Patent ID: 7815709

Claim:
An electro-hydrometallurgical process that extracts zinc from electric arc furnace dust to produce zinc of high purity and fine particle size, comprising: leaching electric arc furnace dust with an alkaline solution to form a zincates solution; separating the zincates solution into a liquid portion and a gangue portion; inertizing the gangue portion; purifying the liquid portion by cementation and separating precipitated solids from the liquid portion; purifying the liquid portion by adsorption, wherein the liquid portion is submitted to adsorption by percolation with Ba(OH) 2 to substantially eliminate arsenic and is substantially continuously percolated on a fixed bed of Ba(OH) 2 operating in countercurrent or crosscurrent stages and having an adsorption capacity, with a load of Ba(OH) 2 between about 3 and about 10 times over a stoichiometric amount required for adsorption according to the chemical reaction As 2 O 5 +2Ba(OH) 2 (s)→2BaHAsO 4 (s)+H 2 O and once the adsorption capacity of the bed is exhausted, the bed is removed, dried and disposed of in a waste disposal site; at least partially evaporating a resulting purified solution to form a concentrated solution; bleeding at least a fraction of the concentrated solution; crystallizing at least a fraction of the concentrated solution; electro-depositing zinc from the concentrated solution; and separating, washing and drying deposited Zn.