硫化法去除工业磷酸中的镉

Removal of cadmium ions from industrial phosphoric acid by vulcanization method

对比研究了无机及有机硫化剂(分别为Na2S和Na3S3C3N3)对工业磷酸中Cd^2+的去除效果,分别研究了硫化剂类别、磷酸质量分数、硫化物用量、Cd^2+初始浓度、转速、共存离子对Cd^2+去除效果的影响。结果表明:使用无机硫化剂时,Cd^2+去除率随Na2S用量增加、转速及磷酸质量分数减小而增加,当Cd^2+初始质量浓度为40~100mg/L时,Cd^2+去除率均可达99%以上;而使用有机硫化剂时,Cd^2+去除率随Na3S3C3N3用量增加呈先增后减的趋势,随转速及磷酸质量分数的减小而增加,当Cd^2+的初始质量浓度为20~80mg/L时,Cd^2+的去除率为97%;两种硫化剂对镉的去除效果均受As^3+和Pb^2+抑制。综上可知,硫化法可高效去除工业磷酸中Cd^2+等有害金属元素,与有机硫化剂相比无机硫化剂适用于更高含镉浓度工业磷酸中镉的去除。

The effects of inorganic and organic vulcanizing agents (Na2S and Na3S3C3N3,respectively) on the removal of Cd^2+ from industrial phosphoric acid are studied.The effects of types of vulcanizing agents,mass fraction of phosphoric acid,amount of sulfide,initial concentration of Cd^2+,rotational speed and coexisting ions on the removal of Cd 2+ are studied.The results show that the removal rate of Cd^2+ increases with the increase of Na2S dosage,the decrease of rotational speed and the mass fraction of phosphoric acid.When the initial mass concentration of Cd^2+ is 40-100 mg/L,the removal rate of Cd^2+ can reach more than 99%.When organic vulcanizing agent is used,the removal rate of Cd increases first and then decreases with the increase of Na3S3C3N3 dosage,and with the increase of rotational speed and phosphoric acid content.When the initial mass concentration of Cd^2+ is 20-80 mg/L,the removal rate of Cd^2+ is 97%.The removal efficiency of cadmium by both sulfides is inhibited by As^3+ and Pb^2+.In conclusion,the sulfidation process can effectively remove harmful metal elements such as Cd^2+ in industrial phosphoric acid,and inorganic sulfides are suitable for the removal of cadmium in industrial phosphoric acid with higher cadmium concentration than organic sulfides.