David Among several suggested new processes for treating marginal ores in the United States, none is more intriguing than the possibility of extracting metals from low-grade materials by the action of microorganisms. One phase of a Federal Bureau of Mines investigation toward developing such a procedure was to isolate and identify specific chemosynthetic iron- and sulfur-oxidizing … Read more
This report stems from a study by the Bureau of Mines of the possibility of reducing coal filter-cake moisture by applying radiant heat directly to the filter cake while under vacuum during the drying phase of the filter cycle. One disk of a 4-foot-diameter vacuum filter was equipped with gas-fired radiant-heat generators and the effect … Read more
The results of this investigation indicate that the titanium-gadolinium phase diagram is composed of a single eutectic reaction and a peritectoid reaction at the alpha-beta transformation. The eutectic isotherm has been established at 1,240 ± 10° C. and extends from approximately 1 pct. gadolinium to beyond 99 pct. gadolinium at this temperature. The solid solubility … Read more
The following conclusions are drawn from the results of these investigations: The reflux leaching method is an effective means for extracting aluminum from crude Al-Si alloy. Aluminum obtained by this method will contain from 1 to 6 percent silicon, 0.04 to 0.8 percent iron, and 0.01 to 0.9 percent titanium. With only minor changes in … Read more
Zirconium diboride of a quality comparable to that produced commercially from zirconium dioxide may be synthesized directly from zircon. The quantities of residual carbon and silica are not excessively high, but it is believed that some refinements in procedure may lower these percentages. The grain size of the final product has been demonstrated to be … Read more
The investigation of the zirconium-gadolinium equilibrium diagram revealed a eutectic system with limited terminal solubilities and one peritectoid reaction. The eutectic point occurs at about 82 percent gadolinium. The eutectic isotherm, at 1,220° C., extends from about 12 to 99+ percent gadolinium. The peritectoid isotherm, at 890° C., involving the alpha-beta transformation of zirconium, extends … Read more
The mineral dressing research here reported is part of a continuing program by the Bureau of Mines to develop new or improved concentration processes for oxidized or partly oxidized lead and zinc ores. A sample of low-grade sulfide-oxide, lead-zinc ore from Jasper County., Mo., containing galena, cerussite, pyromorphite, hemimorphite, smithsonite, and sphalerite was concentrated by … Read more
The work covered in this report is a continuation of an earlier feasibility study by the Federal Bureau of Mines and points out improvements in the skull-melting method for casting reactive metals such as titanium, zirconium, and hafnium. Machined graphite molds with laminated sections can be reused many times. Large tube sections can be produced … Read more
More than 95 percent of the total tin in Bolivian mine-run ores can be volatilized and recovered as tin chlorides at temperatures ranging from 520° to 565° C. Equally high percentage recoveries of tin can be obtained from low-grade Bolivian concentrates at temperatures of 565° to 600° C. Minus 35-mesh ores and concentrates can be … Read more
The crushing of chestnut-size (1-5/8 by 13/16 inch) Pennsylvania anthracite in four commercial crushers (impact, jaw crusher, hammer mill, and gyratory types) was studied by the Bureau of Mines to determine which could produce the largest proportions of buckwheat Nos. 1 and 2 sizes (9/16 by 3/16 inch). Single pass dry and wet crushing techniques … Read more