Process for separating and concentrating gallium from an aqueous solution containing gallium, together with aluminum, zinc and copper

A process for separating and concentrating gallium from an aqueous solution containing gallium together with aluminum, zinc and/or copper, comprising the steps of:

• a) preparing a water-in-oil emulsion in a homogenizer, the emulsion being prepared from a neutral or alkaline aqueous phase and an organic phase, the organic phase containing an oil-soluble reactant, the oil-soluble reactant comprising a secondary amine and a non-ionic surfactant, the emulsion having a ratio by volume of aqueous phase to organic phase of from 2:3 to 3:2;
• b) dispersing the emulsion in the aqueous solution in an extractor in a ratio by volume of aqueous solution to emulsion of from 30:1 to 10:1 until emulsion droplets having a diameter up to 1 mm are obtained, the aqueous solution containing at least 4 mol/l of HCl;
• c) removing the emulsion from the aqueous solution and breaking the emulsion in a reactor using an applied high voltage alternating field having a field strength of at least 0.5 kV/cm and a frequency of more than 50 Hz to form an electrocoalesced organic phase and an electrocoalesced gallium-containing stripped-off aqueous phase, the reactor having coaxial, double insulated electrodes, and returning an unbroken portion of the emulsion to the extractor;
• d) removing the electrocoalesced organic phase in a gravitational separator and returning the electrocoalesced organic phase to the homogenizer.