磷化渣废液除锌制备高纯度磷酸三钠  

Preparation of high-purity trisodium phosphate from the phosphating slag waste liquid after the removal of zinc

作　　者：曾璐婵 李雲 郭宏飞[1,2] 张金凤 曹吉林 Luchan ZENG;Yun LI;Hongfei GUO;Jinfeng ZHANG;Jilin CAO(College of Chemical Engineering and Technology,Hebei University of Technology,Tianjin 300130,China;Hebei Provincial Key Laboratory of Green Chemical Technology and High Efficient Energy Saving,Tianjin 300130,China;Tianjin Academy of Eco-Environmental Sciences,Tianjin 300384,China)

机构地区：[1]河北工业大学化工学院,天津300130 [2]河北省绿色化工与高效节能重点实验室,天津300130 [3]天津市生态环境科学研究院,天津300384

出　　处：《过程工程学报》2022年第4期478-486,共9页The Chinese Journal of Process Engineering

基　　金：河北省自然科学青年基金资助项目(编号:B2020202081);2020年河北省研究生创新资助项目(编号:CXZZSS2020037)。

摘　　要：为了实现磷化渣碱溶后所得废液的综合利用,采用中和沉淀法和硫化钠沉淀法去除磷化渣废液中的杂质锌,对中和沉淀法和硫化钠沉淀法的工艺条件进行优化,并由此设计磷化渣废液除锌制备高纯度磷酸三钠的生产工艺。对于中和沉淀法,在反应体系pH=8.85,反应时间为10 min时,Zn^(2+)去除率可达97.96%;对于硫化钠沉淀法,在反应体系pH=6.85,硫化钠投加量与Zn^(2+)的摩尔比为1:1,反应时间为10 min时,Zn^(2+)去除率可达99.80%。相比于中和沉淀法除锌制备磷酸三钠工艺,硫化钠沉淀法除锌制备磷酸三钠工艺具有更高的磷酸三钠纯度,为98.85%,固相产品中Zn^(2+)含量更低,仅为0.0004%,符合化工行业分析纯标准。该工艺大幅度地回收了磷化渣废液中的PO_(4)^(3-)离子和Na^(+)离子,为实现磷化渣综合利用的工业化提供新思路。Phosphating slag is the hazardous waste produced during the phosphating process,which has an adverse effect on the quality of phosphating coating and phosphating cost.It is an effective method to utilize phosphating slag by extracting iron and zinc ions from phosphating slag via alkali dissolution;however,the treatment of liquid waste of residual phosphating slag is a challenge topic.In this work,the neutralization and sodium sulfide precipitation methods were used to remove the zinc from the phosphating slag waste liquid.The corresponding process conditions were optimized.And the production processes of highly purified trisodium phosphate from phosphating slag waste liquid after zinc removal were designed respectively.The removal rate of Zn^(2+) could reach 97.96%via neutralization precipitation method under the pH of the reaction system of 8.85,and the reaction time of 10 min,while the removal rate of Zn^(2+) could reach 99.80%via the sodium sulfide precipitation method under the pH of the reaction system of 6.85,the molar ratio of sodium sulfide to Zn^(2+) of 1:1,and the reaction time of 10 min.After adjusting the pH of the treated waste liquid to 12.30±0.03 by using 10 mol/L of NaOH solution,the phosphate anions and sodium ions were recovered by cooling and crystallization at 5℃to produce the trisodium phosphate.The trisodium phosphate produced from waste liquid after zinc removal by neutralization precipitation method possessed the purity of 97.72%and Zn^(2+) content of 0.0014%,which is in line with the chemical industry standard of chemical purity.Compared with the production process of trisodium phosphate after zinc removal by using neutralization precipitation method,that using sodium sulfide precipitation method exhibited higher purity of trisodium phosphate with the value of 98.85%,and lower Zn^(2+) content in trisodium phosphate with the value of 0.0004%,which met the analytical purity standard of the chemical industry.The process is capable of efficiently recovering the PO_(4)^(3-)and Na^(+) ions f

关 键 词：磷化渣废液 资源化利用 除锌 中和沉淀法 硫化钠沉淀法 磷酸三钠 

分 类 号：TQ131.12[化学工程—无机化工] X703[环境科学与工程—环境工程]