A treatment method for comprehensive utilization of carbon tailings

Abstract

The present invention discloses a treatment method for comprehensive utilization of carbon tailings. Through the comprehensive reuse of carbon tailings, a large amount of carbon tailings such as high-ash dust collecting powder of returned materials, overhead crane dust collecting powder, and melted asphalt are consumed, saving environmental protection cost investment, effectively alleviating environmental protection pressure, and reducing environmental protection risks; at the same time, it also saves raw material procurement costs. The anode baking process is optimized to reduce the quality risk of binder segregation, ensure that the temperature rise curve is more adaptable to the anode baking process of tailings reuse, and solve the technical problems of carbon tailings reuse that have long plagued pre-baked anode production enterprises; the physical and chemical indicators of the produced pre-baked anode blocks remain stable, and the highest qualified rate reaches 98.86%. At the same time, melted asphalt and returned dust collecting powder are used to produce carbon bowl filling materials, which are used as winter antifreeze and heat preservation fuels, saving fuel procurement costs. This method is safe and reliable, with mature technology, and can be promoted and applied in the carbon industry.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of carbon tailings, and in particular to a processing method for comprehensive utilization of carbon tailings. Background Art

[0002] As the main raw material for anode production, carbon material is consumed continuously during the production of aluminum electrolysis along with the generation of metallic aluminum. Therefore, the demand for carbon material is very high.

[0003] The main task of the raw anode production system in the carbon plant molding workshop is to provide qualified raw anodes required for production for roasting and to do a good job in equipment operation and maintenance. The molding workshop consists of the high-rise section, vibration molding section, asphalt melting section and return material processing section. Among them, the high-rise section crushes, screens and mixes the materials from the 100 series, 200 series and 300 series with the melted qualified asphalt, preheats, kneads and cools them to obtain qualified paste, which is then transported to the vibration molding section to produce qualified green blocks. The asphalt melting section provides heat source (heating medium is heat transfer oil) and qualified liquid asphalt for the preparation of anode paste for the high-rise section. The return material processing section crushes the residual anode returned by electrolysis and the waste paste and waste green blocks generated by the roasting and molding processes and re-uses them in the production process. The ash content of this part of the dust collection powder is high (10-14%), which does not meet the requirements for production line reuse. On average, 35 to 40 tons of dust powder is generated each month, and about 465 tons is generated throughout the year. It is collected by the dust removal system and stored in compliance with regulations. The disposal method is unified outsourcing for transportation and treatment, which invisibly increases costs.

[0004] During the roasting process, the multifunctional overhead crane dust removal system and the carbon block disassembly process will produce overhead crane dust powder. Due to its small particle size, it is difficult to reuse it directly. It is collected and stored by the dust removal system. About 710 tons are generated throughout the year. After being collected by the dust removal system, they are stored in compliance with regulations. After sampling, testing and analysis, the ash content of the overhead crane dust powder is 3-7%, which is lower than that of the return material dust powder and can be reused in the production line. During the roasting process, a large amount of molten asphalt generated by the flue gas purification system is collected by the purification electric dust collector and discharged into oil drums for compliance storage. About 536 tons of molten asphalt are generated throughout the year. There is also filler fine powder whose particle size becomes smaller due to mechanical wear and other factors after long-term use. It is collected after being filtered through a screen.

[0005] In summary, the four types of carbon tailings, including dust collected by return materials, dust collected by overhead cranes, melted asphalt and fine filler powder, occupy the site, affect the standardized management of the site; the storage site is limited, which poses a great environmental risk; outsourcing disposal requires a large investment in environmental protection costs; the recycling rate is low, resulting in waste of resources, etc. Therefore, it is urgent to design a treatment plan for the comprehensive utilization of carbon tailings. Summary of the invention

[0006] Based on the above technical problems, the purpose of the present invention is to provide a processing method for comprehensive utilization of carbon tailings.

[0007] The present invention protects a method for comprehensive utilization of carbon tailings, wherein the tailings processed by the method include return material dust collection powder, overhead crane dust collection powder, melted asphalt and filler fine powder;

[0008] The filler fine powder, overhead crane dust collecting powder and melted asphalt are used to produce prebaked anodes, and the specific steps include the following:

[0009] Step 1, kneading the tailings: First, 60-80% of filler powder by mass is put into the kneading pot through the roasting multifunctional crane, and 10-20% of the dust collected by the crane by mass is transported to the kneading pot by the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, 10-20% of the melted asphalt by mass is heated by the roasting process flue gas heating barrel removal device, and the melted asphalt is transported to the kneading pot through the asphalt pump; finally, at 80-120°C, after kneading for 15-25 minutes, the kneaded tailings are turned out of the pot;

[0010] Step 2, pre-baked anode production paste matching: after the kneading tailings of step 1 are conveyed to the return material section of the molding process, they are matched with unqualified pre-baked anode scraps in a ratio of 1:1 to form raw scraps, and then mixed with other materials in a kneader in a certain proportion to form dry materials, and then a certain proportion of molten asphalt is added to mix into a paste, and then enters the pre-baked anode production system; wherein the pre-baked anode production paste ratio is composed of the following materials by mass percentage: coarse coke 11.0-11.8%, medium coke 10.8-11.4%, coarse residue 9.8-11.0%, raw scrap 3.5-10.0%, fine coke 17.6-22.6%, powder coke 31.7-33.3%, fine residue 8.8-9.8%, molten asphalt 3.5-4.2t / h;

[0011] Step 3, prebaked anode production: the speed of the above-mentioned kneading machine is controlled at 48-54 rpm, the dry material temperature is controlled at 158-163° C., the paste temperature is controlled at 180-182° C., the integrated power is controlled at 220-240 kW, the integrated torque is controlled at 72-74%, the maximum torque is 65-74%, and then kneading is performed, and the kneaded paste is poured into a prebaked anode mold for baking;

[0012] Step 4, prebaked anode baking: the prebaked anode mold of step 3 is loaded into the baking furnace for baking, and the baking furnace is subjected to a 192h heating curve, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1 per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8 per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9 per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5 per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h; after cooling, the prebaked anode can be taken out;

[0013] Step 5, pre-baked anode block index testing: the apparent density, true density, compressive strength, CO2 reactivity (residual electrode rate), resistivity, thermal expansion coefficient and ash content of the produced pre-baked anode are tested.

[0014] Furthermore, in step 1, the injection amount of the molten asphalt is controlled by time, and the injection time of the molten asphalt in the unit kneading pot is 10 to 15 seconds.

[0015] Furthermore, in the step 1, the tailings are kneaded: first, 70% by mass of filler fine powder is put into the kneading pot through the roasting multifunctional overhead crane, and 18% by mass of overhead crane dust collection powder is transported to the kneading pot by the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, the roasting process flue gas is used to heat the barrel-removing device to heat 12% by mass of molten asphalt, and the molten asphalt is transported to the kneading pot by the asphalt pump; finally, at 100°C, the kneading tailings are turned out of the pot after kneading for 20 minutes.

[0016] Furthermore, in step 2, other materials include coarse coke with a particle size of 6 to 12 mm, medium coke with a particle size of 3 to 6 mm, coarse residue with a particle size of 3 to 12 mm, fine coke with a particle size of 0 to 3 mm, powder coke with a particle size ≤ 0.075 mm, and fine residue with a particle size of 0 to 3 mm.

[0017] Furthermore, in step 2, the prebaked anode production paste ratio consists of the following materials in mass percentage: 11.0% crude coke, 10.9% medium coke, 11.0% crude residue, 6.0% raw crushed material, 18.6% fine coke, 32.7% powder coke, 9.8% fine residue, and 3.7-4.0 t / h of molten asphalt.

[0018] Furthermore, the melted asphalt and the returned dust powder are used to produce charcoal bowl filler, and the specific steps include the following:

[0019] Step S1, kneading the tailings: first, use the ash conveying screw device to convey 70-90% of the return material dust powder by mass to the kneading pot; then, start the kneading device to dry mix for 10 minutes, and then use the roasting process flue gas to heat the barrel-removing device to heat 10-30% of the molten asphalt by mass, and convey the molten asphalt to the kneading pot through the asphalt pump; finally, at 80-120°C, knead for 15-25 minutes and then turn the kneaded tailings out of the pot;

[0020] Step S2, tailings filling: the tailings kneaded in step S1 are put into the anode carbon bowl for standby use;

[0021] Step S3, roasting of anode carbon bowl: the anode carbon bowl of step S2 is loaded into the roasting furnace for roasting, and the roasting furnace is subjected to a 192h heating curve, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1 per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8 per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9 per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5 per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h;

[0022] Step S4, roasting the anode carbon bowl: the roasted carbon bowl is taken out and used as winter antifreeze and heat preservation fuel after cooling.

[0023] Furthermore, in the step S1, first, the dust collection powder of the return material with a mass percentage of 82% is transported to the kneading pot by using the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, the molten asphalt with a mass percentage of 18% is heated by the barrel removal device using the smoke from the roasting process, and the molten asphalt is transported to the kneading pot by the asphalt pump; finally, at 100°C, after kneading for 20 minutes, the kneading tail material is turned out of the pot.

[0024] Compared with the existing technology, the present invention has the following beneficial effects:

[0025] The method of the present invention consumes a large amount of carbon tailings such as high-ash dust collecting powder, overhead crane dust collecting powder, and melted asphalt through comprehensive recycling of carbon tailings, saving a large amount of environmental protection cost investment, effectively alleviating environmental pressure, and reducing environmental risks; it also saves raw material procurement costs. The anode baking process is optimized to reduce the quality risk of binder segregation, ensure that the heating curve is more suitable for the anode baking process of tailings recycling, and solve the technical problems that have long plagued prebaked anode production enterprises in the recycling of carbon tailings; the prebaked anode blocks produced have an ash content of ≤0.8%, a resistivity of ≤62μΩ·m, a compressive strength of ≥32MPa, and a carbon dioxide reactivity of ≥73.0%. The physical and chemical indicators remain stable, and the qualified rate is as high as 98.86%; the raw anode produced has an ash content of ≤0.8%, a volatile content of 6.5-9.0%, a compressive strength of ≥32Mpa, and a true density of ≥1.60g / cm 3 , the physical and chemical indicators remain stable, and the qualified rate reaches more than 98%. At the same time, the melted asphalt and the dust powder of the return material are used to produce the filling material of the carbon bowl, which is used as the antifreeze and heat preservation fuel in winter, saving the fuel purchase cost. The production practice has proved that the application method is safe and reliable, the technology is mature, and it can be promoted and applied in the carbon industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is a process flow chart of the method of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1

[0029] 1. Filler powder, overhead crane dust collection powder and melted asphalt are used to produce prebaked anodes

[0030] (1) Mixing of tailings

[0031] Firstly, 60-80% of filler fine powder by weight is put into a kneading pot through a roasting multifunctional overhead crane, and 10-20% of the dust collected by the overhead crane by weight is transported to the kneading pot by an ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, 10-20% of the molten asphalt by weight is heated by a roasting process flue gas heating barrel removal device, and the molten asphalt is transported to the kneading pot through an asphalt pump, wherein the injection amount of the molten asphalt is controlled by time, and the injection time of the molten asphalt in a unit kneading pot is 10-15 seconds; finally, at 80-120°C, the kneading tail material is turned out of the pot after kneading for 15-25 minutes.

[0032] (2) Prebaked anode production paste matching

[0033] After the kneading tailings are transported to the return material section of the molding process, they are mixed with unqualified pre-baked anode crushed materials in a 1:1 ratio to form raw crushed materials, and then mixed with other materials in a certain proportion in a kneader to form dry materials. After adding a certain proportion of molten asphalt to mix into a paste, they enter the pre-baked anode production system; among them, other materials include coarse coke with a particle size of 6-12mm, medium coke with a particle size of 3-6mm, coarse residue with a particle size of 3-12mm, fine coke with a particle size of 0-3mm, powder coke with a particle size ≤0.075mm and fine residue with a particle size of 0-3mm.

[0034] 1) Optimization process of paste ratio for prebaked anode production

[0035] Table 1 Optimization of paste ratio for prebaked anode production

[0036] Raw material name Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Coarse focus (6-12mm) 11.0 11.8 11.0 11.0 11.0 Middle focus (3-6mm) 11.4 10.8 10.9 10.9 10.9 Rough residue (3~12mm) 11.0 9.8 11.0 11.0 11.0 Raw material (0~3mm) 3.5 3.5 6.0 8.0 10 Fine focus (0~3mm) 20.0 22.6 18.6 17.6 17.6 Powder coke (≦0.075mm) 33.3 32.7 32.7 32.7 31.7 Fine residue (0~3mm) 9.8 8.8 9.8 8.8 8.8 Melting Asphalt 3.5-4.2t / h 3.7-4.0t / h 3.7-4.0t / h 3.7-4.0t / h 3.7-4.0t / h

[0037] 2) Analysis of anode test blocks before prebaked anode firing

[0038] After analyzing the anode test blocks (raw anode test blocks) produced from the above raw materials before baking, it was found that the melted asphalt mixed with the filler fine powder in the kneading tailings can effectively infiltrate and penetrate into the honeycomb-shaped voids of the calcined coke, and effectively bite and fill the gaps between the particles, which can improve the quality of the anode. After the formula is optimized, the technicians are organized to analyze and judge the raw anode test blocks with different ratios of raw crushed materials after the raw anode test blocks are produced.

[0039] 3) Determine the ratio of raw and crushed materials

[0040] According to the proportion of the four raw and scrap materials on the line, test blocks are produced according to different proportions, the physical and chemical indicators are tracked and compared, and the reasonable proportion of tailings added is determined based on the physical and chemical indicators (see Table 2 for details).

[0041] Table 2 Indicators of raw anode test blocks under different raw crushing ratios

[0042]

[0043] When the added raw scrap accounts for more than 6%, the ash content of the raw anode test block exceeds the standard requirement. When the raw scrap accounts for less than 6%, all indicators of the raw anode test block meet the technical standard requirements. Therefore, based on the test results, it is finally determined that batch trial production can be carried out when the proportion of kneading tailings is 6% or less.

[0044] 4) Analysis of test block indicators during the pilot phase of raw anode test blocks

[0045] After determining the material formula of the raw anode test blocks, a mid-term test was carried out to produce 144 test blocks with raw crushed materials. The physical and chemical indicators of the anode test blocks before roasting were statistically analyzed compared with those of the control anode test blocks without raw crushed materials. See Tables 3 and 4 for details.

[0046] Table 3 Indicators of raw anode test blocks produced by pilot production with raw crushed materials

[0047]

[0048] Table 4 Indicators of raw anode test blocks produced in pilot production without adding raw crushed materials

[0049]

[0050] As can be seen from Tables 3 and 4, the appearance quality and physical and chemical indicators of the raw anode test blocks produced after adding raw scraps are relatively stable, the qualified rate reaches more than 98%, and the physical and chemical indicators and appearance quality are significantly improved.

[0051] In summary, the final ratio of prebaked anode production paste is determined to be composed of the following materials in mass percentage: coarse coke 11.0%, medium coke 10.9%, coarse residue 11.0%, raw crushed material 6.0%, fine coke 18.6%, powder coke 32.7%, fine residue 9.8%, and molten asphalt 3.7-4.0 t / h.

[0052] (3) Prebaked anode production

[0053] 1) Optimization of prebaked anode production process parameters

[0054] In order to ensure the quality of prebaked anodes, tailings are used to produce prebaked anodes, and the kneading machine and production process parameters are optimized (see Table 5 for details).

[0055] Table 5 Optimization of prebaked anode production process parameters

[0056]

[0057]

[0058] For continuous kneading, the kneading power and torque can be increased by reducing the speed. When it is reduced to a certain range, the accumulation of paste in the cavity is conducive to turning and kneading, but if the duration is too long, it is easy to cause blockage and poor uniform kneading effect. If it is too short, the kneading effect is not good, which will affect the quality of the raw block. The kneading power directly affects the quality of the paste. If the kneading power is too high, it is easy to cause the large particles in the formula to be crushed, so that the particle size balance is destroyed, and at the same time, the paste is accumulated too much in the kneading machine, causing blockage. If it is too low, the kneading effect is not good, the asphalt fails to penetrate into the pores well, and the product quality is significantly reduced. According to the test results, when the dry material temperature and the molten asphalt temperature fluctuate, the paste temperature is controlled between 180 and 182 ° C, and the dry material temperature is controlled between 158 and 163 ° C. The best integrated power is 220-240kW, the integrated torque is 72-74%, the kneading machine runs smoothly, and various parameters can be accurately controlled.

[0059] In summary, the speed of the kneading machine is controlled at 48-54 rpm, the dry material temperature is controlled at 158-163° C., the paste temperature is controlled at 180-182° C., the integrated power is controlled at 220-240 kW, the integrated torque is controlled at 72-74%, and the maximum torque is 65-74%. Then, kneading is performed, and the kneaded paste is poured into a prebaked anode mold for baking.

[0060] (4) Prebaked anode calcination

[0061] During the anode roasting process, as the temperature rise curve in the roasting furnace changes, a series of physical and chemical changes occur inside the anode product, and it is these changes that affect the final porosity, resistivity, mechanical strength and oxidation characteristics of the anode product during electrolysis, and determine the final quality of the anode product. In order to ensure the quality of anode roasting after the comprehensive utilization of tailings, the 192h temperature rise curve implemented by the roasting furnace is optimized to ensure that the temperature rise curve is more suitable for the anode roasting process of tailings reuse. In order to increase the heating rate at this stage, the heating rates of 2P and 3P are appropriately increased to reduce the quality risk of binder segregation. The optimized anode roasting process is shown in Table 6.

[0062] Table 6 192h heating curve of roasting furnace

[0063]

[0064] Finally, the prebaked anode mold is placed in a baking furnace for baking, and is taken out after cooling to obtain a prebaked anode.

[0065] (5) Prebaked anode index detection

[0066] The apparent density, true density, compressive strength, CO2 reactivity (residual electrode rate), resistivity, thermal expansion coefficient and ash content of the prebaked anode produced by adding raw scrap were tested (see Table 7 for details).

[0067] Table 7 Physical and chemical indicators of prebaked anodes with added raw crushed materials

[0068]

[0069]

[0070] In order to better understand the physical and chemical indicators of the test blocks, the physical and chemical indicators of the prebaked anodes produced without adding raw scraps were compared. The statistics of the physical and chemical indicators of the prebaked anodes produced without adding raw scraps are shown in Table 8.

[0071] Table 8 Physical and chemical indicators of prebaked anode without adding raw crushed materials

[0072]

[0073]

[0074] As can be seen from Tables 7 and 8, the physical and chemical indicators of several batches of prebaked anodes were randomly selected for analysis. The prebaked anodes produced with raw scraps had a compressive strength that was 2.92MPa higher and a resistivity that was 0.58μΩ·m lower than those produced without adding raw scraps. There was no significant change in other physical and chemical indicators, and the anode qualification rate was increased from 98.25% to 98.865%.

[0075] From the analysis of the pre-baked anode after roasting, after the 192h heating curve of the roasting furnace was optimized, the resistivity test results were relatively good, the temperature difference of each fire channel was reduced from 102℃ to 84℃, and the setting value of the 192h roasting curve was in line with the actual production of tailings utilization blocks.

[0076] The trial application of prebaked anodes with added raw scrap on aluminum electrolytic cells was carried out to avoid affecting aluminum electrolysis production, and timely tracked and analyzed the changes in the production process and technical indicators of the aluminum electrolytic cells. After three months of tracking and analysis, it was found that the prebaked anodes with added raw scrap had no negative impact on the technical parameters of aluminum electrolysis production process, the anode service life, and technical and economic indicators, and were used normally.

[0077] 2. Melted asphalt and returned dust powder are used to produce carbon bowl filling material

[0078] (1) Mixing of tailings

[0079] First, the dust collecting powder of the return material with a mass percentage of 70-90% is transported to the kneading pot by using the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, the molten asphalt with a mass percentage of 10-30% is heated by the roasting process flue gas heating barrel removal device, and the molten asphalt is transported to the kneading pot by the asphalt pump; finally, the kneading tail material is turned out of the pot after kneading at 80-120°C for 15-25 minutes;

[0080] (2) Tailing filling

[0081] Put the kneaded tailings into the anode carbon bowl for later use;

[0082] (3) Anode carbon bowl roasting

[0083] The anode carbon bowl is loaded into the roasting furnace for roasting, and a 192h heating curve is applied to the roasting furnace, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1 per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8 per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9 per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5 per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h;

[0084] (4) Anode carbon bowl roasting

[0085] The charcoal bowl is taken out after roasting and used as winter antifreeze and heat preservation fuel after cooling. It has been used in production posts with good results and saved fuel purchase costs.

[0086] Example 2

[0087] Filler fine powder, overhead crane dust collection powder and melted asphalt are used to produce prebaked anodes. The specific steps include the following:

[0088] Step 1, kneading of tailings: First, 70% of filler powder by mass is put into the kneading pot through the roasting multifunctional crane, and 18% of the dust collected by the crane by mass is transported to the kneading pot by the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, 12% of the molten asphalt by mass is heated by the roasting process flue gas heating barrel removal device, and the molten asphalt is transported to the kneading pot through the asphalt pump; wherein, the injection amount of the molten asphalt is controlled by time, and the injection time of the molten asphalt in the unit kneading pot is 10 to 15 seconds; finally, at 100°C, after kneading for 20 minutes, the kneading tailings are turned out of the pot;

[0089] Step 2, pre-baked anode production paste matching: after the kneading tailings of step 1 are conveyed to the return material section of the molding process, they are matched with unqualified pre-baked anode scraps in a ratio of 1:1 to form raw scraps, and then mixed with other materials in a kneading machine in a certain proportion to form dry materials, and then a certain proportion of molten asphalt is added to mix into a paste, and then enter the pre-baked anode production system; wherein the other materials include coarse coke with a particle size of 6 to 12 mm, medium coke with a particle size of 3 to 6 mm, coke, coarse residue with a particle size of 3 to 12 mm, fine coke with a particle size of 0 to 3 mm, powder coke with a particle size of ≤0.075 mm, and fine residue with a particle size of 0 to 3 mm; finally, the prebaked anode production paste ratio is composed of the following raw materials by mass percentage: coarse coke 11.0%, medium coke 10.9%, coarse residue 11.0%, raw crushed material 6.0%, fine coke 18.6%, powder coke 32.7%, fine residue 9.8%, and molten asphalt 3.7 to 4.0 t / h;

[0090] Step 3, prebaked anode production: the speed of the above-mentioned kneading machine is controlled at 48-54 rpm, the dry material temperature is controlled at 158-163° C., the paste temperature is controlled at 180-182° C., the integrated power is controlled at 220-240 kW, the integrated torque is controlled at 72-74%, the maximum torque is 65-74%, and then kneading is performed, and the kneaded paste is poured into a prebaked anode mold for baking;

[0091] Step 4, prebaked anode baking: the prebaked anode mold of step 3 is loaded into the baking furnace for baking, and the baking furnace is subjected to a 192h heating curve, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1 per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8 per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9 per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5 per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h; after cooling, the prebaked anode can be taken out;

[0092] Step 5, pre-baked anode block index testing: the apparent density, true density, compressive strength, CO2 reactivity (residual electrode rate), resistivity, thermal expansion coefficient and ash content of the produced pre-baked anode are tested.

[0093] Example 3

[0094] The melted asphalt and the returned dust powder are used to produce the carbon bowl filler. The specific steps include the following:

[0095] Step S1, kneading of tailings: First, the dust collecting powder of the return material with a mass percentage of 82% is conveyed to the kneading pot by using the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, the molten asphalt with a mass percentage of 18% is heated by the roasting process flue gas heating barrel removal device, and the molten asphalt is conveyed to the kneading pot by the asphalt pump; finally, at 100°C, after kneading for 20 minutes, the kneading tailings are turned out of the pot;

[0096] Step S2, tailings filling: the tailings kneaded in step S1 are put into the anode carbon bowl for standby use;

[0097] Step S3, roasting of anode carbon bowl: the anode carbon bowl of step S2 is loaded into the roasting furnace for roasting, and the roasting furnace is subjected to a 192h heating curve, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1 per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8 per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9 per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5 per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h;

[0098] Step S4, roasting the anode carbon bowl: the roasted carbon bowl is taken out and used as winter antifreeze and heat preservation fuel after cooling.

[0099] Example 4

[0100] Estimation of economic benefits after comprehensive utilization of tailings

[0101] 1. After comprehensive utilization of carbon tailings, by the end of the year, a total of 533.78 tons of melted asphalt had been reused:

[0102] (1) Annual cumulative savings on melted asphalt disposal costs: 533.78 tons × 2,400 yuan / ton (melted asphalt disposal costs) = 1,281,072 yuan ≈ 1.28 million yuan.

[0103] (2) Savings on liquid asphalt purchase costs: By the end of the year, a total of 533.78 tons of melted asphalt had been reused, of which 485 tons entered the raw anode production system to replace liquid asphalt. The total savings on liquid asphalt purchase costs were: 485 tons × 4,600 yuan / ton (average purchase price of liquid asphalt from January to December, excluding tax) = 2,231,000 yuan ≈ 2.23 million yuan.

[0104] 2. After comprehensive utilization of carbon tailings, by the end of the year, a total of 779.5 tons of dust collected from returned materials and overhead cranes were recycled. The annual cumulative cost savings from the reuse of dust collected is: 779.5 tons × 3,480 yuan / ton (average purchase price of calcined coke from January to December, excluding tax) - 779.5 tons × 190 yuan / ton (export price of dust collected) = 2,564,555 yuan ≈ 2.56 million yuan.

[0105] 3. After comprehensive utilization of carbon tailings, by the end of the year, a total of about 101 tons of carbon bowl materials were produced, and the annual cumulative savings in fuel procurement costs were: 101 tons × 1,000 yuan / ton (average coal price) = 101,000 yuan ≈ 100,000 yuan.

[0106] 4. Generate costs

[0107] (1) By the end of the year, the tailings transfer vehicle consumed a total of 351 kg of diesel, with an annual cumulative fuel cost of: 0.351 tons × 7182 yuan / ton (current diesel price) = 2520 yuan ≈ 25,000 yuan.

[0108] (2) When the residual heat cannot be utilized during the operation of the furnace, electric heating is used to melt the asphalt and remove it from the barrel. By the end of the year, the tailings mixing process consumed a total of 224,000 kWh of power electricity. The annual cumulative power electricity cost is: 224,000 kWh × 0.3080 yuan / kWh (the average unit price of power electricity from January to December) = 68,990 yuan ≈ 69,000 yuan.

[0109] (3) Maintenance costs: The monthly regular maintenance of the tail material kneading device incurs maintenance costs of approximately RMB 1,000, and the annual costs are approximately RMB 12,000.

[0110] By the end of the year, through the comprehensive utilization of carbon tailings, direct economic benefits were generated: 1.28 million yuan (cost of melted asphalt disposal) + 2.23 million yuan (savings on liquid asphalt purchase costs) + 2.56 million yuan (cost savings from dust powder recycling) + 100,000 yuan (savings on fuel purchase costs) - 2,500 yuan (fuel consumption costs of transfer vehicles) - 69,000 yuan (power electricity consumption costs) - 12,000 yuan (equipment maintenance costs) = 6.0865 million yuan.

[0111] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for comprehensive utilization of carbon tailings, wherein the tailings processed by the method include return material dust collection powder, overhead crane dust collection powder, melted asphalt and filler fine powder; characterized in that: The filler fine powder, overhead crane dust collecting powder and melted asphalt are used to produce prebaked anodes, and the specific steps include the following: Step 1, kneading the tailings: First, 60-80% of filler powder by mass is put into the kneading pot through the roasting multifunctional crane, and 10-20% of the dust collected by the crane by mass is transported to the kneading pot by the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, 10-20% of the molten asphalt by mass is heated by the roasting process flue gas heating barrel removal device, and the molten asphalt is transported to the kneading pot through the asphalt pump; finally, at 80-120°C, after kneading for 15-25 minutes, the kneading tailings are turned out of the pot; the injection amount of the molten asphalt is controlled by time, and the injection time of the molten asphalt in the unit kneading pot is 10-15 seconds; Step 2, pre-baked anode production paste matching: after the kneading tailings of step 1 are conveyed to the return material section of the molding process, they are matched with unqualified pre-baked anode scraps in a ratio of 1:1 to form raw scraps, and then mixed with other materials in a kneader in a certain proportion to form dry materials, and then a certain proportion of molten asphalt is added to mix into a paste, and then enters the pre-baked anode production system; wherein the pre-baked anode production paste ratio is composed of the following materials by mass percentage: coarse coke 11.0-11.8%, medium coke 10.8-11.4%, coarse residue 9.8-11.0%, raw scrap 3.5-10.0%, fine coke 17.6-22.6%, powder coke 31.7-33.3%, fine residue 8.8-9.8%, molten asphalt 3.5-4.2t / h; Step 3, prebaked anode production: the speed of the above-mentioned kneading machine is controlled at 48-54 rpm, the dry material temperature is controlled at 158-163° C., the paste temperature is controlled at 180-182° C., the integrated power is controlled at 220-240 kW, the integrated torque is controlled at 72-74%, the maximum torque is 65-74%, and then kneading is performed, and the kneaded paste is poured into a prebaked anode mold for baking; Step 4, prebaked anode baking: the prebaked anode mold of step 3 is loaded into the baking furnace for baking, and the baking furnace is subjected to a 192h heating curve, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1°C per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8°C per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9°C per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5°C per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h; after cooling, the prebaked anode can be taken out; Step 5, pre-baked anode block index testing: the apparent density, true density, compressive strength, CO2 reactivity, resistivity, thermal expansion coefficient and ash content of the produced pre-baked anode are tested.

2. The method for comprehensive utilization of carbon tailings according to claim 1, characterized in that: In the step 1, the tailings are kneaded: first, 70% by mass of filler fine powder is put into the kneading pot by the roasting multifunctional overhead crane, and 18% by mass of overhead crane dust collection powder is transported to the kneading pot by the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, 12% by mass of molten asphalt is heated by the roasting process flue gas heating barrel removal device, and the molten asphalt is transported to the kneading pot by the asphalt pump; finally, at 100°C, after kneading for 20 minutes, the kneaded tailings are turned out of the pot.

3. The method for comprehensive utilization of carbon tailings according to claim 1, characterized in that: In step 2, other materials include coarse coke with a particle size of 6 to 12 mm, medium coke with a particle size of 3 to 6 mm, coarse residue with a particle size of 3 to 12 mm, fine coke with a particle size of 0 to 3 mm, powder coke with a particle size of ≦0.075 mm, and fine residue with a particle size of 0 to 3 mm.

4. The method for comprehensive utilization of carbon tailings according to claim 1, characterized in that: In step 2, the prebaked anode production paste ratio is composed of the following materials in mass percentage: 11.0% coke, 10.9% medium coke, 11.0% coarse residue, 6.0% raw crushed material, 18.6% fine coke, 32.7% powder coke, 9.8% fine residue, and 3.7-4.0 t / h of molten asphalt.

5. The method for comprehensive utilization of carbon tailings according to claim 1, characterized in that: The melted asphalt and the returned dust powder are used to produce the charcoal bowl filler, and the specific steps include the following: Step S1, kneading the tailings: first, use the ash conveying screw device to convey 70-90% of the return material dust powder by mass to the kneading pot; then, start the kneading device to dry mix for 10 minutes, and then use the roasting process flue gas to heat the barrel-removing device to heat 10-30% of the molten asphalt by mass, and convey the molten asphalt to the kneading pot through the asphalt pump; finally, at 80-120°C, knead for 15-25 minutes and then turn the kneaded tailings out of the pot; Step S2, tailings filling: the tailings kneaded in step S1 are put into the anode carbon bowl for standby use; Step S3, roasting of anode carbon bowl: the anode carbon bowl of step S2 is loaded into the roasting furnace for roasting, and the roasting furnace is subjected to a 192h heating curve, that is, the heating interval is divided into five sections: the first section is 290-580°C, the average heating rate is 9.1°C per hour, the required time is 32h, and the cumulative time is 32h; the second section is 580-890°C, the average heating rate is 4.8°C per hour, the required time is 64h, and the cumulative time is 96h; the third section is 890-1080°C, the average heating rate is 5.9°C per hour, the required time is 32h, and the cumulative time is 128h; the fourth section is 1080-1140°C, the average heating rate is 5°C per hour, the required time is 12h, and the cumulative time is 140h; the fifth section is 1140°C, heat preservation, the required time is 52h, and the cumulative time is 192h; Step S4, roasting the anode carbon bowl: the roasted carbon bowl is taken out and used as winter antifreeze and heat preservation fuel after cooling.

6. The method for comprehensive utilization of carbon tailings according to claim 5, characterized in that: In the step S1, first, the dust collecting powder of the return material with a mass percentage of 82% is transported to the kneading pot by using the ash conveying screw device; then, after starting the kneading device for dry mixing for 10 minutes, the molten asphalt with a mass percentage of 18% is heated by the roasting process flue gas heating barrel removal device, and the molten asphalt is transported to the kneading pot by the asphalt pump; finally, at 100°C, after kneading for 20 minutes, the kneading tail material is turned out of the pot.

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