Open pit mining at Ebenhaezer, the satellite pipe at Koffiefontein

  • Bookmark

Fissures

Overview

The fissure mine portfolio comprises three mines: Helam, Sedibeng and Star. The Sedibeng operation is an amalgamation of two mines: Messina and Dancarl. The mines are operating at depths of between 600 and 750 metres. Plans to increase production from just over 87,000 carats in FY 2011 to 140,000 carats per annum by FY 2015 are currently being implemented. Sedibeng is located 80 km North West of Kimberley in the Northern Cape Province, whilst Star is located some 40 km South of Welkom in the Free State Province. Helam is located 70 km West of Rustenburg in the North West Province.

Key Facts
Location South Africa
Strike length of fissure at surface Helam: 6km
Sedibeng: 2.4km
Star: 4.5km
Mine start date Helam: 1933
Sedibeng: 1952
Star: 1952
Acquisition by Petra Diamonds May 2005 (further to merger with Crown Diamonds NL)
Ownership Helam: 74% Petra Diamonds, 26% Sedibeng Mining (Pty) Ltd
Sedibeng: 74.5% Petra Diamonds, 17.85% Sedibeng Mining (Pty) Ltd, 7.65% Bokone Properties (Pty) Ltd
Star: 74% Petra Diamonds, 26% Sedibeng Mining (Pty) Ltd
Operator Petra Diamonds
Total Resources
(Resources inclusive of Reserves)
5.0 Mcts
Current depth of Resources 970m
Mining Method Helam & Sedibeng: Full shrinkage overhand stoping
Star: Open stope underhand
Depth of current mining Helam: 750m
Sedibeng: 750m
Star: 620m
Mine Plan Helam: 20 years
Sedibeng: 11 years
Star: 15 years
Potential Mine Life +15 years
History

Helam, Sedibeng and Star are all well-established underground fissure mines which have been in operation for more than 50 years. Each mine exploits narrow diamondiferous kimberlite fissures using labour intensive mining methods.

Reserves & Resources
CategoryGrossNet attributable
Tonnes (millions)Grade (cpht)Contained Diamonds (Mcts)Tonnes (millions)Grade (cpht)Contained Diamonds (Mcts)
Reserves
Proved 1.444 47.35 0.684 1.071 47.29 0.507
Probable 2.044 60.78 1.242 1.514 60.74 0.920
Sub-total 3.488 55.22 1.926 2.586 55.17 1.426
Resources
Measured 0.547 149.61 0.82 0.406 149.39 0.606
Indicated 0.827 182.60 1.509 0.612 182.46 1.117
Inferred 1.654 163.12 2.698 1.226 163.00 1.998
Total Resources inclusive of Reserves 3.028 166.00 5.026 2.244 165.85 3.722
  • Resource bottom cut-off: 1mm
  • Reserve bottom cut-off: 1mm
  • Measured Resources are classified as 1 level below current workings, or where a block is bounded above and below by current workings
  • Indicated Resources are classified as 2 levels below measured Resources
  • Inferred Resources are classified as 3 levels below indicated Resources
  • Measured and indicated Resources have been converted to Reserves by applying historically derived external dilution and in-stope loss factors to resource tonnages and grades
  • Increase in Inferred Resource based on the diamond drilling programme at Sedibeng
FY 2011 Results
All figures stated gross Unit FY 2011 FY 2010 Variance
Sales
Revenue US$M 21.8 13.5 +62%
Diamonds sold Carats 89,491 72,629 +23%
Average price per carat US$ 244 185 +32%
ROM Production
Tonnes treated Tonnes 183,506 168,840 +9%
Grade Cpht 45.7 42.0 +9%
Diamonds recovered Carats 83,876 70,950 +18%
Tailings Production
Tonnes treated Tonnes 52,389 30,640 +71%
Grade Cpht 6.9 10.7 -36%
Diamonds recovered Carats 3,612 3,282 +10%
Total Production
Tonnes treated Tonnes 235,895 199,480 +18%
Diamonds recovered Carats 87,488 74,232 +18%
Costs
On-mine cost per tonne ZAR 684 669 +2%
Total Capex US$M 5.2 2.5 n/a

Helam and Sedibeng put in a strong performance in FY 2011, with revenue for the Fissures unit as a whole up 62% to US$21.8 million and overall production up 18% to 87,488 carats. The average value per carat achieved also increased 32% to US$244.

For FY 2012, Petra expects a similar level of combined production across the fissure portfolio to FY 2011.

At Star, where operations are challenging, a disappointing performance was recorded for the year, as reflected in the impairment charge incurred.

Unit costs remain flat despite cost pressures specifically relating to electricity and labour. The majority of the US$5.2 million Capex was spent on continuing underground development across the fissure mines including a head gear installation at Sedibeng’s Dancarl shaft.

A further US$11.0 million Capex spend was incurred in respect of the Helam projects manufacturing facility for equipment under construction for other mines and projects within the Group.

Mine Plan

Plans to increase production from just over 87,000 carats in FY 2011 to ca 140,000 carats per annum by FY 2015 are being implemented.

Top of page ^