The Mumbwa licence area lies within the extreme southern portion of the Neoproterozoic Lufilian Arc. The Lufilian Arc is a large arcuate fold and thrust belt covering northwestern Zambia, the southern Democratic Republic of Congo and eastern Angola.

The geology of the Mumbwa area is described by Cikin and Drysdall (1971). The region is dominated by metasedimentary rocks of the upper units of the Neoproterozoic Katanga Sequence. These rocks are intruded by the large syn- to post-tectonic 566-533 Ma Hook Granitoid Suite and by younger post-tectonic syenites, diorites, porphyry granites, granites, diorites and gabbros. The east-northeast trending MSZ runs along the southern margin of the Hook Granitoid Suite.

The Mumbwa district represents an IOCG province that is related to voluminous anorogenic (Atype), alkali and granitoid magmatism and tectonic activity that took place from 570-500 Ma along a Pan-African transform plate boundary that separated the Congo and Kalahari Cratons (Pelly, 2001). IOCG systems associated with the Hook Granitoid Suite and related intrusions in the Mumbwa district display many of the typical characteristics of IOCG systems.

IOCG deposits comprise a broad and ill-defined clan of mineralisation styles, which are grouped together chiefly because they contain hydrothermal magnetite and/or specular hematite as major accompaniments to chalcopyrite ± bornite. Apart from copper and byproduct gold appreciable amounts of Co, U, REE, Mo, Zn, Ag, Nb and P may also be present.

Deposits vary between magnetite-apatite deposits with actinolite or pyroxene (Kiruna type) and hematite magnetite deposits with varying amounts of copper sulphides, Au, Ag, uranium minerals and REE (Olympic Dam type). Typically, these systems are characterized by >20% iron oxides. Iron-rich zones, breccias and alteration halos associated with IOCG systems can reach hundreds of metres in width and many kilometres in length.

Deposits are localized along high- to low-angle faults which are generally splays off major, crustal-scale faults. Structural control can vary from the intersection of highly permeable units with fault zones, dilational jogs, duplexes, splays on faults and shears, folding or complex intercalation of high and low permeability units all influencing fluid flow regimes and ultimately the position of alteration zones, breccias and/or ore deposition.

Sub-level caving was selected as the appropriate mining method at the completion of the Pre Feasibility study. This was due to the deposit being too deep (overlain by waste) for open pit mining and having insufficient rock mass strength to be efficiently mined by stoping methods.

Production tonnages are modelled to an economic shut off grade of 0.9% copper, not exceeding the maximum draw percentages listed below:
- first level – 40% of tonnes;
- second level – 60% of tonnes;
- third level – 90% of tonnes;
- fourth level – up to 120% of tonnes;
- fifth and consecutive levels – up to 150% of tonnes.

The process comprises a comminution circuit followed by froth flotation to yield separate flotation concentrate and tails streams. The concentrate is fed to a pressure oxidation (“POX”) autoclave to simultaneously leach the copper, and to generate sulphuric acid and heat. The autoclave discharge slurry is combined with the flotation tails in an atmospheric acid leaching circuit to extract the copper in the oxide and secondary sulphide copper minerals. The final leach liquor is separated from the barren leach solids in a counter-current decantation circuit to yield a pregnant leach solution (“PLS”) which is then fed to a solvent extraction (SX) circuit. The loaded strip liquor (rich electrolyte) is subsequently pumped to an electrowinning (“EW”) circuit to generate copper cathode. A facility is provided to enable supplementary sources of sulphur (either as chalcopyrite concentrate and/or elemental sulphur) to be added to the POX leaching circuit, thereby providing flexibility during low ........