In 1970 three exploration holes were drilled by Johannesburg Consolidate Investments Co. Ltd (JCI). After a 20-year hiatus, drilling continued from 1990 to 2001, during which time 48 boreholes were drilled. In 1980 JCI undertook additional exploration campaigns at Styldrift and intersected UG2 for the first time.
Drilling campaigns started on Frischgewaagd in 1970 and between 1992 and 1998, nine boreholes were drilled on the property. Between 2005 and 2008, a total of 111 boreholes were drilled on Styldrift. During this period pre-feasibility studies (focusing on Merensky Reef extraction) were undertaken on both Frischgewaagd and Styldrift.
The Styldrift I shaft complex lies about 5km from Bafokeng Rasimone Platinum Mine’s (BRPM) North Shaft. The feasibility study on the Styldrift I Project was approved in September 2008 by the joint venture (JV) partners and bulk earthworks started in March 2009 and extend over a 17-hectare footprint.The project will process Merensky ore via a new twin shaft system which is being sunk to a depth of 740m. Mining will be undertaken through a combination of mechanised bord and pillar mining with conventional mining methods introduced in later years. Production at 230kt a month is expected from the third quarter of 2018.
During 2012 we completed the concept study initiated in 2011 and updated the geological model with the exploration drilling data accumulated from the 2011 exploration drilling programme. Updating the geological model has resulted in an improvement in our overall resource confidence levels to the extent that they can support both pre-feasibility and feasibility study work. It also confirmed the lateral grade continuity and consistency of the mineralised envelope.
The outcome of the concept study was presented to the RBPlat Executive Committee and approval was granted to proceed with the pre-feasibility study which we expect to take approximately 18 months and we anticipate completing during the first half of 2014. To further enhance our understanding of the ore body in the project we are planning to drill an additional 27,000 metres in 2013.
Power and water supplies have been secured for the life of mine from Eskom and Magalies Water respectively. Both BRPM and the Styldrift I Project have modern access roads, and the necessary infrastructure to conduct mining successfully.
To reduce dependency on the existing Magalies water supply, all excess water produced by mining operations at Styldrift will be pumped to the BRPM concentrator complex and reused for ore processing.
A 1.2km gravel road will provide a link between the project site and the existing access road during the construction phase, and will be upgraded to a permanent tarred road. A second gravel road will form a service link along the conveyor service corridor and connect the BRPM complex to the Styldrift mine.
Access to the underground workings will be via a twin, concrete-lined vertical shaft system comprising a 10.5m-diameter Main shaft and a 6.5m-diameter Services shaft, blind sunk to a depth of 740m and 705m respectively. Footwall infrastructure, mainly for the transporting of ore to the shaft, will be developed approximately 25m below the Merensky reef horizon. Two 22-tonne rock skips will be used to hoist the ore to the surface via the Main shaft. A second footwall network will be developed at 690m level, at the base of the UG2 horizon, for potential concurrent exploitation of the UG2 reef.
The shaft system will be linked to the up-dip and down-dip on-reef roadway clusters on both the reef horizon and the footwall level. A network of on-strike haulages will underlie all sections for the transportation of ore to the Main shaft.
Situated 25m below the Merensky reef horizon, the Merensky footwall is the main artery of the proposed mine. Apart from travelling ways, all footwall infrastructure will be mechanically developed. This infrastructure includes tipping points on the reef horizon, from which ore will be sent via boxholes to the trucking haulage points 25m below. Fifty-tonne diesel-powered trucks will then transport the ore to ore passes feeding an underlying conveyor belt system 18m below. The conveyor system will include the main conveyor belt decline and an adjacent auxiliary decline.
The orebody lends itself to a combination of mechanised Room & Pillar and conventional breast stoping. The mechanised mining method will be bord and pillar. Each trackless mining section will consist of 9 panels and 8 pillars. The primary extraction layout was originally designed to be 13m wide rooms separated by pillars which are 12m wide and 12m in length, however the bord widths are currently being reviewed and will most likely be reduced to 8m. Ventilation holings are mined between panels within the mining sections and are 6.5m wide. Regional (17m wide) pillars will separate the mining sections. On reaching the stope limit, partial secondary pillar extraction will be undertaken using remote controlled equipment resulting in 12m by 4m crush pillars being left in secondary mining areas. The secondary crush pillars are designed to fall within the width/height ratio of 1.8:1 and 2.5:1. In the very thick reef areas, where reef thickness reaches 3.2 m these secondary crush pillars will be increased to 12m by 6m.
Both primary and secondary extraction may be adjusted locally in areas where poor ground conditions exist. This may involve reduced primary bord widths and/or selective secondary extraction.
The shaft infrastructure comprises a main shaft with a diameter of 10.5m sunk to a depth of 740m and a services shaft with a diameter of 6.5m sunk to a depth of 705m below surface.
The configuration of the Main shaft allows for the following:
The Services shaft will comprise a personnel and equipment cage compartment with capacity to transport 22 people, as well as a cage counterweight compartment.
Four winders will be used during the project construction phase and three during the production phase. The height of the Main shaft headgear is 58.6m and the Service shaft 41.3m.
The concentrator capacity at Styldrift will be 2.76 million tonnes per annum. Surface earthworks for the Styldrift I Project began in 2009. Ramp up is planned for 2015 and steady state production anticipated by 2017. At steady state, the Styldrift I Project will increase the BRPM JV production to 430,000 tonnes per month with in excess of 400,000 ounces of platinum concentrate per annum being produced by the BRPM JV.
3D rendering of the main and services shaft headgear
The feasibility study on the Styldrift I Project was approved in September 2008 with the development of site infrastructure commencing in March 2009. With the project ahead of schedule, shaft sinking commenced in the fourth quarter of 2010. The Main and Services shafts both reached a depth of 600m by the end of August and October respectively.
Styldrift remains on schedule to commence production in 2015 and to ramp up to full production in 2018. We expect the overall joint venture head grade to benefit from the Styldrift Merensky contribution from 2016 and to increase to between 4.25g/t (4E) and 4.30g/t (4E).
Further detail is provided in the review of our projects of our Annual Report 2012. (PDF - 425KB)
The Styldrift II Project, an exploration project with organic growth potential, is a key component of the future growth strategy of RBPlat.
It has a resource area covering approximately 24 million square metres varying in depth between 900 and 1,500 metres, at an average dip of 90 and accounts for 40% of the total BRPM JV resource. Unique to the project area is the fact that the Merensky resource is exclusively underlain by the Swartklip Facies, which is generally characterised by improved lateral continuity of grade and consistency in the mineralised envelope width, when compared to the Rustenburg Facies found on BRPM and Styldrift I.
During 2012 we completed the concept study initiated in 2011 and updated the geological model with the exploration drilling data accumulated from the 2011 exploration drilling programme.
Updating the geological model has resulted in an improvement in our overall resource confidence levels to the extent that they can support both pre-feasibility and feasibility study work. It also confirmed the lateral grade continuity and consistency of the mineralised envelope.
The outcome of the concept study was presented to the RBPlat Executive Committee and approval was granted to proceed with the pre-feasibility study which we expect to take approximately 18 months and we anticipate completing during the first half of 2014.
To further enhance our understanding of the ore body in the project we are planning to drill an additional 27,000m in 2013.