A kind of aluminum electrolysis method using aluminum as cathode

Abstract

The invention discloses an aluminum electrolysis method with aluminum as a cathode, and relates to the improvement on a method for producing electrolysis aluminum through a molten-salt method. The aluminum electrolysis method is characterized in that in the aluminum electrolysis process, molten aluminum at the bottom of an electrolysis cell is adopted as the cathode for conducting aluminum electrolysis; and the molten aluminum at the bottom of the electrolysis cell makes contact with a cathode busbar to form the aluminum electrolysis cathode. According to the aluminum electrolysis method with the aluminum as the cathode, a conventional anode system, a discharging system and a dust purifying system can be adopted in the aluminum electrolysis cell. According to the method, the molten aluminum in which no cathode carbon block, no steel bar and no titanium boride coating exist is adopted as the cathode to replace a cathode composed of steel bars and a carbon block set. The defects that according to a traditional aluminum electrolysis cell, aluminum oxide deposit exists on cathode carbon blocks and cellular micro-batteries exist are eliminated. In the electrolysis production process, the problem that aluminum oxide and aluminum carbide which are deposited and generated at the furnace bottom pollute electrolysis molten aluminum does not exist.

Description

technical field [0001] An aluminum electrolysis method using aluminum as a cathode relates to the improvement of the aluminum electrolysis method produced by molten salt method. Background technique [0002] At present, conventional electrolytic aluminum production uses cryolite-alumina melt as the electrolyte, carbon as the anode, and a cathode system composed of liquid aluminum, cathode carbon block, and cathode steel rod as the cathode, and a direct current is applied to precipitate CO at the anode. 2 Gas, and liquid aluminum is precipitated at the cathode. The schematic diagram of the traditional aluminum electrolytic cell is shown in figure 1 . According to the current technology, the production of 1 ton of metal aluminum needs to consume about 15,000kw h of integrated alternating current. Under the process conditions of aluminum electrolysis at 930-960°C, the energy utilization efficiency of aluminum electrolysis is less than 36% (anode carbon material consumption is ...

AI Technical Summary

Problems solved by technology

According to the current technology, the production of 1 ton of metal aluminum needs to consume about 15,000kw h of integrated alternating current. Under the process conditions of aluminum electrolysis at 930-960°C, the energy utilization efficiency of aluminum electrolysis is less than 36% (consumption of anode carbon material is equivalent to power consumption 3000kw·h)

On the cathode carbon block of the traditional electrolytic cell, it is easy to form alumina precipitation. The honeycomb precipitation formed on the carbon block cathode of the traditional aluminum electrolysis cell, and the alumina precipitation formed on the cathode carbon block are affected by the cold and hot state of the electrolytic cell. The precipitation can be in the form of paste, shell or honeycomb. Paste or shell-like precipitation can increase the cell voltage by 400mv-900mv. Honeycomb precipitation not only increases the pressure drop at the bottom of the cathode furnace, but also forms a In the micro-battery with the cathode carbon block as the cathode, alumina is generated on the anode of the micro-battery, aluminum carbide is generated on the cathode, and the alumina precipitated on the cathode of the carbon block increases the power consumption of electrolytic aluminum and reduces the current efficiency of aluminum electrolysis. The generated alumina and aluminum carbide cause the pollution of the electrolytic aluminum liquid. The schematic diagram of the honeycomb precipitate formed on the carbon cathode of the traditional aluminum electrolytic cell is shown in Figure 4

[0003] To sum up, in an aluminum electrolytic cell with a traditional structure whose cathode is composed of molten aluminum and cathode carbon blocks, the voltage drop of the cathode steel rod accounts for about 49% of the voltage drop at the bottom of the furnace, which greatly increases the power consumption of aluminum electrolysis; During the use of the tank, the infiltrated electrolyte forms a non-conductive solid electrolyte layer 2g at the carbon-steel contact part, which causes a sharp increase in the carbon-steel contact pressure drop and increases the power consumption of aluminum electrolysis; the oxidation formed on the cathode carbon block Aluminum precipitation not only increases the pressure drop at the bottom of the cathode furnace, but also forms a micro-battery with aluminum as the anode and cathode carbon block as the cathode. The resulting alumina and aluminum carbide increase the power consumption of electrolytic aluminum and reduce the current efficiency of aluminum electrolysis , At the same time cause electrolytic aluminum pollution

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