JPH11236255A - Production of coarse-grained hard watergranulated blast furnace slag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply and efficiently produce the hard water-granulated blast furnace slag without requiring any complex equipment by spraying water of a specified temp. on molten blast furnace slag to quench the slag. SOLUTION: In this production that comprises spraying water on blast furnace slag to quench the slag with the water, the slag is subjected to water spray granulation with quenching water of 60 to 80 deg.C, to produce coarse-grained water-granulated slag. However, generally, in the coarse-grained water-granulated slag thus produced, hard water-granulated slag and soft water-granulated slag coexist. Therefore, in order to produce the objective coarse-grained hard water-granulated slag that needs to have a high specific gravity, the ratio of water to slag i.e., the ratio of (quenching water flow rate, (weight (ton) of water)/hr) to (molten blast furnace slag flow rate, (weight (ton) of slag/hr) is adjusted to>=30 to produce hard water-granulated slag having a >=1.35 kg/L mass of unit volume. At this time, when the water temp. in a water granulation vessel in which water immediately after it is used for water granulation and the water-granulated slag coexist, is >95 deg.C, the amount of generated steam at the time of performing water spray granulation and quenching of the slag, is increased and accordingly, the volume of closed pores in the water-granulated slag after quenching it is increased to decrease the specific gravity in absolute dry condition of the slag and therefore, to decrease the mass of unit volume of the water-granulated slag produced. Thus, a water temp. in the water granulation vessel is preferably <=95 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing granulated granulated blast furnace slag for concrete, and more particularly to a granulated hard granulated slag capable of producing granulated granulated granulated blast furnace slag for concrete. And a method for producing the same.

[0002]

[Prior Art] Blast furnace slag is about 2,300 annually in Japan alone.
Of which are 14 million tons, of which more than 60%
The above is the granulated slag produced by the blowing method in which water is directly blown onto the molten slag and rapidly cooled. In this case, circulating water is generally used as the water, and the quality of the water may be any water that does not contain components that remain in the manufactured granulated slag and adversely affect the use of the granulated slag.

[0003] Granulated slag is classified into soft granulated slag for cement raw materials and hard granulated slag for fine aggregate for concrete according to its properties. The standard of hard granulated slag for fine aggregate for concrete is specified in JIS A 5011. The method currently used as a method for manufacturing hard granulated slag is as follows: once the slag is placed in a slag pot, and then granulated by a granulation facility provided in a location separate from the blast furnace. Of a furnace-front method that sorts slag with high specific gravity from granulated slag produced by the soft granulated production facility
It has been implemented in a scheme.

[0004] When hard granulated slag is used as fine aggregate for concrete, it is rare to use only hard granulated slag. That is, in general, hard granulated slag is partially mixed with natural sand for use. This is due to the problem that hard granulated slag has hydraulic properties, reacts with moisture during storage and solidifies, and hard granulated slag alone is not suitable for long-term storage.

The particle size distribution of fine aggregate is determined by JIS, and in many cases, the standard cannot be satisfied only with natural sand, and the particle size distribution is adjusted by mixing crushed sand or the like. Hard granulated slag is used as a substitute for crushed sand and the like, and a grain size corresponding to the grain size of natural sand is required. That is, when the particle size of the natural sand is fine, coarse particles are required, and when the particle size of the natural sand is coarse, fine particles are required.

When fine granulated hard granulated slag is required, the required quality can be easily satisfied by crushing the hard granulated slag and adjusting the particle size. However, when coarse granulated hard granulated slag is required, it is necessary to coarsen the particle size of the raw slag. There is no prior art which mentions a method of coarsely granulating hard granulated slag, but as a device and method for separately producing hard granulated slag and soft granulated slag, Japanese Patent Publication No. 6-39
No. 340 is disclosed.

[0007] In this publication, the injection nozzle for blowing water for cooling slag is divided into four nozzles, and a structure capable of independently controlling the water pressure of each nozzle is adopted. It is described that the particle size becomes coarse when the water pressure of a cooling water nozzle which is first hit is reduced. However, in the case of the above-mentioned method, the equipment becomes complicated, and it is necessary to control the water pressure of each injection nozzle within an appropriate range.In terms of equipment and operation management, the hard granulated slag is efficiently granulated with simple equipment. There was a need for a way to make it more sophisticated.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and efficiently manufactures coarse-grained hard granulated slag with simple equipment without requiring complicated equipment. It is an object of the present invention to provide a method for producing coarse-grained hard granulated slag that can be used.

[0009]

Means for Solving the Problems The first invention is to rapidly cool a molten blast furnace slag with water to produce hard granulated slag.
This is a method for producing coarse-grained hard granulated slag characterized by blowing at a cooling water temperature of 60 to 80 ° C. The second invention is characterized in that when the molten blast furnace slag is quenched with water and hard granulated slag is produced, the water temperature is adjusted so that the cooling water temperature is in the range of 60 to 80 ° C, and blown. This is a method for producing a coarse-grained hard granulated slag.

In the first and second aspects of the present invention, a method for producing granulated hard slag of a furnace front type is applied as a method for producing a coarse-grained hard granulated slag, and the above-described conditions are further satisfied. In addition, cooling water flow rate (t-cooling water / hr)
/ Molten blast furnace slag flow rate (t-slag / hr) ≧ 30 and water temperature in the granulation tank ≦ 95 ° C. It is preferable to blow-blowing. In this case, the flow rate of the cooling water and the production amount of the granulated slag were measured, and the flow rate of the molten blast furnace slag was determined from the production amount of the granulated slag, and the cooling water flow rate (t-cooling water / hr) / the molten blast furnace slag flow rate
(t-slag / hr).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present inventors first investigated the relationship between the production conditions and the particle size of the granulated slag in a general soft granulated slag production facility. That is, after draining the granulated slag, the granulated slag was sampled every 10 minutes while being transported to the hopper, and the particle size distribution after drying was measured.

Based on the measurement results obtained, the coarse grain ratio (FM
Values) and slag temperature, slag flow rate, water / slag ratio, cooling water temperature (: blowing water temperature), and the like. In addition,
The above-mentioned cooling water temperature (: blowing water temperature) is the temperature of the cooling water jetted to the molten blast furnace slag, and is the water temperature measured at the cold water tank 15. The above-mentioned coarse grain ratio (FM value)
Aggregate is 80,40,20,10,5,2.5,1.2,0.6,0.3,0.15mm Sieve granulated sand (: granulated slag) with a sieve, and the cumulative total of granulated sand remaining on each sieve It is defined as the sum of percentages and this value divided by 100.

As a result, the relationship between the cooling water temperature and the coarse particle ratio shown in FIG. 5 was obtained, and it was found that the higher the cooling water temperature, the higher the coarse particle ratio. In particular, when the cooling water temperature is 60 ° C or higher, the coarse particle ratio exceeds 3.2, and the particle size sharply increases. There was no clear relationship between the other survey items and the coarse grain ratio.

However, as shown in FIG. 5, the soft granulated slag production equipment has a specific gravity (: unit volume mass ≧ 1.35 kg / l) corresponding to hard granulated slag (in the figure: ○).
Some have low specific gravity (: unit mass <1.35 kg / l) and do not become hard granulated slag (in the figure: ●). If the cooling water temperature is as low as 40 ° C. or lower, hard granulated slag tends to be formed, and if the cooling water temperature exceeds 80 ° C., hard granulated slag is not formed.

On the other hand, when the cooling water temperature is in the range of 60 to 80 ° C.,
Hard granulated slag and soft granulated slag are mixed, and the water temperature is such that granulated slag having a coarse particle size can be obtained. Therefore, in order to apply the method of the present invention to the pre-furnace method to produce coarse hard granulated slag, it is necessary to produce granulated slag having a high specific gravity. The present inventors have proposed a flow rate of cooling water (blown water) (t-cooling water / hr) / flow rate of molten blast furnace slag (t-slag / hr) when blowing granulated slag in the pre-furnace method. / Slag ratio) and the unit volume mass of the granulated slag were investigated. As shown in FIG. 3, the unit volume mass ≧ 1.35 kg / l was achieved under the condition of water / slag ratio ≧ 30. Was found.

On the other hand, even if the water / slag ratio is 30 or more,
When the water temperature in the granulator exceeds 95 ° C., the unit mass decreases as shown in FIG. The reason may be due to the following phenomenon. The unit mass of the granulated blast furnace slag, that is, the bulk specific gravity, is determined by two factors.

One is the amount of closed pores in the granulated slag, and the other is due to the particle size distribution and appearance.
The amount of closed pores affects the absolute density (apparent density), which is the density of the granulated slag itself. According to previous research results, a mixed gas of hydrogen gas and nitrogen gas was present in these closed pores. Is known to be.

According to the measurement results of the present inventors, H ₂ : N ₂ =
It was found to be present in a 3: 1 ratio. This closed pore
Water that comes into contact with the slag at the time of cooling the molten slag becomes steam and dissolves in the slag, and is caused by a mixed gas of hydrogen gas and nitrogen gas generated by reacting with dissolved nitrogen in the slag.

From this fact, in a granulation tank where water and slag coexist immediately after granulation, when the water temperature exceeds 95 ° C.,
Since a large amount of steam is generated during blow-blowing cooling and the amount of closed pores after cooling increases, the absolute specific gravity decreases and the unit volume mass decreases. Therefore, in the present invention, the water temperature of the granulation tank is preferably 95 ° C. or lower.

The term “water granulation tank” in the present invention refers to a tank for receiving a mixture of slag and water after granulation in a granulated slag production facility. As described above, in order to apply the method of the present invention to the pre-furnace method to produce coarse-grained hard granulated slag,
The water / slag ratio defined above is 30 or more, and the water temperature of the granulation tank is
Preferably it is 95 ° C or lower.

[0021]

EXAMPLES The present invention will be described below more specifically based on examples. Pre-furnace method to sort slag with high specific gravity of granulated slag produced by a soft granulated slag production facility directly connected to a blast furnace (Example 1), and after once receiving slag in a slag pan, separate from the blast furnace The present invention was carried out by two methods, an out-of-furnace method (Example 2) in which water was granulated by a water granulation facility provided at the place.

(Embodiment 1) In the above-mentioned furnace front system,
The invention has been implemented. FIG. 6 shows a pre-furnace method according to the present invention.
The outline of the granulated slag production facility is shown by a side view. Figure
In 6, 6, 1 is a blast furnace, 2 is a tap hole, 3 is a tapping gutter, 4 is
Slug gutter, 5 is a cooling water (: blowing water) spray nozzle, 6 is a blow
Box making, 7 is cooling water (: blowing water), 8 is a granulation tank, 9 is smoke
, 10 is a hot water tank, 11 is a circuit having a cylindrical filter 11a.
Drainer, 12 for distributor, 13a, 13b for base
Conveyor, 14 is a thermocouple, 15 is a cold water tank, 16 is a cooling tower,
17 is a weighing device, 18a and 18b are product hoppers, 19 is a switch
Dampers, 20 and 30 are liquid feed pumps, 21 is a flow control valve, 22 is
Cooling water (blowing water) flow meter, 23 is a control unit, 31a is
Liquid piping, 31b is liquid supply bypass piping, 32a, 32b is switchable
Valve, f₁Is the flow direction of the molten blast furnace slag, f_TwoIs cooling
Flow direction of water (blowing water), f _ThreeIs how to transfer granulated slag
Direction, f_FourIndicates the flow direction of makeup water.

In the granulated slag manufacturing equipment shown in FIG. 6, cooling water (blown water) 7 is sprayed on the molten slag falling from the blowing box 6 to granulate the water, and the cooled and solidified slag is granulated together with the water. Enter tank 8. Then, after the granulated slag and water are separated by the cylindrical filter 11a of the rotary draining device 11, the granulated slag is transferred to the product hoppers 18a, 18b by the belt conveyors 13a, 13b.
Transport by b.

In the middle of the belt conveyor 13b, a weighing device 17 is provided.
Is provided, and the production amount of granulated slag is continuously measured. The granulated slag on the belt conveyors 13a and 13b has high water content, and the value obtained by subtracting the water content is the actual flow rate of the molten blast furnace slag discharged from the taphole 2. The above-mentioned molten blast furnace slag flow rate, the water content ratio in the granulated slag after draining by the rotary draining device 11 does not change so much even if the production amount and the blowing water amount of the granulated slag are changed. Determine the correction value by measuring the water content ratio of
It was obtained by performing a correction in the controller 23 by subtracting a certain percentage of water content from the granulated slag production volume.

The water separated from the granulated slag accumulates in the hot water tank 10, is sent to the cooling tower 16 by the liquid sending pump 30 and is cooled, and the cooled water is stored in the cold water tank 15. When the method of the present invention was carried out, the blast furnace tapping rate was 7800 to 8000 ton / day, and the slag ratio was about
320 kg / ton-pig, tapping temperature was 1495 to 1505 ° C. In order to apply the method of the present invention to the pre-furnace method to produce coarse-grained hard granulated slag, it is necessary to produce granulated slag having a high specific gravity as described above.

Therefore, in the present embodiment, granulated slag having a high specific gravity was manufactured based on the above-described manufacturing conditions of the hard blast furnace granulated slag found by the present inventors. That is, the production conditions of the hard granulated slag were as follows: cooling water (blowing water) flow rate / melting blast furnace slag flow rate [water / slag ratio] ≧ 30, and water temperature of the granulation tank 8 ≦ 95 ° C. The flow rate of the cooling water (blowing water) indicates the amount of cooling water injected from the water injection nozzle 5 per unit time, and the flow rate of the molten blast furnace slag is supplied from the slag gutter 4 to the blowing box 6. And the flow rate of the molten blast furnace slag.

In the case of this equipment, it takes about 3 minutes for the slag to reach the weighing device 17 after the slag is granulated in the blow box 6, and the value obtained by subtracting the moisture from the weighed value is 3 minutes before. Of the molten blast furnace slag. This equipment is equipped with two product hoppers (product hopper 18a and product hopper 18b) as described above, and produces hard granulated slag under the following conditions in the early stage of tapping and puts it into product hopper 18a. Thereafter, the hopper was switched by the switching damper 19, and the soft granulated slag produced in the latter half of tapping was put into the product hopper 18b.

Specifically, the flow rate of cooling water (the flow rate of blowing water)
Was set to the condition of 50 m ³ / min and started blowing, the granulated slag of high specific gravity produced was stored in the product hopper 18a, and when the molten blast furnace slag flow increased and reached an average of 1.7 ton / min ,
The switching damper 19 was driven by a signal from the control device 23, and the product hopper to be charged was switched to the product hopper 18b.

The temperature of the cooling water (blowing water) 7 is adjusted by passing the cooling water through the cooling tower 16 when lowering the cooling water temperature, and stopping the cooling tower fan 16a when raising the cooling water temperature. This was performed by passing the liquid from the water tank 10 to the cold water tank 15 through a liquid sending bypass pipe 31b. In this embodiment, when the temperature of the cooling water 7 exceeds 80 ° C., the water temperature of the granulation tank 8 becomes 95 ° C.
As described above, as a result of the temperature adjustment of the cooling water 7, the temperature of the granulation tank 8 did not exceed 95 ° C. during the production of the hard slag.

The temperature of the cooling water 7 (blowing water temperature) is the temperature of the cooling water jetted to the molten blast furnace slag.
This is the water temperature measured at the location of the cold water tank 15. FIG. 1 shows the relationship between the cooling water temperature during the production of hard slag and the coarse particle ratio of the hard granulated slag extracted from the product hopper 18a. The cooling water temperature gradually increased during the production of the hard granulated slag, and was represented by a line, and the relationship between the intermediate temperature and the coarse particle ratio was plotted.

As shown in FIG. 1, when the cooling water temperature is low (Comparative Example), the coarse particle ratio is low, but by adjusting the cooling water temperature to 60 to 80 ° C. according to the method of the present invention, Hard granulated slag having a high coarse particle ratio was obtained (Example of the present invention). The hard granulated slag produced in the present invention example and the comparative example shown in FIG. 1 each had a unit volume mass of 1.35 kg.
/ l or more, and by crushing the obtained hard granulated slag and adjusting the particle size, each of the hard granulated slags satisfied the hard granulated slag standard having a unit mass of 1.45 kg / l or more.

(Example 2) The present invention was carried out in the above-mentioned out-of-furnace method. FIG. 7 is a side view showing an outline of an out-of-furnace type granulated slag manufacturing facility in which the present invention is implemented. In FIG. 7, reference numeral 50 denotes a slag pot, 51 denotes a molten blast furnace slag, 52 denotes a tundish, 53 denotes a cold runner, 54 denotes cooling water (blowing water), 55 denotes a water injection nozzle, and 56 denotes a product slag.

A tundish 52, a cold runner 53 and a water injection nozzle 55 shown in FIG. 7 were provided in a slag cooling yard, and a hard granulated slag production test was performed. The cold water tank, hot water tank, cooling tower, and liquid transfer pump that control the temperature of the cooling water
The test was conducted by using the above-mentioned furnace-front equipment, extending the piping, and connecting to the water injection nozzle 55.

The temperature of the cooling water (blowing water) 54 was adjusted in the same manner as in the furnace front method of the first embodiment. The slag flow rate is set to a predetermined tundish diameter based on the relationship between the tundish diameter and the outflow velocity obtained in advance, and
It was made constant at 2 ton / min. The flow rate of the cooling water injected from the water injection nozzle 55 was 40 m ³ / min (constant), and the amount of waste from the pot was 30 tons / time.

FIG. 2 shows the relationship between the temperature of the cooling water (blowing water) 54 during the production of hard slag and the coarse particle ratio of the collected hard granulated slag. The temperature of the cooling water (blowing water) 54 is the temperature of the water before being blown into the cold runner 53, measured in the cold water tank 15. As shown in FIG. 2, when the cooling water temperature is low (Comparative Example), the coarse particle ratio is low, but by adjusting the cooling water temperature to 60 to 80 ° C. according to the method of the present invention, the coarse particle ratio is reduced. A hard granulated slag with high hardness can be manufactured (Example of the present invention).

Also, as shown in FIGS. 1 and 2, hard granulated slag having a coarser grain size could be produced by the out-of-furnace granulation method than by the pre-furnace granulation method. This is presumed that, in the case of the out-of-furnace method, since the slag is once received in the pot, the slag temperature before granulation is low, and a coarser slag can be obtained.

[0037]

According to the present invention, it is possible to efficiently produce coarse-grain hard granulated slag with simple equipment without requiring complicated equipment. Also, no major equipment modification is required for existing granulated slag production equipment, and it is possible to produce coarse-grained hard granulated slag by limiting the cooling water temperature within the specified range. Was.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the cooling water temperature during hard granulated slag production and the coarse particle ratio (FM value) of the hard granulated slag in the furnace front method.

FIG. 2 is a graph showing the relationship between the cooling water temperature during hard granulated slag production and the coarse particle ratio (FM value) of the hard granulated slag in the out-of-furnace method.

FIG. 3 is a graph showing a relationship between a water / slag ratio and a unit volume mass of granulated slag.

FIG. 4 is a graph showing the relationship between the water temperature of the granulated tank and the unit volume mass of the granulated slag.

FIG. 5 is a graph showing a relationship between a cooling water temperature and a coarse particle ratio (FM value) of granulated slag in a pre-furnace method.

FIG. 6 is a side view showing an outline of a granulated slag manufacturing facility of a furnace front type.

FIG. 7 is a side view showing an outline of a granulated slag production facility of an out-of-furnace type.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Blast furnace 2 Tap hole 3 Tap hole 4 Slag gutter 5 Cooling water (: blowing water) injection nozzle 6 blowing box 7 cooling water (: blowing water) 8 Granulation tank 9 Chimney 10 Hot water tank 11 Rotary draining device 11a Cylindrical filter 12 Distributor 13a, 13b Belt conveyor 14 Thermocouple 15 Chilled water tank 16 Cooling tower 17 Weighing device 18a, 18b Product hopper 19 Switching damper 20, 30, Liquid feed pump 21 Flow control valve 22 Cooling water Water) Flow meter 23 Controller 31a Liquid feed pipe 31b Liquid feed bypass pipe 32a, 32b Switching valve 50 Slag pot 51 Melting blast furnace slag 52 Tundish 53 Cold runner 54 Cooling water (blown water) 55 Water injection nozzle 56 Product slag f ₁ molten blast furnace slag in the flow direction f ₂ cooling water: the flow direction of the transport direction f ₄ makeup water flow direction f ₃ granulated slag (吹製water)

Claims (4)

[Claims] 1. A method for producing a coarse-grained hard granulated slag, wherein the molten blast furnace slag is quenched with water to produce hard granulated slag at a cooling water temperature of 60 to 80 ° C. . 2. A method for rapidly cooling a molten blast furnace slag with water to produce hard granulated slag, wherein the temperature of the cooling water is adjusted to be in a range of 60 to 80 ° C. and blown. Method for producing coarse-grained hard granulated slag. 3. The method for producing coarse-grained hard granulated slag according to the present invention is a method for producing granulated slag in a pre-furnace system, wherein a flow rate of cooling water (t-cooling water / hr) / a flow rate of molten blast furnace slag (t- Slag /
The method of claim 1 or 2, wherein the slag is blown under a condition of ≧ 30 and a water temperature in the granulation tank ≦ 95 ° C. 4. The flow rate of the cooling water and the production amount of the granulated slag are measured, and the flow rate of the molten blast furnace slag is obtained from the production amount of the granulated slag, and the cooling water flow rate (t-cooling water / hr) / the molten blast furnace slag flow rate
4. The method for producing coarse-grained hard granulated slag according to claim 3, wherein the slag is blown under the condition of (t-slag / hr) .gtoreq.30.