Process for concentrating and recovering gallium

A process for treating phosphorus-furnace flue dust containing gallium, zinc and aluminum which comprises the steps of:

• 1. treating flue dust with sulfuric acid for formation of a leach solution and a leach residue;
• 2. separating leach solution from leach residue;
• 3. precipitating zinc in the leach solution in the presence of ammonium sulfate as zinc ammonium sulfate hexahydrate;
• 4. separating precipitated zinc from the solution;
• 5. adding an alkaline material to said solution for the precipitation of a first gallium concentrate and the formation of a first gallium-free solution;
• 6. separating first gallium concentrate from first gallium-free solution;
• 7. mixing first gallium concentrate containing phosphate in a slurry with lime in an amount which is at least stoichiometric to the phosphate content of the concentrate to form a precipitate comprising calcium phosphate and coprecipitated gallium and aluminum compounds in a gallate-aluminate solution, adding an amount of a suitable alkaline material sufficient to raise the pH of the slurry to at least 11 whereby coprecipitated gallium and aluminum compounds are redissolved in the gallate-aluminate solution and whereby a residual precipitate remains;
• 8. separating said residual precipitate from said gallate-aluminate solution;
• 9. neutralizing said gallate-aluminate solution with acid for precipitation of upgraded gallium concentrate and formation of a second gallium-free solution;
• and
• 10. separating upgraded gallium concentrate from second gallium-free solution for recovery of upgraded gallium concentrate.