Challenge the practice is addressing: It is estimated that Boliden's Kokkola zinc smelter in Finland produces approximately 820,000 tonnes of wet sulphur residue (330,000 dry tonnes), which are currently treated as waste but can be converted into valuable metals.
Concrete practice to achieve the expected goal: Sulphur residue was placed in separate ponds for several years until the early 2000s. The sulphur residue contains approximately 70 percent of elemental sulphur, as well as about 30 percent of metals like zinc, silver, and lead that can be recovered. Prior attempts to clean sulphur of impurities have failed, and there is no real market for impure sulphur. Instead, they have developed new capabilities to dewater and find the right agglomeration recipe before the sulphur residue is fed into the roaster.
Expected impact/goal of the practice: The aim is to minimize the amount of waste. Sulphur residue can now be safely removed from landfills using the technique they developed.
Who is the target user group of the practice/intervention or implementing the practice/intervention? This practice is mainly relevant for industry contexts.