常见净化工艺对磷建筑石膏性能的影响

Effect of common purification processes of phosphogypsum on the properties of building gypsum

为优化磷石膏净化工艺的技术参数,提升磷石膏的综合利用水平,通过对比109个磷建筑石膏pH与力学性能的关系,研究了水洗法和碱中和法对磷建筑石膏性能的影响,结果表明:磷建筑石膏的2 h抗折强度在pH大于6后出现降低,而2 h抗压强度、压折比、凝结时间都随pH的升高而增大;碱中和法预处理后,磷建筑石膏2 h抗折强度满足3.0级的要求,但其绝干抗折强度只能符合2.0级的要求,存在掉级可能;Ca(OH)_(2)的引入会阻滞磷建筑石膏的水化进程,晶体间搭接点减少。可见,不能简单以pH作为磷石膏的净化工艺参数,还应考虑磷建筑石膏后期力学性能的发展。

To optimize the technology parameters of phosphogypsum purification process and improve the comprehensive utilization rate of phosphogypsum,the relationship between pH and mechanical properties of 109 samples of calcined gypsum from phosphogypsum was compared,and the effects of water washing method and alkali neutralization method on the performance of calcined gypsum from phosphogypsum were studied.The results showed that the 2 h flexural strength of calcined gypsum from phosphogypsum decreased after pH exceeded 6,while the 2 h compressive strength,flexural ratio,and setting times all increased with the increase of pH;After alkaline neutralization pre-treatment,the 2 h flexural strength of calcined gypsum from phosphogypsum met the requirement of 3.0 level,but its absolute dry flexural strength could only meet the requirement of 2.0 level,which might mean insufficient performance growth in the later stage;The introduction of Ca(OH)_(2) would hinder the hydration process of calcined gypsum and reduce the overlap points between crystals.It is concluded that pH cannot be simply used as a purification process parameter for phosphogypsum,and the development of mechanical properties of calcined gypsum in the later stage should also be considered.