| The slag from tin-smelting in electric arc furnace can produce pollution of nonferrous smelting process in electric arc furnace smelting of tin. The average production of 1 ton tin can produce about 1.5 to 2.5 ton smelting slag and the slag also has great value. Because of the complex recovery steps and low single recycling economic value, the present study of smelting slag recycling in our country did not have certain industrial application. At the same time, a large number of smelting slag was used as a building material handling, landfill and so on. Stacking a large number of Smelting slag make a serious threat to environmental pollution. Therefore, recovery of smelting slag has great importance in resource and economic.As a circumstance, we are focusing on producing metal tin, calcium sulfate whisker, micron barium sulfate and nano-silicon from tin smelting slag, we selects hydrochloric acid as leaching solvent. The raw material slag from tin-smelting in electric arc furnace of one nonferrous enterprise in Zhejiang Province can be enriched efficiently by wet leaching using hydrochloric acid. Using hydrochloric acid leaching can remove Si, Ca, Ba and other components to the liquid and make of tin component stay in the slag, the impurity components and tin component can be well separated. After hydrochloric acid leaching reaction, take the components from the liquid to recovery calcium sulfate whisker, nano-silica, barium sulfate and other products. Use strong acid to leaching the rich tin slag, then can get the acid liquid rich of tin. After leaching, the active metal will be used to replace impurity component antimony and target component tin respectively. The whole process can achieve closed-circuit circulation of reaction and also can make high utilization rate of raw materials.Firstly, this paper uses hydrochloric acid leaching process to remove impurity. Take tin-smelting waste slag as the raw material, the raw material was mixed with water suspension. The factors such as the liquid-solid ratio, reaction temperature, stirring speed, the acidity of hydrochloric acid affect the removal rate of impurities. Tin content from the slag enriched from 2 % to 14.96 %. The appropriately technological conditions of acid leaching were: the concentration of hydrochloric acid was 6 mol/ L, the liquid-solid ratio was 25:1, the reaction temperature was 40 ℃, the stirring speed of was 250 r/min.Secondly, leaching the rich tin slag with hydrochloric acid could get the acid leaching solution of tin and antimony. Using zinc and tin containing waste powder for replacement of antimony in acid leaching solution, then got the optimum process of antimony removal. After antimony removal, using metal zinc replacement technology to recovery tin in the acid leaching solution, tin purity rate could reach to 97.35 %.The impurity components also recovered after hydrochloric acid leaching reaction. And barium sulfate, calcium sulfate whisker and nano-silica could get. The appropriately technological conditions of micron barium sulfate making were: reaction temperature was 10~20 ℃, the stirring speed was 400 r/min, the concentration of sulfuric acid was 40 wt%. The appropriately technological conditions of calcium sulfate whisker making were: reaction temperature was 60 ℃, the concentration of sulfuric acid was 50 wt%, the stirring speed was 250 r/min, the reaction time was 4 h. Under these conditions the reaction of the whisker length diameter ratio can reach 130. After recovered the Ca, Ba component from the liquid, took the liquid to evaporate to recover the hydrochloric acid. Recover silica from the liquid after the recovery of hydrochloric acid liquid. The appropriately technological conditions of silica making were: took PEG 2000 as surface active agent, the reaction temperature was 60~90 ℃, the stirring speed was 400 r/min. |
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