Method for reducing generation of hydrogen chloride in sintering flue gas

Abstract

The invention discloses a method for reducing generation of hydrogen chloride in sintering flue gas, which belongs to the technical field of sintering, and comprises the following steps: firstly, adding water into iron ore powder, A-type flux, solid fuel and return mine, mixing, granulating and processing into a sintering upper-layer mixture with proper moisture; adding water into iron ore powder, a B-type flux, an alkaline additive, a solid fuel and return mine, mixing, granulating and processing into a sintering lower-layer mixture with proper moisture; laying a grate-layer material on a sintering trolley, laying and sintering the lower-layer mixture on the grate-layer material to obtain a first cloth layer L1, and laying and sintering the upper-layer mixture on the first cloth layer L1 to obtain a second cloth layer L2; and finally igniting the second cloth layer L2 to start the sintering process. According to the sintering method, a double-layer material distribution mode is adopted, a strong alkali flux is adopted in a sintering lower-layer mixture, and an alkaline substance is added, so that hydrogen chloride generated in a material layer is neutralized and absorbed in the lower-layer material layer in the sintering process, and the purpose of reducing generation of hydrogen chloride is achieved.

Description

[0001] The invention relates to the technical field of sintering, and in particular to a method for reducing the generation of hydrogen chloride in sintering fume. Background Art

[0002] Sintered ore is the main iron-containing raw material for blast furnace ironmaking, and the stable operation of the sintering production line is an important factor in ensuring the supply of sintered ore. With the implementation of environmental protection policies, under the ultra-low emission policy of sintering flue gas, activated coke desulfurization and denitrification systems are widely used. During the operation of the sintering activated coke desulfurization and denitrification system, the hydrogen chloride contained in the sintering flue gas will react with ammonia in the ammonia injection area of ​​the activated coke system to form ammonium chloride. The accumulated ammonium chloride will cause blockage of the activated coke system and affect the permeability of the material layer. On the other hand, ammonium chloride adheres to the inner wall of the system, which will cause corrosion of the system and affect the operating life of the system. Under the ultra-low emission control standard of flue gas, the stable, efficient and smooth operation of the sintering desulfurization and denitrification system is the key to ensuring the stable production of the production line. At present, there is little relevant information specifically aimed at suppressing hydrogen chloride emissions from the source in response to the problem of hydrogen chloride in sintering flue gas. Summary of the invention

[0003] Technical problem to be solved: In view of the problems existing in the prior art, the present invention provides a method for reducing the generation of hydrogen chloride in sintering flue gas, thereby reducing the generation of hydrogen chloride in sintering flue gas, ensuring the stable operation of subsequent activated coke desulfurization and denitrification, and improving the production line operation rate and equipment service life.

[0004] Technical solution: A method for reducing the generation of hydrogen chloride in sintering flue gas according to the present invention comprises the following steps: Step 1: Add water to iron ore powder, Class A flux, solid fuel, and return ore, mix and granulate them into a sintering upper layer mixture with appropriate moisture content; Step 2: Mix iron ore powder, type B flux, alkaline additive, solid fuel, and returned ore with water and granulate them into a sintering lower layer mixture with appropriate moisture content; Step 3: Lay the base material on the sintering trolley, lay the sintering lower layer mixed material on the base material to obtain the first material layer L1, and then lay the sintering upper layer mixed material on the first material layer L1 to obtain the second material layer L2; Step 4: Ignite the second fabric layer L2 to start the sintering process.

[0005] Preferably, in step 1, the type A flux is one or a combination of serpentine, limestone and dolomite.

[0006] Preferably, in step 2, the type B flux is quicklime, slaked lime or a combination thereof.

[0007] Preferably, the sintered upper layer mixture and the sintered lower layer mixture use the same binary basicity and solid fuel ratio.

[0008] Preferably, the binary basicity is controlled at 1.5-3.0.

[0009] Preferably, the solid fuel ratio is controlled at 2.5-3.5%.

[0010] Preferably, in step 2, the alkaline additive is at most one of flake caustic soda, soda and baking soda.

[0011] Preferably, the amount of the alkaline additive used is 0-3% of the dry weight ratio of the sintering lower layer mixture.

[0012] Preferably, the thickness of the sintered upper mixed material is 700-900 mm, the thickness of the sintered lower mixed material is 100-200 mm, and the total thickness of the sintered material layer is controlled at 800-1100 mm.

[0013] The working principle of the present invention is as follows: According to the analysis and research, the sulfur dioxide gas released in the material layer during the sintering process reacts chemically with the soluble chloride salt in the lower water-containing material layer during the process of passing through the material layer to generate hydrogen chloride gas, which eventually enters the sintering flue gas. The chemical reaction formula can be expressed as follows: 2SO2+2H2O+4NaCl+O2=4HCl+2Na2SO4; According to the distribution and change law of sulfur dioxide in the sintering machine windbox recorded in relevant literature, sulfur dioxide is released less in the front part of sintering, and there is a phenomenon of concentrated release in the windbox at the end of sintering. This is because the sulfur dioxide generated in the upper part of the material layer will be absorbed by the water-containing material layer at the bottom of the material layer, so it is released less in the front windbox. As the sintering combustion layer moves downward, the water-containing layer at the bottom of the original material layer burns and releases sulfur dioxide in a concentrated manner, so the tail of the sintering machine occurs. Because the concentration of hydrogen chloride in the flue gas is low and cannot be accurately detected, and hydrogen chloride is highly soluble in water, according to the generation mechanism of hydrogen chloride and the release law of sulfur dioxide in the flue gas, the downward movement of hydrogen chloride generated in the upper material layer of sintering will also be absorbed by the lower water-containing material layer. By adding materials that can neutralize hydrogen chloride in the lower material layer of sintering, the amount of hydrogen chloride generated in the flue gas can be significantly reduced, that is, the problem of poor operation of the subsequent flue gas activated coke desulfurization and denitrification system caused by the presence of hydrogen chloride in the sintering flue gas can be solved, and the operation efficiency and service life of the activated coke desulfurization and denitrification system can be improved.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects: The sintering method of the present invention adopts a double-layer material distribution method, adopts a strong alkaline flux in the sintering lower layer mixed material, and adds alkaline substances, so that the hydrogen chloride generated in the material layer is neutralized and absorbed in the lower material layer during the sintering process, thereby achieving the purpose of reducing the generation of hydrogen chloride, solving the problem that the presence of hydrogen chloride in the flue gas causes the subsequent flue gas activated coke desulfurization and denitrification system to operate poorly, and improving the operating efficiency and service life of the activated coke desulfurization and denitrification system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a flowchart of the method for reducing the generation of hydrogen chloride in sintering flue gas. DETAILED DESCRIPTION

[0016] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the following will be combined with the attached Figure 1 The technical solutions of the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the described embodiments of the present invention belong to the scope of protection of the present invention.

[0017] Example 1: Figure 1 As shown, the present invention discloses a method for reducing the generation of hydrogen chloride in sintering flue gas, the method comprising the following steps: Step 1: Add water to iron ore powder, limestone flux, solid fuel, and return ore to mix and granulate into a sintering upper layer mixture with appropriate moisture content. The binary basicity of the sintering upper layer mixture is controlled at 2.0 and the solid fuel ratio is controlled at 3.0%. Binary basicity refers to the mass ratio of calcium oxide to silicon oxide in the raw materials.

[0018] Step 2: Add water to the iron ore powder, slaked lime flux, alkaline additive, solid fuel, and returned ore, mix and granulate them into a sintering lower layer mixture with appropriate moisture content. The alkaline additive is caustic soda flakes, and the amount of caustic soda flakes used accounts for 0.5% of the dry basis weight ratio of the sintering lower layer mixture; the binary alkalinity of the sintering upper layer mixture is controlled at 2.0, and the solid fuel ratio is controlled at 3.0%.

[0019] Step 3: Lay the base material on the sintering trolley, and lay the sintering lower layer mixed material on the base material to obtain the first material layer L1, and the thickness of L1 is 100mm; then lay the sintering upper layer mixed material on the first material layer L1 to obtain the second material layer L2, and the thickness of L2 is 800mm. The total thickness of the sintering material layer is controlled at 900mm.

[0020] Step 4: Ignite the second fabric layer L2 to start the sintering process.

[0021] Example 2: Figure 1 As shown, the present invention discloses a method for reducing the generation of hydrogen chloride in sintering flue gas, the method comprising the following steps: Step 1: Add water to iron ore powder, dolomite flux, solid fuel, and return ore to mix and granulate into a sintering upper layer mixture with appropriate moisture content. The binary basicity of the sintering upper layer mixture is controlled at 1.5, and the solid fuel ratio is controlled at 2.5%.

[0022] Step 2: Add water to iron ore powder, quicklime flux, alkaline additive, solid fuel, and returned ore, mix and granulate them into a sintering lower layer mixture with appropriate moisture content; the alkaline additive is soda, and the amount of soda accounts for 1.5% of the dry basis weight ratio of the sintering lower layer mixture; the binary alkalinity of the sintering upper layer mixture is controlled at 1.5, and the solid fuel ratio is controlled at 2.5%.

[0023] Step 3: Lay the base material on the sintering trolley, and lay the sintering lower layer mixed material on the base material to obtain the first material layer L1, and the thickness of L1 is 100mm; then lay the sintering upper layer mixed material on the first material layer L1 to obtain the second material layer L2, and the thickness of L2 is 700mm. The total thickness of the sintering material layer is controlled at 800mm.

[0024] Step 4: Ignite the second fabric layer L2 to start the sintering process.

[0025] Example 3: Figure 1 As shown, the present invention discloses a method for reducing the generation of hydrogen chloride in sintering flue gas, the method comprising the following steps: Step 1: Add water to iron ore powder, serpentine flux, solid fuel, and return ore, mix and granulate them into a sintering upper layer mixture with appropriate moisture content; the binary basicity of the sintering upper layer mixture is controlled at 2.5, and the solid fuel ratio is controlled at 3.5%.

[0026] Step 2: Add water to the iron ore powder, slaked lime flux, alkaline additive, solid fuel, and returned ore, mix and granulate them into a sintering lower layer mixture with appropriate moisture content; the alkaline additive is baking soda, and the amount of baking soda accounts for 2.5% of the dry basis weight ratio of the sintering lower layer mixture; the binary alkalinity of the sintering upper layer mixture is controlled at 2.5, and the solid fuel ratio is controlled at 3.5%.

[0027] Step 3: Lay the base material on the sintering trolley, and lay the sintering lower layer mixed material on the base material to obtain the first material layer L1, and the thickness of L1 is 200mm; then lay the sintering upper layer mixed material on the first material layer L1 to obtain the second material layer L2, and the thickness of L2 is 900mm. The total thickness of the sintering material layer is controlled at 1100mm.

[0028] Step 4: Ignite the second fabric layer L2 to start the sintering process.

[0029] Example 4: Figure 1 As shown, the present invention discloses a method for reducing the generation of hydrogen chloride in sintering flue gas, the method comprising the following steps: Step 1: Add water to iron ore powder, serpentine flux, solid fuel, and return ore, mix and granulate them into a sintering upper layer mixture with appropriate moisture content; the binary basicity of the sintering upper layer mixture is controlled at 3.0, and the solid fuel ratio is controlled at 3.5%.

[0030] Step 2: Add water to the iron ore powder, slaked lime flux, solid fuel, and returned ore to mix and granulate into a sintering lower layer mixture with appropriate moisture content; no alkaline additives are used; the binary alkalinity of the sintering upper layer mixture is controlled at 3.0, and the solid fuel ratio is controlled at 3.5%.

[0031] Step 3: Lay the base material on the sintering trolley, and lay the sintering lower layer mixed material on the base material to obtain the first material layer L1, and the thickness of L1 is 200mm; then lay the sintering upper layer mixed material on the first material layer L1 to obtain the second material layer L2, and the thickness of L2 is 800mm. The total thickness of the sintering material layer is controlled at 1000mm.

[0032] Step 4: Ignite the second fabric layer L2 to start the sintering process.

[0033] The production method of Examples 1 to 4 of the present invention is adopted, a double-layer material distribution method is adopted, a strong alkali flux is used in the sintering lower layer mixture, and an alkaline substance is added, so that the hydrogen chloride generated in the material layer is neutralized and absorbed in the lower material layer during the sintering process, thereby achieving the purpose of reducing the generation of hydrogen chloride, solving the problem that the presence of hydrogen chloride in the flue gas causes the subsequent flue gas activated coke desulfurization and denitrification system to operate poorly, improving the operating efficiency and service life activity of the activated coke desulfurization and denitrification system, and extending the frequency of cleaning ammonium chloride crystals in the activated coke desulfurization and denitrification system from the original one month / time to eight months / time, thereby greatly reducing the maintenance cost.

[0034] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for reducing the generation of hydrogen chloride in sintering flue gas, characterized in that: The following steps are involved: Step 1: Add water to iron ore powder, Class A flux, solid fuel, and return ore, mix and granulate them into a sintering upper layer mixture with appropriate moisture content; Step 2: Mix the iron ore powder, Class B flux, alkaline additive, solid fuel, and returned ore with water and granulate them into a sintering lower layer mixture with appropriate moisture content; Step 3: Lay the base material on the sintering trolley, lay the sintering lower layer mixed material on the base material to obtain the first material layer L1, and then lay the sintering upper layer mixed material on the first material layer L1 to obtain the second material layer L2; Step 4: Ignite the second fabric layer L2 to start the sintering process.

2. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 1, characterized in that: In step 1, the type A flux is one or a combination of serpentine, limestone and dolomite.

3. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 2, characterized in that: In step 2, the type B flux is quicklime, slaked lime or a combination thereof.

4. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 3, characterized in that: The sintered upper layer mixed material and the sintered lower layer mixed material adopt the same binary basicity and solid fuel ratio.

5. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 4, characterized in that: The binary basicity is controlled at 1.5-3.

0.

6. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 1, characterized in that: The solid fuel ratio is controlled at 2.5-3.5%.

7. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 1, characterized in that: In step 2, the alkaline additive is at most one of flake caustic soda, soda and baking soda.

8. The method for reducing the generation of hydrogen chloride in sintering flue gas according to claim 7, characterized in that: The amount of the alkaline additive used accounts for 0-3% of the dry weight of the sintering lower layer mixture.

9. The method for reducing the generation of hydrogen chloride in sintering flue gas according to any one of claims 1 to 8, characterized in that: The thickness of the upper sintering mixed material is 700-900 mm, the thickness of the lower sintering mixed material is 100-200 mm, and the total thickness of the sintering material layer is controlled at 800-1100 mm.

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