Mössbauer and X-ray Diffraction Spectroscopy of High-Iron Bauxites from Kazakhstan

The bauxite ores of Kazakhstan were analyzed using Mössbauer spectroscopy, X-ray diffraction and an X-ray fluorescence analysis. Experimental data on the structural-phase composition of bauxites were obtained, and the features of the iron-bearing minerals within them were revealed. The studied bauxites were high in iron. The magnetic part of bauxite was mainly represented by aluminohematite with a concentration of C_Al = 3.34-5.73 at.%, alongside goethite in small amounts. The predominant phase in the bauxite samples was the alumina-bearing mineral gibbsite with a well-crystallized monoclinic lattice. The main siliceous mineral of bauxite is kaolinite, which showed distorted octahedral positions in a number of samples. Siderite amounts were found to vary in the range of 0-15 at.% in the present iron-bearing minerals. Ilmenite was also present in the bauxite of some deposits; anatase was found in all bauxites and was the final product of ilmenite decomposition in the weathering crust.