South Deep, Gold Fields’ Westonaria-based flagship gold mine, is coming into the ultimate stage of a four-part strategic journey it launched into in 2017 to stabilise the operation, enhance sustainability and longevity, cut back operational prices, enhance efficiencies and guarantee it meets the factors to be labeled as a mine of the longer term.
From the third quarter of 2017 to the primary quarter of 2018, Gold Fields began the journey to reshape South Deep by conducting the primary stage of the technique to determine and analyse challenges on the mine, which it plans to handle, says Gold Fields South Deep government VP Martin Preece.
“We principally broke that into three classes – social, technical and industrial – of challenges,” he says.
From the second quarter of 2018 to the top of that 12 months, Gold Fields reset South Deep, with this entailing a change from standard to mechanised strategies, enabling the orebody to be mined “basically otherwise”, says Preece.
Thereafter, Gold Fields initiated a five-step programme to stabilise and improve South Deep, which produced its first gold in 1951 because the Western Space gold mine.
Its development since 2018 concerned shaping the tradition on the mine, constructing capability by figuring out competence gaps, transferring administration and management abilities by coaching, managing work by planning and executing work to the appropriate commonplace and on the proper time. This enchancment course of additionally concerned bettering work processes by incremental enhancements, structured engagement and problem-solving, and sustaining the advance by reinforcing a regular working philosophy.
Following this, the fourth and last stage of resetting South Deep was undertaken in 2020 and can proceed till 2024, with Gold Fields aiming to develop South Deep right into a mine of the longer term that “embraces expertise, will get higher expert individuals doing higher work and ship[s] productivities”, says Preece.
These efforts, in the end, are designed to ramp up South Deep’s gold output to a gradual state of 12 t/y and reduce all-inclusive sustaining prices (AISC).
The ore mined at South Deep elevated by 36% year-on-year in 2021 to 1.54-million tonnes, whereas gold manufacturing elevated in the identical interval by 29% to 9.1 t (292 634 oz).
Gold Fields revised upwards its 2022 steering for South Deep, from a earlier vary of between 9.6 t (308 600 oz) and 9.7 t (311 800 oz), to 10 t (321 500 oz) by year-end.
As well as, the AISC have been on a downward trajectory – lowering from $1 903/oz of gold in 2018 to $1 359/oz within the first half of this 12 months – whereas South African peer gold miners’ AISC elevated throughout the identical interval.
Environment friendly Mining
Better efficiencies are additionally being attained as the main focus is shifting from the Present Mine, which lies at greater ranges within the mine, to the north of the Wrench fault line mining space (NoW), which lies at deeper ranges. South Deep is among the many deepest mines on this planet, at nearly 3 km.
South Deep’s workings are accessed from the floor by the Twin Shaft and South Shaft complexes.
The Twin Shaft contains the principle and air flow shafts, with the principle shaft being the longest single-drop shaft on this planet, reaching 110 Degree at 2 998 m, whereas the vent shaft reaches 2 947 m.
The South Shaft complicated – a subvertical system comprising three working shafts – reaches 95 Degree at 2 786 m.
The Present Mine is characterised by selective mining strategies scattered over a big space that was initially mined utilizing standard tabular mining. The Present Mine is accessed from Ranges 90, 93 and 95 utilizing the South Shaft and Twin Shaft complexes.
The NoW, immediately south and down-dip of the Present Mine, contains six mining corridors separated by regional pillars that reach southwards to the Wrench fault line. Right here, a bulk large mining methodology is used, leading to the next resources-to-reserves conversion ratio.
The South of Wrench east and west areas, located south and down-dip of the NoW, will likely be mined in the identical method because the NoW and successfully characterize a brand new mine extension to the life-of-mine footprint.
In the beginning of the reset programme in 2017, 54% of manufacturing got here from the Present Mine.
“It’s scattered and costly and doesn’t lend itself to the manufacturing facility idea of repeatability,” says Preece.
The NoW could be mined utilizing extra of a factory-type idea that’s straightforward to repeat and conduct each day.
Nevertheless, with productiveness more and more shifting to the NoW, mining groups at South Deep can entry greater-quality ore that’s cheaper to mine. In 2018, 45% of manufacturing stemmed from the Present Mine, declining to 40% in 2019, 37% in 2020, 30% in 2021 and 21% this 12 months.
Going ahead, manufacturing from the Present Mine will ramp down, contributing 19% of manufacturing in 2023, 16% in 2024 and 15% in 2025 when the NoW will comprise 85% of manufacturing.
In the meantime, with this transfer to the NoW, South Deep has additionally launched a brand new piece of progressive mining equipment – underground equipment developer TRB Elevate Borers’ Rhino 100, which is getting used to drill slot raises.
The R75-million Rhino rig requires just one operator, is powered by a John Deere diesel-powered tractor, consequently making it cellular, and is operated utilizing electrical energy that’s plugged in by underground electrical networks.
The Rhino 100 can course of as a lot as 500 m of floor a month, in line with TRB Elevate Borers.
Conventional raise-boring machines used to drill slot raises are cumbersome to maneuver and have excessive labour and time calls for, taking between two and three days to organize earlier than drilling can begin.
Alternatively, the Rhino 100 could be arrange and begin drilling inside 45 minutes of arriving at a piece web site, in line with Sandvik, which distributes the Rhino 100.
Preece says the Rhino 100 has been in use at South Deep since midyear and has since elevated the quantity of gold obtained by longhole stoping.
Initially, each stope was producing about 65% of gold contained within the stope. “[The mining teams] have pushed that north of 85%, and the Rhino rig goes to enhance our skill to get to the total top [of the longhole stope] to attempt to get nearer to 95% of the gold,” he provides.
Sustainable Mining
Gold Fields has additionally made a major effort to extend the sustainability of South Deep, a major instance being the profitable endeavour to fee its R715-million, 50 MW photo voltaic photovoltaic (PV) farm – the 105 ha Khanyisa photo voltaic plant.
The plant is so expansive that South Deep runs a voluntary, however well-attended, weekly 5 km (single lap) enjoyable run across the perimeter fence, which additionally serves as a team- constructing train for workers.
South Deep makes use of about 494 GWh of electrical energy a 12 months, representing about 10% of the mine’s yearly prices and about 93% of its carbon emissions.
The plant, totally commissioned in October, can generate about 103 GWh a 12 months, thereby helping in lowering vitality prices by saving about R123-million (24%) in such prices a 12 months.
Gold Fields has regulatory approval to broaden the plant by one other 10 MW, which could be undertaken by merely putting in extra panels, for which the associated infrastructure already exists.
Going ahead, South Deep’s vitality groups are assessing the place the electrical energy generated by the photo voltaic plant could be most successfully built-in to make sure that none goes to waste, therefore the corporate’s investigating the feasibility of placing sure continuously operated and constantly power-intensive gadgets of kit – reminiscent of air flow followers, refrigeration vegetation, pumps and compressors – on to solar energy.
When it comes to success, Preece states that the photo voltaic mission was the best capital mission he has ever needed to encourage to the Gold Fields board. Within the South African context, he says photo voltaic PV presents nice returns and gives enterprise continuity.
South Deep can be investigating introducing wind generators after preliminary exams indicated the potential to take advantage of a wind useful resource prevalent in a particular area of the mine lease space.
“With [the way in which] wind generators have developed through the years, we see some potential to place up some wind generators. We’re placing up a wind mast. Preliminary indications are that there’s a viable supply of wind that we will harvest to enrich the photo voltaic panels,” says Preece.
Additional, the mine can be utilizing undergound electrical autos (EVs) and can take supply of its first electrical loader earlier than year-end.
The adoption of EVs is beginning gradual to permit for extra time to excellent the mixing course of and decide what kind of EV will work greatest. When it finds one of the best answer, South Deep plans to quickly substitute designated underground autos with electrical models. Additionally it is contemplating above-ground EVs.
A serious advantage of deploying EVs underground is a major discount in warmth loading in vehicle-intensive areas due to the huge volumes of warmth generated by diesel engines. There are additionally main advantages when it comes to cutting down air flow techniques, as exhaust emissions are eradicated.
EVs additionally cut back the quantity of lubricants used. “There [are] actually productiveness enhancements and value enhancements. It’s actually fascinating as a result of [EVs] truly require much less upkeep, which is form of counterintuitive,” Preece concludes.
