Siberian Federal University

Data on the influence of the nature of mineral acids on the indicators of lanthanum phosphate opening by a new method – hydrothermal acid dissolution of lanthanum phosphate at a temperature of 180–220 °C in the presence of iron(3+) oxides (hydroxides) have been obtained. It has been established that from the studied acids – nitric, hydrochloric and sulfuric, effective extraction of lanthanides with deep dephosphorization of solutions is achieved only for nitric acid. In this system, the extraction of lanthanum into solution is 97–98 %, and the phosphorus content is reduced to 10 mg/L or less due to the formation of stable iron(3+) hydroxyphosphate – giniite. For hydrochloric acid, a preferential transition to iron(3+) solution is observed due to its complexation with chloride ions, and the extraction rates of lanthanum into the solution did not exceed 5 %. The content of phosphorus in the solution is also significantly higher than for nitric acid. When using sulfuric acid, sparingly soluble hydroxysulfates are formed. The phase of gyniite formation is not observed, and the extraction of lanthanum into solution does not exceed 10 % for a sulfuric acid concentration of 4 mol/L