The use of Gaustec wet high-intensity magnetic separation (WHIMS) technology in the beneficiation of minerals has the potential to be used to great effect in South Africa, mining solutions provider Blu Sky Mining director Graham Joyce tells Mining Weekly.

The technology has a large footprint in the Brazilian iron-ore industry and is well-known in other parts of the world, he points out.

Blu Sky completed a study for the processing plant of an iron-ore deposit, in Uruguay, in 2019, and the Gaustec technology was identified as an effective upgrade technology based on its Brazilian iron-ore track record, he says.

Joyce says the Gaustec WHIMS machines proved to be reliable, easy to operate and have high availability and separation efficiencies.

This is owing to its innovative matrix design, which results in higher throughput, improved selectivity during separation and a significantly reduced risk of matrix blocking, he notes.

The Gaustec WHIMS machines can process material with a particle size distribution (PSD) of -3 mm to 0 mm.

This is achieved by adjusting the matrix gap to optimise the gap for the feed PSD. Matrix gaps range from 0.5 mm to 5 mm and solids throughputs range from 30 t/h to 1 400 t/h per machine.

Joyce acclaims that Gaustec is a step ahead in the beneficiation of the full PSD, with affordable operational expenditure and capital expenditure solutions for all applications.

Joyce indicates that testwork has indicated recoveries of over 60% of gold and uranium oxide (U₃O₈) on Witwatersrand slimes dams with 10% mass yields, which he posits could be of great interest to gold producers.

Joyce informs that the high-throughput units, with a small footprint and ease of operation, are suitable for bulk processing such as iron-ore fines, chromite, manganese and/or the reclamation of slimes dams.

He adds that Gaustec technology is well suited to treat most minerals with magnetic and paramagnetic properties either as an upgrade stage or to remove the paramagnetics as an impurity.

In South Africa, this technology is viable for certain producers of chrome, manganese, iron-ore, nickel, lithium, copper, platinum group metals (PGMs), ilmenite, tungsten, zinc, tantalum, niobium and molybdenum.

Joyce says the technology is easy to operate, robust and has flexible operating parameters to cater for a wide range of conditions like ore feed grades, feed particle size distributions and varying orebodies.

He enthuses that it offers many benefits, including higher feed slurry densities; less wash water applied in middlings and magnetics fraction removal; adjustment of matrix gaps through the addition or removal of spacers; a low capital expenditure per ton feed; low operating expenditure; high availability; no desliming required; high efficiency; a small footprint; and improved separation efficiency in fine and ultrafine minerals.

Blu Sky, as the sole agent for Gaustec in sub-Saharan Africa, began running tests on South African ores to build up a database of information relevant to the local mining industry after having visited mine sites in Brazil where the technology was being used.

Joyce informs that, as sufficient data is now available, the next phase is to make these results known to selected clients.

Concurrently, Blu Sky is involved in projects using WHIMS technology, and Joyce says the results from this are very promising and these projects are moving quickly towards implementation.

He notes that the response from project owners is very positive and that extended testwork programmes are under way.

Moreover, the company also has a pilot plant in Gauteng, which has been operational since March 2020.

From this, Joyce highlights that “excellent” results have been achieved in the removal of chrome in PGMs flotation feed; the recovery of chrome from fresh feed and from flotation and spiral tailings; the upgrade of iron-ore to final product; and the recovery of lithium.

Joyce says the plant is well located to run test campaigns for mining operations within the country.

Blu Sky’s main focus is on getting the first installed unit operational in the country.

“That can be used as a springboard to prove all the performance capabilities of an operational unit. We also encourage potential clients to accompany us to visit operations in Brazil,” he notes.

He says the main challenge in introducing this technology in the country is the economic environment, with mining houses cautious of executing new projects.