Understanding the role of catalysts in the leaching of sulfide minerals

黄铜矿是世界上储量最丰富的铜矿，约占世界铜总产量的70%。大多数黄铜矿精矿都是用熔炼法处理的。然而，冶炼厂会释放二氧化硫气体（酸雨的主要原因），无法处理砷（许多铜矿体中的常见元素）等杂质，而且通常距离铜矿非常遥远（产生高昂的运输费用并导致温室气体排放）。浸出是一种很有前途的冶炼替代方法。浸出不排放气体，可以以环境敏感的方式处理砷，可以应用于低品位的材料，并且可以直接在矿山进行操作。然而，黄铜矿是所有硫化物矿物中最难浸出的，因为在典型的氧化浸出条件下，黄铜矿往往会形成被动层。多年来已经开发了许多方法来克服这种被动性，依靠超细研磨，高腐蚀性化学添加剂（如氯化物）和/或高温高压的组合来确保快速浸出。然而，事实证明，大多数技术成本太高或太复杂，无法在工业上实施，而且没有一种技术取得了广泛的商业成功。最近，UBC开发了一种新的浸出原生铜精矿的方法，该方法基于使用廉价的催化剂（如黄铁矿和活性炭）来加速黄铜矿在大气条件下在轻度腐蚀性硫酸盐溶液中浸出的速度，而无需精细研磨或化学添加剂。这些催化剂也被证明对铝辉石的处理是有效的，铝辉石是一种高度难熔的铜砷硫化物矿物，在经济上越来越重要，不适合冶炼。最近，我们发现在浸出之前用微量的溶解银预处理黄铁矿样品可以显著提高其作为催化剂的有效性。该研究的目的是了解黄铁矿和活性炭对原生硫化铜的催化作用的机制，并将这一理解应用于工业上稳健的浸出过程的开发。

Chalcopyrite is the world's most abundant copper mineral, accounting for roughly 70% of the world's total copper production. Most chalcopyrite concentrates are processed by smelting. However, smelters release sulfur dioxide gas (the leading cause of acid rain), cannot handle impurities such as arsenic (a common element in many copper orebodies), and are typically very remote from copper minesites (incurring high shipping charges and contributing to greenhouse gas emissions). Leaching presents a promising alternative to smelting. Leaching emits no gases, can handle arsenic in an environmentally sensitive manner, can be applied to low grade materials, and can be operated directly at minesites. However, chalcopyrite is among the most difficult of all sulfide minerals to leach, as it tends to form passive layers under typical oxidative leaching conditions. Many processes have been developed over the years to overcome this passivity, relying on a combination of ultrafine grinding, highly corrosive chemical additives (eg, chloride), and/or high temperatures and pressures to ensure rapid leaching. However, most have proven too costly or too complex for industrial implementation, and none have achieved broad commercial success. Recently, a fresh approach to leaching primary copper concentrates has been developed at UBC, based on the use of inexpensive catalysts such as pyrite and activated carbon to accelerate the rate of chalcopyrite leaching under atmospheric conditions in mildly corrosive sulfate solutions, without fine grinding or chemical additives. These catalysts have also proven effective for the treatment of enargite, a highly refractory copper-arsenic sulfide mineral of increasing economic importance which is unsuitable for smelting. Most recently, we have discovered that pretreating pyrite samples with miniscule quantities of dissolved silver prior to leaching dramatically enhances their effectiveness as catalysts. The objective of the proposed research is to develop an understanding of the mechanisms underlying the catalytic effects of pyrite and activated carbon on primary copper sulfides, and to employ this understanding in the development of industrially robust leaching processes.