Multotec has partnered with Australian company CleanTeQ to introduce continuous counter-current ion exchange technology into the African mining industry for effluent treatment and metals recovery. “Clean TeQ’s Clean-iX® process is described as the future of hydrometallurgy as it progresses towards more sustainable minerals processing. “Hailed as the ‘Rolls Royce’ of ion exchange technology, Clean-iX provides customers with higher metal recoveries, lower capital and operational costs and reduced environmental impact,” Rolf Steinhaus, Director at Multotec Process Equipment says.

Clean-iX has a more compact footprint than conventional technologies as it at times eliminates a lot of pre-treatment processes and thus reduces the overall flowchart. “Mining is seen as an undesirable activity at times, often due to the negative side effects such as pollution or contamination. The goal with this technology is to be part of a more sustainable process, as it is environmentally friendly,” Steinhaus says. “Multotec would like to focus on smaller operations where we can containerise the technology, which makes for easier deployment and redeployment in Africa. Depending on the capacity, we can modularise containerised systems up to a 5 million litre a day capacity with the maximum containerised system capacity being 1 million litres per day. Beyond that we would need to consider skid-mounted or free standing systems. “The system is remotely controlled and completely automated, and therefore minimises labour and skill requirements on site which in turn reduces operating costs. Furthermore it utilises relatively cheap reagents to regenerate the resin, which also impacts positively on the bottom line,” Steinhaus adds.

While the principles of ion exchange are well understood, it has been commercially used in the water treatment and mining industries for more than 50 years. CleanTeQ’s innovation in this regard is related to its processes and equipment. “This is a fairly niche application that takes out dissolved metal ions or ionic complexes from a solution, whether water or a leachate. Continuous counter-current ion exchange technology, however, is certainly new to the African mining industry,” Steinhaus says. “It is a natural addition to Multotec’s product portfolio together with our already established solid-liquid separation equipment range.”

The potential for this technology is enormous given the vast number of applications for ion exchange and adsorption resins in several metal industries, and the ability to custom design the Clean-iX technology platform. The economical extraction of a range of metals, including heavy metals, platinum group metals, precious metals, base metals, rare earth elements, radioactive elements and selected Group I and II elements from a plant effluent or process stream is possible. The concept of continuous counter-current ion exchange is based on the fact that ‘continuous’ resin movement ensures it is always at the optimum point of equilibrium with the solution as opposed to batch processes, increasing overall system efficiency, while ‘counter-current’ resin and solution movement maximises the driving force of the reaction, reducing the comparative size of the process and allowing for a much higher extraction rate.

The process consists of a number of sub processes, each designed for a specific function, namely adsorption, fluidised wash, elution and wash. Depending on the application, there are three column types that can be used in order for the system to operate in the presence of solids ranging from 100 ppm to 40% by weight. These are the moving packed bed column, fluidised column and agitated bed column. Selection of the appropriate column type allows for optimal recovery of metals from leached pulps or from clarified solutions. Clean TeQ’s patented U column ensures concentration of the target metal in-situ, to produce an eluate of much higher concentration and purity than achievable with any other available elution technology.