SU1708933A1 - Method of aluminium production - Google Patents

Abstract

The invention relates to non-ferrous metallurgy, in particular to a method for producing aluminum by the electrolysis of alumina melts. The purpose of the invention is. nor - increase in metal yield over current. This is achieved by the decomposition of alumina at 700-820 '* C in the melt with a density of 0.05-0.4 g / cm ^ higher than the density of aluminum. It is shown that the difference in densities, less than 0.05 g / cm ^, reduces the current output by up to 90%, and exceeding this difference to a value of 0.4 g / cm ^ Ie causes the effect of 1% (current flow in excess of 94%). The method is implemented in big .j; * polar electrolyzers, the end of which is similar to the structures of magnesium - ^ - * "electrical electrodes; shh bath. 2 ill."

Description

This invention relates to the metallurgy of aluminum and may & It has been used in the production of aluminum by the electrolysis of molten alumina-containing electrolytes.

The aim of the invention is to increase the current output of the metal.

The decomposition of alumina is osus1stv from at 700-820 0 in the melt, the density of which is 0.05-0.4 g / cm 3 higher than the density of aluminum. A / O accumulating on the electrolyte surface, when the melt is directed to circulation, sieve cells are collected and prefabricated cells with subsequent periodic or continuous sampling of the metal and alumina loading.

Examples of electrolyte, the density of which is higher than the density of aluminum can serve as the electrolyte composition, wt.%:. 22; CaF 14.2; NaF 20.6; AlF 43.2, having a temperature of 655 and a density of 2.6-2.7 g / cm at a temperature of 700-800 t.

Laboratory experiments have shown that if the density of eeprolit makes the nTtOTHocTb aluminum less than 0, L5 g / cm3, a sharp increase in the current output of aluminum is observed, and its increase of more than 0.4 g / cm does not cause a further increase in current output:

Current output,%

81 90 92 93 94 94 1 A significant decrease in current output with decreasing electrolyte density (0.05 g / cm3 less density than a / g) ii) is caused by settling of aluminum, which leads to soiling of aluminum droplets in the electrolyte, their oxidation and dissolving. When the density of the Electrolyte exceeds the density of aluminum by more than O, g / cm, the current output does not increase further. In Fig. 1, an electrolyzer is shown for implementing an aluminum production method; figure 2 - the same. The electrolyzer consists of an electro ™ lytic bath 1 containing one or more precast cells 2 separated by partitions 3 with channels 4 from the electrochemical cell with two unipolar 5 and a large number of bipolar 6 electrodes in the cell 7. The method is as follows. The aluminum precipitated at the cathode floats together with the vertical flow of exeptrolite resulting from the evolution of gas at the anode. Due to the increase in the level of the melt in the electrochemical cell 7, this electrolyte flow is directed to the upper overflow channel k and then to the collecting cell 2, and along with the drops, alomin drops are carried along. In the assembly cell 2, the droplets settle and the metal accumulates in the upper part. Further, the electrolyte flow is directed to the lower flow channel and then to the electrochemical cell. As accumulation is carried out, periodic sampling of aluminum is carried out. Alumina feed

with. through the assembly cell using a special device. As the anode and anodic parts of the 6p bipolar electrodes are burned, the electrodes are transferred before and after using a special device, the cinder is periodically removed and the vessel is installed and, in order to increase the current output, decomposition of alumina will be melted at 0.05-0, A g / cm3 higher than the density of aluminum, after which it is carried out; equal circulation of the melt with the removal of aluminum into the assembly cell. The 3rd anode. The significant electrolyte convection in the assembly cell contributes to the distribution of alumina along the bath. This eliminates the need for a complex alumina feed system at each interpolar gap. Part of the alumina, which does not have time to dissolve, is deposited at the bottom of the collecting cell and further dissolves, since the surface of the alumina contacts the electrolyte and is hidden by a layer of metal. This eliminates the formation of solid precipitation. The reduction in the share of work in progress is achieved by reducing the area and thickness of the aluminum layer. For example, if a bath has a size of 2 m., Then with a thickness of an aluminum layer of 0.3 m there is 3} 75 mz of liquid alomina. Even if . the total width of the prefabricated cells will be 1 m, then at the same thickness of the aluminum layer and the length of the bath the amount of aluminum will be 1.5, m, which is more than 1 times less than the prototype. With the upper collection of aluminum, the thickness of its layer can be significantly reduced, and the width of the prefabricated cells can be reduced, which will further reduce the amount of aluminum permanently in the bath. of the invention. The method for producing aluminum, which includes electrochemical decomposition in a low-melting electrolyte at a temperature of alumina charged to the melt 700-820 0, distinguishes V

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Claims (1)

Claim A method of producing aluminum, including electrochemical decomposition in a low-melting electrolyte at a temperature of alumina loaded into the melt of 700-820 ° C, characterized in that, in order to increase the current efficiency, the decomposition of alumina is introduced into the melt with a density of 0.05- 0.4 g / cm ³ higher than the density of aluminum, and then carry out directional circulation of the melt with the removal of aluminum in the collection cell. Figure 1