Mining Process
The company has three concentrators, two at Nchanga and one at Konkola.
The two Nchanga concentrators (East mill and West mill) were recently modernized. A new concentrator was commissioned at Konkola in 2008.
The Nchanga smelter was commissioned in 2008, incorporating technology from Outotec, Finland. The smelter processes ore from Konkola, Nchanga and other third party concentrates and it has a capacity of 311,000t pa. The smelter has met global benchmark environmental performance as it captures 99.6% of sulphur emissions. The main refinery at Nkana uses electrolysis to process copper anodes to LME A grade copper cathodes. It has been expanded to accommodate the increased anode production from the Nchanga smelter.
The Nchanga Tailings Leach Plant (TLP), one of the largest of its kind in the world, processes tailings from the Nchanga concentrators and stockpiled tailings to produce copper. The TLP extracts copper directly to cathodes from concentrate solution using electrolysis. Since inception of the mine, refractory ore from the copper production process was surface stockpiled. KCM has now developed a process to extract copper from the refractory ore stockpile.
The company also produces several by-products, including sulphuric acid produced from the smelting process, which is largely consumed in the leaching process. The new Nchanga smelter also has the capability to recover cobalt from copper concentrates. The cobalt which comes in the form of a copper-cobalt alloy is sold to markets mainly in Asia. A final by-product of the refinery process is slime which is also exported.