A process is described for the treatment of carbon steel electric arc furnace dust to remove zinc, lead, copper and cadmium as sulphides, potentially saleable to a zinc plant, followed by recycling of the iron oxide residue to the steel producing furnace. Clean gypsum, expected to be saleable, is a by-product. The process uses a strong acetic acid leach to dissolve most of the heavy metals and calcium. hydrogen sulphide to precipitate the heavy metal sulphides, and sulphuric acid to precipitate calcium as gypsum. The regenerated acetic acid is treated by ion exchange to remove impurities. The acetic acid is reconcentrated by distillation or other means for recycle to strong acid leaching.
