A PROCESS FOR THE TREATMENT OF ELECTRIC AND OTHER FURNACE DUSTS AND RESIDUES CONTAINING ZINC OXIDES AND ZINC FERRITES

摘要

The present invention is a method of recovering valuable metals from a quantity of furnace dust consisting the following steps. A first leaching step wherein the furnace dust is leached at atmospheric pressure in a first leaching solution to produce a first leach liquor and a first leach residue, the first leaching solution consisting of an aqueous mineral acid solution. The first leach liquor is then separated from the first leach residue. A second leaching step is then performed wherein the first leach residue is atmospherically leached in a second leaching solution to form a second leach liquor and a second leach residue, the second leaching solution comprising a solution of aqueous HCl with a reductant. The second leach liquor is then separated from the second leach residue. A zinc precipitation step is then performed wherein zinc is precipitated from the second leach liquor by treating the second leach liquor with a quantity of alkali, the quantity of alkali selected to adjust the pH of the second leach liquor sufficiently to precipitate out the zinc in the form of a zinc salt in a third residue leaving a third liquor and then separating the third residue containing zinc from the third liquor.