In accordance with a program for developing new materials required for emerging technologies, an investigation was undertaken to determine the properties of dispersion-strengthened copper. The copper contained either alumina or yttria as a dispersoid and was prepared by coprecipitation-a potential method for commercial production. Although the coprecipitation method had been used previously to prepare dispersion-strengthened … Read more
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 … Read more
The use of controlled steel silicon content or the application of borax coatings showed promise in preventing molten copper from forming on the surface of steels containing up to 1 pct Cu when these steels were heated to 2,370° F (1,300° C) , a common temperature for rolling. By preventing copper formation during heating, surface … Read more
The Bureau of Mines research programs are partly directed to developing safety guidelines for the reduction of fires and explosions in industries that produce, transport, or utilize mineral fuels and their products. As a result of a request by the Department of Transportation, the Bureau is evaluating test methods for classifying hazardous materials and developing … Read more
Electrostatic separation is used when froth flotation fails, such as with oxidized ores, or where there are similarities in response with magnetic and gravitational methods, or when the use of water is to be avoided. Theoretically, for fine-size particles the electric field has an advantage over the magnetic field in that the viscosity-limited particle velocity … Read more
In recent years, more than 99 percent of the domestic mica produced has been scrap and flake mica (mica which does not meet specifications for sheet mica and which is used for producing fine-ground mica). There has been a continued increase in mica production for several years. The 1969 production of scrap and flake mica … Read more
The Calico mining district in California contains extensive deposits of low-grade silver ore. The deposits cover a large area and constitute an important silver reserve if difficult concentration problems can be solved. The deposits also contain barite, which, if recovered as a byproduct during treatment of the silver ores, might contribute to the economic returns … Read more
The profitable operation of a coal preparation plant under today’s stringent product standards and ever-rising labor, material, energy, and equipment costs requires that the preparation engineer continually strive for maximum recovery of salable coal. Good performance data are a prerequisite to the design of a new plant or to the expansion of existing facilities, and … Read more
One of the goals is to minimize the requirements for critical and strategic mineral commodities through conservation and substitution. As a part of this effort, the Bureau conducted research to develop molybdenum as a potential substitute for alloys containing the critical and strategic metals nickel, chromium, or cobalt. As expressed in Iron Age, this Nation … Read more
As a part of the Bureau of Mines research program to develop new mining methods for underground bedded deposits, a rock splitting tool capable of applying both radial and axial forces is being investigated as a primary excavation tool. From the long-known hammer-driven wedge and ice expansion methods of propagating existing cracks in rock, mechanical … Read more