Maximizing copper recovery with innovative ROL technology

FLSmidth recently signed a joint agreement with BASF to expedite the commercialization of the new FLSmidth® Rapid Oxidative Leach process. Originally announced to the mining industry back in May, our combined teams continue to develop this exciting breakthrough technology. 

The Minerals laboratory team tests FLSmidth® Rapid Oxidative Leach processes with a strirred media reactor

The Minerals laboratory team tests FLSmidth® Rapid Oxidative Leach processes with a strirred media reactor

The FLSmidth® Rapid Oxidative Leach (ROL) process is receiving a lot of attention in the media. Considered by many as a revolutionary technology, patents are already pending. The ROL process targets difficult-to-process copper concentrates, such as primary sulphides and concentrates containing high levels of arsenic. ROL enables the industry to dissolve copper from low- to mid-grade concentrates at 80oC. This makes it possible to leach directly at the mine, safely extracting the copper and maximizing the use of existing capacity during the transition from oxide ore to sulphide ore concentrates.

ROL becomes a more efficient and profitable alternative in place of selling the concentrate to smelters for removal of the arsenic and extraction of the copper. 

BASF, a world-leading chemical company, has operated in the copper industry for years supplying chemical reagents and expertise to mineral processing plants around the globe. They saw the ROL process as an exciting opportunity for hydrometallurgical processing advancements, especially now that copper ore grades are declining and more companies are having to turn to higher-grade copper ore deposits containing arsenic.

ROL pilot plant being installed in Utah, USA

ROL pilot plant being installed in Utah, USA

"Several years ago, we focused on developing chemicals that would support the industry's inevitable move towards mining more complex ores; chemicals that required a new leaching technology," said Christian Lach, Vice President of Strategic Marketing and Innovation for Water, Oilfield and Mining Solutions at BASF. "We believe that the FLSmidth Rapid Oxidative Leach process combined with BASF's novel reagents is the game changer that will enable the copper industry to process such ores." 

Our joint R&D project with BASF is now underway, with a pilot plant facility being built onsite at FLSmidth’s Minerals division headquarters located in Salt Lake City, USA. The new lab will include four scaled reactors which enable batch and continuous operation of the ROL process. Currently 10-liter and 100-liter reactors are being used to test the process in batches and have provided very promising results. These specialized Stirred Media Reactors (SMRt) are used to mitigate passivation of the chalcopyrite copper concentrates. Included with each apparatus is equipment used in measurement and control of temperature, pH, REDOX potential and oxygen addition, as well as a sample tracking system.

Stirred media reactor test equipment

Stirred media reactor test equipment

The ROL process uses a chemical-mechano leach to overcome passivation. FLSmidth aims to provide a pregnant liquor solution that will match up to the simultaneous research that BASF is undertaking at their Tucson, USA laboratories. BASF’s testing includes incorporating innovative solvent extraction reagents, which exhibit high resistance to degradation and an increased change in copper selectivity.

While existing atmospheric leach processes leach a maximum of 95% copper in 20–60 hours, the ROL process can leach more than 98% of the copper from concentrates containing as low as 8% copper in less than six hours—a faster and much simpler process.  

Complete mineral characterization is available at FLSmidth’s Minerals Technology Center and is used to examine both concentrates and leach residues. Elemental analysis of solutions and leach residue is also available to complete mass balances of all batch leaches. FLSmidth has developed comprehensive test procedures that have allowed replication of the previous batch leaches, and in the coming months is preparing to test with the new pilot plant for continuous operation of the ROL process.

Analyzing samples from ROL process

Analyzing samples from ROL process

In addition to this joint R&D project with BASF, FLSmidth is already in cooperation with four customers—with additional interested customers lining up to discover the exciting opportunities this process will reveal. FLSmidth is expecting to implement the ROL technology in large scale at a customer site in 2017.

For copper producers, the new 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. This ROL technology makes it possible to recover more copper from low-grade concentrate. Also, there are mineral deposits yet to be developed that are unsuitable for smelting, but would be suitable for leaching with the new technology.

The new technology also makes it possible to develop mineral deposits containing arsenic for recovery of copper, gold and silver, while complying with stringent environmental air and land pollution regulations. As the new technology operates at atmospheric pressure, a concentrate can be treated at the mine location with complete control over the arsenic-bearing residues generated after leaching. This makes it possible to avoid the potential of arsenic contamination of sea, air and land while en route from the mine to the smelter. 

"A lot of existing mines have piles of copper concentrate with more than 0.5% arsenic concentrations, which is too high for smelting," said Manfred Schaffer, President of FLSmidth's Minerals Division. "Our technology can be used to process these piles of high-arsenic concentrate, or even make it possible to develop new mineral deposits high in arsenic."   

CONTACT: Ron Klepper