FLSmidth, is working on the rapid oxidative leaching technology designed to operate at 80C and normal atmospheric pressure. Those characteristics make it safer than traditional smelting – the ROL process is both faster and simpler.

The technology managed to beat out an entry from NASA to win the global R&D 100 Award.

ROL can leach more than 98% of the copper from chalcopyrite concentrates in fewer than six hours. Existing atmospheric leach processes leach a maximum of 95% copper in 20 to 60 hours. Because it has faster throughput, mines can get away with having a smaller, less power-intensive plant.

A pilot plant at FLSmidth’s Utah research facility includes four scaled reactors that enable batch and continuous operation of the ROL process.

At the moment 10 litre and 100l continuous stirred tank reactors in series with stirred media reactors are being used to test the process in batch leaches. They have delivered encouraging results.

Stirred media reactors are used to mitigation passivation of the chalcopyrite copper concentrates. This passivation is where an oxide coating forms and “protects” the ore from processing.

Included with each apparatus is equipment used in measurement and control of temperature, pH, Redox potential and oxygen addition as well as a tracking system.

The ROL process uses a mechano-chemical leach to overcome passivation.

FLSmidth aims to deliver a pregnant liquor solution that will match reagents being developed by chemical companies to maximise the potential yield from hard to process and arsenic-laden concentrates.

For copper producers this could mean a renewed business case for remaining deposits at several existing mines that have lost the ability to economically make copper concentrates suitable for smelting.

ROL also makes it possible to develop mineral deposits containing arsenic for recovery of copper, gold and silver while complying with stringent environmental regulations.

It could help such mines avoid the potential for arsenic contamination of sea, air and land during transport to a smelter or as a consequence of the smelting process.

FLSmidth minerals division group executive vice-president Manfred Schaffer said the technology would deliver economic and productivity benefits to the copper sector.

“Many existing mines are holding tonnes of copper concentrate with more than 0.5% arsenic concentrations, which is too high for smelting,” he said.

“Our technology can be used to process those tonnes of high-arsenic concentrate into saleable product or even make it possible to develop new deposits that are high in arsenic.”

For copper producers the technology could mean a renewed business case for remaining deposits as several existing mines have lost the ability to make copper concentrates suitable for smelting.

ROL technology is designed to make it possible to recover copper from low to mid-grade concentrates.

According to FLSmdith there are also known mineral deposits that are unsuitable for smelting but may be suitable for leaching with ROL.