Modern Mining July 2020

TREATMENT AND RECYCLING

externally sourced potable water usage through sewage water retreatment. Flagship projects Loots says Pan African Resources’ Barberton Tailings Retreatment Plant (BTRP) was the first of its flagships to be commissioned. “It is operating successfully and has a mine life of about nine years, or three years at the current rate of production.” He says the BTRP produces some 20 000 oz/yr at an all-in cost of around US$643/oz. The company’s most recent flagship, the new R1,7-billion Elikhulu plant situated at the Evander Mines complex, says Loots, demonstrates the com- pany’s expertise in terms of designing, building and commissioning tailings retreatment plants on time and within budget. “Elikhulu is also instrumental in ranking Pan African Resources among southern Africa’s lowest-cost gold producers,” he says. “The plant processes 1,2 Mt of historic tailings per month and is designed to produce about 65 000 oz/yr at an all-in cost of US$708/oz. The operation has a life of mine of 12 years.” He says the projects succeed “on various other levels” in terms of the long life of their operations, reducing the company’s rehabilitation liabilities, sus- taining the local economy and freeing up land to be rehabilitated for sustainable use. Pretorius says DRDGOLD’s two operations – Ergo, to the east of Johannesburg, and Far West Gold Recoveries (FWGR) near Carletonville – are both flagships with distinct characteristics: “Ergo is a large, well-established and mature higher- volume, lower-grade operation which provides the company with stability. FWGR, a lower-volume, higher-grade operation acquired from Sibanye- Stillwater two years ago, is smaller but has enormous growth potential.”

manually but they can be operated remotely today, making for improved safety.” He says the metallurgical processes at DRD are “no different” from those used in gold mining for decades: carbon-in-leach (CIL) and carbon-in-pulp (CIP). “In 2019, the DRDGOLD Brakpan plant switched from electrowinning (the final stage of gold recovery before smelting) to zinc precipitation, which is both cheaper and faster.” Digitisation has enabled 24/7 monitoring through- out the year of the entire production process, from reclamation to tailings deposition, allowing breakdowns and inefficiencies to be detected and remedied faster. “We regard research and development to improve gold extraction as an important focus. We have also been successful in developing and implementing more efficient, more environmentally- friendly and safe methods of tailings reclamation and deposition.” He says other areas “where strides have been made” are in the vegetation of tailings deposition facilities to contain dust, and in the reduction of

Tailings and sand retreatment are DRDGOLD’s core business.

Key takeaways  One of the major advantages of surface tailing and sand dump recovery the fact that it involves “considerably” less risk than underground mining  Given the sustained increase in the price of gold, both in US dollar and rand per kg, and the comparatively lower cost of tailings retreatment, the impact on profit margins will be extremely positive  While sand dumps are generally older and therefore higher in grade and more in demand, they are now scarcer, while slimes dumps, although lower in grade, are in relatively plentiful supply  Digitisation has enabled 24/7 monitoring throughout the year of the entire production process, from reclamation to tailings deposition, allowing breakdowns and inefficiencies to be detected and remedied faster

22  MODERN MINING  July 2020