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Skateboards method of converter slag tapping technology overview

Word:[Big][Middle][Small] 2015/11/14    Viewed:903    

Yang Yi Li-kun wang Yang Yufu

Maanshan Yushan New Metallic Materials Co., Ltd. (Anhui Maanshan, 243000)

Abstract: with the rapid development of steel industry, user requirement for the quality of steel is increasing day by day, and the slag can be many effects on the converter steelmaking production and subsequent processes, converter slag skateboard method can effectively control of converter slag under the early and late, improve cleanliness of molten steel. The purpose of this paper is to skateboard from converter slag technology background, process principle and practical use, the next topic of converter slag produced in the process of converter steelmaking skateboard method the advantages and the visible economic benefits and development prospects.

Key words: converter; Steel; The slag; The skateboard slag

1 technical background

With the rapid development of steel industry, the user requirement for the quality of steel is increasing day by day. Therefore, the production of high quality, high technology content, high value-added steel products become the inevitable choice of iron and steel enterprises.

And molten steel quality and in the process of the converter steel slag quantity is directly related to, has become a converter smelting special steel, excellent steel constraint. To reduce the converter steel slag quantity is in the process of iron and steel industry in the pursuit of the eternal theme. Control of the process of the converter steel slag technology is one of metallurgical engineering technical personnel life research topic.

2 the harm of the slag

Under slag can cause many to converter steelmaking production and subsequent processes. Cause of molten steel, for example, returning the phosphorus, sulfur, affect the billet quality. Increase of inclusions in steel; Increase the furnace after the consumption of iron alloy, Increase the amount of synthetic slag in the subsequent refining process; Increase processing time refining process; Affect the service life of the ladle refractory material. Environmental pollution under the furnace and equipment of safe production, and other various question.

3 the converter steel slag process analysis

Converter tapping process, the slag is less than the proportion of molten steel and floating on the surface of steel, therefore, when the converter steel slag under consists of three parts: the early stage of the slag, converter tilting to the averaged 38 ~ 50 ° of early slag, slag, the early stage of the residue after started out of steel, can be observed that the vortex effect of steel slag; Late late slag, the tapping to the end of the steel phase, the converter steel to the quantity of the slag ladle, the former period of slag amount roughly 30%, the vortex effect from down the surface of the molten steel slag quantity is about 30%, the late slag by about 40%. [1]

Four commonly used method of slag

In early slag slag cap, soft slag; Using block late slag slag, slag, slag ball dart, pneumatic slag, slag gas blowing, electromagnetic slag, skateboard, slag.

The comparison of five kinds of slag method

Figure 1 and table 1 lists the existing form of slag under the effect of slag amount of contrast and comparison

Table 1 effect of slag of different slag method 

Slag method

The success rate of slag%

Under the converter steel slag ladle 
The average slag thickness 



Conical skin slag mo + slag slag ball




Conical tin slag slag cap + pneumatic manner



Electromagnetic induction coil is easy damaged, 
Equipment failure rate is high

Conical tin slag cap + slag dart slag



Auxiliary sentenced to slag slag under infrared detection technology

Slide gate + infrared slag detection technology



Full automatic slag

By a skateboard can be seen in figure 1 slag and slag under the infrared detection combination can be stable and under the effective control of the average of per ton steel slag quantity, phase for other slag, has obvious advantages.

Six skateboards method of converter slag tapping process description

Skateboards method of converter slag tapping technology is maanshan rain metallurgy new materials co., LTD in the converter steel slag technology of domestic initiation. It USES two pieces of skateboards brick hole dislocation overlap fully open, half open and closed curtains to implement the converter separately slag tapping.

End of the converter smelting steel, when the converter tilting to 20 ~ 35 ° closed gate, all the previous slag in converter, converter tilting to 75 ~ 85 ° when steel slag have all through the tapping hole area increases after a open gate instructions out of steel, starting when the converter tilting until the end of 90 ~ 110 ° when tapping, infrared detector to detect the slag steel slag after issue closed gate instruction to the valve body, valve closed, as shown in figure 2. Due to the gate to close very fast, the closure of the tapping hole in time is less than 1 second (around 0.5 seconds), steel slag can be almost entirely of plugging in the furnace. Implementation of converter slag less slag tapping. It with the current used iron slag cap before slag, slag, slag dart slag after method than, slag, high success rate of 100%; Furnace slag effect is good, turn furnace under ladle slag layer thickness can be controlled in 40 mm or less. And slag can be through the infrared detection and PLC control technology, the combination of automatic found guilty of slag and slag, is currently the converter steel slag best a slag technology.

Skateboards method of converter slag tapping technology, mainly by the valve body under hardware and automatic slag detection system composed of two parts. Gate valve gate machinery hardware and points, assembly systems, rotary joints, hydraulic cylinder of the hydraulic pressure station and water cooling, air cooling system, the offline replacement maintenance system and consumption of refractory material: brick of tapping hole tube assembly, inner and outer nozzle brick and the internal and external skateboards brick.

Automatic slag under slag detection system refers to the infrared surveillance system, hydraulic electric control system and PLC control technology. Converter slag from steel technology with skateboard method replace the installation of the machine structure and use it without affecting the existing bof steelmaking process and operating conditions. For the offline overall replacement technology, namely in the debug frame to replace the offline agency new skateboards brick, after debugging qualified. Steps and measures as follows: first of all, the current converter tapping hole flange cover plate to be removed, install new design benchmark in the flange plate parts. Connection plate parts installed on the base plate, connection plate is equipped with four eyelet bolt and 2 root positioning pile, 2 dowel pin. Water-cooled cylinder components installed on the connecting plate and cylinder heat shield components, installation agencies; Modification and installation agencies shield; Install the new design of high pressure rotary joints and all pipe laying.

After use, unload the institutions from the debugging stage, placed in institutions treat with transportation storage rack, when online institutions skateboards brick life use to plan change, will shake converter tapping hole to furnace front position, and the institutional change at the edge of converter tapping hole, store shelves in transportation agency before shipped to the furnace, the skateboards brick joints evenly coated with chromium Corundum with forklift truck after fire clay replaced the institution to institution frame edge, electric hoist pushing mechanism by positioning the pile into the dowel with pneumatic tool will quickly four (or M36 eyelet bolt nut locking, and moving oil cylinder pushes the piston rod after the handle into the sliding box connecting channel oil cylinder pin connection, is installed. Easy to operate, simple, replacement time can be controlled within 10 ~ 15 minutes. Table 2 for the main parameters of existing institutions and can adapt to different sizes of converter now demand, table 3 for board slag tapping hole gate reached level.

Table 2 gate main parameters







Institutional dimension






Skateboards brick size

(length * width * thickness)






Skateboards brick pore size (D)






Sliding distance (L)






Spring number






Apply converter






Table 3 converter slag tapping hole board method gate level 





Apply converter




The success rate of slag




Change the time 




Skateboards brick life behind (curtains)




Closing time




The converter steel slag to ladle slag thickness on average




Institutional life expectancy




To protect institutions from the front spray slag stick to damage, furnace cap must be installed slide residue cover plate. The agency is under a protective covering from steel slag. So I need to the existing technical reform of converter:

Modified 1: tapping hole flange of the bof shell.

Transform 2: slag tapping hole slide confinement.

Reconstruction 3: rotary joint, oil, water and tracheal road paving.

Tapping hole by using the skateboard from converter slag need five pipe into the wall of converter trunnion tong to water-cooled oil cylinder and organizations, the five pipe are respectively in and out of the water cooled oil cylinder tubing 2 way; In and out of the water cooling pipe cavity 2 way; Institutions spring cooling tube 1 empty road.

Typically, existing in transforming a skateboard slag tapping process of converter, 2 high pressure oil tubing must be new, 2 water can cap from the furnace or oven to separate, don't have the luxury of, must transfer from rotary joint. So need to add a outside the original rotary joint at least 2 high pressure oil compressed air rotary joint, as shown in figure 3.

After several years of efforts, the slide block of converter slag tapping technology, has eight key core problem:

1, no slag tapping of converter technology; 2, long life of valve body; 3, long life of online oil cylinder; 4, long life of refractories; 5, institutions of rapidly changing technology; 6, tapping hole connection technology; 7, form a complete set of the laid of high pressure hydraulic source and water-cooled oil cylinder of converter connection technology.

Figure 3 slide block of converter slag system process arrangement

7 of converter steel slag detection principle diagram of the control system structure

Infrared under the principle of slag detection: converter slag under the infrared detection system based on the difference between steel slag and molten steel in a particular light wave band, shoot the steel images, use the camera and send images to industrial PC, after image acquisition card processing, by the software of collecting image signal processing, which can identify automatically distinguish steel flow of molten steel and steel slag, real-time identification and flow injection contains slag percentage. When testing to note down the slag, and surpassed in the system containing slag percentage, the system is combined with the slag flow injection form information such as the comprehensive analysis, output alarm signals in time, give skateboarding closing motion signal by a computer system at the same time, driven by hydraulic system to close stop tapping, thereby reducing slag into the bag, improve the purity of molten steel and steel yield, as shown in figure 4.

Eight of converter slag by slide method after the actual level of users

8.1 southwest of a steel plant of 210 t converter skateboard slag process is used to effectively control the ladle slag thickness

8.1.1 slag thickness measurement

Respectively for 1 # (skateboard slag), 2 # (slag dart) steelmaking converter after small platform for ladle slag thickness measurement, measure the furnace tapping process failed to join active lime, slag, such as the received continuous 100 each furnace slag thickness data.

Slag thickness contrast statistics of table 4


Thick samples/furnace slag

Slag thickness range/mm

The average slag thickness/mm

1#炉(The skateboard slag)




2#炉(Slag dart)




Figure 5 # 1, # 2 furnace slag thickness control of contrast

By table 4, figure 5 shows: 1 # furnace smelting steel ladle slag thickness control between 10 and 40 mm thick (slag control meet process by 40 mm or less), with an average of 28.24 mm, less putting-in-service proactively skateboard slag thickness of 2 # slag furnace by an average of 39.26 mm.

Skateboard slag after new technology is used, the converter slag under control have been improved significantly, slag thickness decreased significantly.

Figure 6 for different tonnage and tons of steel slag ladle slag thickness graphs.

Figure 6 different capacity under tons of steel ladle slag and slag thickness diagram

From figure 6 can estimate, when slag layer thickness in 40 mm, 300 t ladle under tons of steel slag quantity is about 5 kg; 250 t ladle is about 5.3 kg/ton; 210 t ladle is about 5.6 kg/ton; Is about 6 kg/ton to 180 t ladle; 150 t ladle is about 6.4 kg/ton; 120 t ladle is about 7 kg/ton; 100 t ladle of about 8 kg/ton; 70 t ladle is about 8.4 kg/ton. So if you need under tons of steel slag quantity < 5 kg, you need to block before + after blocking measures.

8.2 use effect

Phosphorus control 8.2.1 steel back

Tapping process of converter slag quantity under much direct effect on molten steel to P control. Represented by Q235B steel grade, compared to 1 #, 2 # furnace steel back to P.

Table 5 steel back to P


Steel grade


The finish of converterP/%

Casting productsP/%

Back to the amount of P /%

1# stove






2# stove






Note: 1 # furnace slag putting-in-service proactively skateboard, 2 # furnace slag dart slag.

Figure 7 steel rephosphorization contrast figure

Table 5, figure 7 shows: putting-in-service proactively skateboard steel slag furnace time back to the P content was 0.0020% on average, the use of slag dart molten steel slag furnace time back to P decreased by 0.0019%.

8.2.2 alloy elements yield

Q345B - T (thin) as the aluminum (aluminum and iron) DNA killed steel on behalf of the steel grade, the statistical analysis of the different ways of slag, slag dart slag and skateboard slag) Als, Si and Mn in the molten steel under the condition of three kinds of alloy elements.

Table 6 the alloy elements under different slag way yield












2.70- 41.05

70.97- 95.77

81.01- 97.47





7.41- 44.33

88.05- 97.56

85.79- 98.35

From table 6 shows:

(1) the steel slag furnace process using skateboard steel Als average yield of 29.69%, the use of steel slag dart furnace time water Als yield 10.27% higher on average.

(2) the tapping process using skateboard steel slag furnace time Si yield an average of 92.36%, compared with using steel slag dart furnace time Si yield 3.11% higher on average.

(3) the steel slag furnace process using skateboard steel Mn yield an average of 94.35%, compared with using steel slag dart furnace time Mn yield 1.27% higher on average.

Visible, the steel slag furnace process using the skateboard in molten steel alloy elements to some extent improve the recycling rate, including water deoxidation alloying steel using aluminum and iron Als yield increase sharply.

8.3 economical analysis

8.3.1 direct economic benefits

(1) spare parts consumption by Q1 to reduce the production cost

1 # converter using the skateboard slag after the late splash significantly reduce the amount of steel slag, steel slag, slag deposition of slag ladle car, car system significantly reduce the damage, the following table for 1 # converter using the skateboard slag equipment spare parts consumption before and after the contrast table.

Table 7 1 # converter using the skateboard slag equipment spare parts consumption before and after contrast

Before using

After using

total W1=150770 yuan/month

total W2=41520 yuan/month

Q1 = (W1, W2)/N = (150770-41520) / 150000 = 0.728 yuan/tons

W2 - use backup pieces of consumption, yuan/month;

W1 - before using the spare parts consumption, yuan/month;

N - 1 # furnace is mean monthly steel-producing quantity, 150000 t.

(2) alloy elements yield increase to reduce the cost of production

To calculate the process aluminum (aluminum and iron) DNA composed of converter steel slag tapping use skateboard after alloying elements yield increase Q2 (table 6) reduce the production cost.

Table 8 aluminum (aluminum and iron) DNA yield increase authors killed steel alloy elements

Q2 = Q21 + Q22 Q23 = 0.782 + 0.250 + 0.322 = 1.355 RMB/t * steel

(3) slag dart cost of per ton steel in Q3

Q3 = H/I = 218/210 = 1.038 yuan/t * steel

H - slag dart, price 218 yuan/set;

I - furnace product steel amount, 210 t/furnace.

(4) the skateboard Q slag direct economic benefits

Q = Q1, Q2 and Q3 - Q4 = 0.728 + 1.355 + 1.355-2.162 = 0.959 RMB/t * steel

Q4 skateboarding - 1 # converter steel slag cost 2.162 yuan/t *

Through the above results show: 1 # furnace skateboard slag direct economic benefit is 0.959 yuan/t * steel.

8.3.2 other benefits

Each slag dart 40 ~ 45 kg, the weight of the skateboard putting-in-service proactively slag system reduces the worker labor intensity, furnace slag under way is convenient for management, reduce the dangerous operations.

9 board method of converter slag tapping subject in the future

Skateboard of converter slag tapping the domestic existing technology about per shift change at a time, in order to improve the rhythm of steel; To reduce the cost of per ton steel consumption; Reduce the labor intensity of workers, the future development of optimization technology need from two aspects:

(1) in the existing refractory, long life due to inlay zircon plate composite board brick, but the production cost is higher, so now is not common for promotion. But with the mature production technology, the future will be to reduce the production cost, zirconium panels and further improve life inlay zircon plate composite skateboards brick, make price to rise, to the existing ordinary skateboards ~ life up to 12 ~ 18, from and decrease The Times of change to adapt to the needs of the fast rhythm of converter steelmaking.

(2) in order to further improve the efficiency of steelmaking, needs further research to promote double skateboard online replacement technology, so as to realize a skateboard furnace slag agencies use to 30, the ultimate goal to achieve more in once a day, so can greatly save change number, reduce the labor intensity of workers, to adapt to the fast pace of steelmaking technology.

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