Brendan Smith never intended to get into the critical minerals business. Initially, he thought his high-tech filters would be good for desalination. But he and his mentor, MIT professor Jeffrey Grossman, quickly dismissed it because it would be difficult to outperform existing systems. After “intentionally going off the rails” for a few years, they entered an entirely different industry: mining.
Producing critical minerals is no easy business. Take copper for example: the world uses around 25 million tonnes of copper per year, but demand is expected to grow by 24% over the next decade due to an increase in buildings, electronics and electric vehicles. For every tonne of copper ore recovered, around 100-150 tonnes of waste is left behind.
That's so much waste that some mines are running out of space in tailings ponds to store the toxic chemicals and by-products that are left behind after the valuable minerals are removed.
“If we don't have the land to build more of these ponds, we don't have a lot of options,” Smith told TechCrunch. Plus, these ponds are exposed to the elements, so when it rains or snows, it turns a manageable problem into a never-ending one.
For many mine operators, waste disposal is a costly part of their business, but Smith and Grossman's company, SiTration, has a different proposition: use its equipment to treat wastewater, and extract more minerals in the process.
“If we can do it cheaply and efficiently, which we can, we can recoup some of the cost of the repairs or even make a little bit of profit off the work,” he said.
The key, Smith says, is silicon. SiTration's filters are made on the same type of wafers used to make computer chips and solar panels, but they use a cheaper grade of silicon. To turn the wafers into filters, Smith and Grossman tweaked an existing chemical process and etched tiny holes into them. The resulting material is more durable than existing membranes and should last at least three years, depending on what's being filtered, Smith says.
The completed system would consist of a series of stacked wafers, with liquid running through them, and Smith says a larger mine would use about as much silicon as a medium-sized solar farm.
Because silicon is a semiconductor, SiTration can pass an electric current through the filter, making it even more effective against a range of minerals, including platinum, lithium, cobalt and nickel.
SiTration is starting with mine waste, including a pilot project with Rio Tinto, but is also marketing its filtration systems to battery recyclers and metal smelters, where its filters don't require heat and can reduce chemical use by up to 95%, Smith said.
Smith says SiTration's underlying technology remains the same for each industry it sells to: “We can ship the same box to multiple partners and customers.”
To build more boxes, the company has raised $11.8 million in a seed round led by 2150, with participation from Azolla Ventures, BHP Ventures, E14 Fund, Extantia and Orion Industrial Ventures.
The company plans to roll out the filtration system with various industry partners over the next few years, and depending on the size of the operation using it, “it will either be a very early demonstration for a very large mining partner, or a demonstration that's much closer to commercialization for a platinum-group metals refiner,” Smith said.