SrCO₃ producing optimization from celestine mineral and kinetic reaction modeling

Iran is rich in mineral resources such as Celestine. On the basis of estimations, the capacity of mineral Celestine is over two million tons with 75-95% strontium sulfate purity. Strontium sulfate directly is not a major feed in industries, but it has a huge consumption in the form of strontium carbonate in many industries such as Color cathode Ray Tubes, pyrochemical process, ceramics, paint production, zinc purification process. Two conventional methods are used to produce strontium carbonate from strontium sulfate including direct reaction method and black ash method. In this work, the second method was analyzed and optimum condition of many operational condition and process parameters were determined. In the black ash method, firstly, mineral Celestine was reduced with coke at high temperature and strontium sulfate was reduced to strontium sulfide. In according to high solubility of sulfide in hot water, strontium sulfide was separated by leaching process. Then, strontium sulfide was reacted with sodium carbonate and strontium carbonate was produced. One isolated system was designed and prepared properly to analyze operational condition and process parameters including process temperature, residence time, feed particle size distribution and the effect of excess coke on conversion. The results showed that the reduction reaction occurred for temperature more than 800 ^deg^C. Also, smaller particle size led to better reaction conversion which is related to more surface provided. It was found that using more than 20% excess coke in the process, increases the efficiency by 4%. However, using more than 25% excess coke has not any positive effect on reaction process and conversion. Mass transfer resistance analysis showed that the most important resistance to reaction is diffusion throughout black ash layer which is controlling phase to reduction reaction. Thus, black ash layer is the most important parameter to control the rate of reaction. Finally, optimum condition is determined at temperature 1100 ^deg^C, residence time 2 hours in reduction furnace, particle size distribution including coke and Celestine substance in 100 to 500 mesh, excess coke 25% with 75% reaction efficiency and high reliability and economical explanation