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.