Study On The Law Of Vacuum Volatilization Of Antimony And Lead Sulfide

China is rich in antimony resources, of which Jamesonite is the main complex antimony content. Due to the shortcomings of the existing treatment process, such as incomplete separation of lead-antimony, environmental pollution, energy consumption, long procession, difficult dealing with the waste, Vacuum National Engineering laboratory comes up with the method of vacuum metallurgy processing. It is the use of antimony sulfide, lead sulfide and ferrous sulfide in Jamesonite, which is characterized with low volatilization under the condition of vacuum, to achieve the purpose of separation. Vacuum metallurgical method is equipped with various merits, such as less pollution, time-saving procession, energy conservation, high recovery rate. This paper intends to conduct a research on vacuum evaporation of antimony sulfide, lead sulfide and ferrous sulfide in order to provide certain theoretical basis for Jamesonite with the method of vacuum metallurgical process.The present thesis based on the thermodynamics and volatile process theory discusses the thermal stability and evaporation process of antimony sulfide, lead sulfide and ferrous sulfide under vacuum condition, and performs experiments on principles of the volatilization of these components respectively by using self-built vacuum furnace.The results of thermodynamic calculation show that:under 20 Pa condition, Sb2S3,PbS and FeS decomposition may occur and the corresponding temperature of the beginning of the reaction is 1113 K,1273 Kand 1695 K respectively; Through the evaporation of pure substance mechanism analysis, under the condition of low pressure, evaporation of pure substance is divided into the two processes— the melt surface evaporation and the gas phase diffusion. When the system pressure and temperature is constant, the quantity volatilization of pure material is only related to the area of volatilization.Under the condition of temperature range of 873 K to 1123 K, the system pressure range of 20 Pa-100 Pa, the experimental results indicate that antimony sulfide is detected in the volatile matter. When the system pressure is 20 Pa, the apparent activation energy of volatilization is 57.6 kJ/mol. When the temperature is from 873 K up to 1073 K, the volatile rate increases by 4.37 times, and gas generation mass coefficient decreases, and the boundary layer thickness also increases accordingly, in line with the formula:δ=1.070×10-5 e110.045-0.012.When the temperature is 973 K, the system pressure ranging from 20 Pa up to 100 Pa, the weight loss rate of antimony sulfide reduces 11.4 times, and gas generation mass coefficient decreases, and the boundary layer thickness increases then decreases, in line with the formula δ=0.13804-0.00422p+4.33 ×10-5p2.Under the condition of temperature range of 923 K to 1173 K, the system pressure ranging of 20 Pa-100 Pa, the experimental results signify that the volatilization of lead sulfide is merely lead sulfide. Volatile control step is the gas phase diffusion. When the System pressure is 20 Pa, apparent activation energy of volatilization is 96.7 kJ/mol. When the temperature is from 923 K up to 1173 K, the volatile rate increases by 14.9 times, and gas generation mass coefficient decreases, and the boundary layer thickness also increases accordingly, in line with the formula: δ=5397×10-8 e75.640-0.0063. When the temperature is 973 K, the system pressure from 20 Pa up to 100 Pa, the weight loss rate of antimony sulfide reduces 4.11 times, and gas generation mass coefficient decreases, and the boundary layer thickness increases then decreases, in line with the formula δ=0.01827-2.64024×10-4p+2.05975×10-6p2.Under the condition of temperature with a scope of 973 K to 1173 K, the system pressure of 20 pa, the experimental results of ferrous sulfide show that it almost does not volatilize with little weight loss rate and the residue is FeS. The comparison of the weight loss rate and vaporization pressure of the three kinds of sulfide is that:the weight loss rate of antimony sulfide is higher than that of lead sulfide, which is in turn higher than that of ferrous sulfide, thus separation of them can be available by taking advantage of their different volatilization.