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The thermal conductivity of various copper matte and fayalite slag was measured using laser flash analysis, a non-steady state measurement method. Industrial matte and slag samples were taken in such a way that their composition represented typical process conditions. Thermal conductivities for solid copper matte (average 64% Cu) were found to be from 1.2 W m-1K-1 at 300°C to 2.1 W m-1K-1 at 900°C. Because arsenic is one of the most important impurities in copper matte, its effect on thermal conductivity was investigated with As-doped matte samples up to 0.59% As. The results showed substantially lower thermal conductivity, between 0.5 W m-1K-1 and 1.3 W m-1K-1 at 300-900°C with low As matte, behavior that is analogous to that of a semiconductor. The data obtained showed that the thermal conductivity of copper matte increased linearly with temperature, but the gradient was small. The thermal conductivity of slags was found to be between 1.6 W m-1K-1 and 1.9 W m-1K-1, values that are consistent with earlier studies.
INTRODUCTION
Copper flash smelting is a method used to process sulfidic copper raw materials (typically concentrates with 20-30% Cu) into a molten copper-rich matte and, in a few cases, blister copper. At the same time, an impurity-rich and separable slag of molten oxides is generated. When smelting to matte, the copper content of matte (known as matte grade) optimally varies from 55% to 68%. The smelting temperature is high, i.e., 1250-1300°C, thus requiring a good cooling system for the furnace. Although current systems developed for the flash furnace can already provide efficient cooling, the future of digitalization requires more process data, such as thermal conductivity.1
In particular, thermal conductivity data for matte and slag can provide more information about realtime furnace temperature.1 If these data are applied, it could result in prolonged refractory lining, increased production time, and improved safety of the working environment.
As a result of the increased throughput and capacity of flash smelting furnaces, the thermal load on their refractory linings has increased and new cooling systems have been designed for further protection. The enhanced cooling will create a freeze lining on the refractory or cooling plate...