A research program was conducted to improve processing technology for extracting alumina from nonbauxitic. The success of this program had provided the technology necessary for producing an adequate supply of high-grade alumina from domestic sources, thus meeting national economic and strategic needs relative to aluminum production. The hydrochloric acid process for recovering alumina from low-grade ores is one … Read more
This paper presents a development of thickening theory which provides a reliable and easy-to-use method for determining the size of continuous thickeners from batch settling tests. It also offers a description of thickener operation performance based upon the proposed method. Thickener Operation Figure 13 shows a log-log relationship between underflow concentration and unit area at … Read more
Increasing capacity of bulk material handling systems creates difficult problems for accurate in-line material weight measurements. At the same time increasing system complexity and growing user demands call for more measurements. Precision in-line weight measurements for bulk materials are usually accomplished by application of conveyor belt scales. Belt scale accuracies listed by scale vendors are … Read more
The crushing plant simulator was utilized to evaluate the influence of major variables on the following responses: plant reduction ratio , weight % of -½ inch material in screen undersize, circulating load ratio and secondary screen efficiency. Variables manipulated were: weight % of +1 inch material in secondary crusher feed (73.3 to 92.9%), secondary crusher … Read more
Currently, most coal mines rely primarily on two methods for controlling dust. The first utilizes large volumes of outside air to ventilate and dilute the dust (and methane gas) to acceptable concentrations. The second method involves water used in various ways, such as water spray systems. Unfortunately, both techniques have limitations. For example, increasing the … Read more
Two of the missions of the Bureau of Mines are to conserve scarce, costly metals and to reduce pollution. In accordance with these missions, the objective of this investigation was to develop a method of recycling spent chromium etching solutions that are now discarded as wastes. Solutions containing hexavalent chromium (as chromic acid or sodium … Read more
Disposal of the salt slag produced during the processing of aluminum dross and scrap is of particular interest to the secondary aluminum industry. Melting of these materials is carried out under a salt flux cover to dissolve the contaminants, mostly aluminum oxide, and to optimize the recovery of aluminum metal. Typically, dross and low-grade scrap … Read more
This report describes possible material application as oxygen electrode catalysts. The ultimate objective was to assess the potential of abundant, less costly materials as substitutes for platinum, or to increase the efficiency of platinum when used as an oxygen electrocatalyst. Presently, imports account for essentially all of the U.S. requirement for primary platinum metals. The … Read more
Coarse-ore dry sampling of the type found in primary and secondary crushing systems prior to processing, often requires sampling large flow rates containing 2″ to 6″ particles. The cutter width must be adjustable, with the minimum opening being 2½ to 3 times wider than the largest particle (Figure 1). The cutter blades should enter the … Read more
The control of pH in solvent extraction circuits is an old technique but one which has a large potential for future use. The equilibrium position of any reaction which has hydrogen or hydroxide ions, either as products or as reactants, can be controlled by pH adjustment. Several examples of reaction types which are important in … Read more