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 2020-12-31 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：将改性沥青和石油焦进行混捏,得到的产物进行焙烧,以得到预焙阳极；其中,所述改性沥青的喹啉不溶物值为15-19；所述改性沥青和所述石油焦的重量比为1：8-12。采用该方法制备得到的预焙阳极能够达到提高残极率(即残极率≥85wt％)与不降低其他参数的最佳平衡,其他参数不低于现有技术,适应性广。(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 the modified asphalt and the petroleum coke to obtain a product, and roasting the product to obtain a prebaked anode; wherein the quinoline insoluble value of the modified asphalt is 15-19; the weight ratio of the modified asphalt to the petroleum coke is 1: 8-12. The prebaked anode prepared by the method can achieve the optimal balance of improving the anode scrap rate (namely the anode scrap rate is more than or equal to 85 wt%) and not reducing other parameters, and the other parameters are not lower than those of the prior art, so that the method has wide adaptability.)

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

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

wherein the quinoline insoluble value of the modified asphalt is 15-19; the weight ratio of the modified asphalt to the petroleum coke is 1: 8-12.

2. The method of claim 1, wherein the modified asphalt is obtained by modifying asphalt by adding a modifier A and an optional modifier B;

preferably, when the quinoline insoluble value of the asphalt is less than or equal to 5, the asphalt is modified by adding a modifier A and a modifier B; the weight ratio of the asphalt to the modifier A to the modifier B is 1: 0.2-0.4: 0.1-0.2;

when the quinoline insoluble value of the asphalt is more than 5 and less than 15, the asphalt is modified by adding a modifier A; the weight ratio of the asphalt to the modifier A is 1: 0.1-0.5.

3. The process of claim 2, 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-.

4. The process according to claim 2 or 3, wherein the modifier A is an acidic substance;

preferably, the acidic substance is selected from at least one of oleic acid, boric acid, tartaric acid and ammonium dihydrogen phosphate.

5. The process of any one of claims 2-4, wherein the modifier B is an aluminum-containing compound;

preferably, the modifier B is selected from at least one of aluminum sulfate, aluminum hydroxide, aluminum fluoride and aluminum chloride.

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 from room temperature 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 of claim 8, wherein the prebaked anode has a residual anode ratio of 85 wt% or more, a resistivity of 55 μ Ω · m or less, and a thermal expansion coefficient of 5 x 10 or less^-6K, compressive strength is more than or equal to 32MPa, and the true density is more than or equal to 2.04g/cm³The apparent density is more than or equal to 1.53g/cm³Ash content is less than or equal to 0.5 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 anode is used as an anode material in a prebaked aluminum electrolytic cell. In the prior art, petroleum coke and asphalt coke are generally used as aggregates, and coal pitch is used as a binder. This carbon block has been calcined and has a stable geometry, so it is also called a prebaked anode carbon block, and is also conventionally called a carbon anode for aluminum electrolysis. An aluminum electrolytic cell using prebaked anode carbon blocks as anodes is called a prebaked anode electrolytic cell, called a prebaked cell for short, and is a modern large-scale aluminum electrolytic cell.

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 properties: 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%.

The different reactivities of pitch coke and petroleum coke can lead to pitch coke phase selective oxidation reaction, reduce the intensity that pitch coke and petroleum coke link the structure, lead to the increase of the surface area of pitch coke like this, orderly organizational structure is less, its reactivity with the air is higher than the reactivity of petroleum coke and air, when prebaked anode high temperature electrolysis, preferential oxidation pitch coke makes thick and thick petroleum coke protruding in the anode surface, one of them part reaches to drop by self quality after the certain degree, form the charcoal sediment, cause prebaked anode excessive consumption.

Therefore, there is still a need for improvement in the technique for preparing prebaked anodes.

Disclosure of Invention

The invention aims to overcome the technical problems of easy oxidation and insufficient mechanical strength 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 through experiments that during electrolysis, the prebaked anode needs to ensure good oxidation resistance and has enough mechanical strength to stabilize the normal operation of electrolysis, and the inventor bakes the obtained product by selecting the modified asphalt with the quinoline insoluble value of 15-19 as the raw material and kneading the modified asphalt and petroleum coke, so that the prebaked anode can achieve the optimal balance of improving the anode scrap rate and not reducing other parameters.

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 the modified asphalt and the petroleum coke to obtain a product, and roasting the product to obtain a prebaked anode;

wherein the quinoline insoluble value of the modified asphalt is 15-19; the weight ratio of the modified asphalt to the petroleum coke is 1: 8-12.

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.

The method for preparing the prebaked anode provided by the invention selects the modified asphalt with the quinoline insoluble value of 15-19 and the petroleum coke as raw materials, wherein the weight ratio of the modified asphalt to the petroleum coke is controlled to be 1: 8-12, kneading the modified asphalt and the petroleum coke, roasting the obtained product, and obtaining the prebaked anode which can achieve the best balance of improving the anode scrap rate (namely, the anode scrap rate is more than or equal to 85 wt%) and not reducing other parameters, wherein the other parameters are not lower than the prior art, and the prebaked anode has wide adaptability.

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 one aspect, the present invention provides a method of preparing a prebaked anode, the method comprising:

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

wherein the quinoline insoluble value of the modified asphalt is 15-19; the weight ratio of the modified asphalt to the petroleum coke is 1: 8-12.

In some embodiments of the present invention, the modified asphalt is asphalt modified by adding modifier a and optionally modifier B. When the quinoline insoluble value of the asphalt is less than or equal to 5, the asphalt is modified by adding a modifier A and a modifier B; the weight ratio of the asphalt to the modifier A to the modifier B is 1: 0.2-0.4: 0.1-0.2. When the quinoline insoluble value of the asphalt is more than 5 and less than 15, the asphalt is modified by adding a modifier A; the weight ratio of the asphalt to the modifier A is 1: 0.1-0.5. By modifying the asphalt, the improvement of the CO of the prebaked anode can be realized₂Reactivity is optimally balanced with no reduction in other parameters.

In the invention, in order to realize the modification of the asphalt, the modification conditions comprise: the temperature of modification is preferably 165-185 ℃, and stirring is carried out for 2-4h after shearing is carried out for 15-20min at the rotating speed of 2950-2970 r/min.

In some embodiments of the present invention, preferably, 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 modifier a is an acidic material. Preferably, the acidic substance is selected from at least one of oleic acid, boric acid, tartaric acid and ammonium dihydrogen phosphate.

In some embodiments of the invention, the modifier B is an aluminum-containing compound. Preferably, the modifier B is selected from at least one of aluminum sulfate, aluminum hydroxide, aluminum fluoride and aluminum chloride.

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.

In some embodiments of the present invention, preferably, the roasting conditions include: heating from room temperature 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 present invention, it is preferable that the prebaked anode has a stub rate of 85 wt% or more, a resistivity of 55 μ Ω · m or less, and a thermal expansion coefficient of 5 × 10 or less^-6K, compressive strength is more than or equal to 32MPa, and the true density is more than or equal to 2.04g/cm³The apparent density is more than or equal to 1.53g/cm³Ash content is less than or equal to 0.5 wt%.

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

In the present invention, the anode scrap rate: is to characterize the prebaked anode CO₂The 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 quinoline insoluble content of the asphalts used in the examples and comparative examples, the amounts of modifier A and modifier B, and the quinoline insoluble content of the modified asphalts are shown in Table 2.

TABLE 2

Example 1

(1) Modifying asphalt according to the proportion shown in Table 2, wherein the modification temperature is 175 ℃, shearing is carried out at the rotating speed of 2955r/min for 20min, and stirring is carried out for 2h, so as to obtain modified asphalt;

(2) crushing petroleum coke to a particle size of 1-3mm, mixing the crushed petroleum coke and modified asphalt according to a weight ratio of 8:1, then loading the mixed raw material into an electric heating kneading machine, kneading at a temperature of 120 ℃, and vibrating for 5 min;

(3) 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 2

(1) Modifying asphalt according to the proportion shown in Table 2, wherein the modification temperature is 165 ℃, shearing is carried out at the rotating speed of 2955r/min for 15min, and stirring is carried out for 3h, so as to obtain modified asphalt;

(2) crushing petroleum coke to a particle size of 1-3mm, mixing the crushed petroleum coke and modified asphalt according to a weight ratio of 12:1, then loading the mixed raw material into an electric heating kneading machine, kneading at a temperature of 150 ℃, and vibrating for 8 min;

(3) roasting the kneaded material in a tunnel kiln, raising the temperature to 1150 ℃ from the initial temperature of 20 ℃ at 1 ℃/min, and carrying out heat preservation roasting for 90 hours to obtain the prebaked electrode.

Example 3

(1) Modifying asphalt according to the proportion shown in Table 2, wherein the modification temperature is 180 ℃, shearing is carried out at the rotating speed of 2968r/min for 18min, and stirring is carried out for 4h, so as to obtain modified asphalt;

(2) crushing petroleum coke to a particle size of 1-3mm, mixing the crushed petroleum coke and modified asphalt according to a weight ratio of 10:1, then loading the mixed raw material into an electric heating kneading machine, kneading at a temperature of 130 ℃, and vibrating for 6 min;

(3) 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.

Examples 4 to 8

Prebaked electrodes were prepared in the same manner as in example 1, except that the modification of the pitch was carried out in accordance with the parameters shown in Table 2.

Examples 9 to 10

Prebaked electrodes were prepared in the same manner as in example 1, except that no modification of the pitch was required, and the raw material parameters are shown in tables 1 and 2.

Comparative example 1

A prebaked electrode was prepared by following the procedure of example 1, except that the quinoline insoluble content of the pitch was 5, and no modification was made to the pitch.

Comparative example 2

A prebaked electrode was prepared by following the procedure of example 1, except that the quinoline insoluble content of the pitch was 20, and no modification was made to the pitch.

Comparative example 3

A prebaked electrode was prepared as in example 1, except that the weight ratio of petroleum coke to modified asphalt was 15:1

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 1, examples 1 to 10 can use the technical solution of the present invention to make the quinoline insoluble value of the asphalt 15 to 19; the weight ratio of the modified asphalt to the petroleum coke is 1: 8-12, the residual anode rate of the obtained prebaked anode is improved, and the optimal balance without reducing other parameters is realized. In contrast, in comparative examples 1 to 3, the technical scheme of the present invention was not adopted, and the obtained prebaked anode had a low anode scrap rate, and the optimum balance without lowering other parameters could not be achieved.

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.