<報文>黒鉱系銅精鉱の溶錬産出物に関する研究(第1報) : 銅スラグの組織について

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In the process of copper smelting the behaviors of magnetite and valuable metals have been the matter of interest of metallurgists, but there remain many problems to be clarified. The smelting products from a flash smelting furnace at the Kosaka Smelter are especially complicated, because the copper concentrate produced from "black ore" contains considerable amounts of lead and zinc. The present study covers the results of investigation of microstructure of slags obtained from the flash smelting furnace and converter, using microscope and electron probe micro analyzer. When the molten slag taken by an iron spoon is solidified, the middle part of this sample was cooled slowly, on the other hand the edge of the sample was chilled into glassy state. Microstructure of rapidly cooled converter slag is illustrated in Photo 1. The composition of glassy part of the sample derived by EPMA measurements is shown in the last line in Table 1,showing fairly good agreement with the values shown in the first line which were determined by chemical analysis. Spherical crystallite in Photo 1 is suspended white metal and white angular crystallite is magnetite. Effects of cooling rate on the structure of matrix are suggested by Fig. 1 and Photo 1. It is recognized from Fig. 1 that the behavior of copper in converter slag is well accompanied by that of sulfur. Photo. 2 shows the microstructure of slowly cooled converter slag. Considering this together with the characteristic X-ray images given in Photo. 3,the following five crystallites are recognized. The analytical results by EPMA are given in Table 1. i) White angular crystallite-magnetite ; ii) Grey large crystallite-fayalite ; iii) Dark glassy part-high in silica, low in iron ; iv) Large light spherical particles-suspended white metal ; v) Small spherical particles consisting of Cu_2S and PbS. In the crystallites of magnetite and fayalite, some part of iron is substituted by zinc. Also in the dark glassy part, considerable amounts of zinc, lead, lime and alumina are contained. The flash smelting furnace slag was sampled from the settling furnace by the iron spoon. Analytical values obtained by EPMA for rapidly cooled glassy part are shown in the last line in Table 2,illustrating good agreement with those obtained by chemical analysis. Fig. 2 illustrates the effect of cooling rate on crystallization, and suggests that sulfur in matte smelting stag has intimate relation with zinc. Photo. 4 shows the microstructure of slowly cooled slag passing through the flash smelting and settling furnaces. In comparison with that of converter slag, various small crystallites are found jumbled, but the following phases are recognized : 1) Angular white crystallite-magnetite ; 2) Grey large crystallite-fayalite ; 3) Small black glassy crystallite ; 4) Yellow sulfide particles in irregular shape-Cu_2S-FeS ; 5) Light greyish vague peripheral crystallite-ZnS-FeS ; 6) Suspended composite sulfide particles-not detectable by Photo. 4. Analytical values obtained by EPMA for these crystallites are given in Table 2. Yellow sulfide particles as stated 4) above seem to be the phase separating out from molten slag during the solidification. It should be noticed that considerable part of zinc in slag is likely to be existing in sulfide form. In comparison with the slags obtained from other smelters, the structure of matte smelting slag of the Kosaka Smelter looks to be indigestible, and seems to be not convenient for lowering the slag loss and recovery of valuables by flotation. The reason may be ascribed to the existence of impurities, especially to the behavior of zinc.
1973-03-30

<報文>黒鉱系銅精鉱の溶錬産出物に関する研究(第1報) : 銅スラグの組織について

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