The mining industry in Africa is becoming a more technology-focused sector with an emphasis on safety, longevity, efficiency and higher profitability, while respecting environmental targets and cleaning up waste product.
Technical advances are transforming the sector all the time, which is why a leading global manufacturer of gas process systems is urging mining operations in Africa to jettison conventional oxygen containers and replace them with the latest on-site generating technology.
Australia-based Oxair Gas Systems supplies Pressure Swing Adsorption (PSA) oxygen tonnage plants to mines in the Continent, bringing numerous advantages as well as eliminating the need for expensive and unreliable deliveries of liquid or cylinder oxygen.
Safety in gold mining is improved significantly through the use of oxygen generators. Mined rock is usually ground up and turned into a slurry by adding cyanide, oxygen and water before being fed through a carbon bed to extract the gold. Incorporating highly purified oxygen actually allows cyanide to work more efficiently and thus reduces the quantity of this poison required for the leaching process.
On-site oxygen generators provide a reliable stream of highly purified oxygen at the slurry stage, while having a constant supply of high purity oxygen on tap can also make the diversion of resources to clear empty oxygen cylinders a thing of the past.
Far more economical than adding calcium or hydrogen peroxide to increase slurry dissolved oxygen (DO) levels, a continuous flow of pure oxygen from a generator can enhance the gold cyanidation process. Typically, mines operating below 98.5% recovery can expect significant improvements.
When the concentration of DO is increased, the amount of cyanide required in the process can be decreased by as much as 25%. This has obvious implications for end of process waste removal too as the waste water will contain less cyanide and waste treatment costs can be reduced. In fact, a portion of the purified oxygen can also be routed through an ozone generator and injected into the waste stream. Here it works as an oxidising agent which helps to destroy any cyanide left in the waste water, thus creating an environmentally-friendly waste product that can more easily be disposed of.
A PSA tonnage plant takes oxygen directly from the air using on average only three kilowatts of electricity per 100 cubic feet of oxygen produced, and transforms it into highly purified oxygen by removing nitrogen entrainments (which are useless to the leaching process).
As with all high-quality engineering solutions, oxygen generators can be tailored exactly to suit an individual mine’s requirements. They can be designed for outdoor or covered facilities and as well as offering low energy consumption, usually come with a team of installation engineers who also offer on-site training to enable local employees to properly calibrate and easily maintain the system once it is operational.
On-site generators provide mines with a turn-key solution for getting a constant, reliable source of high-quality oxygen into their processes seven days a week. The typical period for getting a return on investment in a PSA oxygen tonnage plant is around three months – pretty quick!
It is clear that with responsible mining practices geared up for long-term sustainability, investments in quality equipment from companies such as Oxair, and the proactive nature of many national governments, that there is a real drive to see the mining industry evolve and mature in Africa.