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In depth: Reducing rare earths extraction complexities

Carien van der Walt, environment process engineer at Multotec Process Equipment, training operators on the functionality of the Clean-iX pilot plant’s automation system

Rare earths may be included in most electronic devices such as mobile phones and televisions, but the hydrometallurgical recovery process can be onerous and very complex.

In spite of the fact that rare earths are abundantly available, they are often found in such small concentrations that it makes the mining and beneficiation process uneconomical.

Since global demand for rare earths production continues to increase, it is important to find ways of extracting the usable elements in a simple and cost effective manner. “Interestingly, two of the world’s largest primary rare earths deposits are in Africa so it is appropriate that a South African company has partnered with Australian company Clean TeQ, to offer the local market a viable rare earth element (REE) beneficiation process,” says Carien van der Walt, process engineer for environmental products at Multotec Process Equipment.

Current REE processes are generally characterised by excessive levels of thorium and uranium remaining in the product, with the resultant radioactive waste that is produced being hazardous to the environment.

Van der Walt maintains that Clean-iX technology makes the processing a little less complex and significantly decreases the impact on the environment. Clean-iX offers two options for customers. In the first instance, rare earths can be recovered with far less thorium and uranium extracted, reducing the amount of impurities sent to precipitation along with the final product.

The second solution entails selective recovery of the uranium and thorium in two separate processes, resulting in the thorium, uranium and rare earths being produced as three separate streams. The thorium and uranium can also be selectively extracted and recovered using Clean-iX prior to the REE extraction step. “Clean-iX produces a concentrated product of rare earths in solution or solids that can be sold and toll refined. This makes it a really cost effective option for small scale operators who do not have the capabilities or capacities to process rare earths to the final precipitated product,” says Van der Walt.

She explains that generally the resin that has been loaded with rare earths in the Clean-iX process is regenerated with hydrochloric acid. “This is important as the solution produced is bulk rare earths in a chloride matrix, which is ideal for further processing using conventional rare earths beneficiation processes.”

As an example of the added value provided by Clean-iX, the technology was used in Asia to recover rare earths from iron ore slag producing this rare earths solution. In other applications in Australia and Japan, the technology is being used to recover scandium.

Depending on the ore type and composition, the Clean-iX process for REE processing can replace the leaching circuit and the second step of two-stage precipitation in conventional REE recovery circuits with a continuous resin-in-leach ion exchange process. Using the continuous resin-in-leach (cRIL) process will result in….

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