Investigation on high-purity CaCO3 by ammonium sulfate enhanced gypsum dissolution mineralization
In recent years,the technology of using solid waste gypsum to mineralize CO2 and co-produce CaCO3 and ammonium sulfate has received widespread attention.However,due to the complex composition of solid waste gypsum,difficult separation and purification processes,and the difficulty in balancing cost and mineralization products quality,the gypsum mineralization technology is unable to achieve large-scale industrial utilization.Therefore,calcium sulfate and phosphogypsum were used as raw materials and proposed an indi-rect mineralization process,which firstly using ammonium sulfate solution,a liquid phase product of gypsum mineralization,to enhance the dissolution and leaching of calcium sulfate,followed by liquid-solid separation,and then mineralized with the calcium sulfate solution.The effects of ammonium sulfate concentration and dissolution leaching time on the dissolution strengthening process were experimentally investigated,and the effects of ammonium concentration,temperature and mineralization reaction time on the mineralization process and mineralization products were discussed as well.The optimized dissolution and mineralization process conditions were determined,ba-sing on which the indirect mineralization process of phosphogypsum was further studied.The experimental results show that,compared with direct mineralization,indirect mineralization can increase the purity of CaCO3 products from 82.2％to 98.6％,and can decrease the parti-cle size D50 from 22.00 μm to 10.98 μm.The indirect mineralization process can effectively strengthen the dissolution and leaching process of gypsum,avoid the introduction of external media,and prepare high-purity light CaCO3.The present research can provide basic support for the economic application of CO2 technology for solid waste gypsum mineralization.
CO2 mineralizationdissolution strengtheningCaCO3gypsum based industrial solid wasteresourceful utilization
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