Production method of solid fuel for sintering

Abstract

The invention relates to a production method of a solid fuel for sintering. The production method comprises the following steps: 1) screening activated carbon powder generated in a sintering flue gas desulfurization and denitrification process; 2) pretreating the active carbon powder raw material obtained in the step 1); (3) mixing the activated carbon fuel particles prepared in the step (2) with coke powder to obtain solid fuel; the activated carbon powder generated in the sintering flue gas desulfurization and denitrification process is pretreated and then serves as fuel to be supplied to a combustion system, more expensive coke powder can be partially replaced, the sintering production cost is greatly reduced, secondary reutilization of the activated carbon powder serving as waste in the past is achieved, and the production cost is reduced. By controlling the particle size of the sintered solid fuel prepared from the activated carbon powder, the consumption of the sintered solid fuel is reduced, and the goal of carbon emission reduction is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sintering, and in particular to a method for producing solid fuel for sintering. Background Art

[0002] Activated carbon has a large specific surface area and a suitable pore structure, so it has a strong selective adsorption capacity. In the field of flue gas purification, activated carbon can be used to remove sulfur dioxide and nitrogen oxides in flue gas. Among them, the unique adsorption properties of activated carbon can remove SO 2 Selectively adsorb SO 2 Under the combined action of water vapor and oxygen in the flue gas, it is oxidized to H 2 SO 4 , and are stored in the pores of activated carbon; at the same time, the activated carbon adsorption layer is equivalent to a high-efficiency filter layer. Under the action of collision and interception, most of the dust particles in the flue gas are captured in different parts of the bed layer, thus completing the flue gas desulfurization and dust removal purification process. 2 The H stored in the activated carbon after heating 2 SO 4 Reaction with C to generate SO 2 At the same time, the activated carbon is "activated and regenerated", that is, the adsorption performance is restored, so the activated carbon can be recycled. The denitrification rate can be as high as 60% to 70% by removing nitrogen oxides through catalytic reduction of activated carbon. In addition, activated carbon removes dioxins by adsorption, and the dioxin removal rate can reach more than 95%; it removes heavy metals by adsorption oxidation, and the heavy metal removal rate can reach more than 90%. Therefore, activated carbon is widely used in the flue gas desulfurization and denitrification process of sintering and pelletizing production.

[0003] Activated carbon has rich pore structure, large specific surface area and good adsorption performance, and can adsorb and catalyze the accumulation of other substances in the pores. The strong adsorption capacity of activated carbon pores is used to adsorb SO in flue gas. 2 , H 2 O, O 2 , SO in the activated carbon pores 2 , O2, H 2 O reacts to generate H 2 SO 4 ; When the flue gas temperature is in the range of 120~160℃, SO 2 The removal efficiency remains at a high level.

[0004] The activated carbon used in the CSCR desulfurization and denitrification system is cylindrical coal-based activated carbon particles with a diameter of about 9mm. During the production process, new activated carbon is added according to the drop in the material level of each adsorption module and the activated carbon buffer silo. The consumption of activated carbon in the system mainly consists of chemical consumption and physical consumption. Among them, physical consumption refers to the consumption caused by the activated carbon being discharged from the system in the form of activated carbon powder, fine particles, agglomerates, etc. after a period of use, when its particle size or other physical properties no longer meet the requirements of the desulfurization and denitrification system for recycling. Physical consumption occurs in every link of the activated carbon circulation process. Due to various mechanical forces such as collision, friction, and extrusion, the activated carbon particles are broken and worn, and the particles gradually become smaller. Finally, they are separated from the system through the wind screen, dust removal pipeline, and vibrating screen undersize.

[0005] The particle size of activated carbon is crucial. The particle size of activated carbon should not be too large or too small. If the particle size of activated carbon is too small, the resistance of flue gas passing through the bed will increase, reducing the amount of flue gas entering, thereby reducing the efficiency of desulfurization and denitrification; if the particle size of activated carbon is too large, the gaps between the particles will become larger, the resistance will become smaller, and the efficiency of desulfurization and denitrification will also be reduced. Summary of the invention

[0006] The present invention provides a method for producing solid fuel for sintering. The activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification is pretreated and then supplied to a combustion system as fuel, which can partially replace more expensive coke powder, greatly reducing the production cost of sintering, and realizing the secondary reuse of activated carbon powder that was previously waste. By controlling the particle size of the sintering solid fuel prepared from the activated carbon powder, the consumption of the sintering solid fuel is reduced, which is conducive to achieving the goal of carbon emission reduction.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for producing solid fuel for sintering, comprising the following steps:

[0009] 1) Screening the activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification to obtain an activated carbon powder raw material with a particle size of less than 1.5 mm;

[0010] 2) Pre-treating the activated carbon powder raw material obtained in step 1); specifically, mixing 95% to 98% of activated carbon powder, 0.2% to 0.6% of water glass, 0.5% to 0.8% of bentonite and 1.0% to 4.0% of quicklime by weight; then spraying a saturated quicklime solution on the mixed material to obtain a mixture, wherein the water content of the mixture is 5% to 8% by weight; allowing the mixture to stand for 20 to 30 minutes, and then pressing it into agglomerates and drying it; crushing the dried agglomerates to obtain activated carbon fuel particles, wherein the particle size composition of the activated carbon fuel particles is as follows by mass percentage: particles larger than 3 mm account for 5% to 10%, particles 1 to 3 mm account for 75% to 90%, and particles smaller than 1 mm account for the remainder;

[0011] 3) The activated carbon fuel particles prepared in step 2) are mixed with coke powder to obtain a solid fuel, and the mixing ratio by weight percentage is activated carbon fuel particles: 45% to 75%, coke powder: 25% to 55%.

[0012] In the step 1), the industrial analysis components of the activated carbon powder are fixed carbon: 72% to 76%, ash: 12% to 15%, and volatile matter: 12% to 14% by mass percentage.

[0013] In the step 2), the mixing time is 5 to 10 minutes, of which the first 2 to 5 minutes are dry mixing, and after the dry mixing is completed, a mist of saturated quicklime solution is sprayed into the powerful mixer.

[0014] In the step 2), the pressed agglomerates are dried at a temperature of 80 to 100° C. for 8 to 10 hours.

[0015] The agglomerate is a rectangular parallelepiped, with length×width×height=30mm×30mm×20mm~30mm×30mm×45mm; the pressure when pressing the agglomerate is 5~30MPa.

[0016] In the step 2), the chemical composition of bentonite is SiO 2 :48%~65%,Al 2 O 3 : 11% ~ 17%, CaO: 2.0% ~ 5.0%, MgO: 1.0% ~ 5.5%, and the remainder are impurity elements.

[0017] In step 2), the chemical composition of quicklime is CaO: 82% to 87%, SiO 2 :2.5%~4.0%, MgO: 3%~5%, Al 2 O 3 : 0.5% to 1.5%, the remainder being impurity elements.

[0018] The quicklime has a particle size of less than 0.074 mm and an activity of more than 300 ml.

[0019] In the step 3), the industrial analysis components of the coke powder are as follows by mass percentage: fixed carbon: 83% to 86%, ash: 13% to 15%, and volatile matter: 1% to 3%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification is used as solid fuel for sintering production after pretreatment, replacing the more expensive coke powder, greatly reducing the sintering production cost; in the conventional production process, the activated carbon powder belongs to the waste generated in the process of desulfurization and denitrification. The present invention realizes the secondary reuse of the activated carbon powder, achieving the purpose of fully utilizing the material resources inside the sintering system.

[0022] 2) During the pretreatment of activated carbon powder, sulfur is fixed in the sintered ore by adding quicklime and spraying quicklime digestion liquid; compared with the method of directly using activated carbon powder as fuel for sintering production, it overcomes the problem of high sulfur content in activated carbon powder that plays an adsorption role in the flue gas desulfurization and denitrification process, which in turn leads to high sulfur dioxide emissions during the sintering process, and alleviates the load of the flue gas desulfurization system.

[0023] 3) During the pretreatment of activated carbon powder, a saturated solution of quicklime is sprayed. After being pressed into agglomerates, the activated carbon powder wraps the alkaline flux. When used as a sintering fuel, it can not only reduce the amount of external alkaline flux, but also solidify sulfur in the sintered ore, ultimately reducing the SO in the sintering flue gas. 2 emissions, achieving the goal of emission reduction.

[0024] 4) After the pretreated activated carbon powder is pressed into balls, it is crushed to the set particle size composition, which indirectly optimizes the particle size composition of the sintering fuel and directly reduces the consumption of sintering solid fuel, which has a positive effect on reducing carbon dioxide emissions and helps steel companies achieve their carbon emission reduction goals. DETAILED DESCRIPTION

[0025] The method for producing a solid fuel for sintering according to the present invention comprises the following steps:

[0026] 1) Screening the activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification to obtain an activated carbon powder raw material with a particle size of less than 1.5 mm;

[0027] 2) Pre-treating the activated carbon powder raw material obtained in step 1); specifically, mixing 95% to 98% of activated carbon powder, 0.2% to 0.6% of water glass, 0.5% to 0.8% of bentonite and 1.0% to 4.0% of quicklime by weight; then spraying a saturated quicklime solution on the mixed material to obtain a mixture, wherein the water content of the mixture is 5% to 8% by weight; allowing the mixture to stand for 20 to 30 minutes, and then pressing it into agglomerates and drying it; crushing the dried agglomerates to obtain activated carbon fuel particles, wherein the particle size composition of the activated carbon fuel particles is as follows by mass percentage: particles larger than 3 mm account for 5% to 10%, particles 1 to 3 mm account for 75% to 90%, and particles smaller than 1 mm account for the remainder;

[0028] 3) The activated carbon fuel particles prepared in step 2) are mixed with coke powder to obtain a solid fuel, and the mixing ratio by weight percentage is activated carbon fuel particles: 45% to 75%, coke powder: 25% to 55%.

[0029] In the step 1), the industrial analysis components of the activated carbon powder are fixed carbon: 72% to 76%, ash: 12% to 15%, and volatile matter: 12% to 14% by mass percentage.

[0030] In the step 2), the mixing time is 5 to 10 minutes, of which the first 2 to 5 minutes are dry mixing, and after the dry mixing is completed, a mist of saturated quicklime solution is sprayed into the powerful mixer.

[0031] In the step 2), the pressed agglomerates are dried at a temperature of 80 to 100° C. for 8 to 10 hours.

[0032] The agglomerate is a rectangular parallelepiped, with length×width×height=30mm×30mm×20mm~30mm×30mm×45mm; the pressure when pressing the agglomerate is 5~30MPa.

[0033] In the step 2), the chemical composition of bentonite is SiO 2 :48%~65%,Al 2 O 3 : 11% ~ 17%, CaO: 2.0% ~ 5.0%, MgO: 1.0% ~ 5.5%, and the remainder are impurity elements.

[0034] In step 2), the chemical composition of quicklime is CaO: 82% to 87%, SiO 2 :2.5%~4.0%, MgO: 3%~5%, Al 2 O 3 : 0.5% to 1.5%, the remainder being impurity elements.

[0035] The quicklime has a particle size of less than 0.074 mm and an activity of more than 300 ml.

[0036] In the step 3), the industrial analysis components of the coke powder are as follows by mass percentage: fixed carbon: 83% to 86%, ash: 13% to 15%, and volatile matter: 1% to 3%.

[0037] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with examples. The following examples are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention.

[0038] [Example 1]

[0039] In this embodiment, the production process of sintering solid fuel is as follows:

[0040] 1. Take the activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification. The industrial analysis composition of the activated carbon powder is fixed carbon: 72%, ash: 15%, volatile matter: 13% by mass percentage; screen the activated carbon powder and take particles with a particle size of less than 1.5 mm as the raw material of activated carbon powder.

[0041] 2. Pre-treat the activated carbon powder raw materials that have completed screening;

[0042] Take activated carbon powder raw materials, water glass, bentonite, and quicklime for pretreatment; the chemical composition (mass percentage) of bentonite is: SiO 2 60%,Al 2 O 3 15%, CaO 3.0%, MgO 3.5%, and the remainder is impurity elements. The chemical composition (mass percentage) of quicklime is: CaO 82%, SiO 2 3.0%, MgO 4%, Al 2 O 3 1.0%, the remainder is impurity elements. The particle size composition of quicklime is less than 0.074mm, with a mass percentage of 100%, and the activity of quicklime is 310ml.

[0043] By weight percentage, 96% of activated carbon powder raw materials, 0.4% of water glass, 0.7% of bentonite and 2.9% of quicklime are mixed in a powerful mixer for 8 minutes. The first 3 minutes of the mixing process are dry mixing. In the last 5 minutes of the mixing process, a mist of quicklime saturated solution is sprayed into the powerful mixer. The spraying amount of the quicklime saturated solution is controlled so that the moisture content of the final mixture is 6.5% of the total amount of the mixture by weight percentage. The mixed mixture is allowed to stand for 20 minutes and then transported to a briquetting machine to be pressed into agglomerates. The pressed agglomerates are rectangular parallelepipeds with a length × width × height = 30mm × 30mm × 20mm. The pressure of the briquetting machine when pressing the pellets is 5MPa. The pressed agglomerates are dried at 80°C for 10 hours.

[0044] The dried agglomerates are crushed in a single-tooth roller crusher to obtain activated carbon fuel particles, whose particle size composition is as follows by mass percentage: particles larger than 3 mm account for 10%, particles between 1 and 3 mm account for 75%, and particles smaller than 1 mm account for 15%.

[0045] 3. Take the coke powder for sintering production, whose industrial analysis composition (mass percentage) is: fixed carbon 83%, ash 14%, volatile matter 3%. Mix the pre-treated activated carbon fuel particles and coke powder in a weight percentage of 45%:55%, and add them into the sintering combustion system as solid fuel.

[0046] Compared with the sintering production process that uses coke powder as solid fuel, after the application of this embodiment, the coke powder consumption in the sintering process is reduced from 50kg / t to 36kg / t, a decrease of 14kg / t, a decrease of nearly 28 percentage points; the drum strength of the sintered ore is increased from 81.0% to 89.6%, an increase of 8.6 percentage points.

[0047] [Example 2]

[0048] In this embodiment, the production process of sintering solid fuel is as follows:

[0049] 1. Take the activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification. The industrial analysis composition of the activated carbon powder is fixed carbon: 76%, ash: 12%, and volatile matter: 12% by mass percentage; screen the activated carbon powder and take particles with a particle size of less than 1.5 mm as the raw material of activated carbon powder.

[0050] 2. Pre-treat the activated carbon powder raw materials that have completed screening;

[0051] Take activated carbon powder raw materials, water glass, bentonite, and quicklime for pretreatment; the chemical composition (mass percentage) of bentonite is: SiO 2 55%,Al 2 O 313%, CaO 5.0%, MgO 5.5%, and the remainder is impurity elements. The chemical composition (mass percentage) of quicklime is: CaO 87%, SiO 2 2.5%, MgO 3.0%, Al 2 O 3 0.5%, the remainder is impurity elements. The particle size composition of quicklime is less than 0.074mm, with a mass percentage of 100%, and the activity of quicklime is 330ml.

[0052] By weight percentage, 98% of activated carbon powder raw materials, 0.5% of water glass, 0.5% of bentonite and 1.0% of quicklime are mixed in a powerful mixer for 10 minutes. The first 5 minutes of the mixing process are dry mixing. In the last 5 minutes of the mixing process, a mist of quicklime saturated solution is sprayed into the powerful mixer. The spraying amount of the quicklime saturated solution is controlled so that the moisture content of the final mixture is 8% of the total amount of the mixture by weight percentage. The mixed mixture is allowed to stand for 30 minutes and then transported to a briquetting machine to be pressed into agglomerates. The pressed agglomerates are rectangular parallelepipeds with length × width × height = 30mm × 30mm × 45mm. The pressure of the briquetting machine when pressing the pellets is 30MPa. The pressed agglomerates are dried at 100°C for 8 hours.

[0053] The dried agglomerates are crushed in a single-tooth roller crusher to obtain activated carbon fuel particles, the particle size composition of which is as follows by mass percentage: particles larger than 3 mm account for 5%, particles between 1 and 3 mm account for 90%, and particles smaller than 1 mm account for 5%.

[0054] 3. Take the coke powder for sintering production, whose industrial analysis composition (mass percentage) is: fixed carbon 86%, ash 13%, volatile matter 1%. Mix the pre-treated activated carbon fuel particles and coke powder in a weight percentage of 75%:25% and add them into the sintering combustion system as solid fuel.

[0055] Compared with the sintering production process that uses coke powder as solid fuel, after the application of this embodiment, the coke powder consumption in the sintering process is reduced from 50kg / t to 32kg / t, a decrease of 18kg / t, a decrease of nearly 36 percentage points; the drum strength of the sintered ore is increased from 81.0% to 92.1%, an increase of 11.1 percentage points.

[0056] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for producing solid fuel for sintering, characterized in that: The steps include: 1) Screening the activated carbon powder produced in the process of sintering flue gas desulfurization and denitrification to obtain an activated carbon powder raw material with a particle size of less than 1.5 mm; 2) Pre-treating the activated carbon powder raw material obtained in step 1); specifically, mixing 95% to 98% of activated carbon powder, 0.2% to 0.6% of water glass, 0.5% to 0.8% of bentonite and 1.0% to 4.0% of quicklime by weight; then spraying a saturated quicklime solution on the mixed material to obtain a mixture, wherein the water content of the mixture is 5% to 8% by weight; allowing the mixture to stand for 20 to 30 minutes, and then pressing it into agglomerates and drying it; crushing the dried agglomerates to obtain activated carbon fuel particles, wherein the particle size composition of the activated carbon fuel particles is as follows by mass percentage: particles larger than 3 mm account for 5% to 10%, particles 1 to 3 mm account for 75% to 90%, and particles smaller than 1 mm account for the remainder; 3) The activated carbon fuel particles prepared in step 2) are mixed with coke powder to obtain a solid fuel, and the mixing ratio by weight percentage is activated carbon fuel particles: 45% to 75%, coke powder: 25% to 55%.

2. The method for producing a solid fuel for sintering according to claim 1, characterized in that: In the step 1), the industrial analysis components of the activated carbon powder are fixed carbon: 72% to 76%, ash: 12% to 15%, and volatile matter: 12% to 14% by mass percentage.

3. The method for producing a solid fuel for sintering according to claim 1, characterized in that: In the step 2), the mixing time is 5 to 10 minutes, of which the first 2 to 5 minutes are dry mixing, and after the dry mixing is completed, a mist of saturated quicklime solution is sprayed into the powerful mixer.

4. The method for producing a solid fuel for sintering according to claim 1, characterized in that: In the step 2), the pressed agglomerates are dried at a temperature of 80 to 100° C. for 8 to 10 hours.

5. The method for producing a solid fuel for sintering according to claim 1 or 4, characterized in that: The agglomerate is a rectangular parallelepiped, with length×width×height=30mm×30mm×20mm~30mm×30mm×45mm; the pressure when pressing the agglomerate is 5~30MPa.

6. The method for producing a solid fuel for sintering according to claim 1, characterized in that: In the step 2), the chemical composition of the bentonite is SiO2: 48% to 65%, Al2O3: 11% to 17%, CaO: 2.0% to 5.0%, MgO: 1.0% to 5.5%, and the remainder is impurity elements.

7. The method for producing a solid fuel for sintering according to claim 1, characterized in that: In the step 2), the chemical composition of quicklime is CaO: 82% to 87%, SiO2: 2.5% to 4.0%, MgO: 3% to 5%, Al2O3: 0.5% to 1.5%, and the remainder is impurity elements.

8. The method for producing a solid fuel for sintering according to claim 1 or 7, characterized in that: The quicklime has a particle size of less than 0.074 mm and an activity of more than 300 ml.

9. The method for producing a solid fuel for sintering according to claim 1, characterized in that: In the step 3), the industrial analysis components of the coke powder are as follows by mass percentage: fixed carbon: 83% to 86%, ash: 13% to 15%, and volatile matter: 1% to 3%.