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.