阅读说明：本技术 能减少出钢过程中下渣量的凸腔型转炉及出钢工艺 (Convex cavity type converter capable of reducing slag discharge amount in tapping process and tapping process ) 是由 王博 白星良 张东峰 王鹏飞 韩道刚 王鸿雁 于 2020-07-07 设计创作，主要内容包括：本发明涉及一种能减少出钢过程中下渣量的凸腔型转炉及出钢工艺,属于钢铁冶金技术领域。包括转炉,转炉上部设有出钢口,出钢口由转炉内腔外凸形成椭锥形凸腔体。本发明凸腔体连通出钢口和炉体,出钢口上方形成一个液位较高的熔池,在出钢流注速不变的情况下,能够抑制涡流的生成,减小下渣量。(The invention relates to a convex cavity type converter capable of reducing slag discharge in a tapping process and a tapping process, and belongs to the technical field of ferrous metallurgy. Comprises a converter, wherein the upper part of the converter is provided with a steel tapping hole, and the steel tapping hole is protruded from the inner cavity of the converter to form an elliptic cone-shaped convex cavity. The convex cavity is communicated with the steel tapping hole and the furnace body, a molten pool with higher liquid level is formed above the steel tapping hole, and under the condition that the pouring speed of the steel tapping flow is not changed, the generation of vortex can be inhibited, and the slag discharging amount is reduced.)

1. A convex cavity type converter capable of reducing the slag discharge in the tapping process comprises a converter (1), wherein a tapping hole (5) is formed in the upper portion of the converter (1), and the convex cavity is characterized in that the tapping hole (5) is formed in a mode that an inner cavity of the converter (1) protrudes outwards to form an elliptic conical convex cavity (4).

2. The convex cavity type converter according to claim 1, wherein the convex cavity (4) is formed to extend outward along the axis of the tap hole (5).

3. The convex-cavity converter capable of reducing the slag discharge amount in the tapping process as claimed in claim 1, wherein the convex cavity (4) intersects with the side wall of the inner cavity of the converter (1) to form a convex cavity bottom surface a, the bottom surface a is a curved surface, and the bottom surface a projects to a maximum area s; the vertex D of the convex cavity (4) is connected with the inner hole of the pipeline of the steel tapping hole (5), and the distance between the vertex D and the maximum projection area s is the depth h of the convex cavity.

4. The convex cavity type converter capable of reducing the amount of slag discharged during tapping according to claim 3, wherein the converter (1) has a nominal capacity of 100t to 300t and the depth h of the convex cavity (4) is 0.4m to 0.8 m.

5. Convex chamber converter with reduced tapping according to claim 3, characterized in that the nominal capacity of the converter (1) is 100t-300t and the volume v of the convex chamber (4) is 1.5-3.0m³。

6. The convex cavity type converter capable of reducing the amount of slag discharged during tapping according to claim 1, wherein the converter (1) has a nominal capacity of 100t-300t and the diameter of the tap hole (5) is enlarged by 10% -20%.

7. A convex cavity type converter tapping process capable of reducing the slag discharge amount in the tapping process is characterized by comprising the following steps:

(1) before smelting, a slag blocking cap is arranged from the steel tapping hole (5);

(2) tapping: the steel tapping hole (5) protrudes outwards towards the inner cavity of the converter (1) to form an elliptic conical convex cavity (4), and the convex cavity (4) extends outwards along the axis of the steel tapping hole (5);

1) starting a rocking furnace: the instant slag and the molten steel (2) flow from the convex cavity body (4) to the steel tapping hole (5), and the slag blocking cap effectively blocks the instant slag to avoid initial slag dropping;

2) and (3) beginning tapping: the inclination angle of the converter (1) is 75-85 degrees, and the molten steel (2) passes through the convex cavity (4) and is discharged to the steel outlet (5);

3) in the middle stage of tapping: the inclination angle of the converter (1) is 85-95 degrees, full flow is kept in the convex cavity (4), the depth of a molten pool is at least the depth h of the convex cavity (4), vortex production is effectively inhibited, and the slag discharge caused by vortex slag entrapment is reduced;

4) and (3) in the later tapping stage: the inclination angle of the converter (1) is 95-105, the slag blocking ball or the slag blocking cone is thrown into the converter (1), the molten steel (2) is reduced, the liquid level of the molten steel (2) gradually drops into the convex cavity (4), the convex cavity (4) guides the slag blocking ball or the slag blocking cone, the slag blocking ball or the slag blocking cone is pushed to accurately move towards the steel tapping hole (5), vortex formation is effectively interfered, and the slag discharging amount in the later tapping period is reduced.

8. The convex-cavity converter tapping process capable of reducing the slag discharge amount in the tapping process according to claim 7, wherein the convex cavity (4) is intersected with the side wall of the inner cavity of the converter (1) to form a convex cavity bottom surface a, the bottom surface a is a curved surface, and the maximum area s of the projection of the bottom surface a is larger than the maximum area s of the projection of the bottom surface a; the vertex D of the convex cavity (4) is connected with the inner hole of the pipeline of the steel tapping hole (5), and the distance between the vertex D and the maximum projection area s is the depth h of the convex cavity.

9. The tapping process of a convex cavity type converter capable of reducing the amount of slag discharged during tapping according to claim 8, characterized in that the nominal capacity of the converter (1) is 100t-300t and the depth h of the convex cavity (4) is 0.4m-0.8 m.

Technical Field

The invention relates to a convex cavity type converter capable of reducing slag discharge in a tapping process and a tapping process, and belongs to the technical field of ferrous metallurgy.

Background

The effective slag-stopping operation is carried out during the tapping of the converter, is an important means for improving the quality of molten steel, can reduce the consumption of deoxidizer and alloy, reduce the rephosphorization of the molten steel, reduce inclusions in the steel, improve the cleanliness of the molten steel and provide good conditions for refining the molten steel. In addition, the effective slag blocking operation can reduce slag adhesion of the steel ladle, prolong the service life of the steel ladle, improve the service life of refractory materials at a steel tapping hole of the converter and effectively reduce the production cost. Therefore, as an iron and steel enterprise, reducing the slag discharge amount of converter tapping is the most effective way for improving the quality and grade of steel products and reducing the production cost, and converter tapping and slag stopping are always a technical problem facing steel mills at home and abroad.

The current mainstream slag stopping methods comprise:

(1) and in the slag ball blocking method, the density of slag balls is between 4.2 and 4.5g/cm of slag steel, and a steel tapping hole is blocked when tapping is finished so as to prevent converter slag from entering a steel ladle. Its advantages are simple operation and low cost. Considering the problem that the steel tapping hole is enlarged in the later use period, the diameter of the slag stopping ball is larger than that of the steel tapping hole. However, the steel grades being smelted are also changed frequently due to different raw material conditions, which results in different viscosity of the steel slag. Because the slag stopping ball moves to the steel tapping hole along with the vortex in the converter, when the viscosity of the steel slag is high, the slag stopping ball is difficult to reach the steel tapping hole, and the slag stopping efficiency is low. Moreover, the slag trap ball blocks the tap hole too early if the molten steel is not completely drained, which reduces the yield of the molten steel.

(2) The slag blocking plug method has the advantages that the device is in a top shape with a guide rod at the lower part, three grooves are formed at the thick end, compared with a slag blocking ball, the specific gravity can be flexibly adjusted, the preset position can be automatically and accurately reached, the dual functions of vortex suppression and slag blocking are achieved, and the slag blocking rate is about 95%.

(3) The slag-stopping method is to change the flowability of converter slag, i.e. to spray a solid mixture to the slag at the end of converter blowing to increase the consistency of the slag. The slag is partially or completely condensed, or granular refractory material is put on the slag surface at the upper part of the tap hole to form a block-shaped plug, so that the slag is prevented from flowing out. The method has certain effect on stopping slag during tapping, but has large material consumption and is not beneficial to slag splashing and furnace protection.

(4) The slag-avoiding cover method is to build a slag-avoiding cover towards the steel tapping hole. When tapping, the molten steel flows into the tapping hole through the side hole of the slag avoiding cover made of refractory material. The top of the slag-avoiding cover is in a closed form, so that the formation of vortex below the steel-tapping hole is hindered, the vortex is effectively prevented from rolling slag, and the effect of slag stopping and steel tapping is achieved. However, the slag-blocking method is troublesome to operate, consumes large refractory materials, cannot be continuously used, and is not suitable for large-scale production automation operation.

(5) The electromagnetic slag-stopping method is characterized by that an electromagnetic pump is mounted on the periphery of steel-tapping hole of converter, when the steel is tapped, the electromagnetic pump is started, and the produced magnetic field can be used for making steel flow become thin, so that the height of suction vortex produced on the molten steel surface above the steel-tapping hole can be reduced, and the slag can be effectively prevented from flowing out of the steel-tapping hole. However, the method has long tapping time, the tapping time of a large converter needs more than 15min, the labor production is greatly reduced, and the molten steel is seriously sucked.

(6) The sliding plate method for blocking slag is to install the refractory element of the sliding nozzle on the steel tapping hole of the converter and to open or close the steel tapping hole mechanically or hydraulically to reach the purpose of blocking slag. The device has good slag blocking effect, but the device has complex equipment and higher cost. In addition, the device is arranged at a specific position of the steel tapping hole, is influenced by splashing during converting, and is inconvenient to mount and dismount.

(7) The pneumatic slag-stopping method adopts a slag outflow detection device, which is composed of an element for sending and receiving signals and a signal processing device, and can detect the change of the flow of molten steel passing through a steel-tapping hole through the change of voltage generated by a secondary coil, thereby accurately controlling the slag-stopping time. When stopping slag, the slag stopping plug is used for mechanical sealing, and the end part of the plug sprays high-pressure gas to prevent slag from flowing out. This method has obvious advantages in terms of rapidity, reliability and cost. However, when steel slag is mixed out due to the suction vortex generated during steel tapping, the slag stopping time is not easy to master, the working condition is severe, and parts are frequently replaced.

(8) The method of using a slag-stopping bar, in which the slag-stopping bar is suspended on a boom so as to be freely movable in a converter, is to close a tap hole from the inside of the converter to stop slag immediately before tapping. The device is less adopted because of the complexity of operation and maintenance.

In conclusion, it can be seen that the main converter slag stopping technology at present: the simple and economic slag stopping technology has low efficiency, the technology with high slag stopping efficiency has complex device, high use cost and obvious advantages and disadvantages, and various converter slag stopping methods are mostly intervention in the later period of tapping and have poor control on the slag amount in the early period and the middle period. The prior art published at present lacks 'economic and efficient process technology for reducing the slag discharge amount of the converter'.

The slag blocking technology focuses on optimizing and improving slag blocking equipment to reduce the slag discharge amount in the converter tapping process, and no research is carried out on the technical effect of reducing the slag discharge amount of the converter by optimizing the inner cavity structure of the converter.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the convex cavity type converter overcomes the defects of the prior art, can reduce the slag discharge in the tapping process, can inhibit the generation of vortex, and reduces the slag discharge.

The convex-cavity converter capable of reducing the slag discharge amount in the tapping process comprises a converter, wherein a tapping hole is formed in the upper part of the converter, and the tapping hole protrudes outwards from the inner cavity of the converter to form an elliptic-cone-shaped convex cavity.

Through the optimal design of the shape of the inner cavity of the converter, the converter adopts the design of the outward protrusion of the steel tapping hole, the outward protrusion cavity is formed at the position of the steel tapping hole, the steel tapping hole of the converter is connected with the inner cavity of the converter through the outward protrusion cavity, compared with the traditional converter, the most prominent characteristics of the convex cavity type converter which can reduce the slag discharge in the steel tapping process are as follows: the inner cavity of the converter lining at the position of the steel tapping hole is protruded outwards, the capacity of the converter at the position of the steel tapping hole of the converter is increased, the depth of a molten pool at the position of the steel tapping hole is increased, the depth of a molten steel liquid level at the position of the steel tapping hole can be increased in the steel tapping process, the generation of eddy current can be effectively delayed by increasing the depth of the molten pool at the position of the steel tapping hole, and therefore the slag falling of the converter caused by eddy current slag rolling is reduced.

Further preferably, the convex cavity body is formed by extending outwards along the axis of the steel tapping hole. The convex cavity body is formed by extending outwards along the axis of the steel tapping hole pipeline at the position of the steel tapping hole of the original traditional converter;

further preferably, the convex cavity intersects with the side wall of the inner cavity of the converter to form a bottom surface a of the convex cavity, the bottom surface a is a curved surface, and the maximum area s of the projection of the bottom surface a is provided; the vertex D of the convex cavity is connected with the inner hole of the steel tapping hole pipeline, and the distance between the vertex D and the maximum projection area s is the depth h of the convex cavity. Namely, the distance between the vertex D and the plane where the maximum projection area s is located is the depth h of the convex cavity.

Further preferably, the nominal capacity of the converter is 100t-300t, and the depth h of the convex cavity is 0.4m-0.8 m.

Further preferably, the nominal capacity of the converter is 100t-300t, and the volume v of the convex cavity is 1.5-3.0m³。

Further preferably, the diameter of the steel-tapping hole is enlarged by 10% -20%. The convex cavity design meets the critical bath height for eddy current suppression. Considering the effective effect of the convex cavity on vortex suppression, the steel tapping injection speed is properly increased, compared with the traditional converter, the diameter of the steel tapping hole is increased by 10-20% on the basis of the traditional steel tapping hole, so that the steel tapping time is reduced to 1/1 (1.1-1.2)²× 100 percent (69-82 percent), can reduce the suction of molten steel in the tapping process, and is beneficial to smelting clean steel.

The invention relates to a convex cavity type converter tapping process capable of reducing the slag discharge amount in the tapping process, which comprises the following steps:

(1) before smelting, a slag blocking cap is arranged from a steel tapping hole;

(2) tapping: the steel tapping hole protrudes outwards towards the inner cavity of the converter to form an elliptic conical convex cavity, and the convex cavity extends outwards along the axis of the steel tapping hole;

1) starting a rocking furnace: the instant slag and the molten steel flow from the convex cavity body to the steel outlet direction, and the slag blocking cap effectively blocks the instant slag to avoid initial slag discharging;

2) and (3) beginning tapping: the inclination angle of the converter is 75-85 degrees, and molten steel passes through the convex cavity and is discharged to a steel outlet;

3) in the middle stage of tapping: the converter inclination angle is 85-95 degrees, full flow is kept in the convex cavity, the depth of a molten pool is at least the depth h of the convex cavity, vortex production is effectively inhibited, and the slag discharge caused by vortex slag entrapment is reduced;

4) and (3) in the later tapping stage: the inclination angle of the converter is 95-105 degrees, a slag stopping ball or a slag stopping cone is thrown into the converter, molten steel is reduced, the liquid level of the molten steel gradually drops into the convex cavity, the convex cavity guides the slag stopping ball or the slag stopping cone, the slag stopping ball or the slag stopping cone is pushed to accurately move towards the steel tapping hole, and the slag discharging amount in the later steel tapping period is reduced. After the liquid level of the convex cavity molten pool is reduced, the convex cavity has a position limiting effect, so that the slag blocking ball or the slag blocking cone is prevented from drifting, the slag blocking ball or the slag blocking cone accurately flows to the upper part of a steel tapping hole of the converter through the convex cavity, the slag blocking ball or the slag blocking cone has a slag blocking effect, the slag blocking efficiency at the last stage of steel tapping is greatly improved, and the slag discharging amount at the last stage of steel tapping is reduced.

Further preferably, the convex cavity intersects with the side wall of the inner cavity of the converter to form a bottom surface a of the convex cavity, the bottom surface a is a curved surface, and the maximum area s of the projection of the bottom surface a is provided; the vertex D of the convex cavity is connected with the inner hole of the steel tapping hole pipeline, and the distance between the vertex D and the bottom surface a is the depth h of the convex cavity. Namely, the distance between the vertex D and the plane where the maximum projection area s is located is the depth h of the convex cavity.

Further preferably, the nominal capacity of the converter is 100t-300t, and the depth h of the convex cavity is 0.4m-0.8 m.

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

1. the novel converter is provided with the convex cavity protruding outwards and the novel converter with the convex cavity structure, the convex cavity is communicated with the steel tapping hole and the converter body, a molten pool with higher liquid level is formed above the steel tapping hole, and under the condition that the pouring speed of the steel tapping flow is not changed, the generation of vortex can be inhibited, and the slag discharge amount is reduced.

2. The depth of a molten pool of the convex-cavity converter capable of reducing the slag discharge amount in the tapping process is far greater than the critical vortex generating depth, the diameter of a tap hole can be properly increased by 10-20%, the vortex slag entrapment cannot be influenced, the tapping time can be reduced to 69-82% of the original tapping time, the suction gas in the molten steel tapping process is reduced, and the convex-cavity converter is very beneficial to smelting clean steel;

3. the convex cavity type converter capable of reducing the slag discharge in the tapping process can reduce the slag discharge by 70 percent through conservative estimation, about 5.6kg/t of steel and the consumption of aluminum deoxidizers in the refining process, and the annual economic benefit conservative estimation of one converter with the nominal capacity of 300 tons is 1400 ten thousand yuan;

4. because the design and the manufacture of the convex cavity type converter have smaller difficulty, the converter can be easily improved on the basis of the traditional converter type, and the creative design does not introduce complicated mechanical equipment and refractory material devices, has the characteristics of excellent slag blocking effect, convenient use, excellent economy and the like, and has good application prospect.

5. According to the process, when the converter initially taps, the molten steel is matched with the slag stopping cap for use, the convex cavity is rapidly filled with the molten steel, the converter slag floats upwards to the upper part of the convex cavity, the initial tapping of the converter can be effectively avoided, and the molten steel depth of the convex cavity can effectively avoid the generation of eddy current; in the middle tapping stage of the converter, the convex cavity part is effectively communicated with a molten pool in the furnace body, the upper part of a tapping hole is always kept to have higher molten steel depth, the generation of vortex is effectively inhibited, and the slag falling amount of vortex slag entrapment is greatly reduced; in the later tapping stage of the converter, after the liquid level of the convex cavity molten pool is reduced, the convex cavity body has a position limiting effect, and can guide the slag blocking ball and the slag blocking cone to prevent the slag blocking ball and the slag blocking cone from drifting, so that the slag blocking ball and the slag blocking cone have an accurate slag blocking effect, the slag blocking efficiency in the last stage of tapping is greatly improved, and the slag discharging amount in the last stage of tapping is reduced.

Drawings

Figure 1 is a schematic cross-sectional view of an embodiment of the present invention,

FIG. 2 is a schematic sectional view A-A of FIG. 1,

figure 3 is an enlarged schematic view of the structure at B in figure 2,

FIG. 4 is a schematic view of the convex cavity and the tap-hole profile,

FIG. 5 is a schematic view of an initial state of smelting according to an embodiment of the present invention,

FIG. 6 is a schematic view showing the tapping state of the converter cradle,

FIG. 7 is a schematic view showing the initial tapping state of the converter cradle,

FIG. 8 is a schematic view showing the tapping state at the later stage of the rocking of the converter,

FIG. 9 is a schematic view of an initial state of a conventional converter in the prior art,

FIG. 10 is a schematic view showing a state of tapping from a conventional converter cradle according to the prior art,

FIG. 11 is a view showing one of the initial tapping states of a conventional converter cradle of the prior art,

FIG. 12 is a schematic view showing a state of tapping at a later stage of a conventional converter cradle in the prior art,

figure 13 is a schematic view of an endoscopic topography of an embodiment of the present invention,

FIG. 14 is a schematic view of an endoscopic form of a conventional converter

Figure 15 is a plot of Froude norm versus vortex generation time,

FIG. 16 is a statistical chart showing the proportion of converter slag tapping at each stage of conventional converter tapping.

In the figure: 1. the steel tapping method comprises the following steps of (1) converter 2, molten steel 3, slag 4, a convex cavity body 5, a steel tapping hole 6 and a traditional converter;

in the figure, a is a curved surface of the intersection of the convex cavity of the converter and the inner wall of the converter;

in the figure, S is the projection area of a curved surface a;

in the figure, D is the top point of the convex cavity of the converter;

in the figure, L is an inclination angle in the converter tapping process;

where h is the depth of the convex cavity.

In fig. 7, L is 80 °;

in fig. 8, L is 100 °;

in fig. 11, L is 70 °;

in fig. 12, L is 115 °.

Detailed Description

The technical solution in the embodiments of the present invention will be further clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention:

as shown in figures 1-4, the convex-cavity converter capable of reducing the slag discharge amount in the tapping process comprises a converter 1, the nominal capacity of the converter is 100t-300t, a tapping hole 5 is formed in the upper portion of the converter 1, and the tapping hole 5 protrudes from the inner cavity of the converter 1 to form an elliptic-cone-shaped convex cavity 4.

The convex cavity 4 is formed by extending outwards along the axis of the steel tapping hole 5.

The convex cavity 4 is intersected with the side wall of the inner cavity of the converter 1 to form a convex cavity bottom surface a, the bottom surface a is a curved surface, and the projection of the bottom surface a is the maximum area s; the vertex D of the convex cavity 4 is connected with the inner pipeline opening of the steel tapping hole 5, and the distance between the vertex D and the maximum projection area s is the depth h of the convex cavity. Namely, the distance between the vertex D and the plane where the maximum projection area s is located is the depth h of the convex cavity.

The converter 1 and the steel tapping hole 5 can be built by heat-resistant bricks.

Mechanism analysis and explanation:

theoretical calculation

The slag in the middle and later tapping periods of the converter is mostly caused by vortex, and along with the reduction of the liquid level, the vortex is developed into air suction vortex from surface vortex. The time of generation of the air entrainment vortex depends on the initial conditions of the bath and the tapping speed, and the critical bath depth for forming the vortex increases with the increase of the initial circulation of the steel flow in the converter. The vortex generation critical bath depth increases as the molten steel injection rate increases.

(1) Time of eddy current generation

As shown in fig. 15, there are variables such as the bath level, tap hole diameter, nature of the slag, amount of slag, etc. that affect the eddy current characteristics. In this study, the slag parameters were defined as constants and analyzed by introducing Froude criteria, see Kingqiang, Lijun, Hanshijie, A numerical simulation study of eddy current slag entrapment during tapping in a converter, vanadium-titanium iron, 2012,33(3): 34-39.

In the formula, Q-steel tapping injection speed is cm 3/s; g-acceleration of gravity, cm/s 2; l-bath height, cm. Research shows that the Froude standard number is less than 0.03, the vortex generation time is 80% of the converter emptying time, and the Froude standard number is more than 0.03, so that the vortex generation time is greatly advanced, as shown in figure 1. From the analysis of the formula 1, because Froude standard number and two variables of the steel tapping injection speed and the depth of the molten pool are in relation, under the premise that the parameters of the steel tapping hole are not changed, namely the injection speed is not changed, the increase of the depth of the molten pool is an effective means for delaying the vortex generation time.

(2) Characteristics of eddy currents

The characteristics of the eddy currents can be explained by the principle of conservation of angular momentum and the bernoulli equation, see C H keum. development of a new slag-stopping method for converter tapping. wu steel technology, 1998,36(4): 19-23; see Wangjian, Lijun, Hanshijie, numerical simulation and water model study of converter tapping and vortex formation Special steels, 2012,33(2): 18-21.

The conservation of angular momentum in the flow field can be expressed by the following formula, coordinates are established by the center of an outlet, any position in a molten pool is selected as a bulk particle,

in the formula, L-angular momentum, mass of m-bulk particles, Yx-distance from the center of the outlet, Wx-angular velocity. From the equation 2, it can be seen that the angular velocity decreases with the distance from the center of the outlet, that is, the angular momentum at the position away from the steel-tapping hole becomes smaller, that is, the vortex characteristics are not obvious, that is, the generation of the vortex can be effectively inhibited by increasing the depth of the molten pool. The bernoulli equation is as follows,

in the formula, P₀-atmospheric pressure, Pa; d_s，d_l-the density of slag and steel, kg/m3, respectively; h_s，H_l-depth of slag and steel, m, respectively; g-gravitational acceleration kg m/s²V-tapping flow speed, m/s.

The position of the steel-tapping hole is lower because the speed of the steel-tapping flow at the center of the steel-tapping hole is maximum, so that a funnel-shaped vortex is formed. At the same time, another important factor affecting the vortex characteristics is the nature of the slag. The critical height for vortex formation increases as the steel to slag density ratio increases. The increase of slag viscosity or the reduction of steel viscosity can reduce the critical height of the eddy current of the molten pool, and as analyzed above, the increase of slag density and viscosity can inhibit the eddy current from carrying slag, which is the principle of slag modification to inhibit the eddy current from rolling up slag. As can be seen from equation 3, in order to maintain the bernoulli constant conservation, if the heights of the slag and the molten steel are increased, the flow rate of the molten steel can be appropriately increased without generating eddy currents under the condition that the densities of the slag and the molten steel are not changed.

Convex and concave cavity design

Theoretical calculation shows that the generation of vortex can be effectively delayed by increasing the depth of a molten pool at the position of the steel tapping hole, so that the slag falling of the converter caused by the slag rolling of the vortex is reduced. In order to increase the depth of a molten pool at the position of the steel tapping hole 5, the novel converter 1 adopts a steel tapping hole convex design.

An outer convex cavity 4 is formed at the position of the steel tapping hole, the converter steel tapping hole 5 is connected with the inner cavity of the converter 1 through the outer convex cavity 4, the outer convex cavity 4 is in an elliptic cone shape,

the convex cavity body is formed by extending outwards along the axis of the steel tapping hole pipeline at the position of the steel tapping hole of the original traditional converter;

the vertex D of the convex cavity is connected with the inner hole of the steel tapping hole pipeline;

the convex cavity is intersected with the side wall of the inner cavity of the converter to form a bottom surface a of the convex cavity, and the projection of the curved surface a has the maximum area s; the distance between the vertex D and the maximum projection area s is the depth h of the convex cavity, namely the distance between the vertex D and the plane where the maximum projection area s is located is the depth h of the convex cavity.

The volume of the mainstream converter of the existing equipment is 100t-300t, for example, the volume of the convex cavity can be designed to be 1.5-3 m³The depth h of the convex cavity can be 0.4-0.8 m, and the projection area s of the bottom surface a of the convex cavity can be 4-12 m²。

The convex cavity design meets the critical bath height for eddy current suppression. Considering the effective action of the convex cavity body on restraining the vortex, the pouring speed of the steel can be properly increased; compared with the traditional converter 6, the diameter of the steel tapping hole can be increased by 10-20%, so that the steel tapping time is reduced to 1 ÷ (1.1-1.2) 2 × 100 ÷ 69-82%), molten steel suction in the steel tapping process can be reduced, and clean steel smelting is facilitated.

As shown in fig. 5-8, the tapping process of the convex cavity type converter capable of reducing the slag discharge amount in the tapping process comprises the following steps:

(1) before smelting, a slag stopping cap is arranged from the steel tapping hole 5; as shown in fig. 5.

(2) Tapping:

1) starting a rocking furnace: after the converter is smelted, the converter is shaken to discharge steel, and in the beginning stage of the converter shaking, instant slag and molten steel 2 flow from the convex cavity body 4 to the steel outlet 5, the slag blocking cap effectively blocks the instant slag, then the convex cavity is quickly filled with the molten steel, and the slag floats upwards, so that the slag discharging in the initial stage of steel discharging is avoided.

2) And (3) beginning tapping: according to different furnace types, the inclination angle of the converter 1 is 75-85 degrees, the converter rocking speed is reduced, tapping is started, and molten steel 2 passes through the convex cavity body 4 and is tapped to a tapping hole 5; the molten steel depth of the convex cavity 4 can effectively avoid the generation of vortex; as shown in figure 7 of the drawings,

3) in the middle stage of tapping: the inclination angle of the converter 1 is 85-95 degrees, the convex cavity 4 of the converter can be effectively communicated with a molten pool in the furnace body, the depth of the molten pool can be kept to be more than or equal to the depth h of the convex cavity 4, the eddy current production is effectively inhibited, and the slag discharge caused by eddy current slag entrapment is reduced; the upper part of the steel tapping hole 6 is always kept to have higher molten steel depth, so that the generation of eddy current is effectively inhibited, and the slag falling amount of eddy current rolling slag is greatly reduced;

4) and (3) in the later tapping stage: the inclination angle of the converter 1 is 95-105 degrees, a slag stopping ball or a slag stopping cone is thrown into the converter 1, the molten steel 2 is reduced, the liquid level of the molten steel 2 gradually drops into the convex cavity 4, the convex cavity 4 guides the slag stopping ball or the slag stopping cone, the slag stopping ball or the slag stopping cone is pushed to accurately move towards the steel tapping hole 5, and the slag discharging amount in the later tapping period is reduced. After the liquid level of the molten pool of the convex cavity 4 is reduced, the convex cavity 4 has a position limiting effect, so that the slag blocking ball or the slag blocking cone is prevented from drifting, the slag blocking ball or the slag blocking cone accurately flows to the upper part of a converter steel tapping hole 5 through the convex cavity 4, the slag blocking ball or the slag blocking cone has a slag blocking effect, the slag blocking efficiency at the last stage of steel tapping is greatly improved, and the slag discharging amount at the last stage of steel tapping is reduced; as shown in fig. 8. The slag blocking ball and the slag blocking cone can be used according to the conventional operation method in the prior art, and are not described in detail.

FIGS. 9 to 12 are schematic views of the tapping process of the conventional converter, and FIG. 5 is a comparison with FIG. 9; FIG. 6 compares to FIG. 10; FIG. 7 compares to FIG. 11; FIG. 8 compares to FIG. 12; by comparing the tapping process of the convex-cavity converter capable of reducing the slag discharge amount in the tapping process with the steel processing process of the traditional converter 6, the invention can find that the depth of a molten pool at the tapping hole position of the convex-cavity converter capable of reducing the slag discharge amount in the tapping process is greatly increased, the generation of vortex can be effectively delayed, the generation of vortex slag entrapment probability is reduced, and the slag discharge amount of the converter is reduced.

As shown in fig. 9, a tap hole structure of a conventional converter is shown; as shown in fig. 1-5, the configuration of the convex cavity at the tap-hole location in the present invention is shown, and the convex cavity increases the depth of the molten bath at the tap-hole location during tapping.

FIG. 13 is a schematic view showing the endoscopic appearance of the convex cavity from the opening of the converter; FIG. 14 shows a schematic view of the endoscopic topography of the tap hole from the opening of a conventional converter; the convex cavity body is arranged at the position of the steel tapping hole, and can increase the depth of a molten pool at the position of the steel tapping hole in the steel tapping process and inhibit the eddy slag entrapment phenomenon.

FIG. 16 is a statistical chart of the proportion of converter slag tapping at each stage of converter tapping, which is made by a large amount of statistical data by each iron and steel enterprise, wherein the slag tapping proportion at the early stage, the middle stage and the final stage of converter tapping are respectively as follows: 30%, 30% and 40%. Compared with the convex cavity type converter capable of reducing the slag discharge in the tapping process and the traditional converter tapping process, the convex cavity type converter capable of reducing the slag discharge in the tapping process can completely avoid eddy slag entrapment in the early and middle stages of the converter tapping, can effectively reduce the slag discharge in the final stage of the converter tapping, and can reduce the slag discharge by 70% in the overall conservative estimation.

The slag amount of the converter is generally considered to be 8-13kg/t steel, and the lower limit is calculated to reduce the slag amount by about 5.6kg/t steel. The ladle top slag contains 10-17% of FeO, and the average content of FeO is 13%, so that a large amount of deoxidizer is consumed during molten steel refining. Taking the aluminum deoxidizer as an example, the aluminum deoxidizer consumed per 100kg of top slag was 100 × 13% × (2 × 27)/(3 × 62 × 0.5) ≈ 7.6(kg) when the aluminum utilization rate was calculated by the reaction equation of 3FeO +2a1 ═ 3Fe + Al2O3 and the aluminum utilization rate was 50%.

The cost of the aluminum deoxidizer is saved by one 300t converter year by about: 5.6kg slag/t steel x 300t steel/furnace x 30 furnace/day x 350 operation day/year x 7.6kg aluminium/100 kg slag x 11 yuan/kg aluminium ≈ 1475 ten thousand yuan. Therefore, the convex cavity type converter capable of reducing the slag discharge amount in the tapping process does not consider the product quality loss caused by the over standard of silicon and phosphorus elements due to slag discharge, and can obtain the annual economic benefit of 1400 ten thousand yuan only by reducing the slag discharge.