Addressing the 2019 South Australian Exploration and Mining Conference today in Adelaide, Australia, Environmental Copper Recovery (ECR) said it hoped the company's drive to bring new commercial mining to the former Kapunda copper mining precinct would demonstrate ISR as an economic and socially acceptable form of copper and gold recovery from stranded resources.
The company has just completed successful drilling to carry out further hydrogeological and mineralogical testing in the last two weeks under a broader ISR research initiative. This initiative has reportedly attracted leading minerals, land and water, geophysics and mining engineering scientists to the landmark work.
ISR, also known as in-situ leaching (ISL) or solution mining, is a mining process used to recover minerals such as copper and uranium through boreholes drilled into a deposit, in situ. It works by artificially dissolving minerals occurring naturally in a solid state.
The process initially involves the drilling of holes into the ore deposit. Leaching solution is then pumped into the deposit where it makes contact with the ore. The solution bearing the dissolved ore content is then pumped to the surface and processed.
This process allows the extraction of metals and salts from an orebody without the need for conventional mining involving drill and blast, open-pit or underground mining.
Leon Faulkner, managing director of ECR, told delegates: "We are hopeful that the research outcomes at Kapunda may help Australia develop technologies applicable to the ISR of copper and other metals.
"Broader adoption of this extractive method can potentially lead to significant benefits for the mining industry, particularly as a much safer and more environmentally acceptable way of extracting profitable mineralisation from ore bodies currently not economical for conventional mining or facing social licence operating issues."
ECR has concentrated the research work at the Kapunda project to optimise fracture and flow modelling, selection of lixiviant (a liquid medium used in hydrometallurgy to selectively extract the desired metal from the ore or mineral) and addressing modern day environmental and social issues.
Faulkner said that a large selection of potential substances to extract Kapunda's remaining copper and gold reserves was under assessment. "At the end of the day, we want a lixiviant that works with existing groundwater rather than to drastically try to modify it," he explained. "Our test programme is looking at the full range of acid, neutral and alkaline substances and all the pros and cons of the pH range they cover.
"This includes testing with different lixiviant options because they have the propensity to recover metals other than copper (including gold) which is present in a currently unknown amount in the Kapunda deposit.
"Although our initial field samples showed relatively low concentrations of gold, measurable quantities turned up in the leach liquors."
Soil sampling work around the old mine site shows increased copper values in soil, while water sampling shows the water in the mine area is salty, has low pH and is high in copper.