JP2000219545A - Process and equipment for producing water granulated slag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce high quality water granulated slag by stabilizing quenching and granulating conditions in the process. SOLUTION: This production process comprises spraying cooling water on molten slag which is discharged from a blast furnace and allowed to flow through a slag trough, from plural nozzles (1)-(7) arranged on the periphery of the slag trough, wherein: one portion of the cooling water heated in a hot water tank 20 is transferred to a water supply vessel 22 through a cooling tower 21 and the other portion is directly transferred to the water supply vessel 22 and the temperature of the cooling water in the water supply vessel 22 is controlled within the range of 70-85 deg.C by adjusting the flow rate ratio of the cooling water portion transferred through the cooling tower 21 to the cooling water portion directly transferred; and also, solenoid valves V1-V4 are placed in a water supply pipeline system extending from the water supply vessel 22 to the nozzles (1)-(7) through a header 11 and the group of the nozzles (1)-(7) is divided into four blocks. Thus, the solenoid valves V1-V4 are opened correspondingly to the flow rate of molten slag flowing through the slag trough to change the spray pattern of the cooling water from the nozzles (1)-(7).

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 granulated slag used as a raw material for cement, construction material, etc., by blowing molten slag discharged from a blast furnace.

[0002]

2. Description of the Related Art Blast furnace slag is reused as slowly cooled slag, granulated slag, and the like. Slow-cooled slag is crushed and sized and used for roadbed material, concrete aggregate, rock wool raw material, fertilizer raw material, and the like, and granulated slag is used for cement raw material, soil improver, fine aggregate, and the like. Slow-cooled slag is used for roadbed materials, etc. after slowly cooling the molten slag discharged from the blast furnace, whereas granulated slag is obtained by spraying a large amount of water onto the molten slag and rapidly cooling and crushing it. Manufactured. Specifically, as shown in FIG. 1, molten slag is separated into slag gutters 3 from hot metal discharged from a blast furnace main body 1 to a tapping gutter 2, and the separated molten slag is cooled by a large amount from a blow box 4. Rapid cooling and crushing by spraying water.

As shown in FIG. 2, the granulated slag has a particle structure in which open cells b and closed cells c are dispersed in a substantial portion a mainly composed of glass, and the higher the vitrification rate, the higher the quality. I have. Since the vitrification rate is affected by the quenching condition of the molten slag, the quenching condition is made constant by controlling the injection amount of cooling water according to the flow rate of the molten slag. Further, in Japanese Patent Application Laid-Open No. Hei 5-31213, the blowing nozzle is divided into a plurality of zones in the width direction of the slag gutter 3 and the blowing nozzle is changed so as to cancel the flow rate change of the molten slag fluctuating in the width direction of the slag gutter 3. Is controlled.

[0004]

The granulated slag is mixed with auxiliary materials such as gypsum and limestone after drying, and further pulverized by a crusher to be used for various purposes. Therefore, excellent grindability is also an important requirement in determining the quality of granulated slag. The crushability is better when the number of open bubbles b, closed bubbles c, and the like dispersed in the granulated slag particles is larger. When high-temperature spray water is sprayed on the granulated slag, a gas generation reaction is promoted, and slag particles in which a number of bubbles are dispersed are obtained. However, the injection water having an excessively high temperature has a low cooling capacity for the granulated slag, and the obtained granulated slag has a large particle size. Moreover, since a large amount of cooling water is used for granulation,
It is not easy to control water temperature.

[0005]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem. A path for directly sending cooling water from a hot water tank to a water supply tank is provided, and the amount of water from the cooling tower is reduced. By controlling the ratio of the cooling water to the molten slag to an appropriate temperature by controlling the ratio of the molten slag to the direct water supply amount, and by changing the injection pattern according to the flow rate of the molten slag flowing through the slag gutter, rapid cooling of the molten slag It is intended to stabilize the crushing conditions and produce high-quality granulated slag.

In order to achieve the object, the method for producing granulated slag of the present invention is characterized in that the molten slag discharged from the blast furnace and flowing through the slag gutter is sprayed with cooling water from a plurality of nozzles arranged around the slag gutter to granulate the granulated slag. When manufacturing slag, the cooling water heated in contact with the molten slag is sent from the hot water tank to the water tank via the cooling tower and directly to the water tank, and is directly sent from the cooling water via the cooling tower and the hot water tank. The temperature of the cooling water is adjusted to 70 to 85 ° C. according to the flow rate of the cooling water, and the solenoid valve provided in the water supply pipe from the water supply tank to the nozzle via the header is opened in accordance with the increase in the flow rate of the molten slag. Is characterized by changing the ejection pattern of.

[0007] The apparatus used in this method includes a hot water tank, a cooling tower in which cooling water is sent from the hot water tank via a normal path and sent to a water supply tank, and a water supply tank in which cooling water is sent from the hot water tank via a direct path. And a plurality of water supply pumps for sending cooling water from the water supply tank to the header, a plurality of nozzles arranged around the slag gutter, a solenoid valve provided on a water supply pipe connecting the header and the nozzle, and hot water from the header. And a return path for returning the cooling water to the tank.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A granulated slag manufacturing apparatus according to the present invention comprises:
For example, as shown in FIG. 3, a blowing box 10 having a plurality of nozzles arranged around a slag trough 3 through which a molten slag S flows.
It has. Nozzle, from above, nozzle ~
, From below, the nozzle blows cooling water to the molten slag S from the side. Each nozzle is connected to the hot water tank 20, the cooling tower 21 and the water supply tank 22 by a piping system shown in FIG. The cooling water heated by the contact with the molten slag is temporarily stored in the hot water tank 20 and sent to the cooling tower 21 via the normal route A, and a part is sent to the water supply tank 22 via the direct delivery route B. . The direct path B, and flow control valve V ₅ are provided.

[0009] and opening adjustment of the flow rate control valve V _5, by controlling the ratio of the amount of water sent directly with the amount of water sent from the hot water tank 20 to the cooling tower 21 to the water supply tank 22, 70-85
Water temperature is properly controlled in the range of ° C. The cooling water maintained at an appropriate temperature suppresses a decrease in the vitrification rate, promptly promotes a foaming reaction when coming into contact with the molten slag, and improves the crushability of the granulated slag. If the water temperature does not reach 70 ° C., the foaming reaction time becomes short, and the grindability deteriorates. On the other hand, at a water temperature exceeding 85 ° C., the cooling capacity for the molten slag is reduced to lower the vitrification rate of the granulated slag, and the vapor pressure is increased, thereby increasing the risk of generating cavitation in the water supply pump 24.

The cooling water in the water supply tank 22 is supplied to a water supply pump 24.
By pressure to the header 11. Header 11 is connected to the nozzles - through the water supply pipe 12 ₁ to 12 _7. Water supply pipes 12 _1, 12 ₄ of the motorized valve V ₄ based pipe, the water supply pipe 12 _third electric valve V _3, motorized valve V ₁ to the water supply pipe 12 _5, based tube of the water supply pipe 12 _2, 12 _6, 12 ₇ the motorized valve V ₂ is provided, which divides the nozzle-to four blocks. Each of the solenoid valves V _{1 to} V ₄ is opened and closed according to the flow rate of the molten slag S flowing through the slag gutter 3. Electromagnetic valve V ₁ ~V
By opening and closing ₄ , four types of injection patterns can be adopted. The header 11 is further connected to a hot water tank 20 via return paths C and D. The amounts of water passing through the return routes C and D are controlled by flow control valves V ₆ and V ₇ , respectively.

Each nozzle is turned on and off according to the flow rate of the molten slag S as shown in FIG. In between taps (a), it opens the solenoid valve V _1, by injecting cooling water from the nozzle, waiting in吹製state. Molten slag S
In the initial stage of discharging the slag, the flow rate of the molten slag S flowing through the slag gutter 3 is small, so that the amount of the injected water is set to be suppressed. Specifically, in order to prevent overload on the pumps, the flow rate control valves V ₆ and V ₇ of the return paths C and D are opened to keep the discharge flow rate constant and suppress pressure fluctuation. Further, it is preferable that the entire amount be sent from the hot water tank 20 to the water supply tank 22 via the direct feeding path B to prevent the temperature of the cooling water from dropping. In吹製initial stage of the slag trough 3 is molten slag S starts to flow (b), it opens the solenoid valve nozzle V _2, nozzle, for injecting cooling water from ~. In addition, the flow rate of the molten slag S flowing through the slag gutter 3 is detected by performing image processing on an imaging result of an industrial camera, measuring the temperature of the slag gutter 3, and the like. Alternatively, the flow rate of the molten slag S can be calculated using a weigher provided on a conveyor for transporting the produced granulated slag.

[0012] In step the flow rate of the molten slag S is steady state (c), the solenoid valve V ₃ is also opened in addition to the solenoid valves V _1, V _2, to add cooling water jetting from the nozzle. In addition, the ratio of the amount of cooling water flowing through the normal path A and the direct-feed path B is adjusted to appropriately maintain the temperature of the cooling water sprayed on the molten slag S. Further, if the flow a large amount of molten slag S (d), the solenoid valve V ₄ is also opened, to inject cooling water from all of the nozzles ~. The number of operating water supply pumps 24 provided in the water supply tank 22 is increased or decreased according to the cooling water injection amount.
As described above, by adjusting the injection mode and the injection water amount in accordance with the flow rate of the molten slag S flowing through the slag gutter 3, appropriate blowing conditions are maintained. Further, by controlling the flow rate of the hot water sent from the hot water tank 20 to the water supply tank 22 via the direct feeding path B, the temperature of the cooling water sprayed on the molten slag is appropriately managed.

The higher the temperature of the cooling water blown to the molten slag S, the higher the temperature of 2N ₃ ⁻ + between the molten slag S and the cooling water.
_{H 2 0 → H 2 + N} 2 + O 2 - gas generating reaction proceeds actively such, generated gas for dispersing the slag particles, improves the crush resistance of the granulated slag. However, if the water temperature is too high, a vapor film is formed around the molten slag S, the cooling is slow, and the vitrification rate is reduced. As a result of investigation and research by the present inventors, it has been found that when the temperature of the cooling water is maintained at 70 to 85 ° C., granulated slag having a vitrification rate of 98% or more and excellent in crushability can be obtained. The appropriate water temperature of 70 to 85 ° C. can be easily achieved by opening and closing the return paths C and D according to the flow rate of the molten slag S, controlling the number of operating water supply pumps 24, controlling the flow rate to the water supply tank 23, and the like. In this respect, in a piping system having only the direct feed path B, the cooling water temperature must be adjusted only by controlling the temperature in the hot water tank 20, and is not suitable for controlling the temperature of a large amount of cooling water required for water granulation.

[0014]

EXAMPLE Hot metal and molten slag are discharged by alternately using three tap holes provided in a blast furnace, and cooling water is injected into molten slag S diverted from the tapping trough 2 to the slag trough 3 by discharging. Granulated slag was produced. As shown in FIG. 6, the operating parameters at this time are as follows: opening and closing of return paths C and D, operating number of water supply pumps 24, and flow rate control to water supply tank 23 are performed in accordance with the flow rate of molten slag S, and water temperature is controlled. The spray pattern was switched from a to b to c to d (Fig. 5) while maintaining the temperature in the range of 70 to 85C. The specific surface area of the obtained granulated slag was measured by the Blaine method specified in JIS R5201. As can be seen from the measurement results in FIG. 7, when the spray pattern was changed using cooling water at 70 ° C. or higher, fine granulated slag having a specific surface area exceeding 4100 cm ² / g was obtained. The vitrification rate of this granulated slag was 98% or more, and was a high-quality raw material used as cement, soil conditioner, fine aggregate, and the like.
On the other hand, when the molten slag S was granulated without changing the water temperature control and the spray pattern (×), the specific surface area became larger as the high-temperature cooling water was used. The granulated slag had a surface area. Even when the water temperature was controlled (○), the granulated slag had a smaller specific surface area as compared with the case where the spray pattern was changed (●).

[0015]

As described above, in the present invention, when producing cooling granulated slag by injecting cooling water into molten slag flowing through a slag gutter, the amount of water directly sent from a hot water tank to a water supply tank is controlled. At the same time, the spray pattern of the cooling water at a water temperature of 70 to 85 ° C. is switched according to a change in the flow rate of the molten slag. As a result, granulated slag having excellent crushability and high vitrification rate is stably produced, and is used as a high-quality raw material for cement, soil conditioners, fine aggregate, and the like.

[Brief description of the drawings]

Fig. 1 Around a blast furnace where granulated slag production equipment is installed

Fig. 2 Particle structure of granulated slag

FIG. 3 shows a blow box used in the present invention.

Fig. 4 Cooling water piping system

FIG. 5 Injection pattern changed according to the flow rate of molten slag

FIG. 6: Changes in operation specifications adopted in the example

FIG. 7 is a graph showing the effect of cooling water temperature and spray pattern on the specific surface area of granulated slag.

[Explanation of symbols]

1: Blast furnace body 2: Tapping gutter 3: Slag gutter 4,
10:吹製a box 11: Header 12 ₁ to 12 _7: feed water pipe 20: hot water tank 21: Cooling tower 22: Water tank 24: Water pump ~: nozzles A: Normal route B: direct path C, D: return path S : molten slag V ₁ ~V _4: solenoid valve V ₅ ~V
₇ : Flow control valve a: Vitreous substantial part b: Open bubble c: Closed bubble

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshio Yanagawa 111-1 Showa-cho, Kure-shi, Hiroshima Nisshin Steel Co., Ltd. Inside Kure Works (72) Inventor Koji Sumiooka 111-1 Showa-cho, Kure-shi, Hiroshima New Steel Co., Ltd. Kure Works (72) Inventor Gochio Shimomine 11-1, Showa-cho, Kure-shi, Hiroshima F-term in Nissin Steel Co., Ltd. Kure Works 4G012 JH03

Claims (2)

[Claims] 1. A method of producing granulated slag by spraying cooling water from a plurality of nozzles disposed around a slag gutter onto a molten slag discharged from a blast furnace and flowing through the slag gutter, the temperature of the molten slag being raised by contact with the molten slag. The cooling water is sent from the hot water tank to the water supply tank via the cooling tower and directly to the water supply tank, and the temperature of the cooling water is set to 70 to 85 depending on the flow rate ratio of the cooling water via the cooling tower and the cooling water directly sent from the hot water tank. A method for producing granulated slag in which the temperature is adjusted to ° C., and a solenoid valve provided in a water supply pipe extending from a water supply tank to a nozzle via a header is opened in accordance with an increase in the flow rate of the molten slag to change a spray pattern of cooling water. 2. A hot water tank, a cooling tower in which cooling water is sent from the hot water tank via a normal path and sent out to a water supply tank, a water supply tank in which cooling water is sent from the hot water tank through a direct path, and cooling from the water supply tank. A plurality of feed pumps that send water to the header, a plurality of nozzles arranged around the slag gutter,
A granulated slag producing apparatus comprising: an electromagnetic valve provided in a water supply pipe connecting a header and a nozzle; and a return path for returning cooling water from the header to a hot water tank.