JP2004003713A - Molten slag cooling method and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molten slag cooling method and its apparatus which prevents pulverization of a slag by maximizing quench effect of the slag and by minimizing variation of the quench effect due to variation of slag pouring speed in equipment for mechanically shearing, granulating and distributing the molten slag and cooling it in a rotating scavenging hood. <P>SOLUTION: In a method for mechanically shearing and granulating molten slag by pouring it over a rotating drum having a plurality of blades arranged and rotating at a high speed, a spray cooling water amount (ton / minute) in a rotating scavenging hood is controlled in the range of 0.5 to 2.5 times of a slag pouring speed (ton / minute). Also, in the above cooling method, a collision board shielding 10 to 90% of the cross sectional area of the rotating scavenging hood is installed at 0.1 to 0.5 L location in the rotating scavenging hood from the rear end board. L is the length of the rotating scavenging hood. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention minimizes fluctuations in the quenching effect due to fluctuations in the pouring speed in a facility for mechanically shearing and dispersing molten slag and cooling it in the rotary collection hood while maximizing the slag quenching effect. The present invention relates to a method and an apparatus for cooling molten slag that prevents slag from being pulverized.
[0002]
[Prior art]
Conventionally, CaO or CaCO ₃ used in large quantities in the in-furnace refining process does not slag sufficiently in the slag discharged from steel smelting furnaces such as converters and electric furnaces, and so-called undecomposed lime is 0. About 1 to 4% remains. In order to protect the refractory from the steel smelting furnace refractory, the MgO component of the lining refractory that is eluted in the slag by the thermal spalling phenomenon and mixed in the slag, and further to protect the refractory in the furnace, The MgO content derived from the charged brick scraps is also included, and about 0.1 to 2% of undehydrated MgO remains in these MgO content.
[0003]
When these undehydrated CaO and undehydrated MgO remain in the slag and are used for roadbed materials, fine aggregates, temporary materials, etc., moisture and CaO + H ₂ O in the environment of use over a long period of time → A hydration reaction of Ca (OH) ₂ , MgO + H ₂ O → Mg (OH) ₂ occurs, and a volume expansion of about 2 times occurs. This volume expansion causes local swell on the road where the slag is constructed, or when cracking is lost when used in a molded product such as a tetrapot, before shipping to the civil engineering materials, etc. A so-called steam aging treatment is carried out in which the hydration reaction is accelerated in an atmosphere of 80 to 100 ° C., in which steam is normally blown into the steelmaking slag for 3 to 4 days under atmospheric pressure, and the residual expansion allowance is almost eliminated. Has been implemented.
[0004]
Although this treatment method can achieve a low residual expansion rate of 0.5% or less, it requires a large amount of steam because it uses a large amount of steam. There were difficulties such as requiring a steam aging treatment plant. In addition to transporting and transporting steelmaking slag to the steam aging treatment plant, transportation costs and vehicle costs for heavy equipment for loading are also required, and there are also problems that deteriorate the working environment such as dust generation during slag handling.
[0005]
On the other hand, slag discharged from steel smelting furnaces such as converters, electric furnaces, etc., once received in a molten slag container, then transported to a slag treatment plant, tilted through the slag container and allowed to solidify by natural cooling. After that, it was crushed and subjected to the steam aging treatment before being shipped. This solidification method requires a small amount of capital investment and is cooled and solidified by natural cooling, so that it has advantages such as low utility costs and is widely adopted. On the other hand, because it requires a large area between soils and generates heat and generates dust, there is a problem not only in the work environment but also in the surrounding environment, especially in factories close to residential or commercial areas. Is a serious problem.
[0006]
However, a method of tilting the molten slag container and applying the slag flow flowing down to the impeller rotating at high speed, shearing and granulating with the impeller, and spraying water into the slag collecting container to rapidly cool and solidify has become widespread. Yes. In addition, a method of spraying high-pressure water from the back of the flowing slag flow and granulating with high-pressure water energy and rapidly solidifying has been studied. Each method is based on wet processing using cooling water, and has the advantage of having a compact footprint and greatly improving the surrounding environment in addition to the work environment with high heat and dust generation. .
[0007]
Among them, for example, a method of granulating and dispersing molten slag disclosed in Japanese Patent Publication No. 7-96458 and Japanese Patent Publication No. 7-96459 and cooling it with water mist and ventilation in a rotary collection hood is disclosed. However, the granulated slag scattered from the rotating drum collides with the rotating collection hood, and then falls to the lower part of the rotating collection hood and is cooled by the remaining cooling water that flows down. It is divided roughly into what jumps into the discharge hole. Since the former is cooled without interruption, it is rapidly cooled to about 300 to 400 ° C., whereas the latter is discharged at a high temperature of about 800 to 1000 ° C. because the cooling time is short. The latter slag, which does not participate in the quenching effect, subsequently exhibits a remarkable pulverization phenomenon, resulting in variations in the quality of the treated slag.
[0008]
[Problems to be solved by the invention]
However, the pouring speed from the molten slag container is greatly affected by the viscosity of the deformed slag in the state of the surface skinning, the tilting speed fluctuation of the container, and the like. When over-injection occurs, problems such as welded coalescence of granulated slags and adhesion to the inner wall of the rotary collection hood, as well as a significant decrease in the cooling rate of the granulated slag, result from the transformation of 2CaO · SiO ₂ There was a problem of inducing the slag powdering phenomenon. In addition, since the pouring operation needs to be tilted while carefully monitoring the flow of pouring flow from the molten slag container in order to suppress fluctuations in pouring speed as much as possible, it is ejected from the rotary collection hood. It is necessary to quickly discharge the steam from the rear of the rotary collection hood out of the system with an exhaust blower so that water vapor does not flow out to the container side and interfere with the pouring flow monitoring. Incurred an increase in costs.
[0009]
[Means for Solving the Problems]
When molten slag containing dicalcium silicate (2CaO · SiO ₂ ) discharged from converters, electric furnaces, etc. is gradually cooled in the atmosphere, it transforms into γ phase and expands by about 10 to 15%. There was a difficulty of powdering. In order to solve the above-mentioned conventional problems, the inventors need a cooling rate of 30 ° C./second or more for molten slag, and as a result of a test using an infrared image furnace, about 600 ° C. In the following, a method and apparatus capable of suppressing powdering by transforming into a β phase having a very small volume expansion by preferably rapidly cooling to 400 ° C. has been found and led to the invention.
[0010]
The gist of the invention is that
(1) In a method of pouring molten slag onto a rotating drum that rotates at high speed by arranging a plurality of blades and mechanically granulating the slag, the amount of sprinkling cooling water (ton / min) is poured into the rotary collection hood. A method for cooling molten slag, wherein the molten slag is controlled within a range of 0.5 to 2.5 times the dredging speed (ton / min).
(2) In the method for cooling molten slag as described in (1) above, 10 to 90% of the sectional area of the rotary collection hood is shielded in the rotary collection hood at a position of 0.1 to 0.5 L from the rear end plate. A method for cooling molten slag, comprising installing a collision plate. However, L is the length of the rotary collection hood.
(3) The method for cooling molten slag according to (1) or (2), wherein the molten slag container is tilt-controlled by observing the pouring flow with an infrared monitoring device.
(4) A molten slag granulating apparatus comprising a rotating drum having a plurality of blades for shearing molten slag and a hood that covers the granulated slag blown from the rotating drum and sprays water while cooling. An apparatus for granulating molten slag, characterized in that an impingement plate for granulated slag that shields 10 to 90% of the cross-sectional area of the hood is provided inside the hood.
[0012]
(5) The melting slag granulating apparatus according to (4), wherein the melting slag is installed at a position of 0.1 to 0.5 L from the rear end of the hood with respect to the hood full length L. Slag granulating equipment.
(6) The molten slag granulation apparatus according to (4) or (5), wherein an infrared monitoring device is provided to detect the amount of molten slag poured into the rotating drum. Device.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing the relationship between the amount of sprinkling cooling water / pouring speed ratio (water / slag ratio) and the average temperature of the slag on the outlet side of the rotary collection hood. As shown in FIG. 1, 2.5 {(water spray cooling water amount (ton / min) / injection speed (ton / min)} or less under conditions without a collision plate, 0.5 to 1 even under collision plate installation conditions It is understood that the ratio of sprinkling cooling water / injection speed (hereinafter referred to as water / slag ratio) of 1. is required, and if the impact plate installation position exceeds 0.5 L, the granulated slag that collides with the impact plate Bounces back to the rotating drum and leaks out of the system from the side with the rotary collection hood, leading to a decrease in yield, and if it is less than 0.1 L, the granulated slag that falls on the collision plate immediately becomes the rotary collection hood discharge hole. Since it is discharged from the water, the contact time with the remaining hot water is shortened and the cooling effect cannot be enjoyed.
[0014]
From the above, the cooling water supply pump that detects the change in the weight of the casserole with the load cell and sprays it into the rotary collection hood with a signal multiplied by the water / poison ratio defined by the time change (ton / min) Control the output. Alternatively, the change in the total weight of the storage tank is detected by the load cell, and the amount of cooling water supplied is subtracted by a factor of 1 or less (considering the amount of evaporation of cooling water) and the amount of change over time (ton / This can be achieved by controlling the output of the cooling water supply pump with a required flow rate signal multiplied by the water / soot ratio defined in (min).
[0015]
In addition, if the collision area of the collision plate exceeds 90%, the gap between the rotary collection hood wall and the collision plate plate is narrow, resulting in hindrance to slag movement in the rotary collection hood, and conversely less than 10%. If so, a sufficient cooling effect cannot be expected because the ratio of the scattered slag colliding and dropping to the front of the discharge hole is reduced. Therefore, it was set to 10 to 90%. That is, a collision plate that shields 10 to 90% of the sectional area of the rotary collection hood is installed from the rear end plate of the rotary collection hood at a position of 0.1 L to 0.5 L of the length L of the rotary collection hood. By doing so, it is possible to eliminate any slag that jumps directly from the rotary drum into the rotary collection hood discharge hole, so that the entire slag is rapidly cooled to prevent pulverization and to suppress quality fluctuations.
[0016]
In addition, since a large amount of water vapor is generated from the rotary collection hood during operation of the granulation facility, it is discharged out of the system with an exhaust blower that has a steam discharge port that penetrates the rear end panel. Steam also leaks from the front of the collection hood, obstructing the view of the worker who tilts the ladle while watching the pouring flow, so the pouring speed fluctuates greatly or the pouring operation itself must be interrupted Cases occurred frequently. For this reason, a high-sensitivity infrared camera is installed as a pouring flow monitoring device at the position where pouring flow is desired, so that the pouring flow can be clearly observed even in water vapor, and the container tilting speed can be controlled by the operator. This has the advantage of stabilizing the injection speed and not requiring a forced exhaust system for steam such as an exhaust blower.
[0017]
In addition, an infrared image sensor is used as a pouring flow monitoring device to adjust the pouring amount of the molten slag into the rotating drum by observing the heat distribution during pouring of the slag to optimize granulation and to respond to the pouring amount. It is possible to adjust the cooling water, stabilize the granulation, improve the productivity by optimizing the cooling, and reduce the processing cost by reducing the amount of cooling water, and automate the granulating device. Eliminates high heat work and improves the stability of the device.
[0018]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
As described above, FIG. 1 shows the relationship between the water / soot ratio and the rotational hood outlet side slag average temperature (hereinafter referred to as T). As shown in this figure, T decreases as the water / soot ratio increases, but the effect of drastically improving the cooling effect of the granulated slag is greatly improved by installing a collision plate. Furthermore, the effect becomes remarkable from the collision plate installation position from the 0.1L position, and the effect is further increased at the 0.5L position, but when it exceeds the 0.5L position, the granulated slag into the rotary collection hood entry side Since popping out becomes remarkable, the range was made into 0.1-0.5L.
[0019]
FIG. 2 is a schematic view of a conventional cooling device for molten slag without a collision plate. As shown in this figure, the molten slag 2 discharged from the steelmaking furnace is received by the discharge pan 1, and the discharge pan 1 is tilted on the injection chute 4 to the mechanical shear granulation wet quenching apparatus. To start. The pouring flow 3 passes the pouring chute 4 and guides the molten slag 2 onto the rotating drum 6 and flows down onto the rotating drum 6 rotating at high speed. The molten slag 2 flowing down is sheared and granulated by blades 5 attached to the surface of the rotary drum 6 and scattered in a rotating rotary collection hood 13 and rapidly cooled by radiation cooling and sprinkling 11 cooling.
[0020]
However, the slag of the granulated slag direct discharge track 8 without colliding with the rotary collection hood 13 is cooled by the hot water mixed flow 14 after the granulated slag collision track 9 colliding with the rotary collection hood 13. It is discharged at a higher temperature than slag. This caused a decrease in cooling efficiency and temperature variation of the discharge slag 15. Further, in the operation of such a granulating facility, a large amount of water vapor is generated from the rotary collection hood 13, so the steam discharge port 17 is installed in a form penetrating the rear end plate 29 of the rotary collection hood 13 and exhausted. It is discharged out of the system by the blower 30. Further, the discharged slag is conveyed in a state where a granulated slag layer 19 is formed on the conveyor 18. In addition, the code | symbol 10 is a cooling water sprinkling pipe, 16 shows the slag jump-in prevention board to a steam discharge port.
[0021]
FIG. 3 is a schematic view of a molten slag cooling device provided with a collision plate according to the present invention. As shown in FIG. 3, the scattered slag collides with the collision plate 20 to become a falling flow 21 and is rapidly cooled in the hot water mixed flow 14, so that the cooling effect is improved and the temperature variation of the discharge slag 15 is also reduced. 4 is a cross-sectional view taken along the line AA ′ in FIG. 3, and the collision plate 20 is attached to the rotary collection hood 13 by a fixing bracket 22, and the collision plate 20 has a sprinkle 11 for preventing seizure. Is supplied from the cooling water sprinkling pipe 10.
[0022]
FIG. 5 is a schematic view of a molten slag cooling device showing another embodiment provided with a pouring flow monitoring device 12 according to the present invention. As shown in this figure, the pouring speed W1 is determined from the output change of the pot pan weighing table 24, and from the output change of the storage tank weighing table 28 on which the granulated slag 27 and hot water 26 in the tank 25 are placed. Since the sum W3 of the granulated slag generation rate and the residual evaporation water supply rate W2 is known, the water spray rate = (W3−W1) / (K × W1), where K <1 is a coefficient, and the water spray amount is controlled. be able to. Reference numeral 23 denotes a trunnion.
[0023]
【The invention's effect】
As described above, by installing the collision plate according to the present invention, there is no slag jumping directly from the rotary drum into the rotary collection hood discharge hole, powdering of the entire slag is prevented, quality fluctuation is suppressed, and By applying a high-sensitivity infrared monitoring device, it is possible to clearly observe the pouring flow even in water vapor, so that the container tilting speed can be controlled by the operator. In addition, the amount of molten slag poured into the rotating drum can be adjusted by looking at the heat distribution during slag pouring with an infrared monitoring device to optimize granulation and adjust the cooling water according to the amount of pouring. , Stabilization of granulation, improvement of productivity by optimizing cooling, further reduction of processing costs by reducing the amount of cooling water, elimination of high temperature work by automation of granulation equipment, improvement of stability of equipment, etc. It is effective.
[Brief description of the drawings]
FIG. 1 is a diagram showing a relationship between a water / soot ratio and a slag average temperature on a rotary collection hood outlet side.
FIG. 2 is a schematic view of a conventional cooling device for molten slag without a collision plate.
FIG. 3 is a schematic view of a molten slag cooling device provided with a collision plate according to the present invention.
4 is a cross-sectional view taken along the line AA ′ in FIG. 3;
FIG. 5 is a schematic view of a molten slag cooling device showing another embodiment provided with an injection flow monitoring device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Waste pan 2 Molten slag 3 Injection flow 4 Injection chute 5 Blade 6 Rotating drum 7 Splash prevention plate 8 Granulated slag direct discharge track 9 Track after granulated slag collision 10 Cooling water sprinkling pipe 11 Sprinkling 12 Pouring flow monitoring Device 13 Rotary collection hood 14 Hot water mixed flow 15 Discharge slag 16 Slag jump-in prevention plate 17 Steam discharge port 18 Conveyor 19 Granulated slag layer 20 Collision plate 21 Falling flow 22 Fixing bracket 23 Trunnion 24 Pot pan weighing table 25 Storage Tank 26 Hot water 27 Granulated slag 28 Storage tank weighing table 29 Rear end plate 30 Exhaust blower

Claims (6)

In a method in which molten slag is poured onto a rotating drum that rotates at high speed by arranging a plurality of blades and mechanically sheared and granulated, the amount of sprinkling cooling water (ton / min) is poured into the rotary collection hood at the injection speed ( (ton / min) is controlled within a range of 0.5 to 2.5 times the molten slag cooling method. 2. The method for cooling molten slag according to claim 1, wherein 10 to 90% of the cross section of the rotary collection hood is shielded at a position of 0.1 to 0.5 L from the rear end plate in the rotary collection hood. A method for cooling molten slag, comprising installing a plate. Where L is the length of the rotary collection hood 3. A method for cooling molten slag according to claim 1, wherein the molten slag is controlled by tilting the molten slag container by observing the pouring flow with an infrared monitoring device. A molten slag granulating apparatus comprising: a rotating drum having a plurality of blades for shearing molten slag; and a hood that covers the granulated slag blown from the rotating drum and sprays water while cooling. An apparatus for granulating molten slag, characterized in that an impingement plate for granulated slag that shields 10 to 90% of the cross-sectional area of the hood is provided inside the hood. The molten slag granulation apparatus according to claim 4, wherein the molten slag granulation is installed at a position of 0.1 to 0.5 L from the rear end of the hood with respect to the full length L of the hood. apparatus. 6. The apparatus for granulating molten slag according to claim 4 or 5, further comprising an infrared monitoring device for detecting the amount of molten slag poured into the rotating drum.

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