The Kombat mineralised zones are carbonate-hosted base metal sulphide deposits associated with hypogene filled karst cavities and only occur along parallel “roll structures”, which are thrust-related folds. One “roll” parallel to the main Kombat Mine “roll” is present at surface at Kombat Station approximately 1,500 m to the north. The mineralised karst is thought to be caused by the upward migration of corrosive, evaporitederived brines through the Huttenberg carbonates. These brines were expelled from the basin during compression, migrated up the thrusts into folds and encountered oxidized meteoric groundwater and formed corrosive suphuric and carbonic acids. These acids were blocked by the impermeable and reducing Mulden shales resulting in the precipitation of base metal sulphides.

The orebodies are epigenetic, hydrothermal, and metasomatic replacement and fracture-fill Cu-Pb-(Ag) type deposits. Common to all types of mineralisation is the small quantity of associated hydrothermal gangue minerals such as calcite, quartz, dolomite, and seldom barite. The degree of oxidation of massive sulphides is independent of the depth, it is controlled by the proximity of the ores to the water-bearing faults and steeply foliated sandstone aquifers.

Massive and Semi-massive Sulphides are elongated, foliated zones of mineralised dolostone related to centres of tectonic and sedimentary brecciation in dolostone stratigraphy. The replacement ore is best developed in breccia matrices, lenses of feldspathic sandstone, in pervasively calcitised dolostone and particularly in oölitic, pelletal/detrital units closest to the slate contact.

At least four breccia types can be distinguished. These are firstly the syn-depositional sedimentary breccia with angular dolostone clasts in a micritic and often calcitic matrix and secondly the stylo-breccia with an anastomising or quadrangular meshwork of net-vein fractures. The fault breccia (associated with post-ore fractures) and the solution collapse breccia (associated with karsting and localised by a north-east trending fault) have little volumetric extent and no control on hypogene mineralisation (Innes and Chaplin, 1986). A foliation is frequently superimposed where breccia grades into transposition breccia in which clasts are attenuaded and boudinaged. High grade mineralisation extends away from the centres of brecciation along zone of recrystalised dolostone. All gradations of mineralisation from finely disseminated sulphides to completely replaced rock exist in the sandstone and in the dolostone.

A reticulate or anastomosing mesh of mineralised calcitic micro-fractures is developed adjacent to shears, faults and broad zones of pervasive calcitization below massive sulphides. It is therefore regarded as the “root zones” of the massive ore (Dean, 1995). With increasing deformation it grades into sutured stylolites. The stylo-cumulates contain magnetite, bornite, galena and chalcopyrite. In oxidised zones chalcocite, malachite, copper and hematite are found. It is common for mineralisation of this type to merge into alteration breccias and massive replacement Cu-Pb ores (Innes and Chaplin, 1986).

Galena-rich Alteration Breccias are confined to Kombat East orebodies where steep breccia bodies of pipe-like configuration exist. An unaltered core of close-packed angular dolostone blocks is surrounded by a bleached, calcitised fringe induced by hydraulic fracturing which permitted increased fluid flow along the fracture system. The mineral assemblage comprises galena, pyrite and subordinate chalcopyrite.

It is an alteration facies of the feldspathic sandstone affected by penetrative deformation and therefore formed early in the mineralizing process. Fine-grained, euhedral pyrite is disseminated in a generally strongly foliated sericite-quartz matrix. Ore minerals are seldom present.

Iron-manganese Oxide/silicate Association
This compositionally and texturally layered Fe- and Mn-assemblage is always associated with feldspathic sandstone and discrete steeply orientated zones of tectonic deformation. It forms an integral part of the orebodies of Asis West, Kombat Central and Kombat East. Larger bodies, with an estimated undeformed size of 50 m in length by 10 m thick comprise hematite and magnetite in juxtaposition to layered Mn-oxides and -silicates within a zone of transposition. The main banded ore minerals are magnetite, hausmannite, hematite, barite, calcite, tephroite, alleghanyite, pyrochroite, and small amounts of pinkish jasperoidel rock. Mn-ores are fine grained and polymineralic aggregates with a well-defined internal mineral banding (band width: 1 to 6 mm) of magnetite alternate with the assemblage leucophoenicite-tephroite-Cu and kutnahorite-barite-barysilite. The layered Fe-Mn bodies are confined to the Kombat Mine and predate the sulphide formation.

Epithermal Association
This association commonly comprises transgressive vuggy veins containing euhedral calcite, quartz, and chalcopyrite. It postdates the main period of mineralisation. In addition, a number of narrow veins containing galena, sparry rhodochrosite, helvite, and barite cross-cut the lenses of Fe-Mn oxides/silicates and adjacent bodies of massive galena-chalcopyrite (Innes and Chaplin, 1986).

Sulphide and carbonate minerals occur in zones around and running parallel to the major northeast striking cross-cutting faults. The malachite-azurite zone averages 50 m in width and is closest to the faults. The covellite-chalcocite zone is approximately 50 m wide and further away from the fault and the covellite-chalcocite zone is up to 100 m wide and surrounded by the chalcopyrite zone. The zonation marks the alteration of the basic chalcopyrite mineralisation by oxidizing groundwater. Broad zones of calcitisation flank sulphide lenses; at depth, these can form 200-300 m widths of sugary limestone. Calcitisation is the dominant alteration associated with mineralisation. Steeply dipping lenses of compositionally and texturally layered Fe-Mn oxide-silicate mineralisation are generally found near feldspathic sandstone lenses and are commonly associated with the peripheries of the Cu-Pb mineralised zones. These Fe-Mn bodies are layered, lenticular and typically 100 m long by 50 m wide and may reach sizes up to 300 m long by 100 m wide.

The 2021 Kombat update focuses on the Kombat Open Pits. No underground mining of the Kombat orebodies has been included in the update.

The mining method that will be used at the Kombat Project will be conventional open pit mining with the addition of waste backfilling of the existing ore capping hole where one of the open pits are planned. Mining activities will be conducted by a mining contractor who will be responsible for drilling, blasting loading and hauling. Drilling will be conducted using drill rigs, loading will be done using hydraulic excavators and hauling will be via haul trucks. Backfilling of the voids will be conducted by the contractor using dozers.

The Kombat Open Pits production schedule aims to deliver 30 kt of RoM per month from the Kombat East and Kombat Central open pits to the processing plant at an average grade of 1% Cu. A ramp-up period of four months, commencing at 10 kt RoM and ramping up in 5 kt RoM increments per month, has been incorporated into the production schedule to reach steady state production of 30 ktpm RoM in month five.

The processing plant will follow the same ramp-up increments as the production schedule. Initially, the process plant will treat 10 kt of RoM in month one of the processing schedule (month four of the mining schedule) and processing will ramp up to steady state production in 5 ktpm increments per month, for four months.

The combined overall stripping ratio over the LoM, is 6.83:1 (tonnes waste : tonnes ore). A LoM of approximately 45 months with a plant feed of 55 months is envisaged, equating to an overall LoM of approximately five years.

A total of 1.54 Mt diluted ore tonnes at a mined grade of 1.14% Cu will be delivered to the plant over the LoM. This equates to 17,559 Cu tonnes delivered to the plant.

The existing ore capping hole within the planned East 1 open pit requires backfilling prior to mining operations commencing within the pit. The stripping ratio is initially high to produce sufficient waste material for the construction of windrows and backfilling of the ore capping hole.

The mining schedule has been conducted to firstly prioritize waste to the planned windrows, followed by filling of the ore capping hole. The waste material required for the construction of windrows will be produced in the first four months of the mining schedule. Filling of the ore capping hole commences in month four and is completed in month 15, requiring 12 months to be completely filled. Remining of the backfilled waste material takes place as the East 1 Pit is mined and the remined waste material from the ore capping hole and waste material from the East 1 Pit is moved to the WRD (waste rock dump).

PRIMARY CRUSHING
RoM material will be delivered over a static grizzly screen by tipper trucks. RoM material will also be stockpiled and fed into the plant by front end loaders as required. The screen underflow will discharge into a bin and then onto a vibrating grizzly screen. The screen undersize (-100 mm material) will gravitate onto a conveyor while the oversize (+100 mm material) will discharge into the primary jaw crusher. The jaw crusher product will combine with the grizzly underflow and then be conveyed into a 100-tonne silo.

SECONDARY CRUSHING
The silo will ensure a consistent feed to the downstream screening and secondary crushing circuit. The silo product will be delivered onto a vibrating grizzly screen. The grizzly undersize (-50 mm) will discharge onto the wet doubled deck screen. The grizzly oversize material (+50 mm) will discharge onto conveyors before the dry double deck screen.

The wet screen oversize (+15-50 mm) will be conveyed and combine with the grizzly oversize. The wet screen middlings (+2-15 mm) will be conveyed to the mill silos. The wet screen underflow (-2 mm) will be pumped to the fines thickener. The dry double deck screen oversize (+35 mm) will be crushed in a cone crusher with its product conveyed back to the dry screen. The dry deck middlings (+15-35 mm) will be conveyed into the short head cone crusher. The short head cone crusher product will combine with the dry deck underflow (-15 mm) and the wet screen middlings (+2-15 mm) onto the mill silos together with wet screen middlings.

MILLING
The three mill feed silos feed three rod mills. The silos will ensure that the total rod mill circuit operates at approximately 48 tph (16 to 17 tph per rod mill) to ensure that a throughput of 1,071 tpd is achieved. Silos 1 and 2 will discharge onto a conveyor and split between rod mill 2 and 3. Silo 3 will discharge onto a conveyor and feed into rod mill 1. The rod mills will discharge into a common sump with the sump contents pumped to one of the two primary cyclones.

The wet screen underflow (in the secondary crushing circuit) will be pumped into the 30 ft fines thickener. The thickener underflow will be pumped into the rod mill discharge sump. The cyclone overflow will gravitate into the regrind mill sump while the underflow will gravitate and split into the two ball mills. The mill discharge will be fluidised with water and gravitate into the rod mill discharge sump.

The regrind mill sump contents will be pumped into one of two secondary cyclones. The secondary cyclone underflow will gravitate into the regrind mill feed tank and then be pumped into the regrind mill. The regrind mill product will be fluidised and gravitate into the regrind mill sump. The cyclone overflow will gravitate to the float circuit feed conditioning tank.

Cyclone classification will be controlled by adjusting the cyclone feed flow rate with the discharge sump pump variable speed drive (“VSD”), while the feed density will be controlled by manipulating the sump dilution water. A constant density and constant flow rate will ensure that the cyclone feed pressure is steady which will improve cyclone cut efficiency and reduce recirculating load and overgrinding of material. The milling circuit will be controlled to ensure a final grind of 80% passing 90 µm and a final cyclone overflow with at least 30% solids. The final slurry density will be adjusted in the float feed conditioning tank.

The existing Kombat plant has a capacity of 30 ktpm and will be refurbished to treat open pit RoM material. The plant consists of three-stage crushing and screening, rod and ball milling, flotation, concentrate thickening and filtering circuits which used to be capable of producing separate copper and lead concentrates. Only the copper concentrate section will be refurbished and no lead concentrate will be produced.

The plant will produce a copper concentrate of 22% Cu which will be trucked and exported via the port of Walvis Bay. Flotation tailings will be deposited on a newly constructed TSF adjacent to the processing plant. The plant consists of industry standard processing equipment and well-understood processing recovery methods and is deemed to be appropriate to treat the targeted open pit material.

FLOTATION
The flotation circuit will receive new cells as part of the refurbishment project. The historic flotation process flow will be modified and will c ........