Kalahari Process™ unlocks full potential of iron ore tailings

The Kalahari Process recovers the -1 mm fine iron ore fraction from the ROM feed
Gravitas Minerals maximises the potential of iron by maximising its recovery from an orebody

The iron ore price surged in early December after customs data revealed that China’s iron ore imports rose 14.6% in November from a month earlier to hit their highest level since July 2020. It follows a slump in output from top producer China due to the government’s intention to cut production to clean up the environment, coupled with a slowdown in domestic demand for steel.

This is a ray of light in a year that saw the benchmark iron price surge by 62%, hitting a high of US$220 per metric ton in early 2021, only to slump to just over US$80 in November due to the Chinese curbs.

“The drive behind this downward trend is said to be a result of an oversupply of iron ore now that China has reduced steel outputs. However, this will cause a rise in steel demand that will be filled elsewhere, and where iron ore will be needed. With the decline in price, one must ask how this will impact iron ore producers?” questions Gravitas Minerals Director Tebogo Kale.

A lower selling price equates to lower revenues for iron ore producers, while production output remains the same. This means static expenditure and operating costs against shrinking profit margins, putting a strain on the economic viability of these operations.

“Maximising the potential of this mineral resource by maximising recovery from the orebody is one such solution,” says Kale. This can be achieved by exploiting the tolerances of fine material in the export product by recovering the – 1 mm fine iron ore fraction from the run-of-mine feed, rather than depositing it in tailings facilities.

Gravitas Minerals has developed the Optima Concentrator™ gravity separator to recover iron ore from a – 3 mm feed. It utilises hindered settling, fluidised bed and autogenous dense medium technology to separate iron ore from gangue based on density. With high throughput capacities of up to 40 t/h.m2, this is the ultimate low-footprint, water-only solution to fine iron ore recovery.

Therefore, the company has used the Optima Concentrator™ to develop its so-called Kalahari Process™, which produces an iron ore product with a minimum grade of 63.0% Fe from various iron ore feed sources. The process has seen great success to date by yielding recoveries of up to 80%. In addition, the process is ideally set up for the direct reuse of water by dry stacking of both the product and tailings streams.

An agglomeration stage added to the process can also produce fit-for-handling high-grade pellets. Another option would be to market the product as fines concentrate, a norm in the West African and Indian markets.

“By utilising the Kalahari Process™, iron ore producers can unlock the full potential of their mineral resource. In so doing, they can prolong the lifespan of their tailings’ facilities by up to 50%, reduce the disposal of iron ore tailings and the associated environmental impact, increase their revenues and ultimately boost profits,” concludes Kale.


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