A process for separation of silica from siliceous magnesian limestones

Whereas high-grade dolomites and limestones find extensive use in the refractory and steel industries, high-silica dolomitic limestones are of little use and can cause disposal problems as mining rejects. The removal of silica and magnesia to certain specified limits can make them suitable for cement manufacture. Magnesia can be removed by a carbonation process after semi-calcination of dolomite but the removal of a large amount of silica prior to MgO separation, by the flotation process alone, is uneconomical. Here the results are presented of the investigations of hydrocyclone separation of silica from one such type of mining rejects. The results show that after grinding the feed material to suitable levels of liberation of quartz and carbonate grains, two cycles of operation in a 4′′ hydrocyclone, can recover about 45% of the limestone feed material with a lime/silica ratio adequate for cement manufacture.     

Statistical method for distance determination of a stellar group

In this paper, we developed statistical method for distance determination of a stellar group. The method depends on the assumption that, the stars scatter around a mean magnitude in a Gaussian distribution. The mean apparent magnitude of the stars is then expressed in terms of the frequency function of the apparent magnitudes, so as to correct for observational incompleteness at the faint end. The problem reduces to the solution of a highly transcendental equation for a given apparent magnitude parameter α. Computational algorithm of the method is illustrated and the numerical solutions of the basic equation are given for some values of α .