脱硫石膏制备碳酸钙晶体的生长成核过程研究

Nucleation growth of calcium carbonate crystals prepared by gypsum

以脱硫石膏资源化循环利用为目的,碳酸铵、添加剂(二水合柠檬酸三钠、硫酸、十六烷基溴化铵)为原料,在程序搅拌控制条件下制备碳酸钙晶体,利用XRD和微机差热天平对产物的组成、晶型和热稳定性进行分析。添加二水合柠檬酸三钠和十六烷基溴化铵得到的是单一的方解石型碳酸钙;而添加硫酸得到的是方解石、球霰石和文石3种晶型共存的碳酸钙晶体。最佳的程序搅拌方案是实验开始前40 min以450 r/min的速率快速搅拌,提高扩散速率和化学反应速率;然后以350 r/min速率搅拌40 min,为晶型生长成核做准备;最后40 min以250 r/min速率搅拌,促进完整碳酸钙晶型的形成。

With gypsum, ammonium carbonate and additives （trisodium citrate dihydrate, sulfate, CTMAB） as the raw material, calcium carbonate was prepared under the program stirring to achieve the purpose of gypsum resource recycling. The composition, crystal structure and thermal stability of product were studied. When adding trisodium citrate dihydrate and CTMAB, the product obtained was a single calcite calcium carbonate; while adding sulfuric acid, the calcium carbonate crystals with calcite, aragonite and vaterite were obtained. The best solution of agitation program is as follows ： rapidly stirring in a rate of 450 r/min in 40 rain before the experiment starts so as to improve the rate of diffusion and chemical reaction rate, and then the system is stirred for 40 rain in a rate of 350 r/ rain, which are ready for the preparation of crystalline growth nucleation. The stirring speed is 250 r/min in the last 40 rain to promote the formation of complete crystalline calcium carbonate.