Method for preparing carbon anode by using low-quality petroleum coke

Abstract

The application discloses a method for preparing carbon anodes by using inferior petroleum coke. According to the differences in the contents of sulfur and vanadium in the petroleum coke, the raw materials are divided into high-sulfur high-vanadium petroleum coke, high-sulfur low-vanadium petroleum coke and low-sulfur low-vanadium petroleum coke, and are respectively subjected to differential calcination at different temperatures. After the calcination, the petroleum coke is crushed and sieved, and is functionally formulated according to the particle size, wherein the high-sulfur low-vanadium petroleum coke is used for constructing an anode skeleton, the high-sulfur high-vanadium petroleum coke is used in the form of fine powder to participate in the baking stage and the synergistic shrinkage of coal pitch, and the remaining particle size adopts the low-sulfur low-vanadium petroleum coke. After the formulation, the coal pitch is mixed and kneaded to be formed and baked, so that the carbon anode is prepared. Under the condition of blending and using the high-sulfur high-vanadium petroleum coke, the method can make the contents of sulfur and vanadium in the finished carbon anode meet the industrial use requirements, and can ensure that the physical and chemical properties of the finished carbon anode, such as air reactivity and resistivity, reach the level of traditional high-quality carbon anodes.

Description

Technical Field

[0001] This invention relates to the field of carbon material preparation technology, and specifically to a method for preparing anodes using low-quality petroleum coke. Background Technology

[0002] Due to the global trend towards heavier crude oil and adjustments in refining processes, high-quality, low-sulfur, and low-vanadium petroleum coke resources are becoming increasingly scarce and their prices are continuing to rise. To ensure production continuity and control costs, blending high-sulfur and high-vanadium inferior petroleum coke with high-quality coke has become the norm in aluminum electrolytic anode production.

[0003] Existing technologies often employ a uniform calcination process after blending. This process struggles to accommodate the calcination characteristics of different petroleum cokes. High-vanadium petroleum coke, when calcined at high temperatures, exposes the active sites of vanadium oxides, leading to increased anode air reactivity. Conversely, high-sulfur petroleum coke, due to insufficient calcination, results in increased anode resistivity. Furthermore, this uniform calcination process causes inconsistent shrinkage behavior of the anode during roasting, leading to increased anode porosity and poor structural stability.

[0004] Therefore, developing a process that enables the utilization of low-quality petroleum coke resources while ensuring that the physical and chemical properties of the finished anode reach the level of traditional high-quality anodes has significant economic value and industrial application significance. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing carbon anodes with differentiated calcination and particle-scale functionalized ingredients, ensuring that the finished anodes achieve the level of traditional high-quality anodes in terms of air reactivity, resistivity and other physicochemical properties.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] One objective of this invention is to provide a method for preparing carbon anodes using low-quality petroleum coke, the steps of which are as follows:

[0008] S1. Based on the differences in sulfur and vanadium content in petroleum coke, the raw materials are divided into three categories: high-sulfur and high-vanadium petroleum coke, high-sulfur and low-vanadium petroleum coke, and low-sulfur and low-vanadium petroleum coke.

[0009] S2. Differentiately calcine the above three types of petroleum coke;

[0010] S3. The calcined petroleum coke is crushed and screened, and then batched according to particle size functionalization.

[0011] S4. Mix the above ingredients with coal tar pitch, knead and shape to make a raw anode;

[0012] S5. The green anode is roasted.

[0013] Further, in S1, the high-sulfur, high-vanadium petroleum coke is petroleum coke with a sulfur content >4wt% and a vanadium content >400ppm; the high-sulfur, low-vanadium petroleum coke is petroleum coke with a sulfur content >4wt% and a vanadium content <200ppm; and the low-sulfur, low-vanadium petroleum coke is petroleum coke with a sulfur content <2wt% and a vanadium content <200ppm.

[0014] Furthermore, in S2, the differentiated calcination specifically refers to the high-sulfur, high-vanadium petroleum coke being calcined at 950–1050°C.

[0015] Preferably, the high-sulfur, low-vanadium petroleum coke is calcined at 1300°C.

[0016] Furthermore, in S2, the differentiated calcination specifically refers to calcining high-sulfur, low-vanadium petroleum coke at 1250–1350°C.

[0017] Preferably, the high-sulfur, low-vanadium petroleum coke is calcined at 1300°C.

[0018] Furthermore, the differentiated calcination described in S2 specifically refers to the calcination of low-sulfur, low-vanadium petroleum coke at 1150–1250°C.

[0019] Preferably, the low-sulfur, low-vanadium petroleum coke is calcined at 1200°C.

[0020] Further, in S3, the process of batching according to particle size functionalization specifically involves: sieving the calcined petroleum coke into different particle sizes of 6–3 mm, 3–1 mm, 1–0.075 mm, and less than 0.075 mm. Specifically, the 6–3 mm and 3–1 mm particle sizes use the high-sulfur, low-vanadium petroleum coke; the 1–0.075 mm particle sizes use the low-sulfur, low-vanadium petroleum coke; and the fine powder particle size less than 0.075 mm uses both the high-sulfur, high-vanadium petroleum coke and the low-sulfur, low-vanadium petroleum coke, with the high-sulfur, high-vanadium petroleum coke as the primary component.

[0021] Furthermore, the particle size distribution adopts the conventional gradation method of aluminum electrolytic prebaked carbon anodes. The proportion of different particle sizes is adjusted according to the production conditions and determined under the premise that the sulfur content of the finished carbon anode is less than 2.3 wt% and the vanadium content is less than 350 ppm.

[0022] Furthermore, petroleum coke not used in the functionalized particle size distribution of this invention can be used to prepare carbon anodes of other specifications according to production needs, and its usage does not affect the technical effect of this invention.

[0023] Furthermore, in S4, the amount of coal tar pitch added is 16-20% of the total mass of calcined coke, the kneading temperature is 160-180℃, and the green anode is prepared by vibration molding.

[0024] Preferably, the amount of coal tar pitch added is 18% of the total mass of the calcined coke.

[0025] Preferably, the kneading temperature is 170°C.

[0026] Furthermore, the calcination described in S5 is carried out under air-isolated conditions, and the final calcination temperature is 1050–1150°C.

[0027] Preferably, the calcination temperature is 1100°C.

[0028] The reaction principle of this invention:

[0029] This invention addresses the problem that uniform calcination at a single temperature after blending makes it difficult to consider the calcination characteristics of different petroleum cokes and easily leads to structural shrinkage mismatch. Based on the differences in sulfur and vanadium content in the petroleum coke, it achieves synergistic control through differentiated calcination and particle-level functionalized ingredient formulation. High-sulfur, low-vanadium petroleum coke is calcined at high temperature to construct a stable and conductive anode framework. High-sulfur, high-vanadium petroleum coke is calcined at medium temperature and introduced in fine powder form, co-processing with the carbonization shrinkage of coal tar pitch during roasting. This improves the density and structural stability of the carbon anode while reducing resistivity and air reactivity.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. This invention avoids the problems of high-vanadium petroleum oxide active sites being exposed at high temperatures and high-sulfur petroleum coke being insufficiently calcined under uniform calcination conditions after blending by implementing differentiated calcination of petroleum coke with different sulfur and vanadium contents.

[0032] 2. This invention utilizes particle-level functionalization to enable high-sulfur, low-vanadium petroleum coke to act as a support structure. The high-sulfur, high-vanadium petroleum coke, in the form of fine powder, is densified in synergistic way with coal tar pitch during roasting. Under the premise of meeting the requirements of sulfur and vanadium indicators, the invention achieves comprehensive optimization of the densification, structural stability, resistivity and air reactivity of carbon anodes, so that the physical and chemical properties of the finished anode reach the level of traditional high-quality anodes.

[0033] 3. This invention does not require chemical devanadium removal from petroleum coke or the introduction of additional additives. The process flow is highly compatible with existing prebaked carbon anode production processes, which is conducive to improving the resource utilization level of high-sulfur and high-vanadium petroleum coke and has good industrial application value. Detailed Implementation

[0034] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following detailed description is provided in conjunction with specific embodiments.

[0035] The specifications of the petroleum coke raw material and binder used in the method of this invention are as follows:

[0036] Raw material A: high-sulfur, high-vanadium petroleum coke: sulfur content 4.65wt%, vanadium content 1130ppm.

[0037] Raw material B, high-sulfur, low-vanadium petroleum coke: sulfur content 4.52 wt%, vanadium content 165 ppm.

[0038] Raw material C: low-sulfur, low-vanadium petroleum coke: sulfur content 0.65wt%, vanadium content 46ppm.

[0039] Binder: Modified coal tar pitch, softening point 113℃, coking value 63%.

[0040] Example 1

[0041] A method for preparing carbon anodes using low-quality petroleum coke, comprising the following steps:

[0042] S1. Select raw material A as high-sulfur and high-vanadium petroleum coke, raw material B as high-sulfur and low-vanadium petroleum coke, and raw material C as low-sulfur and low-vanadium petroleum coke.

[0043] S2. Differential calcination treatments were carried out on three types of petroleum coke, with raw material A calcined at 1000℃, raw material B calcined at 1300℃, and raw material C calcined at 1200℃. The physicochemical properties of the three types of calcined coke after differential calcination are shown in Table 1.

[0044] S3. Based on a total mass of 4 kg of calcined coke, the following proportions are made: 6-3 mm particle size accounts for 27% of the total mass of calcined coke, 3-1 mm particle size accounts for 23%, and both particle sizes are made from calcined raw material B; 1-0.075 mm particle size accounts for 21%, and is made from calcined raw material C; powder particle size smaller than 0.075 mm accounts for 29%, of which calcined raw material A accounts for 66% of the total mass of powder and calcined raw material C accounts for 34%. The weighted average of the mass fractions of each type of calcined coke is used to calculate the theoretical sulfur content of the blended calcined coke system to be approximately 2.22 wt% and the theoretical vanadium content to be approximately 349 ppm.

[0045] S4. Subsequently, the calcined coke obtained above is added to 18% of the total mass of calcined coke in coal tar pitch and kneaded at 170°C. After kneading, the green anode is prepared by vibration molding.

[0046] S5. The green anode was calcined at 1100℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.598 g / cm³, resistivity was 52.05 μΩ·m, and air reactive residual rate was 90.5%.

[0047] Example 2

[0048] A method for preparing carbon anodes using low-quality petroleum coke, comprising the following steps:

[0049] S1. Select raw material A as high-sulfur and high-vanadium petroleum coke, raw material B as high-sulfur and low-vanadium petroleum coke, and raw material C as low-sulfur and low-vanadium petroleum coke.

[0050] S2. Differential calcination treatments were carried out on three types of petroleum coke, with raw material A calcined at 1000℃, raw material B calcined at 1300℃, and raw material C calcined at 1200℃. The physicochemical properties of the three types of calcined coke after differential calcination are shown in Table 1.

[0051] S3. Based on a total mass of 4 kg of calcined coke, the following proportions are made: 25% of the total mass of calcined coke is 6-3 mm, and 20% is 3-1 mm, both of which are made from calcined raw material B; 20% is 1-0.075 mm, made from calcined raw material C; and 35% is powder, of which 56% is calcined raw material A and 44% is calcined raw material C. The weighted average of the mass fractions of each type of calcined coke is used to calculate the theoretical sulfur content of the blended calcined coke system to be approximately 2.15 wt% and the theoretical vanadium content to be approximately 347 ppm.

[0052] S4. Subsequently, the calcined coke obtained above is added to 18% of the total mass of calcined coke in coal tar pitch and kneaded at 170°C. After kneading, the green anode is prepared by vibration molding.

[0053] S5. The green anode was calcined at 1100℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.587 g / cm³, resistivity was 53.25 μΩ·m, and air reactivity residual rate was 89.2%.

[0054] Example 3

[0055] A method for preparing carbon anodes using low-quality petroleum coke, comprising the following steps:

[0056] S1. Select raw material A as high-sulfur and high-vanadium petroleum coke, raw material B as high-sulfur and low-vanadium petroleum coke, and raw material C as low-sulfur and low-vanadium petroleum coke.

[0057] S2. Differential calcination treatments were carried out on three types of petroleum coke, with raw material A calcined at 1000℃, raw material B calcined at 1300℃, and raw material C calcined at 1200℃. The physicochemical properties of the three types of calcined coke after differential calcination are shown in Table 1.

[0058] S3. Based on a total mass of 4 kg of calcined coke, the following proportions are made: 30% of the total mass of calcined coke is 6-3 mm, 25% is 3-1 mm, and both of these proportions are made from calcined raw material B; 15% is 1-0.075 mm, made from calcined raw material C; and 30% is powder, of which 53% is calcined raw material A and 47% is calcined raw material C. The weighted average of the mass fractions of each type of calcined coke is used to calculate the theoretical sulfur content of the blended calcined coke system to be approximately 2.18 wt% and the theoretical vanadium content to be approximately 319 ppm.

[0059] S4. Subsequently, the calcined coke obtained above is added to 18% of the total mass of calcined coke in coal tar pitch and kneaded at 170°C. After kneading, the green anode is prepared by vibration molding.

[0060] S5. The green anode was calcined at 1100℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.599 g / cm³, resistivity was 51.67 μΩ·m, and air reactivity residual rate was 91.3%.

[0061] Example 4

[0062] A method for preparing carbon anodes using low-quality petroleum coke, comprising the following steps:

[0063] S1. Select raw material A as high-sulfur and high-vanadium petroleum coke, raw material B as high-sulfur and low-vanadium petroleum coke, and raw material C as low-sulfur and low-vanadium petroleum coke.

[0064] S2. Differential calcination treatments were carried out on three types of petroleum coke, with raw material A calcined at 950℃, raw material B calcined at 1250℃, and raw material C calcined at 1150℃. The physicochemical properties of the three types of calcined coke after differential calcination are shown in Table 1.

[0065] S3. Based on a total mass of 4 kg of calcined coke, the following proportions are made: 6-3 mm particle size accounts for 27% of the total mass of calcined coke, 3-1 mm particle size accounts for 23%, and both particle sizes are made from calcined raw material B; 1-0.075 mm particle size accounts for 21%, and is made from calcined raw material C; powder particle size smaller than 0.075 mm accounts for 29%, of which calcined raw material A accounts for 66% of the total mass of powder and calcined raw material C accounts for 34%. The weighted average of the mass fractions of each type of calcined coke is used to calculate the theoretical sulfur content of the blended calcined coke system to be approximately 2.27 wt% and the theoretical vanadium content to be approximately 349 ppm.

[0066] S4. Subsequently, the calcined coke obtained above is added to 16% of the total mass of calcined coke in coal tar pitch and kneaded at 160°C. After kneading, the green anode is prepared by vibration molding.

[0067] S5. The green anode was calcined at 1050℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.581 g / cm³, resistivity was 54.62 μΩ·m, and air reactive residual rate was 88.5%.

[0068] Example 5

[0069] A method for preparing carbon anodes using low-quality petroleum coke, comprising the following steps:

[0070] S1. Select raw material A as high-sulfur and high-vanadium petroleum coke, raw material B as high-sulfur and low-vanadium petroleum coke, and raw material C as low-sulfur and low-vanadium petroleum coke.

[0071] S2. Differential calcination treatments were carried out on three types of petroleum coke, with raw material A calcined at 1050℃, raw material B calcined at 1350℃, and raw material C calcined at 1250℃. The physicochemical properties of the three types of calcined coke after differential calcination are shown in Table 1.

[0072] S3. Based on a total mass of 4 kg of calcined coke, the following proportions are made: 6-3 mm particle size accounts for 27% of the total mass of calcined coke, 3-1 mm particle size accounts for 23%, and both particle sizes are made from calcined raw material B; 1-0.075 mm particle size accounts for 21%, and is made from calcined raw material C; powder particle size smaller than 0.075 mm accounts for 29%, of which calcined raw material A accounts for 66% of the total mass of powder and calcined raw material C accounts for 34%. The weighted average of the mass fractions of each type of calcined coke is used to calculate the theoretical sulfur content of the blended calcined coke system to be approximately 2.10 wt% and the theoretical vanadium content to be approximately 346 ppm.

[0073] S4. Subsequently, the calcined coke obtained above is added to 20% of the total mass of calcined coke in coal tar pitch and kneaded at 180°C. After kneading, the green anode is prepared by vibration molding.

[0074] S5. The green anode was calcined at 1150℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.587 g / cm³, resistivity was 53.85 μΩ·m, and air reactivity residual rate was 87.6%.

[0075] Comparative Example 1

[0076] S1. Select the above three types of petroleum coke as raw materials, wherein raw material A is high-sulfur and high-vanadium petroleum coke, raw material B is high-sulfur and low-vanadium petroleum coke, and raw material C is low-sulfur and low-vanadium petroleum coke.

[0077] S2. The three raw materials were calcined at 1200℃. The physicochemical properties of the three calcined cokes after calcination are shown in Table 1.

[0078] S3. Using a total mass of 4 kg of calcined coke as a baseline, the batching was carried out. The particle size division ratio remained the same as in Example 1, but no functional distinction was made in each particle size. Instead, the three raw materials were blended in each particle size according to the following ratio: 50% calcined raw material B, 19.14% calcined raw material A, and 30.86% calcined raw material C. The weighted average was calculated based on the mass fraction of each calcined coke. The theoretical sulfur content of the blended calcined coke system was approximately 2.64 wt%, which exceeded the requirement of less than 2.3 wt%. The theoretical vanadium content was approximately 346 ppm.

[0079] S4. Subsequently, the calcined coke obtained above is added to 18% of the total mass of calcined coke in coal tar pitch and kneaded at 170°C. After kneading, the green anode is prepared by vibration molding.

[0080] S5. The green anode was calcined at 1100℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.561 g / cm³, resistivity was 61.32 μΩ·m, and air reactivity residual rate was 82.2%.

[0081] Comparative Example 2

[0082] S1. Select the above three types of petroleum coke as raw materials, wherein raw material A is high-sulfur and high-vanadium petroleum coke, raw material B is high-sulfur and low-vanadium petroleum coke, and raw material C is low-sulfur and low-vanadium petroleum coke.

[0083] S2. Differential calcination treatments were carried out on three types of petroleum coke, with raw material A calcined at 1000℃, raw material B calcined at 1300℃, and raw material C calcined at 1200℃. The physicochemical properties of the three types of calcined coke after differential calcination are shown in Table 1.

[0084] S3. Using a total mass of 4 kg of calcined coke as a baseline, the batching was carried out. The particle size division ratio remained the same as in Example 1, but no functional distinction was made in each particle size. Instead, the three raw materials were blended in each particle size according to the following ratio: 50% calcined raw material B, 19.14% calcined raw material A, and 30.86% calcined raw material C. The weighted average was calculated based on the mass fraction of each calcined coke, and the theoretical sulfur content of the blended calcined coke system was approximately 2.22 wt%, and the theoretical vanadium content was approximately 349 ppm.

[0085] S4. Subsequently, the calcined coke obtained above is added to 18% of the total mass of calcined coke in coal tar pitch and kneaded at 170°C. After kneading, the green anode is prepared by vibration molding.

[0086] S5. The green anode was calcined at 1100℃, and the performance of the calcined carbon anode was tested. Its bulk density was 1.568 g / cm³, resistivity was 57.52 μΩ·m, and air reactivity residual rate was 86.2%.

[0087] Results Analysis: Table 2 shows that the carbon anodes prepared using the process of this invention (Examples 1 to 5) have a bulk density of 1.581~1.599 g / cm³, a resistivity of 51.67~54.62 μΩ·m, and an air reactive residue rate of 87.6%~91.3%. All of these key physicochemical indicators are superior to the industry standard TY-1. Compared with Comparative Example 1, the air reactive residue rate of each example is significantly improved, and the resistivity is significantly reduced, indicating that the differentiated calcination process is beneficial to improving the internal structural stability of the anode and enhancing its oxidation resistance. Compared with Comparative Example 2, each example shows better performance in both bulk density and resistivity, indicating that by rationally allocating the functional particle size distribution of the calcined coke, the density of the carbon anode can be improved and the resistivity reduced. These results demonstrate that this invention, through the synergistic effect of differentiated calcination and functionalized particle size distribution, ensures the quality of the finished carbon anode while incorporating inferior coke.

[0088] Table 1. Physicochemical properties of three types of calcined coke under different calcination conditions.

[0089]

[0090] Table 2 Performance of the anodes in the examples, comparative examples, and carbon anodes according to the YS / T285—2022 industry standard

[0091]

[0092] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing carbon anodes using low-quality petroleum coke, characterized in that, The steps include the following: S1. Based on the differences in sulfur and vanadium content in petroleum coke, the raw materials are divided into three categories: high-sulfur and high-vanadium petroleum coke, high-sulfur and low-vanadium petroleum coke, and low-sulfur and low-vanadium petroleum coke. S2. Differentiately calcine the above three types of petroleum coke; S3. The calcined petroleum coke is crushed and screened, and then batched according to particle size functionalization. S4. Mix the above ingredients with coal tar pitch, knead and shape to make a raw anode; S5. The green anode is roasted.

2. The method as described in claim 1, characterized in that, In S1, the high-sulfur, high-vanadium petroleum coke is petroleum coke with a sulfur content >4wt% and a vanadium content >400ppm; the high-sulfur, low-vanadium petroleum coke is petroleum coke with a sulfur content >4wt% and a vanadium content <200ppm; and the low-sulfur, low-vanadium petroleum coke is petroleum coke with a sulfur content <2wt% and a vanadium content <200ppm.

3. The method as described in claim 1, characterized in that, In S2, the differentiated calcination specifically refers to: the high-sulfur, high-vanadium petroleum coke being calcined at 950–1050°C; the high-sulfur, low-vanadium petroleum coke being calcined at 1250–1350°C; and the low-sulfur, low-vanadium petroleum coke being calcined at 1150–1250°C.

4. The method as described in claim 1, characterized in that, In S3, the specific method of batching according to particle size functionalization is as follows: the calcined petroleum coke is sieved into different particle sizes of 6-3mm, 3-1mm, 1-0.075mm, and less than 0.075mm. Among them, the 6-3mm and 3-1mm particle sizes use the high-sulfur, low-vanadium petroleum coke; the 1-0.075mm particle sizes use the low-sulfur, low-vanadium petroleum coke; and the fine powder particle sizes less than 0.075mm use both the high-sulfur, high-vanadium petroleum coke and the low-sulfur, low-vanadium petroleum coke, with the high-sulfur, high-vanadium petroleum coke as the main component.

5. The method as described in claim 4, characterized in that, The particle size distribution adopts the conventional gradation method of aluminum electrolytic prebaked carbon anodes. The proportion of different particle sizes is adjusted according to the production conditions and is determined under the premise that the sulfur content of the finished carbon anode is less than 2.3wt% and the vanadium content is less than 350ppm.

6. The method as described in claim 1, characterized in that, In S4, the amount of asphalt added is 16-20% of the total mass of the ingredients, the mixing temperature is 160-180℃, and the green anode is prepared by vibration molding.

7. The method as described in claim 1, characterized in that, In S5, the calcination conditions are as follows: the calcination is carried out under air-isolated conditions, and the final calcination temperature is 1050-1150℃.

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