ALTERNATIVES For the past 15 years, other research groups have persisted with resin based variants of the Vitrokele process, but no commercial process has eventuated. There has been a similar focus on finding alternatives to cyanide, in the hope they will be more environmentally acceptable. Again nothing has emerged as a serious contender. So what is the answer? Simply accept cyanide as the superior solvent and address the concerns: Hence, the RECYN process. COMMERCIALISATION OF THE RECYN PROCESS Finding an alternative to cyanide is like bashing your head against a brick wall: You get a sore head. To find a more specific gold adsorbent is like kicking the wall, less painful, but does not solve the main problem. GreenGold has taken a different approach by bypassing the wall. Carbon is satisfactory for metal recovery in most cases, so it is better to focus on the real problem, which is the negative reputation and impact of cyanide. The RECYN process totally solves this problem, reducing operating costs and increasing revenue. By turning the technology around and focusing on cyanide recovery and detox elements, the true value of the resin process can be realized. For the time being, gold and silver recovery is left for carbon: The two processes cannot be carried out simultaneously. The crucial step is commercialization. Many laboratory processes do not translate practically or economically to the real world. Even if they are heralded as definite winners, it still takes a willing mining company to take the risk of serious financial, environmental and social impact in the event of failure. Many fledgling technologies stumble at this crucial phase. As noted above the core technology has a long history of development, with varying degrees of success in commercial application. The reasons for the initial failures are well understood and building on the successes has been the way forward. The following case histories demonstrate the relative maturity of the RECYN process, although it still needs to be implemented commercially over a much wider spread of ore types to be considered a standard part of the gold process flow sheet. In addition to the examples below, there is an increasing pipeline of projects considering implementing the RECYN process for their existing operations to replace conventional detox methods. The Mirah Project Engineering companies are entrusted with the task of designing and constructing process plants reflecting the best available technologies. In this capacity, they have an advantage in persuading mining companies to implement new technology to enhance project economics. Historically a major risk was arguably borne by the engineering company, especially when undertaking lump sum projects with performance guarantees. This was the case with the Signet’s Mirah gold/silver project, a 1Mtpa project built in 1998 for $13M. Depressed gold prices in the early 90’s were not favourable for the Mirah Project, which was relatively low grade (2.3g/t Au), high silver (70g/t Ag), low Reserve (250koz) and very high strip ratio (15:1). The feasibility study showed a marginal project, which on balance was not attractive for funding. Introducing a cyanide recovery process with economic detoxification allowed the Mirah project to get across the line and become an economic proposition.
ALTA 2017 Gold-PM Proceedings
4
Powered by FlippingBook