Preparation method of iron-carbon composite furnace charge and iron-carbon composite furnace charge

Abstract

The application provides a preparation method of iron-carbon composite furnace charge and the iron-carbon composite furnace charge and belongs to the technical field of metallurgical processes. The iron-carbon composite furnace charge provided by the application comprises the following raw materials in parts by weight: non-coking coal powder 61-84 parts; iron oxide 10-30 parts; high-temperature accelerator 6-9 parts; hot water 8-12 parts; the preparation method comprises the following steps: after the raw materials are uniformly mixed, the mixed materials are pelletized to obtain pellet materials; the pellet materials are subjected to segmented carbonization at 650 DEG C-1050 DEG C; the pellet materials after carbonization are directly sprayed and cooled to obtain the iron-carbon composite furnace charge. The non-coking coal is not as good as the coking coal in terms of cohesiveness, and the high-temperature strength is low, so it is difficult to be applied in blast furnaces. In the application, the iron oxide is added in the non-coking coal, the particle size of the furnace charge is changed, and the carbonization treatment is carried out in a non-direct roasting furnace to form the iron-carbon composite furnace charge which can replace the coking coal. The application meets the national conditions that the non-coking coal reserves are rich in China, solves the technical problem of insufficient energy storage of the coking coal, reduces the cost, and the carbon emission reduction reaches more than 10%.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metallurgical process, and particularly relates to a preparation method of iron-carbon composite furnace charge and the iron-carbon composite furnace charge. BACKGROUND

[0002] As the main process facility of metallurgy, blast furnace has been used for more than 200 years. Its high efficiency of energy exchange promotes its popularization, boosts the progress and development of the society, and plays a huge role in the national economy. The reducing agent used in blast furnace, i.e. coke, becomes an indispensable furnace charge in ironmaking process. The strength of coke plays a role of skeleton supporting the furnace charge in the blast furnace, and the high-strength coke in the blast furnace bosh filters the iron liquid; high fixed carbon content is the main reducing agent of iron oxides, and whether it is the upper indirect reduction reaction or the blast furnace bosh direct reduction reaction, it cannot do without the carbon in the coke; the coke has high calorific value, and the reduction reaction releases a large amount of heat, which becomes the heat that cannot be separated from pyrometallurgy.

[0003] With the rapid development of economy, as the main smelting means of metallurgy, it contributes to the basic materials at the same time, and a large amount of carbon emission brings environmental impact. The steel industry accounts for 16% of industrial carbon emissions, and 70% of carbon emissions of the steel industry is in the ironmaking process, so the adjustment of the furnace charge structure of the blast furnace process is the key link of energy saving and emission reduction. In addition, the calcination of coke depends on high-quality caking coal, and the proportion of coking coal in coal is about 5.9%, which is not enough to meet the needs of blast furnace ironmaking. Large-scale blast furnaces need higher quality coke, and the production of coke itself also has a huge impact on the environment. Global warming and the shortage of high-quality resources limit the production of coke, which has become the consensus of many countries. Coke has become a difficult link in the ironmaking process.

[0004] The proven Jurassic coalfield coal quality belongs to low ash, low sulfur, low phosphorus, high volatile matter, and medium-high calorific value long flame coal and non-caking coal, and the reserves account for 39.6% of the proven coal reserves, which is an ideal raw material for coal dry distillation and a high-quality raw material for coal chemical industry. In recent years, it has made great progress. The Jurassic coalfield reserves are the most abundant, mainly concentrated in North China and Northwest China. The famous coalfields mainly include the Sheng-Fu, Dongsheng, Datong coalfields and the undeveloped coalfields in Xinjiang. The proven reserves are 134.94 million tons, and the coal types mainly include long flame coal, non-caking coal and weakly caking coal. The commonly mentioned Sheng-Fu coalfield refers to the Jurassic coalfield. Because the Jurassic coal does not have good caking property like coking coal, it cannot be calcined at high temperature to prepare coke like coking coal. Even the part with weak caking property can only be made into semi-coke (commonly known as semi-coke), which is easy to break due to its low strength. Except for a small part of it used in small blast furnaces, it cannot be used in 1000m 3 The above blast furnaces cannot be used at all.

[0005] Therefore, how to achieve the ultimate energy efficiency in the short term, how to alleviate the pressure of using coke in blast furnace, and how to seek low-carbon path of coke substitute have become the object of pursuit.

[0006] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in the art. SUMMARY

[0007] In order to solve the technical problems of large demand and insufficient supply of traditional blast furnace reducing agent coke in the prior art, a preparation method of iron-carbon composite charge and iron-carbon composite charge are provided.

[0008] The first aspect of the application provides a preparation method of iron-carbon composite charge, the iron-carbon composite charge comprises the following raw materials by weight:

[0009] Non-coking coal powder 61-84 parts;

[0010] Iron oxide 10-30 parts;

[0011] High-temperature accelerator 6-9 parts;

[0012] Hot water 8-12 parts.

[0013] In some embodiments, the high-temperature accelerator is high-temperature pitch powder and / or high-temperature coal tar.

[0014] Unlike traditional cold binders, the high-temperature accelerator used in the application itself is a binder, reducing agent, and high-temperature enhancer. The high-temperature accelerator plays a binding role at cold state, and at high temperature, it itself is a volatile C and H compound that releases in the form of CO or H2. These reducing atmospheres facilitate the reaction of surrounding fine particles of iron oxide, reducing the iron oxide to Fe, and excessive C is dry distilled to form a hard and high-temperature-resistant fixed carbon, ensuring the high-temperature strength of the iron-carbon material.

[0015] The high temperature is understood as the pitch powder with a ring and ball softening point of 95-120℃.

[0016] In some embodiments, the temperature of the hot water is ≥80℃. Water with a temperature of 80℃ or higher is beneficial to promote the toughness of the mixture, achieve the effect of difficult material, and improve the forming rate during ball pressing.

[0017] In some embodiments, the non-coking coal powder is one or more of long flame coal, non-caking coal, weakly caking coal. In October 1989, the State Standardization Administration issued the National Standard for Classification of Chinese Coal (GB5751-86), which classifies coal into 14 categories, namely lignite, long flame coal, non-caking coal, weakly caking coal, 1 / 2 medium caking coal, gas coal, gas-fat coal, 1 / 3 coking coal, fat coal, coking coal, lean coal, lean coal, lean coal, and anthracite. The present application mainly utilizes weakly caking coal with poor coal genesis, low or medium coalification degree, which has very poor caking property and cannot be used for coking alone. Due to its special genesis, weakly caking coal has a high content of inert group. Typical weakly caking coal is produced in Datong City, Shanxi Province. Non-caking coal: has been oxidized at the early stage of coalification, so it has the characteristics of low calorific value. It is mainly used for power generation, gasification and domestic fuel, etc. Non-caking coal is mainly produced in the northwest region of China. Long flame coal: has the lowest coalification degree among all bituminous coals. It is called long flame coal because of its long flame during combustion. It is mainly used for power generation, power station boiler fuel, etc. The long flame coal reserves in Liaoning Province are the largest in the country. Lignite: the lowest grade of all coals, characterized by high moisture and high oxygen content (about 15%-30%), and containing some humic acid. It is mainly used for power generation and gasification.

[0018] In some embodiments, the particle size of the non-coking coal powder is -200 mesh;

[0019] and / or, the particle size of the iron oxide is -300 mesh;

[0020] and / or, the particle size of the high-temperature promoter is -200 mesh.

[0021] Wherein, -200 mesh means 200 mesh or less, -300 mesh means 300 mesh or less.

[0022] In some embodiments, the iron oxide includes one or more of iron oxide powder, iron ore powder, concentrate powder, fine ore after magnetic separation, Fe2O3 hematite powder not easy to be magnetically separated, and Fe3O4 magnetite powder that can be magnetically separated.

[0023] In some embodiments, the method for preparing the iron-carbon composite charge includes:

[0024] After the raw materials are uniformly mixed, the mixed materials are pelletized to obtain pellet materials;

[0025] The pellet materials are carbonized at 650°C-1050°C;

[0026] The pellet materials after carbonization are directly water-cooled to obtain the iron-carbon composite charge.

[0027] In some embodiments, the pressure for pelletizing is ≥500N;

[0028] The shape of the ball material after balling is not limited, and the ball material can be spherical, olive-shaped, rhombic, oval, quadrangular, etc., so that the ball material can be easily demolded and produced.

[0029] In some embodiments, the carbonization comprises high-temperature carbonization or low-temperature carbonization.

[0030] The carbonization temperature of the high-temperature carbonization is 850-1050 DEG C, and the time is 2.5-4h.

[0031] The carbonization temperature of the low-temperature carbonization is 650 DEG C-850 DEG C, and the time is 3.5-5h.

[0032] The purpose of carbonization is to remove the original volatile components of the material, and the main components of the volatile components are CO and H2. x The high-concentration reducing gas is removed at the same time as FeO

[0033] The second aspect of the application provides an iron-carbon composite charge, which is prepared by the preparation method.

[0034] Preferably, the composition of the iron-carbon composite charge is as follows:

[0035]

[0036] Wherein, TFe is the total iron content.

[0037] In order to compensate for the poor high-temperature cohesiveness of non-coking coal (such as Jurassic coal) and the defect that it cannot be formed in a cold state, the application uses the method of adding iron oxide to the material and changes the particle size of the charge to perform carbonization treatment in a non-directly-fired furnace to form the iron-carbon composite charge.

[0038] In some embodiments, the Jurassic coal with ash content of less than or equal to 12% is ground by a pulverizer to a fine powder with a particle size of more than 80% of -200 mesh, the moisture is based on the smooth production of grinding (generally moisture < 8%), the particle size of the iron oxide powder or concentrate powder is less than or equal to 300 mesh, and the high-temperature carbonization promoter also reaches less than or equal to 200 mesh. After the three materials are weighed according to the weight ratio of 61-84 parts of coal powder, 10-30 parts of iron oxide, and 6-9 parts of high-temperature promoter, 300 kg of each batch is added to a strong mixer, 8-12 parts of water at 80°C is additionally added, and the mixture is mixed for 3-5 minutes. The material is then added to a roller-type ball press for balling, and the ball mill diameter is preferably 30-60 mm and the thickness is 20 mm. The pressed ball material can be additionally stacked or directly dried in a drying kiln and then carbonized in a rotary kiln carbonization chamber. The ball material is carbonized in a carbonization kiln at a temperature of 650°C-1050°C for 2 hours at high temperature and 3 hours at low temperature. After carbonization, the material is directly sprayed with water for cooling, and the finished product of iron-carbon composite furnace charge is obtained after cooling.

[0039] Water at a temperature of more than 80°C is beneficial to promote the toughness of the mixture, achieve the effect of difficult material, ensure that the forming rate is more than 90% and the strength is greater than or equal to 500N during ball pressing. The coal powder and iron powder are fully mixed in the strong mixer to ensure that the organic volatile matter of the coal powder is rapidly decomposed, a reducing atmosphere is generated, and FeO x reacts to ensure that the reduction reaction can be carried out from the inside to the outside, the voids left after the decomposition and escape of the coal powder are filled with the overflow of the high-temperature promoter, the vacancies are filled, and the ball material is not loose. The FeO x that is reduced forms a hinge with the metal Fe and C, which strengthens the high-temperature strength of the ball material, and the metal Fe is solidly wrapped by a large amount of C, which can ensure that the metal Fe does not collapse in the blast furnace at a certain high temperature, and the high-temperature effect of the coke is achieved. The generated metal Fe catalyzes CO+FeO x =Fe+CO2 at the indirect reduction reaction site of the blast furnace, which reduces the reaction temperature and achieves the purpose of energy saving and emission reduction.

[0040] Compared with the prior art, the technical effects achieved by the present application are as follows:

[0041] (1) Non-coking coal does not have good cohesiveness like coking coal, has low high-temperature strength, and is difficult to apply in a blast furnace. In the present application, iron oxide is added to non-coking coal, the particle size of the furnace charge is changed, and carbonization treatment is carried out in a non-direct roasting furnace to form a one-time shape, so that iron-carbon composite furnace charge that can replace coking coal is obtained, the cost is low, the raw materials are widely selected, and the defects of the shortage of coking coal can be made up. The furnace charge itself can reduce the indirect reduction reaction temperature, reduce the comprehensive consumption, and reduce the carbon emission amount.

[0042] (2) the present application adds hot water above 80 DEG C in the material, is favorable to promote the toughness of mixing material, reaches the effect of difficult material, combines certain required pressure (above 500N), guarantees the forming rate of 90% or more when pressing ball.

[0043] (3) the present application guarantees that the mixed material is fully mixed in the mixer to ensure that the organic volatile matter of coal powder is rapidly decomposed, the reducing atmosphere generated is reacted with FeO x , and the reduction reaction can be carried out from inside to outside, the space left by the decomposition and escape of coal powder is filled by the overflow of high-temperature accelerant, the vacancy is filled, and the sintered ball is avoided to be loose, and the FeO x being reduced generates metal Fe and C to form a hinge, which strengthens the high-temperature strength of the sintered ball, and the metal Fe is solidly wrapped by a large amount of C, which can guarantee not to be disassembled at a certain high temperature in the blast furnace, and the high-temperature effect of coke is achieved.

[0044] (4) the metal Fe generated in the reduction reaction plays a catalytic role on CO+FeO x =Fe+CO2 in the indirect reduction reaction part of the blast furnace, which reduces the reaction temperature and achieves the purpose of energy saving and emission reduction.

[0045] (5) through laboratory simulation test verification, the iron-carbon composite furnace charge prepared by the present application can replace 10% to 30% of the coke used in the blast furnace, because a large amount of non-caking coking coal is used, the cost is 300 yuan lower than that of the traditional coking coal, and because the metal Fe contained in the product plays a catalytic role in the indirect reduction reaction of the blast furnace, the comprehensive energy consumption is reduced, and the carbon emission reduction is more than 10%. 0.5 tons of coke are needed for each ton of molten iron, and the annual output of molten iron in China is nearly 1 billion tons, so the annual consumption of coke is 500 million tons, if 10% is replaced, the iron-carbon composite furnace charge is 50 million tons, and 15 billion yuan of cost is saved every year. The product will become a low-carbon and green environmental protection furnace charge, and can provide a possibility for solving the problem of coke for steel. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is a schematic flow chart of the iron-carbon composite furnace charge in the present application;

[0047] Figure 2 is a photo of the iron-carbon composite furnace charge prepared in example 1 of the present application;

[0048] Figure 3 is an enlarged photo of a single product of the iron-carbon composite furnace charge prepared in example 1 of the present application;

[0049] Figure 4 is an AFM graph of the iron-carbon composite furnace charge prepared in example 1 of the present application;

[0050] Figure 5 is a photo of the iron-carbon composite furnace charge prepared in example 2 of the present application;

[0051] Figure 6 is a cross-section photo of the iron-carbon composite burden prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0052] The technical solutions of the present application are described below by specific examples in combination with the drawings. It should be understood that the one or more steps mentioned in the present application do not exclude other methods and steps before or after the combination steps, or other methods and steps can be inserted between the explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Unless otherwise specified, the numbering of the steps of each method is only for the purpose of identifying the steps of each method, and not to limit the arrangement order of each method or to limit the scope of the implementation of the present application. The change or adjustment of the relative relationship, without substantial technical content change, can also be considered as the implementation scope of the present application.

[0053] The raw materials and instruments used in the examples are not specifically limited in source, and can be purchased in the market or prepared according to the conventional methods well known to those skilled in the art.

[0054] The processing and manufacturing schematic flow chart of the iron-carbon composite burden provided by the present application is shown in Figure 1 As shown in the figure, after the non-coking coal, iron ore powder and high-temperature accelerator are proportioned, hot water is put into a strong mixer for rapid mixing, and then the mixed coal balls are directly put into a preheating bin after being formed by a strong roller balling machine. After preheating, the mixed coal balls are sent into a sleeve type rotary kiln outer wall carbonization chamber, and the inner cylinder of the rotary kiln serves as a heating energy source. The heat energy comes from the volatile coal gas generated by the decomposition of the ball material, which is input into the rotary kiln inner shell high-temperature flue gas pipe after being burned in the combustion chamber. The heat waste gas discharged is used for preheating and drying of the raw material balls. In order to avoid the temperature of the high-temperature flue gas pipe exceeding the set value, a cold air distribution system is provided beside to adjust and stabilize the temperature in the high-temperature pipe. When the carbonized ball material is discharged, it is quickly cooled by water spraying, and the iron-carbon composite burden with smooth surface, homogeneity and no loss on ignition defects is obtained, and the composition is as follows:

[0055]

[0056] Among them, TFe is the total iron content.

[0057] Example 1

[0058] A preparation method of an iron-carbon composite burden:

[0059] Mix the materials in the following proportions:

[0060] Jurassic coal powder: 64 parts;

[0061] Iron ore powder: 30 parts;

[0062] High-temperature pitch powder: 6 parts;

[0063] 80℃ hot water: 10 parts;

[0064] Wherein, the particle size of Jurassic coal powder and high temperature pitch powder is -200 mesh, the particle size of iron ore powder is -300 mesh, the balling pressure is 500N, and the obtained ball material is dried, and then is baked at 950℃ for 2.5 hours without contacting oxygen to obtain the finished product iron-carbon composite burden as shown in Figure 2 、 Figure 3 .

[0065] The compressive strength of the above iron-carbon composite burden is 3550N, the tumbler strength ID is 78%, and the reactivity CRI is 68% through testing. Figure 4 is the AFM image of the iron-carbon composite burden prepared in the embodiment, and from the image, it can be seen that the reduced FeOx produces metal Fe and C to form a hinge, and the metal iron is solidly wrapped by a large amount of C.

[0066] Embodiment 2

[0067] A preparation method of an iron-carbon composite burden:

[0068] Mix the materials in the following proportions:

[0069] Jurassic coal powder: 66 parts;

[0070] Iron ore powder: 25 parts;

[0071] High temperature pitch powder: 9 parts;

[0072] 90℃ hot water: 10 parts;

[0073] Wherein, the particle size of Jurassic coal powder and high temperature pitch powder is -300 mesh, the particle size of iron ore powder is -300 mesh, the balling pressure is 600N, and the obtained ball material is dried, and then is baked at 650℃ for 4.0 hours without contacting oxygen to obtain the finished product iron-carbon composite burden as shown in Figure 5 、 Figure 6 .

[0074] The compressive strength of the above iron-carbon composite burden is 3350N, the tumbler strength ID is 72%, and the reactivity CRI is 66% through testing.

[0075] Embodiment 3

[0076] A preparation method of an iron-carbon composite burden:

[0077] Mix the materials in the following proportions:

[0078] Jurassic coal powder: 84 parts;

[0079] Iron ore powder: 10 parts;

[0080] High temperature pitch powder: 9 parts;

[0081] 80℃ hot water: 12 parts;

[0082] Wherein, the particle size of Jurassic coal powder and high temperature pitch powder is -200 mesh, the particle size of iron ore powder is -300 mesh, the balling pressure is 500N, the obtained ball material is dried, and then is baked at 1050℃ for 2.5 hours without contacting oxygen to obtain the finished product of iron-carbon composite furnace charge.

[0083] Test results show that the compressive strength of the finished product of iron-carbon composite furnace charge is greater than 3200N, and the drum strength is greater than 75%.

[0084] Example 4

[0085] A preparation method of an iron-carbon composite furnace charge:

[0086] Mix the materials in the following proportions:

[0087] Jurassic coal powder: 72 parts;

[0088] Iron ore powder: 20 parts;

[0089] High temperature pitch powder: 8 parts;

[0090] 80℃ hot water: 8 parts;

[0091] Wherein, the particle size of Jurassic coal powder and high temperature pitch powder is -200 mesh, the particle size of iron ore powder is -300 mesh, the balling pressure is 500N, the obtained ball material is dried, and then is baked at 750℃ for 4 hours without contacting oxygen to obtain the finished product of iron-carbon composite furnace charge.

[0092] Test results show that the compressive strength of the finished product of iron-carbon composite furnace charge is greater than 3200N, and the drum strength is greater than 75%.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 is that no water is added.

[0095] Results: During the balling process, the material is difficult to form.

[0096] Comparative Example 2

[0097] The difference between this comparative example and Example 1 is that the added water is normal temperature water.

[0098] Results: Compared with Comparative Example 1, the forming of this comparative example is relatively good, but the forming rate is still low, less than 50%, and the transfer process is easy to break and difficult to operate.

[0099] Comparative Example 3

[0100] The difference between this comparative example and Example 1 is that no iron ore powder is added.

[0101] Result: The compressive strength of the product after graphitization is low, less than 2000N, the drum strength ID 13%, the reactivity CPI 22%.

[0102] Comparative Example 4

[0103] The difference between this comparative example and Example 1 is that cold pitch is used instead of high temperature pitch powder.

[0104] Result: The material mixing is not uniform, molding is difficult, and the structure of the product after carbonization is loose. This is because the use of cold pitch instead of high temperature pitch powder makes the material dispersion uneven. High temperature pitch powder is ground into powder, which facilitates uniform mixing of the material. However, the specific gravity of high temperature pitch powder is light, and it can disperse high temperature pitch in the material as much as possible under the action of high temperature water, which promotes the subsequent high temperature carbonization process.

[0105] The foregoing description of specific exemplary embodiments of the application has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application, and to thereby enable others skilled in the art to best utilize the application and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the application be defined by the claims and their equivalents.

Claims

1. A method for producing an iron-carbon composite charge, characterized by, The iron-carbon composite charge comprises the following raw materials by weight: Non-coking coal powder 61-84 parts; Iron oxide 10-30 parts; High-temperature accelerator 6-9 parts; Hot water 8-12 parts; The temperature of the hot water is ≥80℃; The high-temperature accelerator is high-temperature pitch powder and / or high-temperature coal tar; After the raw materials are uniformly mixed, the mixed materials are pelletized to obtain pellet materials; The pellet materials are carbonized at 650℃-1050℃; The carbonized pellet materials are directly water-cooled to obtain the iron-carbon composite charge; The metallic iron in the iron-carbon composite charge is solidly encapsulated by C.

2. The production method according to claim 1, characterized by, The non-coking coal powder is one or more of long flame coal, non-caking coal, and weakly caking coal.

3. The preparation method according to claim 1, characterized in that, The particle size of the non-coking coal powder is -200 mesh; And / or, the particle size of the iron oxide is -300 mesh; And / or, the particle size of the high-temperature accelerator is -200 mesh.

4. The production method according to claim 1, characterized by, The iron oxide includes one or more of iron oxide powder and iron ore powder.

5. The preparation method according to claim 1, characterized in that, The pressure of the pelletization is ≥500N.

6. The method of claim 1, wherein, The carbonization includes high-temperature carbonization or low-temperature carbonization; The carbonization temperature of the high-temperature carbonization is 850-1050℃, and the time is 2.5-4h; The carbonization temperature of the low-temperature carbonization is 650℃-850℃, and the time is 3.5-5h.

7. An iron-carbon composite charge, characterized by, The iron-carbon composite charge is prepared by the preparation method of any one of claims 1-6, The composition of the iron-carbon composite charge is as follows: C solid 42.0%-74.0%, TFe 6.5%-22.0%, ash content 10.5%-15.5%, wherein TFe is the total iron content; The drum strength of the iron-carbon composite charge is ≥75%, and the compressive strength is ≥3200N.

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