Conductive paste, green body, carbon block and application thereof

Abstract

The application provides a conductive paste, which comprises dry materials and a first resin, wherein the dry materials comprise aggregates and powders, and the preparation steps of the conductive paste are as follows: mixing the powders and the first resin at a first mixing temperature to obtain a powder paste, wherein the first mixing temperature is controlled in a temperature range in which the weight loss of the first resin during mixing is less than or equal to 20% of the total mass of the first resin; and mixing the powder paste and the aggregates at a second mixing temperature to obtain the conductive paste, wherein the second mixing temperature is controlled in a temperature range in which the solidification amount of the first resin during mixing is less than or equal to 30% of the remaining mass of the first resin. In the application, the resin is first mixed with the powders, so that the resin can be uniformly dispersed in the powders to prepare a powder paste with uniform texture; and the powder paste can effectively bond the aggregates and be pressed into the open pores of the aggregates. The application also provides a green body with high compressive strength and a carbon block with good conductivity.

Description

Technical Field

[0001] This application relates to the field of carbon materials technology, specifically to a conductive paste, green embryo, carbon block, and their applications. Background Technology

[0002] The paste, green pellets, and carbon blocks used in current aluminum electrolysis cathodes and anodes (electrodes) are made from dry materials and coal tar pitch. The dry materials include aggregates and powders. Aggregates are obtained by crushing large pieces of material, and powders are obtained by grinding small pieces of material. The dry materials are preheated and mixed at high temperatures (generally not lower than 180℃) to obtain a uniformly sized dry-mixed material. This dry-mixed material is then kneaded with high-temperature liquid pitch at around 180℃ to obtain a paste. The paste is then shaped into paste blocks or green pellets. The production of paste, green pellets, and carbon blocks consumes a large amount of coal tar pitch and generates a large amount of pitch fumes. Incomplete treatment of these fumes pollutes the environment and seriously affects the application of coal tar pitch. Therefore, reducing the amount of coal tar pitch used and replacing it with other binders is of great significance for the production of paste, green pellets, and carbon blocks.

[0003] Currently, when resin binders are used instead of coal tar binders, the conditions required for the resin to remain stable are stringent, and the initial weight loss and curing temperatures are relatively low. Therefore, it is generally believed that higher kneading temperatures will cause the resin to lose weight and cure prematurely, failing to effectively bind the dry materials together. This easily leads to problems such as poor adhesion, poor flowability, poor plasticity, and difficulty in molding the kneaded paste. It is also believed that the process of preparing a paste by kneading at room temperature and then molding it at a higher temperature is prone to bubbling, cracking, or pores due to the rapid volatilization and discharge of resin during molding. This results in low bulk density and high resistivity of the carbon blocks, which cannot meet the requirements of aluminum electrolysis. Therefore, when resin is used as a binder in this field, cold mixing, cold kneading, and cold molding are employed. That is, the dry materials are mixed at room temperature to obtain a dry mixture, which is then kneaded with room-temperature resin to obtain a paste. The paste is then molded at room temperature to obtain paste blocks or green embryos. However, the strength of the green embryos after demolding is low, and they are easily damaged during transportation, resulting in a low yield. This makes it difficult to efficiently manufacture and widely promote the application of products, hindering industrialization.

[0004] Meanwhile, the mixed dry materials and resin are kneaded together to make a paste. However, the high price and small quantity of resin make it difficult to ensure uniform distribution of resin in the dry mixture. The resulting paste has uneven composition, and some dry materials may not even be coated with resin. This can lead to problems such as excessive carbon residue and deterioration of the electrolytic cell during use. In addition, to reduce the viscosity of the resin and improve its fluidity, a certain amount of organic solvent, such as alcohol, is usually added to the resin to ensure that the resin wets and impregnates the dry mixture. However, during the curing and high-temperature calcination of the paste and the green body, the above-mentioned organic solvent will produce a large amount of volatiles, which can easily cause problems such as anode cracks, blistering, high porosity, low bulk density, and high resistivity. This can affect the normal use of the product in the aluminum electrolytic cell, or even cause the product to be scrapped or affect the life of the electrolytic cell.

[0005] The manufacturing processes for carbon electrodes, carbon saggers, and battery negative electrode materials used in industrial electric furnaces (including submerged arc furnaces) are similar to those for existing aluminum electrolysis cathodes and anodes. If the binder used—coal tar pitch—is replaced with resin, the aforementioned shortcomings will still exist. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology and to efficiently produce pastes, green bodies, and carbon blocks that meet the conductivity requirements, this application aims to provide a conductive paste, green body, and carbon block to solve the problems of uneven resin distribution in dry mixed materials, uneven paste composition and texture, low bulk density, high resistivity, low strength, difficult transfer, and inability to be efficiently and massively produced and promoted when using resin as a binder for pastes, green bodies, or carbon blocks.

[0007] The technical solution of this application is as follows:

[0008] 1. A conductive paste, comprising:

[0009] Dry materials and a first resin, wherein the dry materials include aggregates and powders.

[0010] The preparation steps of the conductive paste are as follows:

[0011] The powder and the first resin are kneaded at a first kneading temperature to obtain a powder paste, wherein the first kneading temperature is controlled within a temperature range in which the weight loss of the first resin during kneading is less than or equal to 20% of the total mass of the first resin.

[0012] The powder paste and the aggregate are kneaded at a second kneading temperature to obtain a conductive paste, wherein the second kneading temperature is controlled within the temperature range where the amount of the first resin cured during kneading is less than or equal to 30% of the mass of the remaining first resin.

[0013] 2. The paste according to item 1,

[0014] The first resin is selected from one or two of thermosetting resins and thermoplastic resins;

[0015] Preferably,

[0016] The first resin is selected from one or more of phenolic resin, epoxy resin, epoxy phenolic resin, furan resin, and polyurethane resin.

[0017] 3. The paste according to item 1,

[0018] The aggregate is aggregate treated with a binder;

[0019] Preferably,

[0020] Before mixing the powder paste and the aggregate, the aggregate is impregnated in the binder or the aggregate and the binder are kneaded together; or...

[0021] Before mixing the powder paste and the aggregate, a portion of the aggregate is impregnated in the binder or a portion of the aggregate and the binder are mixed, and then mixed with the remaining portion of the aggregate.

[0022] 4. The paste according to item 3,

[0023] The adhesive is selected from one or more of asphalt, furfural, secondary resin, and lignin.

[0024] 5. The paste according to any one of items 1 to 4,

[0025] Before mixing the powder paste and the aggregate, the aggregate or the binder-treated aggregate is preheated and mixed to 30-220°C.

[0026] 6. The paste according to item 1,

[0027] The powder is selected from one or more of the following: petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrocalcined anthracite.

[0028] The aggregate is selected from one or more of the following: petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrocalcined anthracite.

[0029] 7. The paste according to item 1,

[0030] Based on particle size, dry materials are divided into aggregates and powders. Larger particles are aggregates, and smaller particles are powders.

[0031] The particle size range for distinguishing aggregates from powders is 2 to 0.06 mm, preferably 0.5 to 0.075 mm, and more preferably 0.075 mm.

[0032] 8. The paste according to item 1, wherein the paste is pressed into paste blocks of regular or irregular shape.

[0033] 9. A method for preparing a conductive paste, comprising the following:

[0034] The powder and the first resin are mixed at a first kneading temperature to obtain a powder paste, wherein...

[0035] The first kneading temperature is controlled within the temperature range where the weight loss of the first resin during kneading is less than or equal to 20% of the total mass of the first resin.

[0036] The powder paste and the aggregate are kneaded at a second kneading temperature to obtain a conductive paste, wherein the second kneading temperature is controlled within the temperature range where the amount of the first resin cured during kneading is less than or equal to 30% of the mass of the remaining first resin.

[0037] 10. The method described in item 9,

[0038] The first resin is selected from one or two of thermosetting resins and thermoplastic resins;

[0039] Preferably,

[0040] The first resin is selected from one or more of phenolic resin, epoxy resin, epoxy phenolic resin, furan resin, and polyurethane resin.

[0041] 11. According to the method described in item 9,

[0042] The aggregate is aggregate treated with a binder;

[0043] Preferably,

[0044] Before mixing the powder paste and the aggregate, the aggregate is impregnated in a binder or the aggregate and the binder are kneaded; or...

[0045] Before mixing the powder paste and the aggregate, a portion of the aggregate is impregnated in the binder or a portion of the aggregate and the binder are mixed, and then mixed with the remaining portion of the aggregate.

[0046] 12. According to the method described in item 11,

[0047] The adhesive is selected from one or more of asphalt, furfural, secondary resin, and lignin.

[0048] 13. The method described according to any one of items 9 to 12,

[0049] Before mixing the powder paste and the aggregate, the aggregate or the binder-treated aggregate is preheated and mixed to 30-220°C.

[0050] 14. According to the method described in item 9,

[0051] The powder is selected from one or more of the following: petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrocalcined anthracite.

[0052] The aggregate is selected from one or more of the following: petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrocalcined anthracite.

[0053] 15. According to the method described in item 9,

[0054] Based on particle size, dry materials are divided into aggregates and powders. Larger particles are aggregates, and smaller particles are powders.

[0055] The particle size range for distinguishing aggregates from powders is 2 to 0.06 mm, preferably 0.5 to 0.075 mm, and more preferably 0.075 mm.

[0056] 16. According to the method described in item 9, the paste is pressed into paste blocks of regular or irregular shape.

[0057] 17. A green embryo for conductive purposes,

[0058] The conductive paste described in any one of items 1 to 8 or the conductive paste prepared by any one of items 9 to 16 is subjected to molding treatment to obtain a conductive green embryo.

[0059] Preferably, the temperature of the mold used for molding is 50-300℃.

[0060] 18. A method for preparing a conductive green embryo, comprising,

[0061] The conductive paste described in any one of items 1 to 8 or the conductive paste prepared by any one of items 9 to 16 is subjected to molding treatment to obtain a conductive green blank.

[0062] Preferably, the temperature of the mold used for molding is 50-300℃.

[0063] 19. A carbon block for conducting electricity,

[0064] The conductive green blank described in item 17 or the conductive green blank prepared by the method described in item 18 is calcined to obtain a conductive carbon block;

[0065] Preferably, the calcination temperature is 650-1300℃ or the electrolysis temperature.

[0066] 20. A method for preparing a conductive carbon block, comprising,

[0067] The conductive green blank described in item 17 or the conductive green blank prepared by the method described in item 18 is subjected to calcination treatment to obtain a conductive carbon block;

[0068] Preferably, the calcination temperature is 650-1300℃ or the electrolysis temperature.

[0069] 21. The application of a conductive carbon block as described in item 19 or a conductive carbon block prepared by the method described in item 20 in electrolytic aluminum, carbon electrodes, crucibles, and negative electrode plates.

[0070] Compared with the prior art, the beneficial effects of this application are as follows:

[0071] (1) Eliminate the technical bias in the field that the process of first mixing resin with powder to make powder paste, and then mixing powder paste with aggregate, not only increases the process flow, but also cannot overcome the problems of easy segregation of powder paste, difficulty in storage and transportation, difficulty in pressing powder paste into aggregate, and the need for the resin composition to remain stable and not solidify during the preparation of paste and product molding to ensure smooth product manufacturing and quality. In practice, it has been proven that reasonable changes in resin composition and partial solidification during product preparation are conducive to the efficient production of high-quality carbon blocks with resin as binder and are conducive to large-scale promotion and use.

[0072] (2) Compared with the prior art, this application adds a step of making powder paste, that is, the resin is first mixed with the powder, which uses the powder as a carrier and dispersant for the resin, and can evenly disperse the resin into the powder. When the powder and resin are mixed, the powder will not be broken, and the mixing time requirement is not strict, until the resin is evenly dispersed in the powder to make a powder paste with uniform texture.

[0073] (3) The prepared powder paste has the characteristics of uniform distribution of resin in powder, no segregation of resin in powder paste, uniform texture of powder paste, strong plasticity, easy dispersion in aggregate, certain adhesive force, and large quantity. It can effectively bond aggregate and be pressed into the open pores of aggregate, and is easy to store and transport.

[0074] (4) The powder paste prepared in this application can be used as a binder for bonding aggregates. Its easy dispersion and dispersibility when mixed with aggregates replaces the stringent requirements of existing mixing technology on resin performance. During mixing, the powder paste has good dispersibility and is easier to disperse and distribute evenly in aggregates than the resin in the prior art. It also protects the aggregates from breakage during the mixing process better than the prior art, keeps the aggregate particle size stable and does not damage the particle size performance. The resulting carbon blocks have high bulk density and good conductivity.

[0075] (5) During the mixing process of powder paste and aggregate, by increasing the mixing temperature or aggregate temperature to increase the temperature of the paste during the mixing process, some gas is discharged, which helps to reduce the amount of gas discharged during the curing and firing of the green body. Thus, without producing cracks or bubbles, the speed and quality of curing, molding and firing are improved, and efficiency and energy saving are increased.

[0076] (6) In the prior art, the weight of a single green embryo generally exceeds 800 kg, and its volume is large, such as a length exceeding 1500 mm and a width exceeding 660 mm. The strength of green embryos prepared by room temperature kneading molding technology is low, and the strength cannot even be measured, which seriously affects the storage, transportation and efficient large-scale production of the products. With the technical solution of this application, the paste temperature is high and the molding temperature is high, which promotes the solidification of part of the paste during the molding process, especially forming a solidified layer around the green embryo. This avoids or weakens the elastic aftereffect problem that is common in the prior art, improves the strength of the product, and makes the strength greater than or equal to 37 MPa, which meets the strength requirements for storage and transportation. The molding speed is fast, which can realize efficient large-scale production and application. At the same time, it further improves the physicochemical properties of the carbon block, such as further increasing the bulk density and further decreasing the resistivity. It eliminates the technical prejudice in the industry that the rapid volatilization and discharge of resin during high-temperature molding makes the product prone to blistering and cracking or pores, resulting in low bulk density and high resistivity, which is difficult to meet the requirements of aluminum electrolysis.

[0077] (7) In addition to being used to prepare the cathode and anode of aluminum electrolysis, the technical solution of this application can also be used to prepare carbon electrodes for industrial electric furnaces (including submerged arc furnaces), carbon saggers, carbon negative electrode plates used in the preparation of battery negative electrode materials, and other related carbon materials. Attached Figure Description

[0078] Figure 1 This is a schematic diagram of the carbon block in Example 3-1;

[0079] Figure 2 This is a schematic diagram of the carbon block in Comparative Example 3-1. Detailed Implementation

[0080] Although the present invention has been disclosed above with reference to embodiments, it is not intended to limit the present invention. Anyone skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the appended patent application.

[0081] The three commonly used room temperature methods in existing technologies are: room temperature mixing, room temperature kneading, and room temperature molding, which are essentially three "cold" processes. These methods aim to prevent resin weight loss and curing, thereby avoiding any impact on the paste's adhesion, flowability, plasticity, and whether it can be molded.

[0082] In this application, mixing and kneading are distinct: mixing refers to the process of uniformly distributing dry materials of different particle sizes using methods such as mechanical stirring, without adding a binder. Kneading, on the other hand, refers to the process of adding a binder to dry materials of different particle sizes, using mechanical stirring to uniformly distribute the materials, and ensuring that the binder (or powder paste) thinly and evenly coats the surface of the powder particles and penetrates into the micropores on the surface of the powder particles, giving the materials a certain degree of plasticity and density. Mixing and kneading can be completed in two stages within a single kneading machine, which is an intermittent mixing and kneading process that saves investment but is inefficient. To improve efficiency, a double-layer preheating kneading machine can be used, where the upper layer preheats or preheats the mixed dry materials, and the lower layer first mixes the powder with resin to form a powder paste, which is then kneaded with the dry materials mixed from the upper layer. This relay-style mixing and kneading can be performed simultaneously.

[0083] In this application, a two-kneading, three-temperature method is used. Besides mixing, the two-kneading process involves first kneading the powder and resin to prepare a powder paste, then kneading the powder paste with aggregate / mixed aggregate / aggregate treated with a binder. In this case, the powder paste acts as a binder. The three-temperature method involves controlling the weight loss during the first kneading, aiming for minimal weight loss, ideally zero, when the final product is a paste. The second kneading temperature controls the curing amount, also aiming for low curing amount, ideally zero, when the final product is a paste, to maintain the plasticity and flowability of the product, or to minimize its impact on the plasticity and flowability. The third temperature is the molding temperature, ensuring sufficient strength of the molded carbon block. However, the strength of the final product (paste) is not required, and high-temperature molding is not necessary.

[0084] This application provides a conductive paste, comprising: a dry material and a first resin, wherein the dry material includes aggregate and powder, and the preparation steps of the conductive paste are as follows: the powder and the first resin are kneaded at a first kneading temperature to obtain a powder paste, wherein the first kneading temperature is controlled within a temperature range in which the weight loss of the first resin during kneading is less than or equal to 20% of the total mass of the first resin.

[0085] The powder paste and the aggregate are kneaded at a second kneading temperature to obtain a conductive paste, wherein the second kneading temperature is controlled within the temperature range where the amount of the first resin cured during kneading is less than or equal to 30% of the mass of the remaining first resin.

[0086] The powder paste and paste described in this application can be implemented in the same workshop or factory, or in different workshops or factories respectively.

[0087] The powder paste prepared in this application encapsulates the powder with resin, ensuring uniform resin distribution without segregation and easy dispersion within the aggregate. The powder paste possesses characteristics of uniform texture, strong plasticity, good adhesion, and high quantity, effectively binding the aggregate and being pressed into its open pores. However, aggregate cannot be mixed with resin before being mixed with powder because the porosity of aggregate is much greater than that of powder. A large amount of resin easily penetrates its pores and does not easily diffuse into the powder. Furthermore, the high resistance during curing and carbonization of the resin within the aggregate pores makes it difficult for gas to escape, easily causing product cracks. By replacing resin with powder paste, which is pressed or squeezed into the open pores of the aggregate and coats the aggregate surface, the amount of resin used is reduced without affecting aggregate adhesion, lowering product costs. The resistance encountered by the gas generated during curing and carbonization is low, resulting in high product bulk density and good electrical conductivity.

[0088] In this application, during the process of kneading the powder and the first resin at the first kneading temperature, the amount of reduction in the mass of the first resin is also referred to as the first resin weight loss. If the first resin loses weight, the first resin weight loss is less than or equal to 20% of the total mass of the first resin.

[0089] In this application, a preferred method for determining the first kneading temperature is to determine the first kneading temperature range by measuring the weight loss of the first resin using equipment including but not limited to a balance, drying oven, muffle furnace, etc.

[0090] In this application, during the process of kneading the powder paste and aggregate at the second kneading temperature, if the first resin solidifies, the amount of solidified first resin is less than or equal to 30% of the remaining first resin mass.

[0091] In this application, the amount of cured material (i.e., the percentage of the mass of the first resin cured to the remaining first resin) is mainly determined by the second kneading temperature, but the amount of cured material will increase as the kneading time (i.e., the kneading time of the powder paste and aggregate) is extended.

[0092] In this application, the preferred method for determining the second kneading temperature is to determine the amount of the first resin cured by methods and equipment including but not limited to differential scanning calorimetry (DSC) and thermogravimetric analysis, thereby determining the range of the second kneading temperature.

[0093] The temperature ranges for the first and second kneading temperatures differ depending on the resin used, which is determined by the properties of the resin itself. Changing the material, particle size, and particle size distribution of the dry material, as well as the type of resin, will affect the physicochemical properties of the paste, green embryo, or carbon block. In specific implementation, the appropriate dry material, particle size distribution, and resin type should be selected according to the process requirements.

[0094] In some embodiments of this application, the first resin is selected from one or two of thermosetting resins and thermoplastic resins, wherein the thermosetting resin is a modified thermosetting resin or an unmodified thermosetting resin, and the thermoplastic resin is a modified thermoplastic resin or an unmodified thermoplastic resin; preferably, the first resin is selected from one or two or more of phenolic resins, epoxy resins, epoxy-phenolic resins, furan resins, and polyurethane resins. Phenolic resins include, but are not limited to, phenolic resins modified with one or more of lignin, biomass, coal tar, asphalt, graphite, and alkylphenols.

[0095] In some embodiments of this application, the aggregate is aggregate treated with a binder. First, the aggregate is impregnated with a binder and then mixed with a powder paste, which can further reduce the resistivity of the product and improve its conductivity.

[0096] In some embodiments of this application, the aggregate is impregnated in a binder or the aggregate is kneaded with the binder before the powder paste and the aggregate are mixed.

[0097] In some embodiments of this application, before mixing the powder paste and the aggregate, a portion of the aggregate is impregnated in a binder or a portion of the aggregate and the binder are kneaded together, and then mixed with the remaining aggregate. This method can further improve the quality of the product and helps to reduce the amount of binder used.

[0098] In some embodiments of this application, the adhesive is selected from one or more of asphalt, furfural, secondary resin, and lignin.

[0099] In some embodiments of this application, before mixing the powder paste and the aggregate, the aggregate or the aggregate treated with a binder is preheated and mixed to 30-220°C, so that the aggregate particles are evenly distributed and the temperature of the paste is increased rapidly, the mixing time is shortened, the amount of paste adhering to the mixer is reduced, and the "interaction" between the powder paste and the aggregate is accelerated.

[0100] In some embodiments of this application, the powder is selected from one or more of petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrocalcined anthracite.

[0101] In some embodiments of this application, the aggregate is selected from one or more of petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrocalcined anthracite.

[0102] In some embodiments of this application, the dry material is composed of powdered materials of different particle sizes, and is divided into aggregate and powder according to the different particle sizes. The larger particles are aggregate, and the smaller particles are powder. The particle size range for dividing the aggregate and powder is 2 to 0.06 mm, preferably 0.5 to 0.075 mm, and more preferably 0.075 mm, so that the material, quantity, and particle size of the powder match the type and quantity of the resin, thereby achieving the purpose of producing a powder paste that meets the requirements for mixing with the aggregate.

[0103] In some embodiments of this application, particle size refers to the measurement of the size of dry material, commonly expressed in mm, mesh, μm, etc. It can be specifically determined by sieving, that is, the particle size of dry material is classified by sieve, and the dry material is further divided into aggregate and powder. The specifications of the sieve are expressed by the aperture size. The aperture size of a single sieve is consistent. A sieve with an aperture size of 0.075mm is called a sieve with an aperture size of 0.075mm, and so on.

[0104] Particle size less than 0.075mm refers to particles that can pass through a sieve with a 0.075mm aperture during screening, while particle size greater than 0.075mm refers to particles that do not pass through a sieve with a 0.075mm aperture during screening.

[0105] Particle size less than 0.5mm refers to particles that can pass through a sieve with a 0.5mm aperture during screening, while particle size greater than 0.5mm refers to particles that do not pass through a sieve with a 0.5mm aperture during screening.

[0106] In some embodiments of this application, the paste is pressed into paste blocks of regular or irregular shape, and then the paste blocks are added to the aluminum frame of the built-in conductor in the continuous anode aluminum electrolytic cell. The residual heat of the electrolytic cell is used to complete the casting and baking to meet the continuous use requirements of the continuous anode.

[0107] In some embodiments of this application, the weight loss and curing amount of the paste block should be small, preferably zero. Regularly shaped paste blocks are generally in the form of cuboids, cubes, cylinders, spheres, etc., with a single side dimension not exceeding 50cm; irregularly shaped paste blocks are generally particles without a fixed shape, such as particles with a size of 3 to 15cm.

[0108] In some embodiments of this application, the paste is directly added to the upper part of the continuous anode in the continuous anode aluminum electrolytic cell, and the residual heat of the electrolytic cell is used to complete the casting and calcination.

[0109] This application also provides a method for preparing the above-mentioned conductive paste, which includes: kneading the powder and the first resin at a first kneading temperature to obtain a powder paste, wherein the first kneading temperature is controlled within a temperature range where the weight loss of the first resin during kneading is less than or equal to 20% of the total mass of the first resin; and kneading the powder paste and the aggregate at a second kneading temperature to obtain a conductive paste, wherein the second kneading temperature is controlled within a temperature range where the amount of the first resin cured during kneading is less than or equal to 30% of the remaining mass of the first resin.

[0110] This application also provides a conductive preform, which is obtained by molding the above-mentioned conductive paste; preferably, the temperature of the mold used for molding is 50-300℃. The temperature of the paste can be increased before molding, and the heating methods include, but are not limited to, heating with a preheater, heating with a kneader, and heating with a uniform temperature chamber, to further increase the paste temperature and further improve the yield and quality of the preform.

[0111] In some embodiments of this application, the above-mentioned conductive paste can also be subjected to molding treatment, wherein the aluminum part is placed in the mold before molding and then the paste is added to the mold to obtain an aluminum-containing green blank for conductive purposes.

[0112] This application also provides a method for preparing a conductive green embryo, comprising molding the above-mentioned conductive paste to obtain a conductive green embryo; preferably, the temperature of the mold used for molding is 50-300℃. The temperature of the paste can be increased before molding; the heating methods include, but are not limited to, preheating with a preheater, heating with a kneader, and heating with a uniform temperature chamber, to further increase the paste temperature and further improve the yield and quality of the green embryo.

[0113] This application provides a conductive carbon block, which is obtained by calcining the above-mentioned conductive green blanks (including aluminum-containing green blanks); the calcination temperature is 650-1300℃ or the electrolysis temperature. The calcination methods for the green blanks include, but are not limited to, calcination using waste heat from the electrolytic cell or calcination in a dedicated calcination furnace.

[0114] In some embodiments of this application, the above-mentioned conductive green blank (including aluminum-containing green blank) may be cured and / or pre-baked at high temperature, and then the above-mentioned anode block may be bonded to the upper part of the continuous anode in the continuous anode aluminum electrolytic cell, or the above-mentioned green blank may be directly bonded to the upper part of the continuous anode in the continuous anode aluminum electrolytic cell, and the anode may be baked by utilizing the residual heat of the electrolytic cell.

[0115] In some embodiments of this application, the above-mentioned conductive carbon blocks (including aluminum-containing carbon blocks) can also be cast with pig iron and connected to the anode rod and anode steel claw for use on the anode of the aluminum electrolysis cell.

[0116] In some embodiments of this application, the aforementioned conductive carbon block can also be connected to the cathode steel rod via a dovetail groove, pig iron, or cold ramming paste, and used on the cathode of an aluminum electrolysis cell.

[0117] This application also provides a method for preparing the above-mentioned conductive carbon block, which includes calcining the above-mentioned conductive green blank (including aluminum-containing green blank) to obtain the conductive carbon block; preferably, the calcination temperature is 650-1300℃ or the electrolysis temperature. The calcination method for the green blank includes, but is not limited to, calcination using waste heat from the electrolytic cell or calcination in a dedicated calcination furnace.

[0118] Electrolysis temperature: refers to the normal operating temperature of an electrolytic cell (or industrial electric furnace), and is one of the important technical parameters of aluminum electrolysis (electric furnace).

[0119] This application also provides an application of the above-mentioned conductive carbon block in electrolytic aluminum, carbon electrodes, crucibles, and negative electrode plates.

[0120] The particle size in the following examples and comparative examples was determined by sieving, specifically by separating the dry material into aggregate and powder through a sieving process or sieving method.

[0121] Example 1-1

[0122] Weigh out 890 kg of dry material, which includes aggregate and powder. Both aggregate and powder are calcined petroleum coke, with powder particle size less than 0.075 mm and aggregate particle size greater than or equal to 0.075 mm. The dry material consists of 569 kg of aggregate and 321 kg of powder. Also weigh 110 kg of phenolic resin. First, pour the powder and resin (both at 32°C) into a 32°C kneader and knead for 15 minutes. The first kneading temperature is 32°C, and the weight loss of the first resin is 0% of the total weight of the first resin, resulting in a powder paste at 33.9°C. Then, add 569 kg of aggregate (both at 32°C) to the 32°C kneader, and knead for 25 minutes at a second kneading temperature of 32°C. The solidification of the first resin is 0% of the remaining first resin mass, resulting in a paste at 34°C. Vibrate-mold the paste in a 32°C mold. The resulting green body is then cured at 200°C for 10 hours to obtain the desired product. Figure 1 The charcoal block product shown.

[0123] Comparative Example 1-1

[0124] The only difference between Comparative Example 1-1 and Example 1-1 is that the dry material at 32°C was poured into a kneader at 32°C and mixed for 15 minutes. Then, 110 kg of resin at 32°C was added to the kneader and kneaded for 25 minutes to obtain a paste at 33.5°C. The molding method, mold, mold temperature, pressure, and time were the same as in Example 1-1. The resulting green body was cured at 200°C for 10 hours to obtain the desired product. Figure 2 The charcoal block product shown.

[0125] Examples 1-1 and Comparative Examples 1-1 of this application illustrate that the method described in this application can solve the problems of uneven resin distribution, uneven paste composition and texture, low bulk density, and high resistivity in industrial applications. Figure 1 and Figure 2 It was learned that Figure 2 After the charcoal blocks are cured, their outer surface has two long marks from resin flow, a fine crack (marked with a rectangle), and obvious bubbling in 11 locations (marked with circles). Figure 1 After curing, the charcoal blocks showed no signs of resin seepage, bubbling, or small pores on their outer surface. (Explanation) Figure 2 The resin is unevenly distributed in the paste, and the paste texture is also uneven. During the curing process, the areas where the resin is concentrated bubble due to the large amount of volatiles and rapid discharge, forming small pores. Figure 1 Because the resin is evenly distributed in the paste, there is no problem of resin accumulation in a certain part of the carbon block, so there are no bubbles or small pores on the outer surface of the carbon block.

[0126] Meanwhile, following the sampling and determination methods for bulk density and resistivity specified in national standard YS / T 285-2012, we first started from... Figure 1 and 2 Samples 1 and 2, each with dimensions of Φ50×150mm, were taken from the product shown. These samples were then simultaneously placed in an electric furnace under inert gas protection and calcined at 1050℃ for 3 hours. After cooling to room temperature, their bulk densities were measured to be 1.60 g / cm³. 3 and 1.57g / cm 3， The resistivity was measured to be 67 μΩ·m and 88 μΩ·m, respectively.

[0127] Example 2-1

[0128] Weigh 3000g of dry material, which includes aggregate and powder. Both aggregate and powder are calcined petroleum coke, with powder particle size less than 0.5mm and aggregate particle size greater than or equal to 0.5mm. The dry material consists of 1920g of aggregate and 1080g of powder. Also weigh 297g of phenolic resin. First, pour the powder and resin (both at 30℃) into a laboratory kneader 1 at 30℃ and knead for 15 minutes. The first kneading temperature is 30℃, and the weight loss of the first resin is 0% of the total weight of the first resin, resulting in a powder paste at 32.1℃ for later use. Then, add 1920g of preheated aggregate (to 102℃) and the 32.1℃ powder paste to a laboratory kneader 2 at 70℃. The second kneading temperature is 70℃, and knead for 25 minutes. The solidification of the first resin is 0% of the remaining first resin mass, resulting in a paste at 68℃.

[0129] Example 2-2

[0130] The only difference between Example 2-2 and Example 2-1 is that 1920g of aggregate preheated to 102°C and powder paste at 32.1°C were added to a laboratory kneader 2 at 120°C. The second kneading temperature was 120°C, and the kneading was carried out for 25 minutes. The percentage of the first resin cured was 30% of the remaining first resin mass, and a paste at 119°C was obtained. All other conditions were the same.

[0131] Example 2-3

[0132] The only difference between Example 2-3 and Example 2-1 is that 1920g of aggregate preheated to 102°C and powder paste at 32.1°C were added to a laboratory kneader 2 at a temperature of 105°C. The second kneading temperature was 105°C, and the kneading was carried out for 25 minutes. The percentage of the first resin cured was 15% of the remaining first resin mass, and a paste at 104°C was obtained. All other conditions were the same.

[0133] Examples 2-4

[0134] The only difference between Examples 2-4 and Examples 2-3 is that 1920g of room temperature aggregate and a powder paste at 32.1°C were added to a laboratory kneader 2 at 105°C. The second kneading temperature was 105°C, and the kneading time was 30 minutes. The cured amount of the first resin accounted for 15% of the remaining first resin mass, resulting in a paste at 102°C. All other conditions remained the same. In Examples 2-4, because the aggregate was not preheated, the second kneading time was extended to achieve a cured amount of 15% (i.e., the cured amount of the first resin accounted for 15% of the remaining first resin mass).

[0135] Examples 2-5

[0136] The difference between Examples 2-5 and Examples 2-3 is that, after heating the laboratory kneader 2 to 105°C, 1920g of aggregate at 102°C and lignin at 90°C were added to the laboratory kneader and kneaded for 10 minutes. Then, the above-mentioned powder paste at 32.1°C was poured into the laboratory kneader 2, and the second kneading temperature was 105°C for 25 minutes. The percentage of the first resin cured was 15% of the remaining first resin mass, resulting in a paste at 104°C. All other conditions were the same.

[0137] Examples 2-6

[0138] The difference between Examples 2-6 and Examples 2-5 is that, after heating the laboratory kneader 2 to 90°C, 1920g of aggregate at 102°C and lignin at 90°C were added to the laboratory kneader 2 and kneaded for 10 minutes. Then, the above-mentioned powder paste at 32.1°C was poured into the laboratory kneader 2, and the second kneading temperature was 90°C for 25 minutes. The percentage of the first resin cured was 3% of the remaining first resin mass, resulting in a paste at 89°C. All other conditions were the same.

[0139] Examples 2-7

[0140] The difference between Examples 2-7 and Examples 2-6 is that the powder at 80°C and the resin at 30°C are first poured into a laboratory kneader 1 at 80°C and kneaded for 15 minutes. The first kneading temperature is 80°C, and the weight loss of the first resin accounts for 20% of the total mass of the first resin, resulting in a powder paste at 79°C for later use. After heating the temperature of the laboratory kneader 2 to 90°C, 1920g of aggregate at 102°C and lignin at 90°C are added to the laboratory kneader 2 and kneaded for 25 minutes. Then, the powder paste at 79°C is poured into the laboratory kneader 2, and the second kneading temperature is 90°C for 25 minutes. The cured amount of the first resin accounts for 3% of the remaining mass of the first resin. Since the second kneading temperature is 90°C, which is lower than 105°C, the cured amount will be lower than in Examples 2-6, resulting in a paste at 88°C.

[0141] Examples 2-8

[0142] The difference between Examples 2-8 and Examples 2-7 is that the powder at 72°C and the resin at 30°C are first poured into a laboratory kneader 1 at 72°C and kneaded for 15 minutes. The first kneading temperature is 72°C, and the weight loss of the first resin accounts for 10% of the total mass of the first resin, resulting in a powder paste at 70°C. The temperature of the laboratory kneader 2 is then raised to 90°C. 1920g of aggregate at 102°C and lignin at 90°C are added to the laboratory kneader 2 and kneaded for 25 minutes. The powder paste at 70°C is then poured into the laboratory kneader 2, and the second kneading temperature is 90°C. The mixture is kneaded for 25 minutes, and the cured amount of the first resin accounts for 3% of the remaining mass of the first resin, resulting in a paste at 87°C.

[0143] Comparative Example 2-1

[0144] The only difference between Comparative Example 2-1 and Example 2-1 is that the above-mentioned dry material at 30°C was poured into a laboratory kneader at 30°C and mixed for 15 minutes, and then 297g of resin at 30°C was added to the laboratory kneader and kneaded for 25 minutes to obtain a paste at 31.2°C.

[0145] The specifications, models, quantities, and functions of the kneading machines used in this application are not limited. They can be relay kneading, intermittent kneading, or continuous kneading; including but not limited to electric heating kneading machines, gas heating kneading machines, and heat carrier kneading machines. The preparation of powder paste, the kneading of aggregates and binders, the kneading of powder paste and aggregates or kneaded / impregnated aggregates, and the preheating and mixing of aggregates can be carried out at different times in the same kneading machine, or simultaneously or at different times in different kneading machines, or in a system consisting of a group of kneading machines.

[0146] The parameters for Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-2 are shown in Table 1.

[0147] Table 1

[0148]

[0149]

[0150] Example 3-1

[0151] The paste obtained in Example 2-1 was molded in a mold at 180°C to obtain a green sample.

[0152] The molding conditions for Examples 3-2 to 3-8 are the same as those for Example 3-1.

[0153] Comparative Example 3-1

[0154] Take the paste obtained from Comparative Example 2-1 and mold it in a mold at 180℃ to obtain a green sample.

[0155] Comparative Example 3-2

[0156] The paste obtained from Comparative Example 2-1 was molded in a mold at 32°C to obtain a green sample.

[0157] The molding methods of this application include, but are not limited to, extrusion molding, compression molding, vibration molding, and isostatic pressing.

[0158] The parameters of Examples 3-1 to 3-8, and Comparative Examples 3-1 and 3-2 are shown in Table 2.

[0159] Table 2

[0160]

[0161]

[0162] Example 4-1

[0163] Take the conductive green sample from Example 3-1 and place it in an electric furnace under inert gas protection for calcination at 1050°C for 3 hours. After the sample cools to room temperature, a conductive carbon block sample is obtained.

[0164] The calcination conditions for Examples 4-2 to 4-8 and Comparative Example 4-1 are the same as those for Example 4-1.

[0165] The parameters of Examples 4-1 to 4-8 and Comparative Example 4-1 are shown in Table 3.

[0166] Table 3

[0167]

[0168] Experimental Example

[0169] The compressive strength of the green embryo samples from Examples 3-1 to 3-8, and Comparative Examples 3-1 and 3-2 was tested. After the green embryo samples were successfully demolded from the mold, they were cooled at room temperature for 10 minutes, and then their compressive strength was tested on-site using a digital rebound hammer. The results are shown in Table 4.

[0170] Table 4

[0171] embryo compressive strength (MPa) Example 3-1 41 Example 3-2 37 Example 3-3 39 Examples 3-4 39 Examples 3-5 40 Examples 3-6 43 Examples 3-7 42 Examples 3-8 45 Comparative Example 3-1 21 Comparative Example 3-2 0

[0172] The test results of the compressive strength of Comparative Examples 3-1 and 3-2 of this application show that the compressive strength at a molding temperature of 180℃ is higher than that at a molding temperature of 32℃, indicating that the molding method described in this application can improve the compressive strength of the green embryo and help solve the problem of difficult transportation.

[0173] Table 4 shows that the compressive strength of the embodiments in this application is greater than or equal to 37 MPa, which is higher than that of the comparative example. This can solve the problems of low green strength, difficult transportation, and inability to achieve efficient large-scale production and promotion. The technical solution of this application employs two kneading processes and appropriate kneading temperatures, preheating the mixed aggregates, treating the aggregates with a binder, and increasing the molding temperature, all of which can improve the compressive strength. As the first and second kneading temperatures increase, and the aggregates are not treated with a binder, the compressive strength will decrease somewhat, but the temperature increase will not exceed the range specified in the technical solution of this application.

[0174] The bulk density and resistivity of carbon block samples from Examples 4-1 to 4-8 and Comparative Example 4-1 were determined. The bulk density was measured by first processing the sample to the specified dimensions using a sample preparation machine and a cutting machine, then measuring the dimensions with vernier calipers and calculating the volume, then weighing the sample using an electronic balance, and finally calculating the bulk density. The resistivity was measured by placing the prepared sample at the specified position on a carbon block resistivity meter and then measuring the resistivity.

[0175] Table 5

[0176]

[0177]

[0178] Table 5 shows the bulk density and resistivity test results of the embodiments and comparative examples of this application. The bulk density of the embodiments is generally higher than that of the comparative examples, while the resistivity of the embodiments is generally lower than that of the comparative examples. This indicates that this application solves the problems of low bulk density and high resistivity in the prior art. It also proves that reasonable changes in resin composition and partial curing during the manufacturing process are beneficial for efficiently producing high-quality carbon blocks with resin as a binder. The technical solution of this application employs two-stage kneading, preheating of the mixed aggregate, binder treatment of the aggregate, and appropriate first and second kneading temperatures, all of which can increase bulk density while reducing resistivity. As the second kneading temperature increases and the aggregate is not treated with a binder, the bulk density decreases and the resistivity increases. A higher first kneading temperature also increases resistivity, but the temperature increase does not exceed the range specified in the technical solution of this application.

Claims

1. A green body for electric conduction, wherein, Comprise: dry material and first resin, the dry material comprising aggregate and powder, The preparation steps of the green body for conducting electricity are as follows: knead the powder and the first resin at a first kneading temperature to obtain a powder paste, wherein the first kneading temperature is controlled within a temperature range in which the weight loss of the first resin during kneading is less than or equal to 20% of the total mass of the first resin; knead the powder paste and the aggregate at a second kneading temperature to obtain a paste for conducting electricity, wherein the second kneading temperature is controlled within a temperature range in which the solidification amount of the first resin during kneading is less than or equal to 30% of the remaining mass of the first resin; obtain a paste for conducting electricity, the paste for conducting electricity is subjected to a molding process to obtain a green body for conducting electricity; the mold temperature for molding is 180-300℃.

2. The green body for conducting electricity according to claim 1, wherein the first resin is selected from one or both of thermosetting resin and thermoplastic resin.

3. The green body for conducting electricity according to claim 2, wherein the first resin is selected from one or more of phenolic resin, epoxy resin, epoxy phenolic resin, furan resin, and polyurethane resin.

4. The green body for conducting electricity according to claim 1, wherein the aggregate is an aggregate treated with a binder.

5. The green body for conducting electricity according to claim 4, wherein the aggregate is impregnated with a binder or subjected to kneading treatment with the binder before the powder paste and the aggregate are kneaded; or a part of the aggregate is impregnated with a binder or subjected to kneading treatment with the binder before the powder paste and the aggregate are kneaded, and then the remaining part of the aggregate is kneaded.

6. The green body for conducting electricity according to claim 4, wherein the binder is selected from one or more of pitch, furfural, second resin, and lignin.

7. The green body for conducting electricity according to any one of claims 1-6, wherein the aggregate or the aggregate treated with a binder is preheated to 30-220℃ before the powder paste and the aggregate are kneaded.

8. The green body for conducting electricity according to claim 1, wherein the powder is selected from one or more of petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrically calcined anthracite; the aggregate is selected from one or more of petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrically calcined anthracite.

9. The green body for conducting electricity according to claim 1, wherein the dry material is divided into aggregate and powder according to particle size, the aggregate having a large particle size and the powder having a small particle size; wherein the particle size division limit of the aggregate and the powder is 2-0.06mm.

10. The green body for conducting electricity according to claim 9, wherein the particle size division limit of the aggregate and the powder is 0.5-0.075mm.

11. The green body for conducting electricity according to claim 10, wherein the particle size division limit of the aggregate and the powder is 0.075mm.

12. The green body for conductive use according to claim 1, wherein the paste is pressed to form a paste block with regular shape or irregular shape.

13. A method for preparing a green body for conducting electricity, comprising the following: mixing the powder and the first resin at a first kneading temperature to obtain a powder paste, wherein the first kneading temperature is controlled in a range that the weight loss of the first resin during the mixing is less than or equal to 20% of the total weight of the first resin; mixing the powder paste and the aggregate at a second kneading temperature to obtain a paste for conducting electricity, wherein the second kneading temperature is controlled in a range that the solidification of the first resin during the mixing is less than or equal to 30% of the remaining weight of the first resin; and the paste for conducting electricity is subjected to a molding process to obtain a green body for conducting electricity; the mold temperature for the molding is 180-300℃.

14. The method according to claim 13, wherein the first resin is selected from one or both of thermosetting resin and thermoplastic resin.

15. The method according to claim 14, wherein the first resin is selected from one or two or more of phenolic resin, epoxy resin, epoxy-phenolic resin, furan resin, and polyurethane resin.

16. The method according to claim 13, wherein the aggregate is an aggregate treated with a binder.

17. The method according to claim 16, wherein the aggregate is impregnated with the binder or the aggregate and the binder are subjected to a kneading process before the powder paste and the aggregate are mixed; or a part of the aggregate is impregnated with the binder or a part of the aggregate and the binder are subjected to a kneading process, and then the remaining part of the aggregate is mixed.

18. The method according to claim 16, wherein the binder is selected from one or two or more of pitch, furfural, second resin, and lignin.

19. The method according to any one of claims 13-18, wherein the aggregate or the binder-treated aggregate is preheated to 30-220℃ before the powder paste and the aggregate are mixed.

20. The method according to claim 13, wherein the powder is selected from one or two or more of petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrically calcined anthracite; and the aggregate is selected from one or two or more of petroleum coke, pitch coke, calcined petroleum coke, calcined pitch coke, biomass, graphite, and electrically calcined anthracite.

21. The method according to claim 13, wherein the dry material is divided into aggregate and powder according to the particle size, and the aggregate has a larger particle size and the powder has a smaller particle size; wherein the particle size range for dividing the aggregate and the powder is 2-0.06mm.

22. The method according to claim 21, wherein the particle size dividing limit for the aggregate and the powder is 0.5-0.075mm.

23. The method according to claim 22, wherein the particle size dividing limit for the aggregate and the powder is 0.075mm.

24. The method of claim 13, wherein, the paste is subjected to a pressing process to obtain a paste block with regular or irregular shape.

25. A carbon block for conducting electricity, wherein the green body for conducting electricity according to any one of claims 1-12 or the green body for conducting electricity prepared by the method according to any one of claims 13-22 is subjected to a baking process to obtain the carbon block for conducting electricity.

26. The carbon block for conducting electricity according to claim 25, wherein, the baking temperature is 650-1300°C.

27. A method for preparing a carbon block for conducting electricity, comprising, baking the green compact for conducting electricity according to any one of claims 1-12 or prepared by the method according to any one of claims 13-22 to obtain a carbon block for conducting electricity.

28. The method for preparing according to claim 27, wherein, the baking temperature is 650-1300°C.

29. Use of the carbon block for conducting electricity according to claim 25 or 26 or prepared by the method according to claim 27 or 28 in electrolytic aluminum, carbonaceous electrode, sagger, negative plate.

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