Recover Mercury by Electrolytic Oxidation
An aqueous oxidation treatment process developed by the Bureau of Mines has been shown to be effective for treating carbonaccous gold ores to improve gold recovery. Ozone, chlorine, sodium hypochlorite (NaOCl), and calcium hypochlorite [Ca(OCl)2] were all shown to be effective reagents for oxidizing the carbonaceous material in the ore. However, generation of oxidizing conditions […]
Tungsten Metal & Tungsten Carbide Electrolysis
A high-temperature, two-phase extraction technique has been developed for the recovery of tungstic oxide (WO3) from tungsten-bearing minerals. The technique consists of dissolving scheelite (CaWO4) or wolframite in a system of two immiscible liquids-sodium chloride and sodium silicate-at 1,080° C. Tungstic oxide is converted to sodium tungstate (Na2WO4 ) and is transferred to the upper […]
Ion Exchange Resin to Recover Gold from Acid Solution
An ion exchange resin was found to quantitatively and selectively collect gold from acid solutions over a wide range of acid concentrations. Common metals at high concentration are not collected by the resin and they do not seriously interfere with the collection of gold. Alkaline cyanide solutions gradually destroy the capability of the resin to […]
Recover Aluminum by Electrowinning
The preparation of aluminum by molten salt electrolysis of AlCl3 was undertaken as part of the Bureau of Mines overall research program to develop methods for the utilization of domestic low-grade raw materials, de Beauchamp and Thomas and others summarized the preparation and manufacture of anhydrous AlCl3 from a variety of aluminiferous materials: aluminas, bauxites, […]
Electrowinning MischMetal
For many years, we conducted a research program on electrolytic preparation of rare-earth metals. Cerium, lanthanum, and neodymium, praseodymium, and didymium metals have been electrowon from their respective oxides dissolved in fluoride melts. Commercial production of mischmetal, a mixed rare-earth metal consisting essentially of cerium, lanthanum, neodymium, and praseodymium, is presently limited to electrolysis of […]
Roasting Copper Sulfides Chemistry
The roasting process is widely used in extracting copper from its sulfide ores. At present the development of a new process for winning copper from pelletized chalcocite concentrate is underway at the Bureau of Mines Twin Cities Metallurgy Research Center. In this process, the dead roasting of sulfide is followed by the reduction of oxide […]
Using Rock Bolts or Wire Rope to Increase Fractured Pillar Strength
In a room-and-pillar system of mining in which no artificial support is used (linings, sets, props, etc.), the weight of the overlying cover is sustained in part on the abutment and in part by the pillars. The pillars are usually the most important structural support element in a room-and-pillar system and their stability is responsible […]
Building a Junk Car Incinerator
Congress, by the Solid Waste Disposal Act of 1965, delegated to the Bureau of Mines responsibility for conducting research on solid waste problems. The accumulation of abandoned automobiles is one of these problems, and this paper reports the efforts of the Bureau’s Salt Lake City Metallurgy Research Center in attempting to resolve the abandoned car […]
Coal Free-Swelling Index Testing
The term “free-swelling” is applied to the behavior of some bituminous coals when heated under specified conditions. Damm defined the swelling of coal as the volume change that takes place when coal is heated. The softened coal can expand, for example due to gases being released on pyrolysis, in the direction away from the heating […]
How to Control Sulfur Oxide Emissions in Smelting
The domestic base-metal-producing industry has been challenged with the task of reducing the amount of sulfur oxides and other pollutants emitted by smelters treating sulfide ores and concentrates. This challenge has been imposed by legislation aimed at reducing air pollution. Standards for both ambient air quality and allowable emissions have been proposed and already are […]