromium Sulfide The chromium concentrate produced either directly as flotation tails or indirectly as a leach residue is composed primarily of chromium sulfide with chromium comprising about 80 percent of the metal content. Nickel and molybdenum sulfides would be present in the flotation tails along with heavy metal oxides. The leach residue […]
Dump Leaching Copper Recovery
Leaching of porphyry copper mine strip wastes and low-tenor ores provides a substantial part of U.S. copper needs. Dump leaching requires years to extract part of the copper, and leach dumps often become impermeable owing to precipitation of iron salts which greatly reduces the copper leaching rate. In an effort to improve dump leaching technology, […]