The Mutanda copper-cobalt deposit lies with the lower part of the Neoproterozoic Katangan sedimentary succession which extends over more than 700 km from Zambia through the Katanga province of the DRC and is up to 150km wide. It is part of a thrust-and-fold belt known as the Lufilian Arc. It shares the same characteristics of most of the deposits within the Copperbelt in that it is stratiform and associated with carbonate or carbon-rich lithologies (Cailteux, et. al. 2005).

The main copper oxide minerals present are malachite and pseudomalachite, with heterogenite, the main Cobalt mineral. Quartz and chlorite dominate the gangue component in all the samples.

The sulphide minerals have yet to be subjected to a laboratory mineralogical analysis.

The mining method applied is conventional open pit mining, consisting of drilling, blasting, loading and hauling.

The concentrate operations consist of a crusher, a small dense media separator plant, and a spiral plant. These operations produce more than 20,000 metric tons each year. The two older Mutanda copper plants consist of four tank houses, commissioned between September of 2010 and January 2012. They use two-stage metallurgical process of solvent extraction and electro winning to process a combined 110,000 metric tons of copper each year. The expansion completed at the end of 2013 included the addition of:
· Increasing crushing, milling, leaching and CCD capacity to 200 ktpa (kilo-tonnes per annum) at design feed grades.
· 54 ktpa HG SX and 46 ktpa LG SX.
· Adding Electro winning sections EW5 to EW7 of 30 ktpa each.

The sulfuric acid and liquid sulfur dioxide plant was commissioned in early 2012 and has an expected daily capacity of 390 MT of sulfuric acid and 73 MT of liquid sulfur dioxide. The production of sulfur dioxide – a reagent used in cobalt leaching, enables significant savings in reagent costs.

The ROM ore will be tipped into a ROM tip bin equipped with a static grizzly which will ensure that oversize material will not report to the primary crusher (oversize material can choke the crusher). Ore will be withdrawn from the ROM tip bin using a variable speed apron feeder to a vibrating grizzly feeder (to scalp off fines) ahead of the primary crusher. A single toggle jaw crusher will be sized for the purpose of primary crushing.

Leaching, using acidified raffinate and/or sulphuric acid, will take place in four mechanically agitated tanks operating in a series overflow cascade configuration under atmospheric conditions. A 25% W/w Sodium Metabisulphite solution will be also added to the leach tanks to facilitate the leaching of the Co3+ species by reducing the Co3+ to Co2+.

The slurry from the final leach tank will be washed, with cobalt effluent solution topped up with return dam solution, and then thickened in a series of five counter current decantation CCD thickeners. Alternate wash water will be sourced in order of preference from process water, raw water or raffinate.

The overflow from the first CCD thickener will be treated in a clarifier to reduce the amount of suspended solids in the pregnant leach solution (“PLS”). Overflow from the clarifier will gravitate to the PLS pond while the underflow from the final CCD thickener will be pumped to the tailings disposal tank. The clarifier underflow will be pumped back to the CCD circuit or the clarifier feed tank. Due to the need to further dilute the discharge from the final leach tank in the CCD thickeners before thickening to ensure optimum settling of solids, high rate thickeners with auto feed dilution will be incorporated into the design.

The PLS (aqueous phase) will be pumped to two extraction mixer settlers where it will be mixed with an organic solvent solution consisting of an extractant and diluent (organic phase). The solvent solution will extract the copper from the PLS producing a copper loaded organic stream (loaded organic) and a copper depleted aqueous stream (raffinate).

The loaded organic will be mixed with a solution from electrowinning (spent electrolyte) in two stripping mixer settlers where it will be stripped of the copper producing an advance electrolyte. This advance electrolyte will be filtered using dual media filters to remove entrained organic solution, to prevent ‘organic burn’ on the deposited copper. The advance electrolyte will then be heated using a heat exchanger prior to it being fed to electrowinning. The stripped solvent solution (stripped organic) will be returned to the extraction mixer settlers.

Advance electrolyte will be pumped to 16 polishing cells before being pumped to 66 commercial cells. Each cell will have 48 cathodes and 49 anodes. Copper will plate onto the cathodes by the process of electroplating. Blank stainless steel cathodes and lead anodes will be used in the cells. The spent electrolyte from the electrowinning banks will be pumped back to the strip section of solvent extraction. After the plating cycle, the cathodes will be removed from the electrowinning cells, washed in a hot water tank, the deposited copper stripped from the cathodes using a semi automatic stripping machine and the blank cathodes returned to the cells. The copper stripped from the cathodes will be the finished copper product.