阅读说明：本技术 预焙阳极及其制备方法和应用 (Prebaked anode, and preparation method and application thereof ) 是由 孙占龙 赵宝龙 于 2021-01-11 设计创作，主要内容包括：本发明涉及电解领域,公开了预焙阳极及其制备方法和应用,该方法包括：将沥青、石油焦和添加剂进行混捏,得到的产物进行焙烧,以得到预焙阳极；其中,所述添加剂为碳素添加剂A和/或有机添加剂B；所述沥青、所述石油焦和所述添加剂的重量比为1：5-9：0.1-0.5。该方法中,通过沥青、石油焦和添加剂的协同作用,能够克服现有技术中预焙阳极的强度低,电阻率高的技术问题,并且,拓宽了沥青的选择范围。(The invention relates to the field of electrolysis, and discloses a prebaked anode and a preparation method and application thereof, wherein the method comprises the following steps: kneading asphalt, petroleum coke and an additive to obtain a product, and roasting the product to obtain a prebaked anode; wherein the additive is a carbon additive A and/or an organic additive B; the weight ratio of the asphalt, the petroleum coke and the additive is 1: 5-9: 0.1-0.5. In the method, the technical problems of low strength and high resistivity of the prebaked anode in the prior art can be solved through the synergistic effect of the asphalt, the petroleum coke and the additive, and the selection range of the asphalt is widened.)

1. A method of making a prebaked anode, comprising:

kneading asphalt, petroleum coke and an additive to obtain a product, and roasting the product to obtain a prebaked anode;

wherein the additive is a carbon additive A and/or an organic additive B; the weight ratio of the asphalt, the petroleum coke and the additive is 1: 5-9: 0.1-0.5.

2. The method of claim 1, wherein the weight ratio of the asphalt, the petroleum coke, and the additive is 1: 6.8-8: 0.15-0.45.

3. The process according to claim 1 or 2, wherein the pitch has a β value < 20, the additive is selected from carbon additives a, and the weight ratio of the additive to the pitch is from 0.1 to 0.3: 1;

and/or the beta value of the asphalt is more than or equal to 20 and less than or equal to 25, the additive is selected from a carbon additive A and an organic additive B, and the weight ratio of the carbon additive A to the organic additive B to the asphalt is 0.05-0.15: 0.05-0.15: 1;

and/or the asphalt has a beta value >25, the additive is selected from organic additives B, and the weight ratio of the organic additives B to the asphalt is 0.3-0.5: 1.

4. the method of any one of claims 1-3, wherein the carbon additive A is selected from at least one of acetylene black, pebble milling, and graphite powder;

and/or the organic additive B is selected from at least one of anthracene oil, tar oil and acidified oil.

5. The process according to any one of claims 1 to 4, wherein the pitch is coal tar pitch and/or petroleum pitch;

preferably, the asphalt has an ash content of 0.1-0.3 wt%, a volatile matter content of 50-55 wt%, a sulfur content of 0.5-0.7 wt%, a softening point of 100-.

6. The process according to any one of claims 1-5, wherein the process further comprises pre-comminuting the petroleum coke to obtain comminuted petroleum coke;

preferably, the particle size of the crushed petroleum coke is 1-3 mm;

preferably, the ash content of the petroleum coke is 0.2-0.4 wt%, the volatile matter content is 0.5-0.7 wt%, the sulfur content is 1-1.8 wt%, and the true density is more than or equal to 2.05g/cm³The resistivity was 400-500. mu. omega. m.

7. The method of any of claims 1-6, wherein the kneading conditions comprise: the temperature is 120 ℃ and 150 ℃, and the time is 4-8 min.

Preferably, the conditions of the calcination include: heating to 1100-1150 ℃ at a speed of 0.5-1 ℃/min, and then preserving the heat for 80-95 h.

8. A prebaked anode produced by the method according to any one of claims 1 to 7.

9. The prebaked anode according to claim 8, wherein the anode scrap rate of the prebaked anode is 80 wt% or more; the resistivity is less than or equal to 50 mu omega m; a coefficient of thermal expansion of 4-5X 10^-6K; the compressive strength is more than or equal to 38 MPa; the true density is 2.05-2.12g/cm³(ii) a The apparent density is 1.53-1.6g/cm³(ii) a Ash content 0.4-0.45 wt%.

10. Use of a prebaked anode according to claim 8 or 9 for the electrolysis of aluminum.

Technical Field

The invention relates to the field of electrolysis, in particular to a prebaked anode and a preparation method and application thereof.

Background

The prebaked carbon anode is usually installed in the upper part of the electrolytic cell, and a strong direct current of 60-300ka is introduced into the electrolyte through the carbon anode. At the portion of the bottom of the carbon anode that contacts the molten electrolyte, a complex electrochemical reaction (anodic reaction) occurs that decomposes alumina. In the presence of carbon, the anode end products are CO and CO₂. In the aluminum electrolysis production, the daily average consumption of the carbon anodes is 1-2cm, and the main content of the anode work is to regularly add new anode paste (for a self-baking anode electrolytic cell) to the upper part of the electrolytic cell or regularly replace the pre-baking anodes (for a pre-baking anode electrolytic cell) so as to keep the continuous and normal work of the anodes.

In the prior art, the calcined petroleum coke is generally used to be matched with asphalt to prepare the prebaked anode, and the prepared prebaked anode can achieve the following performance: apparent density is more than or equal to 1.53g/cm³The true density is more than or equal to 2.04g/cm³Compressive strength is more than or equal to 32MPa, residual anode rate is more than or equal to 80 wt%, room-temperature resistivity is less than or equal to 55 mu omega.m, and thermal expansion coefficient is less than or equal to 5 multiplied by 10^-6K, ash content is less than or equal to 0.5 wt%. However, in the production of metal aluminum electrolysis, the resistivity of the prebaked anode is required to be infinitely close to zero, and the higher the compressive strength is, the more beneficial the production is, and the prebaked anode obtained by the prior art still has the technical problems of lower strength and higher resistivity.

Therefore, it is still necessary to explore the technology of prebaked anodes.

Disclosure of Invention

The invention aims to overcome the technical problems of low strength and high resistivity of a prebaked anode in the prior art, and provides the prebaked anode and a preparation method and application thereof.

The inventor of the invention finds in experiments that the beta component plays a main role in binding and filling pores in dry materials in asphalt, and within a certain range, the higher the content of the beta component is, the better the caking property of coal asphalt is, the better the coking performance is, the pore wall is dense, the generated structure is fibrous, and the prepared prebaked anode has high compressive strength and small resistance; however, when the content of the β component in the asphalt exceeds the critical point, the compressive strength is rather lowered, and when kneading, the asphalt cannot be uniformly distributed among the dry particles, and the permeation of the asphalt binder into the pores of the dry particles is also inhibited, and during baking, the electrode is deformed, cracks are generated, the strength is lowered, and the resistivity is raised. Therefore, to achieve the goal of balancing the resistance and the strength value, the β value of the pitch can only be fixed at the above critical point, i.e., in the range of 20-25%, and the strength and resistance values are fixed when the range is reached.

Therefore, a better index cannot be obtained only by screening the beta component content of the asphalt, and the selection range of the asphalt (only the asphalt with the beta value of 20-25 percent can be selected) is smaller. Therefore, the inventor can overcome the technical problems of low strength and high resistivity of the prebaked anode in the prior art by adding the additive into the asphalt and the petroleum coke, and widens the selection range of the asphalt.

In order to achieve the above object, a first aspect of the present invention provides a method of preparing a prebaked anode, the method comprising:

kneading asphalt, petroleum coke and an additive to obtain a product, and roasting the product to obtain a prebaked anode;

wherein the additive is a carbon additive A and/or an organic additive B; the weight ratio of the asphalt, the petroleum coke and the additive is 1: 5-9: 0.1-0.5.

In a second aspect, the invention provides a prebaked anode produced by the above method.

A third aspect of the invention provides the use of a prebaked anode as described above in the electrolysis of aluminium.

According to the method for preparing the prebaked anode, the additive is added into the asphalt and the petroleum coke, the additive is a carbon additive A and/or an organic additive B, and the weight ratio of the asphalt to the petroleum coke to the additive is controlled to be 1: 5-9: 0.1-0.5, can overcome the technical problems of low strength and high resistivity of the prebaked anode in the prior art through the synergistic action of the asphalt, the petroleum coke and the additive, and broadens the selection range of the asphalt.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In a first aspect the present invention provides a method of making a prebaked anode, the method comprising:

kneading asphalt, petroleum coke and an additive to obtain a product, and roasting the product to obtain a prebaked anode;

wherein the additive is a carbon additive A and/or an organic additive B; the weight ratio of the asphalt, the petroleum coke and the additive is 1: 5-9: 0.1-0.5.

In some embodiments of the invention, the weight ratio of the bitumen, the petroleum coke and the additive is preferably 1: 6.8-8: 0.15-0.45.

In the present invention, the β component refers to a component insoluble in toluene but soluble in quinoline in the asphalt, and is equal to the difference between the toluene-insoluble BI and the quinoline-insoluble QI in the content (i.e., β value). The beta component plays a main role in binding and filling pores in dry materials in the asphalt, the higher the content of beta resin is, the better the binding property of the coal asphalt is, the good coking performance is, the pore wall is dense, the generated structure is fibrous, and the prepared prebaked anode has high compressive strength and small resistance. However, when the content of the β resin in the asphalt is too high, the compressive strength is rather lowered because the viscosity of the asphalt is too high at this time, and the asphalt is not uniformly distributed among the dry particles at the time of kneading, and the asphalt binder is prevented from penetrating into the pores of the dry particles, and the electrode is deformed at the time of firing to cause cracks, thereby lowering the strength.

In some embodiments of the present invention, in order to further improve the strength, reduce the electrical resistance, and expand the selection range of the asphalt as much as possible, other additives are added to achieve the effect of the beta value of the impact asphalt on the anode strength and electrical resistance, and the type and amount of the additives are determined according to the beta value of the asphalt, and the additives are carbon additives a and/or organic additives B. Specifically, the inventors have found that carbon additive a can reduce electrical resistance and organic additive B can increase permeability of the asphalt.

In some embodiments of the invention, preferably the pitch has a beta value < 20, the additive is selected from carbon additives a, and the weight ratio of the additive to the pitch is from 0.1 to 0.3: 1.

further preferably, the beta value of the asphalt is more than or equal to 20 and less than or equal to 25, the additive is selected from a carbon additive A and an organic additive B, and the weight ratio of the carbon additive A to the organic additive B to the asphalt is 0.05-0.15: 0.05-0.15: 1.

further preferably, the asphalt has a beta value >25, the additive is selected from organic additives B, and the weight ratio of the organic additives B to the asphalt is from 0.3 to 0.5: 1.

in some embodiments of the present invention, preferably, the carbon additive a is selected from at least one of acetylene black, nodular graphite powder, and graphite powder.

In some embodiments of the present invention, preferably, the organic additive B is selected from at least one of anthracene oil, tar oil and acidified oil. Wherein the coker oil may be at least one selected from coal tar, wood tar and pine tar. The acidified oil may be at least one selected from swill oil, swill oil and soapstock.

In some embodiments of the invention, the pitch is coal tar pitch and/or petroleum pitch.

In some embodiments of the present invention, to ensure the caking property and coking property of the asphalt, the ash content of the asphalt is preferably 0.1 to 0.3 wt%, the volatile component is preferably 50 to 55 wt%, the sulfur content is preferably 0.5 to 0.7 wt%, the softening point is preferably 100-.

In some embodiments of the invention, the method further comprises pre-comminuting the petroleum coke to obtain comminuted petroleum coke. Preferably, the particle size of the crushed petroleum coke is 1-3 mm.

In some embodiments of the present invention, to ensure the yield of the prebaked anode, the ash content of the petroleum coke is preferably 0.2-0.4 wt%, the volatile component is preferably 0.5-0.7 wt%, the sulfur content is preferably 1-1.8 wt%, and the true density is preferably ≥ 2.05g/cm³The resistivity is preferably 400-500. mu. omega. m.

In some embodiments of the invention, the kneading conditions comprise: the kneading temperature is preferably 120-150 ℃. The kneading time is preferably 4 to 8 min. The kneading condition can ensure that the asphalt and the coal aggregate are fully mixed and bonded.

In some embodiments of the present invention, preferably, the roasting conditions include: heating to 1100-1150 ℃ at a speed of 0.5-1 ℃/min, and then preserving the heat for 80-95 h. The present invention does not limit the baking equipment as long as the purpose of baking can be achieved, and examples thereof include tunnel kiln, annular kiln, and baking pot.

In a second aspect, the invention provides a prebaked anode produced by the above method.

In some embodiments of the invention, the anode scrap rate of the prebaked anode is preferably 80 wt% or more; the resistivity is less than or equal to 50 mu omega m; a coefficient of thermal expansion of 4-5X 10^-6K; the compressive strength is more than or equal to 38 MPa; the true density is 2.05-2.12g/cm³(ii) a The apparent density is 1.53-1.6g/cm³(ii) a Ash content 0.4-0.45 wt%.

A third aspect of the invention provides the use of a prebaked anode as described above in the electrolysis of aluminium.

In the invention, the anode scrap rate is used for representing the CO of the prebaked anode₂The indices of reactivity and air reactivity, the prebaked anode material is not homogeneous in terms of its chemical reactivity, some of the more active particles will undergo selective oxidation, while the less active particles will be shed into the electrolyte, CO₂The reactivity and air reactivity directly determine the carbon consumption of the prebaked anode.

In the present invention, Quinoline Insolubles (QI) refer to components insoluble in quinoline, including primary quinoline insolubles and secondary quinoline insolubles. The secondary QI is the product of the polymerization of aromatic hydrocarbon compound molecules in the asphalt at a given temperature, and has a C/H greater than 3.5. Bitumen secondary QI has both a beneficial and an adverse effect as a binder in the production of electrode articles. The adverse effect is that the bitumen demand increases with increasing secondary QI content, and the beneficial effect is that the oxidative consumption of the electrode and carbon product decreases with increasing secondary QI content.

The present invention will be described in detail below by way of examples. In the examples and comparative examples, the properties of the asphalt and petroleum coke in the raw materials are shown in table 1.

TABLE 1

The beta values of the pitches used in the examples and comparative examples, and the kinds and amounts of the carbon additive A and the organic additive B are shown in Table 2.

TABLE 2

Example 1

(1) Crushing petroleum coke to a particle size of 1-3mm, mixing the crushed petroleum coke, asphalt and additives according to the proportion shown in table 2, then loading the mixed raw materials into an electric heating kneading machine, kneading at the temperature of 130 ℃, and vibrating for 6 min;

(2) roasting the kneaded material in a tunnel kiln, heating to 1125 ℃ at 1 ℃/min from the initial temperature of 20 ℃, and carrying out heat preservation roasting for 95h to obtain the prebaked electrode.

Example 2

(1) Crushing petroleum coke to a particle size of 1-3mm, mixing the crushed petroleum coke, asphalt and additives according to the proportion shown in table 2, then loading the mixed raw materials into an electric heating kneading machine, kneading at the temperature of 120 ℃, and vibrating for 5 min;

(2) roasting the kneaded material in a tunnel kiln, heating the kneaded material to 1100 ℃ from the initial temperature of 20 ℃ at the speed of 0.5 ℃/min, and carrying out heat preservation roasting for 80 hours to obtain the prebaked electrode.

Example 3

(1) Crushing petroleum coke to a particle size of 1-3mm, mixing the crushed petroleum coke, asphalt and additives according to the proportion shown in table 2, then loading the mixed raw materials into an electric heating kneading machine, kneading at the temperature of 120 ℃, and vibrating for 5 min;

(2) roasting the kneaded material in a tunnel kiln, heating the kneaded material to 1100 ℃ from the initial temperature of 20 ℃ at the speed of 0.5 ℃/min, and carrying out heat preservation roasting for 80 hours to obtain the prebaked electrode.

Examples 4 to 7

Prebaked electrodes were prepared by following the procedure of example 1 except that the kinds and amounts of additives were changed according to the β values of the pitches in accordance with the parameters shown in table 2.

Examples 8 to 9

Prebaked electrodes were prepared in the same manner as in example 1, except that the experiment was carried out in the proportions of petroleum coke, pitch and additives shown in Table 2.

Comparative example 1

A prebaked electrode was prepared by following the procedure of example 1 except that no additive was added.

Comparative example 2

A prebaked electrode was prepared according to the method of example 1, except that the weight ratio of petroleum coke, pitch and additives was 1: 3: 0.6.

test example

CO of prebaked anodes obtained in examples and comparative examples₂The reactivity was measured according to the specification of YS/T63.12.

The resistivities of the prebaked anodes obtained in examples and comparative examples were measured according to the specification of YS/T63.2.

The coefficients of thermal expansion of the prebaked anodes obtained in examples and comparative examples were measured in accordance with the specification of YS/T63.4.

The compressive strength of the prebaked anodes obtained in examples and comparative examples was measured in accordance with the specification of YS/T63.15.

The true densities of the prebaked anodes obtained in examples and comparative examples were measured according to the specification of YS/T63.9.

The apparent densities of the prebaked anodes obtained in examples and comparative examples were measured in accordance with the specification of YS/T63.7.

The ash content of the prebaked anodes obtained in examples and comparative examples was measured according to the specification of YS/T63.19.

The above test results are shown in table 3.

TABLE 3

As can be seen from the results in table 3, in examples 1 to 9, the asphalt, petroleum coke and the additive are mixed in a weight ratio of 1: 5-9: 0.1-0.5, wherein the additive is carbon additive A and/or organic additive B, and the obtained prebaked anode has high strength and low resistivity through the synergistic effect of asphalt, petroleum coke and the additive. The technical scheme of the invention is not adopted in the comparative examples 1-2, and the obtained prebaked anode has low strength and high resistivity.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.