During prototype tests the technical and economical feasibility was tested for co-refining of copper and zinc from heavy-non-ferrous flows. From a technical point of view the tests where successful. LME grade A was produced, and zinc sulphate was produced at a marketable solution and as zinc sulphate heptahydrate crystals.
From an economic point of view the conclusion was that the scale needed to implement such a process would be significant and would lead to a big challenge. Therefore it was decided to simplify the technology and put more focus on the recovery of zinc. This led to the plan of splitting the demonstration into 2 phases where first the recovery of zinc from bottom ashed followed by zinc leaching was introduced on DEMO scale followed by further upgrading of the zinc solution to a viable zinc derivative product during a second demonstration phase.