Siberian Federal University, Krasnoyarsk, Russia:

R. B. Magerramov, Postgraduate Student at the Department of Non-Ferrous Metallurgy, e-mail: rusmahar9313@gmail.com
N. V. Belousova, Head of the Department of Non-Ferrous Metallurgy
S. G. Shakhray, Associate Professor at the Department of Mining and Metal lurgical Safety

RUSAL, Krasnoyarsk, Russia:
A. V. Malyshkin, Site Manager, Fluorides Production and Dust-Arresting Equipment

This paper describes the results of the first stage of laboratory tests carried out for the process of sodium fluoride adsorption from slime waters and scrubbing solutions using smelter grade alumina. This process can produce fluoride rich alumina, which can be dried and used in aluminium electrolysis processes thus saving fresh cryolite and aluminium fluoride. The tests showed that the maximum recovery of sodium fluoride from scrubbing solutions was 92% when the mixing time (solutions with alumina) was 45 min.; from slime waters — 87% even during the first minute of the experiment. Simultaneous adsorption of sodium sulphate was observed with the recovery of 31% from scrubbing solutions and 13% from slime waters. Moreover, it was found that when extracting sodium fluoride from slime waters and scrubbing solutions the optimum mixing time (contact with alumina) should not exceed 3 min. as in this case the recovery of sodium sulphate is minimal (18–19%). Due to a stable chemical composition and a more efficient recovery of sodium fluoride, the use of slime water appears to offer a better solution for the adsorption process. Thus, scrubbing solutions purified in this manner can be used for recovery of sodium sulphate, while slime waters can be used in the production of scrubbing solutions, which would help save fresh water required for this process.

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