铜渣熔融还原提铁协同尾渣再生制备高性能陶瓷的基础研究

Based on the status, problems and trends of the comprehensive utilization technology of copper slag, a new idea of recovery of the valuable metals from molten copper slag using aluminum ash as reductant along with the reuse of slag tailings as high performance ceramics is proposed in this project. With the help of the thermodynamic analysis and experimental study, the evolution of the structure and thermo-physical properties of slag during reduction will be revealed. On this basis, the migration laws of the valuable components as well as the dynamic behaviors are further explored, and the key factors with regard to this process will be determined. After magnetic separation, the tailings will be reused for the preparation of anorthite based ceramics considering its characteristics, and the microstructure, sintering behavior, control mechanism of properties of this recycled ceramic will be clarified. In addition, the internal connection between reduction technique and ceramic properties will also be established. The above research works will provide significant theoretical guidance for the recovery of the valuable elements from copper slag with low-cost, high efficiency and cleanliness, as well as the recycling of other components with high added-value. As a new type of utilization technology of copper slag with all-components, this method has the features of “green, short process and waste control by waste”. Besides, there are also many new scientific issues regarding this study, thus possessing both theory and application values.

本申报项目结合铜渣综合利用技术研究现状、存在问题及发展趋势，提出了利用铝灰处理熔融铜渣提取有价金属及制备高性能尾渣再生陶瓷的新构想。拟通过热力学分析和实验研究，揭示还原过程中熔渣结构和热物理性质的演变规律及其内在联系。在此基础上，进一步探索有价组元的迁移规律及其调控机制，并建立熔融还原过程的宏观动力学模型、确定影响还原效果的关键环节；结合尾渣特点，继续开展利用提铁尾渣制备钙长石基陶瓷的研究工作，重点阐明尾渣再生陶瓷的微观结构特征、烧结行为、影响性能的核心因素及其调控机制，构建还原工艺参数与陶瓷性能的内在关系。上述研究工作可为铜渣有价资源的低成本、高效、清洁回收及低阶组分的高附加值循环利用提供重要理论指导。作为一种新型的铜渣“全组分资源化”处理技术，该工艺具有“绿色、短流程、以废治废”等特色，而且还涉及诸多新的科学问题，因此本研究具有理论与应用的双重价值。

针对目前铜渣综合利用技术存在的有价资源回收成本高、能耗大、效率低、流程长及尾渣利用率低等问题，本项目开展了利用铝灰处理熔融铜渣深度回收有价金属及制备尾渣再生陶瓷材料的研究工作，在对熔融还原过程进行平衡计算的基础上，结合热力学计算和实验研究，系统研究了还原温度、改质碱度、铝灰/铜渣比、助熔剂添加及铝灰/煤粉配比等因素对铜渣中有价金属回收率的影响规律及其作用机理，并阐明了影响金属还原-分离行为的关键环节及其调控机制。项目取得的主要研究进展及重要结果如下：(1) 改质碱度[w(CaO/SiO2)]对于铜渣铝灰熔融还原-金属分离过程具有重大影响，较高的改质碱度不仅能有效抑制熔渣与坩埚间的反应，避免固相析出物的形成，同时还能有效降低熔渣结构聚合度和黏度，进而促进还原金属的沉降分离。当还原温度为1600oC、改质碱度为0.9时，Fe和Cu的直接回收率分别为98.6%和98.3%；(2) Na2CO3添加可有效降低铝灰处理熔融铜渣所需的还原温度。其添加不仅能有效破坏Al2O3含量过高而导致的复杂网络结构，同时还能进一步抑制MgO坩埚向熔渣中的溶解，导致熔渣流动性显著提高。当Na2CO3添加量为6 wt%时，铜渣经1550oC(R=0.9)熔融还原后便可实现有价金属的深度回收(Fe、Cu回收率≥98.6%)；(3) 阐明了铝灰-煤粉对改质熔融铜渣的共还原机制，确定了最佳的还原剂比例。在1550oC条件下，使用50%铝灰+50%煤粉的混合还原剂，既能避免碳热还原带来的泡沫渣效应，又能避免还原末期渣中Al2O3含量过高而导致的熔渣变黏问题，从而也实现了有价金属的深度回收(Fe、Cu回收率≥98.0%)；(4) 以提铁尾渣和高岭土为主要原料制备了钙长石基陶瓷，通过材料成分和烧结制度优化设计最终获得了体积密度≥2.10 g/cm3，气孔率≤30%，抗压强度≥50 MPa，重金属类污染物浸出率符合国家环保标准的陶瓷材料。项目共发表学术论文12篇，其中SCI检索论文9篇，获得国家发明专利授权2项，培养博士和硕士研究生各2名。