D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:

V. A. Brodskiy, Senior Researcher, Candidate of Сhemical Sciences, e-mail: vladimir_brodsky@mail.ru
Yu. O. Malkova, Lead Engineer, e-mail: jui77_77@mail.ru
D. Yu. Zhukov, Advisor to Rector, Candidate of Technical Sciences, Associated Rrofessor, e-mail: dmzhukov@muctr.ru
V. A. Kolesnikov, Head of the Department of Inorganic Matter and Electrochemical Processes, Doctor of Technical Sciences, Professor, e-mail: tnv-i-ep@yandex.ru

This paper looks at how the solubility, dispersion ability and charge (-potential) of particles contained in poorly soluble compounds of non-ferrous and rare earth metals influence their recovery from aqueous solutions as part of three-component systems by electroflotation and filtration. The paper describes a case study of hydroxides of aluminium (III), cerium (III), zinc (II) and lead (II). It is demonstrated that the poorly soluble lead compounds can only be recovered from aqueous solutions together with poorly soluble compounds of accompanying metals. At the same time, the high flotation activity of Pb (II) within the entire pH range is attributed to the sorption of Pb (II) ions and disperse phase on the disperse phase of poorly soluble compounds of Al (III), Сe (III) and Zn (II). It is noted that a synergistic effect is observed during the recovery of the disperse phase of the system Ce (III) – Zn (II) – Pb (II). It stands for a fuller and more efficient co-recovery of metals and may be linked to neutralized negative charge of the poorly soluble compounds of Ce (III). The size of the disperse phase in the studied systems tends to average out compared with the one in separate compounds. The size of the disperse phase reaches 30 μm for the system Ce (III) – Zn (II) – Pb (II) and 36 μm for the system Al (III) – Zn (II) – Pb (II). Similar averaging occurs to the electrokinetic potential of the disperse phase, which for the studied threecomponent systems lies in the range of –4…–9 mV. The conducted study helped identify the pH level associated with the maximum possible removal of metal ions as part of multicomponent systems from water: 8.0 for the system Al (III) – Zn (II) – Pb (II); 10.0 for the system Ce (III) – Zn (II) – Pb (II). In this pH range, the electroflotation recovery for all the components reaches 93–98%. Through further filtration, the recovery can be raised to 99% and more.
This research was funded by the Ministry of Education and Science of the Russian Federation under the Grant Agreement No. 14.583.21.0068 dated 22 November 2017. The project’s unique identifier: RFMEFI58317X0068.

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