Use of Commercial Limestone and Other Commercially Available Raw Materials in the Lime-Soda Sinter Process for the Extraction of Alumina from a sub-Bituminous Western Coal Fly Ash

摘要

The study of commercial limestone in the Lime-Soda Sinter process has shown that high alumina recoveries are possible using high grade limestones. High recovery sinter compositions using limestone appear to be in the same region as those performed with calcium carbonate reagent, and thus the results demonstrate that high grade limestone can be used as a substitute. Magnesium oxide is a relatively inert material in the sinter reactions. Dolomitic limestones can be used but only the calcium carbonate portion of the rock is reactive. Potassium carbonate is reactive and can replace soda ash; therefore, it is expected that credit can be taken for both Na sub 2 O and K sub 2 O contained in fly ashes, limestones, kiln dusts, etc., to decrease the amount of soda ash which must be added to sinter mixtures. Sodium chloride cannot substitute for sodium carbonate; the chloride ion is probably detrimental in the sinter reaction. Synthetic Trona was shown to be an excellent substitute for sodium carbonate. Kiln dust can be used as a suitable lime substitute. The particle size of the limestone is an important factor in the investigation of the maximum yield of aluminum. (ERA citation 07:020781)