12 Jan Australian Researchers Improve Gold Mining Process

Members of Curtin University in Perth, Australia, have recently perfected the technique for glycine leaching. It will aim to improve the gold extraction process. From an environmental point of view, the method will be more environmentally friendly by not using cyanide.

Researchers at Curtin University in Australia have improved their award-winning glycine leaching technology by significantly increasing the leaching rates of gold ore, using a low concentration of a strong oxidizing agent known as potassium permanganate.

The research, published in Hydrometallurgy and led by Professor Jacques Eksteen and Dr. Elsayed Oraby, both from WA (Western Australia) from the Minerals, Energy and Chemical Engineering school at Curtin University, found that adding potassium permanganate to the process could solve the problems currently associated with glycine leaching of gold (in the absence of cyanide), such as the need for higher temperatures, glycine concentrations, and oxygen addition levels.

Professor Eksteen reported that the research team evaluated various oxidants for their new glycine alkaline gold leaching system, the most satisfactory results where seen with potassium permanganate.

Eksteen said: ‘Traditionally, the leaching or separation of gold and other precious metals from a mineral deposit or electronic waste materials requires the use of cyanide, a highly toxic chemical compound known to have detrimental effects on the environment and on the human body.”

“Industrially, it is very expensive to detoxify cyanide, and it still does not eliminate the risks associated with the transportation, handling and processing of the chemical.”.

Professor Eksteen said that glycine is naturally produced by the human body and is essential for life, while cyanide, on the other hand, is dangerous for life, as he mentioned in a previous quote.

“Permanganate and glycine partially break down to form insoluble manganese dioxide, insoluble calcium oxalate and nitrogen, all of which are naturally low toxicity chemicals. While cyanide retains its toxicity, even in the waste solution from the extraction process’ said Professor Eksteen.

Eksteen noted that the research team added low concentrations of potassium permanganate to the alkaline glycine system, which resulted in the leaching of 85.1% of the gold from the mine deposit (similar to cyanidation extraction) at room temperature and using a substance known as a benign reagent.

Dr. Elsayed Oraby said the new process builds on Curtin’s significant work in this area, which has been ongoing for the past eight years.

Oraby said: “Researchers at Curtin University have spent years developing a new leaching process and our work expands the use of this proprietary technology, making it more suitable for the extraction of gold deposits.”

“We believe that this new process will bring many benefits to gold mining industries, which from an environmental point of view is a much friendlier extraction method.”

To commercialize the new process, the Curtin University team is working with mining industry partner, Mining and Process Solutions (MPS)..

Source: World Energy Trade.