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Overview

Located near Randfontein, approximately 30km south-west of Johannesburg in the province of Gauteng, South Africa, the Cooke underground operations comprise three vertical shafts (Cooke 1 to 3 and the Ezulwini Plant) and the surface operation (with a dedicated processing facility), serviced by a developed network of mining and civil infrastructure with adequate electricity and water supplies. The operations have three individual new order mining rights – Cooke 1, 2 and 3 – covering 7,875ha. Mining at Cooke 4 ceased in the latter part of 2016.

At year end, the Cooke Operations consisted of three producing shaft systems as well as three metallurgical plants. Cooke 4 mining operations ceased after August 2016 as it proved uneconomical to mine even in a higher gold price environment.


Mine location
SA location
Coordinates
  • 28° 15'00"S
  • 24° 45'00"E

At year end, the Cooke Operations consisted of three producing shaft systems as well as three metallurgical plants. Cooke 4 mining operations ceased after August 2016 as it proved uneconomical to mine even in a higher gold price environment.

The underground operations are relatively shallow (~1,000m) with fewer seismicity or heat challenges than experienced at the neighbouring Kloof or Driefontein operations. The primary gold-bearing reef horizon mined at Cooke 1, 2 and 3 is Upper Elsburg Reefs.

Access to the Ezulwini uranium plant allows for production of uranium from underground ore mined at Cooke as a by-product. Sibanye has the option to recover uranium but this remains on hold until further notice.

The Cooke Plant was constructed in 1978 and has a nameplate capacity of 280,000tpm. In 2005, it was converted from a reef treatment plant to treat sand from the nearby high-grade Dump 20 tailings storage facility (TSF). High-grade ore from the Cooke 1, 2 and 3 shafts has been diverted for toll treatment at Harmony's Doornkop Plant.

Today, the Cooke surface operations process tailings from Dump 20 at a monthly rate of approximately 350,000t to produce approximately 32,000oz of gold annually. Mixed gold and uranium underground ore from Cooke 3 is treated at the dual-stream Ezulwini gold and uranium recovery plants. At current uranium prices, the recovery of uranium is not economically viable.

Key statistics

    2016 2015 2014
PRODUCTION        
Main development m 7,115 12,923 9,508
Area mined 000m² 175 205 176
Tonnes milled Mt 5.2 5.8 3.7
Yield g/t 1.09 1.08 1.17
Gold produced/sold kg 5,653 6,252 4,305
  000oz 182 201 138
COSTS AND MARGINS        
Operating costs R/t 575 514 461
– underground R/t 2,268 1,782 1,641
– surface R/t 90 83 82
Operating profit Rm 377 (4) 189
Operating margin % 11 0 10
Capital expenditure Rm 250 337 230
– sustaining Rm 49 93 52
– ore reserve development Rm 160 227 117
– projects Rm 41 18 61
Total cash cost R/kg 527,916 474,584 395,168
  US$/oz 1,119 1,158 1,136
All-in cost R/kg 595,959 541,843 445,645
  US$/oz 1,263 1,322 1,281
All-in cost margin % (1) (14) (6)

Hoisting and production capacities

Mining
unit
Operating
shaft
Operational hoisting
capacity (ktpm)
Planned production
ktpm)*
1 1 15 10
1 2 28 17
2 3 54 50
RSO TSF 400** 400

* Planned production is five-year hoisted average from 2017 onwards
** Reclamation capacity

Plant capacities

PlantDesign
capacity
(ktpm)
Current
operational
capacity (ktpm)
Average
recovery
factor (%)
Material
treated
Doornkop 80 80 95.5 UG
Ezulwini 200 115 94.6 UG
      80.0 SRD
Cooke 400 400 58.7 TSF

Performance in 2016

Total operation

Gold production of 5,653kg (181,700oz) was 10% lower than the previous year, mainly due to closure of Cooke 4 shaft in September 2016. The resultant lower volumes were partly offset by a 15% increase in underground yield to 4.19g/t.

Underground

Gold production decreased by 9% to 4,853kg (156,000oz) as a result of the termination of production at Cooke 4 Shaft. Excluding Cooke 4, underground gold production increased by 8% and yield increased by 15% from the previous year ended December 2015. This was partly due to closure of the lower yielding Cooke 4 and an improvement in the mine call factor (the ratio, expressed as a percentage, of specific product recovered at the mill, including residue, to specific product contained in an ore body – source: www.thisisgold.co.za).

Ore milled decreased by 21% to 1.16Mt due to a drop in square metres of which 15% was attributable to the closure of Cooke 4 Shaft. Main development decreased by 45% to 7,115m, in line with the planned decrease in metres.

Operating costs increased marginally to R2,626 million (US$179 million) mainly due to the decrease in volumes mined and processed with the cessation of mining activities at Cooke 4 as from the end of September 2016.

The operating profit of R274 million (US$19 million) compares favourably with a R58 million operating loss for the comparable period in 2015. The operating margin increased to 9% from -2% in 2015.

Capital expenditure decreased by 22% year on year to R246 million (US$17 million), mainly due to a decrease in capitalised ORD. Capital expenditure during the 2016 financial year was predominantly spent on capitalised ORD, the West Rand Tailings Retreatment Project, winder upgrades, the grout plant at Cooke 3 Shaft and community projects.

Surface

Gold production decreased by 10% to 800kg (25,700oz) for the year ended 30 December 2016 due to a 6% decrease in tonnes milled to 4.04Mt and a marginal decrease in yield to 0.20g/t in 2015.

Operating costs decreased marginally to R359 million (US$24 million). The surface operation contributed R103 million to operating profit and the operating margin increased from 13% to 23%.

Capital expenditure decreased by 88% year on year to R3 million (US$0.2 million), mainly due to Cooke 4 no longer capitalising assets as from the third quarter of the year.

Future focus

In 2017, the Cooke 4 Shaft will be rewatered with a view to improving operating costs at the Cooke operations. As the current surface operation source (Dump 20) will be depleted at the end of 2017, alternative economically viable sources are being evaluated.

Grade and volume remains a key focus area for the operation. A critical cost review will be undertaken in the coming year to ensure that the operation remains profitable.

Plugs will have to be designed and built between the Cooke 3 and 4 shafts to allow for the rewatering of 4 Shaft.