The stone wool manufacturer Paroc (a part of Owens Corning) considers blending in additional waste materials into the production to obtain a more sustainable product. By using waste material that otherwise would go to the landfill also less virgin raw material (volcanic rock) would be used. The waste material contains manganese (Mn) which may potentially affect the iron (Fe) redox equilibria that greatly affects the melt and product properties. Paroc therefor wish to understand and simulate the effect of blending in additional waste material in their product.