Use of coal and metal-containing residue material as reductant during extraction of base metals

Purpose and goal
The aim with the project, to substitute a substantial amount of primary coal used as reductant by carbon containing residue material, has to a large extent been achieved. New knowledge has been generated showing the potential to utilise a residue material that today to large extent is landfilled, for reduction purpose in a metallurgical bath smelting process. By this, the residue material can substitute part of the coal used. Fundamental studies have led to two scientific papers, a licentiate thesis and a conference paper.

Structure and implementation
The project has been carried out in collaboration between industrial partners (Kuusakoski Sverige AB, Stena Recycling International AB and Boliden Mineral AB) and Luleå University of Technology. Fundamental studies have been conducted to characterise shredder residue material with respect to its reduction properties. This part has been included in a PhD work. Planning of plant trials have been through discussions and collaboration within the project group and from results from fundamental studies. Plant trials have verified results from fundamental studies and hypotheses.

Results
Results from the fundamental studies and full scale trials show the potential to use shredder residue material as reduction agents in metallurgical processes. However, the residue material has a much larger portion of volatile matter compared to primary coal. This means that reduction gas generated has to be utilised for reduction of molten oxides. The impact of a potential implementation of the concept is a new market for the residue material, increased resource efficiency and decreased dependency on primary coal.