Clean-iX® (Metals Recovery)
Acid Mine Drainage Treatment
Multotec ion exchange (IX) technologies can be used in acid mine drainage treatment. These proven technologies provide an effective chemical precipitation solution to scavenge toxic heavy metals and remove over 99.4% sulphate content of water, helping to prevent ground and surface water pollution from mines.
Unlike conventional batch-based ion exchange technologies, Multotec uses a continuous counter-current solution. This allows a continuous feed of acid mine water, optimised resin usage and management and reduced operator involvement.
Both CIF and Clean-iX were developed by Multotec’s Australian technology partner Clean TeQ, and offer the following benefits:
- Continuous counter-current process
- Very high resin efficiency and reduced resin inventory requirements
- Increased metal concentration and purity
- High solids handling capability & reduced number of process steps
- Maximum resin performance & selectivity with minimal reagent consumption
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Operates on solutions with up to 100 ppm solids, minimising pre-filtration requirements, requires up to 25% less resin than fixed bed systems & allows for fluctuations in feed grade.
CIF® (Process Water Treatment)
Simultaneous removal of suspended solids & dissolved ions, CIF® handles in-column precipitation, has high solids tolerance & offers optimised resin inventory.
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CIF® and Clean-iX® benefits:
Water treatment plants that treat AMD with CIF® and Clean-iX® technologies achieve a wide range of benefits that contribute to a more economical, reliable and environmentally sustainable solution:
CIF®
- High solids tolerance – the moving packed bed acts as a filter so it is not necessary for pre-treatment before using Clean-iX®
- Simultaneous removal of suspended solids and dissolved ions
- High water recovery (low brine volumes)
- Optimised resin inventory (smaller footprint)
- Handles in-column precipitation – gypsum, for example
- Recovery of potentially valuable by-products and/or trace metal recovery
- Low power consumption
Clean-iX®
- High product purity
- Higher product recovery
- The size of downstream processing is minimised – concentrated lower volume eluate
- Reduced need for pre-treatment – continuous resin-in-pulp and continuous resin-in-leach
- Selective metals recovery
- Operates on solutions with up to 100 ppm solids, minimising pre-filtration requirements
Frequently Asked Questions:
How acid mine drainage is treated?
Acid mine drainage causes harsh environmental pollution problems due to its high acidity, toxic metals and sulphate contents. Treating this environmentally challenging problem prevents toxic water from damaging the environment from its ground or surface water locations. In addition, it is possible to recover resources like ferric hydroxide, ferrite, rare earth metals, sulphur and sulphuric acid in the AMD treatment process.
Water treatment plants
The active treatment of acid mine drainage is swiftly moving to treating the actual acid mine water directly through water treatment plants using lime or other neutralising materials. This reduces the acidity, which causes metals to precipitate out of the contaminated water.
Multotec’s treatment for AMD requires a single CIF® system, which can extract acid from the water, producing neutral water for discharge. The increase in pH by the system causes several elements to precipitate, providing further water purification. This is possible due to the novel design of CIF®, allowing for in-column precipitation and solids handling.
If the resultant TDS of the product water is too high, the CIF® system can be replaced by a DeSALx® system. CIF®/DeSAlx® can also be used in conjunction with a precipitation step, which incorporates a brine recycle to allow for a zero liquid discharge (ZLD) process.
Other AMD treatment options
Passive treatment of acid mine drainage and other methods used to prevent and clean up acid mine drainage.
- Treating the contaminated water through artificial wetlands. This helps insulate contaminated material, and the microbial action produces oxygen-free conditions to help prevent further sulfuric acid formation.
- Reclaiming contaminated land. This is done by neutralising the acidity by adding lime or other alkaline materials, or by reducing surface water infiltration into underlying contaminated material. This can be done by adding uncontaminated top soil, planting vegetation, and modifying slopes.
- Relocating material. Relocating contaminated material to a site that facilitates monitoring and treatment of the soil.
- Filling abandoned mines. Filling mines that have been discontinued and abandoned with materials to prevent AMD formation. There are generally two methods: flooding the mine with water to remove the oxygen required to form AMD or filling the mines with alkaline material, which prevents the formation of acid water.
- Relocating and isolating mine waste. Mine waste can produce AMD if it reacts with water. By isolating the waste to prevent it interacting with groundwater prevents this. The waste is moved above the water table, treated and covered with a layer of impermeable material that keeps the surface water out.
- Using bactericides. Adding bactericides to kill bacteria that speeds up the formation of AMD, or by adding organic waste to provide an alternative energy source for the bacteria, which produces oxygen-free conditions and prevents the formation of sulfuric acid.
- Diverting water from the mine site. This prevents the water from running through AMD-forming materials, or disposing of mine waste underwater to prevent it being exposed to oxygen.
What causes acid mine drainage?
Acid drainage is a problem that is caused by the outflow of acidic water from a mining site, stemming primarily from oxidation of iron sulphide (pyrite or fool's gold), often found with valuable metals. It causes a major problem for many hard rock mines and coal mines.
What makes AMD harmful?
The presence of excessive and abnormal sulphuric leaching can have devastating environmental impacts by rapidly altering the pH of water sources and poison entire ecosystems. Severely affected systems can be completely inhospitable to aquatic life.
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Improve the performance and reliability of your acid mine drainage treatment with Multotec ion exchange technologies.