A blast furnace smelting method using ultra-high lump ore ratio

Abstract

The present invention discloses a blast furnace smelting method using an ultra-high lump ore ratio, comprising the following steps: (1) raw material control: controlling the mass percentage of lump ore in the raw material to be 35% to 40%, the remainder being sintered ore, and selectively controlling the quality of the lump ore and the sintered ore; (2) charging system: gradually reducing the ore belt, and gradually adopting a charging system of loosening the edge and guiding the center two airflows; (3) air supply system: reducing the tuyere area, and controlling the actual wind speed and the actual blast kinetic energy; (4) oxygen enrichment balance system: reducing the blast oxygen enrichment, maintaining a suitable theoretical combustion temperature, and transferring the reduced blast oxygen enrichment to the hot blast furnace for oxygen-enriched furnace burning operation; (5) slag iron smelting system: controlling the ratio of silicon to sulfur in molten iron, and controlling the basicity and magnesium-aluminum ratio of the slag. The advantages of the present invention are that the adverse effects of high-proportion lump ore production on the blast furnace can be efficiently and accurately adjusted, ensuring stable operation of the furnace condition in high-proportion lump ore production, thereby reducing the cost per ton of iron.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a blast furnace smelting method using an ultra-high lump ore ratio. Background Art

[0002] In order to achieve the goal of environmental protection, high quality, low consumption, high efficiency and innovation in ironmaking production, a new raw material structure framework is opened up to cooperate with the ironmaking process to tap the potential for cost reduction. Under the premise of the obvious price difference between pellets and lump ore, it is decided to break the inherent raw material ratio structure, increase the lump ore ratio and gradually cancel the pellet ratio for smelting in the furnace. In production, the blast furnace needs to increase the proportion of lump ore to replace artificial rich ore, especially high-priced pellet ore, to reduce the cost of ironmaking. At the same time, the proportion of lump ore used in blast furnace smelting is increased, which correspondingly reduces the proportion of other raw materials, further reduces the processing steps of other raw materials, and then improves resource utilization, achieving the purpose of energy conservation and emission reduction.

[0003] The existing defects and deficiencies are as follows: (1) There are few precedents for blast furnace smelting production with a high ratio of lump ore of more than 35% in the industry. There is insufficient production experience, and the cost of producing a ton of iron is unclear. After the lump ore ratio is increased, the output and consumption will change, and how to balance them? The proportion of lump ore used in daily production is only about 16%. (2) After the lump ore ratio is increased, the softening and melting temperatures of the lump ore are lower than those of pellet ore and sintered ore, and the soft melting temperature range is wide. After the lump ore ratio is increased, the soft melting zone of the blast furnace becomes wider and moves upward, and the volume of the wet area with poor permeability increases. In addition, the lump ore explodes and pulverizes in the low temperature zone of the blast furnace, further deteriorating the permeability of the blast furnace, and the operation of the blast furnace will be threatened. Summary of the invention

[0004] The purpose of the present invention is to provide a blast furnace smelting method using an ultra-high lump ore ratio, to efficiently and accurately adjust a series of adverse effects on the blast furnace brought about by the high-ratio lump ore production, to ensure stable operation of the furnace condition during the high-ratio lump ore production, to achieve the new goal of reducing the cost per ton of iron, to create greater economic benefits for the company, and to point out the direction and set a new benchmark for the charge structure of the blast furnace ironmaking industry.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A blast furnace smelting method using an ultra-high lump ore ratio, characterized in that it comprises the following steps:

[0007] (1) Raw material control: The mass percentage of lump ore in the raw material is controlled to be 35% to 40%, and the rest is sintered ore. The quality of lump ore and sintered ore in the raw material is selectively controlled. All fuel coke is dry quenched, and the moisture content of dry quenched coke is controlled to be no higher than 1.5%;

[0008] (2) Loading system: gradually reduce the ore belt, gradually adopt a loading system that loosens the edge and guides the center airflow, and adjust the order of distribution;

[0009] (3) Air supply system: reduce the air outlet area by 3% to 5% and ensure that the actual wind speed is not less than 240m / s and the actual kinetic energy of the air is not less than 62KJ / S;

[0010] (4) Oxygen enrichment balance system: reduce the oxygen enrichment of the blast air, maintain the appropriate theoretical combustion temperature of 2280℃~2300℃, and transfer the reduced oxygen enrichment of the blast air to the hot blast furnace for oxygen-enriched combustion operation, and adjust the air temperature in the hot blast furnace accordingly;

[0011] (5) Slag iron smelting system: Control the ratio of silicon to sulfur in molten iron, the molten iron temperature is not less than 1490℃, the basicity of slag is 1.25±0.03, and the magnesium-aluminum ratio of slag is controlled, and the slag temperature is not less than 1520℃.

[0012] Preferably, the basicity R2 of the sintered ore in (1) is 1.95±0.05, the grade is not less than 54.5%, and the slag-iron ratio is controlled to be ≤310kg / t.

[0013] Preferably, the moisture content of the raw material lump ore in (1) is not higher than 5%, the loss on burn is not higher than 8%, and the powder content of the lump ore raw material entering the furnace <5mm does not exceed 5%, and 5mm-10mm does not exceed 25%.

[0014] Preferably, before the lump ore in (1) is fed to the blast furnace trough, it is pre-screened using a vibrating screen with a screen tooth gap of 8 mm to reduce the powder content of the lump ore in advance, and a drying system is used to further reduce the moisture content of the lump ore. The frequency of cleaning the lump ore is increased, the vibrating screen is vibrated in advance, and the feeding speed is subsequently controlled.

[0015] Preferably, the feeding speed control is as follows: the overall feeding speed of ore raw materials is not more than 13kg / s, the feeding speed of fuel coke is not more than 10kg / s, and when the screening particle size under the trough does not meet the requirements, the screening speed should be controlled by timely adjusting the movable gate.

[0016] Preferably, the raw material for the blast furnace in (2) is made of C3 38.5 3 36 2 33 2 30 2 26 O3 37.5 3 34.5 2 31.5 2 28.5 Adjusted to C4 38 3 35.5 2 32.5 2 29.5 2 26.5 O2 35.5 333.5 3 31 2 28.5 The angle difference was adjusted from 0.62 to -1.68, the ore belt was reduced from 9° to 6°, and the order of distribution was adjusted at the same time. The block ore was kept away from the edge as much as possible, and the block ore was distributed in the middle ore belt with small coke pieces in the ore belt.

[0017] Preferably, the oxygen enrichment of the blast in (4) is reduced to 6000m 3 / min, the air temperature in the hot blast furnace is controlled between 1210℃ and 1240℃.

[0018] Preferably, in said (5), the silicon content in the molten iron is 0.3% to 0.5%, the sulfur content is 0.02% to 0.04%, and the magnesium-aluminum ratio of the slag is not less than 0.60%.

[0019] In summary, the present invention has the following beneficial effects:

[0020] 1. The present invention reduces the amount of clinker used by increasing the lump ore ratio and eliminating the pellet ratio for furnace smelting, thereby reducing the ironmaking cost, thereby improving resource utilization and achieving the purpose of energy conservation and emission reduction.

[0021] 2. The present invention optimizes and controls the raw materials, charging system, air supply system, oxygen enrichment balance system and slag iron smelting system, thereby improving the qualified rate and stability of iron products under high proportion of lump ore. DETAILED DESCRIPTION

[0022] The specific implementation modes of the present invention are further described below, and these embodiments do not constitute a limitation of the present invention.

[0023] A blast furnace smelting method using an ultra-high lump ore ratio comprises the following steps:

[0024] (1) Raw material control: The mass percentage of lump ore in the raw material is controlled to be 35% to 40%, and the remainder is sintered ore. The quality of lump ore and sintered ore in the raw material is selectively controlled. The basicity R2 of the sintered ore is 1.95±0.05. The basicity R2 of the sintered ore is stabilized to stabilize the slag system, stabilize the soft melting zone, and ensure the operation of the furnace. The grade is not less than 54.5%. If the grade is too low, the amount of molten iron produced is small, resulting in low smelting efficiency. A grade higher than 54.5% ensures the smelting efficiency of the blast furnace and reduces the smelting cost. The slag-iron ratio is controlled to be ≤310kg / t. The slag-iron ratio refers to the ratio of the smelted slag to the molten iron. The slag-iron ratio is ≤310kg / t, which also ensures the smelting efficiency of the blast furnace and reduces the smelting cost. The moisture content of the raw material lump ore is not higher than 5%, ensuring that the lump ore is as dry as possible, improving the screening effect before entering the furnace, and the burnout is not higher than 8%, reducing the burnout in the ore furnace, ensuring The effective weight of lump ore entering the furnace is verified to reduce waste. The powder content of lump ore raw materials entering the furnace is less than 5mm and does not exceed 5%, and 5mm-10mm does not exceed 25%. The internal air permeability of the blast furnace is improved to ensure stable operation of the furnace. Before the lump ore is fed to the blast furnace trough, it is pre-screened with a vibrating screen with a screen tooth gap of 8mm to reduce the powder content of the lump ore in advance. The drying system is used to further reduce the moisture content of the lump ore, and the frequency of lump ore cleaning is increased. The vibrating screen is vibrated in advance to reduce the powder content of the ore entering the furnace, improve the particle size, and improve the air permeability of the blast furnace. Subsequently, the feeding speed is controlled. The feeding speed control is as follows: the overall feeding speed of the ore raw materials is not more than 13kg / s, and the feeding speed of the fuel coke is not more than 10kg / s. When the screening particle size under the trough does not meet the requirements, the screening speed should be controlled by timely adjusting the movable gate to reduce the powder entering the furnace as much as possible while ensuring the feeding speed to improve the air permeability of the material column. All fuel coke is dry quenched, and the moisture content of the dry quenched coke is controlled to be no higher than 1.5%. While ensuring the feeding speed, the powder entering the furnace is minimized to improve the permeability of the material column.

[0025] (2) Charging system: gradually reduce the ore belt, gradually adopt the charging system of loosening the edge and guiding the center airflow, and adjust the charging sequence. The charging system of blast furnace raw fuel is changed from C3 38.5 3 36 2 33 2 30 2 26 O3 37.5 3 34.5 2 31.5 2 28.5 Adjusted to C4 38 3 35.5 2 32.5 2 29.5 2 26.5 O2 35.5 3 33.5 3 31 2 28.5The angle difference was adjusted from 0.62 to -1.68, and the ore belt was reduced from 9° to 6° to improve the gas distribution after the lump ore was increased in proportion, thereby improving the permeability of the material column and ensuring the operation of the furnace. At the same time, the order of distribution was adjusted, and the lump ore was kept away from the edge as much as possible and distributed in the middle ore belt with small coke pieces in the ore belt to reduce the adverse effects of lump ore explosion, thereby improving the adverse factors of poor permeability, improving the permeability of the material column and ensuring stable operation of the furnace.

[0026] (3) Air supply system: Reduce the air outlet area by 3% to 5% compared with the normal level, and ensure that the actual wind speed is not less than 240m / s and the actual kinetic energy of the air is not less than 62KJ / S, so as to achieve the purpose of developing the central airflow and stabilizing the edge airflow.

[0027] (4) Oxygen enrichment balance system: reduce the oxygen enrichment of the blast to 6000m 3 / min, appropriately reduce the oxygen enrichment, control the smelting intensity, improve the blast furnace's ability to resist fluctuations, maintain a suitable theoretical combustion temperature of 2280℃ ~ 2300℃, ensure the active combustion zone in the tuyere, stabilize the smelting process, and transfer the reduced blast oxygen enrichment to the hot blast stove for oxygen-enriched burning operation, so as to increase the wind temperature and reduce the blast furnace fuel consumption, so as to ensure better technical and economic indicators, use the hot blast stove at its maximum capacity, and control the wind temperature in the hot blast stove between 1210℃ ~ 1240℃.

[0028] Slag iron smelting system: control the silicon ratio in the molten iron to 0.3%~0.5%, and the sulfur ratio to 0.02%~0.04%, to ensure the output of qualified molten iron. The molten iron temperature is not lower than 1490℃, to ensure that the blast furnace has sufficient heat, to maintain the furnace activity, to ensure stable smelting operation, the basicity of the slag is 1.25±0.03, and the magnesium-aluminum ratio of the slag is controlled to be not lower than 0.60%, to stabilize the slag basicity and magnesium-aluminum ratio, thereby stabilizing the slag system, ensuring the slag temperature, improving the slag fluidity, ensuring the slag desulfurization effect, smelting molten iron with qualified ingredients, stabilizing the furnace condition, and the slag temperature is not lower than 1520℃. The higher slag temperature can purify the molten iron composition, ensure the slag iron fluidity, and allow the molten iron to flow smoothly out of the furnace.

[0029] Example 1

[0030] The mass percentage of lump ore in the raw materials is 35%, and the rest is sintered ore. Subsequently, the above raw materials, charging system, air supply system, oxygen enrichment balance system and slag iron smelting system are used for optimization and control, and iron tapping is completed to produce qualified pig iron and by-products (slag, dust, coal gas).

[0031] Example 2

[0032] The mass percentage of lump ore in the raw materials is 37%, and the rest is sintered ore. Subsequently, the above raw materials, charging system, air supply system, oxygen enrichment balance system and slag iron smelting system are used for optimization and control, and iron tapping is completed to produce qualified pig iron and by-products (slag, dust, and coal gas).

[0033] Example 3

[0034] The mass percentage of lump ore in the raw materials is 40%, and the rest is sintered ore. Subsequently, the above raw materials, charging system, air supply system, oxygen enrichment balance system and slag iron smelting system are used for optimization and control, and iron tapping is completed to produce qualified pig iron and by-products (slag, dust, and coal gas).

[0035] Comparative Example 1

[0036] The mass percentage of lump ore in the raw material is 16%, and the rest is sintered ore and pellets. The existing control method is used to put them into the furnace for smelting, and the iron is tapped to produce qualified pig iron and by-products (slag, dust, and coal gas).

[0037] The actual smelting data of the blast furnace in the above embodiment and the comparative example are shown in Table 1:

[0038] Table 1 Actual smelting data of blast furnace

[0039] category Lump ore ratio% <![CDATA[Utilization factor t / m 3 ·d]]> Coke ratio kg / t Coal ratio kg / t Fuel ratio kg / t Average silicon % Furnace grade % Pass rate% Gas utilization rate% Example 1 35 4.2 388 144 532 0.4 57.07 100.0 43.5 Example 2 37 4.2 389 147 536 0.41 56.95 100.0 43.4 Example 3 40 4.0 398 141 539 0.37 56.95 100.0 43.1 Comparative Example 1 16 4.5 357 170 527 0.31 57.55 100.0 45.1

[0040] It can be seen from Table 1 above that the pig iron smelted by the various embodiments of the method of the present application can meet the smelting qualification rate while increasing the proportion of lump ore, while reducing the use of clinker and the process energy consumption in the smelting process, which is more low-carbon, energy-saving and environmentally friendly. The present invention can efficiently and accurately adjust a series of adverse effects on the blast furnace brought about by the production of high-proportion lump ore, ensure stable operation of the furnace condition in the production of high-proportion lump ore, achieve the new goal of reducing the cost per ton of iron, create greater economic benefits for the company, and also point out the direction and set a new benchmark for the charge structure of the blast furnace ironmaking industry.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions should also be deemed to fall within the protection scope of the technical solution of the present invention.

Claims

1. A blast furnace smelting method using an ultra-high lump ore ratio, characterized in that: The steps include: (1) Raw material control: The mass percentage of lump ore in the raw material is controlled to be 35%~40%, and the rest is sintered ore. The quality of lump ore and sintered ore in the raw material is selectively controlled, where the basicity R2 of the sintered ore is 1.95±0.05, the grade is not less than 54.5%, the slag-iron ratio is controlled to be ≤310kg / t, the moisture content of lump ore is not higher than 5%, the burn loss is not higher than 8%, and the powder content of lump ore raw material entering the furnace <5mm does not exceed 5%, and 5mm~10mm does not exceed 25%; all fuel coke is dry quenched, and the moisture content of dry quenched coke is controlled to be no higher than 1.5%; (2) Loading system: gradually reduce the ore belt, gradually adopt a loading system that loosens the edge and guides the center airflow, and adjust the order of distribution; (3) Air supply system: reduce the air outlet area by 3% to 5% and ensure that the actual wind speed is not less than 240m / s and the actual kinetic energy of the air is not less than 62KJ / S; (4) Oxygen enrichment balance system: reduce the oxygen enrichment of the blast air, maintain the theoretical combustion temperature at 2280℃~2300℃, and transfer the reduced oxygen enrichment of the blast air to the hot blast furnace for oxygen-enriched combustion operation, and adjust the air temperature in the hot blast furnace accordingly; (5) Slag iron smelting system: control the silicon content in molten iron to 0.3%~0.5%, the sulfur content to 0.02%~0.04%, the molten iron temperature to not less than 1490℃, the slag basicity to 1.25±0.03, and control the slag magnesium-aluminum ratio to not less than 0.60%, and the slag temperature to not less than 1520℃.

2. A blast furnace smelting method using an ultra-high lump ore ratio according to claim 1, characterized in that: Before the lump ore is fed to the blast furnace trough, it is pre-screened by a vibrating screen with a screen gap of 8 mm to reduce the powder content of the lump ore in advance, and a drying system is used to further reduce the moisture content of the lump ore. The frequency of cleaning the lump ore is increased, the vibrating screen is vibrated in advance, and the feeding speed is controlled subsequently.

3. A blast furnace smelting method using an ultra-high lump ore ratio according to claim 2, characterized in that: The feeding speed control is specifically as follows: the overall feeding speed of ore raw materials is not more than 13kg / s, the feeding speed of fuel coke is not more than 10kg / s, and when the screening particle size under the trough does not meet the requirements, the screening speed is controlled by timely adjusting the movable gate.

4. A blast furnace smelting method using an ultra-high lump ore ratio according to claim 1, characterized in that: The raw material distribution system of the blast furnace in (2) is C3 38.5 3 36 2 33 2 30 2 26 O3 37.5 3 34.5 2 31.5 2 28.5 Adjusted to C4 38 3 35.5 2 32.5 2 29.5 2 26. 5 O2 35.5 3 33.5 3 31 2 28.5 The angle difference was adjusted from 0.62 to -1.68, the ore belt was reduced from 9° to 6°, and the order of distribution was adjusted at the same time. The block ore was distributed in the middle ore belt, and there were small coke pieces in the ore belt.

5. The blast furnace smelting method using ultra-high lump ore ratio according to claim 1, characterized in that: The oxygen enrichment of the blast in (4) is reduced to 6000m 3 / min, the air temperature in the hot blast furnace is controlled at 1210℃~1240℃.