A new extraction procedure for simultaneous quantitative determination of water-soluble metals in reaction products of clays and inorganic salts

Kaolin, a possible source of Al, may be reacted with inorganic acids or salts to form different Al salts that can be further processed to prepare metallic Al. Although the reaction of kaolin and acid in aqueous solution can be monitored by chemical analysis of Al, the Al salts must be extracted from any unreacted kaolinite. Also, the lixiviation of Ti or Fe species present in kaolin should be monitored. A simple extraction procedure is reported to determine, quickly and quantitatively, water-soluble Al, Ti and Fe metals present in products of reaction of kaolin (85 wt.% kaolinite, 12 wt.% mica, 2 wt.% feldspar, 1 wt.% quartz) with inorganic salts, such as sodium hydrogensulfate, using conventional glassware for the glass reaction tubes. Optimum results are obtained with 250 mL glass reaction tubes. The best operating conditions found for this piece of equipment are: (1) sample weight of 0.05 g, (2) lixiviation time of 1 h, and (3) lixiviating agent, 50 mL of an aqueous solution of pH = 1 H2SO4 at its boiling point. Comparisons are made with soxhlet extraction and beaker and magnetic stirring methods.