While West Africa is considered to be a “premium” gold mining region, owing to it achieving a significant return on investment for its mining operations, the industry lags in terms of beneficiation, most notably for gold, says minerals processing equipment manufacturer Multotec West Africa GM Godwin Dzwairo.

He explains that Multotec has, therefore, introduced its SX4 spiral concentrator at various mines across Ghana for carbon degritting applications to remove impurities, thereby enhancing efficiency in the downstream, or loaded carbon elution process, which allows for efficient gold recovery from the carbon after which it is processed, refined and sold.

Carbon degritting is the process of cleaning used carbon in minerals processing by separating the carbon from the grit based on density and reintroducing the cleaned carbon into the mining operation.

As a result, operations introduce cleaner carbon that will not compromise the recovery of gold while also improving metallurgical accounting by allowing for a more accurate estimate of expected gold output.

“By cleaning the grit, we remove the excess weight that can otherwise falsify the expected gold output,” notes Dzwairo.

Moreover, by removing waste, mines can reduce the amount of chemicals used in the elution process. The carbon degritting solution does not have moving parts, with low energy consumption, no chemical requirements and no heating required during operations.

The spiral also does not produce carbon emissions while being a cost-effective solution.

The SX4 spiral can also be applied to coal beneficiation for the production of thermal coal.

Therefore, Multotec provides an array of other spiral concentrators to improve recoveries from various commodities such as chromite ore, iron-ore and copper.

“Spiral concentrators are applicable to various commodities because the concept remains the same – separating your valuable material from your impurities or your discard material,” says Multotec process engineer Refentse Molehe.

The SX4 spiral does not require operators to have a specialised set of skills or undergo extensive training to use or implement it. The carbon degritting solution can be customised to support the clients’ requirements which can be done by retrofitting it on an existing plant, she adds.

Alternatively, mines can install a test rig solution which includes the entire degritting structure, the pump and sump, the spiral and feed distribution box.

Regardless of how much carbon with grit impurities mining companies generate, the installation of the carbon degritting spiral will enable improvements and a cleaner final product, with Molehe stating that the SX4 spiral can handle carbon with grit particles of up to 2 mm.

The most recent installation of an SX4 spiral was for a gold mine in Ghana.

The project involved retrofitting the carbon degritting spiral into an existing plant and the successful project was achieved through the support of contracting design engineers in acquiring the measurements and examination of existing structures to ensure that the structures could support the spiral.

The successful implementation of the SX4 spiral for the carbon degritting application has encouraged Multotec to penetrate other markets with existing mineral processing technologies, with Dzwairo noting that the company is continuously innovating its existing technologies for various industries.

For example, while the SX4 spiral was initially designed for coal beneficiation, through Multotec’s continuous research and development initiatives they were able to uncover other potential applications of that spiral such as carbon degritting.

Additionally, Multotec aims to expand its footprint in the region of Guinea by the end of the second quarter to mitigate regional constraints by having teams closer to West African clients.

“We aim to be the lead minerals processing equipment supplier and service provider to the West African mining industry,” Dzwairo concludes.