CN102304606A - Slag former and slagging method for semisteel steelmaking - Google Patents

Abstract

The invention provides a slagging agent for semi-steel steelmaking and a slagging method for semi-steel steelmaking. The slagging agent includes 60%-75% of SiO ₂ , 10%-15% of CaO, 1%-3% of MgO, 7%-15% of FeO, 1%-3% of Fe ₂ O ₃ and Minor unavoidable impurities. The slagging method includes: using a slagging agent for semi-steel making, active lime and high-magnesium lime to make slagging, and properly controlling the timing and amount of adding slagging materials. Using the slag-forming agent for semi-steel and steelmaking of the present invention and the slagging method for semi-steel steelmaking to smelt semi-steel can overcome the problems of slow slagging speed and low dephosphorization rate during semi-steel smelting, and can effectively shorten the The initial slag formation time and pure oxygen blowing time are improved, and the dephosphorization rate of molten steel at the end of the converter is improved.

Description

Slagging agent for semi-steel steelmaking and slagging method for semi-steel steelmaking

technical field

The invention relates to the technical field of steelmaking, more specifically, to a slag-forming agent for semi-steel steelmaking and a slagging method for semi-steel steelmaking.

Background technique

When vanadium-titanium-magnetite resources are used for smelting to produce steel, the main raw material for converter steelmaking is semi-steel after vanadium extraction in a dedicated converter. Usually, the molten steel obtained after vanadium-containing molten iron is desulfurized and vanadium-extracted is called semi-steel. In the semi-steel obtained after vanadium-containing molten iron is desulfurized and vanadium is extracted, the mass percentage of carbon is 3.4% to 4.0%, the content of exothermic slagging elements such as silicon and manganese are all traces, and the mass percentage of sulfur is controlled at 0.015% Within, the mass percentage content of phosphorus element is 0.060%-0.080%. Therefore, semi-steel steelmaking has the characteristics of less acidic slagging substances, single slag system components and insufficient heat in the blowing process, resulting in a long time for the formation of initial slag under semi-steel steelmaking conditions and a low dephosphorization rate. The problem of insufficient heat can be solved by adding a temperature raising agent, but the problems of slow slagging, low dephosphorization rate and long smelting time have always been prominent problems in semi-steel making.

In the prior art, although various slagging agents for converter steelmaking and their manufacturing methods are disclosed, basically none of them can solve the above-mentioned technical problems.

Chinese Patent Application No. 1241637 published on January 19, 2000 discloses a composite slagging agent, which mainly contains (weight percent) steelmaking sludge 10% to 70%, lightly burned magnesium powder 30% %~90%. In addition, it may also contain 1% to 8% of silicon micropowder, 6% to 8% of light calcium carbonate and other substances whose content is greater than 0% and less than or equal to 5%. The slagging agent has the advantages of fast melting, high utilization rate, protection of furnace lining and recycling of steelmaking sludge. However, the patent does not explain its specific slagging method and application effect; and from the composition of the composite slagging agent, it can be seen that its main component is steelmaking sludge balls. Since steelmaking sludge balls have a strong cooling effect, In addition, there is already a problem of insufficient heat source in semi-steel making, so adding too much sludge balls for slagging will definitely aggravate the problem of insufficient heat source in semi-steel making. Therefore, this slagging agent is not suitable for semi-steel smelting.

Chinese Patent Application No. 1278012 published on December 27, 2000 discloses a method for producing a steelmaking slagging agent from steelmaking converter sludge. The steelmaking composite slag produced by the method has the characteristics of recycling converter steelmaking sludge, dolomite powder and other industrial wastes, reducing steelmaking costs and the like. However, this application mainly expounds the production method of steelmaking slagging agent, and does not involve the use method and effect of use, and considering that the temperature loss of semi-steel is too large to use sludge balls to make slag, therefore, the method of this application makes The obtained steelmaking slagging agent is not suitable for semi-steel smelting.

The document titled "Experimental Research on the Forming of Slagging Agents Prepared by Using Steel Slag" published in the journal "Steelmaking" on October 5, 2009, discloses a method of preparing slag-forming agents from steel slags using the cold-pressed ball forming process. Forming method, and the influence of the amount of binder, the amount of water and the forming pressure on the mechanical properties of the briquetting was investigated. The slagging agent also has the characteristics of low melting point, fast slagging and strong ability to remove harmful substances in steel. However, the main component of the slagging agent produced in this document is CaO, and the research focuses on the various properties of the slagging agent, and there is no industrial verification of the use effect of the slagging agent.

On November 30, 2000, the document titled "Development and Application of Panzhihua Steelmaking Composite Slagging Agent" published in the journal "Iron and Steel Vanadium Titanium" disclosed a kind of slagging agent designed according to the characteristics of semi-steelmaking. slagging agent, and verified by comparative tests that the main components of the composite slagging agent are (weight percent) SiO ₂ (47.30%), Al ₂ O ₃ (7.58%), CaO (11.66%), MnO (7.67%) when the initial stage The slag formation time is 4.97min, which can shorten the initial slag formation time by 0.73min compared with the comparative test furnace. At the same time, the use of this slagging agent has better dephosphorization and desulfurization ability. However, judging from the test results of the composite slagging agent in this document, the initial slag formation time is relatively long, and the free calcium oxide content in the slag is still relatively high, indicating that the initial slag is not melted well, and there is still room for improving the metallurgical effect.

Contents of the invention

In view of the deficiencies in the prior art, one purpose of the present invention is to solve one or more problems in the above prior art. The invention provides a slagging agent for semi-steel making and a slag-making method for semi-steel making. Using the invention can shorten the initial slag formation time and pure oxygen blowing time, and can effectively solve the problem of slag formation during semi-steel smelting slow and low dephosphorization rate, and improve the dephosphorization efficiency of semi-steel smelting.

One aspect of the present invention provides a slagging agent for semi-steel making. The slagging agent comprises 60%-75% of SiO ₂ , 10%-15% of CaO, 1%-3% of MgO, 7%-15% of FeO, 1%-3% of Fe ₂ O ₃ and a small amount of unavoidable impurities. The particle size composition of the slagging agent in terms of weight percentage may be: more than 95% of the slagging agent has a particle size of 15 mm to 35 mm, and less than 5% of the particle size is less than 5 mm.

Another aspect of the present invention provides a slagging method for semi-steel making. The slagging method includes: using the above-mentioned slagging agent for semi-steelmaking, active lime and high-magnesium lime when the converter smelts semi-steel, and using the slagging agent once after blowing starts The active lime and high-magnesia lime are added into the converter in two batches, wherein the first batch of active lime and high-magnesia lime is added to the converter at the same time as the slagging agent.

Another aspect of the present invention provides a slagging method for semi-steel making. The slag-making method includes: using the above-mentioned slag-forming agent for semi-steelmaking, active lime and high-magnesium lime to carry out slagging when the converter smelts semi-steel, and after the blowing starts, the slag-forming agent, The slagging raw materials composed of active lime and high magnesium lime are added to the converter in two batches.

Compared with the prior art, the beneficial effect of the present invention is that it can overcome the problems of slow slagging and low dephosphorization rate when smelting semi-steel with vanadium-containing molten iron after desulfurization and vanadium extraction, and can effectively shorten the initial stage. The slag formation time and pure oxygen blowing time are improved, and the dephosphorization rate of molten steel at the end of the converter is improved.

Detailed ways

Hereinafter, the slagging agent for semi-steel and steelmaking and the slagging method for semi-steel and steelmaking of the present invention will be described in detail with reference to exemplary embodiments. In the present invention, if there is no exception, all solid and liquid substances (for example, slagging agent, active lime, high magnesium lime, sludge balls for steelmaking, and sulfur and phosphorus elements in steel or molten steel, etc.) All percentages are by weight, and all percentages of gaseous substances (eg, oxygen) are by volume.

According to the first aspect of the present invention, the slagging agent for semi-steel making steel includes 60% to 75% of SiO ₂ , 10% to 15% of CaO, 1% to 3% of MgO, 7% to 15% FeO, 1% to 3% Fe ₂ O ₃ and a small amount of unavoidable impurities. The particle size composition of the slagging agent in terms of weight percentage may be: more than 95% of the slagging agent has a particle size of 15 mm to 35 mm, and less than 5% of the particle size is less than 5 mm. The slagging agent of the present invention contains relatively high SiO ₂ , because the silicon content of semi-steel is a trace, a large amount of SiO ₂ cannot be formed during the silicon oxidation period to promote slagging, and the relatively high SiO ₂ in the slagging agent can be combined with CaO forms silicate with a lower melting point, which accelerates the dissolution of lime and promotes slag melting. At the same time, about 15% iron oxide contained in the slagging agent can also accelerate the dissolution of lime. The two main components together promote the melting of slag and shorten the initial slag formation time. If the SiO ₂ content in the slagging agent is too high, the initial slag alkalinity will be too low, or consume more lime to achieve a suitable alkalinity; if the SiO ₂ content in the slagging agent is too low, there will be no obvious promotion The role of slag. If the content of iron oxides (for example, steelmaking sludge balls) is too high, the temperature drop of the semi-steel will be too large, and if the content of iron oxides is too low, it is not conducive to slag melting. The main reason to keep the particle size of the slagging agent between 15mm and 35mm is to melt it faster when it is added to the converter. If the particle size is too fine or powdery, the dust will be too large during the addition process, and it will be added to the converter at the same time. Finally, a layer of lime powder may be formed on the molten steel surface or form a lime slag, which will affect the melting of lime and prolong the slagging time; if the particle size of the slagging agent is greater than 35mm, its melting speed will decrease.

According to the second aspect of the present invention, the slagging method for semi-steelmaking steelmaking includes: when the converter smelts semi-steel, adopt the above-mentioned semi-steelmaking slagging agent, active lime and high-magnesium lime to carry out slagging, After the smelting starts, the slagging agent is added to the converter all at once, and the active lime and high-magnesia lime are added to the converter in two batches, wherein the first batch of active lime and high-magnesia lime is added at the same time as the slagging agent Converter. The slagging method for semi-steel making steelmaking according to another aspect of the present invention is preferably mainly suitable for the production of steel grades that do not require high phosphorus and sulfur content in molten steel (for example, less than 0.025%).

According to the third aspect of the present invention, the slagging method of semi-steelmaking steelmaking includes: when the converter smelts semi-steel, adopt the above-mentioned semi-steelmaking slagging agent, active lime and high-magnesium lime to carry out slagging, After the smelting starts, the slagging raw materials composed of the slagging agent, active lime and high-magnesia lime are added to the converter in two batches. The slag-making method for semi-steel steelmaking according to the third aspect of the present invention is preferably mainly suitable for the process of smelting low-phosphorus and low-sulfur steels with a large amount of slag. For example, the slag-making method can be used to produce molten steel Steel grades with relatively low phosphorus and sulfur content (eg, less than 0.01%) are required.

In an exemplary embodiment of the slagging method for semi-steel making according to the second or third aspect of the present invention, the total amount of the slagging agent added may conform to the following formula:

W1=(W2×η ₁ +W3×η ₄ )/[R(η ₂ -η ₃ )]

Among them, W1 is the weight of slagging agent added per ton of semi-steel, and the unit is Kg/ton of semi-steel;

W2 is the weight of active lime added per ton of semi-steel, in Kg/ton of semi-steel;

W3 is the weight of high magnesium lime added per ton of semi-steel, in Kg/ton of semi-steel;

R is the required basicity of slag at the end of converter blowing, and R is 3.5-4.5;

η ₁ is the mass percent of CaO in the active lime that adds, and unit is %;

η ₂ is the mass percentage of _SiO in the slagging agent that adds, unit is %;

η ₃ is the mass percent of CaO in the slagging agent that adds, unit is %;

η ₄ is the mass percentage of CaO in the high magnesium lime added, and the unit is %.

In the present invention, the basicity is set within the range of 3.5 to 4.5, mainly to ensure that the slag has a certain viscosity while the slag has better dephosphorization and desulfurization efficiency, so as to meet the needs of slag splashing to protect the furnace. If the alkalinity is too high, the viscosity of the slag will be high. When the slag is splashed, the slag cannot splash well on the furnace lining to protect the furnace lining. The slag on the surface cannot be well adhered to the furnace lining, and it also cannot play the role of slag splashing to protect the furnace.

In an exemplary embodiment of the slagging method for semi-steel making and steelmaking according to the second aspect or the third aspect of the present invention, the total amount of active lime added may be 25-50Kg/ton of steel, and the active lime It may contain more than 85% CaO by weight percentage; the total amount of the high-magnesia lime added may be 15-25Kg/ton of steel, and the high-magnesia lime may contain 45%-55% CaO and 30% to 50% MgO.

In an exemplary embodiment of the slagging method for semi-steelmaking steelmaking according to the second aspect of the present invention, the amount of the first batch of active lime added may account for 70% to 80% of the total amount of active lime added, The amount of the first batch of high-magnesia lime added can account for 65% to 75% of the total amount of high-magnesia lime added, and the basicity of the slag can be controlled between 2 and 2.5, and when the oxygen blowing amount of semi-steel smelting When 65% to 75% of the total amount of oxygen blown in during the whole semi-steel smelting process is reached, the second batch of active lime and high-magnesia lime can be added. Here, the basicity of the slag is controlled between 2 and 2.5, mainly because the dephosphorization efficiency is the best in this basicity range. When the basicity of the slag is greater than 2.5 or less than 2, the dephosphorization efficiency decreases. Here, the reason why the second batch of activated lime and high-magnesium lime is added when the amount of oxygen blown in semi-steel smelting reaches 65% to 75% of the total amount of oxygen blown in the entire semi-steel smelting process is because the slag in the early stage has already melted. and the best dephosphorization effect has been achieved, adding the second batch of slag at this time can further promote dephosphorization and inhibit rephosphorization.

In an exemplary embodiment of the slagging method for semi-steelmaking steelmaking according to the third aspect of the present invention, the amount of the slagging agent added in the first batch can account for 60-60% of the total amount of the slagging agent added. 70%, the amount of active lime added in the first batch can account for 65% to 75% of the total amount of active lime added, and the amount of high magnesium lime added in the first batch can account for 50% to 50% of the total amount of high magnesium lime added 60%, and when the amount of oxygen blown in semi-steel smelting reaches 60%-70% of the total amount of oxygen blown in the whole semi-steel smelting process, the second batch of slagging raw materials can be added.

In an exemplary embodiment of the slagging method for semi-steel making according to the second or third aspect of the present invention, the slagging method further includes: When adding the first batch of slagging raw materials, add 4-8Kg/ton of steel-making sludge balls to the converter within 2 minutes of blowing, and the steel-making sludge balls contain 25wt%-40wt% by weight % iron oxide. Here, the sludge balls for steelmaking are commonly used coolants for converter steelmaking, but the difference is that the sludge balls for steelmaking used in the present invention contain a very high content of iron oxides. Preferably, the steelmaking sludge balls used in the present invention contain 11% to 20% of CaO, 5% to 10% of SiO ₂ , 5% to 10% of MgO, 25% to 40% of Iron oxides, the rest are moisture and unavoidable impurities. In the slagging method of the present invention, adding sludge balls for steelmaking can reduce the temperature of the molten pool, slow down the carbon-oxygen reaction rate in the furnace, so that the temperature rise rate of the molten pool will not be too fast, and the molten pool will be in the low temperature zone ( 1400℃～1500℃) to maintain a longer residence time, which can further improve the effect of low temperature dephosphorization in the early stage.

In an exemplary embodiment of the slagging method for semi-steelmaking according to the second aspect or the third aspect of the present invention, the slagging method further includes adding a slagging agent into the converter to adjust the The slag adjustment operation of slag viscosity can reduce the amount of slag during tapping and ensure the requirement of slag viscosity for slag splash protection operation.

Hereinafter, the slagging agent for semi-steel making and the slagging method for semi-steel making steel of the present invention will be further described in combination with examples and comparative examples.

Example 1:

Use semi-steel after vanadium extraction to smelt 45# high-quality carbon structural steel, and the content of phosphorus and sulfur in molten steel is required to be lower than 0.025%. Mix 135t of semi-steel into a 120t converter for smelting and use the slagging method of semi-steel making steelmaking according to the second aspect for smelting.

The composition of the semi-steel in the furnace is: 3.5wt% of C, 0.042wt% of Mn, 0.088wt% of P, 0.015wt% of V, 0.009wt% of S, traces of Si, and the rest of Fe. The semi-steel temperature is 1335°C. A 5-hole oxygen lance is used for blowing, and the oxygen supply intensity is 3.1-4.0Nm ³ /t·min. Add all semi-steel steelmaking slag-forming agents and the first batch of active lime and high-magnesium lime at the same time of blowing, wherein, the addition of active lime (containing 88wt% CaO) is 20Kg/t _semi-steel , high-magnesium Lime (containing 45wt% CaO and 30wt% MgO) was added in an amount of 10kg/t _semi-steel . The amount of slagging agent used for semi-steel making is 8.26kg/t _{of semi-steel} , and its composition is: 60wt% SiO ₂ , 15wt% CaO, 3wt% MgO, 15wt% FeO, 3wt% Fe ₂ O ₃ and the balance of unavoidable impurities.

When the oxygen blowing amount reaches 65% of the total amount of oxygen blown in the whole semi-steel smelting process, add the second batch of slagging materials, wherein the addition of active lime (containing 88wt% CaO) is 8Kg/t _semi-steel , The addition amount of high magnesium lime (containing 45wt% CaO and 30wt% MgO) is 5kg/t _semi-steel . Then, the slag is adjusted and the steel is tapped, and the phosphorus content in the molten steel is 0.07% when the steel is tapped.

It is measured that the initial slag formation time is 3.01min, and the content of free calcium oxide in the final slag is 7.13wt%, which shows that the slag melting effect is good. And the pure oxygen blowing time is 11.62min, and the dephosphorization rate in the smelting process is 92.05%.

Example 2:

The P72LX steel is smelted using the vanadium-extracted semi-steel, and the phosphorus and sulfur content of molten steel are required to be lower than 0.01%. Mix 138t of semi-steel into a 120t converter for smelting and use the slagging method of semi-steel making steelmaking according to the third aspect for smelting.

The composition of the semi-steel in the furnace is: 3.46wt% of C, 0.038wt% of Mn, 0.076wt% of P, 0.012wt% of V, 0.003wt% of S, traces of Si, and the rest of Fe. The semi-steel temperature is 1328°C. A 5-hole oxygen lance is used for blowing, and the oxygen supply intensity is 3.1-4.0Nm ³ /t·min. The slagging material composed of slagging agent for semi-steel making, active lime and high magnesium lime is added to the converter in two batches. Add the first batch of slagging materials while blowing, wherein, the addition of active lime (containing 86wt% of CaO) is 35Kg/t _semi-steel , high magnesium lime (containing 55wt% of CaO and 50wt% of MgO) The addition amount is 10kg/t _semi-steel , the addition amount of slagging agent for semi-steel steelmaking is 9.76kg/t _semi-steel , and the composition of slagging agent for semi-steel steelmaking is: 75wt% SiO ₂ , 10wt% CaO , 1wt% of MgO, 7wt% of FeO and _1wt % of _Fe2O3 and the balance of unavoidable impurities.

When the oxygen blowing amount reaches 60% of the total amount of oxygen blown in the whole semi-steel smelting process, add the second batch of slagging materials, wherein the addition of active lime (containing 86wt% CaO) is 15Kg/t _semi-steel , The addition of high magnesium lime (containing 55wt% CaO and 50wt% MgO) is 10kg/t _semi-steel , semi-steel steelmaking slagging agent (its composition is the same as that of semi-steel steelmaking in the first batch in this embodiment) The same as the slagging agent) is added in an amount of 4.62kg/t _semi-steel . At the end of the smelting process, the viscosity of the slag is adjusted with a slag adjusting agent, and part of the slag is poured out. The phosphorus content in the end point molten steel is 0.005%, and the sulfur content is 0.005%.

It is measured that the initial slag formation time is 2.38min, the free calcium oxide content in the final slag is 6.85wt%, the pure oxygen blowing time is 11.48min, and the dephosphorization rate in the converter smelting process is 93.42%.

Example 3:

The semi-steel after vanadium extraction is used to smelt 50 high-quality carbon structural steel, and the phosphorus and sulfur content of molten steel are required to be lower than 0.025%. Mix 140t of semi-steel into a 120t converter for smelting and use the slagging method of semi-steel making steelmaking according to the second aspect for smelting.

The composition of the semi-steel in the furnace is: 3.63wt% of C, 0.048wt% of Mn, 0.068wt% of P, 0.018wt% of V, 0.0010wt% of S, traces of Si, and the rest of Fe. The semi-steel temperature is 1360°C. A 5-hole oxygen lance is used for blowing, and the oxygen supply intensity is 3.1-4.0Nm ³ /t·min. Add all semi-steel steelmaking slagging agents and the first batch of active lime and high-magnesium lime at the same time as the blowing is started, wherein the addition of active lime (containing 87wt% CaO) is 20Kg/t _semi-steel , high-magnesium Lime (containing 50wt% CaO and 40wt% MgO) was added in an amount of 15kg/t _semi-steel . The amount of slagging agent used for semi-steel making is 9.06kg/t _{of semi-steel} , and its composition is: 68wt% SiO ₂ , 13wt% CaO, 2wt% MgO, 11wt% FeO, 2wt% Fe ₂ O ₃ and the balance of unavoidable impurities.

After blowing for 1 minute, add 6Kg/t _semi-steel of sludge balls for steelmaking. This sludge ball for steelmaking contains 15% of CaO, 8% of SiO ₂ , 7% of MgO, 33% of iron oxide, and the balance of water and unavoidable impurities. When the oxygen blowing amount reaches 75% of the total amount of oxygen blown in the whole semi-steel smelting process, add the second batch of slagging materials, wherein the addition of active lime (containing 87wt% CaO) is 10Kg/t _semi-steel , The addition amount of high magnesium lime (containing 50wt% CaO and 40wt% MgO) is 5kg/t _semi-steel . Then, the slag is adjusted and the steel is tapped, and the phosphorus content in the molten steel is 0.05% when the steel is tapped.

It is measured that the initial slag formation time is 2.87min, and the content of free calcium oxide in the final slag is 7.05wt%, which shows that the slag melting effect is very good. And the pure oxygen blowing time is 11.79min, and the dephosphorization rate in the smelting process is 92.65%.

Comparative example 1:

Converter steelmaking is carried out according to the method of Example 1, the difference is that the converter slagging materials are all added to the converter at one time, and the composition and content of the slagging agent are different. A commonly used composite slagging agent is used, and its composition is: 49wt% SiO _2. 10wt% _of CaO, 4wt% of MgO, 7wt% of FeO, 7wt% of Fe2O3, 6wt% of _{Al2O3 , 3wt} % of C and the balance of moisture and unavoidable impurities. It was found that the initial slag formation time was 3.89min, and the free calcium oxide content in the terminal slag was 8.68wt%, indicating that the slag melting effect was not very good, the pure oxygen blowing time was 12.82min, and the dephosphorization rate in the smelting process was 88.39%.

Comparative example 2:

Carry out the converter steelmaking by the method for embodiment 2, difference is that the second batch of slag-forming materials blows 4min (that is, the oxygen blowing amount is about 30%～40% of the total amount of oxygen blown in the semi-steel steelmaking process ), and the composition of the slagging agent is different. The main components of the slagging agent are: 45wt% SiO ₂ , 13wt% CaO, 3wt% MgO, 10wt% FeO, 9wt% Fe ₂ O ₃ , 5wt% of Al ₂ O ₃ , 2wt% of C and the rest of moisture and unavoidable impurities. It was found that the initial slag formation time was 3.64min, and the free calcium oxide content in the terminal slag was 8.52wt%, indicating that the slag melting effect was not very good, the pure oxygen blowing time was 12.73min, and the dephosphorization rate in the smelting process was 89.67%.

Comparative example 3:

Converter steelmaking is carried out according to the method of Example 3, the difference is that the cooling material is changed from the sludge ball for steelmaking to steel scrap, and the composition of the slagging agent is different. The main component of the slagging agent is: 50wt% SiO ₂ , 12wt% CaO, 4wt% MgO, 11wt% FeO, 10wt% Fe ₂ O ₃ , 3wt% Al ₂ O ₃ , 3wt% C and the balance of moisture and unavoidable impurities. It was found that the initial slag formation time was 3.89min, and the free calcium oxide content in the final slag was 8.98wt%, indicating that the slag melting effect was not very good, the pure oxygen blowing time was 12.86min, and the dephosphorization rate during the smelting process was 86.43%.

It can be seen from the above examples and comparative examples that using the slagging agent and slagging method provided by the present invention can effectively shorten the initial slag formation time and pure oxygen blowing time, and can increase the dephosphorization rate of the converter.

In summary, adopting the slag-forming agent for semi-steel and steelmaking of the present invention and the slagging method for semi-steel steelmaking to carry out semi-steel steelmaking production can overcome the slow slagging speed and dephosphorization rate that exist during semi-steel smelting. It can effectively shorten the initial slag formation time and pure oxygen blowing time, and increase the dephosphorization rate of molten steel at the end of the converter.

Although the present invention has been described above in conjunction with some exemplary embodiments, it should be apparent to those skilled in the art that modifications and changes may be made to the above exemplary embodiments without departing from the spirit and scope defined by the claims.

Claims (10)

1. a semi-steel making slag former is characterized in that said slag former comprises 60%～75% SiO by weight percentage ₂, 10%～15% CaO, 1%～3% MgO, 7%～15% FeO, 1%～3% Fe ₂O ₃And a small amount of unavoidable impurities.

2. semi-steel making slag former as claimed in claim 1, it is characterized in that the size composition by weight percentage of said slag former is: granularity is accounting for more than 95% of 15mm～35mm, and granularity is less than 5% less than 5mm's.

3. the slagging method of a semi-steel making; It is characterized in that said slagging method comprises: when the converter smelting half steel, adopt semi-steel making as claimed in claim 1 or 2 to carry out slag making with slag former, quickened lime and high magnesium lime; After the blowing beginning, the disposable adding of said slag former is all added converter; And quickened lime and high magnesium lime are added converter in two batches; Wherein, the quickened lime of first adding and high magnesium lime and said slag former add converter simultaneously.

4. the slagging method of a semi-steel making; It is characterized in that said slagging method comprises: when the converter smelting half steel, adopt semi-steel making as claimed in claim 1 or 2 to carry out slag making, after the blowing beginning, will add converter in two batches by the slag making raw material that said slag former, quickened lime and high magnesium lime are formed with slag former, quickened lime and high magnesium lime.

5. like claim 3 or 4 described slagging methods, it is characterized in that the adding total amount of said slag former meets following formula:

W1＝(W2×η ₁+W3×η ₄)/[R(η ₂-η ₃)]

Wherein, W1 is the slag former weight that half steel per ton adds, and unit is a Kg/ ton half steel;

W2 is the weight of the quickened lime of half steel adding per ton, and unit is a Kg/ ton half steel;

W3 is the weight of the high magnesium lime of half steel adding per ton, and unit is a Kg/ ton half steel;

R bessemerizes the basicity that the requirement of terminal point slag reaches, and R gets 3.5～4.5;

η ₁Be the mass percent of CaO in the quickened lime that adds, unit is %;

η ₂Be SiO in the slag former that adds ₂Mass percent, unit is %;

η ₃Be the mass percent of CaO in the slag former that adds, unit is %;

η ₄Be the mass percent of CaO in the high magnesium lime that adds, unit is %.

6. like claim 3 or 4 described slagging methods, the adding total amount that it is characterized in that said quickened lime is 25～50Kg/ ton steel, and said quickened lime contains the CaO above 85% by weight percentage; The adding total amount of said high magnesium lime is 15～25Kg/ ton steel, and said high magnesium lime contains 45%～55% CaO and 30%～50% MgO by weight percentage.

7. slagging method as claimed in claim 3; The add-on that it is characterized in that the quickened lime of said first adding accounts for 70%～80% of the total add-on of quickened lime; The said add-on that first adds high magnesium lime accounts for 65%～75% of the total add-on of high magnesium lime; And basicity of slag is controlled between 2～2.5; And the blowing oxygen quantity of smelting when half steel reach be blown in the whole half steel smelting process amount of oxygen 65%～75% the time, add second mass products property lime and the high magnesium lime.

8. slagging method as claimed in claim 4; It is characterized in that in said slagging method; The add-on of the said slag former of first adding accounts for 60～70% of the total add-on of said slag former; The add-on of the quickened lime of first adding accounts for 65%～75% of the total add-on of quickened lime; The add-on of the high magnesium lime of first adding accounts for 50%～60% of the total add-on of high magnesium lime; And the blowing oxygen quantity of smelting when half steel reach be blown in the whole half steel smelting process amount of oxygen 60%～70% the time, add second batch of slag making raw material.

9. like claim 3 or 4 described slagging methods; It is characterized in that said slagging method also was included in into stove half steel temperature greater than 1350 ℃ and carbon content greater than 3.60% o'clock; After adding first slag making raw material, in converter, add the steel-making of 4～8Kg/ ton steel in the time of blowing 2min and use sludge ball, said steel-making contains 25wt%～40wt% ferriferous oxide by weight percentage with sludge ball.

10. like claim 3 or 4 described slagging methods; Before it is characterized in that said slagging method also is included in converter tapping; In converter, add the residue adjustment operation of slag supplying agent, thereby reduce the following quantity of slag when tapping and guarantee the requirement of slag splashing operation slag viscosity with working the slag viscosity.