多级选择性氧化-高温还原回收砷锑烟尘中锑资源的应用基础研究

Plenty of dust containing arsenic and antimony is produced from the process of nonferrous metal anode slime smelting recovery of precious metals in the southwest region of China, and antimony content of it is up to 20-50%. It is of great significance to realize the antimony effective recovery. Based on the arsenic and antimony phase structures in the dust containing arsenic and antimony, a new method of multiple stages selectivity oxidation-high temperature reduction to recover antimony is put forward in this subject. Taking the thermodynamic activity calculation and kinetics strengthening mechanism study as the foundation, mechanisms of oxygen dynamics distribution and separation of arsenic and antimony through selective oxidation are researched with the study of arsenic and antimony oxidation variable valence path and the oxygen element transfer mechanism during the oxidizing roasting process. Simulating of low arsenic oxide volatilization process in the reaction atmosphere (oxidizing atmosphere), behavior characteristics and strengthening mechanism of low valence arsenic oxide volatilization are studied. Then mechanisms of arsenic inhibition reduction and antimony promoting reduction are explored in the molten silicate and aluminates ion structures within the the reduction atmosphere, and the antimony metal micro interface migration strengthening mechanism is constructed taking account into the roasting substrate phase structure. It provides theoretical support for the dust containing arsenic and antimony resource utilization technology development through the improvement the basic theory of dust containing arsenic and antimony multiple stage selectivity oxidation-high temperature reduction to recover the antimony resource.

我国西南地区有色金属阳极泥熔炼回收贵金属过程中多产生含砷锑烟尘，其中锑含量达20-50%，实现其有效回收意义重大。基于砷锑烟尘中砷、锑物相赋存结构，提出多级选择性氧化-高温还原回收锑资源新思路。以热力学活度计算分析和动力学强化机制研究为基础，研究氧化焙烧过程中砷、锑氧化变价路径和氧组元传递机理，探明氧动力学分配机制和砷、锑选择性氧化分离机理，模拟低价砷氧化物在反应气氛（氧化性气氛）中的挥发行为过程，探究其反应气氛（氧化性气氛）中挥发行为特征和强化机制；基于多级选择性氧化后焙烧底物物相结构，掌握还原性气氛中熔融硅酸根、铝酸根离子结构中砷的抑制还原和锑的促进还原机理，并建立锑金属微元界面迁移强化机制。完善砷锑烟尘多级选择性氧化-高温还原回收锑资源基础理论，为砷锑烟尘资源化利用技术发展提供理论支撑。

我国有色金属阳极泥熔炼回收贵金属过程中产生大量砷锑烟尘，其中锑含量20-50%，砷含量20-40%，进行锑资源有效回收意义重大。基于砷锑烟尘中砷、锑物相分布特征和砷、锑氧化还原性质及不同价态砷锑氧化物和硫化物挥发性质区别，项目以固相选择性氧化和气相选择性氧化法高效分离砷锑烟尘中砷、锑为研究主线，系统开展了不同氧势环境中砷、锑组分的选择性氧化机理和物相定向转变规律、砷锑固溶体高效打破机制、氧化性气氛中砷氧化物挥发行为特征和焙烧渣中锑的高效回收机制等研究。主要研究结论有：（1）砷锑烟尘中砷锑固溶体（(As,Sb)2O3）大量存在，且在焙烧过程极易合成，其蒸气压介于As2O3和Sb2O3之间，其是直接焙烧法过程中砷、锑分离效率低的主要原因；（2）以MnO2、CuO为固相弱氧化剂对砷锑烟尘进行氧化焙烧，可将烟尘中游离态Sb2O3和(As,Sb)2O3中结合态‘Sb2O3’选择性氧化为难挥发Sb2O4，并As以As2O3形式高效挥发，实现了烟尘中砷、锑的高效分离，CuO为添加剂时，焙烧温度400°C、焙烧时间100 min和CuO添加量为34.54%条件下，砷挥发除率达91.50%，锑损失率仅8.63%；（3）以空气为氧化剂对对砷锑烟尘进行气相氧化焙烧处理，亦可将游离态Sb2O3和(As,Sb)2O3中结合态‘Sb2O3’选择性氧化为难挥发Sb2O4，实现砷、锑有效分离，同时焙烧体系中加入CaO和Fe2O3可促进砷锑固溶体(As,Sb)2O3氧化解离反应的发生，并减弱过程中砷锑固溶体的重新合成，提高烟尘中砷、锑的分离效率。CaO为添加剂时，空气流量200ml/min，焙烧温度550°C、焙烧时间80 min和CaO添加量为5%条件下，烟尘中砷挥发除率达91.53%，锑损失率仅4.3%；（4）还原焙烧法进行焙烧渣中锑的回收，发现碳热还原法制备金属锑时，锑挥发损失率较大，过程中加入SiO2，可一定程度上抑制金属锑的挥发，温度为800℃、焙烧时间为60min和SiO2添加量为25 wt.%时，金属锑损失率从35.38 wt.%可降至21.35 wt.%。此研究为As2O3和Sb2O3火法高效分离新方法的开发提供了重要的科学参考，同时对高砷锑资源中锑的高效提取提供了一种新方法。