硫酸铵强化石膏溶解矿化制备高纯CaCO_(3)

Investigation on high-purity CaCO_(3) by ammonium sulfate enhancedgypsum dissolution mineralization

近年来,利用固废石膏矿化CO_(2)联产CaCO_(3)及硫酸铵工艺技术受到广泛关注,然而由于固废石膏成分复杂,分离纯化困难,成本与矿化产品品质难以兼顾导致其无法大规模工业化利用。为此,以硫酸钙及磷石膏为原料,提出以石膏矿化液相产物硫酸铵溶液强化硫酸钙溶解浸出,液固分离后再进行矿化的间接矿化工艺。试验研究了溶解强化过程中硫酸铵浓度及溶解浸出时间对硫酸钙溶解特性的影响,以及矿化过程中氨水浓度、温度、矿化反应时间等因素对矿化过程和矿化产物的影响。确定了优化的溶解与矿化工艺条件,基于此,进一步研究磷石膏的间接矿化过程,结果表明,与直接矿化相比,间接矿化可使CaCO_(3)产品纯度由82.2%提高至98.6%,且产品粒度D_(50)由22.00μm降至10.98μm。间接矿化工艺可有效强化石膏溶解浸出过程,避免引入外加介质,并制备高纯度轻质CaCO_(3),相关研究可为固废石膏矿化CO_(2)技术的经济应用提供基础支持。

In recent years,the technology of using solid waste gypsum to mineralize CO_(2)and co-produce CaCO_(3)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 indirect 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,basing 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 CaCO_(3)products from 82.2%to 98.6%,and can decrease the particle size D_(50)from 22.00μm to 10.98μm.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 CaCO_(3).The present research can provide basic support for the economic application of CO_(2)technology for solid waste gypsum mineralization.