高砷高硫金矿焙砂碱介质物相重构及原位非氰浸金

High sulfur and high arsenic refractory gold ore accounts for more than 20% of China's gold resources and the proportion is also increasing year by year. Two stage roasting-cyanide leaching process is the main process of gold extraction from high sulfur and high arsenic refractory gold ore. But as the micro coating of iron and silicon phase on the gold, the leaching rate of gold is low and the resources waste is serious. At the same time, as the toxic cyanide was used in the gold extraction process, a great amount of cyanide tailings which are belonging to dangerous solid waste are produced and difficult to be treated. In this project, a new process is proposed in which alkali medium was used to regulate phase structure, dissociative gold inclusion, in-situ synthesizes the non cyanide gold leaching agent and leaches the gold simultaneously. By investigating the key scientific problems of coating mechanism of gold in gold calcine, phase transformation mechanism and strengthen regulation mechanism of inclusion in alkali medium system, in-situ synthesis mechanism of non cyanide gold leaching agent, in-situ non cyanide leaching mechanism of gold, regenerative cycle characteristics of alkali medium and recovery method of gold, the process of phase reconstruction and in-situ non cyanide gold leaching of high sulfur and high arsenic gold calcine using alkali medium was established. In this new process, sufficient dissociation of gold and inclusion was realized, in-situ non cyanide efficient leaching was achieved and the toxic cyanide tailings were eliminated from the source. It is hopeful to provide theoretical and technical support for the promotion of large-scale use of high sulfur and high arsenic refractory gold ore and the relief of the growing shortage of manageable ore.

高砷高硫难处理金矿占我国金矿资源的20%以上，且比例还在逐年增长。两段焙烧-氰化浸金工艺是从高砷高硫难处理金矿中提金的主要方法。但由于金矿焙砂中存在铁、硅物相对金的显微包裹，导致金浸出率低下，资源浪费严重。同时氰化浸金过程采用剧毒氰化物，产生大量毒性氰化尾渣，属于危险固废，处理困难。本项目提出采用碱介质调控金矿焙砂物相结构，解离金包裹体，并同步实现非氰浸金剂原位合成及浸金新方法，通过研究焙砂中金包裹机理、碱介质水热体系中包裹体物相转化机理与强化调控机制、非氰浸金剂原位合成-浸金机理与调控机制、碱介质的再生循环特性及金的回收方法等关键科学问题，建立金矿焙砂碱介质物相重构-原位非氰浸金新方法、新过程，实现焙砂中金与包裹体的充分解离及金的原位高效非氰提取，并从源头消除毒性氰化尾渣的产生，为促进我国高砷高硫难处理金矿的大规模开发利用，缓解易处理金矿日益短缺的压力提供理论与技术支撑。

高砷高硫难处理金矿占我国金矿资源的20%以上，且比例还在逐年增长。两段焙烧-氰化浸金工艺是从高砷高硫难处理金矿中提金的主要方法。但由于金矿焙砂中存在铁、硅物相对金的显微包裹，导致金浸出率低下，资源浪费严重。同时氰化浸金过程采用剧毒氰化物，产生大量毒性氰化尾渣，属于危险固废，处理困难。本项目提出采用碱介质调控金矿焙砂物相结构，解离金包裹体，并实现非氰浸金新方法。研究了焙砂中铁、硅、金等主要物相的赋存形态和分布规律，通过XRD、SEM-EDS、MLA等查明了赤铁矿和石英对金的包裹机理；系统研究了焙砂中石英在碱介质溶液体系中的溶解规律及溶解动力学，获得了最佳脱硅条件，脱硅率可达57.6%，脱硅液制得了水玻璃产品；研究了金矿焙砂中含铁物相在碱介质溶液体系中的转化规律与机理，查明了含铁物相在碱溶液体系中存在赤铁矿-铁酸钠-无定形氧化铁的转化过程，获得了最佳转化条件，转化产物为疏松多孔状态，包裹体被彻底打开，金的浸出率可由80%左右提高至97%左右，尾渣中金品位降低至0.1g/t以下；开发了碱介质焙烧体系转化含铁物相新方法，查明了含铁物相在碱焙烧体系中存在赤铁矿-铁硅酸钠-无定形氧化铁的转化过程，获得了最佳转化条件，转化效果与碱介质溶液体系相当；建立了金矿焙砂碱介质转化-硫代硫酸盐非氰浸金新过程，系统考察了各因素对浸金过程的影响规律，获得了与氰化浸金工艺相当的浸金效果；合成了新型碱介质脱硅剂，可将35%浓度碱介质中的SiO2由10g/L降低至1.5g/L，从而消除硅的积累对碱介质循环过程的影响；测定了80°C下Na2SO4-NaOH-H2O的水盐体系相图，分析了硫酸钠在工艺流程中的走向，并进行了硫酸钠、碳酸钠的结晶脱除研究，查明了碱介质再生循环特性，建立了循环利用方法；完成了吨级/批次中试实验，详细考察了核心反应、分离设备在放大过程中对工艺的影响，系统测定了各工序物性参数以及物料消耗数据，为提金新技术的产业化放大提供了支撑。金矿焙砂碱介质物相重构-非氰浸金新方法实现了焙砂中金与包裹体的充分解离及金的高效非氰提取，并从源头消除了毒性氰化尾渣的产生，为促进我国高砷高硫难处理金矿的大规模开发利用，缓解易处理金矿日益短缺的压力提供了理论与技术支撑。