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Could this be key to solving SA’s acid mine drainage problem?

Written by  Sungula Nkabinde - MineWeb Wednesday, 06 July 2016 19:27
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  A new Finnish technology could revolutionise treatment of acid mine water and industrial waste. 

 

JOHANNESBURG – Finnish company Global EcoProcess Services (ESPE) has developed and patented a process that it claims will revolutionise the treatment of acid mine drainage (AMD) and industrial waste. AMD is highly acidic water, usually containing high concentrations of metals, sulphides, and salts as a consequence of mining activity.

By adding boric acid to the water treatment process, they discovered a way of separating toxic metals through a precipitation process, producing cleaner water and insoluble metals (or ‘precipitate’) that can be used as raw materials for other purposes.

On Tuesday, representatives from the company gave a presentation to government officials, academics and interested businessmen, on how the technology works and, claiming their method is cheaper, more efficient and simpler than any other water treatment process, saying it required minimal capital outlay and could be integrated into existing waste treatment solutions.

“We have been working on this innovation since 2012,” said CEO Lasse Musakke, stating that current methods cannot extract several metals at the same time, and that the precipitates extracted are soluble, meaning they would still be regarded as hazardous waste. With the EPSE process, many metals are separated in one step and the precipitate can be stored in any landfill, without the high storage costs and environmental risks that come with hazardous waste. 

“Precipitate produced with current technologies is still hazardous, and the end storage costs are €500 to €1000 (R8 171 to R16 343) per tonne, whereas the end storage costs for the environmentally harmless EPSE precipitate are €50 to €80 (R817 to R1 307) per tonne,” Felix Fondem, EPSE director of international operations.

“All of the elements that we are applying in this technology are existing,” said EPSE partner Vesa Kainulainen, “But our innovation is how to apply that in the process. That was unknown, especially with regard to what boric acid can do in a multi-metal solution.”

Still not safe for drinking

The water that is cleaned through this process, however, is not safe drinking water. Although it removes almost all metal, it still contains around 700mg-1400mg of sulphate per litre. In South Africa the maximum limit is 400mg per litre.

Said Kainulainen: “Our method is ideal for pre-treating the multi-metal solution, with some amount of sulphate remaining and then to use another process, which could be biological treatment of reverse osmosis to purify it. Personally I would prefer reverse osmosis because then you have a product that can be sold at the end of that process, which is sulphuric acid. Through reverse osmosis you only have potable water at the end of the process.”

Antti Eriksson CEO of Finnish waste treatment company Kierto said the EPSE process reduced waste treatment costs by as much 50%. EPSE has identified South Africa as the primary market for their technology, stating that an investment of around €48 billion (R784 billion) is needed over the next 10 years to modernise SA’s water and waste water infrastructure, so a cost effective recycling solution is essential.

One of the reasons South Africa has been identified as a primary market is that the volume of waste water from a single mine can be as much as up to 300 000m³ per day.

Kierto will be their partner for rolling it out to waste treatment plants and mining companies, which will have to get a license to use their method. But there are still some tests that need to be done to prove the innovation is suitable in South Africa, where the environment is very different and much hotter than Finland.

“Although the chemistry of AMD generation is straightforward, the final product is a function of the geology of the mining region, presence of micro-organisms, temperature and also of the availability of water and oxygen. These factors are highly variable from one region to another, and, for this reason, the prediction, prevention, containment and treatment of AMD must be considered carefully and with great specificity.” – Council for Scientific and Industrial Research briefing note (2009).

There have been many before this

Dr Kevin Harding from the Industrial and Mining Water Research Unit at University of the Witwatersrand said the claims that EPSE made were feasible, but still needed to be tested.

Mariette Liefferink, CEO of the Federation for a Sustainable Environment, echoes this, saying EPSE is not the first innovation into acid mine drainage. Because government has only considered the reverse osmosis process and the iron exchange processes of the desalination process, they have been facilitating engagements between innovators and the mining companies.

“Over the years, there have been hundreds of companies with new solutions to the acid mine drainage problem. Some of them were successful on a small scale. Most of them were not successful,” says Liefferink.

“It all depends on the cost. Many of these technologies are successful for removing the metals and to remove the sulphate. But the problem is the economical viability. Currently, in the Western Basin, Sibanye Gold carries a third of the cost and the remaining two thirds is carried by government and, by extension, the taxpayer.”

She says AMD is the most costly socio-economic and environmental impact of mining and that, if it is not contained, there will be more water deficits and restrictions, and economic activity in six of the country’s provinces may be curtailed.

 

 

 

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