复杂金矿焙烧氰化过程中银迁移行为及物相重构规律

The silver leaching rate is only about 50% in complex gold ore roasting-cyaniding process, caused by the phase of silver migrating and forming occlusion by silicates and iron salts. Traditional research mainly focused on roasting process improvement, roasting additive selection and optimization of cyanide process and with less research on formation mechanism of silver occlusion. In this topic through study the thermodynamic of roasting process, system research the law of Ag occurrence state transfer, migration in oxidizing roasting - acid leaching copper and cyanide leaching process reveals the formation mechanism of silver occlusion. On this basis，study the mechanism of phase-reconstruction by acid fluoride salt system, characterization microstructure, phase composition and reconstruction system’s chemical composition of ore material before and after phase-reconstruction and deduce evolution law of gold and silver in phase-reconstruction process. Then Reveal the mechanism. Determinate reaction constant and set up the reaction kinetics model of phase-reconstruction process. Compare the phase-reconstruction results of different system and determine the effect law of phase reconstruction conditions on the silver leaching rate. Based on the above research, form technical prototype of phase-reconstruction to effective improve silver recovery rate from complex gold ore by roasting pretreatment process, and provide theoretical and technical support for efective development and utilization of refractory gold resource. Which can improve the core competitiveness of China's gold and silver smelting industry.

复杂金矿焙烧氰化过程中，银物相发生迁移，形成硅酸盐和铁酸盐等包裹，导致银浸出率仅为50%左右。现有研究多着眼于焙烧工艺改进、焙烧添加剂的遴选和氰化工艺的优化，而对形成银包裹的机理研究较少。本课题通过研究焙烧过程热力学，系统研究氧化焙烧-酸浸分铜-氰化浸出过程中银赋存状态传递、迁移和演化过程规律，揭示形成银包裹的机理；在此基础上，开展酸性氟盐体系物相重构机理研究，表征物相重构前后物质的微观结构、物相组成和重构体系化学组成，推导强化物相重构过程金、银的物相重构演变规律，揭示物相重构过程机理；测定物相重构过程反应常数，建立反应动力学模型；比较不同体系的物相重构结果，确定物相重构条件对银浸出效果的影响规律。基于上述研究，建立有效提高复杂金矿焙烧预处理工艺银回收率的物相重构技术原型，为难处理金矿资源的高效开发利用提供理论与技术支撑，提高我国金、银冶炼行业的核心竞争力。

复杂金矿焙烧预处理过程中，银物相发生转变，形成硅酸盐和铁酸盐等包裹，导致银浸出率仅为50%左右。研究发现：未使用添加剂直接焙烧时，焙砂中硅酸盐包裹金为4.38%（原矿为4.45%），焙砂中硅酸盐包裹的银为37.54%（原矿为12.28%），氧化银含量为29.24%。使用添加剂焙烧后，焙砂中硅酸盐包裹金降低到0.40%，硅酸盐包裹的银降低到9.25%，氧化银含量升高到48.59%。氰化渣中金银的变化趋势与焙烧过程保持一致，使用添加剂焙烧，氰化渣中硅酸盐包裹的金银含量显著降低。说明多复杂金精矿焙烧预处理时使用添加剂氢氧化钠，可以有效降低硅酸盐对金银的包裹，同时有利于氧化银的生成。提高氧分压，硫酸化焙烧进行更充分，从而可以获得更高的金银铜的提取率，在较优焙烧条件下，金银铜的浸出率分别可达91.23%、75.12%、91.23%。. 复杂金矿氟盐预处理热力学及物相变化研究表明，现有工艺酸浸分铜过程中，铁的氧化物会发生部分溶解，而SiO2难以溶解；向体系中添加氟盐以后，可以促进铁氧化物和SiO2的溶解，强化对致密包裹物的侵蚀作用，但需要较好地控制体系酸度和操作温度。经过氟盐预处理后颗粒表面的金、银含量均有所上升，石英矿物表面的银和金含量分别由原来的0.03和0.01上升到1.29％和0.29％；赤铁矿物表面的金和银含量分别由原来的0.00和0.00上升到1.55％和0.16％；石英与赤铁矿混合复杂矿物表面的金和银含量分别由原来的0.06和0.02上升到1.13％和0.64％。表明金银得以暴露，有利于提高后续金银氰化浸出率。经过氟盐预处理，矿石表面发现部分与含铅矿相结合的金银，可能是铅矿石矿物与金、银以类质同象形式存在。. 氟盐预处理-氰化浸出金、银过程符合JMA动力学模型，金、银浸出的表观活化能分别为19.15 kJ/mol和16.00 kJ/mol，反应受内扩散控制。