Name and Location
South Deep gold mine expansion, Gauteng, South Africa.

Client
Gold Fields.

Project Description
South Deep is a fully mechanised underground mine, extracting a wide multiple band reef at depths of between 2 000 m and 3 000 m below surface. The extraction of such deep-level, wide reefs have not been totally mechanised elsewhere in the world. The production methods used at the mine are, therefore, unique and differ markedly from the labour-intensive mining method traditionally applied in underground mines in South Africa.

The project comprises a main shaft and a ventilation shaft – collectively referred to as the Twin Shaft complex, which will have a combined hoisting capacity of 370 000 t/m of ore.

The main shaft was completed in 2004 and comprises a single drop to a depth of 2 995 m.

The ventilation shaft has been deepened from 2 760 m to about 2 950 m and is fully equipped with ore-storage silos and conveyor belts at shaft bottom, a new rock winder and new headgear.

The mine’s headgear at the vent shaft was completed in 2011 using one of the largest fabricated steel headgear frames in the world.

The South Deep metallurgical plant, which was commissioned in November 2012, has also been expanded and has increased processing capacity from 220 000 t/m to 330 000 t/m.

From 2010 to 2012, the mine completed the construction of the centralised tailings storage facility, developed and installed infrastructure around the shaft systems and also changed to full plant tailings backfill for increased production levels. The backfill plant was commissioned in early 2012.

The South Shaft complex will add an additional 120 000 t/m of hoisting capacity to the mine, bringing the total combined hoisting capacity to 450 000 t/m.

The South Deep operation had a mineral resource of 70-million ounces as at December 31, 2013, and a mineral reserve of 35.1-million ascertained ounces, which will give the operation a life-of-mine (LoM) until about 2087.

Value
An estimated $4-billion has been invested to date.

Duration
A timeline for the roll-out to steady-state production is still being developed.

Latest Developments
Gold Fields has reported in its results for the quarter ended June 30, 2015, that it will maintain its full-year production guidance of about 2.2-million ounces, even though production at South Deep is now expected to decrease from 7 100 kg to 6 500 kg, owing mainly to a deliberate focus on fixing the base for a sustainable long-term future. The company, however, maintains its goal of achieving cash breakeven by the end of 2016.

Production for the June quarter was 7% higher at about 1 203 kg, despite numerous safety-related stoppages. Increased production in the second half of 2015 is expected to be driven by a contribution from large-volume long-hole stoping and the introduction of a new fleet, which has been factored into Gold Fields’ capital forecast of about R1-billion for the year.

The new fleet will increase the complement of category I equipment – rigs, loaders and trucks – by one-third. These new additions will significantly increase available equipment.

The fleet will comprise an additional 27 pieces of category I equipment, in addition to the 75 pieces in service, of which seven are to be scrapped. About 85% of the new equipment is expected to be operational by the end of the third quarter in 2015, with the remainder planned to be operational before year-end.

Maintenance continues to be the bottleneck, impacting on the availability of the fleet, with a comprehensive planned maintenance strategy being developed. In the June quarter Gold Fields decided to outsource the maintenance of the fleet in Corridor 2 to equipment manufacturer Sandvik. This is expected to be implemented by November 2015 and should provide much-needed skills transfer. About 35% of ore production is sourced from Corridor 2. In addition, the new 93-level workshop, with improved facilities and excess capacity for the 2 West and 3 West corridors, is expected to be fully operational by the end of October 2015.

Progress is also being made on the different mining components.

Destress mining, of which one of the key constraints has been support installation, has resulted in eight additional support crews being deployed, which should debottleneck constraints, leading to a better second half.

Further, dedicated crews responsible for secondary support installation have been introduced and the number of rigs has increased from five in June to eight in August. All of these changes are planned to result in an increase in the rate of support installation.

A trial to convert footwall ripping to hanging-wall ripping to improve efficiencies is expected to conclude in the third quarter of 2015.

Meanwhile, backfill production increased from about 40 000 t/m at the beginning of the March 2015 quarter to about 80 000 t/m towards the end of the June quarter, which was the highest in 24 months. This was achieved through the commissioning of the full plant tailings backfill plant. This situation will be further improved through the conversion from mechanical to hydraulic mining of surface tailings, which is expected to start at the end of August.

Capital expenditure at South Deep decreased from R219-million in the March quarter to R200-million in the June quarter. The majority of this expenditure was used to upgrade the Twin Main shaft man and rockwinder, development and infrastructure, as well as on buying trackless equipment.

Key Contracts and Suppliers
Redpath (backfill piping, battrice panel installation and the replacement of South Shaft steelwork); Newrack (secondary support); TWP (metallurgical plant design); AEL Mining Services (supply of explosives for blasting) Atlas Copco and Sandvik (suppliers of HME and spares).

Previous contractors and suppliers:
Murray & Roberts Cementation (mine development and shaft deepening); Wilson Bayly Holmes-Ovcon (WBHO) and Wade Walker (tailings dam); MM&G (steelwork fabrication); Steel Services and Allied Industries, Hatch and Cadhouse Design Enterprises (ventilation shaft headgear); Howden Africa (commissioning of main surface-ventilation fans) and Sarens South Africa and Crane Corporation (overhead crane for the ventilation shaft headgear).

On Budget and on Time?
The project is on budget, but a timeline for the roll-out to steady-state production has not yet been determined.

Contact Details for Project Information
Gold Fields VP Corporate Affairs Sven Lunsche, tel +27 11 562 9763 or email media@goldfields.co.za.
Redpath, tel +27 11 974 2051.
TWP, tel +27 11 218 3000, fax +27 11 218 3100 or email twpinfo@twp.co.za.
AEL Mining Services, tel  +27 11 606 0000.
Atlas Copco, tel +27 11 821 9000.
Sandvik, tel +27 11 929 5300.

Previous contractors and suppliers:
Murray & Roberts Cementation, tel +27 11 201 5000.
MM&G, tel +27 11 914 4740.
Wade Walker, tel +27 11 466 0377.
WBHO, tel +27 11 321 7200, fax +27 11 887 4364 or email wbho@wbho.co.za.
Steel Services and Allied Industries, tel +27 18 787 2059 or fax +27 18 787 3416.
Hatch, tel +27 11 239 5300 or fax +27 11 239 5790.
Cadhouse Design Enterprises, tel + 27 16 429 1643 or email info@cadhouse.co.za.
Howden Africa, tel +27 11 240 4000, fax +27 11 493 0545 or email enquiries@howden.co.za.
Sarens South Africa, tel +27 11 861 3800, fax +27 11 861 3899 or email info@sarenssa.co.za.