Semi-steel steelmaking less-slag smelting method

Abstract

The invention discloses a semi-steel steelmaking less-slag smelting method. The method comprises the following steps that S1, slag is completely left and splashed after smelting of steel on a furnace is finished; s2, adding quartz sand, a slag melting agent and waste steel into the converter, adding iron, blowing the converter without adding high-magnesium lime and active lime, blowing, and slagging; s3, secondary slagging is carried out after slagging, the oxygen flow is increased, meanwhile, high-magnesium lime and active lime are added into the converter, the end point carbon and temperature of the converter are controlled according to the steel grade tapping requirement, and tapping is directly carried out after blowing is finished without slagging; and S4, after tapping, all slag is left and splashed, according to the steel grade, the steel phosphorus requirement is judged, the number of times of recycling of the remaining slag of the semi-steel steelmaking furnace slag and the slag remaining amount are set, and then the step S2 and the step S3 are repeated. According to the method, low-temperature and low-alkalinity operation is adopted in the early stage of semisteel smelting, and a secondary slagging high-temperature and high-alkalinity operation process in the later stage is adopted, so that the overall dephosphorization capacity of the semisteel steelmaking slag is improved, the slag consumption of the semisteel steelmaking converter is effectively reduced, and obvious economic and technical benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a semi-steelmaking and low-slag smelting method. Background Art

[0002] my country has rich vanadium-titanium magnetite resources. Domestic steel enterprises that develop and utilize vanadium-titanium magnetite resources, such as Panzhihua Iron and Steel, Chengde Iron and Steel, Kunming Iron and Steel, and Weigang, all use semi-steel steelmaking after vanadium is extracted from vanadium-containing hot metal converters. The carbon mass percentage of semi-steel after vanadium is extracted from vanadium-containing hot metal is 3.2%~3.8%, and the content of silicon and manganese in the semi-steel is trace elements of heat-generated slag, and the phosphorus mass percentage is 0.060%~0.085%. Therefore, semi-steel smelting has the characteristics of less acidic slag-forming substances in the blowing process, single slag system components, insufficient heat, long initial slag slag time, low dephosphorization rate and large auxiliary material consumption. Therefore, it is particularly necessary to achieve less slag smelting in semi-steel steelmaking.

[0003] In view of this, the existing technology should be improved. Summary of the invention

[0004] The main purpose of the present invention is to provide a low-slag smelting method for semi-steel steelmaking. In view of the characteristics of long initial slag formation time, low dephosphorization rate and large auxiliary material consumption in the semi-steel smelting blowing process, low-temperature and low-basicity operation is adopted in the early stage of semi-steel smelting, and high-temperature and high-basicity operation process is adopted in the later secondary slag making, which improves the overall dephosphorization capacity of the semi-steel steelmaking furnace slag, effectively reduces the slag consumption of the semi-steel steelmaking converter, and has obvious economic and technical benefits.

[0005] According to one aspect of the present invention, a semi-steel steelmaking low-slag smelting method is provided, which comprises the following steps: S1. After the steel smelting is completed, all slag is left and splashed; S2. After the slag splashing, quartz sand, slag-removing agent and scrap steel are added to the converter in each furnace, and then iron is added. The converter starts blowing at the first gun position, and is lowered to the second gun position 0~1min before the furnace is turned over and the slag is discharged. The oxygen flow rate is 26000~28000 m³ / h, and the bottom blowing gas supply single brick flow rate is 1400~1600NL / min. The slag is discharged after blowing for 1~3min; S3, after slag discharge, secondary slag making is carried out, and the oxygen flow rate is increased. At the same time, high magnesium lime and active lime are added to the converter furnace in each furnace. The final carbon and final temperature of the converter are controlled according to the steel grade tapping requirements. After the blowing is completed, no slag is discharged and steel is tapped directly; S4, after steel is tapped, all slag is retained and slag splashing is avoided, and the steel phosphorus demand is determined according to the steel type, and the number of slag recycling times and the amount of slag retained by the semi-steel steelmaking furnace are set, and then steps S2 and S3 are repeated.

[0006] According to one embodiment of the present invention, in step S4, judging the steel phosphorus demand according to the steel type and setting the number of slag recycling times and the amount of slag left in the semi-steel steelmaking furnace slag include: For steels with phosphorus content ≤ 0.015%, after the converter is finished tapping, all slag is left until the second furnace is smelted, and 3 to 5 tons of slag is left after tapping, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.015%<and ≤0.020%, after the converter is finished with steel, all slag is retained until the third furnace is smelted, and 4 to 7 tons of slag is retained after steel is tapped, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.020%<and ≤0.025%, after the converter is finished with steel, all slag is retained until the third furnace is smelted, and 5 to 8 tons of slag is retained after steel is tapped, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.025%<and ≤0.035%, after the steel is discharged from the converter, all slag is retained and smelted for 4 furnaces. At the end of steel discharge, 6 to 10 tons of slag is retained and a new round of full slag cycle smelting begins.

[0007] According to one embodiment of the present invention, in step S1, the amount of quartz sand added is 600kg~800kg, the amount of slag-removing agent added is 0~200kg, and the amount of scrap steel added is 5~12t.

[0008] According to one embodiment of the present invention, in step S1, the slag basicity is controlled to be between 1.6 and 2.0.

[0009] According to one embodiment of the present invention, in step S2, the first gun position is 1.5-1.6 m, and the second gun position is 1.2-1.3 m.

[0010] According to one embodiment of the present invention, in step S2, the slag tapping temperature is controlled at 1350-1400°C, and the bottom blowing flow rate during slag tapping is adjusted to a basic flow rate of 45-55NL / min.

[0011] According to one embodiment of the present invention, in step S2, the slag discharge amount accounts for 45-55% of the total slag amount.

[0012] According to one embodiment of the present invention, in step S3, the oxygen flow rate is increased to 30000-31000 m³ / h.

[0013] According to one embodiment of the present invention, the amount of high-magnesium lime added is 1300-1500 kg, and the amount of active lime added is 1300-1500 kg.

[0014] According to one embodiment of the present invention, the secondary slag making controls the slag basicity to be between 3.0 and 3.5.

[0015] In a semi-steel steelmaking low-slag smelting method according to an embodiment of the present invention, in view of the characteristics of long initial slag formation time, low dephosphorization rate, and large auxiliary material consumption in the semi-steel smelting blowing process, low temperature (1350~1400℃) and low basicity (1.6~2.0) operation are adopted in the early stage of semi-steel smelting, and high temperature (1640~1660℃) and high basicity (3.0~3.5) operation process are adopted in the later secondary slag making, which improves the overall dephosphorization capacity of the semi-steel steelmaking slag, effectively reduces the slag material consumption of the semi-steel steelmaking converter, has obvious economic and technical benefits, and can reduce auxiliary material consumption, reduce slag generation, and alleviate subsequent processing pressure through slag retention circulation and optimization of converter smelting parameters, and can also improve metal recovery rate, improve economic benefits, and reduce energy consumption, making the steelmaking process more efficient and reducing overall costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings required for use in the embodiment will be briefly introduced below. Obviously, the drawings described below are only some implementation cases of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A process flow chart of a semi-steelmaking and low-slag smelting method according to an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0018] The detailed description of the following embodiments is used to exemplify the principles of the present invention, but cannot be used to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0019] The present invention provides these embodiments to make this disclosure thorough and complete, and fully express the scope of the present invention to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the parts and steps, the composition of materials, numerical expressions and numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary, rather than as limiting.

[0020] It should be noted that, in the description of the present invention, unless otherwise specified, the meaning of "multiple" is greater than or equal to two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating the orientation or positional relationship, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0021] It should also be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. When a specific device is described as being located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device.

[0022] All terms used in the present invention have the same meanings as those understood by those of ordinary skill in the art to which the present disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries, for example, should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined herein.

[0023] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, these technologies, methods, and equipment should be considered part of the specification.

[0024] like Figure 1 As shown, the present invention provides a semi-steel steelmaking low-slag smelting method, which comprises the following steps: S1. After the steel smelting is completed, all slag is left and splashed; S2. After the slag splashing, quartz sand, slag-removing agent and scrap steel are added to the converter in each furnace, and then iron is added. The converter starts blowing at the first gun position, and is reduced to the second gun position 0~1min before the furnace is turned over and the slag is discharged. The oxygen flow rate is 26000~28000 m³ / h, and the bottom blowing gas supply single brick flow rate is 1400~1600NL / min. After blowing, high magnesium lime and active lime are no longer added, and the slag is discharged after blowing for 1~3min; S3, after slag discharge, secondary slag making is carried out, and the oxygen flow rate is increased. At the same time, high magnesium lime and active lime are added to the converter furnace in each furnace. The final carbon and final temperature of the converter are controlled according to the steel grade tapping requirements. After the blowing is completed, no slag is discharged and steel is tapped directly; S4, after steel is tapped, all slag is retained and slag splashing is avoided, and the steel phosphorus demand is determined according to the steel type, and the number of slag recycling times and the amount of slag retained by the semi-steel steelmaking furnace are set, and then steps S2 and S3 are repeated.

[0025] In some embodiments, the furnace is lowered to the second gun position 1 minute before slag discharge, the oxygen flow rate is 28000 m³ / h, the bottom blowing gas supply single brick flow rate is 1500NL / min, and the slag is discharged after 2 minutes of blowing.

[0026] In the semi-steel steelmaking low-slag smelting method according to an embodiment of the present invention, in view of the characteristics of long initial slag formation time, low dephosphorization rate and large auxiliary material consumption in the semi-steel smelting blowing process, low temperature (1350~1400℃) and low basicity (1.6~2.0) operation are adopted in the early stage of semi-steel smelting, and high temperature (1640~1660℃) and high basicity (3.0~3.5) operation process of secondary slag making in the later stage are adopted, which improves the overall dephosphorization capacity of the semi-steel steelmaking slag, effectively reduces the consumption of semi-steel steelmaking converter slag, and has obvious economic and technical benefits.

[0027] In some specific embodiments, in step S4, determining the steel phosphorus demand according to the steel type and setting the number of slag recycling times and the amount of slag left in the semi-steel steelmaking furnace slag include: For steels with phosphorus content ≤ 0.015%, after the converter is finished tapping, all slag is left until the second furnace is smelted, and 3 to 5 tons of slag is left after tapping, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.015%<and ≤0.020%, after the converter is finished with steel, all slag is retained until the third furnace is smelted, and 4 to 7 tons of slag is retained after steel is tapped, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.020%<and ≤0.025%, after the converter is finished with steel, all slag is retained until the third furnace is smelted, and 5 to 8 tons of slag is retained after steel is tapped, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.025%<and ≤0.035%, after the steel is discharged from the converter, all slag is retained and smelted for 4 furnaces. At the end of steel discharge, 6 to 10 tons of slag is retained and a new round of full slag cycle smelting begins.

[0028] According to the requirements of the steel grade for phosphorus content, different slag retention recycling times can be set. For steel grades with low phosphorus content requirements, the recycling times of slag can be appropriately increased to improve dephosphorization efficiency; while for steel grades with very strict phosphorus content requirements, the recycling times of slag need to be carefully controlled to avoid the accumulation of phosphorus.

[0029] The amount of slag retention will also affect the dephosphorization effect. Appropriate slag retention can provide sufficient dephosphorization reaction interface to promote the removal of phosphorus; but excessive slag retention may cause phosphorus in the slag to re-enter the molten steel, so it needs to be set according to the specific steel grade and smelting conditions.

[0030] In some specific embodiments, in step S1, the amount of quartz sand added is 600kg~800kg, the amount of slag-removing agent added is 0~200kg, and the amount of scrap steel added is 5~12t.

[0031] Based on the above embodiment, in step S1, the slag basicity is controlled at 1.6-2.0.

[0032] In some specific embodiments, in step S2, the first gun position is 1.5-1.6 m, and the second gun position is 1.2-1.3 m. Specifically, the second gun position is 1.3 m.

[0033] Lowering the lance position means that the oxygen lance is closer to the surface of the molten pool, the impact force of the oxygen flow on the molten pool is increased, and the impact depth is deeper. This strong stirring effect helps to promote chemical reactions in the molten pool, especially decarburization reactions, so that the molten pool is more fully stirred. This is conducive to the melting of scrap steel and the uniform distribution of various components in the molten pool, avoiding the appearance of "dead zones", thereby indirectly increasing the melting rate and terminal temperature of scrap steel.

[0034] Based on the above embodiment, in step S2, the slag tapping temperature is controlled at 1350-1400°C, and the bottom blowing flow rate is adjusted to a basic flow rate of 45-55 NL / min during slag tapping. Specifically, the bottom blowing flow rate is adjusted to a basic flow rate of 50 NL / min.

[0035] When the bottom blowing flow rate is too large, a large number of small bubbles float up into the slag, which may cause serious emulsification of the slag. The emulsified slag may enter the molten steel under the action of the liquid flow, forming new inclusions and reducing the quality of the molten steel. Reducing the bottom blowing flow rate can reduce the generation of small bubbles, thereby reducing the risk of slag emulsification and maintaining the purity of the molten steel.

[0036] In some specific embodiments, in step S2, the amount of slag discharge accounts for 45-55% of the total slag amount. Specifically, the amount of slag discharge accounts for 50% of the total slag amount.

[0037] Based on the above embodiment, in step S3, the oxygen flow rate is increased to 30000-31000 m³ / h. Specifically, the oxygen flow rate is increased to 30000 m³ / h.

[0038] Increasing the oxygen flow rate can significantly enhance the stirring effect of the molten pool. Oxygen is sprayed into the molten pool at high speed through the spray gun, producing a strong stirring effect, so that the molten steel and slag in the molten pool are fully mixed. This mixing effect helps to accelerate the rate of chemical reactions and improve smelting efficiency.

[0039] In the secondary slag-making stage, increasing the oxygen flow rate can promote a series of chemical reactions. For example, oxygen can react with carbon in the molten pool to produce carbon monoxide and carbon dioxide, thereby releasing heat and accelerating the decarburization process. In addition, oxygen can also react with certain components in the slag, such as iron oxide, to help adjust the composition and properties of the slag.

[0040] In some specific embodiments, the amount of high-magnesium lime added is 1300-1500 kg, and the amount of active lime added is 1300-1500 kg.

[0041] On the basis of the above embodiments, the secondary slag making controls the slag basicity to be between 3.0 and 3.5.

[0042] By properly controlling the slag basicity, the chemical reaction rate in the smelting process can be optimized. For example, in the steelmaking process, appropriate slag basicity helps to accelerate key reactions such as decarbonization, dephosphorization and desulfurization, thereby improving smelting efficiency, which can not only shorten the smelting cycle, but also reduce energy consumption and production costs.

[0043] The present invention adopts a phased operation strategy to address the problems of long initial slag formation time, low dephosphorization efficiency, and significant auxiliary material consumption in the semi-steel smelting and blowing process. In the early stage of semi-steel smelting, a low-temperature and low-alkalinity operation process is implemented to optimize the reaction conditions in the early stage of smelting; in the later stage, secondary slag making technology is used to significantly enhance the overall dephosphorization capacity of the slag by increasing the temperature and alkalinity. This strategy not only effectively shortens the initial slag formation time, but also greatly improves the dephosphorization efficiency and significantly reduces the consumption of converter slag in the semi-steel steelmaking process. Therefore, the implementation of the present invention brings significant economic and technical benefits, and provides strong support for energy conservation, emission reduction and efficient production in the semi-steel smelting industry.

[0044] Example 1 Common carbon steel smelting with phosphorus content ≤ 0.035% S1: After the steel is smelted, all slag is left and splashing; S2. After the slag splashing, quartz sand, slag-removing agent and scrap steel are added to the converter, and then iron is added. The converter is opened at the first gun position, and is lowered to the second gun position 1 minute before the furnace is turned over and the slag is discharged. The oxygen flow rate is 2700 m³ / h, and the bottom blowing gas supply single brick flow rate is 1500NL / min. No high-magnesium lime and active lime are added after the blowing, and the slag is discharged after 2.5 minutes of blowing; S3, after slag discharge, secondary slag making is carried out, and the oxygen flow rate is increased. At the same time, high magnesium lime and active lime are added to the converter furnace in each furnace. The final carbon and final temperature of the converter are controlled according to the steel grade and steel tapping requirements. After the blowing is completed, no slag is discharged and steel is tapped directly; S4: After the converter taps out steel, all slag is retained (6-10t, with an average slag retention of 8.5t) and slag splashing is performed. After smelting 4 batches of steel in a cycle, steps S2 and S3 are repeated.

[0045] Results: The consumption of slag for smelting one ton of carbon steel and semi-steel in converter with phosphorus content ≤ 0.035% is only 35 kg, which is 5.2 kg less than that of the same type of process.

[0046] Example 2 Determine the steel phosphorus content ≤ 0.015% of the beam steel smelting S1: After the steel smelting is completed, slag is left (3-5t, average 4.2t) and slag splashing; S2. After the slag splashing, quartz sand, slag-removing agent and scrap steel are added to the converter, and then iron is added. The converter is opened at the first gun position, and is lowered to the second gun position 0.5min before the furnace is turned over and the slag is discharged. The oxygen flow rate is 30000 m³ / h, and the bottom blowing gas supply single brick flow rate is 1800NL / min. No high magnesium lime and active lime are added after the blowing, and the slag is discharged after 3min of blowing. S3, after slag discharge, secondary slag making is carried out, and the oxygen flow rate is increased. At the same time, high magnesium lime and active lime are added to the converter furnace in each furnace. The final carbon and final temperature of the converter are controlled according to the steel grade and steel tapping requirements. After the blowing is completed, no slag is discharged and steel is tapped directly; S4: After the converter taps out steel, slag (3-5t, 4.4t on average) is left and slag splashing is performed. After smelting two batches of steel in a cycle, steps S2 and S3 are repeated.

[0047] Results: The consumption of semi-steel converter smelting ton of steel slag for beam steel with phosphorus content ≤ 0.015% is only 37.6 kg, which is 4.3 kg less than that of the same type of process.

[0048] The above are exemplary embodiments disclosed in the present invention. The order disclosed in the above embodiments of the present invention is for description only and does not represent the advantages and disadvantages of the embodiments. However, it should be noted that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope disclosed in the embodiments of the present invention (including the claims) is limited to these examples. Various changes and modifications may be made without departing from the scope defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0049] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A semi-steel steelmaking low-slag smelting method, characterized in that: The following steps are involved: S1. After the steel smelting is completed, all slag is left and splashed; S2. After the slag splashing, quartz sand, slag-removing agent and scrap steel are added to the converter in each furnace, and then iron is added. The converter starts blowing at the first gun position, and is lowered to the second gun position 0~1min before the furnace is turned over and the slag is discharged. The oxygen flow rate is 26000~28000m³ / h, and the bottom blowing gas supply single brick flow rate is 1400~1600NL / min. The slag is discharged after blowing for 1~3min; S3, after slag discharge, secondary slag making is carried out, and the oxygen flow rate is increased. At the same time, high magnesium lime and active lime are added to the converter furnace in each furnace. The final carbon and final temperature of the converter are controlled according to the steel grade tapping requirements. After the blowing is completed, no slag is discharged and steel is tapped directly; S4, after steel is tapped, all slag is retained and slag splashing is avoided, and the steel phosphorus demand is determined according to the steel type, and the number of slag recycling times and the amount of slag retained by the semi-steel steelmaking furnace are set, and then steps S2 and S3 are repeated.

2. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: In step S4, the step of determining the phosphorus demand of steel according to the steel type and setting the number of slag recycling times and the amount of slag left in the semi-steel steelmaking furnace slag includes: For steels with phosphorus content ≤ 0.015%, after the converter is finished tapping, all slag is left until the second furnace is smelted, and 3 to 5 tons of slag is left after tapping, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.015%<and ≤0.020%, after the converter is finished with steel, all slag is retained until the third furnace is smelted, and 4 to 7 tons of slag is retained after steel is tapped, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.020%<and ≤0.025%, after the converter is finished with steel, all slag is retained until the third furnace is smelted, and 5 to 8 tons of slag is retained after steel is tapped, and a new round of full slag cycle smelting begins; For steels with phosphorus content of 0.025%<and ≤0.035%, after the steel is discharged from the converter, all slag is retained and smelted for 4 furnaces. At the end of steel discharge, 6 to 10 tons of slag is retained and a new round of full slag cycle smelting begins.

3. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: In step S1, the amount of quartz sand added is 600kg~800kg, the amount of slag-removing agent added is 0~200kg, and the amount of scrap steel added is 5~12t.

4. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: In step S1, the slag basicity is controlled at 1.6-2.

0.

5. The semi-steelmaking low-slag smelting method according to claim 4, characterized in that: In step S2, the first gun position is 1.5-1.6 m, and the second gun position is 1.2-1.3 m.

6. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: In step S2, the slag tapping temperature is controlled at 1350-1400°C, and the bottom blowing flow rate is adjusted to a basic flow rate of 45-55NL / min during slag tapping.

7. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: In step S2, the slag discharge amount accounts for 45-55% of the total slag amount.

8. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: In step S3, the oxygen flow rate is increased to 30000-31000 m³ / h.

9. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: The amount of high-magnesium lime added is 1300-1500kg, and the amount of active lime added is 1300-1500kg.

10. The semi-steelmaking low-slag smelting method according to claim 1, characterized in that: The secondary slag making controls the slag basicity to be between 3.0 and 3.5.

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