A new solution to treat acid mine drainage (AMD), targeting the South African mining industry, was launched on July 5, in Johannesburg, as a viable and cost-effective solution to remove metals and sulphates from contaminated mine water.
The patented new technology from Finland-based company Global EcoProcess Services Oy (Epse) has been designed to transform the treatment of acid and industrial wastewater and solve the problem of metal pollution in mining and heavy industry. The end result is purified water and raw materials (in the form of metal precipitate), which is the spin-off of permanently converting the soluble metals contained in AMD into “harmless insoluble metals” that can be then used in production for several other processes.
According to Epse, the solution is a one-step process whereby contaminated water is first passed through a boric acid reactor, followed by a pH-modifying reactor and then a clarifier to produce insoluble precipitate and clean water. Processing in the boric acid reactor takes a few seconds, followed by a few minutes in the pH-modifier and a couple of hours in the clarifier for the heavier sediment to sink, thereby allowing the cleaned water to float to the surface.
Although a large volume of sulphates is removed through the process, Epse recommends processing the cleaned water through a sulphate-specific technology to further remove remaining sulphates, thereby producing potable water. Epse’s preferred method to remove the additional sulphates is a biological sulphate reduction solution. Other potential solutions include membrane technologies, ion-exchange or chemical precipitation.
The solution is set to be a game changer, according to Epse, which states that AMD in the South Africa mining industry is a serious concern, where the volume of wastewater from a single mine can be up to 300 000 m3 a day.
Solution Benefits
Key advantages of the Epse solution are low operational costs and low infrastructure investment costs. The solution can be retrofitted or integrated into existing AMD treatment solutions to further purify AMD, as well as used to process batches and continuous flows of AMD.
Epse CEO and partner Lasse Musakka says that, in countries like South Africa, where there is a shortage of clean potable water, Epse technology offers an innovative solution to bring about a sustainable and better future. “South Africa has been selected as the primary market for Epse technology for mine water treatment, after extensive market studies and our successful participation at the Mines and Money London conference in December 2015, and at the Mining Indaba conference, in Cape Town, in February 2016”.
He adds that the Epse technology has been tested and verified by independent accredited laboratories and industrial pilot tests. It has also been estimated to be able to achieve potential annual savings of up to €1-million, based on “conservative calculations for any currently operating mine with AMD problems”.
Epse board member, partner and head of international operations Felix Fondem says raw materials, water, air, biodiversity and aquatic and marine ecosystems are all under pressure from industrial processes and mining. He adds that lessening the environmental impact by reducing hazardous waste production and the ability to reuse waste as a resource and raw material enhance the social acceptability of mining.
Epse also claims that, unlike other currently available technologies, its solution removes metals completely, resulting in an inert and insoluble precipitate. The problem with soluble precipitates of metals is their classification as hazardous waste, which is required to be stored in controlled landfill deposits, thereby creating an increasing environmental risk globally, as well as high costs for mining and waste treatment companies.
Although primarily addressing the numerous metals in mining waste, Epse’s solution is also capable of substantially reducing concentrations of alkali and partially alkaline earth metals, which are a major concern where there is a need to recover water to a potable water quality level.
Founded in 2012, Epse has proved the success of its technology. The Mining Water Competence Network of Finland, led by the Geological Survey of Finland and funded by the European Regional Development Fund, chose Epse’s technology to address the AMD issue of Canadian incorporated mining company Belvedere Resources’ Hitura mine, in central Finland, as its priority research, development and innovation project. New permit regulations tightened requirements to the extent that AMD treatment using current methods would have become too expensive and challenging.