Beneficiation of coal pond ash by physical separation techniques.

In this study, investigations to develop a beneficiation process for separating coal pond ash into various products were undertaken. To this end, coal pond ash samples with different particle size ranges were tested in terms of their washability characteristics in a float-and-sink analysis. It was found that coal pond ash was heterogeneous in nature consisting of particles that varied in terms of their size and composition.

Identification of Calcium Sulphoaluminate Formation between Alunite and Limestone.

This study was carried out to identify the conditions of formation of calcium sulphoaluminate (3CaO·3Al(2)O(3)·CaSO(4)) by the sintering of a limestone (CaCO(3)) and alunite [K(2)SO(4)·Al(2)(SO(4))(3)·4Al(OH)(3)] mixture with the following reagents: K(2)SO(4), CaCO(3), Al(OH)(3), CaSO(4)·2H(2)O, and SiO(2). When K(2)SO(4), CaCO(3), Al(OH)(3), CaSO(4)·2H(2)O were mixed in molar ratios of 1:3:6:3 and sintered at 1,200∼1,300 °C, only 3CaO·3Al(2)O(3)·CaSO(4) and calcium langbeinite (2CaSO(4)·K(2)SO(4)) were generated. With an amount of CaO that is less than the stoichiometric molar ratio, 3CaO·3Al(2)O(3)·CaSO(4) was formed and anhydrite (CaSO(4)) did not react and remained behind.