Atmospheric oxidation of pyrite; maximizing the elemental sulphur yield

本课题主要研究黄铁矿难处理矿石的大气预处理及金回收。从简单矿石中提金的典型方法是将矿石浸在稀释的氰化物溶液中。难浸金矿石的浸出比简单矿石更为复杂。通常，金矿的难熔性是由于硫化物的存在，如黄铁矿（FeS2）。在难选矿石中，细小的金颗粒通常被包裹在硫化物基体中，难以被氰化物溶液接触，导致金的回收率较差。难处理金矿的处理还需要一个额外的步骤，即氧化预处理，以分解硫化物结构并释放被包裹的金颗粒。然而，硫化物，如黄铁矿，是非常稳定的，它们的分解需要强氧化条件。焙烧和压力氧化是两种经商业验证的硫化物氧化技术。然而，建立一个基于这些工艺的新工厂可能是非常昂贵的。此外，如果进料矿石含有重金属元素，如砷，那么焙烧过程可能会将这些元素释放到环境中。惩罚元素是剧毒的，它们释放到环境中的风险限制了焙烧过程的应用。本提案将研究一种常压浸出法用于黄铁矿氧化。目标是开发一种具有高氧化动力学和高元素硫产率的工艺。该过程的动力学应该很高，以使该过程的经济性合理。应用碳基催化剂可获得较高的氧化动力学。为了消除过量的硫酸生成，实现高单质硫产量也很重要。通过巴里克黄金公司最近商业化的工艺，将氧化材料的金浸出在硫代硫酸盐溶液中进行。6名HQPs（2名博士和4名暑期学生）将参与该项目，并将获得广泛的萃取冶金知识。hqp将接受培训，以满足加拿大采矿业的需要。

This research proposal is about atmospheric pre-treatment and gold recovery of pyrite-refractory ores. Thetypical method for gold extraction from simple ores is to leach the ore in a dilute cyanide solution. Leaching ofthe refractory gold ores is more complex than simple ores. Typically, the refractoriness of the gold ores is dueto the presence of sulphides, such as pyrite (FeS2). In the refractory ores, fine gold particles are usuallyencapsulated in the sulphide matrix and are inaccessible to cyanide solution, resulting in poor gold recoveries.Treatment of the refractory gold ores requires one additional step in the process, known as oxidativepre-treatment, to decompose the sulphide structure and liberate the encapsulated gold particles. However,sulphides such as pyrite, are very stable and their decomposition requires strong oxidizing conditions. Roastingand pressure oxidation are two commercially-proven technologies for oxidation of sulphides. However,building a new plant based on these processes can be extremely costly. Additionally, if the feed ore containspenalty elements, such as arsenic, then the roasting process may release these into the environment. Penaltyelements are highly toxic and the risk of their release into the environment limits the roasting processapplication.This proposal will investigate an atmospheric leaching method for pyrite oxidation. The goal is to develop aprocess with high oxidation kinetics and high elemental sulphur yield. The kinetics of the process should behigh to make the economics of the processes justifiable. The high oxidation kinetics will be obtained byapplication of carbon based catalysts in the process. High yield of elemental sulphur is also important toachieve, in order to eliminate excess sulphuric acid generation. Gold leaching of the oxidized material wouldbe performed in thiosulphate solution by the recently commercialized process by Barrick Gold Corp.Six HQPs (2 PhD and 4 summer students) will be engaged in this project, and will gain extensive knowledgeof the extractive metallurgy. The HQPs will be trained to meet the needs of the Canadian mining industry.