碳-硫混合气氛强化氧化锌硫化热化学机理研究

It is well known that significant amounts of valuable metal zinc exist in steel-making dust slime and refractory zinc oxide ore and zinc is mainly in the form of zinc oxide. The grade of zinc is lower for the smelting process, but suitable for the benefication process. However, it is difficult to recover valuable zinc metals for mineral processing technology due to the nature of complex materials and higher content of mud. In this study, the novel method involving sulfidation roasting of the refractory zinc oxide materials followed by flotation was proposed based on the fact that the key of clean recovery of zinc bearing materials by flotation was high-efficiency sulfidation of zinc oxide minerals. Meantime, it was found that lower utilization of vulcanizing agent and pollution problems caused by emission of SO2 during the sulfidation of zinc oxide. In this study, the intensification of sulfidation process was focused on and a novel sulfidation system involving carbon and sulphur mixture atmosphere was constructed. The thermochemical mechanism of strengthening sulfidation of zinc oxide, involving sulfidation thermodynamics, reaction process, micro-mechanism of reaction based on calculational chemistry and reaction dynamics, was investigated in depth. Theories and methods, involving high-efficiency utilization of vulcanizing agent and pollution of SO2 being effectively controlled during the sulfidation roasting of zinc oxide, were formed and kinetic model of high-efficiency sulfidation for zinc oxide was constructed, to provide theoretical support for the high-efficiency sulfidation of refractory zinc oxide materials.

钢厂冶金尘泥和难处理氧化锌矿中含有大量的有价金属锌，其主要以氧化锌形式存在。物料中锌品位对冶炼工艺来讲相对较低，而作为选矿原料却较为适宜，但由于这些物料性质复杂且泥化严重，致使常规选矿工艺回收锌难度较大。基于实现此类氧化锌物料清洁浮选回收的关键是氧化锌矿物的高效硫化，提出“硫化焙烧—人造硫化矿浮选”的学术思想，同时发现氧化锌硫化过程中存在硫化剂利用率低和二氧化硫污染等问题。本研究着眼于氧化锌硫化过程强化，构建出碳-硫混合气氛强化硫化新体系，从宏观硫化反应热力学、反应历程、微观作用机理研究的计算化学以及反应动力学，对氧化锌强化硫化热化学机理进行深入研究，形成氧化锌硫化焙烧过程中硫化剂高效利用和二氧化硫污染有效控制的理论与方法，建立氧化锌高效硫化动力学模型，为复杂难处理氧化锌物料的高效硫化提供理论依据。

钢厂冶金尘泥和难处理氧化锌矿中含有大量的有价金属锌，其主要以氧化锌形式存在。基于实现此类氧化锌物料清洁浮选回收的关键是氧化锌矿物的高效硫化，提出“硫化焙烧—人造硫化矿浮选”的学术思想。本项目采用HSC6.0热力学软件中“Equilibrum Composition”模块，构建了氧化锌强化硫化反应热力学模型，证实碳-硫混合气氛强化氧化锌硫化反应的可行性；采用非等温与等温热重分析、XRD和SEM-EDS分析，发现氧化锌与黄铁矿在500℃附近就会发生硫化反应，产物主要为硫化锌、磁黄铁矿（Fe1-xS）及Fe2.964O4，但形成的硫化锌矿晶体颗粒较小、晶形较差、颗粒间隙较大，进一步提高温度至850℃时，合成较好人造铁闪锌矿晶体粒度增加；采用Metarials Studio 8.0软件中的CASTEP模块，发现S2在ZnO表面的吸附能引起氧化锌晶体表面的几何结构和原子电子特性的显著改变，首先会使Zn-O键发生解离，同时S2中的两个硫原子反生歧化反应，分别与锌原子和氧原子结合生成ZnS和SO2；浮选试验结果表明，氧化锌矿物在硫基气氛下通过表面热化学改性后浮选回收效果显著增加，通过XRD、EPMA和XPS分析，查明了高温表面改性后，在矿物表面发现有锌的硫化物生成，主要由硫化锌和二硫化锌组成，进一步揭示了氧化锌矿物表面热化学改性机理以及表面疏水性演变规律；以锌金属储量排名世界第三和亚洲第一的云南兰坪氧化锌矿为研究对象，基于“硫化焙烧-浮选”的选冶联合新思想，对其进行试验研究，使原矿锌品位由7.84%提高至32.05%，浮选精矿中锌回收率提高至91.29%，浮选效果显著；进一步对钢厂高炉烟灰进行碳-硫混合气氛下的硫化转化试验，使得物料中锌的硫化率由近0%增加到92.01%，为后续浮选回收创造了条件。通过该项目的研究，建立了氧化锌硫化焙烧过程中硫化剂高效利用和二氧化硫污染有效控制的理论与方法，形成了复杂锌资源选冶联合清洁利用研究方向。