JPH0313181B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing cement that utilizes blast furnace slag as an auxiliary raw material for cement.

As is well known, molten blast furnace slag at a temperature of approximately 1400°C is discharged from a steelmaking blast furnace during its operation.
This blast furnace molten slag has conventionally been used in various fields as slowly cooled slag, rapidly cooled slag, etc., for example, as an auxiliary material for cement production, but when the sensible heat is recovered, it is used in some cases for power generation, etc. Currently, it is not being utilized effectively enough.

The present invention was made in view of the above circumstances, and
By bringing the steelmaking blast furnace and cement manufacturing equipment closer together,
The object of the present invention is to provide a method and apparatus for producing cement that can effectively utilize the thermal energy of molten slag in a steelmaking blast furnace.

The method for manufacturing cement using blast furnace molten slag of the present invention includes guiding the blast furnace molten slag discharged from a steelmaking blast furnace to cement manufacturing equipment through a molten slag transfer path, and transferring the blast furnace molten slag to a preheating step of the cement manufacturing equipment. In the calcination or firing process,
The molten slag is quantitatively sprayed onto cement raw materials (consisting of limestone, clay, etc.) and mixed with the cement raw materials, and the sensible heat of the molten slag is imparted to the cement raw materials to provide preheating heat in the cement manufacturing process. , it is characterized in that it is effectively used as part of the heat for calcination or the heat for firing.

In addition, the cement manufacturing apparatus of the present invention has a structure in which there is a
A molten slag transfer path is provided, and at one end of the molten slag transfer path, a cement raw material is introduced into the preheater, calcination furnace, or sintering furnace of the cement manufacturing equipment, or into the preheater, calcination furnace, or sintering furnace. A spraying device for quantitatively spraying the molten slag is installed inside the duct, and the cement raw material and molten slag are mixed and the sensible heat of the molten slag is used as heat for preheating, heat for calcination, or heat for firing. The feature is that the heat is effectively used as part of the heat.

Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the cement manufacturing apparatus of the present invention. In this figure, numeral 1 is a steelmaking blast furnace, and 2 is a cement manufacturing facility.

First, to explain the general configuration, the blast furnace 1 is one in which blast furnace molten slag is periodically discharged during normal operation, and is provided with a molten slag discharge port 1a at its lower part. The cement manufacturing equipment 2 has a well-known configuration including cyclone preheaters 3a to 3c, a separation cyclone 4, a calciner 5, a rotary kiln 6, and the like. A molten slag transfer path 8 is provided between the discharge port 1a of the blast furnace 1 and the kiln bottom 6a of the rotary kiln 6. This molten slag transfer path 8 is equipped with a molten slag storage container 9 at its intermediate portion. Furthermore, a spraying device 10 for spraying molten slag into the rotary kiln 6 is provided at the end of the molten slag transfer path 8 on the rotary kiln 6 side.

The molten slag transfer path 8 and the spray device 10 will be explained in more detail. A molten slag storage container 9 provided at an intermediate portion of the molten slag transfer path 8
is formed, for example, in the shape of a hollow cylinder as shown in FIG. 2, and its wall portion 9a serves as a fireproof and heat insulating wall. A first transfer pipe 8a extending from the discharge port 1a of the blast furnace 1 is connected to the upper part of this molten slag storage container 9, and a second transfer pipe 8b extending to the rotary kiln 6 and a surplus Discharge pipe 1 for discharging slag
8 is connected. These second transfer lines 8
Dampers 19 and 20 are provided on and discharge pipe 18 to open and close the respective pipes. Furthermore, a sensor 21 is provided on the upper side wall of the molten slag storage container 9 to detect the amount of molten slag stored. Then, based on the output of this sensor 21, the level controller 22 controls the discharge pipe 1.
The damper 20 of 8 is opened and closed, and the molten slag storage container 9 is opened and closed.
It is designed to maintain a predetermined amount of molten slag inside.

The molten slag storage container 9 has the function of adjusting the amount of blast furnace molten slag stored in the container 9, and adjusting the amount and temperature of the blast furnace molten slag supplied to the cement manufacturing equipment 2.

Further, as the spray device 10, for example, a device as shown in FIG. 3 is used. This spray device 10
The spout 10a opens toward the tip, and a constricted part 10b is formed in the middle part, and the constricted part 10
A second transfer pipe 8b is connected thereto to introduce the molten slag towards the pipe 8b. Further, an air supply pipe 23 is connected to the side of the spray device 10 opposite to the spout 10a. One end of the air supply pipe 23 is connected to a compressor 24, and a heat exchanger 25 is inserted in the middle. A discharge pipe 26 branched at the middle of the first transfer pipe 8a and a discharge pipe 18 extending from the molten slag storage container 9 are combined and connected to the heat exchanger 25. The initial outflow of molten slag discharged from molten slag 1 and surplus molten slag from molten slag storage container 9 are introduced.

Based on the above configuration, molten slag is quantitatively sent to the spraying device 10 from the molten slag storage container 9, and is also compressed by the compressor 24, and is brought into thermal contact with high-temperature molten slag in the heat exchanger 25. The heated air is supplied through the air supply pipe 23. Then, high-temperature molten slag is sprayed from the spout 10a toward the inside of the rotary kiln 6 using air as a spray medium.

However, in the above cement manufacturing equipment,
Cement raw materials such as limestone and silica-containing clay input from the raw material input device 28 are fed into a duct 29a connecting the first cyclone preheater 3a and the second cyclone preheater 3b, and are heated to high temperature. It is transported through an airflow and introduced into the first cyclone preheater 3a while being preheated. The cement raw material separated from the high-temperature gas in the first cyclone preheater 3a is similarly preheated via the second and third cyclone preheaters 3b and 3c, and sent to the calcining furnace 5. In the calcining furnace 5, a burner 5a burns fuel such as heavy oil or coal to preheat and calcinate the cement raw material. The cement raw material after calcination is
It is sent to the separation cyclone 4, separated from gas, and sent to the kiln bottom 6c of the rotary kiln 6. Further, the high temperature gas is sent to the cyclone preheaters 3a to 3c through ducts 29a to 29c, and is used to preheat cement raw materials.

On the other hand, the initial outflow portion of the molten slag discharged from the blast furnace 1 is sent through the discharge pipe 26, through the heat exchanger 25, to a slow cooling yard (not shown), etc., since its temperature is low. Further, the high temperature molten slag is guided into the interior of the molten slag storage container 9. A portion of the molten slag is stored inside the molten slag storage container 9 , and a predetermined amount is metered by the damper 19 and sent to the spraying device 10 . and,
The spray device 10 sprays and mixes high-temperature, high-pressure air into the cement raw material inside the rotary kiln 6 as a spray medium. The molten slag sprayed from the spray device 10 is mixed with the cement raw material,
As a result, the sensible heat possessed by the molten slag is given to the cement raw material and used as part of the heat for sintering. Here, the molten slag supplied by spraying has a large surface area, so naturally the contact area with the cement raw material is large, and therefore the conductivity to the cement raw material is high. . Further, the molten slag is sprinkled onto the cement raw material layer near the entrance of the rotary kiln 6, but the raw material is in powder form at the rotary kiln 6 entrance, and the surface of the cement raw material layer is constantly affected by the rotation of the rotary kiln 6. Since the slag is stirred and renewed, re-fusion between slag particles due to accumulation of the sprayed molten slag is prevented. The cement raw material and blast furnace slag mixed inside the rotary kiln 6 are fired to form cement clinker, which is then transferred to the clinker cooler 3.
Sent to 0.

On the other hand, the air sent into the rotary kiln 6 as a spray medium is sent as high-temperature secondary air to the firing furnace 6, calcination furnace 5, etc., and is used for preheating, calcination, and firing.

According to the above cement manufacturing method and apparatus, blast furnace slag, which has traditionally been used in the form of slow-cooled slag, rapidly cooled slag, etc., as an auxiliary raw material for cement manufacturing is sprayed and mixed in a high-temperature molten state into cement raw materials. As a result, a large amount of thermal energy of the molten slag discharged from the blast furnace can be effectively utilized by imparting it to the cement raw material and secondary air. Further, as the sensible heat is recovered from the molten slag, the fuel consumption of the cement manufacturing equipment can be reduced, and costs can also be reduced. Furthermore, since the molten slag is sprayed, pulverized, and uniformly mixed with the cement raw material, it is possible to prevent a decrease in the pulverizability of the raw material and the associated incombustibility of the cement clinker and adverse effects on equipment. Conventional cement 1
The amount of blast furnace slag added, which was limited to 100 to 150 kg per ton, can be increased to 340 to 350 kg in the case of ordinary Portland cement. According to the calculations made by the present invention, if the amount of blast furnace molten slag per ton of cement is 340 to 350 kg, the unit of limestone will decrease due to the increase in the amount of molten slag. (reduction in amount of heat produced)
Considering that, when the molten slag temperature is 1400℃, 1 kg of cement clinker has approximately 140 kcal, 1200
It is possible to reduce the firing heat by approximately 120 kilocalories in °C.

Moreover, FIG. 4 is a diagram showing another embodiment of the cement manufacturing apparatus of the present invention. In this figure, the same components as in FIG. 1 are given the same reference numerals and their explanations will be omitted.

The difference between the cement manufacturing apparatus shown in FIG. 4 and the one shown in FIG. It is a point.

That is, as shown in FIG. 5, a raw material chute 33 for introducing cement raw material from the cyclone preheater 3c is connected to a duct 32 connected to the lower part of the calciner 5, and a raw material chute of the duct 32 A spray device 31 is provided between the opening 33a of the calciner 33 and the calciner 5.

In the above configuration, the cement raw material introduced into the duct 32 via the raw material chute 33 is dispersed in the airflow blown from the clinker cooler 30 and is sent toward the inside of the calciner 5 . Molten slag is sprayed and mixed into this cement raw material by a spraying device 31, and sensible heat of the molten slag is applied. Further, the mixture of slag and cement raw material is fed into the calcining furnace 5, stirred and mixed by turbulent flow, and calcined by the burner 5a, and then sent to the rotary kiln 6 and fired.

According to the cement manufacturing apparatus as described above, the sensible heat of the molten slag is transferred to the duct 32 at the front stage of the calciner 5.
The amount of heat required for calcination can be reduced because it is added to the cement raw material. Furthermore, since the mixture of slag and cement raw material introduced into the rotary kiln 6 is completely mixed by turbulence inside the calciner 5, its uniformity is high, and the firing performance in the rotary kiln 6 is improved. .

In the cement manufacturing apparatus shown in FIG. 4, the arrangement structure of the raw material chute 33 and the spray device 31 to the duct 32 at the front stage of the calciner 5 may be the structure shown in FIG. 6 or 7. can. 6th
In the structure shown in the figure, a spray device 31 is provided at the base of a raw material chute 33 fixed obliquely to the duct 32, with its spout 31a facing the inside of the duct 32. Further, in the structure shown in FIG. 7, a spray device 31 is coaxially provided near the base inside a raw material transport pipe (raw material chute) 33 fixed at a substantially right angle to a duct 32, and its spout 3
1a is installed toward the inside of the duct 32.

In the structure shown in FIG. 6, the molten slag sprayed into the duct 32 is
collides with the flowing raw material layer and exchanges heat. At this time, the slag particles stall and collisions occur between particles, but if the temperature is about 900° C. or lower, there is no risk of fusion. Further, even if some fusion occurs, other raw material particles will also adhere to the surface of the molten slag particles that collided with the raw material layer, so the raw material composition will be uniform and there is no fear that it will be difficult to burn inside the rotary kiln 6.

In addition, in the structure shown in FIG.
The molten slag is quickly and efficiently mixed with the molten slag sprayed from the air stream, and then introduced into the duct 32.

According to these structures, the mixing efficiency of the cement raw material and the molten slag can be increased, and the firing performance in the firing furnace is not impaired.

In addition, in the above-mentioned example, an example was explained in which blast furnace molten slag is sprayed and mixed into cement raw material in a calcining furnace and a firing furnace, but it is not limited to these examples. , may be mixed.

As described above in detail, the method and apparatus for producing cement using blast furnace molten slag according to the present invention includes providing a molten slag transfer path between the molten slag discharge port of a steelmaking blast furnace and cement production equipment, and The molten slag conveyed through the molten slag transfer path is sprayed and mixed with the cement raw material by a spraying device in a preheater, a calcining furnace, or a firing furnace of manufacturing equipment, or a duct at the front stage of any of these furnaces. Molten slag, which has traditionally been used as an auxiliary raw material in cement manufacturing, is introduced into the cement manufacturing process in a high-temperature molten state, and its sensible heat is used as part of the preheating heat, calcination heat, or firing heat. This makes it possible to effectively utilize the large amount of thermal energy contained in blast furnace molten slag, which has not been sufficiently recovered in the past, and to reduce the amount of heat required by cement manufacturing equipment, which means saving fuel. be able to. Further, along with this, cement manufacturing costs can be reduced.
Furthermore, since the molten slag is sprayed and mixed with the cement raw material inside the calciner of the cement manufacturing equipment or in a duct at the front stage of the calciner, the surface area of the supplied molten slag is increased by spraying. ,
This increases the contact area of the molten slag with the cement raw material, increasing the heat transfer efficiency to the cement raw material, and also allows the cement raw material and slag to be thoroughly mixed and homogenized inside the calcining furnace. This brings about effects such as making it easier to fire inside the firing furnace.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of the present invention, FIG. 2 is a sectional view showing an example of a molten slag storage container, FIG. 3 is a sectional view showing an example of a spraying device, and FIG. 4 is a sectional view showing an example of a spraying device. 5 is a schematic configuration diagram showing another embodiment of the present invention, FIG. 5 is a sectional view showing an example of the structure of the installation part of the spraying device in cement manufacturing equipment, and FIGS. 6 and 7 are views of the same structure. It is a sectional view showing other examples. 1... Steelmaking blast furnace, 1a... Molten slag discharge port,
2... Cement manufacturing equipment, 5... Calcining furnace, 6...
Calcining furnace (rotary kiln), 8... Molten slag transfer path, 8a... First transfer pipe, 8b... Second
transfer pipe line, 9...molten slag storage container, 10,
31... spray device, 10a, 31a... spout,
19, 20... damper, 23... air supply pipe, 24...
... Compressor, 25 ... Heat exchanger, 32 ... Duct, 33 ... Raw material chute.

Claims (1)

[Claims] 1. Blast furnace molten slag discharged from a steelmaking blast furnace,
The molten slag is introduced into cement manufacturing equipment through a transfer path, and the blast furnace molten slag is quantitatively sprayed and mixed with the cement raw material in the preheating process, calcination process, or firing process of the cement manufacturing equipment, and the sensible heat of the blast furnace molten slag is absorbed. A method for producing cement using blast furnace molten slag, characterized in that it is fed to the cement raw material. 2. The molten slag transfer path includes a molten slag storage container in an intermediate portion, and a predetermined amount of the blast furnace molten slag introduced into the molten slag storage container is guided to the cement manufacturing equipment, and the remainder is stored or discharged. A method for producing cement using blast furnace molten slag according to claim 1. 3. The method for producing cement using blast furnace molten slag according to claim 1 or 2, wherein the firing step is performed by a rotary kiln, and the blast furnace molten slag is sprayed into the rotary kiln. 4. The calcination step is performed in an air flow furnace type calcination furnace, and the blast furnace molten slag is sprayed inside the calcination furnace or inside a duct near the entrance of the calcination furnace. A method for producing cement using blast furnace molten slag according to item 2. 5. A molten slag transfer path is provided between the molten slag discharge port of the steelmaking blast furnace and the cement manufacturing equipment, and at one end of the molten slag transfer path, a preheater, calcining furnace, or firing furnace of the cement manufacturing equipment is installed. Production of cement using blast furnace molten slag, which is equipped with a spraying device for quantitatively spraying the blast furnace molten slag into the interior or inside of a duct that introduces cement raw materials into these preheaters, calcining furnaces, or firing furnaces. Device. 6. The cement manufacturing apparatus using blast furnace molten slag according to claim 5, wherein the molten slag transfer path is provided with a molten slag storage container at an intermediate portion. 7. A cement manufacturing device using blast furnace molten slag according to claim 5 or 6, wherein the firing furnace is a rotary kiln, and the spraying device has a spout facing toward the inside of the rotary kiln. . 8. The calcining furnace is an air flow furnace, and the spraying port of the spray device is installed toward the inside of the calcining furnace or the inside of a duct for introducing cement raw materials into the calcining furnace. A cement manufacturing apparatus using the blast furnace molten slag according to claim 5 or 6.