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PLATINUM
 
New process opens way for full-spectrum platinum beneficiation
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5th April 2012
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JOHANNESBURG (miningweekly.com) – The Kell Process, which slashes electricity consumption by eliminating the power-guzzling smelting step in the processing of platinum-group metals (PGMs), also opens the way for full-spectrum platinum beneficiation, including the facilitation of fuel cell and autocatalytic converter manufacture.

Liddell Associates' Keith Liddell tells Mining Weekly Online in a video interview (see attached) that Kell’s hydrometallurgical process leaches the PGMs out of the concentrate.

To add Kell to a 250 000 oz/y PGMs operation costs $65-million.

Kell removes the need to melt the concentrate at 1 600 oC, which Liddell regards as “the sledgehammer to crack the nut”.

Kell recovers 99%-plus of the platinum and 98% of the remaining PGMs, as well as the base metals.

Liddell patented Kell – the letters that make up his initials – as a smelting alternative in 1999 and has continued to fine-tune it ever since.

“It’s a completely different processing route,” says Liddell, who first conceptualised it when, as platinum junior in the 1990s, he was producing insufficient concentrate to justify investing in a smelter.

Kell consumes a mere 14% of the electricity that smelting consumes, 140 kWh of electricity for every ton of concentrate processed compared with 1 000 kWh of electricity for every ton of concentrate smelted.

Kell requires no milling and emits only 440 kg of carbon dioxide (CO2) a ton of concentrate treated compared with 1 400 kg of CO2/t for the estimated two-million tons of concentrate treated in South Africa a year.

Kell also copes well with the chromite in upper group two (UG2) reef, which smelting finds problematic.

Recovery is lost in the flotation process to enable smelters to cope with the chromite in the UG2 concentrate.

Kell takes away the grade constraint the smelters have, which results in 5% more platinum being recovered in the flotation plant.

Kell makes use of standard pieces of off-the-shelf or out-of-the-catalogue equipment and because of its modularity, there is no need to sink large sums of capital into one big smelter ahead of time.

Moreover, the third stage of Kell is the first stage of the PGM-refining process, in which the PGMs are brought into solution.

Kell has the PGMs in solution and more parts can be added on depending on how much capital is being spent to facilitate the manufacture of items like autocatalysts or fuel cells.

“That’s the value of hydrometallurgy having everything in solution in a form that allows decisions on what products should be made from it. We’re talking about a possible Silicon Valley for platinum,” Liddell tells Mining Weekly Online.

“When I start to think about the possibilities I get fired down the process stream and I’ve got to bring myself back up to the frontend where the focus needs to be at the moment,” he adds.

The intellectual property and patent rights are in a Mauritius-registered company of four main shareholders, one of whom is the chemical brains behind the whole thing, Dr Mike Adams, who has a double PhD in chemistry and who worked with Liddell in the 1980s at South Africa’s State-owned minerals research organisation, Mintek.

After graduating from Birmingham University in 1981 with a degree in minerals engineering, Liddell joined Mintek and two weeks later found himself optimising flotation recovery at Western Platinum’s first UG2 concentrator in North West.

He carried on working primarily in the platinum sphere during his time at Mintek, eventually helping to design and built the Kroondal platinum mine in 1997.

It was then that he began conceptualising and then accelerating the development of Kell, which is ideal for juniors, who are paid only 80% of the value of concentrate by toll smelters.

Juniors who choose to make their own metal on site benefit from lower royalties and beneficiation credits and reduce the cash lockup of selling their concentrate to majors and waiting four months to be paid.

Kell appears to be robust for different minerallurgies as the many South African UG2, Merensky and Platreef concentrates and North American concentrates put to the test have all given a 99% platinum recovery.

Bateman has concluded that there are no fatal flaws in the fundamental chemistry and engineering, engineers have done independent scoping for capital and operating cost determination and the latest peer review will conclude at the end of April.

A definitive feasibility study will follow a large pilot test, which is due to take place in laboratories in April/May.

“If all of that comes to fruition in the next six months, we could be moving to construction towards the end of the year on a 12-month construction phase,” he says.

The main reason that Kell consumes only one-fifth of smelting’s power requirement is that the waste moves through the process without being changed at all and without consuming any electricity.

FUEL CELLS

Anglo American CEO Cynthia Carroll told the United Nations climate change convention’s seventeenth Conference of the Parties in Durban last year that the window of opportunity was “wide open” for South Africa to create “hundreds of thousands of new jobs” and simultaneously obtain a source of clean “zero-emission electricity” by developing fuel cells in this country.

“With platinum at its heart, a fuel-cell industry would support South Africa’s drive for jobs,” Carroll added.

Department of Trade and Industry (DTI) director-general Lionel October told Mining Weekly Online in January that a DTI team was working with participants to determine the economic viability of establishing a central platinum hub with satellites that allow for locational flexibility.

South Africa’s Department of Mineral Resources has identified platinum as a candidate for value-chain development, backing up disparate research work for decades by the likes of platinum promoter Johnson Matthey.

A platinum-using catalytic converter company, which currently does the bulk of its manufacture in Japan, says that a 10% price preference as part of the beneficiation strategy will be sufficient to attract it to set up a manufacturing facility in South Africa.

Science and Technology Minister Naledi Pandor has stated that the local manufacture of fuel cells is in line with government’s National Hydrogen and Fuel Cells Research, Development and Innovation Strategy, the ultimate goal of which is to supply 25% of world catalyst demand by 2020.



 

Edited by: Creamer Media Reporter

 

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Kell developer Keith Liddell talks to Mining Weekly Online's Martin Creamer on a new process that eliminates smelting and can take platinum from mining to manufacturing. Camerawork and Editing: Darlene Creamer and Shane Williams.
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