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[en] The United States depends entirely on foreign sources for the critical material, chromium, making it very vulnerable to supply disruptions. This vulnerability results because chromium is essential for the fabrication of corrosion-resisting steels and high-temperature, oxidation-resisting alloys in applications that are vital to the nation's technological well-being; because no substitutes are known for these materials in those applications; and because the known, substantial deposits of chromite ore are only in a few geographical locations that could become inaccessible to the United States as a result of political actions. The effectiveness of programs such as stockpiling, conservation, and research and development for substitutes to reduce the impact of disruption of imports of chromite and ferrochromium are discussed. Alternatives for decreasing chromium consumption also are identified for chromium-containing materials in the areas of design, processing, and substitution
[en] Experiments with Na131I in liquid phase were carried out at two feed rates to obtain the residence time distributions and to verify the invariance of the dimensionless residence time distribution in a rod mill grinding chromium ore. Based on the data the size-mass balance method was used to construct a simplified model assuming that the breakage and selection functions satisfy the standard hypothesis B(x,y)S(y)=axα. It was proved by simulation of a known size distribution that the model really works over practical operating ranges. Knowing the fact that the size interval of ground chromium ore between 0.08 and 1.2 mm gave the best concentration results on wet shaking tables, the model was used to predict the weight per cent of the desired size range in the ground ore versus various operating conditions. Recommendations are also given. (author) 14 refs. 6 figs
[en] Differential thermal analysis is applied to study chromium ore, aluminosilicate fluxes, and mixtures of these materials. The dependence of the thermal transformations in the fines of the ore from the Donskoy Ore Mining and Processing Plant on the content and type of added fluxes is estimated. An analysis of the experimental results is supplemented with X-ray diffraction analysis of the sinters of chromium ore with a high flux (clay, microsilica) content (up to 10%), which corresponds to the end of softening of the mixtures.
[en] The difficult economic circumstances with which almost the whole world had to contend, brought serious financial crisis in many countries. South Africa also had its own share of serious problems. Despite this situation, Transvaal Consolidated Land and Exploration Company, Limited, showed on increase in earnings of 24 per cent per share. The reason for this lies mainly in two areas. Firstly the company acquired the mining related business of Rand Mines, Limited. Included in the acquisition was a partfolio of shares mainly in the company's associated gold and uranium mining companies and additional shares in its listed coal mining subsidiaries. Secondly, the average gold price realised by producers in rand terms, was considerably higher than in the previous year. Consolidated profit attributable to members increased by 52 per cent to R82,6 million