Low-cost dephosphorizing agent as well as preparation method and application thereof

Abstract

The invention provides a low-cost dephosphorizing agent and a preparation method and application thereof, and relates to the technical field of ferrous metallurgy, the dephosphorizing agent comprises the following components: 16-22 wt% of Fe3O4, 8-13 wt% of FeO, 4-8 wt% of Fe2O3, 46-53 wt% of CaO, less than or equal to 4 wt% of Na2O, less than or equal to 3 wt% of MgO, less than or equal to 3 wt% of Al2O3, less than or equal to 10 wt% of SiO2 and Slt; 0.1 wt%, Plt; 0.05 wt% of an additive; the raw materials of the dephosphorizing agent comprise a fixing agent, an oxidizing agent and a fluxing agent, the fixing agent is lime undersize powder for steelmaking desulfurization; the oxidizing agent is a surface oxide scale of a rolled steel billet; the fluxing agent is converter refining fly ash. All the raw materials are solid wastes in a plant or materials with low utilization value, and the prepared dephosphorizing agent has the characteristics of low cost, low melting point, high slag forming speed, environment friendliness and the like.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a low-cost dephosphorization agent and a preparation method and application thereof. Background Art

[0002] The presence of phosphorus in the steelmaking process will have many negative effects on the performance of steel. For example, excessive phosphorus content will increase the brittleness of steel, deteriorate welding performance, reduce ductility and plasticity, and shorten fatigue life, etc. Therefore, in order to ensure the quality of steel, the phosphorus content must be strictly controlled to reduce its harm. There are three main ways: one is source control, choosing low-phosphorus iron ore as raw material; the second is smelting process control, adding high-efficiency dephosphorization agents to the converter to promote phosphorus removal; the third is post-processing control, such as heat treatment of finished steel to improve its mechanical properties, reduce the brittleness caused by phosphorus, or consider using different alloying elements to strengthen the toughness of the material to compensate for the adverse effects of phosphorus.

[0003] After decades of mining, iron ore resources have shown a trend of gradual reduction, especially the depletion of high-quality resources has become increasingly obvious, objectively leading to higher and higher prices for low-phosphorus iron ore. Therefore, although it is desirable to control phosphorus at the source, it means high costs; post-processing to reduce phosphorus hazards can only correct steel performance to a certain extent, and the treatment effect of steel with excessively high phosphorus content is not obvious, and the cost of using alloying elements is too high; after practical verification, it is relatively economical to use dephosphorization agents to reduce the phosphorus content of steel during converter smelting. Traditional dephosphorization agents are generally divided into lime series and soda series. The soda series is prone to ladle lining erosion during use and has a high cost. Although the lime series has a relatively low cost, the unit price of purchased dephosphorization agents is still more than several thousand yuan. Summary of the invention

[0004] The invention aims to provide a low-cost dephosphorizing agent and a preparation method and application thereof. The raw materials used include lime undersize powder for steelmaking desulfurization, rolled steel billet iron oxide scale and converter refining dust, etc., wherein the lime undersize powder has low activity and is not valuable for repeated use in desulfurization; the iron oxide scale is mainly produced by surface oxidation and shedding of steel billets during rolling, and is generally mixed with grease and sundries, and is conventionally used for ironmaking sintering. During the sintering process, the grease is heated and volatilized to cause environmental pollution; the converter refining dust contains a high level of Na2O, belongs to solid waste, and is difficult to be harmlessly treated. Several raw materials are pressed into balls by a ball press according to a certain ratio with the aid of an adhesive, and are then used in the converter. The converter has the characteristics of low cost, low melting point, fast slag formation, environmental protection, and the like.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a low-cost dephosphorization agent, wherein the components of the dephosphorization agent include, by mass percentage: Fe3O4 16-22wt%, FeO 8-13wt%, Fe2O3 4-8wt%, CaO46-53wt%, Na2O≤4wt%, MgO≤3wt%, Al2O3≤3wt%, SiO2≤10wt%, S<0.1wt%, P<0.05wt%;

[0007] The dephosphorization agent raw materials include a fixing agent, an oxidizing agent and a flux;

[0008] The fixing agent is lime powder used for steelmaking desulfurization, and its main component is CaO;

[0009] The oxidant is the surface iron oxide scale of the rolled steel billet, and its main components are Fe3O4, Fe2O3 and FeO;

[0010] The flux is converter refining dust, and its main components are CaO, Na2O, MgO and Al2O3.

[0011] Furthermore, the CaO content in the lime undersize powder for steelmaking desulfurization is 75-90wt% and the particle size is less than 3mm.

[0012] Furthermore, the contents of Fe3O4, Fe2O3 and FeO in the surface iron oxide scale of the rolled steel billet are 50-62wt%, 13-22wt% and 25-35wt% respectively.

[0013] Furthermore, the contents of Na2O and MgO in the converter refining dust removal ash are 15-23wt%, 8-15wt%, and 45-53wt% respectively; and the particle sizes are 5-30μm respectively.

[0014] Furthermore, the preparation method of the dephosphorization agent includes raw material weighing, batching, mixing and pressing processes.

[0015] The second aspect of the present invention provides a method for preparing the low-cost dephosphorization agent according to the first aspect, comprising the following steps:

[0016] S1. Calculate the amount of various raw materials according to the ratio of the dephosphorization agent components described in the first aspect, put them into the raw material bin after weighing, and then screen them;

[0017] S2, sending the screened raw materials in S1 into a mixing silo, mixing them in the mixing silo for 3-5 minutes, adding 2-5%, preferably 3% of the total weight of the raw materials, adding 3-6%, preferably 4% of water glass, and then continuing to mix for 5-10 minutes;

[0018] S3, send the material mixed evenly in S2 into a briquetting machine, and press it to obtain finished dephosphorization agent balls for converter.

[0019] Furthermore, in step S2, the binder is an organic binder, which comprises, by mass percentage, 12-17% cellulose, 50-60% corn starch, 20-30% lignin and 2-7% modifier.

[0020] Furthermore, in step S3, the diameter of the ball press roller is 400 mm, the width is 400 mm, the reducer power is 9 KW, the rotation speed is about 10 rpm, the designed output is 5 t / h, and the pressure of the ball press is 40 t.

[0021] Furthermore, the particle size of the dephosphorization agent finished ball is 30-40 mm, and the density is 2500-3500 kg / m 3 , the compressive strength of a single finished ball is ≥1000N.

[0022] The third aspect of the present invention provides a method for using the low-cost dephosphorization agent described in the first aspect, the method comprising: controlling the amount of dephosphorization agent added at 15-18 kg / ton of steel according to the temperature of the molten iron or molten steel and the Si content in the converter, wherein when the dephosphorization agent is added, the temperature of the molten iron or molten steel is ≥1380°C and the Si content is ≥0.35%.

[0023] The present invention provides a low-cost dephosphorization agent and a preparation method and application thereof, which have the following beneficial effects:

[0024] 1. All raw materials use solid waste in the factory or materials with low utilization value. The cost of dephosphorization agent raw materials is low. The combined use of several solid wastes does not affect the overall dephosphorization effect, and can achieve the dephosphorization effect of commercial dephosphorization agents.

[0025] 2. Rational use of solid waste resources within the factory is green and environmentally friendly, which helps avoid secondary environmental pollution.

[0026] 3. Reasonable use of Na2O, Al2O3, MgO and other components in the converter refining dust removal ash can help reduce the slag melting point, achieve rapid slag formation, and improve the dephosphorization effect.

[0027] 4. The dephosphorization agent pressing process is simple, and most of the equipment is renovated and reused, which greatly reduces the equipment investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A dephosphorization agent pressing process flow chart or a dephosphorization agent preparation system provided in an embodiment of the present invention; wherein, 1-raw material bin, 2-conveyor, 3-vibrating screen, 4-mixing bin, 5-binder barrel, 6-ball press, 7-finished product bin, 8-packing bag. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. The process parameters of the following embodiments that do not specify specific conditions are usually based on conventional conditions.

[0031] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0032] According to a first aspect of the present invention, a low-cost dephosphorization agent is provided, wherein the components of the dephosphorization agent include, by mass percentage: Fe3O4 16-22wt%, FeO 8-13wt%, Fe2O3 4-8wt%, CaO 46-53wt%, Na2O≤4wt%, MgO≤3wt%, Al2O3≤3wt%, SiO2≤10wt%, S<0.1wt%, P<0.05wt%;

[0033] The dephosphorization agent pressing raw materials include a fixing agent, an oxidizing agent and a flux;

[0034] The fixing agent is lime powder used for steelmaking desulfurization, and its main component is CaO;

[0035] The oxidant is the surface iron oxide scale of the rolled steel billet, and its main components are Fe3O4, Fe2O3 and FeO;

[0036] The flux is converter refining dust, and its main components are CaO, Na2O, MgO and Al2O3.

[0037] The raw materials of the dephosphorizing agent used in the present invention are all solid waste from the factory area or materials with low utilization value, and the raw material cost is low and easy to obtain. The lime powder (such as lime powder below 200 mesh) used has low activity and low reuse value for desulfurization. When used here, its main component CaO can combine with oxidized P2O5 to form a stable composite compound CaO﹒P2O5; iron scale is mainly produced by surface oxidation and shedding of steel billets during rolling. Due to the limitation of raw materials, TFe here exists in the form of a mixture of Fe3O4, Fe2O3 and FeO, wherein the mass percentage of Fe2O3 is 13-22wt%, the mass percentage of FeO is 25-35wt%, and the mass percentage of Fe3O4 is 50-62wt%. Fe3O4, Fe2O3 and FeO are used as oxidants of dephosphorization agents. Their main function is to supply oxygen and oxidize phosphorus in molten iron into P2O5. Converter refining dust is a solid waste material collected and treated by dust removal equipment during the steel smelting process. During the steel smelting process, due to the effects of high temperature, high pressure, high speed and other factors, a large amount of smoke, dust and other waste gases will be generated. These waste gases contain metal elements such as iron, potassium, sodium, magnesium, chromium, nickel, vanadium and non-metallic elements such as calcium, silicon and aluminum. After these waste gases are treated by dust removal equipment, dust ash will be formed. The presence of Na2O, MgO and Al2O3 components helps to reduce the slag melting point and improve the flowability of dephosphorization slag, while stimulating the dephosphorization reaction and enhancing the dephosphorization effect.

[0038] As an optional implementation of a low-cost dephosphorization agent of the present invention, the CaO content in the lime undersize powder for steelmaking desulfurization is 75-90wt% and the particle size is less than 3mm.

[0039] As an optional implementation of a low-cost dephosphorization agent of the present invention, the contents of Fe3O4, Fe2O3 and FeO in the surface oxide scale of the rolled steel billet are 50-62wt%, 13-22wt% and 25-35wt% respectively.

[0040] As an optional implementation of a low-cost dephosphorization agent of the present invention, the contents of Na2O and MgO in the converter refining dust removal ash are 15-23wt%, 8-15wt%, and 45-53wt% respectively; and the particle sizes are 5-30μm respectively.

[0041] As an optional implementation of a low-cost dephosphorization agent of the present invention, the preparation method of the dephosphorization agent includes raw material weighing, batching, mixing and pressing processes.

[0042] According to a second aspect of the present invention, the present invention provides a method for preparing the low-cost dephosphorization agent provided in the first aspect, comprising the following steps:

[0043] S1. Calculate the amount of various raw materials according to the ratio of the dephosphorization agent components described in the first aspect, put them into the raw material bin after weighing, and then screen them;

[0044] S2, sending the screened raw materials in S1 into a mixing silo, mixing them in the mixing silo for 3-5 minutes, adding 2-5%, preferably 3% of the total weight of the raw materials, adding 3-6%, preferably 4% of water glass, and then continuing to mix for 5-10 minutes;

[0045] S3, send the material mixed evenly in S2 into a briquetting machine, and press it to obtain finished dephosphorization agent balls for converter.

[0046] The preparation of the dephosphorization agent of the present invention can be completed by using the following preparation system, see Figure 1 The system includes: a raw material bin 1, a conveyor 2, a vibrating screen 3, a mixing bin 4, a binder barrel 5, a ball press 6, a finished product bin 7, and a packing bag 8. The discharge port of the raw material bin 1 is connected to the feed port of the conveyor 2, the discharge port of the conveyor 2 is connected to the feed port of the vibrating screen 3, the discharge port of the vibrating screen 3 is connected to the feed port of the belt S1, the feeding position of the belt S1 discharge port is connected to the feed port of the mixing bin 4, the binder barrel 5 material is added from the feed port of the mixing bin 4, the discharge port of the mixing bin 4 is connected to the feed port of the belt S2, the discharge port of the belt S2 is connected to the feed port of the ball press 6, the discharge port of the ball press 6 is connected to the feed port of the belt S3, the discharge port of the belt S3 is connected to the feed port of the finished product bin 7, the discharge port of the finished product bin 7 is connected to the feed port of the belt S4, and the discharge port of the belt S4 is connected to the packing bag 8.

[0047] During operation, the raw materials in the raw material bin 1 are sent to the vibrating screen 3 via the conveyor 2, and the screened raw materials are then sent to the mixing bin 4 via the belt S1 for mixing, the binder in the binder barrel 5 is added to the mixing bin 4, mixed with the raw materials in the mixing bin 4, and then sent to the ball press 6 via the belt S2 for ball making, the finished dephosphorization agent balls enter the finished product bin 7 via the belt S3, and then sent to the packaging bag 8 via the belt S4.

[0048] In the preparation method S1 of a low-cost dephosphorization agent of the present invention, the purpose of screening is to screen out ironware and debris through screening, such as screening out debris with relatively large sizes through a vibrating screen, the vibrating screen is a single-layer screen with bars, and the spacing between the bars is 16 mm; the raw materials can be weighed by an overhead crane electronic hook scale, such as a 5t electronic hook scale, and the ground remote control operation can be carried out, which greatly reduces the investment cost of traditional belt weighing system equipment.

[0049] The specific dosage of the three raw materials can be calculated according to the set composition ratio of the dephosphorization agent.

[0050] In step S2, the binder can be a conventional binder that plays a bonding role, and an organic binder can be further selected. Considering the role of each component in the mixing and pressing process, the binder preferably includes, by mass percentage, 12-17% cellulose, 50-60% corn starch, 20-30% lignin and 2-7% modifier. The binder is produced by Shandong Dafu Adhesive Co., Ltd. and the model is NHJ-Y-70-100.

[0051] As an optional implementation of the method for preparing a low-cost dephosphorization agent of the present invention, in step S3, the roller diameter of the ball press is 400 mm, the width is 400 mm, the reducer power is 9 KW, the speed is about 10 rpm, the designed output is 5 t / h, and the pressure of the ball press is 40 t.

[0052] The present invention adds 2-5%, preferably 3% of the total weight of the raw materials in the mixing process in the mixing bin, and adds 3-6%, preferably 4% of the total weight of the raw materials. Water glass is added to avoid the reaction between conventional water and CaO in the raw materials to generate Ca(OH)2, which causes the effective components to fail. The binder is produced by Shandong Dafu Adhesive Co., Ltd., and after it encounters water glass during the pressing process, it generates high bonding force through infiltration and penetration to bond the dust particles together.

[0053] As an optional embodiment of the method for preparing a low-cost dephosphorization agent of the present invention, the particle size of the finished dephosphorization agent ball is 30-40 mm, and the density is 2500-3500 kg / m 3 , the compressive strength of a single finished ball is ≥1000N.

[0054] The finished dephosphorization agent balls are packed in waterproof and moisture-proof bags to avoid powdering.

[0055] According to the third aspect of the present invention, the present invention also provides a method for using the above-mentioned dephosphorization agent. The specific method is to transport the finished balls into a pit bucket by car, and load them into the high-level silo of the converter. When the temperature of the molten iron or molten steel is ≥1380°C and the Si content is ≥0.35%, the amount of dephosphorization agent added is controlled at 15-18kg / ton of steel.

[0056] The present invention is further described in detail below in conjunction with specific examples and comparative examples. The adhesive used in the following examples is an adhesive of model NHJ-Y-70-100 produced by Shandong Dafu Adhesive Co., Ltd.

[0057] Example 1

[0058] (1) Prepare a dephosphorizing agent, the preparation method is as follows:

[0059] S1, overhead crane electronic hook scale, take 49 parts of lime powder for steelmaking desulfurization, 32 parts of iron oxide scale, and 19 parts of converter refining dust, put them into the raw material warehouse, and send them to the vibrating screen for screening through the conveyor to screen out ironware and debris;

[0060] S2, a total of 1000 kg of the screened raw materials in S1 are sent to a mixing silo, and mixed in the mixing silo for 3-5 minutes, during which 30 kg of a binder accounting for 3% of the total weight of the raw materials and 40 kg of water glass accounting for 4% of the total weight of the raw materials are added, and the mixing is continued for 5-10 minutes;

[0061] S3, the material after S2 is evenly mixed is sent into a ball press, wherein the ball press has a roller diameter of 400mm, a width of 400mm, a reducer power of 9KW, a rotation speed of about 10rpm, a designed output of 5t / h, a pressure of the ball press of 40t, and finally the finished dephosphorization agent balls for converter are obtained by pressing. The percentage content of each component in the dephosphorization agent prepared by the present invention is Fe3O4 18wt%, FeO 9wt%, Fe2O3 5wt%, CaO 47wt%, Na2O3.8wt%, MgO2.8wt%, Al2O32.5wt%, SiO29.7wt%, S0.08wt%, P0.03wt%, and other components that do not affect the dephosphorization effect are 2.09wt%.

[0062] (2) Application in steelmaking converter blowing

[0063] The dephosphorization agent prepared above is loaded into the high-level silo of the steelmaking converter via a car or a pit bucket for standby use.

[0064] The temperature of the molten iron in the ladle was detected to be 1380℃, and the Si content was 0.35%. The molten iron in the ladle was poured into the converter and oxygen blowing was started. After 1 minute, dephosphorization agent was added from the high-level silo at a rate of 200kg per batch and added every 20 seconds. The total amount of dephosphorization agent added was controlled at 18kg per ton of steel. The addition of dephosphorization agent was completed in the 4th minute. At this time, it was in the early stage of blowing and splashing was not obvious.

[0065] Example 2

[0066] (1) Prepare a dephosphorizing agent, the preparation method is as follows:

[0067] S1, overhead crane electronic hook scale, take 50 parts of lime powder for steelmaking desulfurization, 33 parts of iron oxide scale, and 17 parts of converter refining dust, put them into the raw material warehouse, and send them to the vibrating screen for screening through the conveyor to screen out ironware and debris;

[0068] S2, a total of 1000 kg of the screened raw materials in S1 are sent to a mixing silo, and mixed in the mixing silo for 3-5 minutes, during which 30 kg of a binder accounting for 3% of the total weight of the raw materials and 40 kg of water glass accounting for 4% of the total weight of the raw materials are added, and the mixing is continued for 5-10 minutes;

[0069] S3, the material after S2 is evenly mixed is sent into a ball press, wherein the ball press roller diameter is 400mm, the width is 400mm, the reducer power is 9KW, the speed is about 10rpm, the designed output is 5t / h, the pressure of the ball press is 40t, and finally the finished dephosphorization agent balls for converter are obtained by pressing. The percentage content of each component in the dephosphorization agent prepared by the present invention is Fe3O420wt%, FeO10wt%, Fe2O3 7wt%, CaO 49wt%, Na2O2.7wt%, MgO1.8wt%, Al2O32.1wt%, SiO25.81wt%, S0.07wt%, P0.02wt%, and other components that do not affect the dephosphorization effect are 1.5%.

[0070] (2) Application in steelmaking converter blowing

[0071] The dephosphorization agent prepared above is loaded into the high-level silo of the steelmaking converter via a car or a pit bucket for standby use.

[0072] The temperature of the molten iron in the ladle was detected to be 1390℃, and the Si content was 0.37%. The molten iron in the ladle was poured into the converter and oxygen blowing was started. After 1 minute, dephosphorization agent was added from the high-level silo at a rate of 200kg per batch and added every 20 seconds. The total amount of dephosphorization agent added was controlled at 18kg per ton of steel. The addition of dephosphorization agent was completed in the 4th minute. At this time, it was in the early stage of blowing and splashing was not obvious.

[0073] Example 3

[0074] (1) Prepare a dephosphorizing agent, the preparation method is as follows:

[0075] S1, overhead crane electronic hook scale, take 52 parts of lime powder for steelmaking desulfurization, 34 parts of iron oxide scale, and 14 parts of converter refining dust, mix them into the raw material warehouse, and send them to the vibrating screen for screening through the conveyor to screen out ironware and debris;

[0076] S2, a total of 1000 kg of the screened raw materials in S1 are sent to a mixing silo, and mixed in the mixing silo for 3-5 minutes, during which 30 kg of a binder accounting for 3% of the total weight of the raw materials and 40 kg of water glass accounting for 4% of the total weight of the raw materials are added, and the mixing is continued for 5-10 minutes;

[0077] S3, the material after S2 is evenly mixed is sent into a ball press, wherein the ball press roller diameter is 400mm, the width is 400mm, the reducer power is 9KW, the speed is about 10rpm, the designed output is 5t / h, the pressure of the ball press is 40t, and finally the finished dephosphorization agent balls for converter are obtained by pressing. The percentage content of each component in the dephosphorization agent prepared by the present invention is Fe3O4 22wt%, FeO12wt%, Fe2O3 8wt%, CaO51wt%, Na2O1.7wt%, MgO1.1wt%, Al2O30.8wt%, SiO21.9wt%, S0.04wt%, P0.02wt%, and other components that do not affect the dephosphorization effect are 1.44%.

[0078] (2) Application in steelmaking converter blowing

[0079] The dephosphorization agent prepared above is loaded into the high-level silo of the steelmaking converter via a car or a pit bucket for standby use.

[0080] It was detected that the temperature of the molten iron in the converter was 1387℃ and the Si content was 0.38%. The molten iron from the ladle was poured into the converter and oxygen blowing began. After 1 minute, dephosphorization agent was added from the high-level silo at a rate of 200kg per batch and added every 20 seconds. The total amount of dephosphorization agent added was controlled at 18kg per ton of steel. The dephosphorization agent was added in the 4th minute. At this time, it was in the early stage of blowing and splashing was not obvious.

[0081] Comparative Example 1

[0082] (1) Only the company's internally sintered ore is used as a dephosphorization agent, and the percentage of its components is TFe 54-57wt%, FeO 8-11wt%, CaO 9-11.5wt%, MgO 1.8-2.2wt%, Al2O3 2.3-2.8wt%, SiO2 5-6wt%, and P < 0.08wt%.

[0083] (2) Application in steelmaking converter blowing

[0084] The required sintered ore is loaded into the high-level silo of the steelmaking converter via trucks and pit buckets for standby use.

[0085] The molten iron temperature of the ladle was detected to be 1370℃, and the Si content was 0.32%. The molten iron in the ladle was poured into the converter and started blowing. After 3 minutes, sintered ore was added from the high-level silo, and 150kg was added every 30 seconds, with a total amount of 15kg per ton of steel. The dephosphorization agent was added in the 7th minute, which was in the middle of blowing, and the splashing phenomenon was obvious during the period. Its addition method, addition amount and addition time are the best choices for dephosphorization of this kind of sintered ore.

[0086] Comparative Example 2

[0087] (1) Use of external dephosphorization agent

[0088] The purchased finished dephosphorization agent has the following components in percentage: TFe 48-55wt%, CaO 3-5wt%, MgO 0.8-1.5wt%, Al2O3 17-22wt%, SiO2 5-7wt%.

[0089] (2) Application in steelmaking converter blowing

[0090] The purchased dephosphorization agent is loaded from the warehouse to the high-level silo of the steelmaking converter via trucks and pit buckets for standby use.

[0091] When it is detected that the molten iron temperature in the ladle is 1375℃ and the Si content is 0.32%, pour the molten iron in the ladle into the converter. According to the manufacturer's instructions, add 400kg before blowing, do not add when starting blowing, and add another 600-700kg in two batches after the 4th minute in the middle of blowing. The total amount is controlled at 10kg per ton of steel. There is a certain amount of splashing during the period. The addition method and amount are operated according to the instructions for use of the dephosphorization agent.

[0092] The specific effects of the dephosphorization agent finished balls prepared in the examples and comparative examples in the application of steel dephosphorization are shown in Table 1:

[0093] Table 1

[0094]

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-cost dephosphorization agent, characterized in that: In terms of mass percentage, the components of the dephosphorizing agent include: Fe3O4 16-22wt%, FeO 8-13wt%, Fe2O3 4-8wt%, CaO 46-53wt%, Na2O≤4wt%, MgO≤3wt%, Al2O3≤3wt%, SiO2≤10wt%, S<0.1wt%, and P<0.05wt%; The dephosphorization agent raw materials include a fixing agent, an oxidizing agent and a flux; The fixing agent is lime powder used for steelmaking desulfurization, and its main component is CaO; The oxidant is the surface iron oxide scale of the rolled steel billet, and its main components are Fe3O4, Fe2O3 and FeO; The flux is converter refining dust, and its main components are CaO, Na2O, MgO and Al2O3.

2. The low-cost dephosphorization agent according to claim 1, characterized in that: The content of CaO in the lime undersize powder for steelmaking desulfurization is 75-90wt%, and the particle size is less than 3mm.

3. The low-cost dephosphorization agent according to claim 1, characterized in that: The contents of Fe3O4, Fe2O3 and FeO in the surface iron oxide scale of the rolled steel billet are 50-62wt%, 13-22wt% and 25-35wt% respectively.

4. The low-cost dephosphorization agent according to claim 1, characterized in that: The contents of Na2O and MgO in the converter refining dust removal ash are 15-23wt%, 8-15wt%, and 45-53wt% respectively; and the particle sizes are 5-30μm respectively.

5. The low-cost dephosphorization agent according to claim 1, characterized in that: The preparation method of the dephosphorization agent comprises the processes of raw material weighing, batching, mixing and pressing.

6. A method for preparing the low-cost dephosphorization agent according to any one of claims 1 to 5, characterized in that: The steps include: S1. Calculate the amount of various raw materials according to the ratio of the dephosphorization agent components according to any one of claims 1 to 5, put them into the raw material warehouse after weighing, and then screen them; S2, sending the screened raw materials in S1 into a mixing silo, mixing them in the mixing silo for 3-5 minutes, adding 2-5%, preferably 3% of the total weight of the raw materials, adding 3-6%, preferably 4% of water glass, and then continuing to mix for 5-10 minutes; S3, send the material mixed evenly in S2 into a briquetting machine, and press it to obtain finished dephosphorization agent balls for converter.

7. The method for preparing a low-cost dephosphorization agent according to claim 6, characterized in that: In step S2, the binder is an organic binder, which comprises, by mass percentage, 12-17% cellulose, 50-60% corn starch, 20-30% lignin and 2-7% modifier.

8. The method for preparing a low-cost dephosphorization agent according to claim 6, characterized in that: In step S3, the diameter of the ball press roller is 400 mm, the width is 400 mm, the reducer power is 9 KW, the rotation speed is about 10 rpm, the designed output is 5 t / h, and the pressure of the ball press is 40 t.

9. The method for preparing a low-cost dephosphorization agent according to any one of claims 6 to 8, characterized in that: The particle size of the dephosphorization agent finished ball is 30-40mm, and the density is 2500-3500kg / m 3 , the compressive strength of a single finished ball is ≥1000N.

10. A method for using the low-cost dephosphorization agent as claimed in claim 1, characterized in that: The method of use comprises: controlling the amount of dephosphorizing agent added at 15-18 kg / ton steel according to the temperature of molten iron or molten steel and the Si content in the converter, wherein when the dephosphorizing agent is added, the temperature of the molten iron or molten steel is ≥1380°C and the Si content is ≥0.35%.

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