The story of a little gold mine

Metalurgical engineer, Minette Bezuidenhout processes 200 rock smaples daily to determine where mining activities must focus.

NELSPRUIT – It is not a glamorous job and you often need a will of iron to mine gold. This Mike McChesney and Mike Begg from local mining company, Vantage Goldfields can tell you. They will also tell you that, contrary to the common perception, a gold mine is not always, well, a gold mine. Especially for a “small mining company that is still growing,” as Begg describes Vantage.

General manager of Vantage Goldfields mines, Mike Begg, in front of the Lily mine near Louisville.

General manager of Vantage Goldfields mines, Mike Begg, in front of the Lily mine near Louisville.

Vantage Goldfields SA, of which McChesney is the CEO, was listed on the Australian Stock Exchange in 2010 and currently owns two productive mines located in the Barberton green stone, namely the Lily and Taylor (in the Barbrook Mines complex) mines.

The Barbrook complex and plant was acquired from a Canadian company in 2008. Another 12 potential mining projects in the region forms part of the future prospects of this junior mining company. Begg, mine manager for Vantage, has worked in the areas since 1985 when he first walked the hills as a geologist. McChesney has been mining here for over 25 years including at the Makonjwaan and Worcester mines.

Information nuggets

Gold deposits are spread throughout the area’s greenstone belt and the bushy hills are literally dotted with old mine shafts dating back to the 1800s.

• In general terms, the size of a mine is expressed in the tons of rock it mines per month. For example, Lily produces 32 000 tons per month (tpm) at 3 grams per ton and Taylor mine at the Barbrook complex produces 9 500 tpm at 4 grams per ton.

• Together, Lily and Barbrook represent almost 4 million ounces of gold that still needs to be mined.

• Taylors mine will go from 9 500 tpm to 25 000 tpm, and then in next stage up 50 000 tpm

• Lily  is pretty much at full capacity at 32 000 tpm  and with some tweaks could go up to 35 000 tpm

• One standard truck load of rock driven to the plant for processing equals 22 tons of ore and $1 500 worth of gold.

Barbrook mining complex

Barbrook mining complex

• 200 samples of rock are processed daily at the Barbrook metallurgical centre to determine in which direction mining operations should be steered

• Daily mining activities underground consists of a blasting followed by removal of the rock. It costs R15 000 per metre to tunnel and they currently mine at a rate of 380 to 400 metres per month.

• Due to the different sulphates present in the rock at Lily and Barbrook respectively, two different lines had to be erected in the processing plant to extract the gold.

 Environmental management

The biggest threat the environment posed by gold mining comes from the so-called slurry containing cyanide which is used to extract gold from the ore. Cyanide is used to extract gold from ore. This is done by leaching the rock on lined pads or by crushing the rock to the consistency of sand (milling), then adding water to form a slurry.

The slurry is mixed with a cyanide solution; gold particles bond with the cyanide in solution and are extracted from the slurry.

The management and disposal of cyanide solutions used to dissolve and extract gold from ore is an environmental concern. Cyanide is a well-known poison; hydrogen cyanide is acutely toxic to humans in its gaseous state and can be fatal at exposure levels of 100 to 300 parts per million (ppm).

Cyanide is also harmful to wildlife; mammals, birds and fish all have acute toxicity reactions to even low cyanide exposures. Cyanide does not, however, accumulate or biomagnify, so prolonged exposure to sub-toxic levels does not, in most cases, appear to pose health risks.

There are two significant environmental risks from cyanide solutions used in gold mining. The first is the possible leaching into soil and ground water at toxic concentrations; the second is the risk of catastrophic spills that might inundate an ecosystem with toxic levels of cyanide.

At the Barbrook plant, slurry is carried uphill via a pipeline to a slurry dam where it is contained. Once mining activity at a specific place ceases, slurry dams are covered with soil. Barbrook has experienced two slurry spills in the past seven years.

According to Begg, their response to these were, on both occasions (2006 and 2013) speedy and no large scale environmental damage resulted. Mimco (the Vanatage subsidiary that manages the Lily mine) general manager, Begg, acknowledges the delicate environment of the Lomshiyo Valley.

He says, “We have operated in this valley for over 25 years and take our responsibility of interacting and protecting this environment seriously. We continually consider endeavours to prevent any situation that may jeopardise this relationship. However, accidents like this can occur despite our best intentions and endeavours. We believe that we managed the problem and any immediate affects speedily and responsibly.”

Water resources that can potentially be contaminated by slurry spills here is limited to te Sofala River, which feeds into a canal. According to Begg water from the Sofala is not safe for human consumption due to daily pollution by residents of the valley. Opencast mines are rehabilitated to the same condition as the landscape surrounding its when mining operations stop.

Economic contribution to the Lowveld economy

The collective figures for Vantage Goldfields and Barberton Mines include:

• Total employees in 2012 of 2 404

• Salaries of R433m

• Stores spend in Lowveld of R432m

• Community spending of R15m.

Local community projects

From day-care centres to spraying the gravel road, Vantage invests in the community of the Lomshiyo Valley, says Begg. Road maintenance alone costs around R200 000 per month, and, he explains, the locals can get quite upset if the road is not kept dust-free.

Another R3 000 to R4 000 per month is contributed toward cleaning products for the Sinqobile School, and they will soon assist with the construction of an office block for the school. “We also help with providing water, grading roads and regular soup kitchens for the elderly. Our valley needs us, and we need it.”

Most of their 800 employees live either in the valley or nearby in Matsulu.

Future projects Apart from further exploration and mine development along the 25km Barbrook complex, they are also investigating the possibility of adding a Biox plant to their local operations.

Biox is a process used around the world, and locally at Barberton Mines’ Fairview plant, to recover gold from ore. It increases gold recovery by destroying sulphide minerals through which cyanide struggles to reach. Pretreated in a Biox plant, more of the mineral can be extracted. The process utilises a mixed population of bacteria to break down the sulphides.

Fairview near Barberton was the first application of the Biox technology worldwide in 1986. Expansion of mining is in the pipeline for Vantage. Beggs says it wants to increase its operations at Lily mine from 8 000 to 20 000 tons per month, and to 50 000pm at Barbrook.

IMG_8339_517739800

Mike Begg, general manager of Vanatage Goldfield's South African mines, at what he describes as the heart of the operation, where ore is crushed to a powder fine enough for extraction.

Mike Begg, general manager of Vanatage Goldfield’s South African mines, at what he describes as the heart of the operation, where ore is crushed to a powder fine enough for extraction.

Begg explains a part of the gold extraction process

  AUTHOR
Susanna Oosthuizen
Journalist

Latest News

COMMENTS

Top
Recommended Story x
Farm attack: Man begged for life