Uranium-Bearing Cast Stone Matrices

This work examines cast stone matrices (CSM) fabricated by comelting of basalt with both uranium-bearing perlite (M150 grade) and U₃O₈ at a temperature of 1623 K in air for 5 h. As a result of comelting of basalt with uranium-free M150 grade perlite, matrices are obtained containing glass and spinel as the major phases. When basalt is comelted with uranium-bearing perlite (M150 grade) CSMs are formed, the major phases of which are two Cr-spinels of different compositions, uranium-bearing glass, and dendritic aluminosilicate crystals. In the case of fusion of basalt and U₃O₈ taken in the initial weight ratio of 1 : 1, CSM is generated as the major phases containing UO₃, CaU₃O₁₀, (Al,Cr,Fe)₂U₂O₉, plagioclase, and uranium-bearing glass. The leaching rate of uranium from a basalt melt with uranium-bearing perlite (M150 grade, ~7.2 wt % U) and that of CSM made by comelting of basalt with U₃O₈, (~42.5 wt % U) after 28 days contact with water at 298 K was investigated.