To reuse chromium, nickel, and molybdenum now lost in stainless and specialty steel-making wastes, and simultaneously to overcome the current environmental problem resulting from landfilling these wastes. A variety of stainless and specialty steelmaking wastes are agglomerated and recharged into the plant’s electric arc furnaces. How It Works Stainless and specialty steel-making wastes such as bag-house … Read more
As part of its effort to produce cell-grade alumina from clay, the Bureau of Mines investigated the hydrogen chloride gas-sparging crystallization of aluminum chloride hexahydrate (ACH) from aluminum chloride liquor, to provide information for optimizing the crystallization operation. Four parameters important in controlling the crystallization of the aluminum chloride hexahydrate and the concentration of impurities, … Read more
We studied the precipitation of copper from dilute acidic sulfate solutions using shredded automobile scrap in a rotary drum. The tests established that the scrap in the rotary drum precipitated copper faster and more completely than shredded, detinned, tinplate scrap in a launder, with comparable iron consumption. Although power is required to rotate the drum, … Read more
To help assure an ample domestic supply of zinc and other essential minerals which provide the foundation of the Nation’s economy and security, the Bureau of Mines is investigating an aqueous chlorine-oxygen leaching procedure to produce zinc chloride from complex sulfide concentrates and is also studying methods of fused-salt electrolysis to produce special-high-grade zinc metal … Read more
As part of the goal to develop technology that can meet critical and strategic needs of minerals and metals, the Bureau of Mines is investigating a procedure for selectively extracting nickel, cobalt, and copper from low-grade domestic laterites. Although the Nation produces less than 10 pct of the primary nickel it consumes and essentially none … Read more
CuSO4 Crystallization for Typically Acidic Extraction: A small body of acid-leachable copper ore or a small existing stream of copper-bearing acidic mine water is often unable to justify a plant to produce cathode copper. Electrowinning is capital intensive, and small reserves are generally considered higher risks for financing. Electrowinning is also intensive in electric power and … Read more
The objective of this investigation was to reduce toxic Cr6+ in various waste processing liquors to less toxic Cr3+ while simultaneously removing copper. In addition to recovering a valuable copper product, removal of copper and reduction of Cr6+ in these liquors will substantially decrease the chemical demand and increase efficiency in waste treatment operations associated … Read more
Etching solutions containing hexavalent chromium ions (e.g., chromic acid) are used in brass finishing, printed circuit board etching, preparation of plastic for plating, anodizing, and various other industrial surface treatment operations. As the solutions are used, hexavalent chromium ions are reduced to their trivalent state, contaminants accumulate in the solution, and the effective acid concentration … Read more
Dielectrophoresis, or dielectric separation, can be defined as the separation of particles according to their dielectric properties. Directly related to the dielectric properties of a particle is the particle’s dielectric constant (K). The difference in K of minerals is often much greater than the differences in density, magnetic susceptibility, or electrical conductivity. To date, several … Read more
Continuously separate mixture of non-magnetic materials (such as scrap, precious metals, or certain ores) at a reasonable cost. Nonmagnetic materials of different densities are rapidly float/sink separated by an augmented lifting force produced in a magnetic fluid (liquid) by the effect of an external magnetic field. The magnetic fluid is a colloidal suspension of magnetite … Read more