Atmospheric oxidation of pyrite; maximizing the elemental sulphur yield

本课题是关于难选硫铁矿石常压预处理回收金的研究。从简单矿石中提取金的典型方法是在稀氰化物溶液中浸提矿石。难浸金矿石的浸出比简单金矿石复杂。通常，金矿石的耐火性是由于硫化物的存在，如黄铁矿（FeS2）。在难处理金矿石中，微细的金颗粒通常包裹在硫化物基质中，氰化物溶液无法接触到，导致金的回收率很低。处理难处理金矿石需要一个额外的步骤，称为氧化预处理，以分解硫化物结构并释放包裹的金颗粒。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。焙烧和加压氧化是两种经过商业验证的硫化物氧化技术。然而，基于这些工艺建造新工厂的成本可能非常高。此外，如果进料矿石含有砷等元素，那么焙烧过程可能会将这些元素释放到环境中。由于硫铁矿中的微量元素具有很强的毒性，且其释放到环境中的风险限制了焙烧工艺的应用，因此本研究将探讨一种常压浸出法氧化硫铁矿的方法。目标是开发一种具有高氧化动力学和高元素硫收率的工艺。该过程的动力学应该是高的，以使该过程的经济合理。采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，元素硫的高产率也很重要。氧化物的金浸出将在硫代硫酸盐溶液中通过巴里克黄金公司最近商业化的工艺进行。六名HQP（2名博士和4名暑期学生）将参与该项目，并将获得广泛的提取冶金知识。将对HQP进行培训，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.