Platinum producer Anglo American Platinum’s (Amplats’) underlying production from its South African and joint venture (JV) mines fell by 5% or about 110 000 oz to 2.28-million ounces last year, according to platinum-group metals (PGMs) distributor Johnson Matthey’s 2012 platinum report.
Safety stoppages were the primary cause of the shortfall and the underlying mine output is expected to rise, notes Johnson Matthey. To improve production levels, Amplats has established many projects over the years at its various fully owned mines and JV mines.
However, operations at Amplats and its JV partner Aquarius Platinum’s Marikana mine, in the North West province, were suspended earlier this month as a result of the continuing low price of PGMs. The mine was placed under care and maintenance to preserve the ore reserves until conditions improved.
The operation holds a reserve of about 1.44-million PGM ounces.
Meanwhile, some of Amplats’ other ongoing projects include the 10 West project at the Tumela mine, in Limpopo, which entails the deepening of the existing 10 West decline system, the 16 West belt decline and the Dishaba mine’s East Upper upper group two (UG2) project, which uses existing Merensky reef infrastructure at Dishaba No 2 shaft to access the UG2 reef horizon. The project started in 2007 and was completed in 2011.
The backfill project at Tumela, which began in 2004 but was deferred in 2008, restarted in 2011. The expected capital expen- diture is R150-million, and its completion is planned for the fourth quarter of 2013.
Further, a feasibility study is in progress for the Merensky deepening project at the Siphumelele 1 shaft, in the North West province. The project involves the extension of the current decline clusters between 35 level and 37 level. This will extend the life-of-mine by five years, adding 0.91-million ounces to the production plan. The project is scheduled for implementation in the second quarter of 2013.
Meanwhile, Amplats’ Twickenham platinum mine project, in Limpopo, will contribute 180 000 oz/y of refined platinum by 2019 when it reaches steady-state production. The project consists of two decline shaft complexes and a concentrator, and forms part of a production decision to expand Amplats’ current operations on the eastern limb of the Bushveld Complex.
Amplats has approved R7.1-billion to develop the project, as the complete Twickenham project investment approval is expected in the last quarter of this year. This will include the concentrator, for which a feasibility study has been completed.
Development ore is being stockpiled and the concentrator is planned for commissioning in 2016, in line with the project’s production plan.
Work on the Twickenham project is reportedly progressing well and is expected to gain momentum after being delayed by three years owing to unfavourable economic conditions.
The construction projects of the Twicken-ham and Hackney decline shaft complexes have started as of this year. The declines will be extended to 650 m below surface; at this depth, refrigeration will be implemented. Each shaft reportedly consists of three barrels located in the footwall.
Another key feature of the project scope includes the approved life-of-mine footprint, which extends down to Level 7, with 11.6 km on strike. The footwall infrastructure and on-reef excavations are being developed to open 250 000 t/m of stoping reserves on ten operating half-levels.
Stoping of the reef will use the well-proven methods of breast mining with face scraping, as currently used by the Bokoni platinum mine.
Further, battery-powered locomotives and hoppers will collect the broken ore on each level and deliver it to the station tips, from where it will be transferred by a series of decline conveyors to surface silos. From the silos, 33 t on-highway trucks and trailers will be used to transport the ore to the concentrator.
Meanwhile, surface- and underground-engineering infra- structure will be required to facilitate a nonpneumatic mining strategy with hydraulic-powered drilling and loading equipment used for primary off-reef development. Drilling for drop-raising is also performed by hydraulically powered rigs.
The central area at Twicken-ham comprises the bulk infrastructure for potable water, raw water and sewage. State-owned power utility Eskom’s electricity-supply centre will be based at the central area, as well as the electricity reticulation, buildings for protection services and the medical facility for the Twickenham business unit.
Meanwhile, the Dishaba mine’s East Upper UG2 project at the Bushveld Complex is set to raise Amplats’ refined platinum production capacity by 100 000 oz/y.
The project will mine the UG2 reef using existing mining infrastructure, previously employed to mine the Merensky reef at the vertical No 2 shaft and three decline shafts at 44 East (E), 50 E and 62 E.
The recently completed 75 000 t/m UG2 concentrator will be expanded to 210 000 t/m.
As a consequence of the tonnage increase, a new tailings dam, a holding dam and an upgraded tailings handling and pumping system are required.
The project has a capital cost of R1.57-billion. This comprises R693-million for the concentrator expansion and R875-million for UG2 ore-reserve development and the mining infrastructure upgrade.
Project implementation started in 2007. Development of the ore reserve took 18 months and steady-rate production is expected this year.
According to Johnson Matthey’s report, the Amplats JV’s impact on production was limited, despite being affected by Section 54 stoppages in the fourth quarter of 2011.
Production at Amplats’ Bafokeng Rasimone platinum mine (BRPM) decreased by 2% to 180 000 oz of platinum, says Johnson Matthey.
Amplats aims to increase the levels of Merensky production at the mine’s North shaft through its Phase 3 project.
The R1.27-billion project will provide access to 1.41-million Merensky platinum, palladium, rhodium and gold (4E PGM) ounces.
The project will also extend the existing decline shaft by adding five levels from Level 11 to Level 15. This will provide further replacement for Merensky production at the North shaft complex. At steady-state production, the project will contribute 70 000 oz/y.
The project has started and will span about seven years, and construction is scheduled for completion in the third quarter of 2015.
In February, the mine’s JV partner, Royal Bafokeng Plat- inum, reported that the project continued to make steady progress and remained on track for the scheduled completion date.
The Royal Bafokeng Platinum board of directors has approved the expansion capital project relating to the North shaft Phase 3 project on the BRPM, following the conclusion of a feasibility study.
Meanwhile, Amplats’ JV Bokoni platinum mine, together with platinum junior Anooraq Resources, on the north-eastern limb of the Bushveld Complex, has a current mining rate of about 80 000 t/m, with an average grade of 4.3 g/t.
The production is split between the Merensky and UG2 reefs at 50 000 t/m and 30 000 t/m respectively and, once processed, yields about 150 000 oz/y of 4E PGMs. Bokoni is the only eastern limb operation whose Merensky production is significantly high in platinum value, with a 2:1 platinum to palladium ratio and a high UG2 reserve grade of 5.63 g/t 4E PGMs.
The Bokoni property consists of seven mining licences covering an area of about 15 000 ha.
Bokoni’s maximum value is achieved at a mining rate of 375 000 t/m, comprising steady-state Merensky reef production of 120 000 t/m and steady-state UG2 reef production of 255 000 t/m. The long-term growth plan for Bokoni is planned over two stages.
Stage 1 comprises an expansion of Merensky and UG2 reef ore production to 160 000 t/m, with Merensky reef production being increased to 120 000 t/m (primarily from the Brakfontein Merensky reef decline shaft system) and UG2 reef production being maintained at 40 000 t/m (from the Middelpunt Hill UG2 reef decline shaft system).
Stage 2 considers further expansion of UG2 reef production to 255 000 t/m, while Merensky reef production will remain at 120 000 t/m.
The Stage 1 and Stage 2 expansions are intended to access the Merensky and UG2 reefs from near surface to about 650 m below surface. This represents a key technical and cost advantage, as there will be no need for significant refrigeration at these mining depths.
The value of the project is R2.6-billion. Construction of Stage 1 began in 2009 and its completion is expected in 2014, while Stage 2 is expected to begin in 2016.
Amplats’ Styldrift Merensky Phase 1 project, in the North West province, will exploit one of the last major Merensky mining blocks on the western Bushveld Complex. Amplats aims to extract about 68-million tons during the life of the mining operation, between 2016 and 2043.
The mine, another JV with Royal Bafokeng Platinum, will process 230 000 t/m of Merensky reef at steady state.
The project will deliver an underground operation, which will be accessed through a twin vertical shaft system – the main shaft will be sunk to 740 m and the service shaft to 705 m. Initially, wide-reef trackless mining methods will be implemented, followed by narrow-reef conventional mining methods.
The Styldrift project site is about 5.5 km from the existing BRPM concentrator and an overland conveying system will be constructed to transport the ore to the concentrator.
During steady-state operation, the mine will produce about 220 000 oz/y of platinum, effectively doubling BRPM’s platinum ounce production to about 400 000 oz/y.
Shaft site infrastructure will comprise the twin shaft system, associated mining surface infrastructure and the waste rock dumps. No tailings dam will be built at the project site; however, an extension to the existing tailings dam will be constructed to accommodate the tailings from the BRPM and Styldrift concentrators.
The R11.8-billion project was approved by the boards of Amplats and Royal Bafokeng Holdings in the third quarter of 2008. First production is expected to start in the second quarter of 2015, while steady-state production is expected by the second quarter of 2017.
Royal Bafokeng Platinum remains confident about its Styldrift Phase 1 project and is looking forward to intersecting the Merensky reef towards the end of this year.
The project remains on course to save R1-billion on completion and, to date, has declared savings of R323-million. After a slow start in early 2012, significant improvements have been realised on the rates of shaft sinking at Styldrift and the expected shaft advance rates will be achieved. The main shaft reached 219 m and the service shaft 152 m by the end of 2011.
Ore Replacement Project
The Khuseleka ore replacement project, in the North West province, will see the replacement of 70 000 oz/y of platinum from 2015, and forms part of the strategic approach of Amplats’ Rustenburg Section mine to tackle the declining Merensky reef reserves.
The ore replacement project will allow Amplats to safely exploit the UG2 reserve in the Khuseleka decline shaft and make optimal use of the overall ore tonnage capacity at Khuseleka.
It also allows for a major extension of mine life. The project has, however, created a demand for additional ventilation in the lower decline area, which will be met by a new, dedicated downcast shaft system carrying 600 kg/s of air, with 8 MW of surface bulk cooling.
The three ventilation shafts will intersect the decline system on 26 level, about 821 m below surface.
These shafts, which are sited about 3 km from the main Khuseleka vertical shaft, have been completed.
The project also involves providing a surface refrigeration plant, which involves underground development to access the Merensky and UG2 resources and the infrastructure required to facilitate extraction of the reserves.
The ore reserves are being accessed through the existing Merensky decline cluster section, with the Merensky ore mined from 25 level to 28 level and the UG2 ore being extracted from levels 15 to 28.
The project is valued at R1-billion and is expected to be completed in 2015.
Amplats reported in 2010 that the project was 53% complete and might be finalised in the fourth quarter of 2015.
Meanwhile, the Thembelani No 2 shaft platinum replacement project, in the North West province, will gain access to deeper Merensky reef reserves at a rate of 120 000 oz/y.
The R2.3-billion project is the first of this magnitude in more than a decade, and includes a downcast vertical men-and- materials shaft and an adjacent matching vertical upcast ventilation shaft, which will intersect the existing horizontal connections. It will also involve the extension of the existing declines at the Thembelani No 1 shaft project.
The proposed vertical men-and-materials shaft will access declines on the 28, 32 and 33 level elevations and the upcast vertical ventilation shaft will access declines on the 28 and 31 level elevations. The surface infrastructure will include a standard shaft bank layout, a dedicated refrigeration plant, a supply chain store, offices, change houses and a compressor station (which is not required should electrical drilling be selected).
Bulk services will include overhead power lines, road access, sewage reticulation and water-supply pipelines to the new Paardekraal 2 shaft.
Production of 120 000 oz/y of refined platinum is expected by 2015.
Amplats has reported that further evaluation assessments are under way at the Thembelani No 2 shaft project, while a comprehensive proposal to continue with its full development will be finalised during the 2012 financial year.
Production from the early levels 27/29 started in 2008 and about 47 000 oz has been produced. The capital development and equipping of 29 level is almost complete.
The ventilation shaft has been sunk to its bottom 31 station and is complete. Initial ore reserves development from the ventilation shaft started in 2011 for early access to levels 30 and 31. This was made possible by the commissioning of temporary hoisting facilities in the ventilation shaft.
Bulk infrastructure, such as the refrigeration plant, the consumer substation, the 1 kV substation and the 3 kV yard, was also commissioned in 2011. The main shaft is now sunk to 33 level (1 117 m below surface), station cutting is under way, and 28 level and 32 level have been completed.
Given the current global uncer- tainty, development of the shaft is to be stopped at 33 level. Further option studies will be conducted during this year to define the optimal configuration for extrac- tion below the current shaft bottom.
Amplats has reported that the project is on track to be com- pleted on time and within budget.