Successful Application of ElectroClear Technology to Treat Acid Mine Drainage
Management of acid mine drainage (AMD) and other mine-influenced water has traditionally represented a significant challenge to mining companies around the world.
Clean&Recover has successfully trialled its ElectroClear technology to treat and clean AMD supplied from mine sites including:
- Mt Morgan
- Texas (near Stanthorpe)
- Mungari
- Mt Carlton
- Rio Tinto US site
- Maurliden (Sweden)
Participating mines are interested in exploring what they can do with mine-influenced water. They want to know if they can extract the metals dissolved in the water, and whether there is anything better than traditional lime or caustic soda treatment.
ElectroClear offers mining and industry a demonstrated alternative solution to help meet these strategic and operational goals.
The Challenge of Acid Mine Drainage and Other Mine-Influenced Water
Mines face significant challenges managing and treating AMD, including removing contaminants at levels far in excess of safe standards for discharge according to world water quality guidelines.
Many mining companies are dealing with a number of closed or soon-to-be closed mines around the world with significant flows of mine-influenced water.
These mines are looking for short-term solutions to remove contaminants. But current methods of treatment come with multiple costs and operating issues without any value-adding options. The current process of active treatment using lime or caustic soda presents the following challenges:
- The sludges trap significant water. For example, an analysis of a lime treatment plant at Mt Morgan found that it only generates 52% water return from its operations, with the remainder of the water trapped in the sludge or lost as part of the process.
- These methods involve the addition of large volumes of lime or caustic soda, which can pose environmental risks if added at rates in excess of requirements.
- These forms of treatment lock the metals present in the AMD into the sludge, making them unrecoverable.
- The lime or caustic soda are safety risks during transport, storage, and handling.
- Adding the lime or caustic soda to AMD has lots of challenges such as the poor solubility of lime, armouring, and poor purity.
- Transporting lime or caustic soda to remote mine sites is costly.
Moreover, mining companies are coming to see that acid mine drainage represents not just a waste and a cost. It contains potentially valuable elements that can be used to offset the costs of rehabilitating and treating the water to return it to a useable state.
Why Participant Mines Chose ElectroClear
Participants have conducted workshop-scale trials of the ElectroClear technology to find a better way of treating AMD and other mine-influenced water.
They have discovered that the ElectroClear technology can clean AMD at a lower cost than existing lime-based treatments, while being more reliable, and avoiding the safety risks of transporting, storing, and handling dangerous chemicals.
Participant mines are investigating the benefits for their sites, including the value that can be recovered from the material.
Rio Tinto, for example, has noted that, ‘We are very interested in Clean&Recover’s technology’s ability to selectively recover metals from acid mine drainage.’
How Workshop-Scale Trials were Conducted
Following extensive lab-scale testing of electrodialysis as a treatment for AMD, Clean&Recover began working with a number of mines globally to conduct workshop-scale trials of the technology.
Trials involved the treatment of AMD supplied by mines in Australia and globally to investigate the benefits the technology offers.
Participant mines provided sample AMD for treatment. Clean&Recover treated the water and provided results for energy use, treatment rates, and output water quality. Clean&Recover can demonstrate a pathway for precipitating and collecting metals from the water for commercialisation.
Energy Use
Water Cleaning
Resources Capture
The Results
ElectroClear demonstrated a number of key benefits for participant mines, including with regards to energy use, capital and running costs, improved management of AMD and access to valuable metal and water resources which can be reused.
Energy use results
Energy use varies according to the type of acid mine drainage being processed, but ElectroClear was able to clean AMD for an energy use as low as 0.7 to 2 kWh/1000L.
This opens the possibility of using the technology not only to treat AMD but to raise the pH of water for minerals processing.
Water cleaning results
ElectroClear has demonstrated that it can remove metals and other elements from AMD.
Aluminium, Arsenic, Cadmium, Chromium, Cobalt, Copper, Iron, Lead, Manganese, Magnesium, Molybdenum, Nickel, Vanadium, and Zinc to levels of 99% or more, and Antimony to 90% or more.
Sulphate has been removed to 250ppm.
The output water is acceptable for discharge to the environment. Alternatively, the water can be returned for use on site and the mine can request that the water be returned at the pH that the mine wants for minerals processing purposes.
Resources capture
ElectroClear has demonstrated that it can capture these metals as a precipitate. This precipitate settles quickly, is very low in water and very high in metal content, making it processable for value for the high value metals in the AMD. During processing, ElectroClear can control the pH to selectively precipitate given metals at a given pH, enabling separation of metals that precipitate at low pHs from metals that precipitate at high pHs.
As part of the process, ElectroClear removes sulphates from the AMD and concentrates them as sulphuric acid.
The ElectroClear process generates hydrogen and oxygen, which can be captured for value.
Why choose ElectroClear
ElectroClear is a proprietary technology that offers significant benefits over traditional AMD treatment and management options.
It has demonstrable benefits related to cost and energy savings, improved resource utilisation and environmental discharge.
To discuss the application of this proven technology at your site, please contact Clean&Recover:
Luke Berry
CEO
Ph +61 417 077 342
luke.berry@cleanandrecover.com.au
www.cleanandrecover.com.au