STUDIES OF HYDROCHLORIC ACID DECOMPOSITION OF CLAY SLURRIES OF SILICEOUS-TITANIUM ORES

The chemical and mineral compositions of gray-colored and red-colored slurries formed during the disintegration of silicon-titanium ores of the Pyzhemskoye deposit are considered, and the results of a study on their hydrochloric acid leaching of 20% HCl in the temperature range of 40-200°С are presented. It is shown that an increase in the leaching temperature leads to an increase in the degree of opening of sludge, which is associated with the decomposition of a number of mineral phases. At temperatures of 40-100°С, the decomposition of siderite and goethite proceeds. The decomposition of clay minerals develops at a temperature of 90° C and above. The process is accompanied by the release of gel-like SiO₂. Under autoclave conditions, the decomposition of pseudorutyl, as well as monazite and xenotime occurs simultaneously with the transfer to a solution of cerium, neodymium and yttrium. Complete decomposition of REM minerals is achieved at a temperature of 180°С. The non-decomposable solid residue is represented by rutile, quartz, amorphous SiO₂ and zircon.