Siberian Federal University, Krasnoyarsk, Russia

N. V. Vasyunina, Associate Professor of the Department of Metallurgy of Non-Ferrous Metals, Institute of Non-Ferrous Metals, Candidate of Technical Sciences, e-mail: nvvasyunina@yandex.ru
I. V. Dubova, Associate Professor of the Department of Fundamental Natural Science Education, Institute of Non-Ferrous Metals, Candidate of Technical Sciences, e-mail: idubova@mail.ru

T. R. Gilmanshina, Associate Professor of the Department of Technosphere Safety of Mining and Metallurgical Industries, Institute of Non-Ferrous Metals1, Candidate of Technical Sciences, e-mail: gtr1977@gmail.com

LLC Indust-PRO, Krasnoyarsk, Russia.
K. E. Druzhinin, Deputy Director, e-mail: Bearget@mail.ru

The article analyzes the possibility of using electrodialysis for processing weak aluminate solutions (sludge water) of alumina production for the purpose of their concentration and causticization. The studies were carried out using the example of sludge water taken at the outlet of the gas cleaning installation of the sintering furnace of JSC RUSAL Achinsk. To carry out the tests, the authors used a threechamber electrodialysis cell with heterogeneous cation exchange membranes MK-40; titanium alloy VT1-0 was used as the cathode and anode materials. Electrodialysis was carried out at an interpolar distance of 3–5 cm and a current density of 0.5–3.0 A/dm2 to produce cathode (more concentrated caustic alkali solution) and anodic solutions (desalinated solution), as well as anode sludge (presented mainly in aluminum hydroxide). The authors calculated the change in the activation energy of specific electrical conductivity. It has been shown that the process of charge transfer in the studied range of concentrations and temperatures is limited by diffusion restrictions. The optimal operating parameters have been selected for the process of electrodialysis concentration of an aluminate solution: current density is about 2 A/dm2 at an interpolar distance of 4 cm. At these operating conditions parameters, operating voltage on the cell achieves 24 V after 40–45 minutes, while the specific energy consumption increases from 13.5 to 17.5 kWh/kg of alkali. It has been determined that the soda content in the solution within an hour decreases from 55 to 25–30% of total alkalinity at various operating parameters of the electrodialysis process. The degree of concentration of total alkali in the solution at the selected process parameters after an hour from the start of electrodialysis reaches 1.40–1.45.

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