Even superfoods need their minerals

Using aluminium waste to grow better blueberries

In the Saguenay – Lac-Saint-Jean region of Quebec, Canada, we’re working with blueberry growers to make a safe and effective fertiliser. The best part? It is made from waste created by our aluminium operations.

~85% of waste material (excluding bauxite residue) created by our Saguenay – Lac-Saint-Jean Aluminium operations is used to make new products.

Anhydrite is a mineral normally found in rocks – but we produce around 85,000 tonnes a year in Quebec, Canada, as a by-product of our aluminium production process. Research shows this trusty mineral helps blueberry plants grow more leaves, longer roots and – most importantly – more fruit. Because it’s local, it is cheaper than many other fertilisers too. That is good news for local blueberry growers, who can at times face high costs and lower selling prices.

In 2019, we won an award from Québec circulaire – a local government-led initiative to boost the circular economy – for our reuse of anhydrite in agricultural and construction industries. And it has the Canadian Food Inspection Agency’s seal of approval too.

“Anhydrite contains calcium and sulphur – important nutrients for crops,” says Stéphane, a scientist in our Aluminium team. “It also helps improve soil texture and has no impact on pH levels, which all creates the right conditions for growing certain crops – like potatoes, wheat, barley – and now blueberries too.”

Stéphane is part of the nine-strong team of scientists, commercial and procurement experts who find ways to turn our waste into useful products, helping us reduce waste and create value at the same time. In fact, around 85% of the 400,000 tonnes of waste (excluding bauxite residue) created by our Saguenay – Lac-Saint-Jean aluminium operations is used to make new products.

But we did not stop there: Stéphane’s team has created other uses for anhydrite too. In construction, it is being used as an alternative to gypsum – a non-renewable natural resource – for cement and niche flooring materials. And in the paper industry, we partnered with Quebec’s Resolute Forest Products to explore the use of anhydrite in combination with sludge (organic material) from their paper mills – which, when combined could become an even more efficient "super fertiliser".

We are continuing to look for ways to improve the way anhydrite is used in agriculture too. We are funding research by Université Laval and Université du Québec à Chicoutimi, in partnership with the governments of Canada and Quebec, to provide even better data to farmers about anhydrite, helping them figure out exactly how much they need – based on their crop and soil specifications – to grow more blueberries. In spring 2021, we laid 32 tons of anhydrite in Albanel’s blueberry Co-op fields and are working with the growers to measure the impact on next year’s production.

“Collaboration is central to the success of a circular economy. By working together with partners we can be more successful in creating a sustainable future,” Stéphane says.

Banner image: Joanna Kosinska. Pullout blueberry image: Robert Zunikoff.

What about bauxite residue?

Bauxite residue, also known as “red mud”, is another waste product created during alumina refining. It is an industry-wide challenge, and one that our teams are working on around the world. In the Saguenay we have built a pilot facility in partnership with Global Mineral Recovery, which is testing a process for extracting minerals from bauxite residue.