Recover Metals from Electroplating Wastes
The waste-plus-waste treatment method can be successfully used on a variety of acid and alkaline electroplating wastes. The method is economically attractive because of the low cost of the waste-plus-waste addition step: No additional reagents are necessary, and the metal values are concentrated. In the five waste-plus-waste combinations investigated, combination of the two wastes caused […]
Convert Hydrous Calcium Sulfate to Hydrogen Sulfide
During the period 1960-65 sulfur consumption in the United States rose 40 percent to 7.96 million long tons. Since 1963, while demand has exceeded production, withdrawals from producer stocks have met the deficit. An assured steady supply of sulfur is essential for the national interest. Its applications are so diverse that the quantity used is […]
How to Measure Surface Tension of Molten Metals
We been performing research on soft soldering with the objective of improving the strength of solder joints at elevated temperatures and pressures. Surface or interfacial phenomena and the factors affecting these phenomena are of major importance in soldering and brazing. A knowledge of the surface tension of the molten materials involved, such as the filler […]
Chalcocite Oxidation Roasting
The Bureau of Mines Twin Cities Metallurgy Research Center is engaged in a study to uncover a cleaner, more direct pyrometallurgical process for winning copper from sulfides. The .initial target is low-sulfur concentrates containing primarily chalcocite (Cu2S). Development work, still in progress, points to a new and, perhaps, improved smelting procedure in which the following […]
How to Evaluate Face Respirator Fit
For the past few years there has been increasing interest among respirator users in determining quantitatively the degree of protection afforded by protective respiratory devices. Overall protection depends on both the efficiency of filters and/or sorbents used and the tightness of seal around the edges of the facepiece. The Bureau of Mines first introduced quantitative […]
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 […]