CN113088800B - Method for recycling refining slag and molten steel casting residue of low-carbon aluminum killed steel LF furnace - Google Patents

Abstract

The invention belongs to the technical field of metallurgy, and relates to a method for recycling the refining slag and molten steel casting residue of a low-carbon aluminum killed steel LF furnace. The method comprises the following steps: (1) when tapping is carried out by a converter, pouring 60-70wt% of refining slag and molten steel of an upper refining furnace into a ladle waiting for tapping, and pouring the rest 30-40wt% into a slag pot; feeding an aluminum wire during argon blowing; (2) lifting the ladle to an LF refining furnace for refining, and then feeding an aluminum wire and a calcium wire; (3) hoisting the molten steel subjected to the LF refining treatment after the weak blowing to a continuous casting ladle turret to wait for casting; (4) after the ladle is cast in a continuous casting mode, 30-40% of LF refining slag in the ladle is poured into a slag tank, and the rest of LF refining slag and molten steel are poured into the next cycle. The invention ensures that the ladle has a sufficient liquid slag layer when the LF refining is in place, shortens the time of making white slag, saves the consumption of slag making materials and saves one ladle pouring process.

Description

A method for recycling slag and molten steel surplus from LF furnace refining for low carbon aluminum killed steel

technical field

The invention belongs to the technical field of metallurgy, and relates to a method for recycling slag and molten molten steel from refining slag of a low-carbon aluminum killed steel LF furnace.

Background technique

LF ladle refining furnace has a good refining effect for improving the purity of molten steel, uniformizing the composition and temperature of molten steel, and removing non-metallic inclusions in molten steel, so it is widely used in the steel smelting industry. The main principle of the LF ladle refining furnace is to use electric energy to heat and melt the flux, and use the deoxidizer to make the refining slag have a certain reducibility to promote the refining slag to deoxidize, desulfurize, and remove inclusions in the molten steel. CaO, Al in the LF refining slag The characteristics of high ₂ O ₃ content, high basicity and strong reducibility ensure the refining effect of low sulfur and low oxygen content in molten steel, and the remaining LF refining slag in the ladle after refining and casting has a strong reduction. It is a huge waste of resources and pollutes the environment. And in order to avoid slag, there will be a certain amount of molten steel in the ladle, which has a great impact on the consumption of steel materials. Therefore, it has become an urgent problem to study how to utilize the heat, reducibility, desulfurization ability and reducing efflux of LF refining slag.

The patent with the application number "CN201910256361.5" discloses a method for utilizing the hot state of LF refining top slag. The remaining molten steel and LF refining slag of continuous casting are poured into molten iron treated by KR, and then mixed into a converter for blowing. .

The patent with publication number "CN104278131A" discloses a method for recycling refining slag, which is to add refining slag to oxides such as ore, and then cool and solidify for recycling.

The invention patent with publication number CN101956043A discloses a method for recycling steelmaking residues. After the molten steel is poured, 2-3 tons of molten steel are first placed in a recovery bag, and then 2 tons of residue are poured into the recovery ladle, and a covering agent is added. 50kg. The recovered ladle is transported to the electric furnace by a transport vehicle, and the residue and molten iron are poured into the electric furnace. Since the residue is still rich in CaO, Al ₂ O ₃ and is in liquid state, it can be replaced by the electric furnace for dephosphorization and desulfurization, which reduces the amount of lime. At the same time, the heat in the residue is also effectively recycled, which reduces the consumption of the electric furnace and avoids the pollution to the environment.

The invention patent with publication number CN101403021A proposes a method for utilizing electric furnace→LF refining (VD vacuum degassing)→die casting production process to generate steel slag, adding slag-forming material in the LF ladle refining furnace and refining, adding a slag to each ton of molten steel. The slag material is 20kg-50kg, then cast, and the ladle furnace slag and remaining molten steel after casting are returned to the electric furnace for smelting, and slag-forming material is added to the electric furnace, and 50kg-70kg of slag-forming material is added per ton of molten steel. In the electric furnace smelting process, the addition of slag-forming material lime is reduced, and the power supply of the electric furnace is reduced. For steel grades that need degassing, they are refined in the LF ladle refining furnace and slag-forming materials are added. After the slagging is completed, the molten steel is sent to the VD vacuum degassing furnace for degassing, and then cast, and the ladle furnace slag and remaining molten steel are returned to the electric furnace after casting. smelting.

However, the treatment of LF ladle refining slag in the above patents is basically used in steelmaking processes such as converter, electric furnace, desulfurization pretreatment or VD. The process is long and the utilization of heat is not sufficient. The reduction and desulfurization ability of LF refining slag itself cannot be well utilized. In order to prevent sulfur enrichment, some use ore to change the characteristics and functions of LF refining slag, and finally destroy this favorable condition, and only use high alkalinity. this feature.

SUMMARY OF THE INVENTION

Aiming at the above-mentioned technical problems existing in the prior art, the present invention provides a method for recycling the refining slag and molten steel surplus of a low-carbon aluminum killed steel LF furnace.

In order to achieve the above object, the concrete technical scheme adopted in the present invention is:

A method for recycling low-carbon aluminum-killed steel LF furnace refining slag and molten steel waste, the method is suitable for the production of low-carbon aluminum-killed steel, and the composition range of molten steel: C: 0.03%-0.07%; Si: 0.015 %-0.050%; Mn: 0.16%-0.25%; S: 0.005%-0.020%; P: 0.007%-0.025%; Al: 0.016%-0.035%.

The method includes the following steps: (1) when the converter is tapping, pour the refining slag 60-70wt% of the upper refining furnace and the remaining molten steel into the ladle waiting for tapping, and pour the remaining 30-40wt% into the slag tank; immediately Open the argon blowing valve at the bottom of the ladle and let in argon; the tapping temperature of this furnace is 1600°C-1630°C; after the tapped molten steel from the converter enters the ladle for a certain period of time, silicon-manganese deoxidized alloy and quicklime are added along with the steel flow to increase the argon gas. The flow rate is stirred; after tapping, the ladle car is driven to the argon blowing position, and the aluminum wire is fed during argon blowing; (2) The ladle is lifted to the LF refining furnace for refining, and the composition temperature of the molten steel in the LF furnace is adjusted to 1580℃-1590℃ , and then after feeding the aluminum wire and calcium wire, adjust the argon flow and blow it weakly for more than 8 minutes, and the refining cycle of the LF furnace is 30min-35min; (3) Lift the molten steel that has been refined and processed by LF after weak blowing to the continuous casting ladle (4) After the continuous casting of the ladle is completed, pour 30%-40% of the LF refining slag in the ladle into the slag tank, and the remaining LF refining slag and molten steel pour into the next cycle.

Further, in step (1), the initial flow of argon is controlled at 0.2-0.4 m ³ /min, and the increased flow of argon is 2.5-3.5 m ³ /min; after tapping, the flow of argon is 1.0-1.5 m ³ /min.

Further, in step (1), 1.3-1.7 kg/t of aluminum wire is fed when blowing argon.

Further, in step (1), after the converter tapping molten steel enters the ladle for 30-40t, 1.4-1.8kg/t of silicon-manganese deoxidized alloy is added with the steel flow, and 0.8-1.5kg/t of quicklime is added according to the molten steel temperature, and the converter tapping temperature reaches 1.5kg/t quicklime was added at 1630℃, the tap temperature of the converter was 1600℃, and the quicklime added was reduced to 0.8kg/t.

Further, in step (2), the argon gas flow rate of 0.7-1.3m ³ /min is maintained during refining in the LF refining furnace, the high-grade power is sent for 7-10min, and 4.5-5.5kg/t of quicklime is added, and 0.8- 1.2kg/t.

Further, in step (2), when the S content of the refining sampling is greater than 0.025% and the aluminum content is less than 0.010%, 50-100 m of aluminum wire and 150-200 m of calcium wire are added to the ladle.

Further, in step (2), the flow rate of Ar gas is blown at the bottom of the ladle to 0.3-0.7 m ³ /min.

The advantages and positive effects that the present invention has are:

1. The present invention is a method for recycling the refining slag and molten steel of the LF furnace of low carbon aluminum killed steel, making full use of the refining conditions of the converter tapping, and advancing the refining function of a part of the LF furnace to the process of the converter tapping to complete , first pour the molten steel ladle into the slag tank after the continuous casting is completed, pour 30%-40% of the LF refining slag in the ladle into the slag tank, and pour the remaining 60%-70% of the molten LF refining slag and all the molten steel. into the ladle waiting for the converter to tap (instead of pouring it into the empty ladle); then use the ladle to pick up the molten steel for tapping, and use the heat of the molten steel at a temperature of 1600°C to 1630°C to carry out a part of the slag making process during the tapping process. And deoxidized alloying, and then to the LF furnace for refining. This process makes full use of the heat and reducibility and desulfurization ability contained in molten 60%-70% LF refining slag and molten steel continuous casting residue, so that the ladle has sufficient liquid slag layer when the LF refining is in place, and It shortens the time of making white slag, saves the consumption of slag making materials, saves electric energy, saves the consumption of electrodes, saves the consumption of alloy, and saves the process of one-time dumping.

2. Since 30%-40% of LF refining slag is excluded in each cycle, the enrichment and exclusion of harmful elements are balanced, and the accumulation of harmful elements is easily formed after multiple recycling of LF refining slag, which causes LF refining. The problem of functional weakening ensures that the LF refining slag always has an efficient refining function. At the same time, in the ladle that is recovered together with the molten steel, the process of sorting from solid slag is reduced, and the recovery rate is improved.

3. In the present invention, after the remaining 60%-70% LF refining slag and all the molten steel in the ladle are poured into the ladle, immediately open the argon blowing valve at the bottom of the ladle, and the argon gas flow is controlled at 0.3m ³ /min to prevent air-permeable bricks. Stick to cold slag or cold steel.

4. The present invention divides the refining function of the LF furnace into two stages to complete. The first step uses the converter tapping temperature heat to pre-melt a part of the flux lime, and 0.8-1.5kg/t of quicklime from the ladle is added during the converter tapping process. Therefore, The requirements for the tapping temperature of the converter: 1600℃-1630℃ to ensure the heat required for the full melting of the slag material; in the second step of the LF slagizing function, 4.5-5.5kg/t of quicklime is added to the LF furnace, and it is melted by power-on Slag making.

5. In this method, in order to further promote the slagging speed in the refining process of the LF furnace, 0.8-1.5 kg/t of high-efficiency fluorite particles are added to the LF furnace.

6. This method uses the temperature heat of the converter tapping to melt a part of the slag quicklime in advance, so that the refining start time of the molten steel is advanced before the ladle of the LF furnace is in place, so that the refining cycle of the LF furnace is shortened to 30min-35min, which saves refining time and improves the Production rhythm while saving power consumption.

7. The method of deoxidizing molten steel and refining slag in this method is mainly realized by feeding the aluminum wire of 0.8-1.5kg/t into the ladle after tapping in the converter, and feeding the molten steel in the LF refining furnace according to the aluminum content of the molten steel. Aluminum wire 50m-100m.

8. The tapping temperature of the LF furnace in this method is 1580℃-1590℃ to ensure the pourability of continuous casting.

9. This method reduces the amount of LF furnace refining slag that does not participate in the circulation to 30%-40%, and pours it into a slag tank for removal, thereby reducing environmental pollution.

Description of drawings

Fig. 1 is the schematic flow chart of the recycling utilization of the LF furnace refining slag and molten steel for the low-carbon aluminum-killed steel of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention; rather than all the embodiments. Based on the embodiments of the present invention; all other embodiments obtained by those of ordinary skill in the art without creative work; all belong to the protection scope of the present invention.

As shown in Figure 1, the present invention discloses a method for recycling low-carbon aluminum-killed steel LF furnace refining slag and molten steel surplus. : 0.03%-0.07%; Si: 0.015%-0.050%; Mn: 0.16%-0.25%; S: 0.005%-0.020%; P: 0.007%-0.025%; Al: 0.016%-0.035%.

Example 1:

This embodiment takes the 03-8903 converter as an example to carry out the following experiments:

A. Converter tapping: The composition of the converter blowing end point: C: 0.046%; Mn: 0.07%; P: 0.015%; S: 0.039%; the last furnace refining slag composition: SiO ₂ : 8.88%; MgO: 7.75%; TFe: 0.27%; Al ₂ O ₃ : 22.06%; MnO: 0.27%; binary basicity R ₂ : 6.47 times;

The following operations need to be carried out when the converter is tapping: pour about 40wt% of the refining slag from the previous furnace into the slag tank, and pour the remaining 60wt% of the refining slag and molten steel into the furnace (03-8903 furnace) 5min before the converter tapping. ) The ladle waiting for tapping; immediately open the argon blowing valve at the bottom of the ladle, and control the argon flow at 0.2m ³ /min to prevent the permeable bricks from being stuck by cold slag or cold steel, and then drive the ladle car to the converter tapping position to wait Tapping; the tapping temperature of this furnace is 1630°C; after the tapped molten steel from the converter enters the ladle for about 30t, 1.6kg/t of silicon-manganese deoxidized alloy is added with the steel flow, and 0.8-1.5kg/t of quicklime is added according to the temperature of the molten steel. When the steel temperature reaches 1630°C, add 1.5kg/t quicklime, and the converter tapping temperature is 1600°C, and add quicklime to 0.8kg/t; the argon gas flow is turned on to 2.5m ³ /min for vigorous stirring to promote the melting and encapsulation of quicklime. The bottom cold steel melts the cold slag, the alloy is uniform and the deoxidized product floats; after tapping, the ladle car is driven to the argon blowing position, the argon gas flow is adjusted to 1.0m ³ /min, and the aluminum wire is fed 1.3kg/t during argon blowing to ensure that Deoxidation of molten steel and adjustment of reducibility of top slag composition;

B. Lift the ladle to the LF refining furnace for refining. The following operations are required during refining: after blowing the slag layer with a large argon gas flow, measure the temperature and take samples, and then maintain the argon gas flow rate of 0.7m ³ /min. The hot LF refining slag and tapped liquid slag formed by adding quicklime is thick enough to transmit electricity for 7 minutes at a time, adjust the temperature for 4 minutes, and add 4.5kg/t of quicklime and 0.8kg/t of high-efficiency fluorite particles; The composition results of the sampling when the LF furnace is in place for refining, fine-tune the alloy, and decide whether to supplement the aluminum wire according to the sulfur content and aluminum content in the molten steel: when the S content of the refining sampling is 0.027%, and the aluminum content is less than 0.009%, the ladle should be supplemented. Feed 100m aluminum wire (about 0.26kg/t), and feed 150m (0.45kg/t) calcium wire after aluminum supplement to promote the denaturation of inclusions in molten steel and the floating of inclusions to be captured by LF refining slag, and improve the continuous flow of molten steel. Castability; after feeding the calcium wire, adjust the flow of Ar gas at the bottom of the ladle to 0.3m ³ /min, and perform weak blowing for 8 minutes to ensure that the ladle slag layer fluctuates slightly and the molten steel is not exposed; adjust the molten steel of the LF furnace The composition temperature reaches 1580℃, and the refining cycle is 30 minutes; the final composition of refining slag: SiO ₂ : 8.53%; CaO: 60.41%; MgO: 8.53%; TFe: 0.26%; Al ₂ O ₃ : 20.49%; MnO: 0.26% ; Binary alkalinity R ₂ : 7.08 times. Composition of molten steel: C: 0.057%; Si: 0.027%; Mn: 0.19%; P: 0.016%; S: 0.008%; Al _t : 0.022%;

C. Lift and transport the molten steel that has been refined and processed by LF after weak blowing to the turntable of the continuous casting ladle and wait for the start of pouring; after the ladle is finished casting, pour 30%-40% of the LF refining slag in the ladle. Into the slag tank, the remaining LF refining slag and molten steel pour into the next cycle.

Example 2:

This embodiment takes the 03-9229 furnace as an example to carry out the following experiments:

A. Converter tapping: composition of converter blowing end point: C: 0.039%; Mn: 0.10%; P: 0.019%; S: 0.035%. The composition of refining slag in the last furnace: SiO ₂ : 8.33%; CaO: 60.48%; MgO: 6.59%; TFe: 0.43%; Al ₂ O ₃ : 19.26%; MnO: 0.24%; binary basicity R ₂ : 7.26 times ;

The following operations need to be carried out when the converter is tapping: pour about 30wt% of the refining slag from the previous furnace into the slag tank, and pour the remaining 70wt% of the refining slag and molten steel into the furnace (03-9229 furnace) 5min before the converter tapping. ) ladle waiting for tapping; immediately open the argon blowing valve at the bottom of the ladle, and control the argon flow at 0.4m ³ /min to prevent the permeable bricks from being stuck by cold slag or cold steel, and then drive the ladle car to the converter tapping position to wait Tapping; the tapping temperature of this furnace is 1600℃; after the molten steel tapped from the converter enters the ladle for about 40t, 1.5kg/t of silicon-manganese deoxidized alloy is added with the steel flow, and 0.8-1.5kg/t of quicklime is added according to the temperature of the molten steel. When the steel temperature reaches 1630°C, add 1.5kg/t quicklime, and the converter tapping temperature is 1600°C, and add quicklime to 0.8kg/t; the argon gas flow is turned on to 3.5m ³ /min for vigorous stirring to promote the melting and encapsulation of quicklime. The bottom cold steel melts the cold slag, the alloy is uniform and the deoxidized product floats; after tapping, the ladle car is driven to the argon blowing position, the argon gas flow is adjusted to 1.5m ³ /min, and the aluminum wire is fed 1.7kg/t during argon blowing to ensure Deoxidation of molten steel and adjustment of reducibility of top slag composition;

B. Lift the ladle to the LF refining furnace for refining. The following operations are required during refining: after blowing the slag layer with a large argon gas flow, measure the temperature and take samples, and then maintain the argon gas flow rate of 1.3m ³ /min. The hot LF refining slag and tapped liquid slag formed by adding quicklime is thick enough to transmit electricity for 10 minutes at a time, adjust the temperature for 3 minutes, and add 5.5kg/t of quicklime and 1.2kg/t of high-efficiency fluorite particles; and According to the sulfur content and aluminum content in the molten steel, it is decided whether to supplement the aluminum wire: when the S content of the refining sampling is 0.026% and the aluminum content is 0.008%, the LF refining supplements the aluminum wire for 50m (about 0.26kg/t), and feeds the calcium wire for 200m. (0.6kg/t); after feeding the calcium wire, adjust the flow of Ar gas at the bottom of the ladle to 0.7m ³ /min, and carry out weak blowing for 10 minutes to ensure that the ladle slag layer fluctuates slightly and the molten steel is not exposed as a principle; adjust the LF furnace The composition temperature of molten steel reaches 1590°C, and the refining cycle is 35 minutes; the final composition of refining slag: SiO ₂ : 9.08%; CaO: 55.91%; MgO: 7.77%; TFe: 0.31%; Al ₂ O ₃ : 20.87%; MnO: 0.25 %; binary basicity R ₂ : 6.16 times. Molten steel composition: C: 0.047%; Si: 0.037%; Mn: 0.19%; P: _0.021 %; S: 0.013%;

C. Lift and transport the molten steel that has been refined and processed by LF after weak blowing to the turntable of the continuous casting ladle and wait for the start of pouring; after the ladle is finished casting, pour 30%-40% of the LF refining slag in the ladle. Into the slag tank, the remaining LF refining slag and molten steel pour into the next cycle.

The invention is a method for recycling slag refining slag and molten molten steel of low-carbon aluminum killed steel LF furnace, making full use of the refining conditions of converter tapping, and advancing a part of the refining function of the LF furnace to the process of converter tapping to complete the process. After the continuous casting of the ladle is completed, 30%-40% of the LF refining slag in the ladle is poured into the slag tank, and the remaining 60%-70% of the molten LF refining slag and all the molten steel are poured and waited. In the ladle of the converter tapping (instead of pouring it into an empty ladle); then use the ladle to pick up the molten steel, and use the heat of the molten steel at a temperature of 1600 ° C - 1630 ° C to carry out part of the slagging process and deoxidation during the tapping process. Alloying before going to the LF furnace for refining. This process makes full use of the heat and reducibility and desulfurization ability contained in molten 60%-70% LF refining slag and molten steel continuous casting residue, so that the ladle has sufficient liquid slag layer when the LF refining is in place, and It shortens the time of making white slag, saves the consumption of slag making materials, saves electric energy, saves the consumption of electrodes, saves the consumption of alloy, and saves the process of one-time dumping.

Since 30%-40% of LF refining slag is excluded in each cycle, the enrichment and exclusion of harmful elements are balanced, which solves the problem that the enrichment of harmful elements is easily formed after the LF refining slag is recycled for many times, and the LF refining function is weakened. , which ensures that the LF refining slag always has an efficient refining function. At the same time, in the ladle that is recovered together with the molten steel, the process of sorting from solid slag is reduced, and the recovery rate is improved.

The embodiments of the present invention have been described in detail above, but the content described above is only a preferred embodiment of the present invention, and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope of the patent of the present invention.

Claims (4)

1. A method for recycling refining slag and molten steel casting residue of a low-carbon aluminum killed steel LF furnace is applicable to the low-carbon aluminum killed steel and comprises the following components: 0.03% -0.07%; si: 0.015% -0.050%; mn: 0.16% -0.25%; s: 0.005% -0.020%; p: 0.007% -0.025%; al: 0.016% -0.035%; the method is characterized in that:

the method comprises the following steps: (1) when tapping is carried out by a converter, pouring 60-70wt% of refining slag and the rest of molten steel of the refining slag of an upper refining furnace into a ladle waiting for tapping, and pouring the rest 30-40wt% of refining slag into a slag pot; opening a ladle bottom argon blowing valve immediately and introducing argon; the tapping temperature of the furnace is 1600-1630 ℃; after molten steel discharged from the converter enters a steel ladle for a certain time, adding silicomanganese deoxidized alloy and quicklime along with the molten steel, and increasing argon flow for stirring; after tapping, driving the ladle car to an argon blowing position, and feeding an aluminum wire during argon blowing; (2) lifting the ladle to an LF refining furnace for refining, adjusting the component temperature of molten steel in the LF furnace to 1580-1590 ℃, then feeding an aluminum wire and a calcium wire, adjusting the flow of argon and weakly blowing for more than 8 minutes, and keeping the refining period of the LF furnace for 30-35 min; (3) hoisting the molten steel subjected to the LF refining treatment after the weak blowing to a continuous casting ladle turret to wait for casting; (4) after the ladle is cast in a continuous casting mode, 30-40% of LF refining slag in the ladle is poured into a slag tank, and the rest of LF refining slag and molten steel are poured into the next cycle;

the initial flow of argon in the step (1) is controlled to be 0.2-0.4m ³ Min, increased argon flow rate of 2.5-3.5m ³ Min; the argon flow is 1.0-1.5m after tapping ³ /min；

After molten steel discharged from a converter in the step (1) enters a steel ladle for 30-40t, adding 1.4-1.8kg/t of silicon-manganese deoxidized alloy along with the steel flow, adding 0.8-1.5kg/t of quicklime according to the temperature of the molten steel, adding 1.5kg/t of quicklime when the tapping temperature of the converter reaches 1630 ℃, reducing the adding amount of the quicklime to 0.8kg/t when the tapping temperature of the converter is 1600 ℃, and increasing the adding amount of the quicklime by 0.1kg/t when the tapping temperature rises by 4 ℃;

keeping the refining time of the LF refining furnace in the step (2) to be 0.7-1.3m ³ Argon flow per min, high-level power transmission for 7-10min, quick lime 4.5-5.5kg/t and efficient fluorite particles 0.8-1.2 kg/t.

2. The method for recycling the refining slag and the molten steel casting residue of the low-carbon aluminum killed steel LF furnace as claimed in claim 1, wherein: feeding 1.3-1.7kg/t of aluminum wire during argon blowing in the step (1).

3. The method for recycling the refining slag and the molten steel casting residue of the low-carbon aluminum killed steel LF furnace as claimed in claim 1, wherein: when the S content of the refining sample in the step (2) is more than 0.025 percent and the aluminum content is less than 0.010 percent, a 50-100m aluminum wire is fed into a ladle, and a 150-200m calcium wire is fed into the ladle.

4. The method for recycling the refining slag and the molten steel casting residue of the low-carbon aluminum killed steel LF furnace as claimed in claim 1, wherein: in the step (2), the flow of Ar gas blown from the bottom of the ladle is 0.3-0.7m ³ /min。

Images