Remember Burnstone

By | 2019-03-20T11:29:43+00:00 March 8th, 2019|Mining in Focus|

There has been a lot of talk about mechanisation, but mechanisation has failed in certain instances, writes Leon Louw.

My first mine excursion to the Burnstone gold mine was in early 2011. Burnstone is about 80km south-east of Johannesburg, near the town of Balfour in Mpumalanga. At the time, it was owned by Canadian outfit Great Basin Gold (GBG). In January 2011, a large group of journalists and investors was welcomed with great fanfare at the opening of this state-of-the-art mining development. And it was impressive. Most activities were mechanised, with massive development work adjacent to the reef to allow access for equipment needed to haul out the ore and material.

The mining method adopted at Burnstone was long-hole stoping. Material was to be mechanically transported to the surface stockpile near the portal, where it was collected for transport to the plant or waste dump.

Long-hole stoping is a highly selective and productive method of mining and can cater for varying ore thicknesses and dips (0 to 90 degrees). After the blasting phase in the stope, the blasted rock would fall into supported drawpoints where it would be removed with load, haul, and dump machines, which means workers didn’t access the stope during this time. Burnstone looked impressive indeed.

However, when we visited the mine about a year later, at the start of 2012, the group was noticeably smaller, and it was clear that the mining team had run into some trouble. The visit was organised by GBG as a damage control exercise, and after speaking to the management team, we knew that the writing was on the wall. The cost of development was just too exorbitant. The mine was spending too much money just to get onto the reef and to get the equipment underground. Furthermore, there were numerous structural faults that the mine planners never foresaw, and water ingress that wasn’t planned for. Basically, the ore body didn’t lend itself to the mining method being employed, and the underground mining team had to overcome too many geological challenges.

Nonetheless, the deposit (Kimberley reef) was a good one with huge potential. In 2013, there were a number of interested parties of the opinion that they could turn the fortunes of the mine around. The most vocal was Philip Kotze, then CEO of the JSE-listed Witwatersrand Consolidated Gold Resources (Wits Gold), who didn’t mince his words, and opined that the mine lends itself to conventional mining methods, rather than mechanised methods. Wits Gold put in a bid to acquire the mine, but in the end, Sibanye Gold (today Sibanye-Stillwater), on an acquisition spree under CEO Neal Froneman, bought the Burnstone assets in July 2014, after the mine had been in care and maintenance for close to two years.

Drilling at the beleaguered Burnstone Mine in 2012.

Drilling at the beleaguered Burnstone Mine in 2012. Image credit: Leon Louw

Sibanye’s assets included two shaft complexes — the surface portal and mechanised vehicle access decline, and the vertical shaft (shaft bottom at 495m below surface) — as well as a 125 000 tonnes per month (tpm) gold processing plant, the tailings storage facility and surface infrastructure to support a producing operation, albeit with areas still to be constructed.

Before being placed on care and maintenance, Burnstone produced about 38 000 ounces (oz) of gold. The feasibility study for Sibanye-Stillwater’s Burnstone project was approved by the board for project execution in November 2015.

According to the company’s website, the project is planned with a six-year build-up to steady-state production by 2022, then averaging 125 000oz annually for seven years until the end of 2028. Thereafter, a seven-year period of decreasing but profitable production supports an initial 20-year life-of-mine (LoM) plan, yielding some 1.9 million ounces (Moz) of gold production from the feasibility resource of 5.7Moz.

This initial LoM plan was limited to about 60% of the total Burnstone resource of 8.9Moz as the mine design and schedule in the feasibility study was limited to mineable reserves within a 3km radius of the shaft infrastructure. During steady-state production, the potential of the 3.2Moz resource excluded from the initial LoM plan will be evaluated.

Burnstone re-evaluated and declared 1.934Moz of mineral reserves and 9.015Moz of mineral resources as at 31 December 2017.

The company said in a statement in 2017 that the following advances were made at Burnstone at a cost of R395-million:

  • Delivered 5073m of access development;
  • Shaft Tip 3 construction was completed;
  • Conventional raise development crews were initiated.

Geological difficulties and water ingress continue to hamper development at the mine. At the end of 2017, Sibanye said that numerous water intersections (fissure water) were intercepted.

“These intersections delayed development; however, a comprehensive water handling plan has been implemented to minimise any delays in production going forward,” the company stated. It has to be asked whether Burnstone will ever live up to the expectations and become a top gold producer in South Africa, or has too much damage been done to get the operation back on its feet again?