Reagents manufacturer and supplier Axis House has identified 2022 as the year to introduce its platinum-group metals (PGMs) range of technical reagents – comprising collectors, depressants and frothers – into the Southern African market.

These PGM-specific reagent types, in addition to flocculants that the company is still testing and refining, are being progressed “over the final product development hurdle” and will be introduced to the market in 2022. Axis House is prioritising the collector range for commercialisation, with depressants, frothers and flocculants to follow in due course.

“These products have been under development for the last five years. Axis House has invested extensively in research and development and our PGMs reagent range is ready to be rolled out into our target markets,” says Axis House sales manager Gareth Heynes.

The company’s development of its own PGMs range started at its metallurgical laboratory in Cape Town, in 2017. The first phase of PGMs collector testing is completed and results are being verified at customers’ laboratories before implementing at full scale, says Axis House technical manager Bernard Oostendorp.

Axis House is specifically targeting the first roll-out of the PGMs collector range in the north-western part of the Limpopo province, in South Africa.

91% of the world’s PGM reserves. PGMs consist of six metals: platinum, palladium, rhodium, ruthenium, osmium and iridium. Platinum, palladium and rhodium are the primary metals of significant economic value.

Their demand is diverse across four main segments, namely automotive (superb catalytic properties), investment (coins and bars), fuel cells, and other industrial purposes.

In 2020, prices for palladium in US dollar terms increased by 43.2% and rhodium by 187.2%. In Rand terms, rhodium prices climbed by 222.6%. These figures were calculated from data sourced from Statistics South Africa.

The company has also started conversations with operations in Zimbabwe and Zambia, which also have PGM deposits, Oostendorp says.

“The collectors’ development has been our key focus in trying to gain a foothold in PGMs processing and recovery, as well as in PGMs-associated base metals, such as your coppers and nickels – we’ve been working on multiple projects, all with differing mineralogy,” he adds.

Oostendorp notes that the company has narrowed the collectors product range down to about five collectors that have proven effective for specific PGMs mineralogy.

“So when you look at the UG2 reef, for example, we know it contains PGMs, but the reef’s chromite content can be a big issue, so we want to be sure that our collectors, especially, are highly selective to PGMs and base metals and reject chromite.

“The same goes for the Merensky reef – our collectors must be selective against those major impurities such as talc and pyroxenes and feldspar.”

Different Stages of Technical Reagent Development

Axis House focused on the base metal sulphides that offer high levels of pyrrhotite, pentlandite and chalcopyrite when developing the collector range, with three products – the TPG4, DPG4 and MPG 2. These products have undergone the most extensive levels of testing, Oostendorp enthuses.

“Once we roll out a specific product, the next step is to see if it can be applied in different ore types. If not, then we look at further refining that to suit that specific ore type or that specific mineralogy,” he continues.

Oostendorp notes that “an equivalent amount of work” went into developing the depressants to be applicable for these ore types.

“We've done extensive work on flocculants and all dewatering type chemicals in all our other industries, and based on our experience we believe that these reagents will be highly applicable to the PGMs market as well.”

He notes that the company conducted “some fine tuning to make the flocculants more specific” for PGMs applications, but adds that product tweaks will be a longer-term target for 2022, alongside working on the dewatering or solid liquid separation aspects for the market.

While developing these products, Axis House had to ensure that its products were low hazard and were compatible with existing mine safety guidelines.

The benefits of the technical reagents that Axis House is introducing to the market include ease of use and the reduction of pressure on the supply chain and cost reductions, says Heynes.

He adds that, when using a commodity reagent, the operation requires consumption of reagent, with operations then also needing to consider larger material storage and product handling strategies, whereas technical, or speciality reagents, require reduced dosage and therefore result in reduced logistical costs.

Oostendorp stresses that the aim of a reagent is always to maximise the concentrate grade and maximise recovery. “The difficulty with introducing new reagents into the market, is gaining insight into mining operations’ current process performance and their ore recovery percentages, and trying to improve their overall recovery,” he says.

Axis House’s collectors compete with well-known commodity reagents such as xanthates in the flotation of sulphide and oxide ores. Xanthates are used quite extensively on PGMs. Oostendorp notes that Axis House’s commodity collectors are fairly low in cost and work relatively well, pointing out that it is known that xanthates are not stable compounds, and their decomposition generates carbon disulfide, a substance that is considered toxic and highly flammable.