高砷炼铜烟灰短流程资源化过程中砷深度分离与高效富集技术基础

With the pressure on the resource and environment being increased, the deep separation and the highly efficient enrichment of arsenic have become the bottlenecks in the resourcization of copper smelting dusts and the harmless disposal of arsenic. Since arsenic can be enriched easily in alkali system in safety, a new process of “alkali leaching under pressure - synergistic sulfidation - solvent extraction of arsenic” is proposed, by which a highly efficient enrichment of arsenic and a successful recovery of the valuables in the dusts in short process can be achieved in the meantime. The researches on the control of the selectivity and directionality of the sulfidation reactions of lead, zinc and arsenic as well as the control of the extraction capability of modified quaternary ammonium salt extractants are carried out in alkali system in this project. Both hydrometallurgical and mineralogical methods and quantum chemistry calculation are applied in this project research. The principles of the sulfidation reactions of lead, zinc and arsenic as well as the crystallization behavior of lead and zinc are discovered and the structure-efficiency of the modified quaternary ammonium salt extractants are further discussed. Based on the researches stated above, the regulatory mechanism of the anion-exchange capability of the extractants can be built up finally. Furthermore, the process of “alkali leaching under pressure - synergistic sulfidation - solvent extraction of arsenic” can be optimized. This project research can also lay the theoretical foundation of the system integration of the technologies of the resourcization in short process and the harmless disposal of arsenic of other intermediate materials containing arsenic in addition to smelting dusts.

在资源与环境的双重压力下，砷的深度分离与高效富集已成为高砷炼铜烟灰资源化与砷无害化处置的瓶颈。鉴于碱性体系中更易安全地实现砷的集中，申请者创新性地提出了“密闭碱浸－双硫化协同－溶剂萃取脱砷”耦合工艺，巧妙地同时解决了砷高效富集和有价金属短流程回收的问题。本课题基于该创新工艺，采用湿法冶金、工艺矿物学和量子化学计算相结合的方法，研究碱性体系中铅、锌、砷硫化反应的选择性、定向性调控以及改性季铵盐萃取剂对砷的萃取能力可控性等关键科学问题。籍微观层次的界面化学和多元多相体系的冶金物理化学的系统研究，揭示铅、锌与砷的硫化反应及结晶行为规律，探明改性季铵盐萃取剂构效关系，建立萃取剂阴离子交换能力的调控机制。基于本课题研究，“密闭碱浸－双硫化协同－溶剂萃取脱砷”耦合的创新工艺将得到进一步完善。而且，本课题研究也将为铜冶炼行业产出的其他含砷物料短流程资源化及砷无害化处置技术的系统集成奠定理论基础。

针对铜冶炼烟灰中As难以集中治理的问题，研究并提出“碱浸硫化脱砷预处理-改性季铵盐萃取”新工艺，为铜冶炼烟灰资源化及As无害化处置提供了新的可选方案。本文的主要研究内容如下：.研究比较铜冶炼烟灰中As在浸出温度303～363 K范围内，在NaOH和NaOH+Na2S体系中的浸出速率差异。经动力学研究证实，在NaOH+Na2S浸出体系中，在303～363 K温度范围内，烟灰中As浸出过程受内扩散控制，浸出动力学方程遵循未反应收缩核模型。研究并制定了NaOH+Na2S体系铜冶炼烟灰常温浸出脱As的较优工艺，As浸出脱除率保持在94%左右，渣含As降至0.5%～0.6%左右，As与Cu、Pb、Zn等有价金属得以有效分离，工艺具有良好稳定性。.通过对本季铵盐萃取体系负载有机相中砷的反萃剂的一系列筛选，择取了能够同时满足高效反萃和直接生成可循环利用的再生有机相两个要求的低浓度H2O2和饱和Na2CO3的复合溶液作为反萃剂。实验研究表明反萃过程中引入H2O2是实现负载有机相高效反萃的重要原因，微量H2O2可以使该体系中的AsⅢ快速氧化成AsⅤ，且反萃时 H2O2的添加顺序不影响实验结果。AsⅢ与AsⅤ的萃取对照实验揭示了负载有机相中砷的反萃机理：AsⅢ和AsⅤ与季铵盐阳离子缔合能力存在差异，相对来说，AsⅢ与季铵盐阳离子缔合能力强而AsⅤ与季铵盐阳离子缔合能力弱，这使萃取过程水相料液中的AsⅢ易与萃取剂有机相中的CO32-进行交换而获得高效萃取率，而反萃过程引入低浓度H2O2将负载有机相中的AsⅢ氧化成AsⅤ后被反萃剂溶液中的CO32-快速交换下来，进而呈现出高反萃率。因此体系中引入微量H2O2之后应该主要参与了AsⅢ的氧化还原反应，而对体系中硫元素则未见明显影响。砷的反萃与循环萃取工艺研究结果显示：4%H2O2 +饱和Na2CO3溶液为反萃剂时，在常温25℃，相比1:1，油水接触时间7min的条件下，砷的反萃率达到99%以上，反萃同时生成了可直接利用的CO32-型N263有机相，且循环萃取实验和对有机相的红外光谱分析结果都表明该再生有机相的循环性能良好。