HEAP LEACH – SX / EW n Both glycine and sodium hydroxide( used to maintain alkaline conditions) are regenerative in the process so that reagent consumption is low. MPS Technical Director, Frank Trask observed that it is a simple process that requires no new equipment to be designed, has low operating costs due to regeneration of the principal reagents, and is expected to provide high copper recoveries with almost all copper minerals even chalcopyrite; long considered the‘ Holy Grail’ of copper leaching. It will also offer the gold industry a non-toxic method of leaching gold, something that is becoming more important in many jurisdictions around the world.
MPS and Curtin have more recently developed a proprietary GlyCat™ leaching technology for gold-copper ores. In conventional gold heap leaching, quite low copper grades can dramatically increase cyanide consumption, often rendering the project uneconomic. Conversely, any gold present in copper ores is completely lost in acid heap leaching. GlyCat offers a way around these long standing problems by concurrently leaching both copper and gold in an alkaline glycine cyanide solution. The process economics get a triple boost; higher revenue from recovery of both metals, lower overall reagent cost, and potentially lower capex as a result of accelerated leach rates.
MetaLeach and DEMET
Alexander Mining PLC is pleased to report that it has received notification that its MetaLeach subsidiary has been granted a patent for a Method for Leaching Zinc Silicate Ores in Australia.
Martin Rosser, Chief Executive Officer: " The granting of our Zinc Silicate Leaching Patent in Australia is most significant. Zinc silicate mineralisation comprises a significant proportion of nonsulphide zinc ores targeted for use by our AmmLeach ® process and this is the first patent to be granted for this particular leaching method patent family."
Also in Australia, MetaLeach has executed a licence agreement with Accudo Metals, a new Australian company which has been established to exploit Alexander ' s proprietary leaching technologies. It is funded by investors and clients of BlueMount Capital, a national midtier Australian investment bank. Prefunding for test work and a full scoping study on the first targeted opportunity has been committed.
Subject to the study being positive, Accudo foundation funders and BlueMount clients will fund a detailed feasibility study.
MetaLeach has granted Accudo an exclusive licence for up to five mining projects in Australia to use its leaching technologies.
Rosser said:“ Accudo is well financed and intent upon rigorously evaluating the use of Alexander ' s leaching technologies in Australia. We have been in detailed discussion with them about a range of identified potential projects of interest and we look forward to developments with optimism.”
Accudo director Saliba Sassine said:“ Accudo is pleased to have entered into this groundbreaking agreement for both parties. The company is excited about the prospects and testing the technology on targeted ores."
Pursuing a philosophy of treatment without chemicals, Blue Planet Strategies( BPS) continues to advance its innovative and versatile proprietary DEMET™( Dynamic Electrolytic Metals Effluent Treatment) platform technology and process suite.“ Electricity; rather than chemicals, is used to adjust target stream parameters in a variety of desirable ways to offer an unprecedented range of treatment options that can be tailored to site-specific needs,” explains Patrick James, BPS President / CEO. DEMET treatment serves to recover valuable products, clean the target stream, or control target stream chemistry to improve overall
process efficiency / stability or extract value from bleeds or waste water prior to final treatment for discharge or reuse and potentially extend production to the use of marginal / waste grade ores.“ Treatment is cleaner, often cheaper, and can recycle key consumables and / or provide new revenues via recovery of components now lost,” says James.
Originally developed to either directly electrowin or concentrate metals from weak PLS to enable production from waste-grade ore, difficult to leach ore, or tailings, DEMET continues to rapidly demonstrate new functionality.
DEMET treatment can target a variety of mining influenced waters( MIW), including both hydrometallurgical sources like weak leach streams, raffinates, bleed streams, or drain down waters and pyrometallurgical sources like smelter / refinery blow down waters, electrorefining bleeds, and forming / descaling / casting operations dragout and spent solution treatment.
In PLS and raffinate treatment, DEMET can target residual metals and / or acid recovery or concentration, control of pH or interfering iron concentrations, sulphate removal and selective recovery of valuable leached components. The latter can include the target ore metal and other common major PLS / MIW contaminants as enhanced value products.
“ DEMET implementation capitalises on advanced design features that provide low energy consumption, high operation rates for compact footprints, and resist fouling and dendritic shorting which often challenge conventional electrolytic cells,” James says.
A recent application focused on tailoring the chemistry of a leach raffinate stream for a top tier copper producer using heap leach processing. Cost-effective raffinate treatment of a high TDS raffinate bleed stream to adjust solution chemistry without creating solids was targeted to enhance production. The primary treatment goal was stream pH and targeted iron level adjustment to customer specifications with acid recovery as a secondary goal. Scoping work indicated DEMET treatment feedstock costs of ~ 60 % that of conventional lime treatment( electricity for DEMET versus lime-CaO for conventional neutralisation) for target neutralisation and that product acid solutions up to 6 % sulphuric acid could be directly generated using DEMET. A low capacity(~ 1 / 2,000th flow)
NOVEMBER 2016 | International Mining 27