Johannesburg-based incineration technology company Saubatech supplied a gold recovery incinerator to a gold mine in Tanzania last month, says Saubatech director Andreas Thieme.

The mine is operated by a gold major and the recovery system is being commissioned by Saubatech.

“During the elution process, activated carbon that is deemed too fine for reuse is removed. The system provides a reliable and cost-effective method to recover gold from fine carbon,” Thieme explains. He notes that the fine carbon residue contains about 50 g/t of gold to 200 g/t of gold, but it could sometimes be as much as 800 g/t of gold.

“This, of course, helps the gold mines tremendously to get more gold out and to make them more profitable.” He mentions that the gold price has become quite weak in the past couple of years and that gold mines have tried to find other ways of recouping gold from their existing operations.

The system uses a thermal process that burns off the carbon and captures the gold residue in the resultant fly ash using highly efficient ceramic filters. The entire process is fully automated to increase productivity of the plant. The system operates continuously, burning 60 kg/h to 90 kg/h of activated carbon, which translates into processing 25 t a month to 30 t a month of activated carbon. It also has a recovery rate of 93% to 95%.

Thieme points out that the initial cost of the system is quite high, but the return on investment is usually between eight and twelve months, depending on the gold concentration in the carbon particles and daily operating hours.

Further, the company offers a lease-to-purchase agreement, whereby clients can pay a monthly rental fee while Saubatech operates and maintains the system. When the investment has been paid off, the system belongs to the client, who can choose to continue renting the system if it is preferred that Saubatech continue to operate and maintain it. The company also offers the maintenance and operation services to clients that purchase the system.

The company is considering the offering of such agreements for its general incinerators.

Thieme advances that the company continuously upgrades its incineration processes to make it more efficient and easier to operate. In the past year, the company has containerised the control unit of the gold recovery system so that the control panels and programmable logic controls are in one control room.

“Owing to the remoteness of the mines, and the heat and dust that are usually associated with them, we have also incorporated ventilation, air conditioning and dust monitors into the containers,” he adds. Saubatech can also custom-make the system to client requirements.

Moreover, owing to combustion taking place at a high temperature, and ceramic filters removing particulate matter, the process achieves results without compromising the environment.

Thieme notes that many gold mines are opening in West Africa and that this presents an opportunity for Saubatech. There are gold recovery systems operating in South Africa, Tanzania, Ghana, Mali and the US and he notes that the company would like to expand into other African countries.

The company also has many general incine- rators for waste disposal operating at mines throughout Africa. Saubatech’s incinerators can comply with European Union and US emission standards if filtration is used.

The company aims to continue offering a good service and product, as well as regular upgrades, to make its incinerators more efficient, Thieme concludes.