WO2013185538A1

WO2013185538A1 - Electrolysis tank used for aluminum electrolysis and electrolysis process using the electrolyzer

Info

Publication number: WO2013185538A1
Application number: PCT/CN2013/076440
Authority: WO
Inventors: 孙松涛; 方玉林
Original assignee: 内蒙古联合工业有限公司
Priority date: 2012-06-11
Filing date: 2013-05-30
Publication date: 2013-12-19
Also published as: ZA201409512B; CA2877591A1; IN2015DN00216A; CN103484891A; AU2013275995A1; AU2013275995B2; EP2860290B1; EP2860290A1; KR20150022993A; HRP20190669T1; AP2015008184A0; EP2860290A4; CN103484891B; KR101684813B1; PL2860290T3; EA201492226A1; CA2877591C; US20150122664A1; EA030419B1; HUE042500T2

Abstract

An electrolysis tank used for aluminum electrolysis, comprising a tank body, an anode and a cathode arranged within the tank body, also an electrolyte accommodated within the tank body, where at least a part of the anode is submerged in the electrolyte. The anode is arranged above the tank body. The cathode is arranged at the tank bottom and is covered by a certain amount of liquid aluminum. The electrolyte is provided between the anode and the cathode. The electrolyte covers the liquid aluminum. The tank body has arranged on an inner sidewall thereof an insulation layer for use in separating oxygen or the electrolyte from a carbon block. The tank is characterized in that: the constituents of the anode comprise Fe, Cu, Ni, and Sn, where Fe and Cu are the main constituents; the electrolyte consists of 30 to 38 wt% of NaF, 49 to 60 wt% of AlF₃, 1 to 5 wt% of LiF, 1 to 6 wt% of KF, and 3 to 6 wt% of Al₂O₃, where the molar ratio of NaF to AlF₃ is between 1.0 and 1.52. The electrolysis tank is applicable in industrialized production of electrolyzed aluminum.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an electrolytic cell for electrolytic aluminum and an electrolytic process using the same, belonging to the non-ferrous metal smelting industry. BACKGROUND OF THE INVENTION The electrolytic aluminum industry generally uses a conventional Hall-called Heroult dissolved salt electrolytic aluminum process to electrolyze a melting salt of cryolite-alumina in a pre-baked carbon anode electrolytic cell, that is, a cryolite Na ₃ AlF ₆ fluoride salt. The melt is a flux, the A1 ₂ 0 _{3 is} dissolved in the fluoride salt, and the carbon body is used as the anode to be vertically inserted into the electrolytic cell, and the carbon body covered with the aluminum liquid at the bottom of the electrolytic cell is used as the cathode.

After entering a strong direct current, the electrochemical reaction is carried out at the two poles of the electrolytic cell at a high temperature of 940-960 ° C, and the produced aluminum liquid product covers the cathode at the bottom of the electrolytic cell. Due to the high electrolysis temperature, the conventional electrolytic aluminum process has disadvantages such as large electrolyte evaporation, poor working environment, large loss of carbon anodization, and high energy consumption.

In order to reduce the electrolysis temperature, in the prior art, Chinese Patent Publication No. CN101671835A discloses a low-temperature molten salt system for aluminum electrolysis, the molten salt composition of which is A1F ₃ and A1 ₂ 0 ₃ , and KF, NaF, MgF ₂ , CaF. _2. One or more salts of NaCl, LiF, BaF ₂ , which can be operated in a wide range of areas where the electrolysis temperature can be lowered to 680-900 °C.

NaCl is added to the above electrolyte in order to lower the initial crystal temperature of the electrolyte, but NaCl will corrode metal objects such as electrolytic cell fittings at the above electrolysis temperature, and NaCl is highly volatile HC1 toxic gas during electrolysis, so it is difficult to apply; In addition to NaCl, it is also known in the art that lowering the molar ratio of NaF to A1F ₃ can also lower the primary crystal temperature of the electrolyte, but in the current industry, the molar ratio of NaF to A1F ₃ is usually greater than 2.2, because if Further reducing the molar ratio of NaF to A1F ₃ , accompanied by a decrease in the initial crystal temperature of the electrolyte, NaF and A1F ₃ will cause a cathodic "caking" phenomenon during the low-temperature electrolysis. The reason for this cathode "crusting" phenomenon is the electrolysis process. The sodium ions and aluminum ions in the electrolyte accumulate at the cathode to form sodium cryolite. The melting point of the sodium cryolite is high, and it is difficult to melt under low temperature conditions, which causes the surface of the cathode to be covered with a refractory cryolite shell. , which greatly affects the normal electrolysis of the electrolysis process. The problems in the above technology make the industrial application of the electrolyte greatly limited, how to further reduce the initial temperature of the electrolyte, and also avoid the corrosion of the electrolysis device and the harm to the human body, and at the same time ensure the prepared The electrolyte has a suitable electrical conductivity and alumina solubility and does not cause a cathode "crusting" phenomenon, which is an unsolved problem in the prior art. In addition to the need to solve the problem of high electrolysis temperature, in the electrolytic cell of the traditional electrolytic aluminum, the carbon anode is continuously consumed by oxidation during the electrolysis process, so that the carbon anode needs to be continuously replaced; and along with the process of aluminum electrolysis, the anode is continuously generated. Exhaust gas such as carbon dioxide and carbon monoxide. Therefore, in order to reduce the consumption of anode materials in the aluminum electrolysis process while reducing the emission of exhaust gas, many documents for studying anode materials are disclosed in the prior art, for example, Chinese Patent Document CN1443877A discloses an application to aluminum, magnesium and rare earth. An inert anode material of the electrolysis industry, which is composed of a binary or multi-component alloy composed of a metal such as chromium, nickel, iron, cobalt, titanium, copper, aluminum, manganese, etc., and is prepared by a method of smelting or powder metallurgy. The prepared anode material has good electrical and thermal conductivity, and the anode generates oxygen during electrolysis, wherein the first example is 37 wt% cobalt, 18 wt% copper, 19 wt% nickel, 23 wt% iron, 3^^% silver. The alloy material is made into an anode for electrolytic aluminum. In the electrolysis process at 850 ° C, the anode current density is 1.0 Å/cm ² , and the cell pressure is stably maintained at 4.1-4.5 V during the electrolysis process. The purity of aluminum is 98.35%. Although the alloy anode material of the above technique has higher conductivity than the carbon material, has a lower amount of corrosion during electrolysis, and can be processed into any shape. However, the overvoltage of the alloy anode composed of the above metal components is still high, the industrial power consumption is large, the product quality is low, and the use of a large amount of expensive metal materials causes the cost of the anode material to be high and cannot meet the industrialization needs. . In addition, an oxide film is formed on the surface of the alloy anode prepared in the prior art, and after the oxide film is destroyed, the anode material exposed on the surface is oxidized and supplemented with a new oxide film. The alloy anode surface oxide film in the above technology has low oxidation resistance, is easy to further undergo oxidation reaction to form a product which is easily corroded by the electrolyte, and the oxide film has low stability and is easily detached from the anode electrode during electrolysis; After some oxide film is corroded or peeled off, the material exposed on the surface of the alloy anode will react to form a new oxide film. The old and new replacement of the oxide film leads to continuous consumption of the anode material, poor corrosion resistance, and corrosion or shedding. The oxide film enters the liquid aluminum along with the electrolysis process of the alumina, thereby reducing the purity of the aluminum of the final product, so that the produced aluminum product cannot meet the requirements of the national standard and cannot be directly used as a finished product. SUMMARY OF THE INVENTION A first technical problem to be solved by the present invention is that in the prior art, while further reducing the initial crystal temperature of the electrolyte, it is also possible to avoid corrosion of the electrolysis device and harm to the human body, and at the same time, ensure the prepared electrolyte. An electrolyte having suitable conductivity and alumina solubility without causing a cathodic "crustation" phenomenon, the present invention provides a low primary crystal temperature, non-corrosive to metals, non-volatile, suitable electrical conductivity and alumina An electrolytic cell of an electrolyte for electrolytic aluminum which does not cause a cathode "crustation" phenomenon. A second technical problem to be solved by the present invention is that the alloy anode composed of a metal component has a high overvoltage in the prior art, the electrolytic aluminum process consumes a large amount of electricity, and the metal component used is expensive, resulting in an alloy anode. In addition, in the prior art, the oxide film on the surface of the alloy anode has low oxidation resistance and is easy to fall off, resulting in continuous consumption of the alloy anode, poor corrosion resistance, and corrosion or falling off of the oxide film into the liquid aluminum. The purity of the final product aluminum; further proposes an electrolytic aluminum electrolytic cell with low overvoltage and low cost, and the oxide film formed on the surface is strong in oxidation resistance, strong in stability and resistant to electrolyte corrosion. The present invention also provides a process for electrolytic aluminum using the above electrolytic cell. In order to solve the above technical problem, the present invention provides an electrolytic cell for electrolytic aluminum, comprising a tank body, the tank body is provided with an anode and a cathode, and the tank body is further provided with an electrolyte; the anode is disposed in the tank body Above, at least part of the anode is immersed in the electrolyte; the cathode is disposed at the bottom of the tank and covered by a quantity of aluminum liquid; the electrolyte is intermediate the anode and the cathode; and the composition of the anode includes Fe, Cu and Sn, wherein the Fe and Cu are the main components; the electrolyte is composed of 30-38% NaF, 49-60% A1F ₃ , 1-5^% LiF, 1-6 A composition of ^^% of KF and 3-6 wt% of A1 ₂ 0 ₃ wherein the molar ratio of NaF to A1F ₃ is from 1.0 to 1.52. The bottom surface of the anode is kept parallel to the tank body, and the inner side wall of the tank body is provided with an insulating layer for isolating oxygen and the electrolyte from the carbon block. The upper end of the tank body is provided with a groove cover, the groove cover is provided with a vent hole and a feed hole; a cathode rod is disposed in the cathode, and one end of the anode passes through the groove cover and is connected with a wire Column for connecting the anode power supply. The mass ratio of Fe, Cu and Sn is (23 to 40): (36 to 60): (0.2 to 5). The composition of the anode also includes Ni. The anode is composed of Fe, Cu, Ni and Sn, wherein the Fe content is 23 to 40% by weight, the Cu content is 36 to 60% by weight, and the Ni content is 14 to 28% by weight, the Sn The content is 0.2 to 5 wt%. The components of the anode also include A1 and Y. The anode is composed of Fe, Cu, Ni, Sn, Al, and Y, wherein the Fe content is 23 to 40% by weight, the Cu content is 36 to 60% by weight, and the Ni content is 14 to 28% by weight. The content of the Al is greater than zero and less than or equal to 4 wt%, the content of the Y is greater than zero and less than or equal to 2 wt%, and the content of the Sn is 0.2 to 5 wt%. The molar ratio of NaF to A1F ₃ is from 1.12 to 1.52. The primary crystal temperature of the electrolyte is 620-670 °C. The electrolytic aluminum process using the electrolytic cell includes the following steps:

(1) adding a specific amount of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 ₃ to a melting furnace to be mixed and melted into a melt; or, adding a specific amount of NaF, A1F ₃ , LiF, KF to the melting furnace After mixing and melting, A1 ₂ 0 ₃ is further added to obtain a melt;

(2) The melt prepared in the step (1) is heated to 720-760 ° C or higher in a melting furnace, poured into an electrolytic bath, and maintained at a temperature of 720-760 ° C for electrolysis. The temperature of the electrolysis is 730-750 °C. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. The electrolytic aluminum process of the electrolytic cell comprises the following steps:

(2) The melt prepared in the step (1) is heated to 720-760 ° C or higher in a melting furnace, poured into an electrolytic bath, and maintained at a temperature of 720-760 ° C for electrolysis. The temperature of the electrolysis is 730-750 °C. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. The electrolysis cell of the present invention and the electrolysis process using the same have the advantages of:

(1) The electrolytic cell for electrolytic aluminum according to the present invention, comprising a tank body, wherein the tank body is provided with an anode and a cathode, and the tank body is further provided with an electrolyte; the anode is disposed above the tank body, at least part of The anode is immersed in the electrolyte; the cathode is disposed at the bottom of the tank and covered by a quantity of aluminum liquid, the electrolyte is intermediate between the anode and the cathode; and the composition of the anode includes Fe, Cu, and Sn, Wherein the Fe and Cu are the main components; the electrolyte is composed of 30-38% NaF, 49-60 wt% W A1F ₃ , 1-5^% LiF, 1-6^% KF and 3- 6^% of A1 ₂ 0 ₃ composition, wherein the molar ratio of NaF to A1F ₃ is 1.0-1.52. The anode containing metal Sn and the above metal component has high conductivity and low overvoltage, and the cell voltage in the electrolysis cell is about 3.1 to 3.4 V, and the power consumption of the electrolytic aluminum process is small, and the electricity consumption per ton of aluminum is small. The amount of ≤11000k h, the process cost is low; since the anode material is an alloy composed of Fe, Cu and Sn, the oxide film formed on the surface of the anode is resistant to oxidation during electrolysis. It has high properties, is not easily corroded by electrolytes, and the formed oxide film is stable and does not easily fall off, so that the anode has high oxidation resistance and corrosion resistance. It is also because of the oxidation resistance and corrosion resistance of the above anode that the anode material does not cause impurities mixed in the liquid aluminum due to corrosion or shedding, thereby ensuring the purity of the aluminum product, and the purity of the produced aluminum can reach 99.8%. The overvoltage of the alloy anode in the prior art is avoided, the oxidation resistance of the alloy surface oxide film is low, and it is easy to fall off, resulting in continuous consumption of the alloy anode, poor corrosion resistance, and corrosion or falling off oxide film entering the liquid aluminum. This reduces the problem of the purity of the final product aluminum. In addition, the alloy anode has Fe and Cu as main components, and the content ratio is high, which reduces the manufacturing cost of the anode material. The electrolyte used uses a pure fluoride salt system, by limiting the composition of the substances in the electrolyte, and further limiting the content of these substances, and the molar ratio of the NaF to A1F ₃ is 1.0-1.52, so that the primary crystal temperature of the electrolyte is lowered to 640-670 °C, so that the electrolysis process can be electrolyzed at 720-760 °C, reducing the volatilization loss of the fluoride salt, avoiding the corrosion of the electrolyzer and the harm to the human body, improving the working environment, greatly The energy consumption of the electrolysis process is reduced, and the purpose of energy saving and emission reduction is achieved. At the same time, the invention can combine with sodium ions and aluminum ions in the electrolyte to form lithium cryolite and potassium cryolite with low melting point by adding appropriate content of LiF and KF. Therefore, the phenomenon of encrustation does not occur during the electrolysis process; the electrolyte for electrolytic aluminum of the present invention has no CaF ₂ and MgF ₂ addition to the current industry, but a system in which the molar ratio of NaF to A1F ₃ is 1.0-1.52. In addition, a suitable ratio of KF having the function of increasing the solubility and dissolution rate of alumina is added, thereby improving the low molar ratio of electrolyte aluminum to low solubility. Disadvantages; Generally, the conductivity of the electrolyte decreases with decreasing temperature, so the conductivity at a low electrolysis temperature is generally difficult to meet the needs of a normal electrolysis process, and the present invention lowers the electrolysis temperature by lowering the primary crystal temperature of the electrolyte. However, the present invention optimizes the ratio of the components in the electrolyte by adding LiF having a large electrical conductivity, so that the conductivity of the electrolyte at a low temperature can also meet the needs of the electrolysis process, and the current efficiency of the electrolysis process is improved. . The present invention limits the content of LiF to 1-5%, because the content of LiF is too low to improve the conductivity and prevent encrustation, and the content of LiF is too high, which leads to the solubility of alumina. The invention reduces the above two cases by limiting the content of LiF to 1-5%. The electrolysis of the above-mentioned ratio electrolyte in the present invention does not corrode the metal device, thereby improving the use of the electrolysis device. life.

(2) The electrolytic cell for electrolytic aluminum according to the present invention, wherein the anode is composed of Fe, Cu, Ni, Sn, Al, and Y, wherein the content of Fe is 23 to 40% by weight, and the content of Cu is 36. 〜60wt%, the content of Ni is 14 to 28% by weight, the content of A1 is less than or equal to 4% by weight, the content of Y is less than or equal to 2% by weight, and the content of Sn is 0.2 to 5% by weight. The above inert alloy anode also has the advantages of low material cost and high electrical conductivity. In addition, the metal A1 contained in the inert alloy anode has an anti-oxidation effect and can be used as a reducing agent to cause metal thermal reduction with a metal oxide in an inert anode alloy. The reaction prevents the metal of the main component of the inert alloy anode from being oxidized, resulting in a decrease in the electrical conductivity of the alloy anode. Meanwhile, the added metal Y can control the crystal structure of the anode material during the preparation of the inert anode to achieve the purpose of oxidation resistance. .

(3) The electrolytic cell for electrolytic aluminum according to the present invention, wherein a specific content of NaF, A1F ₃ , LiF, KF, and A1 ₂ _{3 3} is mixed, and the obtained mixture is heated to form a melt; or a specific content of NaF is added. A1F ₃ , LiF, KF were mixed, and the obtained mixture was heated until molten, and then A1 ₂ 0 ₃ was added to obtain a melt; then the prepared melt was electrolyzed at 720-760 °C. The electrolysis temperature has a direct influence on the volatilization of the electrolyte, the cathode crust phenomenon, the energy consumption of the process, the electrical conductivity, and the solubility of the alumina, and the inventors of the present invention have conducted long-term research based on the composition of the electrolyte according to the present invention. The content characteristics are matched to set the electrolysis temperature to 720-760 ° C. While increasing the conductivity and the solubility of alumina, the cathode crust phenomenon is prevented, and the evaporation of the electrolyte and the energy consumption of the electrolysis process are greatly reduced. Improve the economic performance of the process. Preferably, the present invention further provides that the electrolysis temperature is 730-750 °C. BRIEF DESCRIPTION OF THE DRAWINGS In order to make the content of the present invention easier to understand, the technical solutions described in the present invention are further described below in conjunction with the accompanying drawings and specific embodiments. 1 is a schematic structural view of an electrolytic cell for electrolytic aluminum according to the present invention; wherein the reference numerals are: 1-slot, 2-anode, 3-cathode, 4-electrolyte, 5-insulating layer, 6-slot cover, 7-exhaust hole, 8-feed hole, 9-terminal, 10-cathode bar, 11-aluminum solution. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrolytic cell for electrolytic aluminum according to the present invention, as shown in FIG. 1, includes a tank body 1 in which an anode 2 and a cathode 3 are disposed, and the anode 2 and cathode 3 can be selected according to actual needs. In any embodiment, in the embodiment, the anode 2 is disposed above the tank body 1, the bottom surface of the anode 2 is kept parallel to the tank body 1, and the cathode 3 is disposed at the bottom of the tank and is fixed. The amount of the aluminum liquid 11 is covered; the tank body 1 is further provided with an electrolyte 4, and the immersion of the anode 2 and the cathode 3 in the electrolyte 4 depends on the structure of the selected electrolytic cell, in this embodiment. At least a portion of the anode 2 is immersed in the electrolyte 4, the cathode 3 is placed at the bottom of the tank and covered by a quantity of aluminum liquid 11; the electrolyte 4 is intermediate the anode 2 and the cathode 3 The electrolyte 4 is coated on the aluminum liquid 11; the composition of the anode 2 includes Fe, Cu and Sn, wherein the Fe and Cu are the main components, and the mass ratio of the Fe, Cu, and Sn is (23 to 40): (36 to 60): (0.2 to 5); 30-38 wt% _3⁄4 NaF, 49-60% A1F ₃ , l-5 wt% _3⁄4 LiF, 1-6 wt% KF, and 3-6^^% A1 ₂ 0 ₃ composition, wherein the NaF and A1F ₃ The molar ratio is from 1.0 to 1.52, preferably from 1.12 to 1.52, and the above-mentioned electrolyte 4 has a primary crystal temperature of from 620 to 670 ° C, preferably from 640 to 670 ° C. On the basis of this, as a variable embodiment, in order to separate the inner side wall of the tank body 1 from the electrolyte 4 and oxygen, to prevent electron transfer between the side wall of the tank body 1 and the electrolyte 4, and electrolyte 4 is corroded to the side wall of the trough body 1, and the inner side wall of the trough body 1 is provided with an insulating layer 5 made of any commercially available insulating material resistant to high temperature and resistant to electrolytes 4, such as corundum, Aluminate spinel refractories, etc. In this embodiment, a carbon block is disposed between the inner side wall of the tank body 1 and the insulating layer 5, and the carbon block and the cathode 3 are integrally formed. Of course, the carbon block and the cathode 3 can also be provided separately. On the basis of the above, in order to separate the electrolytic environment of the electrolytic cell from the outside, and at the same time not hinder the exhaust and the feeding, the upper end of the tank body 1 is provided with a groove cover 6, and the groove cover 6 is provided with a vent hole. The size and position of the vent hole and the feed hole 8 can be arbitrarily selected according to actual needs. In the present embodiment, the vent hole 7 is disposed close to the anode 2. Further, in order to facilitate the connection of the anode 2 and the cathode 3 to the power source, the cathode 3 of the groove bottom is provided with a cathode rod 10 for connecting the cathode 3 power source; one end of the anode 2 passes through the slot cover 6 And connected with a terminal 9 for connecting the anode 2 power supply; the cathode rod 10 and the terminal 9 can be made of any material with good electrical conductivity, including steel, iron and alloy materials. On the basis of this, in order to improve the bonding strength between the metal Fe, Cu and Sn, the anode 2 component further includes Ni, preferably, the anode 2 is composed of Fe, Cu, Ni and Sn, wherein The content of Fe is 23 to 40% by weight, the content of Cu is 36 to 60% by weight, the content of Ni is 14 to 28% by weight, and the content of Sn is 0.2 to 5% by weight. The anode 2 may preferably be composed of Fe, Cu, Ni, Sn, Al and Y. The added Al prevents the other main metal components of the anode 2 from being oxidized and improves the oxidation resistance, and the Y component can be adjusted and controlled to be prepared. The structure of the alloy crystal to achieve the purpose of oxidation resistance, wherein the content of Fe is 23 to 40% by weight, the content of Cu is 36 to 60% by weight, and the content of Ni is 14 to 28% by weight, the A1 The content of the content is less than or equal to 4% by weight, the content of Y is less than or equal to 2% by weight, and the content of the Sn is 0.2 to 5% by weight. The electrolysis temperature at the time of electrolytic aluminum using the above electrolytic cell is 720 to 760 ° C, preferably 730 to 750 ° C. The following description will be made in conjunction with specific embodiments. Example 1 Fe, Cu, Ni and Sn metal blocks were mixed according to the ratio of 23% of Fe, 60% of Cu, 14% of Ni and 3% of Sn, and then heated to a molten state at a high temperature and then cast. Anode 1. The anode 1 had a density of 8.3 g/cm ³ , a specific resistance of 68 μΩ·αη, and a melting point of 1360 °C. The composition of the electrolyte in this example is: NaF, 32%; A1F ₃ , 57%; LiF, 3%; KF, 4%; A1 ₂ 0 ₃ , 4%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ Is 1.12. The primary crystal temperature of the electrolyte in this example was measured to be 640 °C. The conductivity of the electrolyte was ^cm-density - 2.03 g/cm ³ and the saturated concentration of alumina was 5%. The process for electrolytic aluminum using the electrolytic cell of the present invention is:

(1) using an anode 1 and a carbon cathode, the above amounts of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 _{3 are} first melted in a melting furnace to form a melt;

(2) The melt prepared in the step (1) is heated to 720 ° C or higher in a melting furnace, poured into an electrolytic bath, the anode and the cathode are turned on, and electrolysis is carried out at 720 ° C for 40 hours. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. During the electrolysis process, there is no crust at the bottom of the tank. The cell voltage of the electrolyzer is 3.1V. The electricity consumption per ton of aluminum in the electrolysis process is 10040kwh, and the purity of the produced aluminum is 99.85%. Example 2 Fe, Cu, Ni, and Sn metal blocks were mixed in a ratio of 40 wt% of Fe, 36% of Cu, 19% of Ni, and 5% of Sn, and then heated at a high temperature to a molten state and then cast. Anode 2. The anode had a density of 8.1 g/cm ³ , a specific resistance of 76.8 μΩ, and a melting point of 1386 ° C. The composition of the electrolyte in this example is: NaF, 38%; A1F ₃ , 50%; LiF, 2%; KF, 5%; A1 ₂ 0 ₃ , 5%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ Is 1.52. The properties of the electrolyte described in this example were measured, and as a result, the primary crystal temperature of the electrolyte in this example was 670 °C. Electrolyte

The density was -2.05 g/cm ³ and the saturated concentration of alumina was 6%. The process for electrolytically using aluminum in the electrolytic cell according to the present invention is as follows: (1) using the anode 2 and the carbon cathode, the above amount of NaF, A1F ₃ , LiF, KF is added to dissolve in the melting furnace first. And adding the above amount of A1 ₂ 0 _{3 to} melt to obtain a melt;

(2) The melt prepared in the step (1) was heated to 760 ° C or higher in a melting furnace, poured into an electrolytic bath, and the power supply of the anode and the cathode was turned on, and electrolysis was carried out at 760 ° C for 40 hours. During the electrolysis process, there is no crust at the bottom of the tank. The cell voltage of the electrolyzer is 3.39V. The electricity consumption per ton of aluminum in the electrolysis process is 10979kwh, and the purity of the produced aluminum is 99.82%. Example 3 Fe, Cu, Ni and Sn metal blocks were mixed according to the ratio of 25% of Fe, 46.8% of Cu, 28% of Ni and 0.2% of Sn, and then heated at a high temperature to a molten state and then cast. Anode 3. The anode had a density of 8.2 g/cm ³ , a specific resistance of 72 μΩ·αη, and a melting point of 1,350 °C. The composition of the electrolyte in this example is: NaF, 32%; A1F ₃ , 57%; LiF, 3%; KF, 4%; A1 ₂ 0 ₃ , 4%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ Is 1.12. The properties of the electrolyte described in this example were measured, and as a result, the initial crystal temperature of the electrolyte in this example was 640 °C. The conductivity of the electrolyte - Ι. ό Ω ^ η - ¹ , density - 2.03 g / cm ³ , alumina saturation concentration 5%. The process for electrolytic aluminum using the electrolytic cell of the present invention is:

(1) using the anode 3 and the carbon body cathode, the above amounts of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 _{3 are} first melted in a melting furnace to form a melt;

(2) The melt prepared in the step (1) is heated to 730 ° C or higher in a melting furnace, poured into an electrolytic cell, and the power supply of the anode and the cathode is turned on, and electrolysis is carried out at 730 ° C for 40 hours. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. During the electrolysis process, there is no crust at the bottom of the tank. The cell voltage of the electrolyzer is 3.15V. The electricity consumption per ton of aluminum in the electrolysis process is 10202k h, and the purity of the produced aluminum is 99.85%. Example 4 The Fe, Cu, Ni, and Sn metal blocks were mixed at a ratio of 24.2% Fe, 60% Cu, 14% Ni, and 0.2 wt% Sn, and then heated to a molten state at a high temperature, and then The 1.8% by mass of the A1 metal block was added to continue the melt mixing, and finally 0.8% of the Y metal block was melt-mixed and cast to obtain the anode 4. The anode had a density of 8.3 g/cm ³ , a specific resistance of 68 μΏ·η, and a melting point of 1360 °C. The composition of the electrolyte in this example is: NaF, 32%; A1F ₃ , 57%; LiF, 3%; KF, 4%; A1 ₂ 0 ₃ , 4%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ Is 1.12. The properties of the electrolyte described in this example were measured, and as a result, the initial crystal temperature of the electrolyte in this example was 640 °C. The conductivity of the electrolyte was ^cm-density - 2.04 g/cm ³ and the saturated concentration of alumina was 6%. The process for electrolytic aluminum using the electrolytic cell of the present invention is:

(1) using the anode 4 and the carbon body cathode, the above amounts of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 _{3 are} first melted in a melting furnace to form a melt;

(2) The melt prepared in the step (1) is heated to 750 ° C or higher in a melting furnace, poured into an electrolytic cell, and the power supply of the anode and the cathode is turned on, and electrolysis is carried out at 750 ° C for 40 hours. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. During the electrolysis process, there is no crust at the bottom of the tank. The cell voltage of the electrolyzer is 3.12V. The electricity consumption per ton of aluminum in the electrolysis process is 10105kwh, and the purity of the produced aluminum is 99.8%. Example 5 The Fe, Cu, Ni and Sn metal blocks were mixed at a ratio of 40% by mass of Fe, 36% by weight of Cu, 14.9% by weight of Ni and 5% by weight of Sn, and then heated to a molten state at a high temperature, and then 0.1% by mass of the A1 metal block was added to continue the melt mixing, and finally 0.1 wt% of the Y metal block was melt-mixed and cast to obtain the anode 5. The anode had a density of 8.1 g/cm ³ , a specific resistance of 76.8 μΩ, and a melting point of 1386 ° C. The composition of the electrolyte in this example is: NaF, 30%; A1F ₃ , 60%; LiF, 1%; KF, 6%; A1 ₂ 0 ₃ , 3%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ Is 1.0. The properties of the electrolyte described in this example were measured, and as a result, the primary crystal temperature of the electrolyte in this example was 620 °C. The conductivity of the electrolyte - Ι ό Ω ^ η - ¹ , density - 2.03 g / cm ³ , alumina saturation concentration 5%. The process for electrolytic aluminum using the electrolytic cell of the present invention is:

(1) using the anode 5 and the carbon cathode, the above amounts of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 _{3 are} first melted in a melting furnace to form a melt;

(2) The melt prepared in the step (1) is heated to 720 ° C or higher in a melting furnace, poured into an electrolytic bath, the anode and the cathode are turned on, and electrolysis is carried out at 720 ° C for 40 hours. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. There is no crust at the bottom of the electrolysis process tank. The cell voltage of the electrolysis cell is 3.27V. The electricity consumption per ton of aluminum in the electrolysis process is 10591kwh, and the purity of the produced aluminum is 99.81%. Example 6 The Fe, Cu, Ni, and Sn metal blocks were mixed at a ratio of 25 wt% of Fe, 38% of Cu, 28% of Ni, and 4% of Sn, and then heated to a molten state at a high temperature, and then 4% by weight of the A1 metal block was added to continue the melt mixing, and finally, 1% of the Y metal block was melt-mixed and cast, and the anode 6 was obtained. The anode had a density of 8.2 g/cm ³ , a specific resistance of 70 Mi > cm, and a melting point of 1365 ° C. The composition of the electrolyte in this example is: NaF, 38%; A1F ₃ , 54%; LiF, 4%; KF, 1%; A1 ₂ 0 ₃ , 3%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ Is 1.4. The properties of the electrolyte described in this example were measured, and as a result, the primary crystal temperature of the electrolyte in this example was 670 °C. Electrolyte conductivity - Ι

, density -2.05g / cm ³ , alumina saturation concentration of 6%. The process for electrolytic aluminum using the electrolytic cell of the present invention is:

(1) using the anode 6 and the carbon body cathode, the above amounts of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 _{3 are} first melted in a melting furnace to form a melt;

(2) The melt prepared in the step (1) is heated to 760 ° C or higher in a melting furnace, poured into an electrolytic cell, and the power supply of the anode and the cathode is turned on, and electrolysis is carried out at 760 ° C for 40 hours. In the electrolysis process, the A1 ₂ 0 ₃ is quantitatively replenished. During the electrolysis process, there is no crust at the bottom of the tank, the cell voltage of the electrolyzer is 3.35V, the electricity consumption per ton of aluminum during electrolysis is 10850kwh, and the purity of the produced aluminum is 99.83. %. Example 7 The Fe, Cu, Ni, and Sn metal blocks were mixed in a ratio of 40% by mass of Fe, 36.5% by weight of Cu, 18% by weight of Ni, and 3% by weight of Sn, and then heated to a molten state at a high temperature, and then 1.5% by mass of the A1 metal block was added to continue the melt mixing, and finally, 1 wt% of the Y metal block was melt-mixed and cast, and then the anode 7 was obtained. The anode had a density of 8.1 g/cm ³ , a specific resistance of 76.8 μΩ, and a melting point of 1386 ° C. The composition of the electrolyte in this example is: NaF, 34%; A1F ₃ , 49%; LiF, 5%; KF, 6%; A1 ₂ 0 ₃ , 6%, wherein the molar ratio of NaF to aluminum fluoride A1F ₃ It is 1.39. The properties of the electrolyte described in this example were measured, and as a result, the primary crystal temperature of the electrolyte in this example was 660 °C. The conductivity of the electrolyte was ^cm-density - 2.05 g/cm ³ and the saturated concentration of alumina was 6%. The process for electrolytic aluminum using the electrolytic cell of the present invention is:

(1) using the anode 7 and the carbon body cathode, the above amounts of NaF, A1F ₃ , LiF, KF, A1 ₂ 0 _{3 are} first melted in a melting furnace to form a melt;

(2) The melt prepared in the step (1) is heated to 760 ° C or higher in a melting furnace, poured into an electrolytic cell, and the power supply of the anode and the cathode is turned on, and electrolysis is carried out at 760 ° C for 40 hours. Quantitatively replenish A1 ₂ 0 ₃ during electrolysis. During the electrolysis process, there is no crust at the bottom of the tank. The cell voltage of the electrolyzer is 3.38V. The electricity consumption per ton of aluminum in the electrolysis process is 10947k h, and the purity of the produced aluminum is 99.8%. The electrolytic cell in the above embodiment is any one of the electrolytic cells described in the present invention. The specific embodiments of the present invention have been described in detail in the above embodiments, and those skilled in the art should understand that any form of modification and details of the changes made on the basis of the present invention are claimed in the present invention. .

Claims

Claim

An electrolytic cell for electrolytic aluminum, comprising a tank body (1), wherein the tank body (1) is provided with an anode (2) and a cathode (3), and the tank body (1) is further provided with an electrolyte ( 4); the anode (2) is disposed above the tank body (1), at least a portion of the anode (2) is immersed in the electrolyte (4); the cathode (3) is disposed at the bottom of the tank Covered by a quantity of aluminum liquid (11); the electrolyte (4) is intermediate between the anode (2) and the cathode (3); characterized in that the composition of the anode (2) comprises Fe, Cu and Sn, wherein the Fe and Cu are the main components; the electrolyte (4) is composed of NaF of 30-38\¥, A1F _{3 of} 49-60\¥, l-5wt W LiF, 1-6\¥ KF and 3-6\¥1% of A1 ₂ 0 ₃ composition, wherein the molar ratio of NaF to A1F ₃ is 1.0-1.52.

The electrolytic cell according to claim 1, characterized in that the bottom surface of the anode (2) is kept parallel to the tank body (1), and the inner side wall of the tank body (1) is provided with an insulating layer ( 5) for isolating oxygen and the electrolyte (4) from the carbon block.

The electrolytic cell according to claim 1 or 2, wherein the upper end of the tank body (1) is provided with a tank cover (6), and the tank cover (6) is provided with a vent hole (7) And a feed hole (8); a cathode rod (10) is disposed in the cathode (3), and one end of the anode (2) passes through the groove cover (6) and is connected with a terminal (9). Used to connect to a power source.

The electrolytic cell according to any one of claims 1 to 3, wherein the mass ratio of Fe, Cu and Sn is (23 to 40): (36 to 60): (0.2 to 5).

The electrolytic cell according to any one of claims 1 to 4, characterized in that the composition of the anode (2) further comprises Ni.

The electrolytic cell according to claim 5, wherein the anode (2) is composed of Fe, Cu, Ni, and Sn, wherein the Fe content is 23 to 40% by weight, and the Cu content is 36 to 60% by weight, the content of Ni is 14 to 28 wt%, and the content of Sn is 0.2 to 5 wt%.

The electrolytic cell according to any one of claims 1 to 6, wherein the composition of the anode (2) further comprises 八1 and ¥.

The electrolytic cell according to claim 7, wherein the anode (2) is composed of Fe, Cu, Ni, Sn, Al, and Y, wherein the Fe content is 23 to 40% by weight, The content of Cu is 36 to 60% by weight, the content of Ni is 14 to 28% by weight, the content of A1 is greater than zero and less than or equal to 4% by weight, and the content of Y is greater than zero and Less than or equal to 2% by weight, the content of the Sn is 0.2 to 5 wt%.

The electrolytic cell according to any one of claims 1 to 8, wherein the molar ratio of NaF to A1F ₃ is from 1.12 to 1.52.

The electrolytic cell according to any one of claims 1 to 9, characterized in that the primary crystal temperature of the electrolyte (4) is 620-670 °C o

11. An electrolytic aluminum process using the electrolytic cell of any of claims 1-10, comprising the steps of:

(2) The melt prepared in the step (1) is heated to 720-76 CTC or more in a melting furnace, poured into an electrolytic bath, and subjected to electrolysis at a temperature of 720-760 °C.

12. The electrolytic aluminum process according to claim 11, wherein the electrolysis has a temperature of 730 to 750 °C.

13. The electrolytic aluminum process according to claim 11 or 12, characterized in that A1 ₂ 0 ₃ is quantitatively replenished during electrolysis.