Selective separation of gallium from aluminum in SDS–Ga–Al and SDS–Ga–Al–fluoride systems by ion flotation

Selective separation of gallium from aluminum by ion flotation using sodium dodecyl sulfate(SDS) as an anionic surfactant and fluoride as an inorganic ligand was investigated. The experimental results were analyzed using the stability constants and speciation diagrams of fluoride metal complexes. The presence of fluoride in the solution has a positive influence upon the separation of gallium from aluminum. The results show that increasing the fluoride concentration makes a more effective separation of gallium from aluminum because of a simultaneous increase in the complexion of aluminum with fluoride and a change in the electrical charge of the aluminum(ALF_4^-). The dehydration model of LIU and DOYLE was also applied to compare the ion flotation and the selectivity coefficients of gallium over aluminum with experimental results.

Ion Flotation of Scandium

Scandium was recovered from dilute chloride solutions with potassium salt of saturated C_8～C_(12)fatty acids as surfactant by Ion flotation.The optimum comprehensive results of physical properties,stability and scandium concentration of the foam formed with potassium caprate CH_3(CH_2)_8 COOK can be obtained.Re- covery of scandium in the foam was 98% at pH 3.8～5.0 and 25～55℃.The experimental results of 0.3 L/min airflow rate was satisfactory for flotation column.It is of a great potential for using ion flotation technique to concentrate scandium from dilute solutions.

Treatment of a Polysulphide Ore by Ammoniacal Thiosulfate Solutions and Ion Flotation for Gold Recovery

Ammoniacal thiosulfate solutions with cupric ions have proved to be more successful than cyanidation in handling complex ores like carbonaceous and cuprous minerals. That＇s why cyanidation and ammoniacal thiosulfate leaching was performed at 33% of solids concentration in order to compare the efficiency of both techniques. Cyanidation delivered a gold recovery of 80.6% at 24 hours of agitation, whereas ammoniacal thiosulfate leaching achieved an 80.9% of gold recovery in only one hour of agitation. Then, the ammoniacal thiosulfate solutions obtained were submitted to five gold recovery techniques （carbon adsorption, cementation, adsorption on carbon impregnated with metallic copper, ion flotation and electrolysis） in order to determine which one of them was the most effective technique. Ion flotation proved to be the best technique due to its gold recovery of 84%. In addition, this technique only required trioctyl methyl ammonium chloride （Aliquat） and FloMin F-121 in a 0.1% concentration inside the solution. The small amounts of the flotation reagents allow the flotation concentrate to be treated by electrolysis. It was performed with 1.5 V during three hours and the resulting gold recovery was 82% in the cathode zone.

Removal of Safranine from Aqueous Solution by Using Adsorptive Bubble Separation Techniques

Safranine, a cationic dye, was removed from synthetic wastewater by ion flotation. Over 98% of safranine was removed from the solution in 10 min. A stoichiometric amount of surfactant (1 mol of surfactant to 1 mol of dye) was found to be most effective for safranine removal. The separation efficiency of safranine decreased with increasing concentration of NaNO3. Safranine was also removed by adsorbing colloid flotation technique using Fe(OH)3 as the coagulant. Sodium lauryl sulfate was used as the collector, and over 97% of safranine was removed in 5 min. The separation efficiency decreased with increasing ionic strength of the solution. The deleterious effect of neutral salt was compensated somewhat with the aid of Al3+ as the activator. Both ion flotation and adsorbing colloid flotation may be applicable in the removal of safranine from wastewater.