PGM mineralisation at Mimosa is located in four erosionally isolated and fault-bounded blocks, namely, from north to south, the North Hill orebody, South Hill orebody, Mtshingwe Fault Block orebody and Far South Hill orebody areas. Each of these blocks is host to a pyroxenite layer known as the P1 pyroxenite layer which is overlain by a layer of gabbro. The platinum-bearing Main Sulphide Zone (MSZ) is located in the P1 pyroxenite some 10m below the ultramafi c/mafic contact. The MSZ is a continuous layer, 2m to 6m thick, and forms an elongated basin. The zone strikes in a north-northeasterly trend and dips at about 14° on the margins flattening towards the axis of the basin. The MSZ at Mimosa has a well-defined grade profi le where peak base metal and PGM values are offset vertically, with palladium dominant towards the base, platinum in the centre and nickel towards the top. At Mimosa the MSZ is visually identified using pyroxene and sulphide mineralisation followed by confirmatory channel sampling and underground XRF channel definition. Minor faults and dykes are present at Mimosa. Although no potholes have been identified, low-grade areas and areas of no mineralisation, or ‘washouts’, have been intersected. These are all accounted for in the Mineral Resource and Mineral Reserve estimate.

Mimosa is a shallow underground mine accessed by the two decline shafts, Wedza Decline and Blore Shaft. Mechanised bord and pillar mining method is used to extract ore over average stoping width of 2m. Historically, the bord widths have varied from 15m to 6m wide, depending on the ground control district. Minimum pillar sizes are dependent on depth to give a safety factor of greater than 1.6, with pillars being 10m by 3m for 18 Level and above, 10m x 4.5m from 20 to 28 Level in areas where 15m bords were mined. Current mining consists of 5.5m to 7m bord sizes with 8m by 4m for the whole mine. The bord sizes are 7m, 6.5m and 5.5m in GCD class C, D and E respectively. The strike pillars in panels are elongate on strike so that the longest dimension of the pillar intersects the dominant joint set (J1) at nearly 90 degrees. Most of the faults and dykes are part of the dominant J1 joint set.

The mining cycle involves mechanised support drilling and installation, MSZ channel definition and marking, mechanised face drilling, charging and blasting followed by mechanised lashing onto a conveyor network feeding to an underground bunker. From the bunker, ore is conveyed to a surface stockpile ahead of feeding into the processing plant. Optimum stoping widths and mining cut selection are regularly reviewed given variation in metal prices and the non-linear distribution of the different metals. Mining models are defined relative to the platinum peak position within the MSZ. The current planned mining horizon is a two-metre slice defined by the hanging wall at 0.45m above and the footwall at 1.55m below the Platinum peak position. This overbreaks to an actual mining width average of 2.1m. The reported mined grade is based on inverse distance block modelling of drillhole values using Surpac™.

Mine design and scheduling is computer aided using MineShed™ software. The mine plan is derived from a target milling throughput including a provision for a strategic surface stockpile. Losses due to mining modifying and geological factors are applied in production scheduling to produce a LoM production (tonnage and grade) profile. A tailcut has been effected on LoM I to exclude the last two years whose cash flows are negative. The LoM I tail cut tonnage is classed as LoM II A for opportunity extraction with LoM II. North Hill Mine is now at BFS stage and is classifi ed as LoM II. LoM I comprises extraction from the orebody’s Mineral Reserves at Wedza and Mtshingwe, which is the southern part of the South Hill orebody. Work is underway to assess various options to optimise extraction from different ore sources of the remaining Mineral Resources of Mimosa. The updated LoM indicates the mine plan, which dictated accelerated mining of the Mtshingwe Shaft area, in order to deliver a constant head grade and throughput to the mill.

Mimosa has a concentrator plant on site where initial processing is done. Concentrate is transported by road to Impala Platinum’s Mineral Processes in Rustenburg in terms of a life-of-mine offtake agreement with Impala Refining Services (IRS). Mimosa is evaluating various alternatives for the beneficiation of its material within Zimbabwe.