Promote Alumina Leaching through Re-Pelleting: Effects of Directional Coating of Calcite on Silicate Grains

Abstract

Abstract:The contents of Fe and SiO 2 in ferric bauxite are much higher than that in regular bauxite, and the leaching yield of Al 2 O 3 from ferric bauxite cannot reach the general level of ordinary ores, even under optimal conditions. This paper introduces a pretreatment method to enhance sintering before leaching. First, mixing followed by grinding was found to be more efficient than grinding followed by mixing as a pretreatment method by forming a directional coating structure of CaCO 3 on the SiO 2 surface. Second, leaching yields increased grinding fineness because CaCO 3 grain uniformity could be improved with the latter method. Finally, the leaching yields were increased by pulp consistency under certain conditions, as evidenced by improvements in CaCO 3 uniformity, bulk density, and Al 2 O 3 grain size, which parameters were beneficial to enhance leaching. The leaching yield of Al 2 O 3 was increased from 75.2% to 87.15% by using the proposed mixing-grinding method with the leaching agent of water.