JOHANNESBURG (miningweekly.com) – Dump gold miner DRDGold, which recovered nearly 150 000 oz of gold from Gauteng’s mine dumps in the 12 months to end June, has entered the realm of nanotechnology in its relentless pursuit of every last particle of gold from the mountain of surface material at its disposal.
The JSE- and NYSE-listed company, which has just spent R300-million on new technology that wrings more gold out of waste tailings, is still seeing the better part of 0.16 g/t and 0.17 g/t slipping from its grasp and going back into the tailings dam.
The search is on now for even more advanced technology to do even better.
“Advances have been made in molecular recognition technology (MRT),” DRDGold CEO Niël Pretorius told Mining Weekly Online following the company’s presentation of 9% rise in operating profit to R679.3-million in the 12 months to June 30, which came with the declaration of a 180% higher dividend.
MRT is already being used to recover palladium, Mining Weekly Online can report.
“Maybe that sort of technology could ultimately be introduced into our environment as well,” Pretorius said.
DRDGold is already measuring its gold recoveries in the fourth decimal.
“We’re already in the nanotechnology space,” he said.
Up to now, the company has approached the recovery of gold from surface material as a metallurgical issue.
“I do think there might be some further solutions and we need to go out and find them,” he added.
The company, which is using a factory approach at its Ergo plant in Brakpan, is setting aside resources to crack the recovery code still further.
“A key near-term resolution is to attack that residue line,” Pretorius revealed.
Currently recovering 80% of the minus 25 micron gold, the company believes that it can do even better as it travels further down the nanotech road and studies the likes of MRT, which recovers cations and anions from waste streams.
The R300-million investment has bought the company a fully refurbished flotation circuit, which has the capacity to receive 1.8-million tons of material a month.
Four fine-grind mills, new to gold but common in platinum, have been built along with purpose-made carbon-in-leach and elution circuits.
It is hoped that the resulting concentrate with a gold content of 3.5 g/t will improve gold-extraction efficiency by between 16% and 20%.
But the 0.16 g/t and 0.17 g/t that remains unrecovered is seen as the big area of opportunity.
“We now want to focus on that,” Pretorius told Mining Weekly Online in the attached video interview.
“We think the technology is there. We just need to fit it to the volume flow.”
The integration of the Johannesburg-based Crown and East Rand-based Ergo retreatment operations has given DRDGold an 11-million-ounce resource.
It also has the pipeline network and fine-tuned infrastructure to process the large volumes of gold-bearing dump material that still lie in and around Johannesburg, which could extend its operational horizon for decades more.
At the end of it all, an environmental clean-up will have taken place and many hectares of urban property will become available for potential release onto the property market.
Risk is down, in the form of what is a veritable “gold factory”, rather than the deep, dark and dangerous mines of its past.
In the 12 months to June 30, DRDGold milled 8% more ore at 23 254 000 t and the recovered grade rose slightly, from 0.195 g/t to 0.196 g/t.
The higher capital expenditure (capex) and a 10% drop in the average fourth-quarter rand gold price received resulted in free cash flow generation falling 53% to R97.9-million, as outlined by DRDGold CFO Craig Barnes.
This cash plus the R165-million of debt raised leaves the company with cash and near-cash of R377.2-million.
The company declared a final dividend of 14c a share, contributing to a total distribution for the year of 28c, up 180% on the previous financial year.
Higher gold production and a 9% improvement in the average rand gold price received to R458 084/kg resulted in revenue increasing 18% to R2 076.5-million.
All-in sustaining unit costs, as defined by the World Gold Council (WGC), rose 10% to R365 569/kg.
Key contributors were the costs associated with the mining of additional sand resources at the Knights plant and above-inflation increases in the cost of labour, electricity and reagents.
The WGC-determined all-in sustaining-costs margin remained at 20%.
Capex was 13% higher at R361.5-million, owing mainly to continued development of the flotation/fine-grind circuit at the Ergo dump-retreatment plant in Brakpan.
Lower use of potable water and the suppression of dust emissions are being targeted.
The small Cason underground mine in Boksburg has been placed on care and maintenance.
Negotiations to conclude the sale of the company’s Zimbabwe assets are continuing.