Marula

 

Marula
 

Mineral Resources and Mineral Reserves

The Marula mining operation is located on the eastern limb of the Bushveld Complex, some 35km north-west of Burgersfort. Marula holds two contiguous mining rights and a prospecting right covering 5 494ha across the farms Winnaarshoek and Clapham, and portions of the farms Driekop, Forest Hill and Hackney. Marula also has a royalty agreement with Modikwa Platinum Mine which allows limited mining on an area adjacent to the Driekop Shaft. These Mineral Resources and Mineral Reserves have not been reflected in the current statement as ownership still rests with Modikwa. Implats has an effective 73% interest in Marula with each of the three empowerment groupings (Mmakau Mining, the Marula Community Trust and Tubatse Platinum) holding a 9% interest.

Both the Merensky and UG2 Reefs are present but only the UG2 is currently exploited. The geological succession is broadly similar to that of the western limb. The UG2 Reef is defined as a main chromitite layer, with most of the mineralisation confined to this unit, followed by a poorly mineralised pegmatoidal footwall. The Merensky Reef is the upper portion of a pyroxenite layer, with a chromitite stringer close to the hangingwall contact. Mineralisation peaks over the chromitite stringer and decreases into the hangingwall and footwall.

Both mineralised horizons sub-outcrop on the Marula mining rights area and dip in a west-south-west direction at 12° to 14°. The vertical separation between the Merensky and UG2 Reefs averages 400m. The reefs are relatively undisturbed by faults and dykes, with potholes representing the majority of the geological losses encountered underground. One major dyke traverses the mining area. A dunite pipe and potholes disrupt the reef horizons. These geological features are accounted for in the Mineral Resource and Mineral Reserve statements as geological losses.

Marula Mine has two decline shaft systems. Driekop Shaft is exploiting the UG2 Reef by means of a hybrid mining method, whilst at Clapham Shaft, both a hybrid and conventional mining method are currently being used to exploit the UG2 Reef.

For the two hybrid sections, all main development is done on reef, and the stoping is carried out through conventional single-sided breast mining from a centre gully. Panel face lengths are approximately 16m to 20m, with panels being separated by 6x4m grid pillars with 2m ventilation holings. The stoping width averages 1.4m.

For the conventional operation, the footwall drives are developed on strike approximately 25m below the reef horizon with cross-cut breakaways about 220m apart. This development is done with drill rigs and dump trucks. Panel lengths are approximately 24m. Stope face drilling takes place with hand-held pneumatic rock drills with air legs.

Mine design and scheduling of the operational shafts is carried out utilising CadsMine™ software. Geological models and ore blocks are updated and validated using G-Blocks and boundaries in the MRM information system. Grade block models are developed utilising Isatis™. The mine design and scheduling for the first five years is done in much more detail – monthly per crew. Thereafter, yearly rates are applied.

The LoM I encompasses the Clapham hybrid, Clapham conventional up to 4 Level, Driekop hybrid and Driekop Extension. This will take the mine to a sustainable production level of 1.95 Mt per annum up to 2017. Maintaining the profile after 2017 is the subject of ongoing studies to optimise the LoM II and LoM III in the 30-year LoM profile. The comparison between the Mineral Resource statement and the 30-year LoM profile clearly illustrates its potential to expand operations in future if economically viable. Note that the indicative LoM profile is based and a range of assumptions and could change in future.

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

 Mineral Resources        as at 30 June 2012        as at 30 June 2011  
 Orebody   Category   Tonnes  
Mt  
Width  
cm  
4E  
grade  
g/t  
6E  
grade  
g/t  
4E  
Moz  
6E  
Moz  
Pt  
Moz  
Tonnes  
Mt  
4E  
grade  
g/t  
6E  
grade  
g/t  
4E  
Moz  
Pt  
Moz  
 Merensky   Measured   34.3   100   4.24   4.55   4.7   5.0   2.7   34.3   4.24   4.55   4.7   2.7  
  Indicated   7.7   100   4.26   4.54   1.1   1.1   0.6   7.7   4.26   4.54   1.1   0.6  
  Inferred   9.9   100   4.16   4.46   1.3   1.4   0.8   9.9   4.16   4.46   1.3   0.8  
 UG2   Measured   32.2   58   8.71   10.07   9.0   10.4   3.9   31.7   8.57   10.07   8.7   4.0  
  Indicated   12.5   61   8.85   10.32   3.6   4.1   1.6   12.0   8.66   10.22   3.4   1.5  
  Inferred   6.2   59   8.86   10.33   1.8   2.1   0.8   6.6   8.70   10.29   1.8   0.8  
  Total   102.8     6.47   7.32   21.4   24.2   10.3   102.2   6.39   7.29   21.0   10.4  
 Mineral Reserves        as at 30 June 2012        as at 30 June 2011  
 Orebody   Category   Tonnes  
Mt  
Width  
cm  
4E  
grade  
g/t  
6E  
grade  
g/t  
4E  
Moz  
6E  
Moz  
Pt  
Moz  
Tonnes  
Mt  
4E  
grade  
g/t  
6E  
grade  
g/t  
4E  
Moz  
Pt  
Moz  
 UG2   Proved   2.4   165   3.93   4.55   0.3   0.4   0.1   2.6   3.97   4.68   0.3   0.2  
  Probable   23.8   166   4.05   4.70   3.1   3.6   1.4   25.5   3.99   4.70   3.3   1.5  
  Total   26.2     4.04   4.69   3.4   4.0   1.5   28.1   3.99   4.70   3.6   1.6  

 

 

Notes

  • The statement on here reflects total estimates for Marula as at 30 June 2012, corresponding estimated attributable Mineral Resources and Reserves are summarised elsewhere in the report
  • Mineral Resources are quoted inclusive of Mineral Reserves
  • Mineral Reserves quoted reflect the width and grade delivered to the mill rather than an in situ channel grade quoted in respect of the Mineral Resources
  • The modifying factors used in the UG2 Mineral Reserve calculation are based on the mine plan which envisages hybrid and conventional breast mining operations
  • Estimated geological losses have been accounted for in the Mineral Resource calculation.
  • The UG2 Mineral Resource accounts for the main chromitite layer channel width only, without consideration of dilution
  • Grade estimates were obtained by means of ordinary kriging of borehole intersections
  • No additional work was done on the Merensky Mineral Resource estimation during the year and the same statement is reported as in 2011
  • Changes in the UG2 Mineral Resource estimates since last year reflect an updated estimation using additional data and some adjustment of extraction rates
  • The Mineral Resource and Mineral Reserve are reflected in both 4E and 6E formats
  • Rounding of numbers may result in minor computational discrepancies.


 

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