JP2008045002A - Abrasive, method for manufacturing slag granule and apparatus for manufacturing slag granule - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abrasive excellent in mechanical strength, a method for manufacturing slag granules, and an apparatus for manufacturing slag granules. <P>SOLUTION: The abrasive is composed of slag granules which are amorphous, have an average granule diameter of 5 mm or less, and contains not more than 5% Fe, 25-35% Si, 10-20% Al, 30-40% Ca, and 5-15% Mg. The method for manufacturing slag granules comprises an air granulation step of air granulating molten slag, a cooling step of cooling the air granulated slag by blowing water onto the air granulated slag while allowing it to fall, and a dehydration and carrying step of removing the water used in cooling from the air granulated slag while carrying the same. The apparatus 100 has an air granulation means 110 for air granulating molten slag 200 to form air granulated slag 201, a cooling means 120 to cool the air granulated slag by blowing water onto the same while allowing it to fall, and a dehydration and carrying means 130 to remove the water used in cooling from the air granulated slag while carrying the same. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an abrasive, a method for producing slag grains, and a slag grain producing apparatus. More specifically, the present invention relates to a grinding material using slag grains, a production method for producing slag grains, and a production apparatus for producing slag grains.

Steelmaking slag may be produced in an amount of 10 to 30% by mass of the raw material when refining various metal materials. For this reason, various methods for effectively utilizing steelmaking slag have been studied. Among them, it is considered to use steelmaking slag by making it fine, and it is used as an extender or an abrasive. The following Patent Document 1 is known as an abrasive using slag grains. Moreover, the following patent document 2 is known about the method and its apparatus which manufacture slag grain.
Among these, Patent Document 1 discloses a grinding material on which spinel and forsterite are deposited, and a method for producing the grinding material by blowing it off with air. Patent Document 2 discloses a method and equipment for cooling air-crushed slag while cooling it in a cooler using water as a refrigerant and then collecting it in a collection container.

JP-A-11-58243 JP 2004-238233 A

  In general, when amorphous and crystalline are compared, mechanical strength (such as hardness and crushing strength) is higher in crystalline. For this reason, conventionally, it is considered that the mechanical strength as an abrasive can be obtained by precipitating a crystal phase even in an abrasive manufactured using steelmaking slag or the like. The abrasive disclosed in the above-mentioned Patent Document 1 is obtained by precipitating both crystal phases of spinel and forsterite, and is an abrasive with excellent strength obtained by having crystals. Patent Document 1 does not mention or suggest amorphization. In addition, there is no mention or suggestion of a manufacturing method and a manufacturing apparatus for this purpose.

  In Patent Document 2, a method for obtaining slag grains having high mechanical strength and, therefore, no device contrivance is made, and there is no mention or suggestion. For this reason, it is water-cooled immediately after performing the air crushing, water-cooled for a long time while swirling in the cooler, and further a water-cooling facility may be provided in the recovery container. However, when contacted with water for a long time as described above, and further when contacted with water over a wide temperature range of slag grains, the slag grains become brittle due to excessive cooling and cannot have sufficient mechanical strength. There's a problem.

  This invention is made | formed in view of the above, and aims at providing the grinding material excellent in mechanical strength, the manufacturing method of slag grain, and a slag grain manufacturing apparatus.

  In the process of studying the slag refinement, the present inventors made the slag grains amorphous when subjected to rapid cooling, and initially the mechanical strength was inferior to the crystallized slag grains. Thought. However, it is actually a machine that has a consistent process (means), especially when it is quickly and reliably drained after water cooling, even if it is cooled sufficiently quickly, it does not differ from crystallized slag grains. It was found that slag grains having the desired strength but amorphous were obtained. Furthermore, it has been found that such slag grains can be continuously produced with a highly efficient and compact apparatus. The present invention has been made based on such knowledge.

The present invention is as follows.
(1) It is amorphous and has an average particle size of 5 mm or less,
And Fe is 5 mass% or less in terms of FeO, Si is 25 to 45 mass% in terms of SiO ₂ , Al is 5 to 25 mass% in terms of Al ₂ O ₃ , Ca is 20 to 35 mass% in terms of CaO, and An abrasive comprising slag grains containing 5 to 20% by mass of Mg in terms of MgO.
(2) A method for producing slag grains using steel slag,
A crushing step of crushing the molten steelmaking slag to form a crushed slag;
A cooling step of cooling the air-crushed slag by blowing water while dropping the air-crushed slag.
A dewatering and conveying step of dewatering the water used for the cooling from the air-pulverized slag while conveying the air-pulverized slag.
(3) The said cooling process is a manufacturing method of the slag particle | grains as described in said (2) which is a process of cooling this granulated slag by water discharge, dropping a granulated slag over 3 m or more.
(4) The said slag grain is a manufacturing method of the slag grain as described in said (2) or (3) which is a grinding material as described in said (1).
(5) A slag grain production device for producing slag grains from steelmaking slag,
Wind-pulverizing means for air-melting molten steelmaking slag to form air-pulverized slag,
Cooling means for cooling the air-crushed slag by spraying water while dropping the air-crushed slag downward;
Dewatering and conveying means for dewatering the water used for cooling from the air-pulverized slag while conveying the air-pulverized slag, and a slag grain manufacturing apparatus.
(6) The slag particle manufacturing apparatus according to (5), wherein the air crushing means includes a ring nozzle having a plurality of nozzles arranged radially so that gas can be discharged toward the center.
(7) The cooling means includes a chamber having an internal space in which the crushed slag is dropped over 3 m,
The slag grain manufacturing apparatus according to (5) or (6), further comprising: a water discharge unit that discharges water toward the wind-crushed slag falling in the chamber.
(8) The dehydrating and conveying unit according to any one of (5) to (7), wherein at least a part of the dewatering and conveying unit includes a wedge wire screen including wedge wires arranged at intervals at which the air-pulverized slag is not passed. Slag grain production equipment.
(9) comprising vibration generating means for transmitting the generated vibration to the wedge wire screen;
The slag grain manufacturing apparatus according to any one of (5) to (8), wherein the wedge wire screen conveys the crushed slag while performing the dehydration by vibration.
(10) The slag particle manufacturing apparatus according to any one of (5) to (9), wherein the slag particle is the abrasive according to (1).

  According to the abrasive of the present invention, since it has excellent mechanical strength, particularly hardness and crushing strength, it is greatly suppressed that the abrasive is pulverized by an impact during the grinding process. For this reason, it can be used repeatedly and is excellent in recyclability.

According to the method for producing slag particles of the present invention, slag particles having excellent mechanical strength can be produced. In particular, it can be manufactured continuously, and in a small space.
When having a cooling process that cools down by dropping water while dropping the crushed slag, it is not necessary to use a large space in the plane direction, and slag grains with excellent mechanical strength can be stably produced in a small space. .
When the slag grain is an abrasive, it can be produced continuously, can be produced in a small space, and an abrasive having excellent mechanical strength can be stably obtained.

According to the slag particle manufacturing apparatus of the present invention, slag particles having excellent mechanical strength can be manufactured. In particular, it can be manufactured continuously, and the device can be stored in a small space.
When the air crushing means has a ring nozzle, slag grains having a stable shape can be produced more efficiently. Moreover, it is possible to stably obtain slag grains having a more spherical shape and excellent mechanical strength.
In the case where the cooling means includes a chamber having an internal space in which the crushed slag is dropped and a water discharge means for discharging water toward the crushed slag falling downward in the chamber, appropriate cooling can be performed even in a small space. It can be carried out. For this reason, the slag grain which is excellent in mechanical strength with high efficiency can be manufactured.
When at least a part of the dewatering and conveying means is a wedge wire screen, slag grains can be continuously produced. In addition, slag grains having excellent mechanical strength can be stably produced by preventing supercooling while efficiently performing dehydration and heat removal.
When the vibration generating means is provided, dehydration and heat removal are performed more efficiently, and slag grains having the above-described excellent characteristics can be manufactured more stably.
When the slag grain is an abrasive, it can be produced continuously, can be produced in a small space, and an abrasive having excellent mechanical strength can be stably obtained.

The present invention will be described in detail below.
[1] Abrasive Material The abrasive material of the present invention is amorphous, has an average particle size of 5 mm or less, Fe is 5 mass% or less in terms of FeO, and Si is 25 to 45 mass% in terms of SiO _2. It is characterized by comprising slag grains containing 5 to 25% by mass of Al in terms of Al ₂ O ₃ , 20 to 35% by mass of Ca in terms of CaO, and 5 to 20% by mass of Mg in terms of MgO.

The term “amorphous” means that no crystal peak is observed by X-ray diffraction measurement both on the surface and inside. That is, a halo figure peculiar to amorphous is recognized in the chart obtained by X-ray diffraction measurement.
The “average particle size” is 5 mm or less. When the average particle size exceeds 5 mm, it is not usually used as an abrasive. The average particle diameter is preferably 0.05 to 4.0 mm, more preferably 0.1 to 3.0 mm, and particularly preferably 0.2 to 2.0 mm.

The Fe is 5% by mass or less (preferably 0.1 to 2% by mass) in terms of FeO. If it exceeds 5% by mass, the hardness of the obtained slag particles tends to decrease, which is not preferable. The Si is 25 to 45 mass% in terms of SiO ₂ (preferably 28 to 40% by weight). If it is less than 25% by mass or exceeds 45% by mass, the viscosity of the molten slag (winded slag) tends to increase and become fibrous at the time of winding. The Al is 5 to 25 mass% in terms _{of Al} 2 _{O 3} (preferably 8-15 wt%). If it is less than 5% by mass or exceeds 25% by mass, the hardness of the slag particles obtained is lowered, and the melting point of the slag tends to be excessively high, which is not preferable. Ca is 20 to 35% by mass (preferably 30 to 32% by mass) in terms of CaO. If it is less than 20% by mass or exceeds 35% by mass, the viscosity of the molten slag (winded slag) tends to increase to become fibrous during the pulverization, and the melting point of the slag tends to become excessively high. Mg is 5 to 20% by mass (preferably 10 to 13% by mass) in terms of MgO. If it is less than 5% by mass or exceeds 20% by mass, the melting point of the slag tends to be excessively high, which is not preferable. In particular, this abrasive contains a relatively large amount of Ca (usually containing CaO). For this reason, it is thought that it can be set as the grinding material of high intensity | strength and high hardness.

The Vickers hardness of the slag grains constituting the abrasive of the present invention can be 650 Hv or more (particularly 680 to 900 Hv, more preferably 700 to 850 Hv).
Furthermore, the crushing strength of one slag grain constituting the abrasive can be 20 kg or more (particularly 30 to 70 kg, more preferably 45 to 60 kg).

[2] Slag Grain Production Method The slag grain production method of the present invention is a slag grain production method using molten steelmaking slag (hereinafter, also simply referred to as “molten slag”), and the molten steelmaking A wind-crushing step of air-pulverizing slag to form air-crushed slag, a cooling step of cooling the air-crushed slag by blowing water while dropping the air-crushed wind-crushed slag, A dehydration conveyance step of dewatering the water used for the cooling from the air-crushed slag while conveying the crushed slag.

  The “wind crushing step” is a step of crushing molten slag to form a wind slag. Crushing refers to pulverization using gas, and is usually performed by supplying molten slag before the gas discharged from the nozzle. The shape and number of nozzles used at this time are not particularly limited. That is, for example, a ring nozzle having a plurality of nozzles arranged radially so that gas is emitted toward the center, and a plurality of nozzles arranged so as to face each other so that gas is emitted toward the center. A parallel nozzle having Among these, the ring nozzle is preferable. The ring nozzle can be provided with a uniform arrangement of nozzles radially around the entire circumference, and is effective for obtaining slag particles having uniform and excellent mechanical strength, which can more uniformly refine the molten slag.

The number of nozzles (gas discharge ports) provided in the ring nozzle is not particularly limited, but is usually 20 to 100, preferably 20 to 70, and more preferably 30 to 60. In this range, more stable air crushing can be performed.
Also, the angle α (see FIG. 2) with respect to the center of each nozzle is not particularly limited, but is usually an angle of 5 to 45 degrees with respect to the falling direction of the molten slag (usually perpendicular to the ground). 15 to 35 degrees are preferable, and 20 to 30 degrees are more preferable. If it is this range, it will be easy to crush molten slag. Moreover, the upward splashing of the crushed slag particles can be prevented, and the slag particles still in a high temperature state can be easily prevented from sticking to each other.

Furthermore, although the gas discharge pressure from a nozzle is not specifically limited, Usually, it is 3-25 kgf / cm < ² > per nozzle, 5-23 kgf / cm < ² > is preferable and 7-20 kgf / cm < ² > is more preferable. In this range, it is particularly easy to form small-diameter slag particles, and it is possible to suppress the collapse of the shape of the slag particles obtained when the air-pulverized slag collides with the chamber inner wall or the like.
Further, the amount of the gas released is not particularly limited, but it is preferable that the amount of the crushed slag to be dropped is appropriate depending on the particle size and the like. For example, the molten slag amount is 2000 to 4000 kg per 60 minutes (more (2500 to 3000 kg), the gas release amount is preferably 600 to 6000 kiloliters (more preferably 800 to 4000 kiloliters, more preferably 1250 to 3500 kiloliters) per 60 minutes. Moreover, the kind of said gas used for crushing is not specifically limited, Although various gas can be used, In order to make an apparatus a simple structure, it is preferable to use air.

  Moreover, although the temperature of the molten slag to be used is not particularly limited, the slag used in the present invention is preferably 1150 to 1600 ° C. (more preferably 1200 to 1550 ° C., more preferably 1300 to 1500 ° C.). Furthermore, any steelmaking slag may be used. For example, slag obtained when metals are melted in various furnaces is included. The furnace may be any furnace, and includes an electric furnace and a melting furnace. Furthermore, the metal may be any metal, including scrap metal and ore. That is, for example, scrap melting slag, stainless steel refining slag, alloy steel refining slag, special steel refining slag, and general steel refining slag that are generated when scrap metal is melted. Among these, when using the obtained slag grains as an abrasive, stainless steel refining slag and scrap melting slag are preferable. This is because slag grains obtained from stainless steel smelting slag have both particularly excellent hardness and excellent crushing strength.

  The “cooling step” is a step of cooling the air-crushed slag by blowing water while dropping the air-crushed air-crushed slag. By carrying out this cooling step, the crushed slag can be appropriately cooled. That is, normally, according to this cooling process, even if the outer surface part of the air-pulverized slag is cooled, the air-pulverized slag can be sent to the dehydrating and conveying process without being cooled to the core part. That is, usually, the thermal conductivity of the slag used in the present invention is about 0.3 to 2 W / (m · K). Therefore, the air-cooled slag is not collapsed due to excessive cooling, and an excessively long cooling process or a reheating process is required, resulting in a complicated manufacturing method and an increase in the size of the apparatus. No.

  As a cooling method generally performed in the cooling step, water cooling, air cooling, or the like can be considered. The method of the present invention uses water cooling. In the production of slag grains, sufficient cooling efficiency cannot be obtained only by air cooling (natural heat dissipation, gas blowing, etc.), and a large space (especially a large area and a long cooling distance) is required for heat removal. However, in the method of the present invention, a sufficient cooling effect can be obtained in a small space.

In addition, when water cooling is performed, besides the cooling method in the present invention, a method of dropping the crushed slag into the water stored in the chamber is conceivable as a method for saving space. However, in this method, the air-crushed slag is collapsed due to excessively rapid cooling (deformed and cracked easily). On the other hand, in the method of the present invention, appropriate cooling can be performed and the crushed slag is not collapsed. Furthermore, since it does not pass through water and falls in the gas vertically downward, the shape of the crushed slag can be formed into a shape closer to a spherical shape. Therefore, it is easy to maintain a shape that can exhibit high mechanical strength.
Furthermore, in the method of dropping the crushed slag into water, it is necessary to close the lower end of the chamber in order to store the water in the chamber, and the production of slag particles is performed in a batch manner. On the other hand, in the method of this invention, it can be used in the state which opened the chamber, can manufacture a slag grain continuously, and can exhibit high manufacturing efficiency. Particularly in a steelmaking facility that is continuously operated, there is an advantage that the cost of storing slag before pulverization can be reduced.

Although the drop distance at the time of performing the said cooling process is not specifically limited, Usually, it is 3 m or more (preferably 4-10 m, More preferably, 4.5-8 m, Especially preferably, 5-7 m, Usually 40 m or less). If the fall distance is within this range, cooling can be performed in a small space while preventing insufficient cooling. Therefore, it is possible to efficiently produce slag grains having excellent mechanical strength while keeping the apparatus compact.
Further, the amount of water spray is not particularly limited, but usually 0.8 liter or more of water (preferably 0.3 to 1.2 liters, more preferably 0.5 to liters) per 1 kg of crushed slag particles. 1.0 liter) is preferred.
Also, the direction of water spray is not particularly limited, and it may be sprayed from the side in the vertical direction with respect to the fallen crushed slag, or may be blown horizontally from above to the fallen crushed slag. Well, it may be sprayed horizontally from below to the top of the crushed slag. Among these, it is preferable to spray from the side and from below to above. This is because, by using the counter flow, an excellent cooling effect can be obtained, and the time during which the pulverized slag stays in the chamber can be increased.

  The “dehydration transport process” is a process of removing water adhering in the cooling process from the air-pulverized slag while transporting the air-pulverized slag that has passed through the cooling process. By this dewatering and conveying step, water is removed from the pulverized slag (whether or not it is completely removed), and heat is further dissipated. In this dewatering and conveying step, the crushed slag sent from the cooling step usually has sufficient heat to vaporize the water, so that part of the dehydrated water is removed by vaporization. It will be. For this reason, it is thought that a part of the heat of the air-pulverized slag is removed by the heat of vaporization of water in the dehydration conveyance process. That is, the temperature of the pulverized slag sent from the cooling step to the dehydrating and conveying step is not particularly limited, but it is usually considered to be preferably 800 ° C. or higher (preferably 800 to 1200 ° C.).

  Further, the temperature of the slag grains recovered after passing through the dewatering and conveying step is 70 ° C. or more (more preferably 80 to 800 ° C., further preferably 85 to 500 ° C., particularly preferably 90 to 200 ° C., particularly 100 to 150 ° C. ) Is preferable. In this range, the obtained slag grains can be kept amorphous, and slag grains having particularly excellent mechanical strength can be obtained. The transport time in this dehydration transport process, that is, the heat release time is not particularly limited, but is usually 0.5 to 10 minutes (preferably 0.5 to 3 minutes, more preferably 1 to 2 minutes). In this range, slag grains having particularly excellent mechanical strength can be obtained.

In the manufacturing method of the slag particle | grains of this invention, other processes can be provided besides said crushing process, cooling process, and dehydration conveyance process. Examples of other steps include a grinding step and a fractionation step.
The said grinding process (granulation process) is a process of rubbing the air-pulverized slag obtained through the dehydration conveyance process. By performing this milling step, it is possible to form a deformed and crushed slag formed by connecting a plurality of crushed slags before being sufficiently cooled into a more spherical shape. That is, it can be divided into particles from the connecting portion of the irregularly shaped crushed slag and formed into a normal particle shape. For example, the shape of the slag particles of the finished product can be made closer to a spherical shape by grinding needle-shaped, whisker-shaped, and slender shaped crushed slag.
The fractionation step is a step that can be provided after the dehydration conveyance step and, after the grinding step, if it is provided with the grinding step, of the desired shape and / or particle size from the obtained slag particles. This is a step of separating slag grains. In this step, it is usually separated using a sieve.

[3] Slag Grain Production Device The slag grain production device of the present invention is a method of crushing molten steel-making slag to form a crushed slag, and spraying water while dropping the crushed slag. And cooling means for cooling the crushed slag, and dehydrating and conveying means for dewatering the water used for the cooling from the crushed slag while conveying the crushed slag.

  The “wind-crushing means” is means for crushing the molten slag to form the air-crushed slag. This air crushing is performed using the gas discharged from the nozzle. The shape and number of nozzles used for air crushing are not particularly limited. That is, for example, a ring nozzle having a plurality of nozzles arranged radially so that gas is emitted toward the center, and a plurality of nozzles arranged so as to face each other so that gas is emitted toward the center. A parallel nozzle having Among these, the ring nozzle is preferable. About this ring nozzle, the ring nozzle in the manufacturing method of the said slag grain can be applied as it is. Further, the arrangement position of the ring nozzle is not particularly limited, but it is preferable to arrange the ring nozzle at the upper end of the chamber described later in order to save space.

  The “cooling means” is a means for cooling the air-crushed slag by blowing water while dropping the air-crushed slag. Therefore, the chamber is usually provided with a chamber for dropping the crushed slag and a water discharge means for blowing water onto the crushed slag. By providing the chamber, the crushed slag can be dropped without being affected by the surrounding environment. Furthermore, the cooling effect by the water discharge means is also improved.

  The shape of the chamber is not particularly limited, but is usually a vertically long shape. Due to the vertically long shape, it is possible to save space while ensuring a drop distance. As described above, this drop distance is usually 3 m or more (preferably 4 to 10 m, more preferably 4.5 to 8 m, particularly preferably 5 to 7 m, usually 40 m or less). Therefore, the space in the chamber also usually has this distance in the vertical direction. The shape in the lateral direction (the cross-sectional shape in the falling direction of the crushed slag) is not particularly limited, and may be circular, rectangular, or other shapes, but may be circular. preferable. It is because it is excellent in the collection | recovery efficiency of a crushed slag. For example, when it is circular (in the case of not being circular, the maximum internal length), the inner diameter of the main part is preferably 1 to 10 m (more preferably 2 to 8 m, still more preferably 3 to 6 m). Further, it is preferable that the lower end of the chamber has a tapered portion that is tapered toward the dehydrating and conveying means. Further, as described above, it is preferable that the lower end of the chamber is open to the dehydrating and conveying means. Thereby, a slag grain can be manufactured by a continuous type and the mechanical strength of the obtained slag grain can be kept high.

  The water discharge means only needs to be able to discharge water to the pulverized slag, and the form and size thereof are not particularly limited, but the water discharge by the water discharge means is performed when the above-mentioned wind crushing means (for example, a ring nozzle is used). Is preferably performed within a range of 1 to 10 m (more preferably 1.5 to 7 m, still more preferably 2 to 5 m) from the tip of the ring nozzle. On the other hand, it is preferable that this water discharge is performed in a range where the distance to the dehydrating and conveying means is 1 to 10 m (more preferably 1.2 to 5 m, still more preferably 1.3 to 3 m). If it is provided too close to the air crushing means, it is not preferable because the air crushing slag surface is excessively cooled before being solidified, and it is not preferable. This is because it is difficult to obtain a sufficient cooling effect. Furthermore, although the water discharge angle at the time of performing water discharge is not specifically limited, it discharges in the angle range of 20-180 degree | times (more preferably 60-180 degree | times, still more preferably 90-180 degree | times) with respect to the falling direction of a crushed slag. It is preferable to be arranged as described above.

  The “dehydrating and conveying means” is means for dewatering water used for cooling from the air-pulverized slag while conveying the air-pulverized slag. Since the dewatering and conveying means has both the dehydrating function and the conveying function, slag grains can be continuously produced. That is, after the air-crushed slag is dropped and cooled by spraying water, the crushed slag does not stay in the cavity in a wet state, and is subsequently dewatered. Be transported. For this reason, the pulverized slag is not excessively rapidly cooled, and slag grains having excellent mechanical strength can be obtained. Furthermore, such slag grains can be continuously produced stably and efficiently.

  Further, the dehydrating function and the conveying function in the dehydrating and conveying means may be provided over the entire dehydrating and conveying means (that is, for example, when the whole consists of a wedge wire screen), only a part has both functions, The other part may have only a transport function (that is, for example, when the front part is made of a wedge wire screen and the rear part is made of a heat-resistant conveyor such as a steel conveyor). This is because, even in the latter case, even with a dehydrating and conveying means having only a conveying function at the rear part, water can be evaporated by the heat that the crushed slag has at this stage while being radiated. Usually, in this dewatering and conveying means, compared to the case where the crushed slag has already been cooled to such an extent that water cannot be evaporated by the heat it has at this stage (for example, less than 70 ° C.). When the temperature is maintained so that water can be evaporated (for example, 80 ° C. or higher, preferably 100 ° C. or higher), slag grains having higher mechanical strength tend to be obtained.

In this dewatering and conveying means, it is preferable that the temperature of 800 ° C. or higher is maintained in the crushed slag immediately after being transferred from the cooling means. Further, in this dehydrating and conveying means, cooling is performed at a rate of 130 to 600 ° C./min (more preferably 150 to 400 ° C./min, more preferably 180 to 300 ° C./min, particularly preferably 180 to 250 ° C./min) (usually ). In this range, a shorter transport distance can be achieved while performing sufficient dehydration and cooling, and product quality and space saving can be achieved particularly effectively.
In addition, as described above, when the dehydrating and conveying means does not have a dehydrating function in the latter half portion but has a conveying part having a conveying function, the conveying part may convey the crushed slag in the plane direction. It can be conveyed in the vertical direction. That is, for example, a bucket conveyor or the like can be mentioned. Thereby, further space saving can be achieved.

The form of the dewatering and conveying means is not particularly limited, but the dewatering and conveying means preferably includes a wedge wire screen including wedge wires arranged at intervals at which the air-pulverized slag does not pass as at least a part of the dewatering and conveying means. Furthermore, when the wedge wire screen is provided only in a part, it is preferable that the wedge wire screen is provided on the leading end side (side closer to the cooling means) in the dewatering and conveying means. This is because the wedge wire screen can be dehydrated and transported with simple equipment.
Although the form of the wedge wire used for this wedge wire screen is not particularly limited, it is 0.1 to 4.0 mm (preferably 0.1 to 1.0 mm) when the target slag grains have an average particle size of 5 mm or less. It is preferable to use a wedge wire having a screen interval of 0 mm, more preferably 0.2 to 0.5 mm. This is because it is easier to obtain slag grains that are closer to a spherical shape without performing a grinding process (a sizing process) in a subsequent process.

  When the wedge wire screen is used, it is preferable that the wedge wire screen can perform dehydration by vibration. Moreover, it is preferable that the pulverized slag can be conveyed simultaneously by this vibration. Therefore, it is preferable that the dehydrating and conveying means includes a vibration generating means that can transmit the generated vibration to the wedge screen.

  The slag particle production apparatus of the present invention can include other means besides the air crushing means, the cooling means, and the dehydrating and conveying means. As other means, there is a molten slag storing means for sending an appropriate amount of molten slag to the air crushing means. The molten slag storage means can further include heating means such as a burner and / or a heater in order to prevent the stored molten slag from being allowed to cool. As the molten slag storing means, a tundish is usually used. The capacity and shape of the tundish are not particularly limited, but it is preferable to provide an opening that allows the molten slag to flow downward. Further, the opening is preferably circular and has an inner diameter of 10 to 50 mm (more preferably 12 to 30 mm, still more preferably 14 to 24). Further, the depth of the tundish is preferably 50 to 200 cm (more preferably 70 to 150 cm, still more preferably 80 to 120 cm). Furthermore, the outflow rate of the molten slag from the tundish is preferably 5 to 40 liters / minute (more preferably 10 to 30 liters / minute, still more preferably 15 to 20 liters / minute).

  As another means, the cooling means is provided with the chamber, and the lower end thereof has a tapered shape toward the dehydrating and conveying means as described above (that is, has a tapered shape portion). In this case, in order to prevent the water-cooled slag particles from staying in the tapered shape portion, water can be formed along the inner wall surface of the tapered shape portion in addition to the water discharge means provided in the cooling means. It is possible to provide a stagnation water discharge means that can flow down. The form and the like of the stay prevention water discharge means are not limited. For example, a stay water discharge means may be formed by arranging a water discharge pipe in a ring shape above the tapered portion of the chamber (may be just above). it can.

  Furthermore, as another means, a water discharge means at the time of carrying out water discharge for further cooling the crushed slag carried by the dewatering and conveying means can be provided. Although the form etc. of the water discharge means at the time of conveyance are not limited, For example, a water discharge pipe can be arrange | positioned in parallel with a dehydration conveyance means (for example, wedge wire screen).

  Further, as other means, a heat exchange means can be provided. The heat exchanging means is means for recovering heat released in the slag grain production apparatus in the process where the molten slag becomes the air-pulverized slag. Although the form etc. of a heat recovery means are not limited, It can be set as a heat recovery means by providing well-known various heat recovery devices in various places (for example, a chamber part, a tundish part, etc.) of a slag grain manufacturing apparatus. By providing the heat recovery means, the exhaust heat can be used efficiently and the cooling efficiency can be improved.

  Furthermore, as other means, a grinding means for performing the grinding step in the production method can be provided. Equipment such as an Eirich mixer and a mortar mixer can be used as the grinding means. Furthermore, after this grinding means, a separating means for performing the manufacturing method can be provided. As the sorting means, a sieve device such as a vibration sieve and a monolayer can be used.

Hereinafter, the present invention will be specifically described by way of examples.
[1] Slag Grain Production Apparatus The slag grain production apparatus shown in FIG. 1 was manufactured using the slag grain production apparatus having the structure near the wind crushing means shown in FIG.
The slag grain manufacturing apparatus 100 shown in FIG. 1 includes a wind crushing unit 110, a cooling unit 120, a dewatering conveyance unit 130, and a collection container 140. Furthermore, a molten slag storage means (tundish) 150 is provided as a pre-means for the air crushing means 110. Further, almost all of this slag grain manufacturing apparatus is disposed in the underground pit (external leakage of operating noise can be suppressed by the underground arrangement).

The molten slag storage means 150 is a so-called tundish. The tundish 150 has a rectangular parallelepiped shape of 200 cm × 100 cm × 100 cm deep, and an opening 151 having a diameter of about 18 cm is provided at the bottom so that molten slag can be supplied to the air crushing means. Furthermore, the burner 152 which can adjust the temperature of the molten slag stored in the tundish 150 is provided. In addition, a dam and a damper (not shown) are also provided to prevent inflow of massive foreign matter.
The air crushing means (ring nozzle) 110 is composed of a ring nozzle (total diameter 30 cm) in which 45 nozzles 111 are arranged radially toward the central portion. The angle α (see FIG. 2) of each nozzle is set to 26 to 27 degrees.

  The cooling means 120 includes a chamber 121, a water discharge means 126, and a stay prevention water discharge means 128. Among these, the chamber 121 is a cylinder having a cylindrical portion 122 having a diameter of 400 cm and a length of 4.3 m, and a tapered portion 123 extending from the cylindrical portion 122 and having a lower end diameter of 150 cm and a length of 1.4 m. The shape (the falling distance of the crushed slag immediately after the pulverizing means is 5.7 m). The water discharge means 126 includes a water discharge nozzle 127. The water discharge nozzle 127 is disposed so that the water discharge nozzle is exposed in the chamber from the middle of the cylindrical portion 122 of the chamber 121 (position 2 to 3.5 m from the upper end of the chamber). In addition, twelve water discharge nozzles are arranged radially toward the center of the chamber 121. Furthermore, the stay prevention water discharge means 128 includes a water discharge nozzle 129. The water discharge nozzle 129 is disposed so that the water discharge nozzle is exposed in the chamber from the vicinity of the upper end of the tapered portion 123 of the chamber 121 so that water can flow down along the inner wall.

  The dewatering and conveying means 130 includes a wedge wire screen 132 having a length of 3 m in which inverted triangular wedge wires 131 are arranged with a gap of 0.2 mm, and a bucket conveyor 134 having a length of 12.5 m in the vertical direction. . Among these, the wedge wire screen 132 is connected to the vibration generator 133 and vibrates at a vibration (vertical direction) width of 6 mm and about 60 Hz. On the wedge wire screen 132, the crushed slag 201 dropped through the cooling means by the vibration is transported while being dehydrated at a transport speed of about 12 m / min. On the other hand, the bucket conveyor 134 is a conveyor that carries the crushed slag 201 conveyed from the wedge wire screen 132 from the underground pit to the collection container 140 disposed on the ground, and has a conveying length of 9 m in the vertical direction. .

[2] Production of slag grains (1) Example 1
Using the slag grain production apparatus of [1] above, slag grains were produced as follows using steelmaking slag obtained in a stainless steel furnace as a slag grain raw material.
About 3 tons of as-melted steelmaking slag (molten slag) 200 obtained in a stainless steel furnace was charged into the tundish 150 of the slag grain production apparatus of [1].

The molten slag 200 was supplied from the opening at the bottom of the tundish 150 into the chamber 121 and then passed through the center of the ring nozzle 110. Air was discharged from the ring nozzle 110 at a gas discharge pressure of 16 kgf / cm ² . As a result, the molten slag 200 passing through the ring nozzle 110 became a particle shape by air crushing and dropped in the chamber 121. In the chamber 121, water was discharged from the water discharge means 126 at a water discharge pressure of about 40 liters / minute and about 0.3 to 0.4 MPa to cool the crushed slag 201.
Further, the water is washed out by the water discharged from the stay prevention water discharge means 128 disposed on the inner wall of the tapered portion 123 of the chamber 121, and is discharged from the tapered portion 123, on the wedge wire screen 132 of the dewatering and conveying means 130. Was fallen into. In this stay prevention water discharge means 128, water was discharged at a water discharge pressure of 30 liters / minute and about 0.3 to 0.4 MPa.

On the wedge wire screen 132, the crushed slag 201 was dropped and dehydrated, and the crushed slag 201 was sequentially sent to the bucket conveyor 134 by vibration. The crushed slag 201 immediately after being dropped on the wedge wire screen 132 was visually observed in a black-red state, and was observed to have a temperature of around 1000 ° C. The conveyance time on the 3 m long wedge wire screen was 0.25 minutes, and was further conveyed by the bucket conveyor 134 at a speed of 8 m / min and collected in the collection container 140. Moreover, the temperature of the crushed slag immediately after being accommodated in this collection container was 99.5 degreeC.
After that, the crushed slag 201 was recovered from the collection container 140, put into a separate grinding device, and ground for 2 minutes under the conditions of an agitator rotation speed of 800 rpm and a bread rotation speed of 85 rpm. Next, the slag particles obtained by passing through a 0.2 mm sieve were collected.

(2) Example 2
Slag particles were produced in the same manner as in Example 1 above. As a result, the temperature of the crushed slag immediately after being accommodated in the collection container 140 was 99.6 ° C. Then, the slag grain was obtained by performing the grinding process and the fractionation process similarly.

(3) Evaluation of slag grains In Examples 1 and 2, the slag grains obtained were measured for average particle diameter using a low-rop shaker screen. As a result, the average particle diameter of both the slag grains of Example 1 and Example 2 was 0.9 mm.

  Moreover, the measurement of Vickers hardness was performed with respect to five arbitrarily selected slag grains using a Vickers hardness meter (manufactured by Akashi Seisakusho Co., Ltd., type “MVK”). As a result, the average value of the Vickers hardness of the slag grains of Example 1 was 750 Hv, and the average value of the Vickers hardness of the slag grains of Example 2 was 780 Hv.

  Furthermore, the crushing strength was measured with respect to five arbitrarily selected slag grains using a crushing strength measuring meter (manufactured by Tokyo Henki Seisakusho, model “Amsler type universal material testing machine AU-30”). As a result, the average value of the crushing strength of the slag grains of Example 1 was 47 kg / piece, and the average value of the crushing strength of the slag grains of Example 2 was 49 kg / piece.

Moreover, about the slag particle | grains of Example 1, the X-ray-diffraction measurement (CuK (alpha) ray) of both a surface part and an inside was performed. The measurement of the surface part was performed in the form of particles, and the internal measurement was performed by pulverizing only the inside of the crushed slag grains and measuring the powdery body. The results are shown in FIG. 3 (front portion) and FIG. 4 (inside). In both FIG. 3 and FIG. 4, the chart shown in the lower stage is the data of Experimental Example 1. As a result, no crystal phase was observed in any of the measurements (note that the marks such as ●, ▲, and ■ in FIGS. 3 and 4 indicate the positions where these crystal phases should appear. Is not a sign indicating that
Moreover, as a reference example, it is the same about the grinding material (Product name "Wind Dream JF-2000", particle size range 0.2-2.0mm, Vickers hardness 791-813Hv) made from the molten slag by Nippon Heavy Chemical Industry Co., Ltd. The measured X-ray diffraction measurement was performed. The results are shown in multiple charts in FIGS. The chart shown in the upper part of each figure is a reference example.

Furthermore, composition analysis was performed on the slag grains of Example 1 and Example 2. As a result, the slag grains Example 1, 0.5 mass% of Fe in FeO terms, 35% by mass of Si in terms of SiO _2, 12 wt% of Al in terms _{of Al} 2 _{O 3,} the Ca in terms of CaO 28 It contained 12 mass% in terms of MgO in terms of mass% and MgO. Likewise, the slag grains Example 2, 1.0 mass% of Fe in FeO terms, 31% by mass of Si in terms of SiO _2, 11 wt% of Al in terms _{of Al} 2 _{O 3,} the Ca in terms of CaO 26 It contained 11 mass% in terms of MgO in terms of mass% and MgO.

  From these results, it can be seen that the obtained slag grains have excellent mechanical strength even though they are amorphous. Moreover, it turns out that it has the mechanical strength which can be utilized as an abrasive from this result. Moreover, according to the manufacturing method of this invention, it turns out that these slag grains which have the outstanding mechanical strength can be manufactured stably. Similarly, according to the manufacturing apparatus of this invention, it turns out that these slag grains which have the outstanding mechanical strength can be manufactured stably.

It is explanatory drawing which shows typically an example of the slag grain manufacturing apparatus of this invention. It is explanatory drawing which shows typically the vicinity of the crushing means in the slag grain manufacturing apparatus of this invention. It is explanatory drawing using the X-ray-diffraction measurement result of the surface part of the slag grain concerning an Example. It is explanatory drawing using the X-ray-diffraction measurement result inside the slag grain concerning an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100; Slag grain manufacturing apparatus, 110; Crushing means (ring nozzle), 111; Nozzle, 120; Cooling means, 121; Chamber, 122; Cylindrical part, 123; Nozzle, 128; Water retention prevention means, 129; Water discharge nozzle, 130; Dewatering and conveying means, 131; Wedge wire, 132; Wedge wire screen, 133; Vibration generator, 134; Bucket conveyor, 140; Collection container, 150; Slag storage means (tundish), 151; opening of molten slag storage means, 152; burner, 200; molten slag, 201; slag grains (wind-crushed slag, abrasive).

Claims (10)

Is amorphous and has an average particle size of 5 mm or less,
And Fe is 5 mass% or less in terms of FeO, Si is 25 to 45 mass% in terms of SiO ₂ , Al is 5 to 25 mass% in terms of Al ₂ O ₃ , Ca is 20 to 35 mass% in terms of CaO, and An abrasive comprising slag grains containing 5 to 20% by mass of Mg in terms of MgO. A method for producing slag grains using steel slag,
A crushing step of crushing the molten steelmaking slag to form a crushed slag;
A cooling step of cooling the air-crushed slag by blowing water while dropping the air-crushed slag.
A dewatering and conveying step of dewatering the water used for the cooling from the air-pulverized slag while conveying the air-pulverized slag.   The method for producing slag particles according to claim 2, wherein the cooling step is a step of cooling the crushed slag by water discharge while dropping the crushed slag over 3 m or more.   The said slag grain is a grinding material of Claim 1, The manufacturing method of the slag grain of Claim 2 or 3. A slag grain production device for producing slag grains from steelmaking slag,
Wind-pulverizing means for air-melting molten steelmaking slag to form air-pulverized slag,
Cooling means for cooling the air-crushed slag by spraying water while dropping the air-crushed slag downward;
Dewatering and conveying means for dewatering the water used for cooling from the air-pulverized slag while conveying the air-pulverized slag, and a slag grain manufacturing apparatus.   The slag grain manufacturing apparatus according to claim 5, wherein the air crushing means includes a ring nozzle having a plurality of nozzles arranged radially so that gas can be discharged toward the center. The cooling means includes a chamber having an internal space in which the crushed slag is dropped over 3 m,
The slag grain manufacturing apparatus of Claim 5 or 6 provided with the water discharge means which discharges water toward this wind-crushed slag falling in this chamber.   The slag grain manufacturing apparatus according to any one of claims 5 to 7, wherein the dewatering / conveying means includes a wedge wire screen including at least a portion of wedge wires arranged at intervals at which the air-pulverized slag is not passed. Comprising vibration generating means for transmitting the generated vibration to the wedge wire screen;
The slag grain manufacturing apparatus according to any one of claims 5 to 8, wherein the wedge wire screen conveys the crushed slag while performing the dehydration by vibration.   The slag grain manufacturing apparatus according to any one of claims 5 to 9, wherein the slag grain is the abrasive according to claim 1.

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