New gold extraction method both cheaper and faster

Scientists have developed a new method for extracting gold that reduces the cost of production of the precious metal by up to 40 per cent and dramatically decreases the amount of time needed to do so.

Researchers, including those from National University of Science and Technology MISIS (NUST MISIS) in Russia, developed the technology that replaces the traditional and most widespread technology in Russia of using direct cyanidation for extracting gold from oxidised copper ores. They used ammonia-cyanide leaching to extract gold from mines, which was four to eight times faster than the traditional method. The technology also reduces the negative impact of copper on the degree of the target component, so the separation of metal compounds is more efficient in comparison to the traditional technology, researchers said.

The main problem of the traditional technology is the long process - about 100-120 hours. In addition, copper often dilutes the gold extract and due to that the degree of the precious metal remains relatively low, despite the high cost of production, researchers said. The cost of about 28 grammes of gold obtained by using direct cyanidation from similar ores could reach USD 800, which is economically not viable since an ounce of gold on the stock exchange is worth USD 1200, researchers said. The new technology reduced the cost of production by 30- 40 per cent.

"The technology based on the process of ammonium cyanide is still being developed, so the possibility to introduce our technology into gold production will be affected by world market prices for an ounce of gold," said Vadim Tarasov, Professor at NUST MISIS.

"Of course, there are even more efficient technologies available which would extract all the gold from ore, but they cost colossal amounts of money, so their introduction into production remains impractical even today," Tarasov said.

"The possibility to introduce our technology into gold production will be affected by world market prices for an ounce of gold," Tarasov said.

Pilot testing of this method was carried out in the Tarror gold mine located in Tajikistan. The upper levels of the Tarror mine contain a significant amount of copper.

Scientists tried to remove it with various technologies developed in research labs, but all the methods tuned out to be economically inefficient. However the technology on the basis of ammonium cyanide proved up to the task, researchers said.