Chemical Technology May 2015

Veolia stays on-site to reduce costs for Evander Gold Mine

Veolia Water Technologies South Africa has assumed the day-to-day chemical supply and services of the on-site water treatment for Evander Gold Mining in Mpumalanga. After a recent review report, four months into the three-year agreement, Veolia has already improved substantially on past practices and increased efficiency while reducing overall water treatment costs for the mine. Veolia embarked on this total water management agreement in November last year following a full site survey on Pan African Resources, Evander Gold Mining MET Plant as well as 7 and 8 shaft. This survey revealed that large parts of the water circuits were not being treated by any chemicals due to faulty dosing stations while other parts of the circuits were facing dangerous chemical spillages where dosing station pumps had broken. As a result, high- ly corrosive water and scale were flowing through the above and below ground water circuits, decreasing the mine’s cooling and ventilation efficiency while damaging its equipment. “We opted for a full operation and maintenance agreement with Evander Gold Mine, where we will manage the en- tire water treatment system. As part of the agreement, a Veolia specialist will remain on-site for the duration of the contract, providing 24/7 technical direction, support and consultancy,” says Carl van Heerden, Hydrex Industrial Manager, Veolia Water Technologies South Africa. As part of this agreement, Veolia sup- plied 12 new treatment solutions, including: new chemical dosing stations; flocculants, coagulants, anti-scalant and micro-biocide chemical treatment; a semi-automated du- plex flocculant plant; and coagulant plants to address the water treatment problems. Veolia also supplied its range of Hydrex™ chemicals at a variable fee after a weekly stock-take –meaning the mine will ultimate- ly only pay for chemicals it has used. Since the revised treatment plan was implemented, Junior Sales Consultant Pieter Jacobs, together with van Heerden, have managed and monitored the mine’s water treatment progress through weekly water analyses and reports. Results recently detailed in the four-month review of the programme show that the new treatment regime is not only out-performing com- pared to specification; it is also saving the mine money through a much more efficient operation. Due to the bad state of the circuit’s settlers at shaft 8, Veolia commenced treatment using gel blocks and added a

FOCUS ON WATER TREATMENT

Veolia installed spill-proof and accurate chemical dosing stations around the mine.

Veolia designed and installed 12 new treatment stations situated above ground and 1,8 km below ground that increased the mine's overall efficiency.

proved the overall iron and TDS concentra- tions as well as a visible reduction of algae. “The improvement of the water quality on the settlers benefits the entire water circuit. Overall TDS and iron concentrations are down, the circuits require fewer chemicals each month and the equipment gets closer to spec – ultimately running more efficiently and lowering overall maintenance costs,” comments van Heerden. “We also worked around the clock, 7 days-a-week to install new equipment in just 30 days – half the ex- pected time – and installation was relatively seamless considering we were adding and removing equipment so far below ground.” Owing to the early success of this agree- ment, Veolia is currently in negotiations with Evander Gold Mining to expand its outsourced agreements locally as well as within Pan African Resources’ other mines throughout southern Africa. For more information contact: Carl van Heerden, Hydrex Industrial man- ager, on tel: +27 11 974 8161, or email carl.vanheeerden@veoliawaterst.co.za

Hydrex™ 3936 coagulant. This dual treat- ment programme saw immediate positive results: the turbidity and Total Suspended Solids (TSS) levels were reduced by 45 % on settler 1 and 37 % on settler 2. Further- more, the duplex flocculant and coagulant plants have resulted in a further turbidity reduction of 27 % on settler 1 and 48 % on settler 2 allowing for proper dosing control while optimising the treatment programme. In addition, all old non-functional dosing stations at the fridge plant were replaced with new dosing stations, drastically improv- ing iron and Total Dissolved Solids (TDS) concentrations. At shaft 7, Veolia installed a new co- agulant dosing station that employs a custom-designed chemical treatment programme consisting of Hydrex™ 6611 and Hydrex™ 3936. This new treatment programme has resulted in a reduction of turbidity levels of 32 % and overall settler efficiency improvement from 90 % to 98 %. Two new dosing stations were also installed along with the condenser, main compressor cooling tower and spray pond. These stations utilised Hydrex™ 2204 and Hydrex™ 7761 chemicals, which again im-

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Chemical Technology • May 2015