Research into platinum-based tailings derived from a recovery boiler of the production of nitric acid and its preparation for the extraction of platinum group metals

Abstract

The paper deals with the characterization of platinum-based tailings derived from a recovery boiler of the production of nitric acid. The composition of the tailings was determined and the calcination process was investigated in order to improve the extraction of platinum group metals (PGM) into concentrate. According to the results of the research, the size of the majority (81.6%) of particles of the tailings is less than 0.1 mm. The results of X-ray diffraction and laser mass-spectral analyses indicate that the tailings contain 7.82 wt.% of platinum, 1.56 wt.% of palladium and 0.09 wt.% of rhodium. It also contains carbon and ferromagnetic iron. It is shown that magnetic separation used as a preparatory stage allows extracting about 20 wt.% of ferromagnetic iron from platinum-based tailings of nitric acid production. The influence of various technological parameters on calcination of PGM tailings from recovery boiler was investigated in the temperature range of 1023 to 1173 K. The largest mass loss of the tailings is up to 9 wt.% at 1123 K during 60 min of calcination. X-ray structural analysis of calcinated samples of PMG tailings from recovery boiler of nitric acid production revealed that palladium oxide decomposes and carbon is burned out in the course of calcination. The mass loss of carbon is 1.34 wt.% during 60 min of the heat treatment. It was found out that calcination leads to cracking of PGM which improves extracting process of platinum-based tailings of nitric acid production.В даній роботі досліджено вміст платиновмісного шламу, який зібраний з котла-утилізатора виробництва нітратної кислоти та процес його випалу з метою удосконалення технології вилучення металів платинової групи у концентрат.