Process for the recovery of zinc, copper and cadmium in the leaching of zinc calcine

Abstract From the Canadian patent

Zinc, copper and cadium are recovered from their ferrites by subjecting the ferrites to a sulfuric acid bearing solution in the presence of potassium, sodium or ammonium ions under atmospehric conditions at 80-105°C to precipitate the iron present in the ferrites as jarosite, separating at least a portion of the jarosite-bearing solid material from the solution before recycling the solution to a neutral leach from which a, copper and cadium bearing solution is recovered and to which acid and clacine are also fed, feeding the solid obtained from the neutral leach to the said ferrite treatment stage classifying the solid obtained from the neutral leach into a finer and coarser fraction, …