Method for forming a full cold material starting molten pool of an oxygen-enriched pulverized coal side-blown melting furnace

Abstract

The application discloses a full-cold-material starting-up molten pool forming method of an oxygen-enriched pulverized coal side-blown melting furnace, relates to the technical field of metallurgy, and comprises a furnace drying and temperature rising stage and a molten pool forming stage. The molten pool forming process comprises three stages of a first molten pool liquid level rising, a second molten pool liquid level rising and a third molten pool liquid level rising. On the basis of only adding water-quenched slag clinker of a fuming furnace and granular coal, the oxygen-enriched concentration ratio of pulverized coal and oxygen and the nitrogen dosage are adjusted to flexibly control the oxidation-reduction atmosphere in the furnace drying and molten pool forming furnace, the starting-up and cold-state molten pool forming process is shortened, hot-state slag with stable slag type is output for subsequent production of the molten pool of the side-blown melting furnace, the method is simple and operable, and the efficiency of starting-up and molten pool forming is improved.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and more specifically to a method for forming a molten pool in a side-blown oxygen-enriched pulverized coal furnace with all cold charge during start-up. Background Technology

[0002] Oxygen-enriched side-blown submerged combustion furnaces have been widely used in the processing of valuable materials such as lead, zinc, and silver from hydrometallurgical zinc slag, solid hazardous waste, and recycled lead. This type of furnace offers numerous advantages, including simple operation, low energy consumption, high recovery rate of valuable metals, and significant environmental benefits. Oxygen-enriched side-blown melting furnaces can be categorized into several types based on different heating methods, such as oxygen-enriched + natural gas, oxygen-enriched + anthracite granular coal, and oxygen-enriched + fuel oil. Among these, the oxygen-enriched pulverized coal side-blown melting furnace can use pulverized coal as both a heat source and a source of oxidation-reduction atmosphere within the furnace. This allows for better reduction and volatilization of valuable metals during melting, demonstrating significant advantages.

[0003] The currently reported start-up methods for this type of furnace mainly include: First, directly injecting hot molten slag into the side-blown furnace to form a molten pool. This method, which addresses the issue of providing hot molten slag in the previous process of the oxygen-enriched side-blown melting furnace, can be achieved directly by adjusting and optimizing the slag mix ratio beforehand. Second, when there is no hot molten slag process or upstream equipment, a method of forming a molten pool using solid raw and auxiliary fuels is employed. This involves layering and stacking coke, water-quenched slag, firewood, limestone, etc., inside the furnace, and gradually heating them with a spray gun until the materials inside the furnace melt to form a molten pool. However, there is currently a lack of research data and papers both domestically and internationally on the method of forming a molten pool with all cold materials in an oxygen-enriched side-blown melting furnace using an oxygen-enriched + pulverized coal supplementary heating system. Chinese invention patent announcement number CN104357650B discloses a rapid molten pool formation method for molten pool smelting, which involves using lump coal, fuel oil, and bottom material to form a molten pool through feeding, furnace drying, and molten pool formation steps. This method is not suitable for rapid molten pool formation with all cold materials in oxygen-enriched + pulverized coal side-blown molten pool furnaces. Chinese invention patent announcement number CN102417993B discloses a new method for starting up an oxygen-enriched side-blown molten pool furnace, which utilizes a method of starting up a furnace with hot slag from a settling and depleting electric furnace. This method is not suitable for starting up an oxygen-enriched + pulverized coal side-blown molten pool furnace with all cold materials and no hot molten slag in the front section. Chinese invention patent publication number CN101144121A discloses a solid start-up method for molten pool smelting, which suffers from problems such as a long start-up cycle, difficulty in controlling the molten pool formation process, and high slag viscosity. In summary, there is an urgent need to research a cold-material start-up method for oxygen-enriched pulverized coal side-blown molten pool furnaces that uses a single fuel, has low energy consumption, is easy to operate, and can be widely applied in the industry. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems by providing a method for forming a molten pool in a side-blown oxygen-enriched pulverized coal furnace with all cold feed, which has the characteristics of simpler fuel, lower energy consumption, easy operation, and can be widely used in the industry.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution: a method for forming a molten pool in a side-blown oxygen-enriched pulverized coal melting furnace with all cold charge during start-up, comprising the following steps:

[0006] Step 1, Furnace Heating Stage: Ignite 200-400 kg of firewood into the furnace, then gradually add 2-10 pulverized coal injection lances, with a pulverized coal flow rate of 200 kg / h-1000 kg / h and a pressure of 0.1-0.3 MPa; oxygen supply of 1200 Nm³.

[0007] / h-3200Nm3 / h, single-gun oxygen pressure 30KPa-100KPa; total nitrogen 100Nm3 / h-600Nm3 / h, single-gun nitrogen pressure 20KPa-60KPa, heat up to 600-700℃ and hold for 2-3 hours, heat up to 800-900℃ and hold for 2-3 hours, heat up to 1100-1350℃, furnace baking ends;

[0008] Step 2, Molten Pool Formation Stage:

[0009] 1) First rise of the molten pool level: The furnace temperature is 1100-1350℃. Coke, fuming furnace water-quenched slag clinker, and granular coal are added to the furnace. The total oxygen flow rate is 3000-3500 Nm3 / h, the pressure is 60-150 KPa, and the oxygen concentration is ≥80%. The amount of pulverized coal is 1000-1200 kg / h, and the pressure is maintained at 0.1-0.2 MPa. The total nitrogen flow rate is 400-600 Nm3 / h, and the pressure is maintained at 40-60 KPa. After 1-3 hours of melting, the molten pool level in the furnace rises by 200-400 mm.

[0010] 2) Secondary rise of molten pool level: The furnace temperature is 1100-1350℃. Water-quenched slag clinker and granular coal are added to the fuming furnace. The pulverized coal pressure is 0.2-0.4MPa and the pulverized coal quantity is 1200-1400kg / h. The oxygen concentration, oxygen quantity and nitrogen quantity pressure are kept constant. After 2-4 hours of melting, the molten pool level in the furnace rises to 400-600mm.

[0011] 3) The molten pool level rises three times: When the furnace temperature is 1100-1350℃ and the molten pool level is close to the height of the immersion spray gun, water-quenched slag clinker and granular coal from the fuming furnace are added; 0.4MPa compressed air is mixed in to reduce the oxygen concentration to 50-70%, with an oxygen flow rate of 3200-4500Nm3 / h and a pressure of 150-240KPa; nitrogen flow rate is 1000-1500Nm3 / h and a pressure of 60-150KPa; and pulverized coal quantity is 1400-1800kg / h. After 1-2 hours of melting, the molten pool level rises to 900-1100mm, the side-blown melting furnace molten pool is formed, and raw materials are added to switch to normal production control.

[0012] Preferably, the oxygen concentration must be maintained at ≥80% during the oven baking process in step one.

[0013] Preferably, the slag-forming composition of the water-quenched slag clinker in step two is: CaO: 7-11%, Zn: 1-4%, Pb: 0.01-0.03%, Fe: 34-38%, and SiO2: 23-27%.

[0014] Preferably, during the first rise of the molten pool level in step two, the amount of coke fed is 100-200 kg, the amount of water-quenched slag clinker fed is 2-5 t / h, and the amount of granular coal fed is 200-350 kg / h.

[0015] Preferably, during the second rise of the molten pool level in step two, the amount of water-quenched slag clinker fed into the fuming furnace is 6-9 t / h, and the amount of granular coal fed into the furnace is 350-500 kg / h.

[0016] Preferably, during the three rises of the molten pool level in step two, the amount of water-quenched slag clinker fed into the fuming furnace is 10-15 t / h, and the amount of granular coal fed into the furnace is 500-800 kg / h.

[0017] The beneficial effects of this invention are as follows: This invention achieves the formation of a fully cold-charged molten pool in an oxygen-enriched pulverized coal side-blown melting furnace. Based solely on the addition of water-quenched slag clinker from a fuming furnace and granular coal, the oxidation-reduction atmosphere within the furnace during furnace drying and molten pool formation is flexibly controlled through adjustments to the ratio of pulverized coal, oxygen, oxygen enrichment concentration, and nitrogen dosage. The entire process from furnace drying to molten pool formation takes approximately 5 hours, shortening the time required for furnace start-up and cold molten pool formation. It produces stable, hot slag for subsequent production in the side-blown melting furnace. This invention uses a single fuel type, has low energy consumption, is easy to operate, and can be widely applied in the industry for mature cold-charged pulverized coal side-blown melting furnace start-up. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0019] Example 1

[0020] A method for forming a molten pool during the start-up of a side-blown oxygen-enriched pulverized coal melting furnace with all cold feed includes the following steps:

[0021] (1) A 13㎡ oxygen-enriched pulverized coal side-blown melting furnace is adopted. The side-blown furnace is equipped with a total of 12 spray guns, of which 10 are used.

[0022] (2) Furnace heating stage. The total furnace heating time is 12 hours, and the temperature rises from room temperature to 1150℃. First, 300kg of firewood is put into the furnace for ignition. Oxygen and protective nitrogen are simultaneously injected through 10 spray guns. The amount of pulverized coal injected is gradually increased from two spray guns to 10 spray guns. The amount of pulverized coal increases from 300kg / h to 950kg / h, and the pressure is 0.15MPa; the total amount of oxygen increases from 1250Nm3 / h to 3000Nm3 / h, and the pressure gradually increases from 38KPa to 92KPa; the total amount of nitrogen increases from 116Nm3 / h to 580Nm3 / h, and the pressure gradually increases from 36KPa to 52KPa. During the furnace drying process, the oxygen concentration is maintained at 82-86%. Pulverized coal is gradually added, and the temperature rise curve is as follows: the temperature is raised to 680℃ and held for 1 hour, then gradually raised to 816℃ and held for 2 hours, and then gradually raised to 1150℃ and held until the furnace drying is completed.

[0023] (3) Molten Pool Formation Stage. When the furnace temperature is 1150℃, 160kg of coke and 2.5t / h of fuming furnace water-quenched slag clinker are first added to the furnace. The fuming furnace water-quenched slag clinker includes 9.21% CaO, 2.92% Zn, 0.02% Pb, 36.15% Fe, and 25.98% SiO2. 320kg / h of granulated coal, a total oxygen flow rate of 3120Nm3 / h, and an oxygen concentration maintained at 82-86%, 950kg / h of pulverized coal, and a pressure maintained at 0.15MPa, and a total nitrogen flow rate of 410Nm3 / h, and a pressure maintained at 45KPa, are added. After 2 hours of melting, the molten pool level in the furnace rises by 260mm. The water-quenched slag feed rate was increased to 6 t / h, granulated coal to 380 kg / h, pulverized coal pressure to 0.25 MPa, and pulverized coal quantity to 1250 kg / h. Oxygen concentration, oxygen quantity, nitrogen quantity, and pressure were maintained constant. After 2.5 hours of melting, the molten pool level in the furnace rose to 500 mm. When the molten pool level was close to submerging the spray gun, the water-quenched slag feed rate was increased to 11 t / h, granulated coal to 520 kg / h, and 0.4 MPa compressed air was mixed in, reducing the oxygen concentration to 56%. The oxygen enrichment flow rate was 3400 Nm³ / h, and the pressure was 162 kPa. The nitrogen flow rate was 1129 Nm³ / h.

[0024] At a pressure of 68 kPa and a pulverized coal rate of 1468 kg / h, after 1.8 hours of melting, the molten pool level rose to 980 mm. The molten pool in the side-blown melting furnace was formed, and raw materials could be added to resume normal production operations.

[0025] Example 2

[0026] A method for forming a molten pool during the start-up of a side-blown oxygen-enriched pulverized coal melting furnace with all cold feed includes the following steps:

[0027] (1) A 13㎡ oxygen-enriched pulverized coal side-blown melting furnace is adopted. The side-blown furnace is equipped with a total of 12 spray guns, of which 10 are used.

[0028] (2) Furnace heating stage. The total furnace heating time is 14 hours, and the temperature is raised from room temperature to 1200℃. First, 320kg of firewood is put into the furnace for ignition. Oxygen and protective nitrogen are simultaneously injected through 10 spray guns. The amount of pulverized coal injected is gradually increased from two spray guns to 10 spray guns. The amount of pulverized coal is increased from 250kg / h to 980kg / h, and the pressure is 0.2MPa; the total amount of oxygen is increased from 1300Nm3 / h to 3100Nm3 / h, and the pressure is gradually increased from 32KPa to 92KPa; the total amount of nitrogen is increased from 120Nm3 / h to 560Nm3 / h, and the pressure is gradually increased from 26KPa to 58KPa. During the furnace drying process, the oxygen concentration is maintained at 82-86%. Pulverized coal is gradually added, and the temperature rise curve is as follows: the temperature is raised to 650℃ and held for 1 hour, then gradually raised to 820℃ and held for 2 hours, and then gradually raised to 1200℃ and held until the furnace drying is completed.

[0029] (3) Molten Pool Formation Stage. At a furnace temperature of 1200℃, 150kg of coke and 3t / h of fuming furnace water-quenched slag clinker are first added to the furnace. The fuming furnace water-quenched slag clinker comprises 9.21% CaO, 2.92% Zn, 0.02% Pb, 36.15% Fe, and 25.98% SiO2. Particle coal is added at a rate of 350kg / h, total oxygen flow rate is 3300Nm3 / h with an oxygen enrichment concentration of 80-84%, pulverized coal quantity is 930kg / h, pressure is maintained at 0.15MPa, and total nitrogen flow rate is 450Nm3 / h with a pressure maintained at 50KPa. After 2 hours of melting, the molten pool level rises by 350mm. The flow rate of water-quenched slag was increased to 8 t / h, the flow rate of granulated coal was 420 kg / h, the pressure of pulverized coal was 0.35 MPa, and the flow rate of pulverized coal was 1320 kg / h. The oxygen concentration, oxygen quantity, nitrogen quantity, and pressure were kept constant. After 2 hours of melting, the molten pool level in the furnace rose to 550 mm. When the molten pool level was close to submerging the spray gun, the flow rate of water-quenched slag was increased to 12 t / h, the flow rate of granulated coal was 600 kg / h, and compressed air at 0.4 MPa was mixed in, reducing the oxygen concentration to 62%. The oxygen flow rate was 3600 Nm³ / h, and the pressure was 176 kPa. The nitrogen flow rate was 1250 Nm³ / h, the pressure was 78 kPa, and the pulverized coal flow rate was 1500 kg / h. After 1.5 hours of melting, the molten pool level rose to 1050 mm. The molten pool in the side-blown melting furnace was formed, and raw materials could be added to resume normal production operation.

[0030] Example 3

[0031] A method for forming a molten pool during the start-up of a side-blown oxygen-enriched pulverized coal melting furnace with all cold feed includes the following steps:

[0032] (1) A 13㎡ oxygen-enriched pulverized coal side-blown melting furnace is adopted. The side-blown furnace is equipped with a total of 12 spray guns, of which 10 are used.

[0033] (2) Furnace heating stage. The total furnace heating time is 16 hours, and the temperature is raised from room temperature to 1250℃. First, 300kg of firewood is put into the furnace for ignition. Oxygen and protective nitrogen are simultaneously injected through 10 spray guns. The amount of pulverized coal injected is gradually increased from two spray guns to 10 spray guns. The amount of pulverized coal is increased from 250kg / h to 1000kg / h, and the pressure is 0.25MPa; the total amount of oxygen is increased from 1250Nm3 / h to 2980Nm3 / h, and the pressure of a single gun is gradually increased from 40KPa to 86KPa; the total amount of nitrogen is increased from 135Nm3 / h to 580Nm3 / h, and the pressure of a single gun is gradually increased from 32KPa to 54KPa. During the furnace drying process, the oxygen concentration is maintained at 86-92%. Pulverized coal is gradually added, and the heating curve is as follows: the temperature is raised to 650℃ and held for 1 hour, then gradually raised to 800℃ and held for 2 hours, and then gradually raised to 1250℃ and held until the furnace drying is completed.

[0034] (3) Molten Pool Formation Stage. At a furnace temperature of 1250℃, 200kg of coke and 4t / h of fuming furnace water-quenched slag clinker are first added to the furnace. The fuming furnace water-quenched slag clinker comprises 9.21% CaO, 2.92% Zn, 0.02% Pb, 36.15% Fe, and 25.98% SiO2. Particle coal is added at a rate of 350kg / h, total oxygen flow rate is 3200Nm3 / h with an oxygen enrichment concentration of 90%, pulverized coal is added at a rate of 1100kg / h, and the pressure is maintained at 0.2MPa. Total nitrogen flow rate is 580Nm3 / h, and the pressure is maintained at 58KPa. After 2 hours of melting, the molten pool level in the furnace rises by 380mm. The flow rate of water-quenched slag was increased to 7 t / h, the flow rate of granulated coal was 480 kg / h, the pressure of pulverized coal was 0.35 MPa, and the flow rate of pulverized coal was 1300 kg / h. The oxygen concentration, oxygen quantity, nitrogen quantity, and pressure were kept constant. After 2 hours of melting, the molten pool level in the furnace rose to 580 mm. When the molten pool level was close to submerging the spray gun, the flow rate of water-quenched slag was increased to 14 t / h, the flow rate of granulated coal was 700 kg / h, and compressed air at 0.4 MPa was mixed in, reducing the oxygen concentration to 58%. The oxygen flow rate was 4200 Nm³ / h, and the pressure was 210 kPa. The nitrogen flow rate was 1360 Nm³ / h, the pressure was 82 kPa, and the pulverized coal flow rate was 1700 kg / h. After 1 hour of melting, the molten pool level rose to 1086 mm. The molten pool in the side-blown melting furnace was formed, and raw materials could be added to resume normal production operation.

[0035] This invention requires approximately 5 hours from furnace drying to the formation of the molten pool, shortening the overall furnace start-up time. It is simple, easy to operate, and improves labor efficiency.

[0036] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for forming a molten pool during the start-up of a side-blown oxygen-enriched pulverized coal melting furnace with all cold feed, characterized in that, Includes the following steps: Step 1, Furnace Heating Stage: Ignite 200-400 kg of firewood into the furnace, then gradually add 2-10 pulverized coal injection lances, with a pulverized coal flow rate of 200 kg / h-1000 kg / h and a pressure of 0.1-0.3 MPa; oxygen flow rate of 1200 Nm³ / h-3200 Nm³ / h, with a single lance oxygen pressure of 30 kPa-100 kPa; total nitrogen flow rate of 100 Nm³ / h-600 Nm³ / h, with a single lance nitrogen pressure of 20 kPa-60 kPa. Heat to 600-700℃ and hold for 2-3 hours, then heat to 800-900℃ and hold for 2-3 hours. Finally, heat to 1100-1350℃ to complete the furnace heating process. Step 2, Molten Pool Formation Stage: The molten pool level rises once: the furnace temperature is 1100-1350℃. Coke, fuming furnace water-quenched slag clinker, and granular coal are fed into the furnace. The amount of coke fed is 100-200kg, the amount of fuming furnace water-quenched slag clinker fed is 2-5t / h, and the amount of granular coal fed is 200-350kg / h. The total oxygen flow rate is 3000-3500Nm³ / h, the pressure is 60-150KPa, and the oxygen concentration is ≥80%. The amount of pulverized coal is 1000-1200kg / h, and the pressure is maintained at 0.1-0.2MPa. The total nitrogen flow rate is 400-600Nm³ / h, and the pressure is maintained at 40-60KPa. After 1-3 hours of melting, the molten pool level in the furnace rises by 200-400mm. Secondary rise of molten pool level: The furnace temperature is 1100-1350℃. Water-quenched slag clinker and granular coal are added to the fuming furnace. During the secondary rise of the molten pool level in step two, the amount of water-quenched slag clinker added to the fuming furnace is 6-9t / h, and the amount of granular coal added is 350-500kg / h; the pulverized coal pressure is 0.2-0.4MPa, the amount of pulverized coal is 1200-1400kg / h, and the oxygen concentration, oxygen quantity, nitrogen quantity, and pressure are kept constant. After 2-4 hours of melting, the molten pool level in the furnace rises to 400-600mm. The molten pool level rises in three stages: When the furnace temperature reaches 1100-1350℃ and the molten pool level is close to the height of the immersion spray gun, fuming furnace water-quenched slag clinker and granular coal are added. The amount of fuming furnace water-quenched slag clinker is 10-15t / h, and the amount of granular coal is 500-800kg / h. Compressed air at 0.4MPa is mixed in to reduce the oxygen concentration to 50-70%, with an oxygen flow rate of 3200-4500Nm³ / h and a pressure of 150-240KPa. Nitrogen flow rate is 1000-1500Nm³ / h, pressure is 60-150KPa, and pulverized coal is 1400-1800kg / h. After 1-2 hours of melting, the molten pool level rises to 900-1100mm, the side-blown melting furnace molten pool is formed, and raw materials are added to switch to normal production control.

2. The method for forming a fully cold charge molten pool in an oxygen-enriched pulverized coal side-blown melting furnace according to claim 1, characterized in that: In step one, the oxygen concentration must be maintained at ≥80% during oven baking.

3. The method for forming a molten pool in a side-blown oxygen-enriched pulverized coal melting furnace with all cold charge according to claim 1, characterized in that: The slag-forming composition of the water-quenched slag clinker in step two is as follows: CaO: 7-11%, Zn: 1-4%, Pb: 0.01-0.03%, Fe: 34-38%, SiO2: 23-27%.