Separation of Metal Values in Zinc Leaching Residues

Abstract

The invention relates to the separation of metals in Fe-bearing zinc leaching residues, in particular neutral and weak acid leach residues. The process comprises the steps of: preparing agglomerates containing, besides the Zn leaching residue, at least 5 wt % of carbon and 2 to 10 wt. % of S; fuming said agglomerates in a static bed at a temperature above 1250° C., thereby producing a reduced Fe-bearing phase and Zn-bearing fumes; and extracting said Zn-bearing fumes. The high S content of the feed allows for a relatively high operating temperature without production of molten phases. This guarantees fast reduction and fuming kinetics, and permits the use of a compact technology such as a static bed furnace.

1 - 10 . (canceled) 
     
     
         11 . Process for the separation of metal values in a Fe-bearing Zn leaching residue comprising the steps of:
 preparing agglomerates containing a Fe-bearing Zn leaching residue, at least 5 wt % of carbon and 2 to 10 wt. % of S;   fuming the agglomerates in a static bed at a temperature above 1250° C., wherein a reduced Fe-bearing phase and Zn-bearing fumes are produced; and   extracting the Zn-bearing fumes;   wherein metal values of the Fe-bearing Zn leaching residue are separated.   
     
     
         12 . Process according to  claim 11 , further comprising the step of drying the Fe-bearing Zn leaching residue to a moisture content of less than 12 wt. % H 2 O, before the step of preparing agglomerates. 
     
     
         13 . Process according to  claim 11 , further comprising the step of drying the Fe-bearing Zn leaching residue to a moisture content of less than 5 wt. % H 2 O, before the step of preparing agglomerates. 
     
     
         14 . Process according to  claim 11 , wherein the agglomerates comprise at least 15 wt. % of carbon. 
     
     
         15 . Process according to  claim 11 , wherein the agglomerates further comprise a Ca compound, the Ca compound having at least 10 wt. % of CaO equivalent in the agglomerates. 
     
     
         16 . Process according to  claim 14 , wherein the agglomerates further comprise a Ca compound, the Ca compound having at least 10 wt. % of CaO equivalent in the agglomerates. 
     
     
         17 . Process according to  claim 11 , wherein the agglomerates further comprise a Ca compound, the Ca compound having at least 15 wt. % of CaO equivalent in the agglomerates. 
     
     
         18 . Process according to  claim 14 , wherein the agglomerates further comprise a Ca compound, the Ca compound having at least 15 wt. % of CaO equivalent in the agglomerates. 
     
     
         19 . Process according to  claim 11 , wherein the agglomerates are pellets having a Mass Pellet Strength of at least 5 kg. 
     
     
         20 . Process according to  claim 11 , wherein the agglomerates are pellets having a Mass Pellet Strength of at least 10 kg. 
     
     
         21 . Process according to  claim 11 , wherein the fuming step temperature is at least 1300° C. 
     
     
         22 . Process according to  claim 11 , wherein the fuming step is carried out in a carbon monoxide containing atmosphere. 
     
     
         23 . Process according to  claim 21 , wherein the fuming step is carried out in a carbon monoxide containing atmosphere. 
     
     
         24 . Process according to  claim 11 , wherein the Fe-bearing Zn leaching residue is a neutral or weak acid Fe-bearing Zn leach residue. 
     
     
         25 . Process according to  claim 11 , wherein the fuming step is carried out in a rotary hearth furnace. 
     
     
         26 . Process according to  claim 21 , wherein the fuming step is carried out in a rotary hearth furnace. 
     
     
         27 . Process according to  claim 23 , wherein the fuming step is carried out in a rotary hearth furnace. 
     
     
         28 . Process according to  claim 11 , further comprising the step of subjecting the reduced Fe-bearing phase to an oxidising smelting step. 
     
     
         29 . Process according to  claim 21 , further comprising the step of subjecting the reduced Fe-bearing phase to an oxidising smelting step. 
     
     
         30 . Process according to  claim 23 , further comprising the step of subjecting the reduced Fe-bearing phase to an oxidising smelting step.