The ore's own energy creates a purification process

10 June, 2022

The success with which ore can be desulphurised in an environmentally sound and cost-effective way can mean the difference between mining an ore and leaving it in the ground. In a Vinnova-funded prestudy metals research institute Swerim has demonstrated that just such a method could be viable.

“We have tested an idea that appears to hold up well in a laboratory setting. Here, we're talking in terms of grams, not industrial-scale tonnes. But, at this level, we are very pleased,” says Mikael Larsson, business area manager for Metallurgy at Swerim.

The method concerns thermal decomposition to remove sulphur via so-called roasting.

“We hypothesised that heating the concentrate up to 600 - 650 degrees would be enough, but it was evident that it would take 900 degrees for the sulphur to be totally removed. However, this is a cost-effective method, since the temperature increase is driven by the chemical energy present in the ore,” explains Mikael Larsson.

The mining company Kaunis Iron, in Pajala, has shown great interest in the results of the prestudy. The mineralisation in Sahavaara, in Pajala, has high sulphur content and the company has applied for an environmental permit for desulphurisation of the ore via flotation. The method tested in Swerim's prestudy just might prove to be both more cost-effective and better from an environmental point of view.

“Swerim's prestudy is very inspiring from a development perspective,” says Per-Erik Lindvall, who is a board member of Kaunis Iron. “To be able to use the energy which the ore, itself, brings to the process is highly interesting and this points to a way forward for fossil-free steelmaking. We will continue working along this track.”