Selection of crud processing methods with complex extraction of osmium and other valuable components

At present, the available data on the behavior of osmium in the course of extraction of rhenium from washing sulfuric acid used in the production of copper are extremely limited and contradictory. In this connection, the investigation of its behavior in some processes of processing of osmium-containing raw materials and its purposeful accumulation in cruds prove to be quite urgent. We formulate possible causes of formation of the interphase suspensions (in what follows, referred to as cruds) in the technology of rhenium extraction. We also present the results of investigations aimed at the development of physical and chemical foundations of the processes of getting osmium concentrates. A technology of crud processing based on the processes of repulping, sintering, leaching, and extraction of rhenium is proposed. The optimal conditions for the main operations are studied and selected: for repulping, these are S:L = 1:5 with stirring for 1 h at room temperature; for sintering, the consumption of CaO is 200–300% (1:3) relative to the weight of the sediment, its temperature is 300 °C, and the duration of sintering is 2 h, and, for leaching of the cake, S:L=1:4 at a temperature of 20–40 °C for 1 h. We propose a combined method for the extraction of osmium into a concentrate. This enables us to concentrate osmium in the cake and then use this cake to obtain metallic osmium. In this case, a significant part of rhenium (93%) remains in the solution and is then sent to the operation of getting ammonium perrhenate.