Mining solutions com- pany Fraser Alexander and water treatment company Mine Water Treat- ment Technologies (Miwatek) last week launched their acid mine drainage (AMD) treat-ment solution in Randfontein, west of Johannesburg.

Unlike traditional AMD treatment solutions, which generate high volumes of sludge and brine, the Miwatek technology offers a total solution and allows for the production of reusable waste, which cofounder Pieter Jansen says renders it more cost effective than other technologies.

It is also the only water-treatment solution that offers the benefit of about 50% less solids (waste), compared with the industry average, he added.

The solution incorporates sophisticated modelling, based on the chemical analysis of the specific water to be treated, the locally developed Abrimix Mixer technology and reverse osmosis (RO) membranes from US-based stakeholder Jalema Technologies, which enable optimal plant design and, there- fore, an optimal water treat-ment solution.

Typically, there are two or three stages of RO recovery, with chemical pretreatment stages before each RO stage.

The Miwatek solution can also integrate a type of evapor-ation and crystallisation tech-nology into an overall process proposal that can deliver zero liquid discharge, with all the crystal products in the form of industrial-quality reagents rather than a mixed crystal mass that has to be disposed of.

Chemical and waste expert and consultant Dr Richard Paxton points out that, as the technology offers the benefit of analysis-based design, it can be adjusted according to the requirements of each client to ensure an optimum AMD treatment solution.

Fraser Alexander water treatment division head Ken Bouch says the firm took the decision last year to buy a stake in Miwatek and com-mercialise the technology, which it sees as complementing its existing services.

“The process is flexible, innovative, comprehensive and solves one of the main challenges of AMD treatment, which is the large volume of hazardous waste, while allowing for high recovery of discharge-compliant water,” he says.

The technology also offers the benefit of treating variable feed-water qualities and sig-nificantly reducing life-cycle costs, as the long-term liabilities associated with the disposal of the residues will be significantly lower.

Bouch further states that the Miwatek plants will not be sold to clients, but that they will be designed and built by Miwatek, but owned and operated by Fraser Alexander during and beyond the life of the mine.

“Effectively, clients would only pay for clean water, which means no process risk for the client,” he notes, adding that the Miwatek role-players also intend to keep the intellectual property behind the technology in-house and will, therefore, only offer an on-site water treatment service, rather than selling the plants.

Bouch says Miwatek partner Steval Engineering constructed a pilot plant at gold miner Gold One’s Number 8 shaft last year, which proved to be successful, adding that this has served as motivation to launch the technology. He says mining firms have already expressed significant interest in the technology and that a two-week-long promotional period is currently under way to demonstrate the solution to potential clients.

The pilot plant, which boasts a capacity of 12 m3/h and which is only a two-stage RO plant, is capable of achieving a minimum water recovery rate of 98%.

Further, Jansen says the Miwatek solution also offers faster calcium control and membrane protection. “Mixing reagents to fix the gypsum problem used to take three to four hours but, with the new technology, this is reduced to minutes, which results in a significantly reduced plant footprint.”

“This process has taken us a major step forward,” Miwatek cofounder and Jalema Tech-nologies owner John Lombardi tells Mining Weekly.

He states that mining firms will appreciate the convenience offered by the Miwatek solution. “No mine manager is trained in water treatment at university, so they are happy to sign a cheque and let somebody else do it,” Lombardi notes.

Meanwhile, Miwatek is also in the process of piloting a solution that creates a relatively diluted and low-quality caustic soda solution from the final brine, which should be sufficient to replace much of the hydroxide input that is needed for all the pretreatment reactors.

This process addition, where feasible, will enable overall brine production to be at least halved and, in some instances, almost eliminated, while the third pretreatment and RO stage will be avoided and high-purity gypsum will be created.