On Feb. 20, the Boston, U.S.-based biotechnology company Allonnia announced that it had recently completed a demonstration of its recyclable biosolution at SGS’s metallurgical lab in Lakefield, Ontario, that it said validated the solution’s efficacy in a continuous process.

This biosolution is a key component of Allonnia’s D-Solve process, which is a bolt-on solution that can be added onto an existing mineral processing flowsheet with the aim of increasing the grade of the mineral concentrate, while also reducing waste and lowering CO2 emissions.

“D-Solve is a biologically generated solution that selectively solubilizes gangue minerals from flotation concentrates,” Chuck Price, chief commercial officer at Allonnia, told CIM Magazine in an interview at SME’s MINEXCHANGE annual conference and expo in Denver, Colorado, on Feb. 25.

The D-Solve process has three steps: agitated leach, solid-liquid separation and biosolution regeneration. First, the stream of flotation concentrate is sent to an agitated leach tank where a bio­solution dissolves the gangue minerals. Next, the purified concentrate is removed by filtration and returned to the main mineral processing system. Finally, the concentrate impurities are removed, and the biosolution is returned to the leaching step.

“The end result is that you’ve got an upgraded mineral concentrate with a higher proportion of whatever it is you’re trying to capture—nickel, copper, lithium—and less penalty elements or gangue materials in that concentrate,” said Price.

“The unique feature of it is [that] we’re using microbes that are naturally occurring on mine sites. They’re already expressing these metabolites as part of their biological processes—they’re breaking things down, they’re weathering them. We use those microbes to generate this biosolution; not at the mine site itself, but in a bioreactor. Nobody else is really doing anything like this.”

Another advantage of the D-Solve process is that it is designed to be added to existing mineral processing plants. “If you look at lots of other technologies where they’re developing something new to remove the metal of interest, none of those technologies fit with current plants,” explained Dan Stigers, vice-president of business development at Allonnia, in an interview with CIM Magazine at MINEXCHANGE.

The demonstration of Allonnia’s biosolution with SGS used nickel-sulfide concentrate that was supplied by BHP through its innovation team, Think & Act Differently. The biosolution reduced magnesium impurities in the concentrate by 40 per cent, while increasing the nickel grade by 18 per cent.

“The goal was to try to remove as much magnesium impurities as we could; the reason for it is that magnesium makes it hard to turn nickel concentrate into nickel metal,” said Stigers. “We ran [the trial] continuously for about six days straight, [and] we were able to remove a consistent 35 to 40 per cent of the magnesium out. We saw an 18 per cent increase in the nickel grade, which means now the concentrate that the customer can sell is a lot more valuable.”

Stigers also noted that there was no degradation in the components of the biosolution over the course of the demonstration. “We went through six or seven turnovers, which means all of the [biosolution] volume was recycled at least once,” he said. “[That] means it survived continuous operation for at least a week, and at temperature.”

While the SGS trial used nickel-sulfide concentrate, the D-Solve process can be used for other commodities as well. Price said that Allonnia has been working with several concentrates in its laboratory, including lithium concentrate, molybdenum concentrate and copper concentrate.

Once the solution is fully implemented across the processing flowsheet, Allonnia stated in its Feb. 20 press release, downstream costs are also expected to be reduced by the removal of impurities from the concentrate.

“Each of the mine sites has their challenge that they’re working on, and they’re interested to see what we can do,” said Price. “In some cases, they’ve got particular penalty elements—for example, deleterious elements like fluorine—that they want out of the concentrates. Those are smaller proportions, but they’re really problematic downstream. If you’ve got fluorine in your concentrate and you send it to a smelter, it’s going to make hydrofluoric acid and it’s going to eat up the smelter.”

There can be environmental benefits to the process as well; in some cases, D-Solve can create a potential path for CO2 sequestration.

For example, the magnesium impurities removed from the nickel-sulfide concentrate could be used to sequester CO2 and create magnesium carbonates instead of sending them to tailings or slag. “In this process, since we’re removing these impurities, they can be used as a source of CO2 sequestering,” explained Stigers. “You could offset a portion of the plant footprint.”

He also noted that magnesium impurities can cause the temperature of the smelter to increase. “By getting rid of [them], the smelter can also run at a lower temperature,” he said. “And you could sequester the CO2 at the same time, so you get a double benefit. Obviously, we want to boost metal production, but if you could do it with a smaller carbon footprint than what you were doing before, that hits a lot of environmental, social and governance targets for a lot of companies.”

Stigers added that removing the gangue reduced the mass of the concentrate by approximately 20 per cent. “Imagine transporting the same amount of product with 20 per cent less mass—that’s a lot less CO2 in the air, and a lot less energy costs for transportation,” he said. “The farther your customer is, the bigger that impact.”

Allonnia stated in the press release that the successful demonstration with SGS was an important step towards commercializing its D-Solve process. The company already has several mining partners, and Stigers said that it would be doing its first on-site testwork with a partner very soon. “We’ve already got a sample of their material [and] done the work in our labs, [which is] all promising,” he revealed.

Later this year, the company plans to invest in a mobile pilot unit that will enable onsite validation of D-Solve’s performance at mine sites that have challenges with impurities in their concentrates. “That way, we can run [the process] at a realistic scale, [and] the customer can get a feel to validate the economics and the technical assessment,” Stigers explained.

Allonnia also has an interest in working with operations in Canada. “There are a lot of nickel operations in the Sudbury region, and those are very interesting target customers of ours,” said Price. “And in western Canada, you’ve also got some interesting copper mines, [so] there could be potential operations for us.”

Stigers pointed out that as the demand for nickel increases, technologies such as D-Solve could help nickel operations in countries such as Canada and Australia keep their cost of production down in a difficult global market. “Making [production] less expensive but more efficient helps make that nickel more viable for those 21st century applications like EV batteries,” he said.