| Abstrakt: |
The pyrometallurgical technology of producing germanium concentrates from the raw materials taken from brown coal deposits (coal, mudstones, siltstones) is accompanied by the formation of silicate slag melts, which concentrate the mineral component of the raw materials (reaching 60% wt %). Obviously, the energy indicators of technology are substantially determined by the physicochemical properties of slag melts. These include electrical conductivity λ, which reflects the structure of silicate melts. The compositions of the slags from processing carbonaceous raw materials differ significantly from nonferrous and ferrous metallurgy slags: they contain high contents of SiO2 (up to 50–55%), Al2O3 (up to 20–22%), and K2O and Na2O (up to 5–6%). In addition, noticeable amounts of sulfide sulfur (up to 3%) and microimpurities of nonferrous metals and rare elements (up to 5%) are present in the slags. The differences between the compositions of the slag melts of germanium production and the slags of the general metallurgy affect their properties and require special-purpose studies. Industrial samples of cyclone melting and electric melting slags are studied. Semisynthetic samples prepared from industrial samples by adding SiO2 and CaO are used to determine the influence of the slag composition on λ. A standard compensation method is used to measure the resistance of the melt with an ac bridge at a frequency of 3.5 kHz. The cell consists of a melt in an alundum crucible with immersed molybdenum electrodes. The melt temperature range is 1100–1550°C. The values of λ of the melts are found to be in the range from 0.01 to 0.30 S/cm and to depend substantially on the basicity (i.e., the ratio of the sum of the CaO and MgO contents to SiO2) and the Al2O3 content. The temperature dependences of λ are shown to be exponential. In the general case, λ of the melts under study is much higher than that characteristic of, e.g., blast-furnace melting at the same basicity. The results obtained are useful for predicting the structure of melts. [ABSTRACT FROM AUTHOR] |
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