Addition and use method of particle steel

Abstract

The invention relates to the technical field of sintering ironmaking, in particular to a particle steel adding and using method which comprises the steps that firstly, particle steel is screened, and an oversize part and an undersize part are obtained; secondly, the oversize part and one or more of sintered ore, pellet ore and lump ore are mixed and then enter a blast furnace to be smelted; and the undersize part and the sintered ore are mixed and then enter a sintering machine to be sintered. According to the method, the particle steel with different granularities is screened and then used for the blast furnace smelting procedure and the sintering procedure, on the premise that stable operation of the sintering procedure and the blast furnace smelting procedure is guaranteed, the pretreatment procedure of the particle steel is simplified, and the machining cost and energy consumption of the particle steel are reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sintering ironmaking, and in particular to a method for adding and using particle steel. Background Art

[0002] Particle steel is a by-product of the steel industry and manufacturing industry. Its main sources include steel slag selection products, steel flame feed oxidized slag, welding iron oxide and iron filings after cold processing of steel. Particle steel has the characteristics of low impurity content, easy melting and high cost-effective raw material. It is generally used to replace traditional scrap steel in the steelmaking process. Particle steel has a finer particle size, less than 20mm, and contains a large amount of steel slag with a particle size of less than 5mm. The slag content is about 15%-40%, which is much higher than the slag content of other types of scrap steel used in the steelmaking process. If particle steel is used directly in the steelmaking process, a large amount of steel slag will increase the flux consumption during the steelmaking process, and the increase in the amount of steelmaking slag will take away a large amount of physical heat, thereby increasing the energy consumption of the steelmaking process. The existing technology usually adopts the method of hot-melt briquetting, in which the particle steel is heated to about 700°C and then pressed into a ф30×30 (or other specifications) cylinder and added to the converter to participate in steelmaking. The processing cost is relatively high. In addition, since the briquette particle steel contains metallic iron and iron oxides, and the iron content is between 60% and 85%, the use of briquette particle steel for steelmaking will also reduce the metal recovery rate of the converter scrap steel and increase the converter smelting cost.

[0003] Chinese patent CN118345208A discloses a method for adding scrap steel to a blast furnace, wherein the scrap steel is first pre-treated to control the particle size of the scrap steel to 5-100 mm, and then the scrap steel with a particle size of 5-100 mm is added to the iron ditch in front of the blast furnace, and gradually melted into molten iron on the way to the torpedo tank with the molten iron, completing the addition of scrap steel. The patent uses particle steel with a particle size of 5-100 mm in the blast furnace ironmaking process, which increases the blast furnace molten iron output to a certain extent, but adding particle steel in the molten iron ditch will cause the molten iron temperature to decrease, resulting in heat loss of the molten iron, affecting the thermal balance of the subsequent steelmaking process. When the particle size of the particle steel is less than 5 mm, using the method disclosed in the patent to treat the particle steel will not only increase the temperature drop, but also cause molten iron to splash, causing safety accidents. Summary of the invention

[0004] In view of the technical problem in the prior art that adding particle steel with a particle size greater than 5 mm into molten iron for blast furnace smelting easily leads to heat loss of molten iron, the present invention provides a method for adding and using particle steel, wherein particle steels of different particle sizes are screened and used in a blast furnace smelting process and a sintering process respectively, and under the premise of ensuring the smooth operation of the sintering process and the blast furnace smelting process, the pretreatment process of the particle steel is simplified, and the processing cost and energy consumption of the particle steel are reduced.

[0005] The technical solution of the present invention is as follows: A method for adding and using particle steel comprises the following steps: Step 1: Screening the particle steel to obtain an oversize portion and an undersize portion; Step 2: The part above the screen is mixed with one or more of sintered ore, pelletized ore, and lump ore and then enters the blast furnace for smelting; the part below the screen is mixed with sintered ore and then enters the sintering machine for sintering.

[0006] Furthermore, in step 1, the particle steel is air-dried and then screened, and the moisture content of the particle steel after air-dried is ≤1.0wt%. The present invention uses air-dried method to control the moisture content of the particle steel at a low level, so that the particle steel is fully dried and has good fluidity, thereby improving the screening efficiency of the particle steel.

[0007] Furthermore, in step 1, the particle steel is screened using a vibrating screen, and the mesh size of the vibrating screen is 5-10 mm, preferably 5 mm.

[0008] Furthermore, in step 2, the mass percentage of the oversize portion in the total charge of the blast furnace is ≤2%.

[0009] Furthermore, in step 2, the mass percentage of the undersize portion in the total batching amount of the sintering machine is ≤3%.

[0010] Furthermore, in step 2, the screened part is mixed with one or more of sintered ore, pelletized ore, and lump ore and then fed into the blast furnace for smelting through the furnace top feeding system.

[0011] Furthermore, in step 2, after the screened portion is mixed with the sintered ore, it is first sent to a mixer for uniform mixing, and then sent to a sintering machine for sintering.

[0012] Furthermore, the iron content TFe of the particle steel is ≥60wt%, and the particle size range of the particle steel is 3-20mm.

[0013] The beneficial effects of the present invention are: The invention provides a method for adding and using particle steel, which adopts screening to divide the particle steel into an over-sieve part with relatively large particle size and an under-sieve part with relatively small particle size. The over-sieve part with relatively large particle size is used for blast furnace smelting. On the one hand, it can improve the softening temperature of blast furnace charge, reduce the dripping temperature, narrow the softening temperature range and the molten drop temperature range, reduce the maximum pressure difference, improve the soft melting dripping performance of blast furnace charge, and facilitate the stable and smooth operation of the blast furnace. On the other hand, since the iron element in the particle steel exists in the form of metal rather than oxide, the use of the particle steel for blast furnace smelting is also beneficial to reducing fuel consumption and molten iron cost; the under-sieve part with relatively small particle size is used for sintering in a sintering machine, and on the premise of simplifying the pretreatment process of the particle steel, the drum index of the sintered ore is improved, which is beneficial to improving the strength of the sintered ore. The particle steel with smaller particle size can be used for blast furnace smelting after sintering treatment, avoiding the adverse effects of directly using the particle steel with smaller particle size for blast furnace smelting on the permeability of the charge and the smooth operation of the furnace condition. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0015] Example 1 A method for adding and using particle steel comprises the following steps: Step 1: First, the particle steel is fully dried by airing, and the moisture content of the particle steel is controlled below 1.0wt%, and then the particle steel is screened using a vibrating screen with a mesh size of 5mm to obtain the upper and lower parts. Particle steel is a particle steel used for smelting in the steel industry. Particle steel mainly comes from iron-containing materials obtained after crushing and magnetic separation of steel slag. The iron content TFe of particle steel is 60wt%-85wt%, and the particle size range is 3-20mm. Particle steel meets the requirements of GB / T 4223-2017 for scrap steel. The main components and mass percentages of particle steel are shown in Table 1.

[0016] Table 1 Main components and mass percentage of particle steel

[0017] Step 2: Conduct a molten droplet performance test on the particle steel above the screen for blast furnace matching, to test whether the particle steel above the screen for blast furnace matching meets the requirements of blast furnace production for the metallurgical properties of the ore, the reference standard for the test method is GB / T34211-2017, the particle steel above the screen is matched with the sintered ore, to obtain blast furnace charge 1, blast furnace charge 2, and blast furnace charge 3 with the mass percentages of the particle steel above the screen being 0%, 1%, and 2%, respectively. The main components and mass percentages of the sintered ore are shown in Table 2, and the soft melting dripping performance tests are conducted on blast furnace charge 1, blast furnace charge 2, and blast furnace charge 3, respectively, and the test results are shown in Table 3.

[0018] Table 2 Main chemical components and mass percentages of sintered ore in Example 1

[0019] Table 3 Soft melting dripping performance test results of blast furnace charge 1 to blast furnace charge 3

[0020] As shown in Table 3, compared with the blast furnace charge 1 without adding particle steel, the softening start temperature T 10 and the melting start temperature T S Increase, melting range (T D -T S ) is reduced; compared with blast furnace charge 1, the softening range of blast furnace charge 2 (T S -T 10 ) increases, while the sum of the softening range and the melting range does not change, affecting the melting range (T D -T S ) is reduced, so blast furnace charge 2 is beneficial to improving the permeability of the blast furnace soft melting zone. Compared with blast furnace charge 2, the softening start temperature T 10 and the melting start temperature T S Higher, melting range (T D -T S The above results show that with the increase of the proportion of particle steel added in the screen part, the permeability of the soft melting zone and the smoothness of the furnace condition of the blast furnace charge are better. The main reason is that the increase of the proportion of particle steel added in the screen part will lead to a decrease in the amount of shrinkable sintered ore, which makes the corresponding temperature increase when the shrinkage rate is the same, and the temperature corresponding to the sudden increase in pressure difference caused by the shrinkage of sintered ore also increases. The dripping temperature is reduced because the particle steel in the screen part is more easily carburized and melted, thereby narrowing the softening range and the melting range, which is beneficial to improving the permeability of the soft melting zone and strengthening smelting in the blast furnace.

[0021] The sintering addition of the particle steel under the screen is subjected to a sintering cup test. The reference standard for the sintering cup test method is YB / T 4852-2020. The metallurgical properties of the sintered ore after the addition of particle steel in the sintering process are tested to see whether they meet the requirements. The sintering raw materials in which the mass percentage of particle steel under the screen accounts for 0%, 1%, and 2% of the sintering raw materials are marked as sintering raw material 1, sintering raw material 2, and sintering raw material 3, respectively. The sintering cup test is performed on sintering raw material 1, sintering raw material 2, and sintering raw material 3, respectively. The main raw materials and mass percentages in sintering raw material 1, sintering raw material 2, and sintering raw material 3 are shown in Table 4, among which the main ore components and mass percentages of mineral powder 1-ore powder 9 are shown in Table 5, the main components and mass percentages of flux 1-flux 3 are shown in Table 6, and the main components and mass percentages of fuel are shown in Table 7. The results of the sintering cup test of sintering raw materials 1-sintering raw materials 3 are shown in Table 8.

[0022] Table 4 Main raw materials and mass percentages in sintering raw materials 1 to sintering raw materials 3

[0023] Table 5 Main mineral components and mass percentages of mineral powder 1 to mineral powder 9

[0024] Table 6 Main components and mass percentages of flux 1 to flux 3

[0025] Table 7 Main components and mass percentage of fuel

[0026] Table 8 Sintering cup test results of sintering raw materials 1 to sintering raw materials 3

[0027] As shown in Table 8, after adding the particle steel from the undersize part during sintering, the various indicators of the sintered ore do not change much, which meets the quality requirements of the sintered ore, and the drum index of the sintered ore is improved, indicating that adding the particle steel from the undersize part during sintering is beneficial to improving the strength of the sintered ore.

[0028] Step 3: After screening, weigh the weight of the part above the screen and the part below the screen respectively. After weighing, the particle steel of the part above the screen is added to the blast furnace bunker from the external charging port or other channels of the blast furnace for standby use as raw materials for blast furnace production; the particle steel of the part below the screen is transported to the batching bunker of the sintering batching workshop by the feeding belt and the dividing belt of the sintering batching workshop as raw materials for sintering production. According to the blast furnace charge structure, the particle steel of the part above the screen in the blast furnace bunker is batched with the sintered ore to obtain the blast furnace charge. The mass percentage of the particle steel of the part above the screen in the blast furnace charge is 0%, 1%, and 2%, respectively. The blast furnace charge is added to the furnace top charge tank using the feeding belt, and added to the blast furnace through the furnace top feeding system for smelting. The particle steel of the part below the screen and the sintered ore are added to the mixing belt, sent to the mixer and mixed evenly to obtain the sintering raw material, wherein the mass percentage of the particle steel of the part below the screen in the sintering raw material is 0%, 1%, and 2%, respectively. Application Example 1 A method for adding and using a particle steel is used for 265m 2 Sintering machine with 1880m 3 Blast furnace ironmaking system, the specific steps are as follows: The oversize and undersize parts in Example 1 were loaded onto a transport truck using a loader, and the oversize part was weighed during transportation. The cumulative weight of the oversize part was 1582t. After weighing, the oversize part was transported to the external charging port of the blast furnace and 1880m 3 The blast furnace raw material silo is ready for use. The particle steel on the screen is prepared according to the ratio of sintered ore: pelletized ore: lump ore: particle steel on the screen = 75:10:19:1. During the blast furnace smelting production process, the blast furnace raw material batch is 52.5t, and the amount of each batch of blast furnace raw materials is 37.5t of sintered ore, 5t of pelletized ore, 9.5t of lump ore, and 0.5t of particle steel on the screen. Use the feeding belt to prepare the blast furnace raw materials and add them to the blast furnace receiving silo. The production preparation is completed through the furnace top feeding system and enters the blast furnace for smelting. The part under the screen is transported to 265m 2 In the sintering machine batching workshop, after weighing, it is fed into the batching bin through the feeding belt and the powder belt, and after batching with the sintering ore, it is sent to the mixer for uniform mixing to obtain the sintering raw material, and the sintering raw material enters the sintering machine for sintering. The particle steel under the screen accounts for 2% of the mass percentage of the sintering raw material, and the composition and mass percentage of the sintering raw material are the same as those of sintering raw material 3. The production amount of particle steel is 4000t.

[0029] Application Example 2 A method for adding and using a particle steel is used in 480m 2 Sintering machine with 3800m 3 Blast furnace ironmaking system, the specific steps are as follows: The oversize and undersize parts in Example 1 were loaded onto a transport truck using a loader, and the oversize part was weighed during transportation. The cumulative weight of the oversize part was 1592t. After weighing, the oversize part was transported to the external charging port of the blast furnace and charged with 3800m 3 The blast furnace raw material silo is ready for use. The particle steel on the screen is prepared according to the ratio of sintered ore: pelletized ore: lump ore: particle steel on the screen = 70:13:16:1. In the blast furnace smelting production process, the blast furnace raw material batch is 100t, and the amount of each batch of blast furnace raw materials is 70t of sintered ore, 13t of pelletized ore, 16t of lump ore, and 1t of particle steel on the screen. Use the feeding belt to prepare the blast furnace raw materials and add them to the blast furnace receiving silo. The production addition is completed through the furnace top feeding system and enters the blast furnace for smelting. The part under the screen is transported to 480m 2 In the sintering machine batching workshop, after weighing, it is fed into the batching bin via the feeding belt and the powder belt, and after batching with the sintering ore, it is sent to the mixer for uniform mixing to obtain the sintering raw material, and the sintering raw material enters the sintering machine for sintering. The particle steel under the screen accounts for 1% of the mass percentage of the sintering raw material, and the composition and mass percentage of the sintering raw material are the same as those of sintering raw material 2. The production amount of particle steel is 5000t.

[0030] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A method for adding and using particle steel, characterized in that: The steps include: Step 1: Screening the particle steel to obtain an oversize portion and an undersize portion; Step 2: The part above the screen is mixed with one or more of sintered ore, pelletized ore, and lump ore and then enters the blast furnace for smelting; the part below the screen is mixed with sintered ore and then enters the sintering machine for sintering.

2. The method for adding and using particle steel according to claim 1, characterized in that: In step 1, the particle steel is air-dried and then sieved, and the moisture content of the particle steel after air-dried is ≤1.0wt%.

3. The method for adding and using particle steel as claimed in claim 1, characterized in that: In step 1, the particle steel is screened using a vibrating screen, and the mesh size of the vibrating screen is 5-10 mm.

4. The method for adding and using particle steel as claimed in claim 1, characterized in that: In step 2, the mass percentage of the oversize portion in the total charge of the blast furnace is ≤2%.

5. The method for adding and using particle steel as claimed in claim 1, characterized in that: In step 2, the mass percentage of the undersize portion in the total batching amount of the sintering machine is ≤3%.

6. The method for adding and using particle steel as claimed in claim 1, characterized in that: In step 2, the screened part is mixed with one or more of sintered ore, pelletized ore and lump ore and then enters the blast furnace for smelting through the furnace top feeding system.

7. The method for adding and using particle steel as claimed in claim 1, characterized in that: In step 2, after the screened part is mixed with the sintered ore, it is first sent to a mixer for uniform mixing and then sent to a sintering machine for sintering.

8. The method for adding and using particle steel as claimed in claim 1, characterized in that: The iron content of the particle steel is TFe≥60wt%, and the particle size range of the particle steel is 3-20mm.

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