Electrode structure for combined production and electrolysis of oxygen and aluminum
Technical Field
The invention belongs to a wettable electrode structure for oxygen-aluminum co-production electrolysis or carbon-free aluminum electrolysis, and particularly relates to an electrode structure for so-called 'inertia' or 'wettability'.
Background
The prior Hall-Herout aluminum electrolytic cell adopts a consumable carbon anode, not only consumes a large amount of carbon materials which take high-quality petroleum coke as a main body, but also discharges a large amount of greenhouse effect gas CO2Strong greenhouse gas fluorocarbons(CF4、C2F6)、SO2In addition, in the existing aluminum electrolysis process, the prebaked anode carbon block needs to be continuously replaced frequently, so that the electrolysis production is unstable, the labor intensity, the personal risk of workers facing high-temperature melt and the inorganized emission of fluoride are increased; carcinogenic aromatic compounds (PAH) and SO are also discharged in the production process of the prebaked carbon anode2Dust, which are one of the main sources of PM 2.5; in addition, the adoption of the carbon anode is also the main reason of the problems of high energy consumption, high cost and the like of the existing aluminum electrolysis process.
The new process for realizing the co-production electrolysis of oxygen and primary aluminum by adopting a non-carbon anode or an inert anode can solve the problems of emission and pollution, improve the production efficiency, reduce the occupied area and reduce the production cost, and becomes a focus of attention and a research hotspot in the international aluminum industry and the material industry. The non-carbon anode used in the combined electrolysis process of oxygen and aluminum has the following advantages: (1) the electrode is hardly consumed in the electrolytic process, the material consumption is less than one percent of that of the carbon anode, and an attached carbon processing factory and a carbon anode assembly factory are not needed, so that the production cost is reduced, and the environmental influence and pollution caused by the production and use of the carbon anode are eliminated; (2) the electrode is not consumed, the polar distance is stable, the control is easy, the anode replacement frequency is reduced by more than ten times, and the labor intensity and the occupational risk are greatly reduced; (3) the higher current per unit volume can be adopted, so that the productivity of the electrolytic cell is increased; (4) the anode product is oxygen, which avoids environmental pollution, and the oxygen can also be used as a byproduct.
To realize the series of advantages of the non-carbon anode, the traditional horizontal arrangement mode of the electrodes can not be adopted, but the vertical arrangement mode of the electrodes is adopted, so that the heat balance can be well maintained, the cell voltage is reduced, and the energy consumption is reduced. Thus, the vertical mounting method of the wettable cathode plays an important role in realizing the carbon-free aluminum electrolysis technology.
Patent US 2017/0283968Al describes the method of attachment of the vertical cathode but does not take into account thermal expansion, expansion caused by sodium potassium penetration which would seriously affect the stability and life of the vertical cathode and further does not describe how the slits in the cathode support block are treated.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a method for installing, preventing and eliminating swelling of a vertical wettable cathode block or an inverted hollow cup-shaped cathode for combined electrolysis of aluminum oxide so as to prolong the service life of the cathode block.
The aluminum electrolysis cell consists of a hearth of the electrolysis cell, a cathode conductive base, an aluminum water tank and high-temperature molten salt, wherein the vertical non-carbon anodes and the vertical cathodes are oppositely arranged in parallel, and the anodes and the cathodes can be continuously arranged at intervals until the required capacity is reached.
The high-temperature molten salt is NaF-KF-CaF at the temperature of 750-2-MgF2-LiF-AlF3-Al2O3And (4) melting the melt.
The electrode structure for combined production and electrolysis of oxygen and aluminum comprises an anode group, a cathode group and a cathode conductive base, wherein the anode group and the cathode group are vertically, parallelly and oppositely arranged, and the cathode is in a plate shape, a block shape or a cuboid deep cup shape and is arranged on the cathode conductive base at the bottom of an electrolytic cell.
Further, the cathode support base is arranged in a groove or a groove on the cathode conductive base, a filler is arranged between the cathode support base and the cathode conductive base, and the material of the cathode support base is TiB2Base material, graphite base material, carbon material and TiB on surface2The base coating is one of a graphite-based material or a carbon material.
The cathode conductive base material is graphite-based material, carbon material or TiB2-one of C composite materials; the cathode conductive base is provided with grooves or slots for supporting the vertical cathode, has conductivity, and transfers the current from the anode to the cathode through the electrolyte, and then to the current collector iron bar or steel bar or alloy bar inside or below the cathode to the cathode bus.
The cathode is made of TiB2The cathode is in a plate-shaped or block-shaped structure, the periphery of the cathode is a chamfer or the long edge of the cathode is a straight edge, the two sides of the cathode are circular arcs, and the cathode is directly inserted into a groove or a slot on the cathode conductive base during installation or is embedded in the cathode firstlyThe supporting base is inserted into the groove on the cathode conductive base; and a filler is arranged between the cathode and the cathode supporting base; the filler is graphite fiber, carbon cloth, carbon paper, SiC fiber, TiB2One or more of the fibers are combined and woven or pressed.
The cathode is made of TiB2And the cathode is in a cuboid deep cup shape, the periphery of the cathode is a chamfer angle or the long edge of the cathode is a straight edge, the two sides of the cathode are circular arcs, the cathode is connected with the battery cell during installation, the battery cell is inversely inserted into the deep cup, and then the battery cell is inserted into the groove or the groove of the cathode conductive base.
The electric core is TiB2Base material, graphite base material, carbon material and TiB on surface2The base coating is made of one of graphite-based material or carbon material, and a filler is arranged between the battery core and the deep cup-shaped cathode material.
The filler is graphite fiber, carbon cloth, carbon paper, SiC fiber, TiB2One or more of the fibers are woven or pressed in combination with the filler as a buffer layer to adjust the verticality while preventing thermal expansion at high temperatures from crushing the cathode material itself or the cathode substrate to maintain the stability of the vertical cathode.
Furthermore, an insulating pressing strip is arranged between the horizontal plane of the aluminum liquid and the cathode conductive base to further stabilize the cathode and keep the verticality of the cathode, and the insulating pressing strip is made of amorphous high-alumina material or made of alumina ceramic, SiC ceramic and Si3N4Ceramics, BN-TiB2One or a composite of the composite ceramics.
Further, the surface of the cathode conductive base is coated with a coating which is high alumina cement and TiB2Base coating, SiC coating, Si3N4One or more than two composite coatings in the coating. The aim is to reduce the sodium and potassium expansion caused by the permeation of Na and K in the electrolyte to the cathode conductive base.
Furthermore, a cathode steel bar current collector is arranged below the cathode conductive base.
Drawings
FIG. 1 is a schematic diagram of an arrangement of vertical anodes and vertical cathodes;
FIG. 2 shows a block or plate (a), deep cup (b) TiB2A base cathode material;
FIG. 3 is a schematic view showing the shape and installation of a coreless vertical cathode of example 1;
fig. 4 is a schematic view of the cell-containing vertical cathode shape and installation in example 2;
FIG. 5 is a schematic view of the coreless vertical cathode shape and installation of example 3;
FIG. 6 is a schematic view of the coreless vertical cathode plate and installation of example 4;
FIG. 7 is a schematic view of the shape and installation of two vertical cathodes without electric core in example 5;
description of reference numerals: 1-inert anode, 2-wettability inert cathode, 3-battery core, 4-filler, 5-insulating layering, 6-coating, 7-cathode conductive base, 8-cathode steel bar current collector and 9-cathode supporting base.
Detailed Description
The technical scheme of the invention is further explained by the figures and the specific embodiments of the specification.
Example 1
One of the shapes and mounting methods of the vertical cathode: a coreless vertical cathode shape and method of installation as shown in figure 3.
The anode group and the cathode group are vertically and parallelly arranged oppositely, the cathode is of a plate-shaped or block-shaped integrated structure, the cathode is directly inserted into a groove or a groove on the cathode conductive base during installation, an insulating pressing strip is further arranged between the horizontal plane of aluminum liquid and the cathode conductive base, the surface of the cathode conductive base is coated with a coating, and a cathode steel bar current collector is arranged below the cathode conductive base.
Example 2
One of the shapes and mounting methods of the vertical cathode: a cell vertical cathode shape and method of installation as shown in figure 4.
The anode group and the cathode group are vertically and parallelly arranged oppositely, the cathode is in a cuboid deep cup shape, the cathode is connected with the battery cell during installation and inversely inserted into the deep cup, then the battery cell is inserted into the cathode conductive base groove or the slot, a filler is arranged between the battery cell and the deep cup-shaped cathode material, an insulating depression bar is further arranged between the horizontal plane of the aluminum liquid and the cathode conductive base, and a cathode steel bar current collector is arranged below the cathode conductive base. Example 3
One of the shapes and mounting methods of the vertical cathode: another configuration and mounting method for a coreless vertical cathode is shown in fig. 5. In order to prevent thermal expansion and fix the vertical cathode, the cathode is sleeved with a filler, the cathode plate is pushed into a strip seam reserved on the cathode base in an extrusion mode, the cathode is kept vertical, and the filler is woven by carbon fibers or is made into a bag shape by one or more layers of carbon cloth or carbon paper. For supporting the cathode plate, an insulating pressing strip is adopted for supporting and positioning, and the insulating pressing strip is made of high alumina ceramic, high alumina amorphous material casting, SiC ceramic and Si3N4One of the ceramics is prefabricated. In order to prevent the expansion of sodium and potassium, a coating is coated on the upper surface of the cathode base to reduce the permeation of sodium and potassium to the base, and the coating can be SiC, high alumina cement, Si3N4、TiB2-one of C composite coating.
Example 4
One of the shapes and mounting methods of the vertical cathode: another configuration and mounting method for a coreless vertical cathode is shown in fig. 6. In order to prevent thermal expansion and fix the vertical cathode, the cathode is sleeved with a filler, the cathode plate is pushed into a strip seam reserved on the cathode conductive base in an extrusion mode, the cathode is kept vertical, and the filler is woven by carbon fibers or is made into a bag shape by one or more layers of carbon cloth or carbon paper. In order to prevent the expansion of sodium and potassium, a coating is coated on the upper surface of the cathode base to reduce the permeation of sodium and potassium to the base, and the coating can be SiC, high alumina cement, Si3N4、TiB2-one of C composite coating.
Example 5
One of the shapes and mounting methods of the vertical cathode: a shape and mounting method of two-section coreless vertical cathode, as shown in fig. 7. For preventing thermal expansion and fixing the vertical cathode, the cathode is filled with a filler, and the cathode plate is pushed into the cathode support base in an extrusion mannerIn the long seam, the cathode is kept vertical, and the filler is woven by carbon fiber or made into a bag shape by one or more layers of carbon cloth or carbon paper. The cathode supporting base may be TiB2-C composite material, graphite-based material, carbon material, surface coated with TiB2-C-coated graphite-based or carbon material. The cathode supporting base is pushed into a reserved pit of the cathode conductive base. In order to prevent the expansion of sodium and potassium, a coating is coated on the upper surface of the cathode base to reduce the permeation of sodium and potassium to the base, and the coating can be SiC, high alumina cement, Si3N4、TiB2-one of C composite coating.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.