Patent Application
20240426016
The present application claims a priority of Chinese patent application No. 202310009797.0 filed on Jan. 4, 2023, the entire content of which is incorporated herein by reference.
The present disclosure relates to a technical field of aluminum smelting, and in particular to an inert anode aluminum electrolytic cell with a vertical structure.
In the current context of “carbon peaking and carbon neutrality”, problems of high intensity and large amount of carbon emission caused due to the consumption of carbon anode and anode effect have become increasingly prominent in the process of traditional aluminum electrolytic production with prebaked carbon anode. Inert anode aluminum electrolytic technology, as there is no emission of carbon dioxide and perfluorinated compounds (PFCs) in an electrolytic process and about 0.88 tons of oxygen is produced per ton of aluminum in the electrolytic process, has become an important development and research direction for the technology of the aluminum smelting industry.
At present, an inert anode aluminum electrolytic cells with a vertical electrode structure have become a mainstream research direction. An area of an electrode of the inert anode aluminum electrolytic cell using a vertical electrode arrangement can be greatly increased, thereby reducing a volume of the electrolytic cell, increasing productivity, reducing heat dissipation, and thus making up for the shortcoming of a theoretical decomposition voltage of the inert anode being higher than that of the carbon anode.
The inert anode aluminum electrolytic cell with the vertical electrode arrangement needs to use a cathode material that can be well wetted with an aluminum water, so that the aluminum can smoothly precipitate and gather on a liquid aluminum film formed on a surface of a cathode. Currently, commonly used materials are a TiB2 ceramic, or a TiB2—C composite ceramic with high TiB2 content and so on. These materials with large sizes cannot be easily manufactured due to the limitations of current preparation technology. These materials, when used as a wettable cathode, usually need to be spliced by multiple pieces. At present, there are two commonly used splicing solutions. One splicing solution is that firstly a cathode is connected to a graphite base by a pounded cathode paste, and then a metal guide rod is connected to the graphite base by the pounded cathode paste; the other solution is that firstly a single piece of cathode is connected to a metal guide rod, and then the single-piece cathode and the metal guide rod are combined together with a cathode paste or a corundum castable.
Both of the above solutions have some drawbacks. In the first solution, if a connection of the cathode and the graphite base is achieved only by the pounded cathode paste, the uniformity of conductivity is poor. After the cathode paste is penetrated by an electrolyte melt, the conductivity will be changed greatly, resulting in an uneven distribution of cathode current, and a serious uneven distribution will cause the cathode to rupture and be damaged. In the second solution, it is difficult to protect the metal guide rod from corrosion. The metal guide rod is too close to an electrolytic reaction region of the cathode, thus the metal guide rod is easily corroded directly and electrochemically by the electrolyte melt or the aluminum water penetrating therein, thereby causing the metal guide rod to be damaged, expanded, and broken.
In order to reduce a corrosion rate of the inert anode, a low-temperature electrolyte system is usually used in the inert anode aluminum electrolytic cell. In the low-temperature electrolyte system, KF or LiF is usually contained, a degree of superheat during operating of a low-temperature electrolyte is relatively high, a frozen ledge is not easily formed on a side of an electrolytic cell, and a low-temperature electrolyte melt has strong permeability. Sidewall materials and structures of a conventional electrolytic cell are easily corroded by the electrolyte melt. The electrolyte melt may even penetrate directly from splicing gaps of a furnace to a thermal-insulation layer, thereby destroying a material of the thermal-insulation layer and affecting a life of the electrolytic cell. In addition, as for small-scale electrolytic experiments, external heating is usually required because a quantity of heat generated during an electrolytic process cannot maintain the electrolyte melt at a constant target temperature. If a heating furnace is used for external heating, the size and scale of the electrolytic cell will be limited, and an operation time will be relatively short. If a heating element is arranged inside the furnace, the heating element needs to be replaced repeatedly, or even frequently, and thus a normal operation of the electrolytic cell will be affected.
For example, in a Chinese patent application No. 201710678953.7 and entitled “Inner Heated Molten Salt Electrolytic Cell”, a heating device is attached to an inner wall of the electrolytic cell, and electrolytic tests with 100 A-1000 A can be carried out, but the heating device itself still needs to be replaced regularly. In this patent, the heating element is a single-end electric heating tube and a protective material is a graphite. Although the graphite can withstand a long-term corrosion from the electrolyte melt and the aluminum water, the graphite is easily oxidized. In practical use, the graphite near an interface of the electrolyte melt is oxidized quickly and is easily perforated, and the heating tube is also easily damaged. In particular, in the inert anode aluminum electrolytic test process, oxygen is released and thus an oxidation of the graphite is accelerated, resulting in that the heating device is replaced frequently and a fluctuation range of an electrolyte temperature is large, and the electrolytic experiments sometimes cannot be performed normally. After the heating device is damaged, a temperature drops and the electrolyte solidifies, causing the damaged heating device to be concreted on a side wall of the electrolytic cell, thereby making it impossible to replace the damaged heating device and forcing the electrolytic cell to be shut down.
Existing technical solutions still cannot well solve the problems in a manufacturing process and a stable operation of the inert anode aluminum electrolytic cell with the vertical structure. Therefore, there is still a need for a simple, stable and reliable inert anode aluminum electrolytic cell with a vertical structure.
The purpose of the present disclosure includes, for example, providing an inert anode aluminum electrolytic cell with a vertical structure aiming to solve the above technical problems.
In order to achieve the above object, embodiments of the present disclosure provide an inert anode aluminum electrolytic cell with a vertical structure, comprising: an electrolytic cell shell, provided with three insulating layers therein, the three insulating layers comprises a first insulating layer, a second insulating layer and a third insulating layer, and the first insulating layer and the second insulating layer have both fixed structures, and the first insulating layer is opened with a groove thereon, and an opening of the groove is upward, and the third insulating layer has a replaceable and movable structure; a heating device, disposed in the groove on the first insulating layer, and configured to adjust a temperature of the electrolytic cell; a graphite base, disposed at a bottom of an inner cavity of the electrolytic cell shell, and is opened with a mounting slot at a bottom thereof, and side walls of the second insulation layer and the bottom of the graphite base each are attached to the third insulating layer to form a furnace of the electrolytic cell, and the furnace of the electrolytic cell is configured to contain an electrolyte melt and an aluminum liquid; cathodes, being in a shape of a vertical plate, and vertically mounted in the mounting slot, and threadedly connected to the graphite base through graphite bolts, in which contact surfaces among the graphite base, the graphite bolts and the cathodes are all covered with a cathode paste; one side of the cathodes is provided with anodes, and the anodes are arranged in a staggered manner with the cathodes and is suspended above the electrolytic cell shell by connecting to a guide rod, a current of the anode passes through the guide rod and enters an interior of the electrolytic cell shell from a top of the electrolytic cell, and the cathode current is led out of the electrolytic cell shell through a metal electric rod.
In order to explain the embodiments of the present disclosure or the technical solutions in the prior art more clearly, the accompanying drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings in the following description only illustrate some embodiments of the present disclosure. For those skilled in the art, other accompanying drawings can be obtained based on the structures shown in these accompanying drawings without exerting creative efforts.
Illustration of reference signs: 1, electrolytic cell shell; 2, ceramic fiber plate; 3, dry barrier material layer; 4, first insulating layer; 5, heating device; 6, second insulating layer; 7, third insulating layer; 8, negative graphite rod; 9, thermal insulation cover; 10, thermal insulation sealing layer; 11, guide rod; 12, metal electric rod; 13, graphite base; 14, graphite bolt; 15, cathode paste; 16, cathode; 17, anode; 18, positive graphite rod; 19, anode busbar; 20, coke particle; 21, first metal heating plate; 22, first stainless steel rod; 23, second stainless steel rod; 24, second metal heating plate; 25, third stainless steel rod; 26, fourth stainless steel rod.
The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only some embodiments of the present disclosure, rather than all embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the protection scope sought for by the present disclosure.
It should be noted that all directional indications (such as up, down, left, right, front, back . . . ) in the embodiments of the present disclosure are only used to explain the relative positional relationship, movement conditions and so on among components in a specific posture (as shown in the accompanying drawings), and if the specific posture is changed, the directional indication will also be changed accordingly.
In the present disclosure, unless otherwise explicitly stated and limited, the terms “connect”, “fix” and so on should be understood in a broad sense. For example, the term “fix” may be a fixed connection, a detachable connection, or an integral body; or may be a mechanical connection or an electrical connection, may be a direct connection or an indirect connection through an intermediate medium, or may be an internal communication between two elements or an interactive relationship between two elements, unless otherwise clearly limited. For those skilled in the art, the specific meanings of the above terms in the present application may be understood according to specific circumstances.
In addition, if there are descriptions involving “first”, “second” and so on in the embodiments of the present disclosure, the descriptions of “first”, “second” and so on are for descriptive purposes only and cannot be understood as indicating or implying relative importance of indicated technical features or implicitly indicating the number of indicated technical features. Therefore, features defined as “first” and “second” may explicitly or implicitly include one or more of the described features. In addition, the meaning of “and/or” appearing in the entire text includes three parallel solutions. “A and/or B” is taken as an example, which includes solutions: solution A, or solution B; or a solution that includes both solution A and solution B. In addition, the technical solutions in various embodiments can be combined with one another, but it must be based on the realization by those skilled in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that such a combination of technical solutions does not exist, nor is it within the scope of protection sought by the present disclosure.
As shown in
an electrolytic cell shell 1, within which three insulating layers may be provided; the three insulating layers include a first insulating layer 4, a second insulating layer 6 and a third insulating layer 7; the first insulating layer 4 and the second insulating layer 6 may both be fixed structures, and the first insulating layer 4 may be opened with a groove thereon; an opening of the groove may be upward, and the third insulating layer 7 may be a replaceable and movable structure;
a heating device 5, which may be disposed in the groove on the first insulating layer 4, and configured to adjust a temperature of an electrolytic cell;
a graphite base 13, which may be disposed at a bottom of an inner cavity of the electrolytic cell shell 1. A bottom of the graphite base 13 may be opened with a mounting slot. Side walls of the second insulating layer 6 and the bottom of the graphite base 13 each may be attached to the third insulating layer 7 to form a furnace of the electrolytic cell. The furnace of the electrolytic cell is configured to contain an electrolyte melt and an aluminum liquid;
a cathode 16, which may be in a shape of a vertical plate. The cathode 16 may be mounted vertically in the mounting slot, and may be threadedly connected to the graphite base 13 through graphite bolts 14. Contact surfaces among the graphite base 13, the graphite bolts 14 and the cathode 16 are all covered with a cathode paste 15. One side of the cathode 16 may be provided with the anode 17, and the anode 17 and the cathodes 16 are staggered and the anode 17 may be suspended above the electrolytic cell shell 1 by connecting to a guide rod 11. A current of the anode 17 passes through the guide rod 11 and enters an interior of the electrolytic cell shell 1 from a top of the electrolytic cell. A current of the cathode 16 passes through the graphite base 13 and is led out of the electrolytic cell shell 1 through a metal electric rod 12 connected to the graphite base 13.
In some embodiments, the electrolytic cell shell 1 may be provided with three insulating layers therein. The three insulating layers may include from an inside to an outside in sequence: a replaceable third insulating layer 7 made of a dense corundum material; a second insulating layer 6 made of the dense corundum material; and a first insulating layer 4 made of a corundum castable material. The first insulating layer 4 may be provided with a groove with an opening upward, and a heating device 5 may be mounted in the groove to adjust a temperature in the electrolytic cell. The third insulating layer 7 may include two arc-shaped dense corundum sheets that can be replaced at any time. The second insulating layer 6 may be a complete dense corundum crucible. The graphite base 13 may be placed at a bottom of the corundum crucible, and the metal electric rod 12 passes through a hole reserved on the corundum crucible and may be threadedly connected to the graphite base 13. The second insulating layer 6 made of the dense corundum material may be wrapped by the first insulating layer 4 formed by pouring the corundum castable, to form a circular furnace of the electrolytic cell without splicing gaps for containing the electrolyte melt, an aluminum liquid and to serve as a working region for an inert anode 17 and a wettable cathode 16. Net dimensions of an interior of a furnace may be: 300 mm in diameter and 500 mm in depth. The cathode 16 may be a wettable cathode with a structure of vertical plate. The cathode 16 may be embedded into a mounting slot of the graphite base 13 at a bottom of the electrolytic cell shell 1. The cathode 16 and the graphite base 13 may be connected together with the graphite bolts 14, and surrounding gaps and pits may be filled to be flat with a pounded cathode paste 15. A current of the cathode 16 passes through the graphite base 13 and is led out of the electrolytic cell by the metal electric rod 12 connected to the graphite base 13. The inert anode 17 may be in a shape of vertical plate and arranged in a staggered manner with the cathodes 16, and may be suspended above the electrolytic cell through the guide rod 11. The current of the anode 17 flows through the anode busbar 19 and the guide rod 11, and enters into the electrolytic cell from a top of the electrolytic cell. A thermal insulation sealing layer 10 at a mouth of the furnace of the electrolytic cell may also be a protective layer for the guide rod of the anode, and the protective layer may be made of the corundum castable.
In some embodiments, the heating device 5 may use a direct current for heating, and be disposed with a heat generation element therein. The heat generation element may be coke particles 20, or a first metal heating plate 21 or a second metal heating plate 24.
In some embodiments, the coke particles 20 may include one or more of petroleum coke particles, graphite particles, and a graphite powder. The coke particles 20 may be inserted with a negative graphite rod 8 and a positive graphite rod 18 therein. The negative electrode graphite rod 8 is configured to export a direct current, and the positive electrode graphite rod 18 is configured to import the direct current.
In some embodiments, the coke particles 20 may be contained in the groove in the first insulating layer 4. The negative electrode graphite rod 8 and the positive electrode graphite rod 18 may be inserted into the coke particles 20 as a negative electrode and a positive electrode respectively for passing a direct current through the coke particles 20. The coke particles 20 may include 50% petroleum coke particles with a particle size of 1-3 mm, 45% graphite particles with a particle size of 1-3 mm, and 5% graphite powder. The heating element may be coke particles 20 or the first metal heating plate 21 or the second metal heating plate 24, and a direct current is adopted for heating, and therefore a structure of the heating element is simple and a performance of the heating element is stable. Even if a small amount of electrolyte melt penetrates into an insulating side wall, the heating element is not easily damaged. When the coke particles 20 are used, the coke particles 20 will not be affected by a corrosive effect of the electrolyte, and therefore a conductivity and a heat generation of the coke particles 20 are basically not affected. When the first metal heating plate 21 or the second metal heating plate 24 is used, a filled alumina may make a small amount of the electrolyte melt penetrated within the insulating side wall to be a semi-solidified state, and therefore a conductivity and a heat generation of the first metal heating plate 21 or the second metal heating plate 24 are not affected. In addition, characteristics of heating by the direct current, such as low voltage, high current, and a required low resistance of the heat generation element, make a size of the first metal heating plate 21 or the second metal heating plate 24 able to be made larger, so that an ability to resist oxidation and an ability to resist corrosion are also relatively strong. Therefore, the present disclosure can ensure that a temperature of the electrolytic cell is stable, the electrolyte will not solidify, and the side wall of the third insulating layer 7 will not become concreted thereby facilitating replacement. The stability, operability, and lifespan of the electrolytic cell have been greatly improved.
In some embodiments, a thermal insulation cover 9 is disposed at the groove of the first insulating layer 4, and the thermal insulation cover 9 is configured to reduce an oxidation and burning loss of the coke particles 20.
In some embodiments, when the electrolytic cell reaches a target temperature and remains stable at the target temperature, a DC current of layers of the coke particles 20 is 1.2 kA and a voltage of layers of the coke particles 20 is 4 V-5 V. When the voltage of layers of the coke particles 20 is greater than 5V, it is indicated that there is a burning and loss to the coke particles 20, thus it is required to remove the thermal insulation cover 9 and replenish and press the coke particles 20 with a tool, as long as the voltage of layers of the coke particles 20 is restored to be below 5 V. When a heating power needs to be changed, it may be achieved by adjusting a size of the DC current.
In some embodiments, a material of the first metal heating plate 21 or the second metal heating plate 24 may be one of 310S stainless steel, Aludirome, Monel, and Inconel alloy. The first metal heating plate 21 or the second metal heating plate 24 may be filled with an industrial alumina or a corundum sand therein to reduce an oxidation of the first metal heating plate 21 or the second metal heating plate 24 in a heating process with the direct current passing therethrough.
In some embodiments, the cathode 16 may adopt a TiB2—C composite hot-pressed ceramic, and a content of mass percentage of TiB2 may be ≥60%.
In some embodiments, the first insulating layer 4 may be integrally formed by pouring the corundum castable. The second insulating layer 6 may be made of a material that is resistant to oxidation and electrolyte corrosion. A material of the second insulating layer 6 may be one of a NiFe2O4 ceramic, a NiFe2O4—NiO ceramic, a dense corundum, a boron nitride ceramic, an aluminum nitride ceramic, a silicon nitride ceramic, a silicon carbide ceramic, and a ceramic formed by combining the silicon carbide with the silicon nitride. The third insulating layer 7 may be made of the dense corundum material.
In some embodiments, referring to
In some embodiments, a first anti-seepage thermal-insulation layer is provided outside the three insulating layers within the electrolytic cell shell 1. The first anti-seepage thermal-insulation layer includes from an inside to an outside in sequence: a dry barrier material layer 3, a ceramic fiber plate 2, and a steel cell shell.
In some embodiments, a second anti-seepage thermal-insulation layer may be provided under the graphite base 13 at a bottom of an interior of the electrolytic cell shell 1. The second anti-seepage thermal-insulation layer may include from the inside to the outside in sequence: the corundum castable, the dry barrier material layer 3, the ceramic fiber plate 2, and the steel cell shell.
In some embodiments, the insulating side wall of the electrolytic cell may be disposed in three layers. The side wall of the third insulating layer 7 may be made of the dense corundum material so that the electrolyte will not be polluted and the side wall of the third insulating layer may be a replaceable buffer layer. The replaceable buffer layer can be a first physical protection for the side wall of the second insulating layer 6 to avoid the electrolyte melt from directly scouring the side wall of the second insulating layer 6. The side wall of the second insulating layer 6 may be made of a material that is resistant to oxidation and electrolyte melt corrosion. The first insulating layer 4 may be integrally cast by using the corundum castable to wrap the side wall of the second insulating layer 6 and the graphite base 13 at a bottom of the electrolytic cell shell 1 into a whole without splicing gaps. A temperature of the insulating side wall gradually decreases from an inside to an outside and the dry barrier material layer 3 is combined, and therefore the electrolyte melt can be effectively prevented from leaking to a thermal-insulation layer at outside, thereby greatly extending a life of the electrolytic cell.
In addition, since side walls of the first insulating layer 4 may be made of the corundum castable, so that a size of the electrolytic cell is not limited and thus may be suitable for requirements for the electrolytic cells of different scales. For example, the requirements of the electrolytic cell as small as tens of amps to thousands of amps in laboratories, and the requirements of electrolytic cells as large as tens of thousands of amps to hundreds of thousands of amps in industrial tests can be met.
According to the inert anode aluminum electrolytic cell with the vertical structure provided by some embodiments of the present disclosure, in the present disclosure relevant electrolytic tests are conducted. The following are relevant processes of the electrolytic tests and the electrolytic tests have achieved at least the following effectiveness.
Referring to
A three-layer insulating side wall of the electrolytic cell may include from the inside to the outside in sequence: a replaceable third insulating layer 7 at an inner layer made of the dense corundum material; a second insulating layer 6 made of the dense corundum material; and a first insulating layer 4 made of the corundum castable material. The first insulating layer 4 may be provided with a groove with an opening upward, and the coke particles 20 may be contained in the groove. The negative electrode graphite rod 8 and the positive electrode graphite rod 18 may be inserted into the coke particles 20 as the negative electrode and the positive electrode respectively for passing the direct current through the coke particles 20. The third insulating layer 7 may include two arc-shaped dense corundum sheets that can be replaced at any time. The second insulating layer 6 may be a complete dense corundum crucible. The graphite base 13 may be placed on the bottom of the corundum crucible. The metal electric rod 12 can pass through the hole reserved on the corundum crucible and may be threadedly connected to the graphite base 13. The second insulating layer 6 made of the dense corundum material may be wrapped by the first insulating layer 4 formed by pouring the corundum castable, to form the circular furnace of the electrolytic cell without the splicing gaps for containing the electrolyte melt and the aluminum liquid and to serve as the working region for an inert anode 17 and a wettable cathode 16. The net dimensions of the interior of the furnace may be: 300 mm in diameter and 500 mm in depth. An anti-seepage thermal-insulation layer may be provided outside the first insulating layer 4. The anti-seepage thermal-insulation layer may include from the inside to the outside in sequence: the dry barrier material layer 3, the ceramic fiber plate 2, and the steel cell shell.
The wettable cathode 16 may adopt a TiB2—C hot-pressing composite ceramic with a TiB2 content greater than 60% and with a structure of vertical plate. The wettable cathode 16 may be embedded in the mounting slot of the graphite base 13 at the bottom of the electrolytic cell. The cathode 16 and the graphite base 13 may be connected together with the graphite bolts 14, and the surrounding gaps and pits may be filled to be flat with the pounded cathode paste 15. The current of the cathode 16 passes through the graphite base 13 and is led out of the electrolytic cell by the metal electric rod 12 connected to the graphite base 13. The inert anode 17 may be in a shape of vertical plate and arranged in the staggered manner with the cathodes 16, and may be suspended above the electrolytic cell through the guide rod 11. The current of the anode flows through the anode busbar 19 and the guide rod 11 and enters into the electrolytic cell from a top of the electrolytic cell. A thermal insulation sealing layer 10 for a mouth of the furnace of the electrolytic cell may be a protective layer for the guide rod of the anode, and the protective layer may be made of the corundum castable.
The coke particles 20 filled in the groove of the first insulating layer 4 may include 50% petroleum coke particles with a particle size of 1-3 mm, 45% graphite particles with a particle size of 1-3 mm, and 5% mixed graphite powder. The negative electrode graphite rod 8 and the positive electrode graphite rod 18 may be provided as the negative electrode and the positive electrode respectively for the direct current passing through the coke particles 20. When the electrolytic cell reaches the target temperature and remains stable, the DC current of layers of the coke particles 20 is 1.2 kA and the voltage of layers of the coke particles 20 is 4-5 V. When the voltage of layers of the coke particles 20 is greater than 5 V, it is indicated that there is a burning and loss to the coke particles 20, thus it is required to remove the thermal insulation cover 9 and replenish and press the coke particles 20 with a tool, as long as the voltage of layers of the coke particles 20 is restored to be below 5 V. When a heating power needs to be changed, it may be achieved by adjusting a size of the DC current.
In an electrolytic test process, KF—NaF—AlF3 low temperature electrolyte system is used, an electrolytic temperature may be between 800-850° C., a direct current of an electrolytic process may be 100 A, and two wettable cathodes and one inert anode may be used. An electrolytic process requires a continuous supply of an alumina for feeding, and an aluminum water generated at a bottom also needs to be taken out regularly. The third insulating layer 7 may be made of the dense corundum material and replaced approximately every 10 days; the coke particles 20 may be replenished in small amounts every 2 days. When the electrolytic test is progressed for about 1,000 hours, the electrolytic test and heating are stopped due to a need for detecting the inert anode. After the inert anode, the electrolyte, and the aluminum liquid are all taken out to observe the electrolytic cell, the electrolytic cell is still intact.
In some embodiments, referring to
The three-layer insulating side wall of the electrolytic cell may include from the inside to the outside in sequence: a replaceable third insulating layer 7 made of the dense corundum material; a second insulating layer 6 made of a NiFe2O4 based ceramics material; a first insulating layer 4 made of the corundum castable material. The first insulating layer 4 may be provided with a groove with an opening upward, and the coke particles 20 are contained in the groove. The negative electrode graphite rod 8 and the positive electrode graphite rod 18 may be inserted into the coke particles 20 as the negative electrode and the positive electrode respectively for passing the direct current through the coke particles 20. The third insulating layer 7 may include four rectangular dense corundum sheets that can be replaced at any time. The second insulation layer 6 may also include four rectangular NiFe2O4 based ceramic blocks and is connected to edges of the graphite base 13. The second insulating layer 6 may be wrapped by the first insulating layer 4 formed by pouring the corundum castable to form a rectangle furnace of the electrolytic cell without the splicing gaps. The rectangle furnace of the electrolytic cell may be used to contain the electrolyte melt and the aluminum liquid, and serve as the working region for the inert anode 17 and the wettable cathode 16. The net dimensions of the interior of the furnace may be: 320 mm long, 270 mm wide and 500 mm deep. An anti-seepage thermal-insulation layer may be provided outside the first insulating layer 4. The anti-seepage thermal-insulation layer may include from the inside to the outside in sequence: the dry barrier material layer 3, the ceramic fiber plate 2, and the steel cell shell.
The wettable cathode 16 may adopt a TiB2—C hot-pressing composite ceramic with a TiB2 content greater than 60% and with a structure of vertical plate. The wettable cathode 16 may be embedded in the mounting slot of the graphite base 13 at the bottom of the electrolytic cell. The cathode 16 and the graphite base 13 may be connected together with the graphite bolts 14, and the surrounding gaps and pits may be filled to be flat with the pounded cathode paste 15. The current of the cathode 16 passes through the graphite base 13 and is led out of the electrolytic cell by the metal electric rod 12 connected to the graphite base 13. The inert anode 17 may be in a shape of vertical plate and arranged in the staggered manner with the cathodes 16, and may be suspended above the electrolytic cell through the guide rod 11. The current of the anode flows through the anode busbar 19 and the guide rod 11 and enters into the electrolytic cell from a top of the electrolytic cell. A thermal insulation sealing layer 10 for a mouth of the furnace of the electrolytic cell may be a protective layer for the guide rod of the anode, and the protective layer may be made of the corundum castable.
The coke particles 20 filled in the groove of the first insulating layer 4 may include 50% petroleum coke particles with a particle size of 1-3 mm, 45% graphite particles with a particle size of 1-3 mm, and 5% graphite powder. The negative electrode graphite rod 8 and the positive electrode graphite rod 18 may be provided as the negative electrode and the positive electrode respectively for passing the direct current through the coke particles 20. When the electrolytic cell reaches the target temperature and remains stable, the DC current of layers of the coke particles 20 is 1.5 kA and the voltage of layers of the coke particles 20 is 4-5 V. When the voltage of layers of the coke particles 20 is greater than 5 V, it is indicated that there is a burning and loss to the coke particles 20, thus it is required to remove the thermal insulation cover 9 and replenish and press the coke particles 20 with a tool, as long as the voltage of layers of the coke particles 20 is restored to be below 5 V. When a heating power needs to be changed, it may be achieved by adjusting a size of the DC current.
In an electrolytic test process, KF—NaF—AlF3 low temperature electrolyte system is used, an electrolytic temperature may be between 800-850° C., a direct current of an electrolytic process may be 200 A, and two wettable cathodes and one inert anode may be used. The electrolytic process requires a continuous supply of the alumina for feeding, and the aluminum water generated at a bottom also needs to be taken out regularly to always keep the level of the aluminum lower than corrosion-resistant insulating side walls at middle, thereby avoiding the aluminum water from corroding the NiFe2O4 based ceramics material. The third insulating layer 7 may be made of the dense corundum material and may be replaced approximately every 10 days. The coke particles 20 may be replenished in small amounts every 2 days. When the electrolytic test is progressed for about 1,000 hours, the electrolytic test and heating are stopped due to a need for detecting the inert anode. After the inert anode, the electrolyte, and the aluminum liquid are all taken out to observe the electrolytic cell, the electrolytic cell is still intact.
In some embodiments, referring to
The three-layer insulating side wall of the electrolytic cell may include from the inside to the outside in sequence: a replaceable third insulating layer 7 made of the dense corundum material; a second insulating layer 6 made of a material formed by the silicon carbide combining with the silicon nitride; a first insulating layer 4 made of the corundum castable material. The first insulating layer 4 may be provided with a groove with an opening upward, and two first metal heating plates 21 may be provided in the groove. The first stainless steel rod 22 and the second stainless steel rod 23 may be welded on the first metal heating plate 21 to serve as the negative electrode and the positive electrode respectively for passing the direct current through the first metal heating plate 21. The third insulating layer 7 may include four rectangular dense corundum sheets that can be replaced at any time. The second insulating layer 6 may also be composed of four rectangular blocks made of the ceramic formed by the silicon carbide combining with the silicon nitride, and is connected to the edges of the graphite base 13. The second insulating layer 6 may be wrapped by the first insulating layer 4 molded formed by pouring the corundum castable to form the rectangle furnace of the electrolytic cell without the splicing gaps. The rectangle furnace of the electrolytic cell may be used to contain the electrolyte melt, and the aluminum liquid, and serve as the working region for the inert anode 16 and the wettable cathode 17. The net dimensions of the interior of the furnace may be: 320 mm long, 270 mm wide and 500 mm deep. An anti-seepage thermal-insulation layer may be provided outside the first insulating layer 4. The anti-seepage thermal-insulation layer may include from the inside to the outside in sequence: the dry barrier material layer 3, the ceramic fiber plate 2, and the steel cell shell.
The wettable cathode 16 may adopt a TiB2—C hot-pressing composite ceramic with a TiB2 content greater than 60% and with a structure of vertical plate. The wettable cathode 16 may be embedded in the mounting slot of the graphite base 13 at the bottom of the electrolytic cell. The cathode 16 and the graphite base 13 may be connected together with the graphite bolts 14, and the surrounding gaps and pits may be filled to be flat with the pounded cathode paste 15. The current of the cathode 16 passes through the graphite base 13 and is led out of the electrolytic cell by the metal electric rod 12 connected to the graphite base 13. The inert anode 17 may be in a shape of vertical plate and arranged in the staggered manner with the cathodes 16, and may be suspended above the electrolytic cell through the guide rod 11. The current of the anode flows through the anode busbar 19 and the guide rod 11 and enters into the electrolytic cell from a top of the electrolytic cell. A thermal insulation sealing layer 10 for a mouth of the furnace of the electrolytic cell may be a protective layer for the guide rod of the anode, and the protective layer may be made of the corundum castable.
Two first metal heating plates 21 cut from a single piece of 310s stainless steel plate may be disposed in the groove of the first insulating layer 4. The two first metal heating plates 21 may have the same shape and be connected in parallel. The dimensional parameters of each first metal heating plate 21 may be: a thickness of about 10 mm, a width of a cut-out strip of about 40 mm, and a total length of the cut-out strip of about 4000 mm. Two first metal heating plates 21 heat two side walls of the furnace. A parallel resistance of the two first metal heating plates 21 at 800° C. is 0.0068 ohms, with a DC current of 1kA and a voltage of 6.8V. Gaps between the first metal heating plates 21 and the groove may be filled via an industrial oxide filler.
In an electrolytic test process, KF—NaF—AlF3 low temperature electrolyte system is used, an electrolytic temperature may be between 800-850° C., a direct current of an electrolytic process may be 200 A, and two wettable cathodes and one inert anode may be used. The electrolytic process requires a continuous supply of the alumina for feeding, and the aluminum water generated at a bottom also needs to be taken out regularly to always keep the level of the aluminum water lower than corrosion-resistant insulating side walls at middle, thereby avoiding the aluminum water from corroding the material formed by the silicon carbide combining with the silicon nitride. The third insulating layer 7 may be made of the dense corundum material and may be replaced approximately every 10 days. When the electrolytic test is progressed for about 1,000 hours, the electrolytic test and heating are stopped due to a need for detecting the inert anode. After the inert anode, the electrolyte, and the aluminum liquid are all taken out to observe the electrolytic cell, the electrolytic cell is still intact, and a surface of the first metal heating plate 21 is only slightly oxidized.
In some embodiments, referring to
The three-layer insulating side wall of the electrolytic cell may include from the inside to the outside in sequence: a replaceable third insulating layer 7 made of the dense corundum material; a second insulating layer 6 made of the material formed by the silicon carbide combining with the silicon nitride; a first insulating layer 4 made of the corundum castable material. The first insulating layer 4 may be provided with a groove with an opening upward, and two second metal heating plates 24 may be provided in the groove. The third stainless steel rod 25 and the fourth stainless steel rod 26 may be welded on the second metal heating plate 24 to serve as the negative electrode and the positive electrode respectively for passing the direct current through the second metal heating plate 24. The third insulating layer 7 may include four rectangular dense corundum sheets that can be replaced at any time. The second insulating layer 6 may also be composed of eight rectangular blocks made of the ceramic formed by the silicon carbide combining with the silicon nitride, and is connected to the edges of the graphite base 13. The second insulating layer 6 may be wrapped by the first insulating layer 4 molded formed by pouring the corundum castable to form the rectangle furnace of the electrolytic cell without the splicing gaps. The rectangle furnace of the electrolytic cell may be used to contain the electrolyte melt and the aluminum liquid, and serve as the working region for the inert anode 17 and the wettable cathode 16. The net dimensions of the interior of the furnace may be: 960 mm long, 270 mm wide and 500 mm deep. An anti-seepage thermal-insulation layer may be provided outside the first insulating layer side wall 4. The anti-seepage thermal-insulation layer may include from the inside to the outside in sequence: the dry barrier material layer 3, the ceramic fiber plate 2, and the steel cell shell.
The wettable cathode 16 may adopt a TiB2—C hot-pressing composite ceramic with a TiB2 content greater than 60% and be in a structure of vertical plate. The wettable cathode 16 may be embedded in the mounting slot of the graphite base 13 at the bottom of the electrolytic cell. The cathode 16 and the graphite base 13 may be connected together with the graphite bolts 14, and the surrounding gaps and pits may be filled to be flat with the pounded cathode paste 15. The current of the cathode 16 passes through the graphite base 13 and is led out of the electrolytic cell through the graphite base 13 by the metal electric rod 12 connected to the graphite base 13. The inert anode 17 may be in a shape of vertical plate and arranged in the staggered manner with the cathodes 16, and may be suspended above the electrolytic cell through the guide rod 11. The current of the anode flows through the anode busbar 19 and the guide rod 11 and enters into the electrolytic cell from a top of the electrolytic cell. A thermal insulation sealing layer 10 for a mouth of the furnace of the electrolytic cell may be a protective layer for the guide rod of the anode, and the protective layer may be made of the corundum castable.
Two second metal heating plates 24 cut from a single piece of 310s stainless steel plate may be disposed in the groove of the first insulating layer 4. The two second metal heating plates 24 may have the same shape and be connected in parallel. The dimensional parameters of each second metal heating plate 24 may be: a thickness of about 12 mm, a width of a cut-out strip of about 80 mm, and a total length of the cut-out strip of about 8000 mm. Two second metal heating plates 24 heat two side walls of the furnace. The parallel resistance of the two second metal heating plates 24 at 800° C. is 0.0057 ohms, with a DC current of 1.6 kA, and a voltage of 9.12 V. Gaps between the second metal heating plates 24 and the groove may be filled via the industrial oxide filler.
In an electrolytic test process, KF—NaF—AlF3 low temperature electrolyte system is used, an electrolytic temperature may be between 800-850° C., a direct current of an electrolytic process may be 1000 A, and six wettable cathodes 16 and five inert anodes 17 may be used. The electrolytic process requires a continuous supply of the alumina for feeding, and the aluminum water generated at a bottom also needs to be taken out regularly to always keep the level of the aluminum water lower than corrosion-resistant insulating side walls at middle, thereby avoiding the aluminum water from corroding the material formed by the silicon carbide combining with the silicon nitride. The third insulating layer 7 may be made of the dense corundum material and may be replaced approximately every 10 days. When the electrolytic test is progressed for about 2000 hours, the electrolytic test and heating are stopped due to a need for detecting the inert anode. After the inert anode, the electrolyte, and the aluminum liquid are all taken out to observe the electrolytic cell, the electrolytic cell is still intact, and a surface of the second metal heating plate 24 is only slightly oxidized.
The inert anode aluminum electrolytic cell with the vertical structure provided by the embodiments of the present disclosure can achieve the following beneficial technical effects, for example:
(1) The heating device by means of the direct current is arranged in the groove on the first insulating layer, the coke particles or the first metal heating plate or the second metal heating plate is used as the heat generation element. Therefore, a structure is simple, a performance is stable, a service life is long, and a heating by means of the direct current is of a low voltage and a safe operation.
(2) The first insulating layer may be the corundum castable, so that the electrolytic cell ca be not limited in size and scale, so as to meet the electrolytic tests of different scales.
(3) The interior of the electrolytic cell shell may be a structure of three insulating layers. The third insulating layer is a replaceable buffer layer, the second insulating layer is a corrosion-resistant layer, and the first insulating layer is a heating thermal-insulation layer. The following problems are solved: the electrolytic cell needs to be heated and thermal insulated when the scale of the electrolytic cell is small; the side walls within the electrolytic cell shell are easily corroded without a protection of a frozen ledge; and the electrolyte melt easily penetrates through the splicing gaps of the furnace to damage the thermal-insulation layer.
(4) Graphite bolts are used to cooperate with the pounded cathode paste to an achieve effective conductive connection between the cathode and the graphite base. The problem of failure easily occurred when only the pounded cathode paste is relied on or the cathode is directly connected to the metal guide rod was solved.
The above are only optional embodiments of the present disclosure, and are not intended to limit the protection scope sought for by the present disclosure. The equivalent structural transformations made by using the contents of the description and accompanying drawings of the present disclosure, or direct/indirect applications in other related technical fields under the inventive concept of the present disclosure are included within the protection scope sought for by the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202310009797.0 | Jan 2023 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2023/083255 | 3/23/2023 | WO |
