Mineral wool made from residual products from the aluminium industry?

12 May, 2022

A successful research project demonstrates the possibility of manufacturing mineral wool with less environmental impact than methods currently used. Anodising sludge, a secondary resource from the aluminium industry, can be used in the manufacture of mineral wool, since it is technically feasible to briquette the sludge.

To be able to apply this in industrial scale, larger-scale trials will be necessary before we can say anything conclusive, for example, about the effects of emissions, but the results of the project are both hopeful and interesting.

In the surface treatment of aluminium products using anodising, the residual product is an anodising sludge that contains aluminium hydroxide. In Sweden a small portion of this sludge is used in the production of water purification chemicals, but most of it is landfilled. An estimated 8,000 tonnes of the anodising sludge produced in Sweden ends up in landfills. Some 6,000 tonnes originates from the companies that participated in the project.

Briquetted sludge

“Naturally, landfilling isn't the ideal solution, neither from an ecological nor an economical point of view,” explains Sara Rosendahl. In the AluKrets-II project, Sara has demonstrated that the sludge could, instead, be used in the manufacture of mineral wool, since the residual product contains aluminium hydroxide.

Researchers in the AluKrets-II have shown that it is technically possible to make briquettes from the sludge. These briquettes could be used in cupola furnaces, which are currently used in the production of mineral wool in Sweden.

“The challenge was to find the optimal material blend for briquettes made from sludge. We succeeded in doing that in the scale we worked with in the prestudy. It has been rewarding working in close to the industry, in collaboration with our project partners, and we came up with the answers we were looking for at this stage,” concludes Sara Rosendahl, Swerim.

Facts

The recently concluded AluKrets-II has been funded by Vinnova, Formas and the Swedish Energy Agency via the strategic innovation programme Metallic Materials. Project manager Sara Rosendahl, Swerim, is satisfied with the outcome

AluKrets-II has been carried out in close collaboration between Swerim, Hydro Extrusion Sweden, ProfilGruppen, Klarvik, Ahlins and Paroc. The total project budget was 1.96 million kronor, of which 980,000 million kronor was funding from Vinnova.