阅读说明：本技术 一种转炉冶炼半钢加速化渣的方法 (Method for accelerating slagging of converter smelting semisteel ) 是由 郑力飞 吴雨晨 方鸣 李亚厚 韩磊 曹斌 于 2020-12-28 设计创作，主要内容包括：本发明提供了一种转炉冶炼半钢加速化渣的方法,所述方法包括以下步骤：(1)炉膛温度<1000℃的转炉内加入原渣,然后加入半钢；(2)进行供氧顶吹,所述供氧顶吹包括依次进行的第一顶吹、第二顶吹、第三顶吹、第四顶吹以及第五顶吹,然后转炉出钢；所述第二顶吹时添加第一渣料；所述第三顶吹时添加第二渣料；所述第四顶吹时添加第三渣料。本发明利用原渣本身的多组元易熔化的特性使炼钢转炉在吹炼初期尽早形成初渣,起到加快化渣的效果,实现吹炼前期的有效脱磷；而且,本发明提供的方法适用于检修后炉膛温度<1000℃的转炉,保证了转炉炼钢的效率。(The invention provides a method for accelerating slagging of semisteel smelted by a converter, which comprises the following steps: (1) adding raw slag into a converter with the hearth temperature of less than 1000 ℃, and then adding semisteel; (2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter; adding a first slag charge during the second top blowing; adding a second slag charge during the third top blowing; and adding a third slag during the fourth top blowing. The invention utilizes the characteristic that the multi-component of the raw slag is easy to melt, so that the steelmaking converter forms the initial slag as early as possible in the initial stage of blowing, the effect of accelerating slag melting is achieved, and the effective dephosphorization in the early stage of blowing is realized; moreover, the method provided by the invention is suitable for the converter with the hearth temperature of less than 1000 ℃ after maintenance, and the steelmaking efficiency of the converter is ensured.)

1. The method for accelerating slagging of semisteel smelted by using the converter is characterized by comprising the following steps:

(1) adding raw slag into a converter with the hearth temperature less than 1000 ℃, and then adding semisteel;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

adding a first slag charge during the second top blowing;

adding a second slag charge during the third top blowing;

and adding a third slag during the fourth top blowing.

2. The method according to claim 1, wherein the raw slag of step (1) comprises, in mass percent: 28-35% of CaO and 7-10% of SiO₂9-12% of MgO, 0.08-0.11% of P, 18-25% of FeO and inevitable impurities;

preferably, the addition amount of the raw slag in the step (1) is 20-40kg/t_Semisteel。

3. The method as claimed in claim 1 or 2, wherein the temperature of the semi-steel in step (1) is 1380-1420 ℃;

preferably, the semisteel in the step (1) comprises the following components in percentage by mass: 3.6-4% of C, 0.03-0.04% of S and 0.09-0.12% of P, the balance being Fe and unavoidable impurities, the content of unavoidable impurities being trace.

4. The method according to any one of claims 1 to 3, wherein the conditions of the first top-blowing of step (2) are: the lance position of the oxygen lance is 1.1-1.3m, the oxygen flow is 26000 and 28000Nm³H, 3 to 4Nm of oxygen³/t。

5. The method according to any one of claims 1 to 4, wherein the conditions of the second top-blowing of step (2) are: the lance position of the oxygen lance is 1.3-1.4m, the oxygen flow is 23000-25000Nm³H, 5-6Nm of oxygen³/t；

Preferably, the first slag includes first lime and/or bauxite;

preferably, the adding amount of the first lime is 7-8kg/t_Semisteel；

Preferably, the addition amount of the bauxite is 4-6kg/t_Semisteel；

Preferably, the bauxite has an average particle size of 5-30mm, and the proportion of particles with particle sizes less than 5mm to particles with particle sizes greater than 30mm is less than 5%;

preferably, the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃Is 8-15%.

6. The process according to any one of claims 1 to 5, wherein the conditions of the third top-blowing of step (2) are: the lance position of the oxygen lance is 1.4-1.6m, the oxygen flow is 22000-23000Nm³H, oxygen supply 14-15Nm³/t；

Preferably, the second slag comprises second lime and/or first soft burnt dolomite;

preferably, the addition amount of the second lime is 10-11kg/t_Semisteel；

Preferably, the addition amount of the first light-burned dolomite is 6-7kg/t_Semisteel；

Preferably, the average granularity of the first light-burned dolomite is 5-50mm, and the proportion of the granularity smaller than 5mm is less than or equal to 15 percent;

preferably, the first light burned dolomite comprises, in mass percent: CaO is more than or equal to 38 percent, and MgO is more than or equal to 27 percent.

7. The process according to any one of claims 1 to 6, wherein the conditions of the fourth top-blowing of step (2) are: the lance position of the oxygen lance is 1.2-1.4m, the oxygen flow is 25000-26000Nm³H, 6 to 7Nm of oxygen supply³/t；

Preferably, the third slag comprises a second lightly calcined dolomite;

preferably, the addition amount of the second light-burned dolomite is 6-7kg/t_Semisteel；

Preferably, the average grain size of the second light-burned dolomite is 5-50mm, and the proportion of the grain size smaller than 5mm is less than or equal to 15 percent;

preferably, the second light burned dolomite comprises, in mass percent: CaO is more than or equal to 38 percent, and MgO is more than or equal to 27 percent.

8. The method according to any one of claims 1 to 7, wherein the conditions of the fifth top-blowing of step (2) are as follows: the lance position of the oxygen lance is 1.1-1.2m, the oxygen flow is 26000 and 28000Nm³H, supplying oxygen to the end of blowing.

9. The method according to any one of claims 1 to 8, wherein the semisteel of step (1) is mixed with a third lime before being added to the hearth of the converter;

preferably, the addition amount of the third lime is 2-4kg/t_Semisteel；

Preferably, the average particle size of the third lime is 5-10 mm;

preferably, the third lime comprises, by mass percent: CaO (CaO)>85％，SiO₂<3% moisture<0.5 percent, less than or equal to 0.025 percent of P and less than or equal to 0.08 percent of S;

preferably, the activity of the third lime is > 250.

10. A method according to any one of claims 1 to 9, characterized in that the method comprises the steps of:

(1) the furnace hearth temperature is less than 1000 ℃, and the addition is carried out according to the proportion of 20-40kg/t_SemisteelAdding the raw slag, and then adding the semisteel with the temperature of 1380-1420 ℃; before the semisteel is added into a hearth of a converter, mixing the semisteel with third lime with the average particle size of 5-10 mm; the addition amount of the third lime is 2-4kg/t_Semisteel(ii) a The third lime comprises the following components in percentage by mass: CaO (CaO)>85％，SiO₂<3% moisture<0.5 percent, less than or equal to 0.025 percent of P and less than or equal to 0.08 percent of S;

the raw slag comprises the following components in percentage by mass: 28-35% of CaO and 7-10% of SiO₂9-12% of MgO, 0.08-0.11% of P, 18-25% of FeO and inevitable impurities;

the semisteel comprises the following components in percentage by mass: 3.6-4% of C, 0.03-0.04% of S and 0.09-0.12% of P, the balance being Fe and unavoidable impurities, the content of the unavoidable impurities being trace;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

the conditions of the first top blowing are as follows: the lance position of the oxygen lance is 1.1-1.3m, the oxygen flow is 26000 and 28000Nm³H, 3 to 4Nm of oxygen³/t；

The conditions of the second top blowing are as follows: the lance position of the oxygen lance is 1.3-1.4m, the oxygen flow is 23000-25000Nm³H, 5-6Nm of oxygen³/t；

Adding a first slag material during the second top blowing, wherein the first slag material comprises first lime and/or bauxite; the addition amount of the first lime is 7-8kg/t_Semisteel(ii) a The addition amount of the bauxite is 4-6kg/t_Semisteel(ii) a The average particle size of the bauxite is 5-30mm, and the proportion of the average particle size of less than 5mm to the average particle size of more than 30mm is less than 5%; the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃8 to 15 percent;

the third top blowing conditions are as follows: the lance position of the oxygen lance is 1.4-1.6m, the oxygen flow is 22000-23000Nm³H, oxygen supply 14-15Nm³/t；

Adding a second slag charge during the third top blowing; the second slag comprises second lime and/or first light burned dolomite; the addition amount of the second lime is 10-11kg/t_Semisteel(ii) a The addition amount of the first light-burned dolomite is 6-7kg/t_Semisteel(ii) a The average granularity of the first light-burned dolomite is 5-50mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the first light burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fourth top blowing conditions are as follows: the lance position of the oxygen lance is 1.2-1.4m, the oxygen flow is 25000-26000Nm³H, 6 to 7Nm of oxygen supply³/t；

Adding third slag during the fourth top blowingFeeding; the third slag comprises second light burned dolomite; the addition amount of the second light-burned dolomite is 6-7kg/t_Semisteel(ii) a The average granularity of the second light-burned dolomite is 5-50mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the second light-burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fifth top blowing condition is as follows: the lance position of the oxygen lance is 1.1-1.2m, the oxygen flow is 26000 and 28000Nm³H, supplying oxygen to the end of blowing.

Technical Field

The invention belongs to the technical field of steelmaking, relates to a converter steelmaking method, and particularly relates to a converter smelting semisteel slagging acceleration method.

Background

The steelmaking slag is a general name of products formed by oxidizing impurities in metal materials in a steelmaking process by an oxidant to generate oxides and then carrying out physical and chemical reactions with a slagging agent and a furnace lining. The slag density is lower than that of molten steel, the slag usually covers the surface of the molten steel, and during smelting, because of the generation of a large amount of gas, intense stirring is generated in a molten pool, the slag and the molten steel are always in a mutual mixing state, and the mixing degree is more developed, and the refining effect of molten steel by the molten slag is quicker.

Because the continuous reaction between the slag and the molten steel, the components and properties of the slag are continuously changed in the smelting process, the properties of the slag are directly related to the final quality of the molten steel, and the main task of steel making is to remove harmful impurities in the molten steel to the maximum extent, which mainly depends on the refining effect of the slag, so that the components and the temperature of the slag need to be continuously adjusted in the smelting process.

China has abundant vanadium titano-magnetite resources, the main raw materials for converter steelmaking are semisteel after vanadium extraction through a special converter, the mass percent of carbon in the semisteel obtained after vanadium-containing molten iron is desulfurized and vanadium extracted is 3.4-4%, the mass percent of sulfur is 0.03-0.04%, the mass percent of P is 0.09-0.12%, and the mass percent of other elements is trace, so that the semisteel smelting has the characteristics of less acidic slag forming substances, single slag system component, insufficient heat and the like in the blowing process. Particularly, the temperature of a hearth of the converter is less than 1000 ℃ caused by maintenance sometimes, and is far lower than the temperature during normal smelting, the components of the semisteel after vanadium extraction except carbon and iron have low content of other elements, and the problems of long time for forming initial slag, low dephosphorization rate and high auxiliary material consumption rate exist in semisteel smelting under the condition.

CN 103320566A discloses a method for smelting semisteel by a double-slag method, which comprises the following steps: adding the semisteel into a steelmaking converter and adding a first batch of slagging material to carry out primary slagging blowing, wherein the oxygen supply intensity of a top-blown oxygen lance is controlled to be 1.5-2.5m within 90s after the blowing begins³V (min. t), the position of the oxygen lance is 1.5-2.5 m; controlling the oxygen supply intensity of the top-blown oxygen lance to be 2.5-3.5m after the blowing starts for 90s³V (min. t), the position of the oxygen lance is 1.8-2.5 m; when the carbon content of the molten steel in the converter reaches 0.4-0.8 percent, the steel is solidifiedBlowing for the first time and deslagging; adding a second batch of slagging material into the converter for secondary slagging blowing, and controlling the oxygen supply intensity of the top-blown oxygen lance to be 3.5-4m in the blowing process³V (min. t), the oxygen lance position is 1.4-2 m; and tapping after the blowing is finished.

CN 102559984A discloses a method for producing high-carbon steel through double-slag-method high-carbon-drawing tapping, which comprises the following steps: charging molten iron and scrap steel into the converter according to a certain molten iron phase ratio; the first stage of converter smelting is 2.8m³Blowing with oxygen supply intensity of v (min. t), adding active lime and an ore slagging agent into the converter, and stirring with a large low blowing flow; blowing at the standard gun position in the early stage of converter blowing, and then gradually increasing the gun position; pouring out part of slag by rocking the furnace; the second stage of converter blowing was at 3.3m³Blowing with oxygen supply intensity of min.t, and adding active lime and an ore slagging agent into the converter; in the later period, a gun position system of blowing at a higher gun position and descending the guns section by section is adopted; adding a small amount of ore and fluorite in batches within 80-90% of the total blowing oxygen consumption; after the converter blowing is finished, the converter is shaken to pour slag, measure the temperature and sample; and (5) tapping from the converter.

CN 103266199A discloses a semisteel steelmaking slagging process and a semisteel steelmaking method, wherein the slagging process comprises the following steps: adding the semisteel subjected to vanadium extraction into a steelmaking furnace; after the lower oxygen lance successfully blows oxygen and ignites, 1-5kg/t of slag steel and 4.5-7kg/t of quartz sand are added; after 2.8-3.2 minutes from the beginning of blowing, 8-10kg/t of lime, 7-9kg/t of high-magnesium lime and 5-11kg/t of composite slagging agent are added; and (3) adding 7-9kg/t of lime and 7-12kg/t of high-magnesium lime into the steelmaking furnace within 7-8min from the formation of the primary slag to the start of blowing, and continuing blowing until the components of the molten steel are qualified to obtain the target molten steel and the final slag.

However, the above method has problems of late slag formation time in the initial stage of semisteel smelting, poor dephosphorization effect and high auxiliary material consumption. Therefore, it is needed to provide a method for accelerating slagging of semisteel smelted by a converter so as to increase slagging speed of the semisteel, thereby ensuring desulfurization, dephosphorization and decarburization efficiency of the semisteel.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a method for accelerating slagging of semisteel smelted by a converter, in particular to a method for accelerating slagging of semisteel smelted by a converter with the hearth temperature less than 1000 ℃, and the method can ensure that semisteel rapidly forms slag in the converter steelmaking process, thereby ensuring the efficiency of desulfurization, dephosphorization and decarburization of the semisteel.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for accelerating slagging of semisteel smelted by a converter, which comprises the following steps:

(1) adding raw slag into a converter with the hearth temperature less than 1000 ℃, and then adding semisteel;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

adding a first slag charge during the second top blowing;

adding a second slag charge during the third top blowing;

and adding a third slag during the fourth top blowing.

The method is not only suitable for traditional converter steelmaking, but also can ensure that the overhauled converter can smoothly and rapidly form slag, and improve the converter steelmaking efficiency. The raw slag is poured before slag splashing and furnace protection, and has good melting property, more pores, uniform components and good melting condition. The invention makes use of the characteristic that the multicomponent of the raw slag is easy to melt to form the initial slag as early as possible in the initial stage of the blowing by adding the raw slag, thereby achieving the effect of accelerating the slagging and effectively dephosphorizing in the early stage of the blowing.

Preferably, the raw slag of step (1) comprises: 28-35% of CaO and 7-10% of SiO₂9-12% of MgO, 0.08-0.11% of P, 18-25% of FeO and inevitable impurities.

The raw slag of the invention contains 28 to 35 mass percent of CaO, for example, 28, 29, 30, 31, 32, 33, 34 or 35 mass percent of CaO, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

SiO in the raw slag of the invention₂The content of (b) is 7 to 10% by mass, and may be, for example, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.

The raw slag of the present invention contains 9 to 12% by mass of MgO, for example, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, or 12%, but is not limited to the values listed above, and other values not listed in the numerical range are also applicable.

The raw slag of the present invention contains 0.08 to 0.11% by mass of P, for example, 0.08%, 0.09%, 0.1% or 0.11%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.

The mass percentage of FeO in the raw slag of the invention is 18-25%, for example 18%, 19%, 20%, 21%, 22%, 23%, 24% or 25%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the addition amount of the raw slag in the step (1) is 20-40kg/t_SemisteelFor example, it may be 20kg/t_Semisteel、25kg/t_Semisteel、30kg/t_Semisteel、35kg/t_SemisteelOr 40kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the temperature of the semisteel in step (1) is 1380-1420 ℃, such as 1380 ℃, 1390 ℃, 1400 ℃, 1410 ℃ or 1420 ℃, but not limited to the recited values, and other unrecited values in the range of values are equally applicable.

Preferably, the semisteel in the step (1) comprises the following components in percentage by mass: 3.6-4% of C, 0.03-0.04% of S and 0.09-0.12% of P, the balance being Fe and unavoidable impurities, the content of unavoidable impurities being trace.

The C content in the semi-steel in the step (1) is 3.6-4% by mass, for example, 3.6%, 3.7%, 3.8%, 3.9% or 4%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

The S content in the semi-steel in the step (1) is 0.03-0.04% by mass, for example, 0.03%, 0.032%, 0.035%, 0.036% or 0.04%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

The P content in the semi-steel in the step (1) is 0.09-0.12% by mass, for example, 0.09%, 0.10%, 0.11% or 0.12%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the conditions of the first top-blowing in the step (2) are as follows: the lance position is 1.1-1.3m, such as 1.1m, 1.15m, 1.2m, 1.25m or 1.3m, but not limited to the values listed, and other values not listed in the numerical range are also applicable; the oxygen flow rate is 26000 and 28000Nm³For example, 26000, 26500, 27000, 27500 or 28000, but not limited to the values listed, other values not listed in the numerical range are equally suitable; oxygen supply 3-4Nm³T, may be, for example, 3Nm³/t、3.2Nm³/t、3.5Nm³/t、3.8Nm³T or 4Nm³T, but is not limited to the values recited, other values within the range of values not recited are equally applicable.

Preferably, the conditions of the second top-blowing in the step (2) are as follows: the lance position is 1.3-1.4m, such as 1.3m, 1.32m, 1.35m, 1.36m, 1.38m or 1.4m, but not limited to the values listed, and other values not listed in the range of values are also applicable; oxygen flow rate of 23000 and 25000Nm³H, for example 23000Nm³/h、23500Nm³/h、24000Nm³/h、24500Nm³H or 25000Nm³The values are not limited to the values listed, other values not listed in the numerical ranges are equally applicable; oxygen supply 5-6Nm³T, may be, for example, 5Nm³/t、5.2Nm³/t、5.4Nm³/t、5.6Nm³/t、5.8Nm³T or 6Nm³T, but is not limited to the values recited, other values within the range of values not recited are equally applicable.

Preferably, the first slag includes first lime and/or bauxite.

The first lime is CaO.

Preferably, the adding amount of the first lime is 7-8kg/t_SemisteelFor example, it may be 7kg/t_Semisteel、7.2kg/t_Semisteel、7.5kg/t_Semisteel、7.8kg/t_SemisteelOr 8kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the addition amount of the bauxite is 4-6kg/t_SemisteelFor example, it may be 4kg/t_Semisteel、4.5kg/t_Semisteel、5kg/t_Semisteel、5.5kg/t_SemisteelOr 6kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the bauxite has an average particle size of 5 to 30mm and the proportion of particles having a particle size of less than 5mm to particles having a particle size of greater than 30mm is less than 5%.

The bauxite may have an average particle size of 5 to 30mm, for example 5mm, 10mm, 15mm, 20mm, 25mm or 30mm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.

Preferably, the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃Is 8-15%.

Al in the bauxite of the invention₂O₃The content of (b) is not less than 38% by mass, and may be, for example, 38%, 39%, 40%, 41%, 42%, 45%, 50% or 55%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.

SiO in the bauxite₂The percentage by mass of (b) is < 30%, and may be, for example, 10%, 15%, 21%, 24%, 25%, 27%, 28% or 29%, but is not limited to the values recited, and other values not recited within the numerical range are also applicable.

Fe in the bauxite of the invention₂O₃The content of (b) is 8-15% by mass, for example, 8%,9%, 10%, 11%, 12%, 13%, 14% or 15%, but not limited to the recited values, other values not recited in the numerical range are equally applicable.

Preferably, the conditions of the third top-blowing in the step (2) are as follows: the lance position is 1.4-1.6m, such as 1.4m, 1.45m, 1.5m, 1.55m or 1.6m, but not limited to the values listed, and other values not listed in the numerical range are also applicable; the oxygen flow rate is 22000-³H, for example 22000Nm³/h、22200Nm³/h、22500Nm³/h、22700Nm³/h、22800Nm³H or 23000Nm³The values are not limited to the values listed, other values not listed in the numerical ranges are equally applicable; oxygen supply 14-15Nm³T, for example, may be 14Nm³/t、14.2Nm³/t、14.5Nm³/t、14.8Nm³T or 15Nm³T, but is not limited to the values recited, other values within the range of values not recited are equally applicable.

Preferably, the second slag comprises second lime and/or first soft burnt dolomite.

The second lime is CaO.

Preferably, the addition amount of the second lime is 10-11kg/t_SemisteelFor example, it may be 10kg/t_Semisteel、10.2kg/t_Semisteel、10.5kg/t_Semisteel、10.8kg/t_SemisteelOr 11kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the addition amount of the first light-burned dolomite is 6-7kg/t_SemisteelFor example, it may be 6kg/t_Semisteel、6.2kg/t_Semisteel、6.4kg/t_Semisteel、6.5kg/t_Semisteel、6.6kg/t_Semisteel、6.8kg/t_SemisteelOr 7kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the granularity of the first light-burned dolomite is 5-50mm, and the proportion of the granularity smaller than 5mm is less than or equal to 15%.

The first lightly calcined dolomite has an average particle size of from 5 to 50mm, and may be, for example, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm or 50mm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.

Preferably, the first light burned dolomite comprises, in mass percent: CaO is more than or equal to 38 percent, and MgO is more than or equal to 27 percent.

The content of CaO in the first lightly calcined dolomite according to the present invention is not less than 38% by mass, and may be, for example, 38%, 39%, 40%, 41%, 42%, 45%, 50% or 55%, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

The first soft burned dolomite according to the present invention may have a MgO content of 27% by mass or more, for example, 27%, 30%, 35%, 36%, 40%, 45%, 48%, or 55%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.

Preferably, the fourth top-blowing condition in the step (2) is as follows: the lance position is 1.2-1.4m, such as 1.2m, 1.25m, 1.3m, 1.35m or 1.4m, but not limited to the values listed, and other values not listed in the numerical range are also applicable; oxygen flow 25000-26000Nm³H, for example 25000Nm³/h、25200Nm³/h、25500Nm³/h、25800Nm³H or 26000Nm³The values are not limited to the values listed, other values not listed in the numerical ranges are equally applicable; oxygen supply 6-7Nm³T, may be, for example, 6Nm³/t、6.2Nm³/t、6.5Nm³/t、6.8Nm³T or 7Nm³T, but is not limited to the values recited, other values within the range of values not recited are equally applicable.

Preferably, the third slag comprises a second lightly calcined dolomite.

Preferably, the addition amount of the second light-burned dolomite is 6-7kg/t_SemisteelFor example, it may be 6kg/t_Semisteel、6.2kg/t_Semisteel、6.4kg/t_Semisteel、6.5kg/t_Semisteel、6.6kg/t_Semisteel、6.8kg/t_SemisteelOr 7kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the granularity of the second light-burned dolomite is 5-50mm, and the proportion of the granularity smaller than 5mm is less than or equal to 15%.

The second lightly calcined dolomite has an average particle size of from 5 to 50mm, and may be, for example, 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm or 50mm, but is not limited to the values recited, and other values not recited in the numerical range are equally applicable.

Preferably, the second light burned dolomite comprises, in mass percent: CaO is more than or equal to 38 percent, and MgO is more than or equal to 27 percent.

The content of CaO in the first lightly calcined dolomite according to the present invention is not less than 38% by mass, and may be, for example, 38%, 39%, 40%, 41%, 42%, 45%, 50% or 55%, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

The first soft burned dolomite according to the present invention may have a MgO content of 27% by mass or more, for example, 27%, 30%, 35%, 36%, 40%, 45%, 48%, or 55%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.

Preferably, the conditions of the fifth top-blowing in the step (2) are as follows: the lance position is 1.1-1.2m, such as 1.1m, 1.12m, 1.15m, 1.18m or 1.2m, but not limited to the values listed, and other values not listed in the numerical range are also applicable; the oxygen flow rate is 26000 and 28000Nm³H, for example, 26000Nm³/h、26500Nm³/h、27000Nm³/h、27500Nm³H or 28000Nm³The values are not limited to the values listed, other values not listed in the numerical ranges are equally applicable; oxygen was supplied to the end of the blowing.

The term "supplying oxygen to the end of converting" in the fifth top-blowing of the present invention means that oxygen is supplied in an amount of not more than 18Nm in the fifth top-blowing of the present invention until the time of the combined tapping of the steel³The above requirements can be achieved by t.

Oxygen supply amount "Nm" according to the invention³And/t' is the amount of oxygen supplied per ton of semisteel.

Preferably, the semisteel obtained in the step (1) is mixed with third lime before being added into a hearth of the converter.

Preferably, the addition amount of the third lime is 2-4kg/t_SemisteelFor example, it may be 2kg/t_Semisteel、2.5kg/t_Semisteel、3kg/t_Semisteel、3.5kg/t_SemisteelOr 4kg/t_SemisteelBut are not limited to the recited values, and other values within the numerical range not recited are equally applicable.

Preferably, the third lime has an average particle size of 5 to 10mm, for example 5mm, 6mm, 7mm, 8mm, 9mm or 10mm, but is not limited to the values recited, and other values not recited within the range of values are equally applicable.

Preferably, the third lime comprises, by mass percent: CaO (CaO)>85％，SiO₂<3% moisture<0.5 percent, less than or equal to 0.025 percent of P and less than or equal to 0.08 percent of S.

The content of CaO in the third lime according to the present invention is > 85% by mass, for example, 86%, 88%, 90%, 92% or 95%, but not limited to the recited values, and other values not recited in the range of values are also applicable.

SiO in the third lime₂In percentage by mass of<3%, for example 0.5%, 1%, 1.5%, 2%, 2.5% or 2.8%, but not limited to the recited values, other values not recited in the numerical range are equally applicable.

The moisture content of the third lime of the present invention is less than 0.5% by mass, and may be, for example, 0.1%, 0.2%, 0.3%, 0.4%, or 0.49%, but is not limited to the values listed, and other values not listed in the numerical range are also applicable.

The content of P in the third lime according to the invention is less than or equal to 0.025% by mass, and may be, for example, 0.005%, 0.01%, 0.015%, 0.02% or 0.025%, but is not limited to the values listed, and other values not listed in the numerical range are equally applicable.

The content of S in the third lime according to the present invention is equal to or less than 0.08% by mass, and may be, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, or 0.08%, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the activity of the third lime is >250, which may be, for example, 255, 260, 265, 270 or 280, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

As a preferred technical scheme of the method, the method comprises the following steps:

(1) the furnace hearth temperature is less than 1000 ℃, and the addition is carried out according to the proportion of 20-40kg/t_SemisteelAdding the raw slag, and then adding the semisteel with the temperature of 1380-1420 ℃; before the semisteel is added into a hearth of a converter, mixing the semisteel with third lime with the average particle size of 5-10 mm; the addition amount of the third lime is 2-4kg/t_Semisteel(ii) a The third lime comprises the following components in percentage by mass: CaO (CaO)>85％，SiO₂<3% moisture<0.5 percent, less than or equal to 0.025 percent of P and less than or equal to 0.08 percent of S;

the raw slag comprises the following components in percentage by mass: 28-35% of CaO and 7-10% of SiO₂9-12% of MgO, 0.08-0.11% of P, 18-25% of FeO and inevitable impurities;

the semisteel comprises the following components in percentage by mass: 3.6-4% of C, 0.03-0.04% of S and 0.09-0.12% of P, the balance being Fe and unavoidable impurities, the content of the unavoidable impurities being trace;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

the conditions of the first top blowing are as follows: the lance position of the oxygen lance is 1.1-1.3m, the oxygen flow is 26000 and 28000Nm³H, 3 to 4Nm of oxygen³/t；

The conditions of the second top blowing are as follows: the lance position of the oxygen lance is 1.3-1.4m, the oxygen flow is 23000-25000Nm³H, 5-6Nm of oxygen³/t；

Adding a first slag material during the second top blowingThe first slag comprises first lime and/or bauxite; the addition amount of the first lime is 7-8kg/t_Semisteel(ii) a The addition amount of the bauxite is 4-6kg/t_Semisteel(ii) a The average particle size of the bauxite is 5-30mm, and the proportion of the average particle size of less than 5mm to the average particle size of more than 30mm is less than 5%; the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃8 to 15 percent;

the third top blowing conditions are as follows: the lance position of the oxygen lance is 1.4-1.6m, the oxygen flow is 22000-23000Nm³H, oxygen supply 14-15Nm³/t；

Adding a second slag charge during the third top blowing; the second slag comprises second lime and/or first light burned dolomite; the addition amount of the second lime is 10-11kg/t_Semisteel(ii) a The addition amount of the first light-burned dolomite is 6-7kg/t_Semisteel(ii) a The average granularity of the first light-burned dolomite is 5-50mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the first light burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fourth top blowing conditions are as follows: the lance position of the oxygen lance is 1.2-1.4m, the oxygen flow is 25000-26000Nm³H, 6 to 7Nm of oxygen supply³/t；

Adding a third slag material during the fourth top blowing; the third slag comprises second light burned dolomite; the addition amount of the second light-burned dolomite is 6-7kg/t_Semisteel(ii) a The average granularity of the second light-burned dolomite is 5-50mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the second light-burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fifth top blowing condition is as follows: the lance position of the oxygen lance is 1.1-1.2m, the oxygen flow is 26000 and 28000Nm³H, supplying oxygen to the end of blowing.

The recitation of numerical ranges herein includes not only the above-recited numerical values, but also any numerical values between non-recited numerical ranges, and is not intended to be exhaustive or to limit the invention to the precise numerical values encompassed within the range for brevity and clarity.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention utilizes the characteristic that the multi-component of the raw slag is easy to melt, so that the steelmaking converter forms the initial slag as early as possible in the initial stage of blowing, the effect of accelerating slag melting is achieved, and the effective dephosphorization in the early stage of blowing is realized; moreover, the method provided by the invention is suitable for the converter with the hearth temperature of less than 1000 ℃ after maintenance, and the steelmaking efficiency of the converter is ensured;

(2) the method provided by the invention is suitable for smelting semisteel by using the converter with the hearth temperature less than 1000 ℃, and has the advantages of high slagging speed and high dephosphorization efficiency.

Detailed Description

The technical solutions of the present invention are further described below by means of specific embodiments, which are provided only for facilitating understanding of those skilled in the art, and should not be construed as limiting the technical solutions of the present invention.

Example 1

Taking converter smelting of HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of semisteel smelted by a converter, and the method comprises the following steps:

(1) the furnace hearth temperature is 800 ℃, and the charging is carried out according to the proportion of 30kg/t_SemisteelAdding the raw slag, and then adding semisteel with the temperature of 1400 ℃;

the raw slag comprises the following components in percentage by mass: 32% of CaO, 8% of SiO₂10% of MgO, 0.09% of P, 21% of FeO and inevitable impurities;

the semisteel comprises the following components in percentage by mass: 3.8% of C, 0.035% of S and 0.1% of P, the balance being Fe and unavoidable impurities, the content of said unavoidable impurities being trace;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

the conditions of the first top blowing are as follows: the lance position of the oxygen lance is 1.2m, and the oxygen flow is 27000Nm³H, 3.5Nm of oxygen³/t；

The conditions of the second top blowing are as follows: the lance position of the oxygen lance is 1.35m, and the oxygen flow is 24000Nm³H, 5.5Nm of oxygen supply³/t；

Adding a first slag material during the second top blowing, wherein the first slag material comprises first lime and bauxite; the addition amount of the first lime is 7.5kg/t_Semisteel(ii) a The addition amount of the bauxite is 5kg/t_Semisteel(ii) a The average particle size of the bauxite is 15mm, and the proportion of the average particle size of less than 5mm to the average particle size of more than 30mm is less than 5%; the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃Is 12%;

the third top blowing conditions are as follows: the lance position of the oxygen lance is 1.5m, and the oxygen flow is 22500Nm³H, oxygen supply 14.5Nm³/t；

Adding a second slag charge during the third top blowing; the second slag comprises second lime and first light-burned dolomite; the addition amount of the second lime is 10.5kg/t_Semisteel(ii) a The addition amount of the first light-burned dolomite is 6.5kg/t_Semisteel(ii) a The average granularity of the first light-burned dolomite is 30mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the first light burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fourth top blowing conditions are as follows: the lance position of the oxygen lance is 1.3m, and the oxygen flow is 25500Nm³H, 6.5Nm of oxygen supply³/t；

Adding a third slag material during the fourth top blowing; the third slag comprises second light burned dolomite; the addition amount of the second light-burned dolomite is 6.5kg/t_Semisteel(ii) a The average granularity of the second light-burned dolomite is 30mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the second light-burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fifth top blowing condition is as follows: the lance position of the oxygen lance is 1.15m, and the oxygen flow is 27000Nm³H, oxygen supply 13Nm³/t。

In this embodiment, the first lime and the second lime are CaO.

Example 2

Taking converter smelting of HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of semisteel smelted by a converter, and the method comprises the following steps:

(1) the furnace hearth temperature is 800 ℃, and the addition is carried out according to the proportion of 20kg/t_SemisteelAdding the raw slag, and then adding the semisteel with the temperature of 1420 ℃;

the raw slag comprises the following components in percentage by mass: 28% of CaO, 7% of SiO₂9% of MgO, 0.08% of P, 18% of FeO and inevitable impurities;

the semisteel comprises the following components in percentage by mass: 3.6% of C, 0.03% of S and 0.09% of P, the balance being Fe and unavoidable impurities, the unavoidable impurities being present in trace amounts;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

the conditions of the first top blowing are as follows: the lance position of the oxygen lance is 1.1m, and the oxygen flow is 26000Nm³H, 3Nm oxygen supply³/t；

The conditions of the second top blowing are as follows: the lance position of the oxygen lance is 1.3m, and the oxygen flow is 23000Nm³H, 5Nm of oxygen supply³/t；

Adding a first slag material during the second top blowing, wherein the first slag material comprises first lime and bauxite; the addition amount of the first lime is 7kg/t_Semisteel(ii) a The addition amount of the bauxite is 4kg/t_Semisteel(ii) a The average particle size of the bauxite is 8mm, and the proportion of the average particle size of less than 5mm to the average particle size of more than 30mm is less than 5%; the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃8 percent;

the third top blowing conditions are as follows: the lance position of the oxygen lance is 1.4m, and the oxygen flow is 22000Nm³H, oxygen supply 14Nm³/t；

Adding a second slag charge during the third top blowing; the second slag comprises second lime and first light-burned dolomite; the addition amount of the second lime is 10kg/t_Semisteel(ii) a The addition amount of the first light-burned dolomite is 6kg/t_Semisteel(ii) a The average granularity of the first light-burned dolomite is 10mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the first light burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fourth top blowing conditions are as follows: the lance position of the oxygen lance is 1.2m, the oxygen flow is 25000Nm³H, 6Nm of oxygen supply³/t；

Adding a third slag material during the fourth top blowing; the third slag comprises second light burned dolomite; the addition amount of the second light-burned dolomite is 6kg/t_Semisteel(ii) a The average granularity of the second light-burned dolomite is 10mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the second light-burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fifth top blowing condition is as follows: the lance position of the oxygen lance is 1.1m, and the oxygen flow is 26000Nm³H, oxygen supply 14Nm³/t。

In this embodiment, the first lime and the second lime are CaO.

Example 3

Taking converter smelting of HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of semisteel smelted by a converter, and the method comprises the following steps:

(1) the furnace hearth temperature is 800 ℃, and the charging is carried out according to the proportion of 40kg/t_SemisteelAdding the raw slag, and then adding semisteel with the temperature of 1380 ℃;

the raw slag comprises the following components in percentage by mass: 35% of CaO, 10% of SiO₂12% of MgO, 0.11% of P, 25% of FeO and inevitable impurities;

the semisteel comprises the following components in percentage by mass: 4% of C, 0.04% of S and 0.12% of P, the balance being Fe and unavoidable impurities, the content of said unavoidable impurities being trace amounts;

(2) carrying out oxygen supply top blowing, wherein the oxygen supply top blowing comprises first top blowing, second top blowing, third top blowing, fourth top blowing and fifth top blowing which are carried out in sequence, and then tapping from a converter;

the conditions of the first top blowing are as follows: the lance position of the oxygen lance is 1.3m, and the oxygen flow is 28000Nm³H, 4Nm of oxygen supply³/t；

The conditions of the second top blowing are as follows: the lance position of the oxygen lance is 1.4m, the oxygen flow is 25000Nm³H, 6Nm of oxygen supply³/t；

Adding a first slag material during the second top blowing, wherein the first slag material comprises first lime and bauxite; the addition amount of the first lime is 8kg/t_Semisteel(ii) a The addition amount of the bauxite is 6kg/t_Semisteel(ii) a The average particle size of the bauxite is 25mm, and the proportion of the average particle size of less than 5mm to the average particle size of more than 30mm is less than 5%; the bauxite comprises the following components in percentage by mass: al (Al)₂O₃≥38％，SiO₂＜30％，Fe₂O₃15 percent;

the third top blowing conditions are as follows: the lance position of the oxygen lance is 1.6m, and the oxygen flow is 23000Nm³H, 15Nm of oxygen supply³/t；

Adding a second slag charge during the third top blowing; the second slag comprises second lime and first light-burned dolomite; the addition amount of the second lime is 11kg/t_Semisteel(ii) a The addition amount of the first light-burned dolomite is 7kg/t_Semisteel(ii) a The average granularity of the first light-burned dolomite is 45mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; the first light burned dolomite comprises the following components in percentage by mass: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fourth top blowing conditions are as follows: the lance position of the oxygen lance is 1.4m, and the oxygen flow is 26000Nm³H, oxygen supply 7Nm³/t；

Adding a third slag material during the fourth top blowing; the third slag comprises second light burned dolomite; the addition amount of the second light-burned dolomite is 7kg/t_Semisteel(ii) a The average granularity of the second light-burned dolomite is 45mm, and the proportion of the average granularity smaller than 5mm is less than or equal to 15 percent; in mass percentMeasured, the second lightly calcined dolomite comprises: CaO is more than or equal to 38 percent, MgO is more than or equal to 27 percent;

the fifth top blowing condition is as follows: the lance position of the oxygen lance is 1.2m, and the oxygen flow is 28000Nm³H, oxygen supply 14Nm³/t。

In this embodiment, the first lime and the second lime are CaO.

Example 4

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of converter smelting semisteel, which is the same as the embodiment 1 except that the semisteel in the step (1) is mixed with third lime with the average particle size of 8mm before being added into a hearth of the converter.

The addition amount of the third lime is 3kg/t_Semisteel(ii) a In the third lime, by mass percent: SiO 2₂2%, water content 0.3%, P0.02%, S0.06%, and the balance CaO.

Example 5

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of converter smelting semisteel, which is the same as the embodiment 1 except that the semisteel in the step (1) is mixed with third lime with the average particle size of 5mm before being added into a hearth of the converter.

The addition amount of the third lime is 2kg/t_Semisteel(ii) a In the third lime, by mass percent: SiO 2₂1% of water, 0.2% of P, 0.015% of S and the balance CaO.

Example 6

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of converter smelting semisteel, which is the same as the embodiment 1 except that the semisteel in the step (1) is mixed with third lime with the average particle size of 5mm before being added into a hearth of the converter.

The addition amount of the third lime is 4kg/t_Semisteel(ii) a In the third lime, by mass percent: SiO 2₂1.5%, water 0.4%, P0.02%, S0.04%, and the balance CaO.

Example 7

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of converter smelting semisteel, wherein first slag is first lime except for first slag and the addition amount is 12.5kg/t_SemisteelOtherwise, the same procedure as in example 1 was repeated.

Example 8

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of converter smelting semisteel, wherein the first slag material is bauxite, and the addition amount is 12.5kg/t_SemisteelOtherwise, the same procedure as in example 1 was repeated.

The bauxite described in this example was the same as the bauxite in example 1.

Example 9

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of semisteel smelted by the converter, wherein the second slag material is second lime except for 17kg/t_SemisteelOtherwise, the same procedure as in example 1 was repeated.

Example 10

Taking converter smelting HRB400E steel grade as an example, the embodiment provides a method for accelerating slagging of converter smelting semisteel, wherein a second slag material is first light-burned dolomite with the addition of 17kg/t_SemisteelOtherwise, the same procedure as in example 1 was repeated.

The first soft burned dolomite described in this example was the same as the first soft burned dolomite of example 1.

Comparative example 1

Taking converter smelting of HRB400E steel grade as an example, the comparative example provides a method for converter smelting of semisteel, which is the same as that of example 1 except that the first top-blowing is not performed.

Comparative example 2

Taking converter smelting of HRB400E steel grade as an example, the comparative example provides a method for converter smelting of semisteel, which is the same as that of example 1 except that the second top-blowing is not carried out.

Comparative example 3

Taking converter smelting of HRB400E steel grade as an example, the comparative example provides a method for converter smelting of semisteel, which is the same as that of example 1 except that the third top blowing is not carried out.

Comparative example 4

Taking converter smelting HRB400E steel grade as an example, the comparative example provides a method for smelting semisteel by using a converter, and the method is the same as that of the example 1 except that the fourth top blowing is not carried out.

The initial slag formation time, steelmaking end point temperature and end point phosphorus content of examples 1-10 and comparative examples 1-4 were measured and the results are shown in Table 1:

TABLE 1

In conclusion, the invention utilizes the characteristic that the multi-component of the raw slag is easy to melt, so that the steelmaking converter forms the initial slag as early as possible in the initial stage of blowing, the effect of accelerating slagging is achieved, and the effective dephosphorization in the early stage of blowing is realized; moreover, the method provided by the invention is suitable for the converter with the hearth temperature of less than 1000 ℃ after maintenance, and the steelmaking efficiency of the converter is ensured; the method provided by the invention is suitable for smelting semisteel by using the converter with the hearth temperature less than 1000 ℃, and has the advantages of high slagging speed and high dephosphorization efficiency.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.