The Booysendal mining right is located within the southern compartment of the eastern limb of the Bushveld Complex, approximately 35km from the town of Mashishing (formerly Lydenburg), straddling the border of Limpopo and Mpumalanga provinces in South Africa.

The property hosts the PGM-bearing UG2 and Merensky orebodies, both outcropping along an extensive strike length. The characteristics of these orebodies allow a mechanised mining approach, with relatively shallow underground mining operations, developed in a modular fashion.

Booysendal mine map

 

Key facts and statistics

The Booysendal mining right is being developed on a modular basis. The first mine established on the Booysendal concession was the Booysendal North mine. This is being followed by the Booysendal South mine.

The Booysendal North mine comprises both a UG2 and Merensky module.

Development of the UG2 module started in 2010, and a steady state production rate of 160 000 ounces was reached in October 2015. This was followed shortly thereafter by a production expansion project known as the UG2 North mine deepening project, anticipated to yield an additional 30 000 ounces by 2018.

In 2015, work started on a further expansion to the North mine with the development of the Merensky module. In the initial phase of this ‘small mine’, it will produce 25 000 ounces. Phase 2 will follow at an expanded production rate, of up to 120 000 ounces per annum. Phase 1 steady state production was achieved in July 2016. A decision on the initiation of phase 2 is pending.

The Booysendal South mine initially comprises the development of two UG2 and one Merensky mining modules producing 215 000 ounces by 2021.

Booysendal expansion (ounces)

Booysendal North UG2 mine

The North UG2 and Merensky mines are mechanised room and pillar operations. This approach is similar to that found on a number of chrome and other PGM mining operations in the region and has the following advantages:

  • A proven mining method
  • Mining flexibility
  • Safety and efficiency

The UG2 North mine reached steady state levels in H1 of the 2016 financial year, producing 160 000 ounces annually. Expansion to 190 000 4E PGM ounces commenced immediately and will be completed by the end of the 2018 financial year.

The expansion of the UG2 mine is a logical and capital-efficient extension of the original capital footprint to maximise utilisation of installed infrastructure.

The Booysendal North Merensky mine

 

Work on the Phase 1, small mine started in 2015 following successful trial mining and milling exercises. Steady state was achieved in H1 of the 2016 financial year. The labour component comprises a stoping and development crew, for establishing additional mining sections if needed. The Merensky mine is essentially a swing producer with low fixed opex.

Booysendal South project

 

This project comprises two UG2 mining modules and a small Merensky module (a similar configuration to the Merensky North mine). A focus on containing both the environmental and capital footprint has informed mine design and planning, so that the UG2 modules will be accessed via a common central portal complex. From this point, ore will be delivered to the concentrator (4.6km away) via an aerial conveyor system.

The Booysendal South project will incorporate a number of the Everest mine assets, including:

  • a 250 000 tonne per month PGM concentrator including an integrated chrome extraction plant
  • a tailings dam with capacity for eight years plus a site for an additional tailings dam
  • workshops, offices, change houses and power and water allocations
  • underground access to third and fourth South mine modules

Booysendal mine map

Geology

The Booysendal mining lease area hosts both the UG2 and Merensky PGM ore bodies, which outcrop over a strike length of 14.5km and dip at approximately 10º to the west within the area.

The Bushveld sequence at Booysendal is consistent with that found across the eastern limb. The critical zone stratigraphy is fully developed and middling between the UG2 and Merensky reefs is in the order of 175m in the northern portion of Booysendal. The sequence is subject to thinning in the southern portion, which is linked to the Bushveld rocks abutting basement highs. The impact of this 'abutment' is further manifested in disruption to surface morphology and internal structure of the two reefs.

This has led to the characterisation of three geozones within the Booysendal concession, these being the normal, slump and abutment geozones. Despite this progressive disruption to the south, the continuity of the reef surfaces is robust across the property. The internal structure of the UG2 reef is similar to that found on the Bushveld western limb, whilst the Merensky reef is typical of the northern portion of the Bushveld eastern limb.

Geological understanding of the project area is informed by data from an extensive exploration programme, comprising field mapping, diamond and percussion drilling, geophysical and geotechnical studies, complemented by underground mapping and modelling from the developing UG2 North mine.

The area is subject to some structural disturbance, in the form of dykes and jointing. These features are generally not groundwater bearing and not subject to associated extensive structural damage zones. The Merensky and UG2 reefs are separated by a stratigraphic interval of approximately 175m, and thus mining of either of the two reefs does not directly impact the other.

The Merensky reef is the upper mineralised portion of the Merensky pyroxenite, generally extending over 110cm. The Merensky reef is immediately overlain by a sequence of competent massive to partially-layered norites.

The UG2 reef consists of an upper Leader Chromitite (UL) and a lower Main Chromitite (UM) with a combined thickness of some 140cm. These seams are generally juxtaposed or merged, but can display variable internal silicate partings. The UG2 reef is immediately overlain by a competent massive pyroxenite of between 3.5-5.0m thickness, which may contain up to seven chromitite stringers/seams (UT0-UT5 and UPC).

Mining and engineering

Development of the first mining module was completed during 2013. The planned mining rate is
187 500 ore tonnes per month.

Booysendal Project map

The UG2 North mine is a mechanised room and pillar operation.

The main underground infrastructure consists of the following key elements:

  • A reverse decline system consisting of two barrels (excluding the Merensky reef access barrel). The main barrel contains the conveyor belt and chairlift for the transfer of rock and personnel. The other barrel is for the movement of mechanised equipment into and out of the mine.
  • Unique to the Booysendal design is the footwall decline which is placed some 24m below the reef horizon. This decline is connected to the reverse decline and contains the conveyor and chairlift for the conveyance of rock and personnel respectively.

Typically, room and pillar operations have the conveyor on-reef. However, in order to mitigate some of the risks emanating from power constraints, especially during peak times it was identified that some ore pass capacity was required. This buffer storage capacity will allow operations to continue on the reef horizon for up to 12 hours when the footwall conveyor is off line.

The placement of the conveyor in the footwall (ore pass capacity) generally allows for rock hoisting to surface to take place during off peak periods. This decline is developed so that it follows the positioning of the central on-reef decline to ensure the effective transfer of ore from the reef horizon to the conveyor belt system.

The north shaft complex for the first module comprises four declines, three on reef and one in the reef footwall accessed by a reverse decline.

The Booysendal concentrator plant is a typical MF2 circuit type plant and is designed to receive
187 500 ROM ore from the underground workings via the reverse decline conveying systems. A DMS plant is installed to remove 37 500 tonnes of waste from the ROM material and to improve the head grade feed to the primary mill and reduce milling requirements.

A spirals plant complete with a stockpile facility removes the saleable chrome fraction from the tailings prior to the tails thickener and the subsequent dispatch to the tailings storage facility. The final concentrate product is dried in the concentrate filter building and stored in a bin ready for loading onto a truck and shipment to the smelter.

Booysendal Project map