Study On The Distribution Of Elements In The Process Of Complex Tin Concentrate Reduction Melting Process

The grade of tin ore was decreasing and the composition was becoming increasingly complex, the concomitant impurity elements such as Fe, Pb, Cu, Si, Ca, Mg, Al, Ag, Sb, Bi, Zn and As inevitably entered into the tin smelting process. This could greatly affect the reduction smelting process of tin concentrate. In order to control the impurities content in the intermediate product and form into theoretical basis of clean and efficient generation process of tin, the regularity of elements distributions should be investigated.Thermodynamics analysis indicated that, in the reduction smelting process of tin concentrate, one part of the existence of Sn and Fe formed into metal phase and entered into crude tin, and another part formed into oxide and entered into in the slag. Pb, Cu, Ag, Sb, Bi entered into crude tin as metal phase. Si, Ca, Mg, Al existed as oxide phase in the slag. Zn and As became to gas and volatilized with the smoke. Theoretical research of tin smelting slag showed that, ternary slag of FeO-SiO2-CaO should be chosed, and the composition range should be controlled as follow: SiO232%～46%, FeO35%～55%and CaO5%～20%. Through the research of analyzing test methods of the tin ore concentrate and its smelting material, an exact and efficient analysis method in the reduction smelting process of tin ore concentrate was established.The tentative exploration showed that, for reducing per100g tin ore concentrate,8g of coke,2.16%of quartz sand and4.29g of limestone should be added into. In the condition of temperature was1325℃and holding time was2h, the grade of crude tin was higher, which could reach to more than75%. The effect of temperature and holding time on the reduction smelting process of complex tin concentrate was investigated. The scanning electron microscope was used for observing the surface characteristics of crude tin, as a product of the experiment. The results showed that, the rise of temperature made the content of Fe in crude tin increased and distribution of Fe in crude tin more centralized. What’s more, the extension of holding time made the distribution of Fe more uniform in crude tin. The response surface method (RSM) was used for model fitting the production of crude tin and slag as well as the distribution rate of the13elements such as Sn, Fe, Pb and Cu in crude tin and slag respectively. The regression equation of the effect of temperature and holding time on the distribution rate was obtained, which was the regularity of elements distributions: For example, the distribution rate of Fe in crude tin was YFetin=-146156+317.74A+1808.67B-2.76AB-0.23A2+41.98B2+0.001A2B-0.044AB2+0.000056A3+2.23B3, the distribution rate of Fe in slag was156+317.74A+1808.67B-2.76AB-0.23A2+41.98B2+0.0011A2B-0.044AB2+0.000056A3+2.23B3and so on.