Preparation method of gradient slow-release dephosphorizing agent

Abstract

The invention discloses a preparation method of a gradient slow-release dephosphorizing agent, which specifically comprises the following steps: (1) crushing and uniformly mixing the dephosphorizing agent, loading the dephosphorizing agent into a steel pipe with one sealed end, and pressing the steel pipe to a compact state; (2) the steel pipe is placed on a section cutting table, and the steel pipe is cut into dephosphorization agent blocks with a certain length through a section cutting knife; and (3) carrying out gradient matching on the dephosphorizing agent blocks with different pipe wall diameters and different pipe wall thicknesses to obtain the gradient slow-release dephosphorizing agent. The dephosphorizing agent can be conveniently and effectively added, the dephosphorizing effect of the dephosphorizing agent is improved, the reaction time is shortened, the production cost is reduced, and the product quality is improved, so that the problems of slow lime melting and low dephosphorizing efficiency in the converter smelting process and the problems of easy floating of carbon powder and less gasification dephosphorizing during converter slag splashing for converter protection are effectively solved; and other processes or methods can increase the production cost, influence the production technical indexes and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of iron and steel metallurgy, and more specifically to a preparation method of a gradient slow-release dephosphorizer. Background Art

[0002] The presence of phosphorus in steel will reduce the plasticity and toughness of the steel. Therefore, during the converter steelmaking process, dephosphorization treatment must be carried out to ensure that the molten steel composition meets the requirements of the steel grade. As the main raw material for converter dephosphorization, lime is added to the converter through two methods: adding through the upper bunker and bottom blowing. During the steelmaking process, lime and other slag-making agents are directly added from the high-position bunker, requiring the slag materials to have a certain particle size. In the early stage of converter smelting, the temperature is relatively low, and the added lime has a solidification process, which is not conducive to the rapid melting of lime. For the bottom-blown lime powder dephosphorization technology, although the dephosphorization efficiency is high, the transformation of the bottom-blown powder process equipment is difficult, the process operation requirements are high, the production cost is high, and the domestic maintenance system is not mature. Moreover, it has high requirements for the quality of the bottom-blown lime powder, and the production cost is relatively large.

[0003] After the converter steelmaking is completed, some enterprises use the gasification dephosphorization technology during the slag splashing and furnace lining protection process to restore the activity of the molten slag. The gasification dephosphorization process can remove phosphorus elements in the molten slag, improve the quality of molten steel, and the treated furnace slag can be recycled to reduce the solid waste treatment cost. The main problem of the furnace slag gasification dephosphorization technology is that it is difficult to add the gasification dephosphorizer. The bagged dephosphorizer often floats on the molten slag and is lost greatly with the slag splashing and furnace lining protection gas, increasing the operation difficulty and complexity of gasification dephosphorization, and the dephosphorization effect does not reach the ideal effect.

[0004] From the above analysis, it can be seen that on the basis of ensuring the stable operation of the existing production process, it is of great significance to research and develop new dephosphorizers. Effective hot metal and furnace slag dephosphorization treatment technologies can reduce the smelting production cost, improve production efficiency, and meet the increasingly strict requirements for steel quality.

[0005] Therefore, how to effectively carry out converter molten steel dephosphorization and furnace slag dephosphorization is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a preparation method of a gradient slow-release dephosphorizer to solve the deficiencies in the prior art.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A preparation method of a gradient slow-release dephosphorizer specifically includes the following steps:

[0009] (1) Crush and mix the dephosphorizer, load it into a steel pipe with one end sealed, and press it to a dense state;

[0010] (2) Place the steel pipe on the cutting table and cut the steel pipe into dephosphorizer blocks of a certain length by the cutting knife.

[0011] (3) Gradiently match the dephosphorizer blocks with different pipe wall diameters and different pipe wall thicknesses, and the gradient slow-release dephosphorizer is obtained.

[0012] Furthermore, in the above step (1), the dephosphorizer is an iron melt dephosphorizer or a slag dephosphorizer.

[0013] Even further, the above iron melt dephosphorizer includes 4-6 parts of active lime powder, 1-2 parts of dolomite powder or calcium carbonate powder, and 1-2 parts of mill scale.

[0014] The beneficial effect of adopting the above is that the selected iron melt dephosphorizer of the present invention has fine particles, is easier to melt and dephosphorize, and can significantly improve the converter dephosphorization rate and the quality of steel.

[0015] Even further, the above slag dephosphorizer is composed of carbon powder and slag dephosphorizer ingredients. Among them, the mass ratio of carbon powder is 80%-85%, and the balance is slag dephosphorizer ingredients; the slag dephosphorizer ingredients are ferrosilicon or aluminum ash or other reducing agents.

[0016] The beneficial effect of adopting the above is that the selected slag dephosphorizer of the present invention can significantly improve the utilization rate of carbon powder and the dephosphorization rate, further shorten the dephosphorization time and reduce the production cost.

[0017] Furthermore, in the above step (1), the material of the steel pipe is low-carbon steel, the pipe wall diameter is 20-100 mm, the pipe wall thickness is 0.5-8 mm, and the inside of the pipe is filled with iron melt dephosphorizer or slag dephosphorizer.

[0018] Furthermore, in the above step (2), the cutter teeth of the cutting knife are in a "mountain" shape, and the steel pipe is squeezed up and down by the cutting knife to form blocks.

[0019] Furthermore, in the above step (2), the length of the dephosphorizer block is 10-100 mm, and both ends are closed.

[0020] Furthermore, in the above step (3), the operation of gradient matching is specifically as follows: Gradiently match the dephosphorizer blocks with different pipe wall diameters in three gradients of large, medium, and small, and gradiently match the dephosphorizer blocks with different pipe wall thicknesses in three gradients of thick, medium, and thin.

[0021] It can be seen from the above technical solutions that compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. High-efficiency dephosphorization: Different packages of dephosphorizer can be selected for molten iron at different temperatures, making the dephosphorizer easy to melt and form slag, and improving the dephosphorization efficiency.

[0023] 2. Improve production efficiency: The production process can be further optimized, shortening the entire smelting cycle and improving the production capacity of the converter.

[0024] 3. Improve the quality of steel: Phosphorus is a harmful element in steel, which will reduce the impact toughness of steel. The dephosphorizer of the present invention can effectively remove phosphorus elements in steel, improve the purity and quality of steel, improve the performance of steel, and can produce high-quality steel grades with strict requirements, meeting the needs of different industries for high-quality steel.

[0025] 4. The operation process of the present invention is simple and practical, which is of great benefit to the optimization of the subsequent converter smelting process, solves the problems of effective addition and efficient reaction of the dephosphorizer, significantly improves the smelting dephosphorization rate, and reduces the production cost at the same time.

[0026] 5. The present invention can facilitate the effective addition of the dephosphorizer, improve the dephosphorization effect of the dephosphorizer, shorten the reaction time, reduce the production cost, improve the product quality, and thus effectively solve the problems of slow lime melting and low dephosphorization efficiency during the converter smelting process, the problem that carbon powder is easy to float and less gasification dephosphorization occurs during the slag splashing and furnace lining protection of converter slag, and other processes or methods that will increase the production cost and affect the production technical indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic flow chart of the preparation method of the gradient slow-release dephosphorizer in Examples 1-3; wherein, 1 - dephosphorizer (hot metal dephosphorizer or slag dephosphorizer), 2 - steel pipe, 3 - cutter teeth, 4 - dephosphorizer block, 5 - cutting knife.

[0028] Figure 2 It is a schematic structural diagram of the cutting knife in Examples 1-3;

[0029] Figure 3 It is a physical diagram of sampling and temperature measurement in the dephosphorization test;

[0030] Figure 4 It is a physical diagram of adding the dephosphorizer in the dephosphorization test;

[0031] Figure 5 It is a physical diagram of the gradient slow-release dephosphorizer sample in the dephosphorization test;

[0032] Figure 6 It is an SEM image of the surface of the dephosphorization slag of the traditional dephosphorizer;

[0033] Figure 7 It is an EDS image of the surface of the dephosphorization slag of the traditional dephosphorizer;

[0034] Figure 8 It is an SEM image of the surface of the dephosphorization slag of the gradient slow-release dephosphorizer;

[0035] Figure 9 It is an EDS image of the surface of the dephosphorization slag of the gradient slow-release dephosphorizer. Detailed implementation manners

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] Embodiment 1

[0038] A preparation method of a gradient slow-release dephosphorizer specifically includes the following steps:

[0039] (1) Crush and mix 5 kg of active lime powder, 1 kg of dolomite powder and 1 kg of mill scale to obtain a hot metal dephosphorizer 1, load it into a low-carbon steel pipe 2 with one end sealed, and press it to a dense state;

[0040] (2) Place the steel pipe 2 on a cutting table, and use a cutting knife 5 to cut the steel pipe 2 into dephosphorizer blocks 4 with lengths of 10 mm, 60 mm and 100 mm respectively and both ends closed;

[0041] Among them, the cutter teeth 3 of the cutting knife 5 are in a "mountain" shape, and the steel pipe 2 is squeezed up and down by the cutting knife 5 to form a block;

[0042] (3) Gradiently match the dephosphorizer blocks 4 with pipe wall diameters of 20 mm, 40 mm, 80 mm and pipe wall thicknesses of 0.5 mm, 1 mm, 2 mm respectively, and the gradient slow-release dephosphorizer is obtained.

[0043] Embodiment 2

[0044] A preparation method of a gradient slow-release dephosphorizer specifically includes the following steps:

[0045] (1) Crush and mix 5 kg of active lime powder, 2 kg of calcium carbonate powder and 2 kg of mill scale to obtain a hot metal dephosphorizer 1, load it into a low-carbon steel pipe 2 with one end sealed, and press it to a dense state;

[0046] (2) Place the steel pipe 2 on a cutting table, and use a cutting knife 5 to cut the steel pipe 2 into dephosphorizer blocks 4 with lengths of 60 mm, 80 mm and 100 mm respectively and both ends closed;

[0047] Among them, the cutter teeth 3 of the cutting knife 5 are in a "mountain" shape, and the steel pipe 2 is squeezed up and down by the cutting knife 5 to form a block;

[0048] (3) Gradiently match the dephosphorizer blocks 4 with pipe wall diameters of 40 mm, 60 mm, 80 mm and pipe wall thicknesses of 4 mm, 6 mm, 8 mm respectively, and the gradient slow-release dephosphorizer is obtained.

[0049] Example 3

[0050] The preparation method of the gradient slow-release dephosphorizer specifically includes the following steps:

[0051] (1) Crush and mix 8 kg of carbon powder and 2 kg of ferrosilicon to obtain the slag dephosphorizer 1, load it into the low-carbon steel pipe 2 with one end sealed, and press it to a dense state;

[0052] (2) Place the steel pipe 2 on the cutting table, and use the cutting knife 5 to cut the steel pipe 2 into dephosphorizer blocks 4 with lengths of 20 mm, 40 mm, and 60 mm respectively and both ends closed;

[0053] Among them, the cutter teeth 3 of the cutting knife 5 are in a "mountain" shape, and the steel pipe 2 is squeezed up and down by the cutting knife 5 to form a block;

[0054] (3) Gradiently match the dephosphorizer blocks 4 with pipe wall diameters of 20 mm, 40 mm, 60 mm and pipe wall thicknesses of 2 mm, 4 mm, 6 mm respectively to obtain the gradient slow-release dephosphorizer.

[0055] Performance test

[0056] Use a 150 kg intermediate frequency induction furnace to carry out the dephosphorization test of the traditional dephosphorizer and the gradient slow-release dephosphorizer.

[0057] 1 Test preparation

[0058] 1.1 Iron block

[0059] Prepare 100 kg of iron blocks, and its main components are shown in Table 1.

[0060] Table 1 Main components of iron block (average mass fraction)

[0061] Element C Si Mn P S Others Content (%) 4.17 0.45 0.26 0.13 0.017 Remainder

[0062] 1.2 Dephosphorizer

[0063] Prepare the hot metal dephosphorizer (5 kg of active lime powder, 1 kg of dolomite powder and 1 kg of mill scale), and its main components are shown in Table 2.

[0064] Table 2 Main components of dephosphorizer (average mass fraction)

[0065] Phosphorus removal agent FeO CaO <![CDATA[Si2O]]> MgO S Others Active lime powder - 85.5 2.5 1.5 0.048 Remainder Dolomite powder - 48 2.5 28 0.12 Remainder Mill scale 51.42 1.17 2.44 0.58 - Remainder

[0066] 1.2.1 Traditional dephosphorizer

[0067] Crush and mix 5 kg of active lime powder, 1 kg of dolomite powder and 1 kg of mill scale to obtain the traditional dephosphorizer with a particle size of 5-20 mm.

[0068] 1.2.2 Gradient slow-release dephosphorizer

[0069] Crush and mix 5 kg of active lime powder, 1 kg of dolomite powder and 1 kg of mill scale to obtain a dephosphorizer with a particle size of 0.5 mm. Then, according to the method of Example 1, it is made into a gradient slow-release dephosphorizer, which consists of two blocks with a diameter of 10 mm, a length of 20 mm, a wall thickness of 0.5 mm and a diameter of 20 mm, a length of 20 mm and a wall thickness of 1 mm.

[0070] 1.3 Slag

[0071] The slag basicity is 3.0 - 3.5, and the oxygen supply intensity is 3.48 Nm 3 / (min·t).

[0072] 2 Test steps

[0073] (1) Add 100 kg of iron blocks into the furnace, send electricity to heat up and melt the iron blocks. When all the iron blocks are melted, measure the temperature (as Figure 3 shown). When the temperature is higher than 1400 °C, add mill scale to lower the temperature so that the molten iron temperature ≤ 1400 °C. Start lowering the lance to blow oxygen and add the first one-third of the dephosphorizer (as Figure 4 shown), pre-melt the dephosphorizer, and the lance position is 10 - 20 mm lower than the standard lance position (the standard lance position is 460 mm);

[0074] (2) Add one-third of the dephosphorizer every 3 minutes, and control the lance position of the oxygen lance to the standard lance position according to the liquid level in the furnace. During this period, measure the temperature every 1.5 minutes so that the molten iron temperature ≤ 1400 °C. After 6 minutes of blowing, the addition of the dephosphorizer is completed, the slag making is completed, take a slag sample and conduct observation and detection;

[0075] (3) After the slag making is completed, raise the lance position of the oxygen lance by 10 - 20 mm according to the liquid level in the furnace. As the temperature of the molten pool continues to rise, when the temperature rises to 1460 °C, stop oxygen supply, take a sample and detect the phosphorus content.

[0076] 3 Test results

[0077] 3.1 Phosphorus element detection

[0078] Detect the phosphorus element in two furnace samples. The phosphorus content of the traditional dephosphorizer sample is 0.021%, and its dephosphorization rate is 84%; the phosphorus content of the gradient slow-release dephosphorizer sample (as Figure 5 shown) is 0.013%, and its dephosphorization rate can reach 90%.

[0079] 3.2 Slag detection

[0080] Detect the slag of two furnaces, and the results are as Figures 6 - 9 shown.

[0081] From Figures 6 - 9It can be seen that by observing the surface morphology and element distribution of the dephosphorization slag of the traditional dephosphorizer and the gradient slow-release dephosphorizer, it can be found that the slag melting state of both is good. By detecting the furnace slag sample through EDS surface scanning, it can be found that phosphorus elements are evenly distributed in the dephosphorization slag of the traditional dephosphorizer and the gradient slow-release dephosphorizer. The EDS energy spectrum element mass fraction shows that within the same multiple and the same area, the mass fraction of phosphorus elements in the dephosphorization slag of the traditional dephosphorizer is 8%, and the mass fraction of phosphorus elements in the dephosphorization slag of the gradient slow-release dephosphorizer is 12%. The above tests show that when using the gradient slow-release dephosphorizer to make slag, the phosphorus element content in the furnace slag is higher in the early stage.

[0082] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a gradient slow-release dephosphorization agent, characterized in that: Specifically, it includes the following steps: (1) Crush and mix the dephosphorizer, load it into a steel pipe with one end sealed, and press it to a dense state; (2) Place the steel pipe on the cutting table, and cut the steel pipe into dephosphorizer blocks of a certain length through a cutting knife; (3) Gradiently match the dephosphorizer blocks with different pipe wall diameters and different pipe wall thicknesses, and the gradient slow-release dephosphorizer is obtained.

2. The method for preparing a gradient slow-release dephosphorization agent according to claim 1, characterized in that: In step (1), the dephosphorizer is an iron melt dephosphorizer or a slag dephosphorizer.

3. The method for preparing a gradient slow-release dephosphorization agent according to claim 2, characterized in that: The iron melt dephosphorizer includes 4-6 parts of active lime powder, 1-2 parts of dolomite powder or calcium carbonate powder, and 1-2 parts of mill scale.

4. The method for preparing a gradient slow-release dephosphorization agent according to claim 2, characterized in that: The slag dephosphorizer is composed of carbon powder and a slag dephosphorizer formulation. Among them, the mass ratio of the carbon powder is 80%-85%, and the balance is the slag dephosphorizer formulation; the slag dephosphorizer formulation is ferrosilicon or aluminum ash.

5. The method for preparing a gradient slow-release dephosphorization agent according to claim 1, characterized in that: In step (1), the material of the steel pipe is low-carbon steel, the pipe wall diameter is 20-100 mm, and the pipe wall thickness is 0.5-8 mm.

6. The method for preparing a gradient slow-release dephosphorization agent according to claim 1, characterized in that: In step (2), the cutting teeth of the cutting knife are in the shape of a "mountain", and the steel pipe is squeezed up and down by the cutting knife to form blocks.

7. The method for preparing a gradient slow-release dephosphorization agent according to claim 1, characterized in that: In step (2), the length of the dephosphorizer block is 10-100 mm, and both ends are closed.

8. The method for preparing a gradient slow-release dephosphorization agent according to claim 1, characterized in that: In step (3), the operation of the gradient matching is specifically as follows: Gradiently match the dephosphorizer blocks with different pipe wall diameters in three gradients of large, medium, and small, and gradiently match the dephosphorizer blocks with different pipe wall thicknesses in three gradients of thick, medium, and thin.

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