Overview

Deposit type

• Sediment-hosted
• Breccia pipe / Stockwork
• Stratabound

Summary:

Zone 5 and the adjacent deposits are characterised as structurally controlled, sediment hosted strata-bound copper-silver deposits.

Zone 5 has a deposit strike length of 4.2km with mineralisation dipping at 56 degrees to the south-east over an average thickness of 10 m. Mineralisation is situated in the hanging wall sequence, 30m above the contact between the D'Kar Formation and Ngwako Pan Formation. Mineralisation is sub-parallel to lithology and typically cross-cuts host units from the lower D’Kar limestone unit in the south-west to the carbon rich siltstone unit and interbedded alternating siltstone and sandstone unit toward the north-east. The host rock assemblage is sandwiched between two competent sandstone units; the footwall Ngwako Pan quartzite sandstone and the hanging wall Marker sandstone. The down dip extension of mineralisation has been drilled to a maximum depth of 1,200m vertically below surface. The deposit remains open at depth (down dip) and partially along strike.

Mineral boundaries were interpreted to distinguish areas that comprised overburden, oxide plus sulphide minerals and sulphide-only assemblages. The near surface mineralised zone was identified as a transitional sulphide zone that contained both oxide and sulphide minerals. The boundary between this zone and the sulphide only undulates parallel to topography between 60 and 80m depth below the surface. This boundary was defined by acid soluble copper and total copper ratios, logged drill core and recorded specific gravity values. Common minerals found in this zone, in order of abundance, include malachite, bornite, chalcopyrite, native copper and minor chrysocolla. A small zone of deeper oxidation, with mineralisation consisting dominantly of native copper, is located in the centre portion of the deposit. This area shows strong brecciation and extends to depths of 400m below the surface.

Economic mineralisation consists of massive bornite and chalcocite with accompanying chalcopyrite and silver. Locally, secondary massive chalcocite has replaced bornite in the Central portion of the deposit at the forereef slope. These minerals are largely vein hosted and make up the greater than 1.0% Cu grade domain. The mineralisation is hosted within an extensive system of quartz and quartz carbonate veins, shears and cleavages. Parallel and sub-parallel shearing continues for hundreds of metres and are likely influenced by subtle changes in lithology and structure. Within the more competent units, shearing is replaced by brittle deformation, generally in the form of brecciation.

Localised parasitic folds, thrusts and shears have thickened the mineralisation and repeated the stratigraphy resulting in enhanced copper and silver grades over very wide intervals. Structural data in the NE portion of the deposit suggests a gently plunging fold toward the south-west. The fold is overprinted in the centre portion of the deposit by a vertically plunging facies change. These two areas have the highest grades and thickest intervals.

Please also refer to the exploration section that provides more detail on the regional geology.

Mining Methods

• Longhole open stoping

Summary:

The Zone 5 mine is a bulk mechanised mine, designed for a total production rate of 3.65Mtpa through three (3) mining corridors, with a single mining corridor production rate between 1.0Mtpa to 2.0Mtpa. The ore is transported to surface via a truck haulage system. The mine design is based on a Long Hole Open Stoping (LHOS) mining method. The first section of the mine incorporates pillars and no pastefill, and then as depth increases pastefill will be used to improve overall resource recovery.

Stope production has been designed around the use of 9m3 (21 tonne) loaders and 60 tonne haul trucks. In the mining areas, in specially designed truck loops, the loaders transfer the ore from the ore passes to the trucks. Given the current depth of the known mineral resource, trucking was deemed the most practical and the least capital-intensive option. From the loading points, the trucks travel up the decline(s) to the surface for dumping of the ore at the Run Of Mine (ROM) pads.

Given that the orebody has a strike length of more than 4km, it necessitated dividing it up into mining corridors due to the mining method selected, with twin decline systems dedicated to servicing each corridor. (the North Corridor starts as single decline.) The twin decline layout allows for more than 1,000m coverage of strike extent of the orebody, while offering multiple orezone attack points, highly productive layouts, and significant redundancy.

Surface access, through unconsolidated surface sands, to each of the 3 corridor decline systems is achieved through 3 boxcuts, which have dimensions 850 to 900m long, 400 to 450m wide and 52m deep, requiring excavation of 1.3million m³ of material per boxcut.

The decline profile has been designed at 6m x 6m to permit the passage of the largest fleet item, the haulage trucks, as well as for ventilation requirements, while maintaining required and statutory stand-off distances to the excavation walls and associated intermittent construction services (air, water, pumping, power, communications, and secondary ventilation) prior to being repositioned to the independent permanent infrastructure positions. An ergonomic style decline configuration with a minimum radius of 25m has been designed to provide optimal access to levels spaced 25 vertical metres apart, while also allowing trucks to operate at a safe productive speed when travelling up and down the decline. The downward gradient has been designed at 1:7 to maximize the capability of the haulage fleet whilst minimizing decline length per vertical metre.

The level intervals for the LHOS area have been designed at 25m vertical floor to floor based on a maximum accurate production drill hole lengths of approximately 30m. The flat level access is a horizontal drive that marks the beginning of a mine level, linking the decline access to the ore drive. Level accesses have been designed at 50m vertical intervals, however, this increases to 60m when passing the sill pillar locations. From the flat level access, access drives are inclined and declined to intersect the orebody on the 25m vertical level spacing where ore drives will be developed and utilized for stoping. The declines and associated orebody accesses have been positioned on the centroid of the corridors to maximise the corridor’s productivity.

Comminution

Crushers and Mills

Processing

• Jameson Cell Flotation
• Crush & Screen plant
• Flotation
• Dewatering

Summary:

The Boseto sulphide concentrator was upgraded from its original 3.0 million tonnes per annum nameplate capacity, to 3.65 million tonnes per annum to treat the Zone 5 ores. The ores respond well to conventional sulphide flotation, producing approximately 155,000 tonnes of high-grade copper concentrate at 40% Cu and 375g/t Ag. Since commissioning in mid 2021 the process plant has been successfully operated at design capacity and is achieving design performance parameters. The concentrate will be road hauled to port, for shipping and sale on the international market.

Metallurgical processing involves conventional bulk sulphide treatment and recovery including:
- 3-stage crushing and single-stage ball milling;
- Flash flotation, followed by conventional rougher flotation;
- Cleaner flotation with Jameson cells;
- Concentrate Regrind using Glencore HIG mill;
- The process is widely used in the base metals industry.

Production

Operational metrics

Personnel

Job Title	Name	Profile	Ref. Date
Exploration Manager	Oarabile Disang		Aug 9, 2024
Mining Contracts Manager	Brent Alting		Aug 9, 2024
Mining Manager	Logic Sebopeng		Aug 9, 2024
Technical Services Manager	Bava Reddy		Aug 9, 2024
Underground Mine Manager	Chris Harmse		Aug 9, 2024