The electroflotation process of extracting a mixture of Cu, Zn, Ni, Co, Fe hydroxides from wastewater containing NaNO3, NaCl, Na2SO4, Na2CO3, Na3PO4, NH4OH has been investigated. It was found that the maximum recovery rates of 97-99% are observed in the pH range from 8 to 11 for NaCl solutions. The electroflotation process is the least effective in Na3PO4 solutions with recovery rates of 10-20%. The cationic surfactant SeptaPAV-SKhV- 70 (CentafAB-70) added to the solution increases the extraction ratio in the presence of phosphates by 40-50%. Low efficiency of the electroflotation process in Na3PO4 is associated with a small particle size (about 20-30 mu m) and a zeta-potential high negative value, what has an injurious effect on the formation of the flotation complex, negatively charged bubbles (H-2, O-2) and negatively charged particles. The addition of a cationic surface-active substance (SAS) reduces negative potential of the dispersed phase and increases particle sizes. All this contributes to the efficient passing of electroflotation process. Presence of a ligand (ammonia solutions) in the sewage reduces the recovery efficiency by 20-30%, especially for copper ions, which are strong complexing agents. Adding to the solution of small amounts (5 mg/l) of industrial surfactants STMs(a) (CTMx(a)) and Flon-1(c) (phi pi omicron H-1(kappa)) at total concentration of hydroxides of 100 mg/l leads to a more efficient passing of the electroflotation process. A process flowsheet for removing suspended matters (a mixture of metal hydroxides) using an electroflotation cell and a microfiltration module is proposed. A model series of electroflotation devices with a capacity of 1-10 m3/h was proposed for application of the described technical solutions. The separation time in the devices does not exceed 10 minutes, power inputs is up to 0.6 kW. h per 1 m3 of the treated wastewater with a recovery rate of 97-99%. The cost of an installation for 10 m3/h does not exceed 1.5 million rubles.
