Conventional converting of nickel-bearing copper mattes in horizontal Peirce – Smith converters does not conform with the current environmental regulations. A general global trend includes a transition from conventional batch converting to a continuous converting process producing running slags. The main purpose of the continuous matte converting process is to obtain commercial blister copper that would not require oxidation during further anode refining. To achieve this, rational process parameters should be strictly maintained. The existing method of monitoring the Vanyukov furnace process that is based on the product analysis is a prerequisite but cannot ensure real-time process control. The blister copper obtained through continuous converting differs from the one obtained through the conventional technology in terms of oxygen and nickel concentrations. That’s why its composition should be constantly monitored. The authors looked at how the composition of blister copper obtained through continuous converting of matte tends to change. Samples of blister copper of different compositions were synthesized that are typical of the start-up mode. When the process temperature rises, the required product characteristics can only be obtained if the oxidation potential is higher. This results in a higher concentration of oxygen in blister copper. Mathematical dependencies were derived between the concentrations of nickel and sulphur in the product at various temperatures and the concentration of oxygen. A technique is proposed that enables a real-time monitoring of impurities in blister copper.
The conventional technology of converting copper mattes in horizontal converters has its drawbacks and fails to conform with the current environmental norms and regulations applicable to metallurgical processes. Therefore, it should be replaced with an environmentally sustainable technology. This paper considers the results of a lab and pilot scale study that looked at converting nickel-bearing copper material into raw copper and running nickelbearing slag. It is demonstrated that the continuous converting process can be stable in both three-layer mode (i. e. slag – white matte – copper) and two-layer mode (i. e. slag – copper). With the help of scanning electron microscopy and electron microprobe analysis, it was established that most of copper, nickel and cobalt get wasted in a soluble form. Choice of fluxes produces a significant effect of the process performance. Fluxes were added to maintain the total concentration of SiO2 and CaO in the slag at 32%. At the same time, varying SiO2/CaO ratios were used depending on the operating mode — from pure Fe – Si slag to pure Fe – Ca slag. It is noted that a rising SiO2/CaO ratio leads to a higher recovery of nickel into slag. A pure Fe – Si slag mode is associated with foaming. The results of the lab study were verified through test heats carried out in a pilot Vanyukov furnace. The obtained raw copper has the following composition, wt %: 3.6–4.2 Ni; 0.6–1.2 S; 0.006–0.06 Fe; and it needs to be final converted for better refining.
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