A recarburizer and a method for preparing the same

Abstract

The present application belongs to the technical field of steel metallurgy, and particularly relates to a carburant and a preparation method thereof. The present application uses oxidized petroleum coke and a carburant and a preparation method thereof for modifying graphite as main raw materials, and cooperates with the joint use of carbon quantum dots and polyvinyl alcohol modified asphalt, so that the particle size and moisture of the carburant are effectively reduced, and meanwhile, good absorption rate can be ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of steel metallurgy, and particularly relates to a carburant and a preparation method thereof. BACKGROUND

[0002] Iron ore is a non-renewable resource. With the continuous development of society, a large number of cast iron, cast steel products and waste of steel products produced from iron ore are scattered in every corner of the society, wasting resources and polluting the environment. The carburant and silicon carbide are used as additive materials to adjust the chemical composition of castings, deoxidize and degas, and can also play an inoculation role, increase the crystallization core of the iron liquid, refine the grain, and achieve the purpose of improving the mechanical properties. The carburant is a carbon-containing substance added to make up for the carbon loss during steel smelting. In the smelting process of steel products, due to factors such as long smelting time, holding time and overheating time, the smelting loss of carbon elements in the iron liquid increases, resulting in a decrease in the carbon content in the iron liquid, which causes the carbon content in the iron liquid to be lower than the expected theoretical value. At this time, the carbon content in the steel liquid needs to be increased, so the carburant needs to be added.

[0003] A preparation method of a special carburant for steel smelting is disclosed in Chinese patent (publication number CN107739774B). The invention first uses petroleum coke as raw material, takes advantage of its porous nature, absorbs water, and then freezes and crushes to obtain petroleum coke powder. Then, a mixed acid solution prepared by mixing sulfuric acid, nitric acid and hydrogen peroxide is used as an oxidizing agent to oxidize the petroleum coke powder, which is dispersed in an ethylene glycol system. After refrigeration, a carbon sol-gel is formed. After centrifugal separation and drying, ultra-fine nano iron powder produced by reduction is adsorbed to obtain modified carbonized material. Finally, high-temperature heat treatment is carried out in an argon atmosphere to graphitize, thereby obtaining a special carburant for steel smelting. However, this patent does not solve the problems of the existing technology, such as the large particle size of the carburant, the high water content, and the poor absorption rate, which seriously affect its actual use.

[0004] Therefore, how to modify the main components of the carburant, reduce the particle size and water content of the carburant, and at the same time ensure good absorption rate, has become a direction that needs to be focused on. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a carburant and a preparation method thereof, which aims to solve the problems of the prior art, such as the large particle size of the carburant, the high water content, and the poor absorption rate.

[0006] The present application uses oxidized petroleum coke and modified graphite as the main raw materials, and cooperates with the use of carbon quantum dots and polyvinyl alcohol modified asphalt, which effectively reduces the particle size and water content of the carburant, and at the same time ensures good absorption rate.

[0007] The technical solutions adopted by the present application to solve the above technical problems are as follows:

[0008] In a first aspect of the present application, a preparation method of a recarburizer is provided, comprising the following steps:

[0009] Step S1: 10-14 parts of petroleum coke are added into 100-120 parts of hydrogen peroxide solution with a mass fraction of 30%, and then reacted at 80-90 DEG C for 6-8 hours; after the reaction is completed, the product is filtered, washed with deionized water, and dried to obtain the oxidized petroleum coke;

[0010] Step S2: 100-140 parts of the oxidized petroleum coke and 30-40 parts of graphite are mixed to obtain a mixture A by ultrasonic dispersion; then 10-20 parts of carbon quantum dots and 4-8 parts of pitch are added and stirred for 2-4 hours; and then the mixture is heated and treated, and naturally cooled to obtain a mixture B;

[0011] Step S3: the mixture B is subjected to rotary granulation, and then is placed at a temperature of 80-100 DEG C and a pressure of -0.06 to -0.08 MPa for 2-4 hours to obtain the recarburizer.

[0012] The oxidized petroleum coke is treated by using hydrogen peroxide solution, which can remove the surface impurities of the petroleum coke, improve the purity of the petroleum coke, and change the surface characteristics of the petroleum coke, so that the petroleum coke is more easily crushed in the subsequent processing process, thereby reducing the particle size of the recarburizer.

[0013] As a preferred technical scheme of the present application, the heat treatment conditions include that the heat treatment temperature is 1800-2000 DEG C, and the heat treatment time is 8-10 hours.

[0014] As a preferred technical scheme of the present application, the graphite is modified graphite; and a preparation method of the modified graphite comprises the following steps: 10-14 parts of phenolic resin are added into 260-300 parts of anhydrous ethanol and ultrasonically dispersed for 40-60 minutes; then 140-150 parts of fluorinated graphite and 100-120 parts of deionized water are added and stirred for 2-4 hours; and then the product is dried to obtain the modified graphite.

[0015] As a preferred technical scheme of the present application, the preparation method of the fluorinated graphite comprises the following steps: 10-20 parts of graphite are placed in a nitrogen atmosphere, and pretreated at 450-550 DEG C for 20-40 minutes; then mixed gas is continuously introduced for fluorination for 6-8 hours; after the fluorination is completed, the sample is washed with deionized water, and dried to obtain the fluorinated graphite.

[0016] As a preferred technical scheme of the present application, the particle size of the graphite is 2-4 microns.

[0017] As a preferred technical scheme of the present application, the mixed gas is nitrogen and fluorine; and the volume ratio of the nitrogen and fluorine is (9-10):1.

[0018] The fluorine atoms on the surface of the modified graphite can significantly improve the hydrophobicity of the material and reduce water adsorption, which helps to prevent the carbon additive from absorbing moisture in the environment, thereby maintaining a low water content.

[0019] As a preferred technical solution of the present application, the preparation method of the carbon quantum dots comprises: uniformly laying 2-4 parts of citric acid on the bottom of a beaker in terms of weight, and performing a heating reaction in a vacuum drying box; after the heating reaction is completed, the solid is naturally cooled to room temperature, then 10-14 parts of a sodium hydroxide solution with a molar concentration of 1 mol / L is added to the solid, and the mixture is stirred uniformly, and then the carbon quantum dots are obtained through dialysis, freeze-drying and grinding.

[0020] As a preferred technical solution of the present application, the temperature of the heating reaction is 180-200 DEG C, and the time is 1-2 h.

[0021] The carbon quantum dots have a very high specific surface area, which can significantly increase the total surface area of the carbon additive and improve the contact area between the carbon additive and the target substance, thereby enhancing the absorption effect; at the same time, the introduction of carbon quantum dots can adjust the microstructure of the carbon additive and form a pore structure that is more conducive to the transmission and reaction of substances, thereby comprehensively improving the absorption rate of the carbon additive.

[0022] As a preferred technical solution of the present application, the asphalt is polyvinyl alcohol modified asphalt; and the preparation method of the polyvinyl alcohol modified asphalt comprises: adding 10-20 parts of polyvinyl alcohol to 100-160 parts of deionized water to dissolve thoroughly, then adding 40-50 parts of asphalt, stirring at 150-160 DEG C for 20-30 min, and then keeping the temperature at 160-180 DEG C for 50-60 min to obtain the polyvinyl alcohol modified asphalt.

[0023] The polyvinyl alcohol modified asphalt can further improve the fluidity of the asphalt, so that the binder asphalt can more easily penetrate between the carbon additive particles before heat treatment, and form a carbon skeleton after heat treatment, thereby increasing the contact between the carbon additive and the target substance and improving the absorption rate.

[0024] In a second aspect, the present application provides a carbon additive prepared by the method of the first aspect.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] (1) The present application uses polyvinyl alcohol modified asphalt as a binder, which can uniformly bond oxidized petroleum coke, modified graphite and carbon quantum dots together, and form a high-density carbon network after heat treatment, thereby reducing the particle size of the carbon additive, reducing the moisture content, and improving the absorption rate through the comprehensive action of multiple components.

[0027] (2) The oxidized petroleum coke of the present application can remove the surface impurities of the petroleum coke, improve its purity, and also make it easier to be crushed in the subsequent processing process by changing the surface properties of the petroleum coke, thereby reducing the particle size of the carburant.

[0028] (3) The modified graphite of the present application can significantly improve the hydrophobicity of the material by fluorination treatment of the graphite, reduce water adsorption, and this property helps to prevent the carburant from absorbing moisture in the environment, thereby maintaining a lower water content.

[0029] (4) The carbon quantum dots of the present application have a very high specific surface area, which can significantly increase the total surface area of the carburant, improve the contact area between the carburant and the target substance, and thereby enhance the absorption effect; at the same time, the introduction of carbon quantum dots can adjust the microstructure of the carburant to form a pore structure that is more conducive to the transmission and reaction of substances, thereby improving the absorption rate of the carburant.

[0030] (5) The polyvinyl alcohol modified asphalt of the present application can further improve the fluidity of the asphalt, making it easier for the binder asphalt to penetrate between the carburant particles before heat treatment, and form a carbon skeleton after heat treatment, increasing the contact between the carburant and the target substance, and thereby improving the absorption rate. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present application, the present application is illustrated by the following examples. It should be understood by those skilled in the art that the examples are only to help understand the present application and should not be regarded as a specific limitation on the present application.

[0032] Some components in the examples and comparative examples are as follows:

[0033] Petroleum coke, model CK9-Z, purchased from Jinzhou Petrochemical Company of China Petroleum;

[0034] Graphite I, model TS-4, particle size 3 μm, purchased from Qingdao Tianyuan Graphite Co., Ltd.;

[0035] Graphite II, item number G434785, particle size 30 μm, purchased from Shanghai Aldrich Biochemical Technology Co., Ltd.;

[0036] Graphite III, item number XT-0801-24-1, particle size 50 nm, purchased from Shanghai Xiangtian Nanometer Material Co., Ltd.;

[0037] Activated carbon powder, CAS number 7440-44-0, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0038] Asphalt, item number 10, purchased from Jinan Chenfu Chemical Co., Ltd.;

[0039] Hydrogen peroxide, item number H639762, purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0040] Phenolic resin, model CQCN700, purchased from Shandong Shengquan Chemical Co., Ltd.

[0041] Anhydrous ethanol, CAS number 64-17-5, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0042] Citric acid, CAS number 77-92-9, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0043] Sodium hydroxide, CAS number 1310-73-2, purchased from National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0044] Polyvinyl alcohol, item number P139540, purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0045] Preparation of modified graphite: (1) 20 parts of graphite I (particle size of 3 μm) were pretreated under a nitrogen atmosphere at 550℃ for 20 min, and then fluorinated by continuously passing a mixed gas (volume ratio of nitrogen to fluorine was 9:1) for 8 h. After fluorination, the sample was washed with deionized water and dried to obtain the fluorinated graphite.(2) 14 parts of phenolic resin were added to 300 parts of anhydrous ethanol and ultrasonically dispersed for 60 min, then 150 parts of fluorinated graphite and 120 parts of deionized water were added and stirred for 4 h, and then dried to obtain the modified graphite.

[0046] Preparation of carbon quantum dots: 4 parts of citric acid were evenly spread on the bottom of a beaker, and a heating reaction was carried out in a vacuum drying oven (temperature was 200℃, time was 1 h); after the heating reaction was completed, the solid was naturally cooled to room temperature, then 14 parts of a sodium hydroxide solution with a molar concentration of 1 mol / L was added, stirred uniformly, and then subjected to dialysis, freeze-drying and grinding to obtain the carbon quantum dots.

[0047] Preparation of polyvinyl alcohol modified asphalt: 20 parts of polyvinyl alcohol were added to 160 parts of deionized water and dissolved thoroughly, then 50 parts of asphalt were added and stirred at 160℃ for 30 min, and then kept at 180℃ for 50 min to obtain the polyvinyl alcohol modified asphalt.

[0048] Example 1

[0049] The present embodiment provides a preparation method of a carburant, comprising the following steps:

[0050] Step S1: 14 parts of petroleum coke were added into 120 parts of hydrogen peroxide solution with a mass fraction of 30%, and then reacted at 90°C for 6h, after the reaction was completed, the product was filtered, washed with deionized water and dried to obtain the oxidized petroleum coke;

[0051] Step S2: 140 parts of the oxidized petroleum coke and 40 parts of modified graphite were mixed to obtain a mixture A by ultrasonic dispersion, then 20 parts of carbon quantum dots and 8 parts of polyvinyl alcohol modified asphalt were added and stirred for 4h, and then heat treatment was carried out at a heat treatment temperature of 2000°C and a heat treatment time of 8h, and then naturally cooled to obtain a mixture B;

[0052] Step S3: the mixture B was subjected to rotary table granulation, and then was placed at a temperature of 100°C and a pressure of-0.08MPa for 2h to obtain the carbon additive.

[0053] Example 2

[0054] The embodiment provides a preparation method of a carbon additive, comprising the following steps:

[0055] Step S1: 10 parts of petroleum coke were added into 100 parts of hydrogen peroxide solution with a mass fraction of 30%, and then reacted at 80°C for 8h, after the reaction was completed, the product was filtered, washed with deionized water and dried to obtain the oxidized petroleum coke;

[0056] Step S2: 100 parts of the oxidized petroleum coke and 30 parts of modified graphite were mixed to obtain a mixture A by ultrasonic dispersion, then 10 parts of carbon quantum dots and 4 parts of polyvinyl alcohol modified asphalt were added and stirred for 2h, and then heat treatment was carried out at a heat treatment temperature of 1800°C and a heat treatment time of 10h, and then naturally cooled to obtain a mixture B;

[0057] Step S3: the mixture B was subjected to rotary table granulation, and then was placed at a temperature of 80°C and a pressure of-0.06MPa for 4h to obtain the carbon additive.

[0058] Example 3

[0059] The embodiment provides a preparation method of a carbon additive, comprising the following steps:

[0060] Step S1: 12 parts of petroleum coke were added into 110 parts of hydrogen peroxide solution with a mass fraction of 30%, and then reacted at 85°C for 7h, after the reaction was completed, the product was filtered, washed with deionized water and dried to obtain the oxidized petroleum coke;

[0061] Step S2: 120 parts of the oxidized petroleum coke and 35 parts of modified graphite were mixed by weight parts, ultrasonic dispersion to obtain a mixture A, then 15 parts of carbon quantum dots and 6 parts of polyvinyl alcohol modified asphalt were added and stirred for 3 h, and then heat treatment was carried out by increasing the temperature (heat treatment temperature was 1900℃, heat treatment time was 9 h), and then natural cooling was carried out to obtain a mixture B;

[0062] Step S3: The mixture B was subjected to rotary table granulation, and then was placed at a temperature of 90℃ and a pressure of -0.07 MPa for 3 h to obtain a carburizing agent.

[0063] Comparative Example 1

[0064] The comparative example provides a preparation method of a carburizing agent, which is different from the example 1 in that a commercially available petroleum coke is used instead of the oxidized petroleum coke.

[0065] Comparative Example 2

[0066] The comparative example provides a preparation method of a carburizing agent, which is different from the example 1 in that a commercially available graphite I is used instead of the modified graphite.

[0067] Comparative Example 3

[0068] The comparative example provides a preparation method of a carburizing agent, which is different from the example 1 in that the graphite II is used instead of the graphite I to prepare the modified graphite.

[0069] Comparative Example 4

[0070] The comparative example provides a preparation method of a carburizing agent, which is different from the example 1 in that the graphite III is used instead of the graphite I to prepare the modified graphite.

[0071] Comparative Example 5

[0072] The comparative example provides a preparation method of a carburizing agent, which is different from the example 1 in that a commercially available activated carbon powder is used instead of the carbon quantum dots.

[0073] Comparative Example 6

[0074] The comparative example provides a preparation method of a carburizing agent, which is different from the example 1 in that a commercially available asphalt is used instead of the polyvinyl alcohol modified asphalt.

[0075] The performance of the carburizing agents provided by the above examples and comparative examples was tested, and the test method was as follows:

[0076] (1) Particle size test

[0077] The test was carried out according to the requirements of “JB / T 14236-2023 Carburizing Agent for Foundry”.

[0078] (2) Moisture test

[0079] Test according to the requirements of JB / T 14236-2023 Carbon additive for casting.

[0080] (3) Carbon additive absorption rate test

[0081] The carbon additive was laid in a medium-frequency induction furnace at an addition amount of 0.5%, then scrap iron was added, heated to melt the scrap iron into iron liquid, when the temperature reached 1500℃, the slag was removed after stirring uniformly with a rolling stick, and the absorption rate of the carbon additive was detected by pre-furnace spectral analysis.

[0082] The performance test data are shown in Table 1.

[0083] Table 1 Performance test results

[0084] Particle size (mm) Moisture (%) Carburizer absorption rate (%) Example 1 1.2 0.35 92.3 Example 2 1.7 0.41 91.4 Example 3 1.4 0.38 91.9 Comparative Example 1 3.9 1.17 83.6 Comparative Example 2 3.7 1.22 83.9 Comparative Example 3 2.8 0.76 87.1 Comparative Example 4 2.5 0.73 87.5 Comparative Example 5 3.5 1.13 83.2 Comparative Example 6 3.8 1.09 82.7

[0085] As can be seen from the above, the carbon additive (Examples 1-3) is prepared by using oxidized petroleum coke and modified graphite as main raw materials, and using carbon quantum dots and polyvinyl alcohol modified asphalt together, the particle size is 1.2-1.7mm, the moisture is 0.35-0.41%, and the absorption rate of the carbon additive is 91.4-92.3%.

[0086] Compared with Example 1, using commercially available petroleum coke instead of oxidized petroleum coke, the particle size of the carbon additive becomes larger, the moisture increases, and the absorption rate decreases (Comparative Example 1); compared with Example 1, using commercially available graphite I instead of modified graphite, the particle size of the carbon additive becomes larger, the moisture increases, and the absorption rate decreases (Comparative Example 2); compared with Example 1, using graphite II instead of graphite I to prepare modified graphite, because the particle size of graphite II is too large, the modification effect is not good, the particle size of the carbon additive becomes larger, the moisture increases, and the absorption rate decreases (Comparative Example 3); compared with Example 1, using graphite III instead of graphite I to prepare modified graphite, because the particle size of graphite III is too small, the modification effect is not good, the particle size of the carbon additive becomes larger, the moisture increases, and the absorption rate decreases (Comparative Example 4); compared with Example 1, using commercially available activated carbon powder instead of carbon quantum dots, the particle size of the carbon additive becomes larger, the moisture increases, and the absorption rate decreases (Comparative Example 5); compared with Example 1, using commercially available asphalt instead of polyvinyl alcohol modified asphalt, the particle size of the carbon additive becomes larger, the moisture increases, and the absorption rate decreases (Comparative Example 6).

[0087] In summary, by using oxidized petroleum coke and modified graphite as main raw materials, and using carbon quantum dots and polyvinyl alcohol modified asphalt together, the particle size and moisture of the carbon additive are effectively reduced, and at the same time, good absorption rate can be ensured.

Claims

1. A method for the preparation of a recarburizer, Characterized in that It comprises the following steps: Step S1: 10-14 parts of petroleum coke are added to 100-120 parts of 30% hydrogen peroxide solution by weight, then reacted at 80-90℃ for 6-8h, after the reaction is completed, it is filtered, washed with deionized water and dried to obtain oxidized petroleum coke; Step S2: 100-140 parts of the oxidized petroleum coke and 30-40 parts of modified graphite are mixed by weight to obtain mixture A by ultrasonic dispersion, then 10-20 parts of carbon quantum dots and 4-8 parts of polyvinyl alcohol modified asphalt are added and stirred for 2-4h, and then heated and treated, and naturally cooled to obtain mixture B; Step S3: The mixture B is subjected to rotary granulation, and then is placed at a temperature of 80-100℃ and a pressure of-0.06 to-0.08MPa for 2-4h to obtain a carbon additive; The preparation method of the modified graphite comprises: 10-20 parts of graphite are placed in a nitrogen atmosphere, pretreated at 450-550℃ for 20-40min, and then continuously fluorinated by mixed gas for 6-8h, after the fluorination is completed, the sample is washed with deionized water and dried to obtain fluorinated graphite; 10-14 parts of phenolic resin are added to 260-300 parts of anhydrous ethanol and ultrasonically dispersed for 40-60min, then 140-150 parts of fluorinated graphite and 100-120 parts of deionized water are added and stirred for 2-4h, and dried to obtain modified graphite; The particle size of the graphite is 2-4μm; The preparation method of the polyvinyl alcohol modified asphalt comprises: 10-20 parts of polyvinyl alcohol are added to 100-160 parts of deionized water and dissolved, then 40-50 parts of asphalt are added and stirred at 150-160℃ for 20-30min, and then heated and treated at 160-180℃ for 50-60min to obtain the polyvinyl alcohol modified asphalt.

2. The preparation method of the carbon additive according to claim 1, characterized in that The heat treatment conditions comprise: a heat treatment temperature of 1800-2000℃ and a heat treatment time of 8-10h.

3. The preparation method of the carbon additive according to claim 1, characterized in that The mixed gas is nitrogen and fluorine gas; the volume ratio of the nitrogen and fluorine gas is (9-10):

1.

4. The preparation method of the carbon additive according to claim 1, characterized in that The preparation method of the carbon quantum dots comprises: 2-4 parts of citric acid are uniformly spread on the bottom of a beaker, and heated and reacted in a vacuum drying box; after the heating and reaction is completed, the solid is naturally cooled to room temperature, then 10-14 parts of 1mol / L sodium hydroxide solution is added to the solid, stirred uniformly, and subjected to dialysis, freeze-drying and grinding to obtain the carbon quantum dots.

5. The preparation method of the carbon additive according to claim 4, characterized in that The heating reaction temperature is 180-200℃, and the time is 1-2h.

6. A recarburizer characterized by ， Prepared according to any one of the methods of claims 1-5.