JPS5861203A - Method for producing amorphous blast furnace slag and recovering retained heat - Google Patents

Abstract

PURPOSE:To produce slag contg. amorphous materials at specific rates stably in the stage of cooling molten blast furnace slag by a dry system or the like by cooling the slag at specific cooling rates down to specific temps. thereafter cooling the same slowly stepwise down to specific temps. at a specific cooling rate. CONSTITUTION:In the stage of cooling molten blast furnace slag by a dry system or gas/liquid system, the slag is cooled quickly at >=20.0 deg.C/sec cooling rate down to 1,200 deg.C from right after the start of cooling by granulating the slag by the flow of gases or mists., and the hot wind thereof is recovered. Thereafter, the slag is cooled stepwise as slowly as possible at >=5.8 deg.C/sec cooling rate from 1,200 deg.C down to 1,100 deg.C, at >=2.5 deg.C/sec from 1,100 deg.C down to 1,000 deg.C, and >=0.3 deg.C/ sec from 1,000 deg.C down to 850 deg.C, and the hot wind is recovered. Thus the heat retained by the slag is recovered advantageously and easily, and the slag contg. >=95% amorphous materials is produced stably.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for stably producing slag with an amorphous ratio of 95 or more when cooling molten blast furnace slag using a dry method or an air-water method, and a method for stably producing slag with an amorphous content of 95 or more when cooling molten blast furnace slag using a dry method or an air-water method. It concerns a method of recovering the heat retained in the death lag.

After cooling, the blast furnace slag generated during manufacturing is used as raw material for cement, road materials, fine aggregate for concrete, etc. When used as a raw material for cement, the standard requires that the amorphous content be 95 or more.

The demand for amorphous slabs as a raw material for cement is likely to increase in the future.

Currently, the proportion of amorphous materials used as raw materials for cement is 9
The production of slag of 51 or higher is by a granulation method using a large amount of water treatment. This slag after water pulverization has an amorphous ratio of 9
It is stable at 5 or more.

On the other hand, energy conservation has become an important issue due to the energy situation in recent years.

For this reason, attempts have been made to recover the enormous amount of heat retained in the molten slag. However, when recovering the heat retained in the molten blast furnace core using the fracking equipment, a large amount of water is used, and the slag temperature and water temperature after treatment are low, making it technically difficult to recover the heat.

For this reason, rather than using a large amount of water for cooling, for example, a small amount of 2-stroke water or a dry method that does not use any water is used to cool the slag to the extent that it does not interfere with the recovery of the heat retained in the slag. There is a need for a method for producing raw materials for cement that recovers the heat retained in slag and in which the slag after cooling has an amorphous ratio of 95 or more. It has been said that slag can be produced by cooling molten blast furnace slag at a temperature of 110°C or higher.

That is, for example, in the example of the dry granulation slab shown in Japanese Patent Publication No. 55-43412, the temperature of lO
It is said that amorphous slag is obtained at a cooling rate of 10° C./sse or higher, and crystalline slag is obtained at a cooling rate of less than 10° C./m@e. However, these known dry cooling methods that do not rely on water cooling have the disadvantage that they cannot stably produce slag with an amorphous content of 95% or more.

On the other hand, as a treatment method for the purpose of heat recovery of molten blast furnace slag, a method of injecting it into a casting m and recovering the retained heat after solidification has been considered.

However, with this method, it takes a long time to solidify the molten slag, and it is difficult to recover heat at high temperatures.
It has drawbacks such as the slag crystallizing after cooling.

There has also been an attempt to granulate the molten blast furnace slag and recover heat while maintaining the granular slag type 071. However, with this method, it is necessary to cool the granulated slag to a temperature close to 900°C, which is a temperature that prevents re-fusion, to prevent fusion of the granulated slag. This has the disadvantage that the equipment becomes larger.

In addition, some measure to prevent fusion of KFI, which collects high-temperature granulated slag, is required.

Furthermore, the slag grains are small, and there are many drawbacks such as requiring a high level of technology when heat is recovered in a fluidized bed or packed bed, making it difficult to stably obtain t-9 amorphous slag, and it has not been put into practical use. Currently, there are only a few examples.

As a result of repeated experiments under cooling conditions that do not rely on conventional large amounts of water cooling, the present inventors found that the cooling rate from the cooling start temperature of molten blast furnace slag to 1200C is important, and that the cooling rate 1 during this period is important. If the rate is controlled to 20.0°C/sec or more, slag with an amorphous ratio of 9596 or more can be stably obtained, and cooling from 1200°C to 850°C is faster than conventionally known cooling rates. It has been found that the amorphous fraction obtained up to 1200° C. can be maintained at a much slower rate.

As a result, molten blast furnace slag can be granulated up to 11,200 degrees Celsius by being granulated by air flow or mist flow at 20.0 degrees Celsius/s.
It is possible to rapidly cool the granulated slag to above ee and recover the heat while cooling it relatively slowly below 200°C, and obtain the slag with an amorphous ratio of F(- or more) after cooling. Tonatsu nine.

In this way, the present invention rapidly cools to 1200°C,
℃ or below, heat is recovered while slowly cooling, and slag with an amorphous ratio of 95 or more is produced.

In the most preferred embodiment of the present invention, the molten slag is rapidly cooled at 1200°C immediately after the start of cooling while being granulated with an air flow to obtain an amorphous slag, and after that, the slag particles after falling are fused. This method recovers retained heat while cooling relatively slowly in the next state. Therefore, the slag grains at the point of fall need only be heated to a relatively high temperature to be fused, and the space from the start of granulation to the point of fall may be small, and as a result, there is an advantage that the equipment can be marked.

Furthermore, when granular slag fuses and becomes lumpy, heat recovery methods such as fluidized bed or packed bed can be applied to recover retained heat during overcooling, applying technology that has been put into practical use in other fields. It can be easily put into practical use.

In addition, since the slag after cooling can be recovered as having an amorphous content of 95% or more, it has the advantage that it can be used as a raw material for cement, whose demand is expected to increase by 2. As described above, the advantages obtained by the present invention are elevenfold.

This will be explained below based on the experimental results.

Blast furnace slag was melted in a device shown in No. 1111K, gold IIK was injected into the melted slag, and the cooling rate was varied to cool the slag.

The cooling rate was adjusted by learning the temperature of the IIFi mold.

Table 1 shows an example of the results of the cooling rate and the proportion of amorphous in the slag after cooling.

As is clear from Experiments 41, 2, and 3, in order to obtain slag with an amorphous content of 959C or higher, heating from 1400℃ to 12
It can be seen that at 00C1, it is necessary to increase the cooling rate to t20.0°C/s@s+ or higher.

Also, from J16g, 7, 8, 9, and 10, the K to be maintained as a slag with an amorphous ratio of 951C or more is 1200
The cooling rate from ℃ to 850℃ is 5.8℃/l@l1 or more from 1200℃ to 1100℃, 7 mouths or more at 2.5 from 1100℃ to 1QOO'c, 0.3 from 1000℃ to 850C It turns out that /see or more is required.

In addition, the cooling rate from 1400℃ to 1200℃ is 20℃.
．． It is clear from 43, 4, and 5 that when the temperature is less than 0°C/I@@, a slag with an amorphous ratio of 9511 or more cannot be obtained regardless of the slow cooling rate below 1200°C.

In addition, 46 in Table 1 indicates t from 1400°C to 1200°C.
201) This indicates the lower limit of the cooling rate to obtain an amorphous slag of 95% or higher when rapidly cooling with C/s@e and cooling slowly below 1200°C, and O:
S degree〉 9 with slow cooling! It is impossible to obtain more than amorphous slag.

The present invention attempts to cool the slag at a rate close to the lower limit cooling rate to obtain a slag with an amorphous content of 9511 or more, and at the same time recover the heat retained in the busy slag. Therefore, in the present invention, it is preferable that the upper limit of the cooling rate in each temperature range of 1200° C. or lower be equal to or lower than the conventionally known cooling rate shown in Table 1, for example, as shown in Table 1. It is possible to convert the molten slag into concrete, and the heat retained in the molten slag can be advantageously recovered.

Next, a case will be described in which the molten slag is cooled while being granulated.

Using the apparatus shown in Fig. 2, molten blast furnace slag 12 at 1400°C is dropped from Tandigy 11 at a throughput of 0-2 k#/s@a and granulated by an air flow of 2600 wt''/sufda t from air nozzle 13. It was cooled by

In this case, the cooling rate is around 1200C, 20~b The granular slag 14 falls onto the iron plate 15 and is fused thereto.

The temperature of the granular slag when it falls onto the iron plate is around #11200°C.

The temperature of the fused slag 16 is measured with a thermocouple 17 and recorded with a recording needle 18.
It was recorded in The fused slag was collected by tilting the iron plate downward with the upper and lower arms 19. Table 2 shows an example of the results of the cooling rate and the amorphous ratio of the fused slag after cooling.

As is clear from Table 2, the cooling rate from 11400C to 1200C1't' is 20.0℃/I・or more, 1200C
From ℃ to 1100℃ 5.8℃/I@1! Above, 11
From 00℃ to 1000C1't't-2,5℃/sec or more, from 1000℃ to 5so: ma"t"t-0,3℃/
It has been found that if the slag is cooled at a temperature of as++ or higher, a slag with an amorphous content of 95% or more can be obtained even after cooling is completed, similar to the experimental results described above.

The present inventors based on the above knowledge
lf, he came to invent a method for preparing slag with an amorphous content of 95s or more, and a method for recovering the retained heat of molten blast furnace slag to a volume S.

Figure 3 shows the slag cooling process when carrying out this invention.
This shows an example of a heat recovery method in K.

Molten blast furnace slag 371 Slag 22 obtained by granulating with air nozzle 21 Until near Fi1200C, 20.0 ° C / s
It is cooled at a speed higher than @, falls onto the steel belt 23, and is fused.

After fusion, adjust the moving speed of the slag and /I in Table 1.
The amorphous state is maintained by maintaining the cooling rate above the lower limit cooling rate shown in i6 and cooling relatively slowly.

The fused slag 24 is roughly crushed by a coarse crusher 25 .

In many cases, the sludder grains are close to point fusion, and are easily crushed.

Rough crushing is carried out at a temperature around 900° C. at which no fusion occurs.

26 roughly crushed slags are conveyed by a bucket conveyor 27 and charged into a packed bed 30 through upper and lower bells 28, 291.

Air is blown in from an air suction port 31 and hot air is recovered from a hot air blowout port 32. Since the slag is in the form of lumps, the heat recovery technique in this case can be easily put to practical use by appropriately applying existing techniques used for recovering heat such as the heat retained in coke. Further, the air during granulation is recovered as hot air from the hot air outlet 33. After cooling, the slag 3411 is cut out by the belt feeder 35 and collected.

This slag has an amorphous ratio of 954 or more and can be used as a raw material for cement.

The method for cooling molten blast furnace slag at 120D℃t immediately after the start of granulation is not only by air flow, but also by using a small amount of water, such as air and water, as long as it does not hinder the recovery of the heat retained in the molten slag. It is also possible in the flow.

As explained above, the present invention has an amorphous ratio of 9591
This was done based on the discovery of the ninth new cooling rate limit for stably producing slag, and as a result, it was possible to obtain amorphous slag using a conductive device, and at the same time reduce the retained heat of molten slag. It is possible to recover JIK in an advantageous manner, and its industrial merit is the biggest! It's a good thing.

[Brief explanation of drawings]

Figure 2 shows an experimental device for injecting molten blast furnace slag into a mold and cooling it. , FIG. 3 is a longitudinal sectional view showing an example from granulation to a heat recovery device for carrying out the present invention. l...rotary melting furnace, 2...burner, 3...
・S melting blast furnace nlug, 4...cooling slag, 5...
Mold, 6... Mold lid, 7... Thermocouple, 8- Recorder, 9... Electric iP, 11
... Tanpuiside 12 ... Molten blast furnace slag, 13.
- Air nozzle, 14... Granular slag, 15...
・Iron plate 16... Fusion slag, 17... Thermocouple, 18... Recorder, 19... Upper and lower arms, 21... Air nozzle, 22... Granular slag, 24... Fusion Adhesive slag, 23... Steel belt conveyor, 25... Roughly crushed slag, 26-- Roughly crushed fused slag, 27... Packet conveyor, 28... Upper shell, 29
...Lower Pel, 30...Filled layer, 31...
・Air inlet, 32... Hot air outlet, 33.
...Hot air outlet, 34...Slag after cooling, 35
...Belt feeder, 36...Tampuiside, 37
...Melted blast furnace slag. Figure 1

Claims (4)

[Claims] (1) When cooling high melting desladder using dry method or gas-liquid method, cooling #I 1200t immediately after production starts: 2a
At O/I@@ or more, 1200ctP et al. 1100℃t
ts℃/-...more than 1100C to 1000C1k
"1" t l S Ic / s@e or more, 1000
A method for producing an amorphous blast furnace mold having a proportion of amorphous of 9s or more, which involves cooling from 0C to 8500C at a cooling rate of at least α3C/-axis. (2) When cooling molten blast furnace slag, 1! immediately after the start of cooling. OO1: To make t grains, K means 20
．． 0℃/hata... or more, quench cooling, temperature range below 1200C from 1200℃ to 1100℃ t&, 8C/s** or more, 1100℃ to 1000C1f to 15℃/-・1% or more from 1000℃ to m5oct 0.3℃/-・・
A method for recovering retained heat at the same time as producing amorphous blast furnace slag with an amorphous content of 9-5 s or more, characterized in that the retained heat of the slag is recovered while cooling the slag as slowly as possible at the above cooling rate. . (3) A method for recovering retained heat at the same time as manufacturing amorphous blast furnace slag according to claim 2, which cools granular slag to 1200°C or less in a fused state. (4) A method for recovering the retained heat of the slag simultaneously with the production of amorphous blast furnace slag according to claim 2, wherein the retained heat of the slag is recovered at an arbitrary temperature range within each temperature range where the cooling rate is different.