Siberian Federal University

The implementation of autoclave hydrometallurgical technologies for processing platinum group metal feedstocks in hydrochloric acid media is hindered by the high corrosive aggressiveness of the working solutions, typically hydrochloric or nitric acids, at elevated temperatures and pressures. In this study, the dissolution behavior of titanium and platinum plates, as well as synthesized platinum black, was investigated in hydrochloric acid solutions with hydrogen peroxide added as a precursor to gaseous oxygen. The experiments were conducted in laboratory-scale quartz autoclaves at temperatures ranging from 90 to 200 °C. Under autoclave conditions with an applied excess oxygen pressure, titanium exhibits high stability at HCl concentrations ≤ 3 M and temperatures ≤ 160 °C, demonstrating a mass loss of less than 0.1 % over 360 minutes. It was found that the presence of platinum ions in solution inhibits titanium corrosion, which opens up prospects for its application as a structural material in PGM refining equipment. Under autoclave conditions, platinum dissolution reaches 20 % within 30 minutes at 100 °C in a 6 M HCl solution containing H2O2, while at 160 °C, over 90 % of the platinum dissolves within the same time period. For platinum black, a 30 % dissolution extent is achieved within 30 minutes at 110 °C in a 3 M hydrochloric acid solution under oxidizing conditions