Preparation of rhodium concentrate from gold cementate

Abstract

This article describes studies on improving reprocessing technology gold production cementate (GPC) formed in refining section of chemical metallurgical shop at JSC Uralelektromed, in order to increase the extraction rate of targeted metals into marketable products, diversification of production, achievement of economic effect due to increasing content of precious metals (PM) in individual concentrates. The optimization of GPC reprocessing technology includes intensification of leaching of initial material and filtration of produced pulp, in order to increase the extraction of gold and platinum group metals (PGM) into solution and decrease the circulated PM. This would allow individual products (crude PM) to be obtained with minimum material loss and labor consumption. It is possible to increase rhodium content in concentrate and to reduce its circulation by preliminary oxidating annealing at the temperature above 500 °C. At this temperature hardly soluble trioxide Rh2O3 is formed on rhodium surface, insoluble in aqua regia, thus allowing it to deposit in the form of individual product. The influence of temperature and composition of gaseous phase was established upon oxidizing annealing of initial raw stuff (t = 500÷750 °C) on the composition of rhodium trioxide concentrate (15÷45 % Rh2O3). Reprocessing flowchart of gold production cementate was developed and tested on commercial scale, allowing for the simultaneous production of several products: deposited gold (Au ≥ 98 %), deposited silver (Ag ≥ 98 %), PGM concentrate (Pt ≥ 45 % and Pd ≥ 15 %), rhodium concentrate (Rh = 15÷45 %).