Most junior Platinum Group Metal (PGM) companies begin with exploration of a prospective project and look to leverage their way into the sector as a potential producer. Braemore Resources, however, is taking a different route in its bid to be a PGM mine to metal supplier. It is using different smelting technology to achieve its goal.
The traditional smelting technology for PGM processing is the use of six-in-line submerged arc furnaces, which smelt the ore at 1,400O to 1,600O C. Sulphur is used as the collector and a sulphurous matte is produced. The limitation of this proven technology comes with more UG2 ore being mined, which increases the likelihood of high chrome content in the ore; anything greater than 2.5% chromite content is a problem for submerged arc furnaces.The chromite forms spinnels in furnaces and the formation of such a build-up along the furnace’s inside walls makes it progressively more difficult to operate the furnace.
“Together with Mintek and our other partners we have looked into ways of avoiding this problem,” Braemore Resources CEO Leon Coetzer says. “There are two options. One is to ensure the concentrate does not exceed 2.5% chrome content, but that is throwing the problem back upstream. The other is the ConRoast process.”
The ConRoast process is based on the removal of sulphur by roasting, followed by smelting of the dead-roasted concentrate in a DC arc furnace, adding a reductant and then using an iron-based alloy as a collector for the PGMs. Braemore has a ten year exclusivity deal with Mintek relating to this technology, with September 2009 marking the completion of the third year of the development phase. During the next seven years, Braemore will commercialise this technology developed and patented by Mintek.
“We look at where the technology can add true value, and this includes new off-takers as well as existing sources. We have spoken with most of the juniors in the PGM sector,” Coetzer says. Existing UG2 recovery processes lose some 15% of the PGMs in the concentration phase and with the ConRoast technology these losses could be reduced by 2.5% to 6% depending on the ore grade recovery curve.
The technology is unique in that it entails no chrome penalties. Existing off-take agreements provide rapidly decreasing payments for ores that contain higher levels of chromite, as the smelters bid to ensure they get the highest quality concentrate possible.
“An advantage of the new technology, which has a temperature of about 16,000O C at the arc, is that it is a clean process from an environmental viewpoint.” The sulphur is removed from the enclosed roasting equipment in a continuous stream of SO2, which can be fed to a sulphuric acid plant.
It is also a modular process. “There is a smaller footprint over the whole process, when one takes into account that there are fewer unit steps than in a conventional smelter.
” The DC arc breaks down the minerals in the concentrate to their constituent elements and there is no semi-smelted material. The ConRoast technology has been used to successfully treat ores with between 2.5% and 11% chromite content, which is captured in the slag. To date the smelting of the PGM containing ore has been done in a 1.5 MW pilot plant located at Mintek in Randburg.
The resulting iron-nickel alloy contains 600 – 1,000 g/t of PGMs, which can be hydrometallurgically treated to remove the iron. The PGMs are concentrated into a final concentrate containing about 65% PGMs. R&D into the hydrometallurgy is underway, with two technical partners.
The ConRoast technology appears to be financially robust with the demonstration furnace able to cover its costs. To date Braemore has produced 15,000 ounces of 4E and by the end of 2008 this will have increased to 20,000 ounces.
Braemore Resources has a three-phase plan for growth, the first phase being the development of the furnace technology. This has seen the build up from the 1.5 MW demonstration unit to a 3.2 MW furnace at the Mintek site at a cost of R33 million, which takes the furnace size to the limits of Mintek’s capacity. The four week upgrade began on September 8th. Braemore’s staged approach has been to show that the process is sound and that the engineering works. The 3.2 MW smelting unit will see the company produce about 70,000 ounces a year of 4E, depending on the feed grade of the concentrate.
This is to be followed by a full sized 10 MW commercial unit to be commissioned either on the Western or Eastern Limb of the Bushveld Complex by the end of 2010. This fits into the plans of new projects due to come on stream within the next two to four years, and will see the company break the 200,000 ounce a year mark. A 10 MW unit will produce some 150,000 to 200,000 ounces of 4E PGMs a year of which roughly 57% will be platinum. Braemore has raised R100 million to carry out its activities to date and will look to raise the funding for the 10 MW furnace project either at the end of this year or early in 2009.
A bankable feasibility study undertaken by TWP Consulting was completed in July and was under internal review by Braemore at the end of August 2008. This review process was running concurrently with negotiations relating to joint venture BEE partners and off-take agreements. Electricity is an issue and Coetzer says that while power has been allocated for the 3.2 MW furnace Braemore is in negotiations with Eskom for the 10 MW plant.
There are a number of advantages that aid Braemore in presenting its case. “For one thing it is an energy efficient process because there are fewer unit steps in the smelter complex. Secondly, its modular nature makes it easier than to consider than, say, a 40 MW plant. Thirdly, it is a South African developed technology which will benefit the South African PGM sector.
” Phase two of Braemore’s strategy involves using the ConRoast process as a catalyst to enter the PGM mineral resources and mining sector, even at the exploration stage. This could involve equity swaps, ownership of a producer, or pool and share arrangements justified by the use of the ConRoast process.
The third phase would be to build up a critical mass, incorporating at least three 10 MW modules, in the smelting phase to produce sufficient alloy to invest in a refinery. Braemore is working with technical partners to ensure the alloy produced is suitable for the refining phase.
Right now, though, the priorities are finalising the key partnerships, completing the furnace research and development and feasibility review and securing funding for the next level of furnace capacity. Coetzer, who is a chemical engineer and was part of the technology team at Anglo American, and who also has an operational and then management background in the industry, says that the technology path is proven and is not seen by investors as the biggest risk; rather the sourcing of off-take agreements is the next challenge faced by the company.
“While we have not taken a traditional high risk path to enter the sector, and have used a lower cost lower risk entry point through identifying a beneficial technology, our aim of mine to metals is similar to that of most other juniors in the PGM sector,” Coetzer says.