Mimosa

 

Mimosa
 

Mineral Resources and Ore Reserves

Mimosa is located 150km east of Bulawayo on the Wedza Complex of the Great Dyke in Zimbabwe. PGM mineralisation is located in four erosionally isolated and fault-bounded blocks, consisting from north to south of the North Hill, South Hill, Mtshingwe and Far South Hill areas. Mimosa holds contiguous mining rights over the above-mentioned areas totalling 6 591ha. The operation is a 50:50 joint venture between Implats and Aquarius.

The platinum bearing Main Sulphide Zone (MSZ) is located in the P1 pyroxenite some 10m below the ultramafic/mafic contact. The MSZ is a continuous layer, 2m to 3m thick, and forms an elongated basin. The zone strikes in a north-north-easterly trend and dips at about 10° on the margins flattening towards the axis of the basin. Mimosa has a well-defined grade profile 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. As at Zimplats, the MSZ is difficult to identify visually with no clear marker horizons.

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 Ore Reserve statement.

Mimosa is a shallow underground mine accessed by the Blore Decline Shaft system. The bord and pillar mining method is employed and stoping widths average around 2m. Mining bords advance along strike. The mining cycle involves mechanised support drilling and installation, mechanised face drilling, charging and blasting and mechanised lashing onto a conveyor network to an underground bunker. From the bunker ore is conveyed out to a surface stockpile.

 

Mining models are based on the platinum peak datum. Mining currently extracts a slice which extends from 0.45m above the platinum peak datum to 1.55m below the datum. The reported mined grade is based on an arithmetic mean of borehole values covering this slice. Work is ongoing to conduct this estimation using block modelling. Mine design and scheduling is done utilising SurpacTM. The mine plan is derived from a target milling throughput. Strategic stockpile levels are factored into the volumes to be hoisted. Losses due to mining and geology are applied to the planned tonnages and then consolidated into the LoM profile. The assured LoM of Mimosa is limited to the Wedza block. Studies continue on the South and North Hill blocks as potential for future mining.

 

Mimosa Mineral Resources and Ore Reserves (100%)  
as at 30 June 2012

 Mineral Resources         as at 30 June 2012         as at 30 June 2011  
    Tonnes   Width   4E  
grade  
6E  
grade  
Ni   Cu   4E   6E   Pt   Tonnes   4E  
grade  
6E  
grade  
4E   Pt  
 Orebody   Category   Mt   cm   g/t   g/t   %   %   Moz   Moz   Moz   Mt   g/t   g/t   Moz   Moz  
 South Hill  
 MSZ
  
Measured   40.4   200   3.96   4.22   0.14   0.11   5.1   5.5   2.5   42.9   3.96   4.22   5.5   2.6  
Indicated   27.6   200   3.62   3.85   0.14   0.12   3.2   3.4   1.6   27.6   3.62   3.85   3.2   1.6  
Inferred   6.9   200   3.72   3.97   0.14   0.12   0.8   0.9   0.4   6.9   3.72   3.97   0.8   0.4  
Inferred  
(oxides) 
4.4   200   3.58   3.84   0.14   0.12   0.5   0.5   0.3   4.4   3.58   3.84   0.5   0.3  
  Total   79.4     3.80   4.05   0.14   0.11   9.7   10.3   4.7   81.9   3.80   4.05   10.0   4.9  
 North Hill
 MSZ  
Measured   18.0   200   3.49   3.70   0.14   0.10   2.0   2.1   1.0   17.5   3.49   3.70   2.0   1.0  
Indicated   16.0   200   3.56   3.77   0.15   0.11   1.8   1.9   0.9   16.2   3.56   3.77   1.9   0.9  
Inferred   1.9   200   3.53   3.73   0.14   0.10   0.2   0.2   0.1   2.1   3.53   3.73   0.2   0.1  
Inferred  
(oxides) 
7.9   200   3.39   3.62   0.15   0.11   0.9   0.9   0.5   9.5   3.39   3.62   1.0   0.6  
  Total   43.9     3.50   3.71   0.15   0.11   4.9   5.2   2.5   45.4   3.49   3.71   5.1   2.6  
 Far South
 Hill MSZ  
Inferred   11.3   200   3.78   4.03   0.14   0.11   1.4   1.5   0.7   11.3   3.78   4.03   1.4   0.7  
Overall total   134.7     3.70   3.94   0.14   0.11   16.0   17.0   7.9   138.6   3.70   3.94   16.5   8.1  
                               
 Ore Reserves         as at 30 June 2012         as at 30 June 2011  
    Tonnes   Width   4E  
grade  
6E  
grade  
Ni   Cu   4E   6E   Pt   Tonnes   4E  
grade  
6E  
grade  
4E   Pt  
 Orebody   Category   Mt   cm   g/t   g/t   %   %   Moz   Moz   Moz   Mt   g/t   g/t   Moz   Moz  
 South Hill
 MSZ
  
Proved   17.2   200   3.59   3.82   0.14   0.12   2.0   2.1   1.0   18.9   3.59   3.82   2.2   1.1  
Probable   12.2   200   3.39   3.61   0.15   0.12   1.3   1.4   0.7   12.1   3.39   3.61   1.3   0.7  
  Total   29.4     3.51   3.73   0.14   0.12   3.3   3.5   1.7   31.1   3.51   3.74   3.5   1.7  

 

Notes

  • The statement above reflects the total Mineral Resource and Ore Reserve estimates for Mimosa as at 30 June 2012. Corresponding estimated Mineral Resources and Reserves attributable to Implats are summarised elsewhere in the report
  • Mineral Resources are quoted inclusive of Ore Reserves
  • Mineral Resources are quoted before accounting for anticipated pillar losses. Predicted geological losses have been subtracted from the Mineral Resource estimates
  • Mineral Resource and Reserve estimates are based on a 2m mining width
  • Additional surface drilling during the past year targeted the Oxides at both North Hill and South Hill; this resulted in the refinement of the Oxide boundaries
  • The 2012 estimate essentially reflects depletion since 2011
  • Rounding-off of numbers may result in minor computational discrepancies.

 

 

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