Separation, settling and flow phenomena in electric matte smelting of Cu-Ni concentrates

摘要

The flow of slag and settling of matte in slag resistance electric furnaces are discussed in conjunction with furnace geometries, stirring action of the electrodes, buoyancy and electromagnetic effects, all of which obviously affect matte-slag separation and metal losses to the slag. The effect of change in slag composition upon such losses and the relationship between slag composition and slag-matte separation are also discussed on the basis of the laboratory tests conducted at 140CTC. The relationship between slag composition and matte-slag separation was found to depend primarily on the basicity ratio and the FeO content of the slag. The rectangular electric furnace was regarded as a channel reactor. The flow is affected both by buoyancy and by electromagnetic forces, however, the effect of the latter is minimal. The flow velocity is made up of two components; (i) that developed by the action of the electrodes, and (ii) the bulk velocity determined by the smelting rate and the volume of the reactor. Slag samples were taken from various depths of the molten bath and were analyzed microscopically to determine the size and distribution of matte prills which would lead to the better understanding of the separation and settling behavior. The rectangular 6-in-line electrode furnace was also considered as made up of 6 separate reactors all of which are acting as continuously stirred settling/separation reactors connected in series. This attempt has led to the conclusion that, under the conditions of the electric furnace, the most effective length of the settler would be between about 13 and 86 percent of its total length.