EAFD (Electric Arc Furnace Dust) is a waste by-product from every Steel plant in production, containing typically between 12 and 20 kg of EAFD produced for every ton of steel being recycled. EAFD generally contains between 18% and 25% zinc, which is multiple times richer than most Zinc exploration companies exploiting zinc deposits containing less than 30% of Zn of a typical EAFD feed quantity. In addition to zinc the EAFD contains 22% to 30% of iron and 1% to 3% of lead as well as cadmium and cobalt.
Steel scrap is recycled in electric arc furnaces by a simple remelting process, accounting for about one third of global steel production annually. Steel objects are increasingly galvanized to protect them from corrosion, involving the coating of steel with a thin layer of zinc. As more steel is galvanized so too scrap contains an increasing amount of galvanized material. When the scrap is recycled, the zinc from galvanizing, together with other base metals, alkalis and halides, are driven as a dust and caught up in the flue gasses. These fine particles need to be filtered out before the furnace gasses can be returned to the atmosphere. The filters are periodically cleaned and the resulting dusty material is known as electric arc furnace dust or EAFD.
Conventional recovery of zinc from EAFD has never been possible to date. Simply, economics of the cost and energy needed in zinc recovery from the dust means that incumbent processes are a negative return on investment and is therefore considered to be not viable. Furthermore, since EAFD also contain traces of toxic elements such as cadmium, arsenic, cobalt, lead and mercury, it is classified as a hazardous waste. EAFD has been processed for many years using very energy intense and costly Waelz kiln technology but this not only does not recover the iron, the zinc recovery percentage is less than 50-60% of what is contained within.
Since the cost of landfill in many countries is less than the subsidy required to justify the development of a sustainable technology, the EAFD continues to be landfilled. Currently it has been estimated that there are about 7 million tonnes of EAFD generated annually worldwide.
Neomet Technology is capable of recovering >95% of all Zn from the EAFD, along with hi-purity Iron (Hematite) and every other associated by products such as Cadmium, and Lead, both marketable commodities in the micronutrient industry.
