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RU-2861645-C2 - ELECTROLYTIC CELL FOR PRODUCING ALUMINIUM FROM ALUMINA

RU2861645C2RU 2861645 C2RU2861645 C2RU 2861645C2RU-2861645-C2

Abstract

FIELD: non-ferrous metallurgy. SUBSTANCE: electrolytic cell for producing aluminium from alumina comprises a vertically oriented metal cell with a bottom part, in which a drain pipe for draining primary aluminium is placed, and which is surrounded on the outer surface by wall heating elements along its height, externally closed by a heat-insulating filler, a lid on the upper part of the cell for pouring alumina into the cell cavity, and a pipe for discharging a gaseous product from the cell cavity, as well as a low-consumption bipolar electrode neutral to alumina with a constant interelectrode distance between the cathode and the anode, under which a cavity in the cell, connected to the drain pipe, is arranged for receiving primary aluminium flowing down the cathode. The cathode is made in the form of a metal tube placed in the cell adjacent to the side wall of the cell. The anode is made in the form of a metal tube located inside the cathode equidistantly to the inner surface of the side wall of the cathode. The end surfaces of said cathode and anode tubes in the bottom area of the cell are located in a common horizontal plane above the cavity for receiving primary aluminium flowing down the cathode. The end surfaces of said cathode and anode tubes are located in the lid area in a common horizontal plane passing under the lid to form a cavity between the lid and the electrode, filled with an electrolyte melt. The lid is configured to pour alumina into the cavity between the walls of the cathode and the anode. EFFECT: simplifying the design of the electrolytic cell. 6 cl, 1 dwg

Inventors

  • ANISIMOV Oleg
  • ANISIMOV Dmitrij

Dates

Publication Date
20260506
Application Date
20240809

Claims (6)

  1. 1. An electrolysis bath for producing aluminum from alumina, comprising a vertically oriented metal bath with a bottom part in which a drain pipe for draining primary aluminum is placed and which is covered along the outer surface by heating elements of the bath wall along its height, covered on the outside with a heat-insulating filler, a cover on the upper part of the bath for filling the cavity of the bath with alumina and a pipe for removing the gas product from the cavity of the bath, as well as a low-consumption, alumina-neutral bipolar electrode with a constant interelectrode distance between the cathode and the anode, under which a cavity is organized in the bath, communicated with the drain pipe, for receiving primary aluminum flowing down the cathode, characterized in that the cathode is made in the form of a metal pipe placed in the bath adjacent to the side wall of the bath, and the anode is made in the form of a metal pipe located inside the cathode equidistant from the inner surface of the side wall of the cathode, wherein the end surfaces of the said cathode pipes and the anode in the area of the bottom of the bath are located in a common horizontal plane above the cavity for receiving primary aluminum flowing down the cathode, the end surfaces of the said tubes of the cathode and anode are located in the area of the cover in a common horizontal plane passing under the cover to form a cavity between the cover and the electrode filled with molten electrolyte, and the cover is designed with the possibility of filling alumina into the cavity between the walls of the cathode and the anode.
  2. 2. A bath according to item 1, characterized in that a burner unit operating on natural fuel is located under the bottom part.
  3. 3. The bath according to item 1, characterized in that the cathode is made of titanium.
  4. 4. The bath according to item 1, characterized in that the cathode is made of a titanium-containing alloy.
  5. 5. The bath according to item 1, characterized in that the cathode tube is adjacent to the side wall of the bath through a lining layer.
  6. 6. A bath according to item 1, characterized in that the interelectrode distance is selected in the range of 2-10 cm.

Description

The invention relates to non-ferrous metallurgy, in particular to the electrolytic production of aluminum, namely to the design of an electrolyzer for the production of primary aluminum with bipolar electrodes and reduced energy consumption. In recent years, a clear trend has emerged toward the use of electrolyzers with bipolar electrodes. This has been facilitated by the widespread adoption of low-wear anodes and diaphragms with extended service life. Electrolyzers with bipolar electrodes are more compact and allow for space savings. Their manufacture requires fewer construction materials. They are also easier to maintain during operation, as they have a limited number of control and adjustment points. The abandonment of the carbon anode and the transition to a non-consumable (low-consumption) metal or other electrically conductive bipolar electrode, resistant to cryolite-alumina melt, solves the environmental problems of the process, replacing the emission of greenhouse gases CO and CO2 into the atmosphere with oxygen released at the anode during the decomposition of alumina. The studies were conducted using a standard carbon electrolytic cell with baked anodes and electrolysis cell dimensions of 9870 mm by 4620 mm and a current of 190 kA. The cell contains 24 carbon blocks arranged in two rows of 12 carbon blocks per row. The carbon block dimensions in plan are 1600 mm by 700 mm. The working area of a single carbon block is 1,120,000 mm² . To maintain the initial conditions of the electrolytic process with a single carbon block, we calculate the equivalent required working area of an assembly of neutral, bipolar, coaxial electrodes. Let us take as initial the maximum values of the dimensions of the bipolar, coaxial electrodes, which allow us to remain within the dimensions of one carbon block with dimensions of 1600 mm by 700 mm in plan with the same working area equal to 1,120,000 mm 2. Since the width of the replaceable carbon block is 700 mm, then the diameter of the anode fragment of the bipolar, coaxial electrode is set, taking into account the thickness of the anode fragment of 30 mm, equal to 700 - 60 = 640 mm. With an interelectrode distance (IDE) of 50 mm, the cathode fragment diameter of the electrode is 640 - (50 × 2) = 540 mm with a working area of the cathode of the bipolar coaxial electrode of 670 mm in height: 540 × 3.1 × 670 = 1,121,580 mm 2 , which is greater than that of one entire carbon block (1,120,000 mm 2 ). These calculations show that instead of one carbon block with plan dimensions of 1,600 mm by 700 mm, two neutral, bipolar/coaxial electrodes can be placed within its dimensions. Analysis of the obtained data allows us to draw the following conclusions: replacing the carbon blocks in the 190 KA electrolyzer with neutral, bipolar, coaxial electrodes makes it possible to: 1. Double the productivity of the electrolyzer by replacing each carbon block in the electrolyzer with two inert, bipolar, coaxial electrodes of the same dimensions. 2. To fundamentally solve the modern environmental problem of aluminum production by electrolysis, by eliminating the emission of greenhouse gases CO and CO2 , replacing them with the emission of O2 oxygen. 3. Simplify the electrolyzer control algorithm at a constant MER (interelectrode distance) by excluding anode mechanisms from the control circuit. Replacing carbon anodes with neutral ones increases energy consumption to compensate for the missing heat generated by the carbon anodes. For this purpose, non-electric energy sources can be used to melt and maintain the electrolyte in a liquid state during the electrolysis process. This enables energy savings of up to 47% and is expressed by the formula Wc + Wg = Wp + We + Wm, where Wc is the total energy supplied to the electrolyzer, Wg is the energy released during the combustion of the carbon anodes; We is the energy spent on the electrolytic process itself; We is the energy lost during the draining of the aluminum melt from the electrolyzer. The new technology proposes spending electricity only on the electrolytic process of alumina decomposition, i.e. We, and Wg + Wp + Wm is compensated by the combustion of organic fuel. This makes it possible to save up to 47% of electricity, and the formula for the process looks like this: Welectro = Weelectrolysis Worg = Wemelt + Wmet, where Welectro is the consumed electricity, and Worg is the combustion energy of organic fuel. Thus, a device for the electrolysis of aluminum oxides in aluminum melts is known, which includes a vertically oriented cylindrical bath, on the inner wall of which a lining is organized, a bottom part made in a glass shape with a flange on the open edge for connection with the lower part of the housing and a hollow bottom, the cavity of which is communicated with a channel for supplying gaseous nitrogen, and on the upper bottom wall of which a ceramic filter is placed for passing the said nitrogen through the cracks, a cover for fasten