Will The Kell Process Revolutionise The Platinum Industry?

By Alastair Ford

It was back in the days when he was still with Aquarius Platinum that Keith Liddell starting thinking in earnest about what was eventually to become the Kell Process. Kell is, in simple terms, an evolving new technology that provides the platinum industry with an alternative to smelting.

And its origins are fairly straightforward. “In Aquarius days”, explains Keith, “the majors said: ‘we don’t want any juniors on our patch, we won’t take your concentrate’. That left us with two alternatives – ship overseas, or do our own processing”.

In the event, the majors changed their tune, and Aquarius’s unique way of operating went on to change the way mining and business was done on the Bushveld. So there was no need for alternative processing methods at that particular critical juncture after all.

Even so, the rationale behind Aquarius’s original plans never quite went away, as the majors continued to dominate, and juniors still found it hard to squeeze in. More to the point, the smelting of ore from the Bushveld has become increasingly difficult over the years as miners are increasingly turning their attention to harder-to-process rocks, having mined out all the easy stuff.

In due course Keith moved on, and with him went one of the alternative options that had been under consideration during those formative years for Aquarius - Kell. He subsequently took a key role at Platmin, which is now tucked safely under the wing of Brian Gilbertson’s Pallinghurst, but all the while he was thinking about Kell, and its possible applications. Its key feature, says Keith, is that it dispenses with the need for smelting.

To explain, he sketches out in simple terms the traditional process that takes ore from the ground and turns it into finished metal. “You dig it up, create a flotation concentrate, put it into a smelter, which uses 1,000 kilowatts per tonne of concentrate, then send it to a base metals refinery, and then to a platinum group metals (PGM) refinery.”

Kell reduces that extensive power consumption by dispensing with the smelting stage all together. “Ninety per cent of the concentrate is waste minerals”, says Keith. “Smelting raises the temperature of all of those up to 1,600 degrees and then melts it, using electricity. We take the concentrate and we just leach it.” The leach process that underpins Kell actually has two separate stages. The first stage is pressure oxidation, to leach out all the base metals. The second is a heat treatment, during which the PGMs leach out. Simple as that.

Except, of course, that the viability of Kell has yet to be proved at a commercial level. But Keith has high hopes. The technology behind pressure oxidation, he points out, is pretty standard, as is the technology behind heat treatment.

So he’s not exactly asking his customers to help him re-invent the wheel. Two scoping studies on the application of Kell to specific ore types have already been completed, and four more are ongoing. Definitive studies are due later this year. And it’s not only South African ores which are getting the Kell treatment. North American ores from Sudbury and Duluth have also been run through the process, with highly encouraging results.

“The major costs”, says Keith, “are labour, acid, which can be recycled, and electricity. The largest bit of kit is the kiln. More to the point, the application of Kell should save between 20 per cent and 30 per cent of the capital costs of any given project. “A 250,000 ounce per year Kell plant would likely cost around US$50 million”, says Keith, as against the probable US$80 million for a smelter. These are big numbers, but the saving is considerable.

Kell does have some detractors. Supporters of Jubilee Platinum, which plans to scale up its processing of platinum ores through DC furnaces, remain sceptical. But Keith is a seasoned platinum industry veteran, who cut his teeth in the South African research institute Mintek in his young days as a minerals engineering graduate and certainly knows a thing or two about the business.

It’d be interesting to sit Keith down with representatives from the Jubilee side for a formal debate on the pros and cons of each process. Perhaps we could even video the event and post it on Minesite.