KRUGERSDORP (miningweekly.com) – A process has been developed that yields handsome profits by converting acid mine water into valuable fertiliser materials.
The process removes all of the total dissolved solids and converts them into saleable products.
“The whole treatment cost is zero,” Trailblazer Technologies director John Bewsey told Creamer Media’s Mining Weekly Online while putting the company’s pilot plant through its paces, in Krugersdorp. (Also watch attached Creamer Media video). Treating 15 megalitres of acid mine drainage (AMD) a day yields 49 000 t of high-value potassium nitrate and 24 000 t of ammonium sulphate. Potassium nitrate used in fertiliser is retailing for R15 000/t and Trailblazer will market it at R11 500/t. “We’re left with useable water at no cost and the whole process turns in a very handsome profit,” said Bewsey, who envisages funders being attracted by the scheme’s 30% return on investment. Trailblazer’s model is to build plants in partnership with funders and enter into contracts with mining companies to treat their AMD. It envisages funders making good profits, mines having the AMD problem solved and farmers being shielded from sodium damage. “It’s a complete win-win,” Bewsey commented. It would also save taxpayers the R12-billion that Water Minister Nomvula Mokonyane announced last week would be needed to turn AMD into safe water for commercial use as either industrial or potable water. The Minister chose the old south-west vertical shaft area of the dormant East Rand Proprietary Mines for the launch of the process to remove the sulphates. Bewsey described the department’s wasting of sulphate to form gypsum as “not the brightest of ideas”. Instead, Trailblazer would use an alkali like soda ash to produce potassium nitrate for highly profitable sale into agriculture.
ROBBIE ROBINSON Bewsey explained that Trailblazer Technologies had added on to an original idea put forward in 1996 by the late Dr RE (Robbie) Robinson, who died in December at the age of 86. Robinson’s zero-cost plan for AMD was drawn up 20 years ago for the now stricken Grootvlei gold mine, on the East Rand. It involved moving away from the process of adding large quantities of lime into the AMD, precipitating it and allowing the overflow to go into the local Blesbokspruit. Instead, the visionary chemical engineer with distinguished involvement in minerals beneficiation spanning more than 60 years and a passion for linking mining and agriculture, formed an association with a company specialising in the ion exchange method and engaged previously disadvantaged technikon students to develop a new process that made use of the ion-exchange resin that Trailblazer Technologies is now using at its Krugersdorp plant. In the Grootvlei case, the resin removed the ferric oxide and the acid and was easily regenerated by eluting it with ammonia and producing ammonium sulphate for fertiliser. The red ferric oxide was very saleable along with nigh nuclear-grade uranium as well as cobalt, copper and nickel oxides.
Moreover, the virtually distilled water was earmarked for agricultural irrigation. Taking all this into account, the Grootvlei gold mine would have been put into a position to treat its AMD at zero cost, with Robinson’s innovative new process opening up agricultural pursuits for the people of the nearby informal settlement. However, the Department of Water Affairs broke Robinson’s heart when it opted instead for a far more expensive R10-million alternative that fell flat on its face, had to be discontinued and probably contributed to Grootvlei’s demise, along with the subsequent ignominious Aurora liquidation debacle. Now the department is again looking to a far more expensive long-term solution, which will be a major cost centre rather than the lucrative profit centre it could be through the sale of recovered fertiliser chemicals.