JP3226822B2 - Method and apparatus for producing mold flux for continuous casting of steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a mold flux used for continuous casting of steel. The present invention relates to a technique for preventing the raw material slurry from adhering to a part of an injection surface and hindering uniform spraying of the raw material slurry.

[0002]

2. Description of the Related Art For example, mold flux added to a mold during continuous casting of steel plays various roles. In other words, to keep the surface of the molten steel to be cast warm, to prevent oxidation of the molten steel surface in the mold and to quickly dissolve the floating inclusions, to control the lubrication between the mold and the slab,
Tasks such as controlling the optimal heat removal from the slab are imposed.

[0003] These effects of mold flux (hereinafter simply referred to as "flux") have the effect of eliminating the surface defects of the slab and forming a beautiful casting surface, and in particular, the stability of the casting operation in the continuous casting operation. This is indispensable for securing and improving the yield of slab casting.

The flux is usually in the form of powder or granules (including hollow granules), and its components are generally CaO, S
It is made of iO ₂ as a main component, and in addition to Al ₂ O ₃ , a compound of an alkaline earth metal and an alkali metal (oxide, carbonate, fluoride, etc.). Further, a flux composition is formed by adding carbon in order to adjust the melting rate. In the case of a granular form, an organic or inorganic binder or the like is used to maintain a certain shape.

However, as a method for producing a hollow granular flux, a raw material flux containing the above composition is mixed with an appropriate amount of water to form an aqueous slurry, which is sprayed from a nozzle into a hot air drying tower (chamber). Then, it is dried by exposure to hot air to obtain a product flux having an appropriate particle size.

As a known technique of such a method for producing a flux, Japanese Patent Publication No. 3-79100 is disclosed. The gist of this technology is that an aqueous slurry containing a carbonaceous powder and a flux component for metal casting is made, and the aqueous slurry is spray-dried to evaporate water. Generated, and the carbonaceous powder is dispersed and contained throughout the solid portion in the particle, and the ratio of the carbonaceous powder on the surface of the particle in the solid portion is larger than the ratio of the carbonaceous powder in the entire particle. It is characterized by having.

Although the publication does not specifically mention a production apparatus, according to the above-described method for producing a flux for metal casting, spray drying involves dispersing an aqueous slurry as atomized particles from a sprayer by a supply pump. Then, the dispersion is put on the hot air supplied from the air heating and lowered in the drying chamber, and during the descent, the particles are heated with the hot air to instantaneously evaporate the moisture in the particles to form voids in the particles. In addition, it is described that the particles are dried to obtain spherical particles having a porous structure, and the particles thus obtained are introduced into a cyclone together with hot air, where the product and the hot air are separated to obtain a desired flux.

[0008]

As described above, in Japanese Patent Publication No. 3-79100, a raw material slurry (hereinafter, simply referred to as a slurry) is ejected from a single nozzle as seen from the attached drawings. No particular mention is made of nozzle clogging of the slurry.

However, in the actual operation, when the flux is manufactured, the slurry adheres to a part of the spray surface of the nozzle tip when spraying from the lance nozzle, and the uniform spray of the slurry is hindered. The droplets generated from the water fluctuate in the direction of its flight, and sometimes fly far before the initial drying of the droplets sufficiently proceeds, and the undried slurry is deposited on the inner surface of the drying tower wall that constitutes the limited drying area. It may adhere in the form of droplets, dry, solidify and deposit in that state. If the state progresses, it will not be able to withstand its own weight, and if it is exposed to a high temperature for a long time, there will be a problem that it is decarburized and turns white, partially falls off and is mixed in the flux product.

Further, the undried slurry adhering to a part of the ejection surface of the ejection nozzle tip of the lance nozzle stops growing on the nozzle tip as it is, and the abnormal ejection of the slurry is increased. Generate dripping from the part, finally dripping from the nozzle tip part,
As described above, the flux is mixed in the flux product being discharged at the lower part of the drying tower, so that the separation operation must be performed.

On the other hand, as a countermeasure against nozzle clogging (formation of deposits), Japanese Patent Application Laid-Open No. 56-129001 discloses a technique for preventing such a problem by blowing air around a slurry injection nozzle. I have. However, the present invention is fundamentally different from the purpose of preventing the adhesion of the undried slurry to the nozzle tip portion jetting surface, and does not give any suggestion about the preventive measures in the present invention as described later. Not.

In the actual operation, the undried slurry adhering to a part of the ejection surface of the ejection nozzle tip of the lance nozzle stops growing on the nozzle tip portion as it is, causing abnormal ejection of the slurry and increasing the growth. FIG. 8 shows an example of such a situation.

FIG. 8A shows the state of generation of the slurry deposit 3 on the nozzle tip portion at an initial stage (about 60).
(B) shows the process in which the deposit 3 grows (approximately 90 minutes), and (c) in FIG. FIG. 4D shows a state of falling by its own weight (about 15).
0 minutes passed). In the figure, 9 is a lance, 5 is a nozzle, and 4 is a spray slurry.

The slurry to be used in the present invention is a fluid in which solid particles are suspended in water and a predetermined amount of a binder is blended. The solid particles are particles having a predetermined particle size, for example, finely pulverized to 0.3 mm or less, but as described above, due to the inevitable mixing of coarse particles out of control. The problem is that nozzle clogging often occurs.

The lance nozzle that has clogged the nozzle is
Since the nozzle tube is constantly exposed to the high temperature atmosphere in the drying zone, and the inside of the nozzle tube is repeatedly compressed by high pressure, the slurry staying in the lance nozzle may be dried and solidified, and may not be repairable. When the nozzle clogging occurs, the operation must be stopped immediately and the nozzle must be replaced, which significantly lowers the productivity.

Further, as described above, the slurry applied to the present invention can be regarded as a fluid in which solid particles are substantially uniformly distributed in the course of passing through the supply pipe. Since it has a so-called squeezing structure for dispersing as droplets at a spread angle, that is, a so-called squeezing structure for spraying, it is regarded as a solid-liquid fluid having microscopic density, and as a result, it is inevitable that minute pulsating spray is formed.

As described above, this pulsating spray phenomenon may cause nozzle clogging when coarse particles inevitably intervening in the fluid pass through the nozzle tip portion, but are remarkable even if such a state is not reached. This causes pulsation, which partially hinders proper generation of droplets from the slurry, and causes dripping of the undried slurry from the nozzle tip as described above. As described above, the lance nozzle having the dripping in such a state must be immediately replaced and repaired, but the dripping is inevitably generated.

As described above, the hot air drying of the slurry has the above-mentioned problems, and the present invention has been made to solve such problems. It is an object to provide a method and a manufacturing device.

[0019]

The present invention adopts the following means in order to solve the above problems. (1) Vibrating the lance nozzle when spraying the raw material slurry of the mold flux for continuous casting of steel into a high-temperature atmosphere through a lance nozzle that is cantilevered in a spray-drying tower and drying the slurry. A method for producing a mold flux for continuous casting of steel, characterized by the following. (2) In a device in which a raw material slurry of a mold flux for continuous casting of steel is sprayed into a high-temperature atmosphere through a lance nozzle installed in a cantilever shape in a spray-drying tower and dried, the base of the lance nozzle is hit. A manufacturing apparatus for a mold flux for continuous casting of steel, comprising a striking device for performing the following.

(3) An apparatus for spraying a raw material slurry of a mold flux for continuous casting of steel into a high-temperature atmosphere through a lance nozzle installed in a cantilever manner in a spray-drying tower, and drying the slurry. Manufacturing the mold flux for continuous casting of steel, characterized in that the tip of the ultrasonic vibrator faces the outflowing raw material slurry, and the ultrasonic vibrator is fixed to a part of a lance nozzle outside the spray drying tower. apparatus. (4) An apparatus for spraying a raw material slurry of a mold flux for continuous casting of steel into a high-temperature atmosphere through a lance nozzle provided in a cantilever manner in a spray-drying tower to dry the slurry, The method further monitors the raw material slurry adhesion state adhering to the nozzle tip portion, compares the adhesion value with an allowable reference adhesion value, and issues a command to vibrate the lance nozzle when exceeding the reference value ( An apparatus for producing a mold flux for continuous casting of steel according to 2) or 3).

(5) The mold flux for continuous casting of steel according to any one of (2) to (4), wherein the shape of the tip end of the nozzle tip is a flat surface in the raw material slurry injection section of the lance nozzle. Manufacturing equipment. (6) The apparatus for producing a mold flux for continuous casting of steel according to (5), wherein a coating of a substance to which the raw material slurry is unlikely to adhere is formed on the flat surface at the tip of the nozzle tip. (7) The steel according to any of (2) to (6), wherein the lance portion of the lance nozzle has a double pipe structure, and a supply port and a drain port for supplying and discharging water are provided in the outer pipe. Equipment for producing mold flux for continuous casting.

[0022]

DETAILED DESCRIPTION OF THE INVENTION In view of the problems of the prior art, the present inventors have variously studied how slurry adheres to the injection nozzle tip of a lance nozzle during flux production and hinders uniform spraying of the slurry. As a result of repeated studies,
As a countermeasure, the present invention has been successfully developed.

One of the main points of the present invention is to suppress the generation of slurry adhering to the nozzle tip.
An object is to provide a similar effect by applying a certain vibration to the lance nozzle or by applying an ultrasonic vibration to the slurry.

First, FIG. 7 shows an example of a general flux manufacturing apparatus. In FIG. 7, hot air 2 from a hot air generator is used for hot air drying tower (hereinafter, referred to as “hot air drying tower”) for countercurrent drying of slurry 4.
Hot air is pumped from the top of the drying tower 1. Near the lower part of the drying tower 1, a lance 9 having a nozzle 5 at a tip end for blowing the slurry 4 penetrates the side wall from outside the drying tower, and the nozzle is directed upward at a predetermined position in the drying tower at a specific angle. And it is installed toward the center.

Further, the slurry 4 is maintained at a predetermined slurry header pressure by an annular pipe 15 surrounding the periphery of the side wall of the drying tower 1, and the slurry 4 is uniformly supplied to each lance 9. Furthermore, since the disposition position of the nozzle 5 is point-symmetrical in the drying tower 1, the slurry is sprayed almost uniformly in the drying tower 1 and the contact with the hot air 2 (normally 400 to 550 ° C.) is performed evenly. .

Further, a dried hollow granular flux of a predetermined size is stored in the lower part of the drying tower by countercurrent heat exchange with hot air, and is substantially provided by a rotary valve provided at a discharge port, for example. It is cut out continuously.
Further, a hot air exhaust unit (hollow body) 17 having been subjected to heat exchange with the slurry 4 is provided in an upper portion of a lower portion of the drying tower, and is connected to an exhaust duct 18 to suck and discharge the exhaust to the outside of the drying tower 1. it can. In the figure, reference numeral 16 denotes an observation window for constantly monitoring the state of the slurry 4 jetted from the nozzle 5, and 19 denotes an inspection port for inspecting the inside of the drying tower.

FIGS. 1 (a) and 1 (b) are exploded perspective views showing a part of the lance 9 set in the drying tower in order to show the situation thereof. It is the figure which looked at the lance 9 from the tower outside of the drying tower 1. A lance insertion port 20 is provided on the outer surface of the drying tower (not shown) for installing the lance 9, and a concave spherical member 21 is attached to the outer peripheral surface of the drying tower (not shown). Further, a base 22 for fixing the lance body 9 to the outer wall surface of the drying tower is attached to a lower portion thereof, and a receiving member 23 having a projection insertion port 24 is provided on the upper surface of the base 22. (FIG. 1B).

On the other hand, the lance main body 9 is provided with a mounting base 25 for holding the lance 9, and at a predetermined position in the longitudinal direction of the lance 9, the concave spherical surface mounted on the outer wall surface of the drying tower is provided. The lance mounting base 2 has a convex spherical member 27 that comes into contact with the member 21 by a spherical surface.
A spring 28 is interposed between the spring 5 and the spring 5. Further, a projection 26 is provided below the mounting base 25 to be inserted into the projection insertion opening 24 and fitted therein.
(A)).

Since the lance holding portion has such a configuration, when installing the lance 9 in the drying tower, first, a nozzle portion (not shown) at the tip of the lance 9 is inserted through the lance insertion port 20, and While maintaining contact between the spherical members 21 and 27, the lance mounting base 25 is pressed in the direction of the drying tower, and the lance mounting base 2 is pressed while the spring 28 is contracted.
The projection 26 located below the fifth member 5 is fitted into the projection insertion port 24 of the receiving member 23.

Thus, the spherical contact portions 21 and 27 are brought into close contact with each other by the elastic force of the spring 28, and the lance 9 is formed by the receiving member 23 with the projection fitting portions 24 and 26.
Is fixed and can maintain a predetermined nozzle setting position. In the drawing, reference numeral 29 denotes a handle provided on the lance holding base 25 so as to make it convenient for handling the lance 9. In addition, it can be used for applying vibration to the nozzle portion described later.

FIG. 2 shows a lance mounting base 25 for mounting the lance body 9 on the base 22 in FIG. 1 as described above.
Is set, and a state in which a hitting device for the lance nozzle is attached is shown.
That is, the striking device 30 (for example, a magnet hammer) is mounted on a holding base 31 extending from the base 22 via a support member 32 for height adjustment, and the striking additional portion of the striking device 30 is attached to a lance mounting base. The striking force is applied by bringing the handle into contact with the terminal surface of a handle 29 provided integrally with the handle 25. With this configuration, the striking force is transmitted as vibration to the tip of the lance nozzle, and the slurry is prevented from adhering to the nozzle tip portion. It is shaken down by the vibration, and is effective in suppressing the growth of the attached matter.

Although the present embodiment has been described using an example in which a hitting device is used, it is preferable in terms of equipment and cost that it can be implemented by remote control, but it is easy to use a hammer by hand without using such a device. Vibration can also be imparted by impact, and substantially the same effect can be obtained.

As still another example, it is possible to apply an ultrasonic vibrator to the slurry being transported and apply vibration to the slurry itself, thereby suppressing the slurry from adhering to the nozzle tip portion. For example, FIG. 3 shows a partially cutaway side view of the lance for transporting the slurry. The slurry that flows from a part of the outer surface of the lance 9 with the vibrator protector 36 suppressing noise to the surroundings is shown. By bringing the ultrasonic vibrator 35 toward 4 and applying vibration, an operation similar to the operation of the above-described impact applying device 30 can be obtained, and thus the same effect can be obtained. In the figure, reference numeral 10 denotes an inner tube, 11 denotes an outer tube, and the operation thereof will be described later.

As for the timing of applying the vibration to the nozzle tip portion, the vibration may be applied at the time of abnormality, but it is naturally possible to continuously apply the vibration, or intermittently at regular time intervals. Vibration may be applied for several seconds. Further, through a viewing window 16 shown in FIG.
The state of formation of the deposits adhering to the nozzle tip portion is constantly monitored, the monitoring result is image-processed, and compared with an allowable reference value. In order to give an operation command to the apparatus, operate the apparatus according to a predetermined vibration applying pattern, and prevent the slurry from adhering to the nozzle tip portion, an automatic vibration applying apparatus may be installed. This is shown in a simplified block diagram in FIG.

When monitoring from the viewing window, a video camera corresponding to each nozzle may be provided. In order to reduce the cost of equipment, several nozzles are monitored from one viewing window. However, it is also possible to grasp the adhesion state of the nozzle tip portion in one zone and perform the vibration adding process, and these may be appropriately selected and performed.

Next, the present inventors examined whether it is possible to prevent the slurry from adhering to the nozzle tip portion from another aspect. As a result, FIG.
As shown in (a) to (a-2), in the conventional nozzle tip portion 6, the shape of the tip portion is such that a convex slurry ejection guide portion 7 having a predetermined taper is used in order to eject the slurry with a specific spread. And found that a large amount of the slurry 4 adhered to this portion.

Then, this convex guide portion is removed,
The surface of the tip of the nozzle tip 6 was processed into a flat surface, and FIG.
As shown in (b-1 to b-2), the adhesion amount of the slurry 4 could be significantly reduced. further,
As shown in FIG. 5 (c-1 to c-2),
When the thin film 8 to which the slurry 4 was not easily adhered was coated, the amount of the adhered film was further reduced, and the amount of the conventional film was almost halved. In order to form such a coating 8, as an embodiment, it is preferable to perform a surface treatment by, for example, Teflon processing, enamel finishing, chrome plating, or the like.

Further, in the lance nozzle of the present invention, the lance is improved to a water-cooled double-amount structure. That is, as shown in FIG. 7, the lance 9 inserted into the drying tower 1 is used.
Is constantly exposed to a high temperature atmosphere by the hot air 2 in the drying tower (about 500 ° C.). Accordingly, the slurry 4 sent through the lance 9 is also heated indirectly by the heat from the lance 9, and the water in the slurry evaporates and becomes bubbles, which lowers the water in the slurry, increases the viscosity, and is easily solidified.

Therefore, the present inventors have adopted that the lance has a double pipe structure, the slurry is sent by the inner pipe, and a water supply / drain port is provided in the outer pipe to cool the lance. This is shown in FIG.
As shown in (b), the lance 9 has a double-pipe structure, and the outer pipe 11 is partitioned by a partition plate 14, for example, at the top and bottom, and a water supply port 12 is provided at a portion located outside the drying tower on the left and right of the partition plate, A drain 13 is provided on the other side. The partition plate 14 is installed up to the front of the tip nozzle portion 5 of the lance, and the left and right sides are communicated with each other, so that the water sent from the water supply port 12 passes through the communication portion and returns to the drain port 13 while returning. By cooling the lance, it is possible to prevent the slurry 4 in the inner tube 10 from being affected by heat.

[0040]

An embodiment of the present invention will be described below.
The apparatus used in the production of this example was the same as that shown in FIG. 2, and the raw material of the slurry had a general composition and produced a hollow granular flux for continuous casting.

The drying tower has a diameter of 7.1 m and a height of 7.0 m.
The hot air temperature from the hot air generator is about 450 ° C,
The amount of hot air was 180 Nm ³ / min. The lance nozzle was a water-cooled double tube nozzle, and the tip of the nozzle tip was a flat surface which had been subjected to chrome plating surface treatment. 2. Vibration to the nozzle periodically hits the handle of the nozzle mounting base with a magnet hammer.
At five-minute intervals, 12 hits were applied to one nozzle and this was continued.

The viscosity of the slurry was 150 mPa. S
The slurry solid concentration was 72%, the slurry injection pressure was 11.5 kg / cm ² , and the flow rate per nozzle was 4
The slurry was injected at an adjusted rate of 80 liters / hr.

As a result, there was almost no occurrence of deposits on the nozzle tip portion, and no abnormal ejection of slurry from the nozzle was observed. Therefore, the production of the flux generally changes favorably, and the target particle size of 400 to 13 hours has been achieved.
36 tons of hollow granule flux of 500μ were obtained, and the yield was about 97%.

[0044]

According to the present invention, it is possible to prevent the raw material slurry from adhering to the tip of the lance nozzle, or even if it adheres, the amount thereof can be significantly reduced and the growth of the adhering substance can be prevented. . In addition, since abnormal slurry injection from the nozzle can be reduced, no droplets of the undried slurry adhere to the inner surface of the drying tower wall. For this reason, it is possible to avoid mixing defective products into the produced flux, and it is possible to produce a good flux.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an example for setting a lance nozzle.

FIG. 2 is a schematic perspective view of the impact device according to the present invention installed with the lance nozzle mounted.

FIG. 3 is a side cross-sectional view of an ultrasonic transducer facing slurry.

FIG. 4 is a block diagram showing a motion for automatically adding vibration.

FIG. 5 is an enlarged view of a nozzle tip portion.

FIG. 6 is a view showing a water-cooled double tube structure of the present invention.

FIG. 7 is a schematic side view showing an example of a drying tower.

FIG. 8 is a schematic view showing an example of a growth state of slurry attached to a nozzle tip in a drying tower.

[Description of Signs] 1 Hot-air drying tower 2 Hot-air (air) 3 Attached matter 4 Raw material slurry 5 Nozzle 6 Nozzle tip 7 Slurry injection guide 8 Coating 9 Lance 10 Inner pipe 11 Outer pipe 12 Water supply port 13 Drain port 14 Middle partition Plate 15 Annular tube 16 Viewing window 17 Hot air exhaust unit 18 Exhaust duct 19 Inspection port 20 Lance insertion port 21 Concave spherical member 22 Base 23 Receiving member 24 Projection insertion port 25 Lance mounting base 26 Projection 27 Projecting spherical member 28 Spring 29 Handle 30 Striking device 31 Holder 32 Support member 34 Transducer protector 35 Ultrasonic transducer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-1-274859 (JP, A) JP-A-62-191033 (JP, A) JP-A-3-151037 (JP, A) JP-A-7-107 795 (JP, A) JP-A-4-9409 (JP, A) JP-A-10-166122 (JP, A) JP-A-10-146657 (JP, A) JP-A-60-87960 (JP, A) JP-A-10-58104 (JP, A) JP-A-61-150752 (JP, A) JP-A-52-123330 (JP, A) JP-A-9-57407 (JP, A) JP-B-3-79100 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11/108 B22D 11/07 C21C 7/076 B01J 2/04

Claims (7)

(57) [Claims] When a raw material slurry of a mold flux for continuous casting of steel is sprayed into a high-temperature atmosphere through a lance nozzle provided in a cantilever manner in a spray-drying tower to be dried, vibration is applied to the lance nozzle. A method for producing a mold flux for continuous casting of steel, the method comprising: 2. A device for spraying and drying a raw material slurry of a mold flux for continuous casting of steel into a high-temperature atmosphere through a lance nozzle provided in a cantilever manner in a spray-drying tower. An apparatus for producing a mold flux for continuous casting of steel, comprising a hitting device for hitting the steel. 3. An apparatus for spraying and drying a raw material slurry of a mold flux for continuous casting of steel into a high-temperature atmosphere through a lance nozzle provided in a cantilever manner in a spray-drying tower. An ultrasonic vibrator fixed to a part of a lance nozzle outside the spray-drying tower, with the leading end of the ultrasonic vibrator facing the raw material slurry to be manufactured. . 4. An apparatus for drying by spraying a raw material slurry of a mold flux for continuous casting of steel into a high-temperature atmosphere through a lance nozzle installed in a cantilever manner in a spray drying tower, wherein the spray drying tower has It monitors the raw material slurry adhered to the nozzle tip from the viewing window, compares the adhered value with the allowable reference adhered value, and issues a command to vibrate the lance nozzle when it exceeds the reference value. The apparatus for producing a mold flux for continuous casting of steel according to claim 2 or 3. 5. The mold flux for continuous casting of steel according to claim 2, wherein a shape of a tip end portion of the nozzle tip in the raw material slurry injection section of the lance nozzle is a flat surface. manufacturing device. 6. The apparatus for producing a mold flux for continuous casting of steel according to claim 5, wherein a coating of a substance to which the raw material slurry is unlikely to adhere is formed on the flat surface at the tip of the nozzle tip. 7. The lance nozzle according to claim 2, wherein the lance portion of the lance nozzle has a double pipe structure, and a supply port and a drain port for supplying and discharging water are provided in the outer pipe. Equipment for producing mold flux for continuous casting of steel.