碳酸钙处理工业废硫酸的硫酸钙结晶与过滤性能研究  

Study on crystallization and filtration properties of calcium sulfate for treating industrial waste sulfuric acid with calcium carbonate

作　　者：罗亚 周容 吕莉[1] 杨杰[1] 唐盛伟[1] 张涛[1] LUO Ya;ZHOU Rong;LÜLi;YANG Jie;TANG Shengwei;ZHANG Tao(School of Chemical Engineering,Sichuan University,Chengdu 610065,China;Sichuan Sanlian New Materials Co.,Ltd.,Chengdu 610101,China)

机构地区：[1]四川大学化学工程学院,四川成都610065 [2]四川三联新材料有限公司,四川成都610101

出　　处：《无机盐工业》2024年第12期127-133,共7页Inorganic Chemicals Industry

基　　金：四川省科技计划资助项目(2022ZHCG0136)。

摘　　要：中国工业低浓度废硫酸产量巨大,由于回收难度大、成本高,通常采用钙盐中和并转化为工业石膏。然而,工业石膏含水率高,导致石膏中可溶性杂质含量高、处理和利用成本高。硫酸钙晶粒细小、过滤性能差是石膏含水率高的主要原因。探讨了不同钙盐沉淀剂的硫酸钙成核机理及晶体形貌,研究了不同工艺条件下CaCO_(3)沉淀剂对硫酸钙晶体成核速率、晶粒尺寸和含水率的影响。结果表明,以CaCO_(3)为沉淀剂,硫酸钙晶体在CaCO_(3)固体颗粒表面原位生长,成核速率受H^(+)浓度和CaCO_(3)加入量影响。在反应温度为30℃、搅拌速率为300 r/min、硫酸质量分数为5%、CaCO_(3)加入速率为0.45 g/min、pH=2、反应时间为30 min的条件下,得到平均粒径约为20μm的针状二水硫酸钙,含水率为36.3%。加入质量分数为0.04%的十二烷基硫酸钠(SDS),二水硫酸钙平均粒径达到50μm,同时宽化生长成片状结构,含水率降低至26.4%。低温、慢速加入CaCO_(3)沉淀剂,避免硫酸钙晶体爆发式成核是降低石膏含水率的关键,加入SDS助剂可调控石膏形貌、促进晶体生长,进一步提高石膏的过滤性能。The output of industrial waste sulfuric acid with low concentration is huge in China.Due to the difficulty and high cost of recovery,it is usually neutralized by calcium salt and converted into industrial gypsum.However,the high content of soluble impurities in gypsum and the high cost of treatment and utilization are caused by the high moisture content of industrial gypsum.The main reason for the high moisture content of gypsum is the fine grain of calcium sulfate and poor filtration quality.In this paper,the nucleation mechanism and crystal morphology of calcium sulfate with different calcium salt precipitants were investigated,and the effect of the nucleation rate,grain size and moisture content of calcium sulfate crystals by the precipitant of CaCO3 at the different reaction conditions were studied.The results showed that the crystal nucleus of calcium sulfate formed in situ on the surface of calcium carbonate particles,and the nucleation rate was affected by the concentration of H+and the amount of CaCO3 added.At the conditions of sulfuric acid of 5%,reaction temperature of 30℃,stirring rate of 300 r/min,adding rate of CaCO3 of 0.45 g/min,pH=2 and reaction time of 30 min,the calcium sulfate crystals were acicular structure with an average particle size of 20μm,which moisture content was 36.3%.Adding w(SDS)=0.04%,the calcium sulfate crystals showed a flake structure,the average particle size was increased to 50μm and the moisture content was decreased to 26.4%.The key to reduce the moisture content of gypsum was to avoid the rapid formation of calcium sulfate crystal nuclei in large quantities.The nucleation rate of calcium sulfate could be reduced by adding calcium carbonate slowly at low temperature.SDS could regulate the morphology of gypsum,promote the crystal growth,and improve the filtration performance of gypsum.

关 键 词：工业石膏 结晶 过滤性能 含水率 

分 类 号：TQ132.32[化学工程—无机化工]