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氧氯化锆是重要的锆盐基础化工产品。我国是全球最大的氧氯化锆产品生产国和出口国，年产量占世界总产能的90%以上。氧氯化锆的主要生产工艺为氢氧化钠碱熔法，生产每吨氧氯化锆排放约0.2-0.4 m3的锆冶炼废酸。该废酸的酸度高达4～6 mol/L，且含有30多种有价元素，如钪、锆及稀土等，具有十分重要的资源回收价值；同时，废酸中含微量的伴生放射性元素，存在潜在的环境危害。当前的锆生产企业一般采用中和方式处理废酸，其中的有价元素资源利用率低，且产生大量污泥。目前，针对锆冶炼废酸综合回收利用开展的研究不多，主要集中在萃取回收废酸中的钪等有价元素。因此，开展锆冶炼废酸资源化利用的应用基础研究，实现废酸及有价元素的综合利用，具有重要的工业实践意义。本课题旨在开发一种锆冶炼废酸资源化利用新方法。该工艺基于扩散渗析膜分离、溶剂萃取、化学沉淀等技术，为锆冶炼废酸的综合处置提供一条新途径。课题主要工作如下：（1）系统研究了扩散渗析法回收盐酸的过程规律与机理。主要探究了进料酸浓度、进料流量、水酸比等工艺参数对扩散渗析过程的影响，并通过无因次方法，针对特定的DF-120膜建立盐酸浓度和膜内渗透系数P的经验公式，简化传质模拟，提出了预测盐酸回收率的经验模型，对实验数据与模型模拟进行比较，验证模型准确性。结果表明，扩散渗析法可回收锆冶炼废酸中的80%以上盐酸，并截留主要杂质离子。（2）以溶剂萃取法对扩散渗析所得残液进行钪的提取，实现了钪的富集回收。最佳的萃取条件为：以4%P204+3%TBP+3%异十三醇+90%煤油为萃取相，相比（O/A）为1/2，萃取时间为5 min；以3 mol/L HCl溶液为负载有机相洗涤液，有效去除Fe杂质，以3 mol/L NaOH溶液为反萃液，反萃温度为55℃，钪的反萃率和总回收率分别可以达到89.66和88.34%。（3）开展萃取钪后的萃余液中锆、钛的富集回收，以磷酸作沉淀剂，研究了沉淀剂加入量对萃余液中锆、钛及其他元素沉淀率的影响。研究表明，可实现萃钪的萃余液中锆、钛等有价元素的富集。;ZrClO2 is an important chemical product based on zirconium salt. China is the world's largest producer and exporter of zirconium oxychloride products, whose annual output accounts for more than 90% of the world's total output. The main production process of zirconium oxychloride is sodium hydroxide alkaline melting method, which produces zirconium oxychloride emission of about 0.2-0.4 m3 of zirconium smelting waste acid per ton. The acidity of the waste acid is up to 4 ~ 6 mol/L, and contains more than 30 valuable elements, such as scandium, zirconium and rare earth. At the same time, the waste acid contains trace of associated radioactive elements, which is potentially harmful to the environment. Currently, zirconium producers generally use neutralization method to treat waste acid, in which the utilization rate of valuable element resources is low and a large amount of sludge is generated. At present, there are few researches on the comprehensive recovery and utilization of waste acid from zirconium smelting, mainly focusing on the extraction and recovery of valuable elements such as scandium from waste acid. Therefore, it is of important industrial significance to carry out the applied basic research on the resource utilization of waste acid in zirconium smelting and realize the comprehensive utilization of waste acid and valuable elements.The purpose of this project is to develop a new process of recycling waste acid from zirconium smelting. Based on the techniques of diffusion dialysis membrane separation, solvent extraction and chemical precipitation, the process provides a new way for the comprehensive disposal of waste acid in zirconium smelting. The main work of the project is as follows:（1）The law of recovery of hydrochloric acid by diffusion dialysis was systematically studied, and the influence of technological parameters such as the concentration of acid, the flow rate of acid and the ratio of water to acid on the process of diffusion dialysis was investigated. By dimensionless method, the empirical formula of hydrochloric acid concentration and membrane permeability coefficient P was established for a specific DF-120 membrane, the mass transfer simulation was simplified, and the empirical model for predicting hydrochloric acid recovery was put forward. The results showed that the diffusion dialysis method could recover more than 80% of the hydrochloric acid and retain the main impurity ions.（2）Scandium was extracted by solvent extraction and scandium was recovered. With 4% P204+3% TBP+3% modification agent +90% kerosene as extraction system, the extraction time selected for 10 min, (O/A) elected 1/2. 3 mol/LHCl solution, as the loaded organic phase detergents, could effectively remove Fe impurities. With 3 mol/L NaOH solution as the stripping solution and stripping temperature of 55℃, the stripping rate and total recovery of scandium could reach 89.66% and 88.34%, respectively.（3）Enrichment and recovery of zirconium and titanium in raffinate after extraction of scandium was carried out. Phosphoric acid was used as precipitant. The effect of the amount of precipitant added on the precipitation rate of zirconium, titanium and other elements in raffinate was studied. Studies showed that zirconium, titanium and other valuable elements can be enriched in the raffinate of scandium.
|孙帅. 锆冶炼废酸资源化利用应用基础研究[D]. 中国科学院大学,2020.|
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