According to circular principles, the recycling of existing products and materials is lower in the hierarchy of circular models. It still can however, provide a useful element within circular design once the product lifecycle after all other possibilities for reuse have been exhausted. Fortunately, galvanized steel is readily recycled.
At end of life – and if reuse is not feasible – galvanized steel can be recycled easily with other steel scrap in the electric arc furnace (EAF) steel production process. Any zinc remaining from the coating volatilises early in the steel recycling process and is collected in the EAF dust that is then recycled in specialist facilities and often returns to refined zinc production.
Waelz kiln process
Since the early 1980s, the well-established Waelz kiln process has been used to process EAF dusts that contain valuable zinc and other elements. An impressive 98% of EAF dusts produced by Europe’s steelmakers are recycled.
The Waelz kiln process is the most commonly-applied method to recycle these dusts but various other innovative processed have also emerged, including the rotary hearth furnace; multiple hearth furnace and low hearth furnace.
A key driver for the recovery of these dusts is their zinc content. The wider use of zinc for coatings on steel, in particular in the automotive sector, has increased EAF dust zinc contents to levels that make their recovery economically attractive. Generally, zinc contents greater than 15% in the EAF dust make recovery economically viable and most dusts are at this level.