Name of the Project
Witwatersrand Basin project (WBP).
Location
At the northern edge of the Witwatersrand basin, in the Central Rand Goldfield, immediately south-west of the City of Johannesburg, in Gauteng, South Africa.
Project Owner/s
West Wits Mining.
Project Description
A scoping study has demonstrated the WBP’s potential to be West Wits’ cornerstone project, with average steady-state production of 80 000 oz/y for 18 years and a life-of-mine (LoM) of more than 20 years. The study is underpinned by WBP’s global 3.55-million-ounce Joint Ore Reserves Committee-complaint resource, which covers the project’s mining footprint.
The study has identified five distinct reef packages for mine development – Qala Shallows (Shallows), Main Reef (MR), Bird Reef East (BRE), Bird Reef Central (BRC) and Qala Deeps (Deeps).
The WBP has the potential to build up to a peak production rate exceeding 95 000 oz/y, with production target averages of 90 000 oz from Year 6 to 11 as production reaches steady state from the Shallows, Main Reef and BRE packages. The study envisages estimated production from the Shallows section at 5.7-million tonnes, at a run-of-mine grade of 3.4 g/t for 630 000 oz over 13 years of production and steady-state production of about 60 000 oz/y for six years.
First production from the Shallows is expected in Year 2, with a build-up to 50 000 t a month early in Year 4.
The MR, comprising the MR and MR Leader bands, has been identified for the second stage of development and is a priority target, owing to the high recovered gold grade of 5.3 g/t.
The MR section will provide an estimated 630 000 t at 5.3g/t gold for 105 000 oz of incremental production over Year 4 to 9 combined. Access to the MR package is planned from the existing No 6 shaft site. The next stage of feasibility for the MR will also assess the potential of continuing development from the BRE area, only 1 km to the north, as an alternative access point to the MR package as a further optimisation.
Stage 3 involves the development of BRE, with Bara planning access off the Shallows decline; the mine layout provides access to the BRE through the development from the Qala shaft. Once the Shallows operation reaches an estimated depth of 150 m and nears steady-state production, a drive will be established to the BRE, with a development distance of 1 km.
BRC is accessible through the existing Circular shaft, which involves the development of the Qala infrastructure, situated about 3 km to the east. Combined with the lower recovered grade profile relative to the WBP’s other areas of development, the BRC is scheduled for development after the MR and BRC, and is also subject to further feasibility.
The Deeps area is a depth extension of the Shallows from 500 m to 1 500 m below surface, where the reef dip steepens from 40 º at surface to 70 º at depth. The water table floods historical mine works at about 200 m below surface. A geotechnical report supporting the scoping study found that leaving a water pillar, with a width-to-height ratio of 15:1, allows for access to unmined areas at depth, which is applicable to the Deeps’ targeted mineral resources. Production from the Deeps is scheduled to ramp up to steady-state production from Year 15 as the Shallows nears depletion. The Deeps will share infrastructure access with the Shallows and will be subject to a dedicated definitive feasibility study (DFS) to confirm rock support and ventilation requirements to achieve the WBP’s production schedule from Year 15.
The scoping study has used a narrow-reef breast mining method in the upper sections of the conceptual mine plan, which is the same mining method being used when the historical mine ceased in the early 2000s. This method is still being used extensively in South African gold mining.
The scoping study indicates that there is enough capacity and quality of processing in the region to enter a toll treating arrangement with one of the local process plant operators as opposed to allocating capital expenditure to the construction and operation of a process facility.
Potential Job Creation
Not stated.
Net Present Value/Internal Rate of Return
Not stated.
Capital Expenditure
Not stated.
Planned Start/End Date
Not stated.
Latest Developments
The first stage of WBP’s development, the Shallows area, has advanced to DFS stage, which is due for completion by the of August 2021. The Shallows provides about 70% of production tonnes in WBP’s initial nine-year production period and about 46% over WBP’s 25-year LoM.
West Wits intends to start with the rehabilitation and recommissioning of the existing boxcut at the Qala shaft. The decline will be widened in certain areas to accommodate trucks underground, which will be used for mineral resources and waste transport. This will provide access to the old workings and the starting position of the new decline.
During the recommissioning phase, a technical services team will access the old workings to conduct geological and rock engineering surveys, also identifying potential old workings that can be restarted as an early mining initiative. This early mining initiative has not been included in the production profile, so it will be in addition to the report’s production target, if achieved.
While the early mining initiative is in progress, the project team will start with the development of the underground infrastructure and construction of surface infrastructure.
During the scheduled development of the Qala shaft, the engineering team will further review the access and production schedules of the MR and BRE, which will be subjected to further DFSs, due to start in the fourth quarter of 2021 and the first quarter of 2022 respectively. The studies will underpin the final investment decision to start Stage 2 and 3 of the scoping study’s development schedule.
Key Contracts, Suppliers and Consultants
Bara Consulting (scoping study).
Contact Details for Project Information
West Wits Mining, tel +61 3 8692 9049 or email info@westwitsmining.com.