Study On New Process Of Antimony Sulfide Concentrate To Produce Needleantimony With Low-temperature And Sulfur-fixing Smelting In Na₂Co₃-KCl Molten Salt System

Because the present pyrometallurgical process of antimony sulfide concentrate has the problems with high energy consumption and the atmospheric emissions of low-concentration sulfur dioxide, a new process of antimony sulfide concentrate to produce needleantimony with low-temperature and sulfur-fixing smelting was proposed. Using the stibnite as raw material, the pulverized coal as reductant, zinc oxide as sulfur fixing agent, and sodium carbonate etc as fused salt, a process of antimony sulfide concentrate to produce needleantimony with low-temperature and sulfur-fixing smelting was carried.The thermodynamics firstly was studied in the Sb2S3-ZnO-Na2CO3-KCl system through calculation and analysis. The result shows that the process of antimony sulfide concentrate to produce needleantimony with low-temperature and sulfur-fixing smelting is feasible in the ZnO-Na2CO3-KCl system under the temperature of700-1000K. The products include antimony with lead, copper, arsenic etc. and fused salt with sodium carbonate, potassium chloride etc. and slag with zinc oxide, zinc sulfide, gangue, etc. The result of thermodynamics analysis revealed that the process is realized potentially by three ways. One way is that Sb2S3is firstly resoved, and then is ruducted and sulfur-fixed. Another way is that Sb2S3is firstly ruducted, and then sulfur-fixed. The final way is that sodium carbonate is used as reactiong medium.Based on above-mentioned process fundamental study, the condition tests and comprehensive tests of antimony sulfide concentrate to produce needleantimony with low-temperature and sulfur-fixing smelting were carried. The best optimum conditions for smelting are temperature850℃(1123K), smelting time two hours, liquid-solid ratio4-5(mass ratio),WNa2CO3/WKCl4(mass ratio), quality excessive coefficient of ZnO1.2times, and quality excessive coefficient of pulverized coal1.5-2.0times. The direct recovery rate of Sb was91.3%, and the grade of Sb was92.4%, sulfur fixing in solid slag was74%as the form of ZnS, sulfur fixing in fused salt was21.7%, and the total sulfur fixing was95.7%. Finally the simulation test of melting was carried out between gangue and fused salt. It is found that both calcium carbonate and magnesium oxide will not react with sodium carbonate, aluminium oxide is able to impact into partial aluminum acid sodium with sodium carbonate, and silica is able to impact into sodium silicate with Sodium carbonate.The process of antimony sulfide concentrate to produce needleantimony with low-temperature and sulfur-fixing smelting not only can save energy consumption significantly, but also can considerably reduce the atmospheric emissions of low-concentration sulfur dioxide.