Composition and characteristics of slags from continuous converting of copper matte and concentrate

The investigation results of the slags obtained in a newly developed process of continuous converting to blister copper of a mixture of nickel-containing copper matte and concentrates are presented. X-ray, SEM, EPMA and other methods were used to obtain the results. The slags are within the FeO-Fe2O3-SiO2-CaO-Al2O3-Cu2O-NiO system and are found to be prone to saturate trevorite (NiFe2O4)-based spinels whose content depends significantly on the consumption of fluxing components and on the changes of total concentration in the slag of (Fe+Ni) and (SiO2+CaO). It is found that these slags are homogeneous in the range of SiO2/CaO ratios from 0 center dot 25 to 1 center dot 0 under the condition that (Fe+Ni) total concentration in slag are 25-27%. It is shown that the dependence of the liquidus temperature on the SiO2/CaO ratio is characterised by a minimum at 1325 degrees C with SiO2/CaO of 2. It is determined that the increase in the slag liquidus temperature reaches the maximum (1330 degrees C) with copper content in matte of 60%. It is demonstrated that copper in these slags is mainly present in a soluble form and that copper dissolved in a silicate melt is present both in association with oxygen (oxide solubility) and outside this association (metallic solubility). Based on the obtained results, several guiding, practical industrial conclusions are drawn for a successful operation of a new continuous process.