Many of our products contain copper which is lost when we throw them away. The products end up in a waste to energy incinerator which leaves bottom ashes as residue. In these bottom ashes, many small fractions of copper are available, which are not being recovered. Typically, the bottom ashes of the incinerator end up in building materials under highways. With precious metal prices soaring over the recent years and their scarcity increasing as well, the business case to recover these materials becomes more interesting. In 2009, Dutch startup Elemetal developed an unique washing process to extract copper and zinc from bottom ash and thereby closing the loop. This is a good example of how the circulair economy should work. Moreover, the copper recovered from bottom ash is often richer in copper than most copper ore grades, defining this process more as upcycling copper than recycling it.
Expanding into other waste streams
Elemetal has ambitions to expand their services into other waste streams such as mine tailings, slag and filter residue. Tailings and waste rock dumps in mining still contain significant amounts of valuable metals. Traditional mining techniques often have low yields on these difficult minerals. It is estimated that per tonne of copper 2.2 tonnes of slag is produced from copper smelters. This copper is currently not or barely recovered and after applying it as a building material it is considered to be lost. Besides this, leaching of heavy metals (mainly copper) from the copper slag into ground waters has a negative environmental impact.