粉煤灰矿物学解析及其稀贵金属赋存机理研究

Coal fly ash is viewed as a major potential source of rare and precious metals, but now, it was wasted. As we had known, the rare metals contents are too lower for their usage, and the alkaline of the ash is high. Due to these properties, the metal recovery form the ash with the leaching process was far from application. At first, the process mineralogy analysis for the ash would be proceed, the mineral composition and the rare metals occurrence characteristics would be tested. Based on that, method for the rare metals beneficiation could be scaled. Secondly, mechanism for the form transformation and the migration during the incineration process would be studied, furthermore, the crystal structure of the typical mineral would be investigated. Based on that, the mechanism for the metals leaching could be resolved. With this subject, the beneficiation and the leaching procedure for the rare metals recovery could be proposed, and the comprehensive usage of the coal fly ash would be realized.

粉煤灰中含有多种稀贵金属元素，直接随粉煤灰排放将造成巨大的资源浪费。由于目前国内外缺乏粉煤灰工艺矿物学及稀贵金属的赋存机理的相关研究，金属的回收仍以直接酸浸提取法为主，资源利用率低。本项目拟从矿物学角度，结合电子探针、红外扫描电镜-能谱仪、化学溶解物相分析法等技术手段，系统解析粉煤灰各组分的矿物组成与稀贵金属的赋存特征，为稀贵金属的特征矿物分选富集提供理论依据；并通过煤炭燃烧过程中稀贵金属形态转化及迁移分布热力学及动力学机理研究，结合单矿物结晶结构解析，阐明稀贵金属结晶结构特征，为稀贵金属的浸出回收奠定理论基础。通过粉煤灰矿物学研究及稀贵金属赋存特征解析，指导稀贵金属-浸出工艺开发，从而最终实现粉煤灰稀贵金属资源的综合回收。

项目选取了内蒙、贵州、湖南、广东、广西等地区的代表性燃煤电厂、燃煤工厂的粉煤灰样品共132个。分别分析了样品中Au、Pd、Pt等铂族元素，Ag、Ga、Ge等稀贵金属元素以及Cu、Pb等常规金属元素的含量。分析结果表明，粉煤灰中Au、Pd、Pt、Ag、Ga、Ge等元素的平均含量可达到0.67g/t、1.47 g/t、4.23 g/t、20.1 g/t、2.62 g/t和0.93 g/t，具有较高的综合回收价值。.研究选择一种粉煤灰样品，开展了工艺矿物学及的研究，经矿物学分析表明，未燃尽碳多为多孔性物质，玻璃微珠主要为硅酸盐的不定形相硅酸盐，未燃尽碳及玻璃微珠均不含金属矿物。此外，矿物质包括金属矿物及非金属矿物，金属矿物多以氧化铁为主，非金属矿物包括了碱性物质及硅酸盐物质；矿物质电子探针分析表明粉煤灰的矿物质中的Pt含量与Ni、Cu等金属含量相关性显著。.分选富集可针对性的富集粉煤灰中的稀贵金属，降低粉煤灰浸出回收成本。本文根据粉煤灰各组分的理化性质差异，采用单组分分选得到未燃尽碳、玻璃微珠、矿物质等特征物质，并通过电镜能谱分析了各组分的矿物组成，在得出粉煤灰金属富集特征后，采用重选、浮选等工艺得到富集有Cu、Ni、Pt、Pd等目标金属元素的重质矿物，Cu、Ni、Pt、Pd的富集系数分别为1.45、1.33、1.90和1.60，回收率分别达到了77%、81%、97%及88%。由于分选得到的重质矿物产率为62.24%，说明采用物理分选法可明显降低粉煤灰金属资源浸出回收的成本。.