Giant leap in copper leaching technology

The top ore layer of an open pit copper mine is easily processed using heap leach in tandem with solvent extraction and electrowinning to produce copper cathodes. The copper mineral most predominate in mines is however chalcopyrite (CuFeS2), a refractory sulfide mineral that is found deeper in the mine. Consequently, mining companies struggle to maintain copper production during the transition from oxide ore to sulfide ore as open pit mines reach the later stages of development. Mining companies also struggle to recover the copper from very low-grade concentrates and from concentrates contaminated with arsenic.

FLSmidth recently filed patents for a new hydrometallurgy process called the FLSmidth® Rapid Oxidative Leach that can economically remove the passivation layer of primary sulfides and thereby allow the extraction of copper. The technology operates at atmospheric pressure and temperature around 80 °C, making it possible to leach directly at the mine and hence provide a seamless transition from oxide ore to sulfide concentrates.

While existing atmospheric leach processes leach a maximum of 95 % copper in 20-60 hours, the FLSmidth® Rapid Oxidative Leach process can leach more than 98 % of ­copper from concentrates containing as low as 8 % copper in less than 6 hours; a faster and much simpler process. And that, as Head of Group R&D, Jens Almdal, points out is a giant leap in productivity improvements: “For a copper mine with remaining low quality copper deposits producing around 200 000 tons of copper per year, our 3 % output increase would mean an extra US$ 40 million per year with a copper price around US$ 6600 per ton. That is indeed a significant contribution to profitability in an industry that normally chases 0.1-0.2 % increase in copper recovery by design modifications of flotation machinery,” Jens Almdal states.

For copper producers, the new technology could mean a renewed business case for remaining deposits: several existing mines have lost the ability to make copper concentrates suitable for smelting. The FLSmidth® Rapid Oxidative Leach 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 with the new technology would be suitable for leaching.

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 mine to smelter.

“A lot of existing mines have piles of copper concentrate with more than 0.5 % arsenic concentrations which is too high for smelting. 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,” explains Manfred Schaffer, President, Minerals division. FLSmidth has patents pending for the new technology and a cooperation initiated with two customers with the technology expected to be implemented in large scale in 2017.

//www.flsmidth.com" target="_blank" >www.flsmidth.com:www.flsmidth.com

x

Related articles:

New research project ReAK for the reduction of arsenic in copper concentrates

With 27 % of the global production, Chile is the largest producer and the world´s largest exporter of copper. This makes copper mining one of the country’s most important export revenues. However,...

more

New research project ReAK for the reduction of arsenic in copper concentrates

With 27 % of the global production, Chile is the largest producer and the world´s largest exporter of copper. This makes copper mining one of the country’s most important export revenues. However,...

more
Issue 05/2011

Safety first in mining

Renaissance of heap leaching for valuable metals

1?Introduction Heap leaching is the term used for hydrometallurgical extraction processes in which crushed and ground ore is heaped up and then sprayed with an aqueous chemical solution in order to...

more
Issue 01-02/2013

Key technology for efficient copper ore processing

The mine operator CUDECO is banking on innovative allmineral technology for processing their native copper. As of mid 2013, the Chinese state company ­SINOSTEEL will bring into operation ten jigging...

more
Issue 12/2023 Reduced environmental impact

Sensor-based sorting of sulfide ores

The increase in global demand for copper, zinc and lead poses a challenge for mining operations: increasing their efficiency and productivity to meet the demand while ensuring their profitability and...

more