Migration Law Of Sulfer In Pre-treatment Of Stainless Steel Acid-pickled Sludge

In view of large yield,serious pollution and difficult disposal of acid-pickled sludge,the technical idea of returning acid-pickled sludge to smelting process so as to recycle valuable metals Fe,Cr and Ni and exert auxiliary functions of CaO and CaF2 et al was proposed in this paper,expecting to realize the goals of sludge detoxification,digestion and resource utilization.It's found through calculation with Fact Sage thermodynamics software that most valuable metals Fe,Cr and Ni in acid-pickled sludge could be recycled and enter molten metal,but in the meantime,high sulfur content in the sludge would result in resulfurization in molten metal.Based on this,a theoretical study of thermodynamics of sludge pre-treatment desulfurization was conducted,and results indicated that: complete desulfurization temperature of pure acid-pickled sludge under inert environment was above 1,400?;after 0.5%-0.8% carbon was added,its complete desulfurization temperature was below 1,000?.Finally,sulfur decomposition of calcium sulfate into SO2.The influence of pret-reatment desulphurization was researched by experiment: The decomposition temperature of calcium sulfate started with 1000? ended with 1400? in inert environments,S emitted in the form of SO2,lower heating rate(10?/min)and longer time(10 ? /min)were better for the reaction,maximum desulphurization rate was 85.6%.Carbon was used as the reducing agent in reducing atmosphere.Calcium sulfate decomposition temperature started with 800 ? in reducing atmosphere,S emitted in the form of SO2.The optimum carbon ratio of 0.8% could conduct the final reaction temperature below 1000?.lower heating rate(10?/min)and longer time(10 ? /min)were better for the reaction.Maximum desulphurization rate was 91.26%.The non-isothermal thermal decomposition kinetics of the process of desulfation in argon atmosphere was studied by TG-DTG techniques.Desulfurization process show that heating rate is restrictive link,low heating rate is well for removal of sulfur in the sludge.The non-isothermal kinetics parameters were analyzed by means of model-free(Flynn-Wall-Ozawa and Vyazovkin)and model fiting(Satava-Sastak)methods,respectively.The apparent activation energy of the thermal decomposition reaction was obtained to give: E=492.9097 kJ·mol-1,and the kinetic equation may be expressed as:(?).The research achievement has enriched theory and practice of acid-pickled sludge pre-treatment desulfurization and promoted resource utilization of acid-pickled sludge in metallurgical enterprises.