The reasons for the platinum losses in the metallurgical processing of copper-nickel ores

The extraction of platinum from sulphide copper-nickel ores is a multi-stage process, which includes the melting of the prepared concentrate in electric ore smelting furnaces. In these furnaces, the melt is divided into matte and slag. Platinum is generally concentrated in matte; however, some its part remains in the slag, thus leading to metal losses. In order to reduce platinum losses, the forms of platinum in these phases should be studied. The analysis of possible chemical reactions in ore was carried out using the HSC Chemistry software package. It was experimentally established that platinum in matte is present in the form of intermetallics with Fe and Ni. The Pt-Fe intermetallide is a dispersed needle formation with a length of 20 to 500 μm and a thickness of up to 10 μm. The size effect is revealed: the content of impurities in the PtFe intermetallide increases with decreasing the thickness of needle formations. It was found that matte drops together with the associated Pt, Fe, and Ni intermetallide particles of no more than 5-7 μm in size, were carried into the slag by gas bubbles, which appear due to decomposition of sulphides. The conditions for the rise of a matte drop, together with a bubble in the slag, consist in the fact that the adhesive force of the drop with the bubble and the buoyancy force acting on the bubble must be greater than the gravity of the drop.