JPS5943533B2 - Method for producing sintered ore - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sintered ore that makes it possible to shorten the actual sintering time in the sintering process.

Generally, sintered ore is made by homogeneously mixing various sintering raw materials in the required ratio, and then adding water, hot water, or a pseudo-granulating agent (binder) to the mixture.
is added, kneaded and granulated using a drum, mixer, etc. to coarsen the pseudo particles, then charged into a sintering machine, ignited in the sintering machine to cause a sintering reaction, and complete sintering. This is then crushed and cooled to produce it.

By the way, it is no exaggeration to say that the production rate of sintered ore depends on the shortening of the actual sintering time, and various methods such as improving air permeability have been tried to shorten the actual sintering time. As described above, kneading and granulating the sintering raw material to coarsen the pseudo particles is one method for improving air permeability.

However, a single drum mixer is not enough to sufficiently coarsen the pseudo-particles; multiple drum mixers are required, equipment costs are high, and even if the particles are coarsened, they will collapse during the sintering process. The sintering time could not be sufficiently shortened due to the large amount of sintering, which impeded ventilation.

The reason why the pseudo particles collapse during the sintering process is as follows.

In general, sintered raw materials with coarse pseudo-particles, for example, in a Dwight Lloyd sintering machine, are sequentially charged and filled to the required height on the pallet, then ignited on the surface, and simultaneously moved to the pallet. By suctioning air through a wind box placed below the area, the air is blown downward from the surface of the sintered packed layer on the pallet, and the sintered packed layer is sintered sequentially downward from the surface. In the sintering process, a sintering zone A, a drying zone B, a moisture condensation zone C, and an initial sintering raw material zone are formed in the sintered packed bed from the surface side downwards, as shown in FIG. Ru.

The sintering zone A is an area where sintering has already been completed, and the drying zone B is an area that is being heated and dehydrated by the high-temperature exhaust gas flowing downward through the sintering zone A, and is further a moisture condensation zone. C is a region where the exhaust gas containing moisture is cooled in the drying zone B and the moisture is condensed, and the initial sintering raw material zone is a sintering raw material zone where the initial sintering raw material zone is still charged and filled.

FIG. 8 is a graph showing the moisture distribution in the cross section of the sintered packed bed 45 seconds after ignition on the surface of the sintered packed bed, with the horizontal axis representing moisture and the vertical axis representing the height of the sintered raw material. The center of the graph shows the surface of the sintered packed layer.

As is clear from this graph, the moisture content of the sintered raw material, which had an initial moisture content of 5.8%, decreased to zero in the sintering zone A, and in the dry zone B, the moisture content rapidly decreased from the bottom upwards. Furthermore, although the moisture content does not change in the initial sintering raw material zone, it can be seen that the moisture content in the moisture condensation zone C increases by about 2% from the initial moisture content.

This increase in moisture in the moisture condensation zone C brings the pseudo particles into an excessive moisture state, causing them to collapse and become fluidized, closing the gaps between the pseudo particles and impeding air permeability.

Incidentally, an example of the ventilation resistance coefficient (103 m-1) in each region is shown below, and it can be seen that the resistance in the water condensation zone C is significantly large.

Sintering zone A: 23.20 Drying zone B: 57.77
Moisture condensation zone C: 78.28 Initial sintering raw material zone D: 23.
20 As a countermeasure for this, there is a method of reducing the amount of water or hot water in the mixing process of sintering raw materials, or a method of reducing the amount of water or hot water in the mixing process of sintering raw materials, or 3)
A method of preheating and drying by passing exhaust gas around 00°C for 10 to 30 seconds, followed by ignition and sintering (Japanese Patent Application Laid-Open No. 55-738
No. 34) etc. have been proposed.

However, in the former method, it is not possible to make the grains coarse enough, and the strength of the coarse grains is low and they collapse easily. Although the effect of reducing particle collapse, improving air permeability, and shortening the actual sintering time is recognized, on the other hand, this preheating and drying is performed on the pallet of the sintering machine, so the pallet for sintering is The effective area is reduced,
As a result, the current situation is that the production rate remains almost unchanged.

The present invention was created in view of the above circumstances, and its purpose is to knead sintering raw materials to coarsen pseudo particles, dry them so that the dry moisture removal rate is 40 coefficients or less, and then By charging the sinter into the sintering machine, the production rate and quality of sintered ore can be greatly improved, and NO
It is an object of the present invention to provide a method for producing sintered ore that can also reduce the amount of x generated.

Hereinafter, the present invention will be explained in detail based on the drawings. Figure 1 is a block diagram showing the process order of the method for producing sintered ore according to the method of the present invention (hereinafter referred to as the method of the present invention), and Figure 2 is a block diagram of the sintered raw material. This is a schematic diagram showing the drying and charging process, in which 1 is the measuring and cutting process of the sintering raw material, 2 is the mixing process of the sintering raw material, and 3 is the process of adding water, hot water, or a pseudo-granulating agent. A granulation process for coarsening the pseudo particles, 4 a drying process, 5 a charging process to a sintering machine, and 6 a sintering process.

First, various sintering raw materials are weighed and cut out according to preset mixing ratios (weighing/cutting process 1), mixed homogeneously in a bag mill, etc. (mixing process 2), and the mixed sintering raw materials are The mixture is kneaded in water, hot water, or a pseudo-granulating agent in a drum mixer, and granulated to coarsen the pseudo-particles (granulation step 3).

The degree of coarsening of the pseudo particles relative to the pseudo particles is appropriately set so that sufficient strength as particles can be maintained and sufficient ventilation function can be obtained.

The sintering raw material that has undergone coarsening of pseudo particles is introduced into the surge hopper 41 as shown in FIG. 2, and is supplied from the surge hopper 41 onto the pallet 42a of the sintering machine 42. The sintering raw material is dried in 41 (drying step 4).

The surge hopper 41 is located above one end of the sintering machine 42, that is, the ore feed end, and is located immediately downstream of the bedding hopper 43, and has a roll feeder 41a and the ore cut from the roll feeder 41a at its feed opening. Pallets of sintered raw materials) 4
A deflector plate 41b is provided that guides the deflector onto 2a.

The bedding hopper 43 is supplied with bedding ore, and the surge hopper 41 is supplied with the above-mentioned sintering raw material.
The bedding ore is supplied from 3, and the sintering raw material is supplied from the surge hopper 41 over the bedding ore over the required height.

By the way, the inside of this surge hopper 41 has a head-like shape as a whole above the outlet, and a large number of injection holes 41 are provided on the upper surface.
A hot air blowing nozzle 41d with an opening C is provided.

One end of a hot air supply pipe 41e penetrating the peripheral wall of the surge hopper 41 is connected to the blowout nozzle 41d, and the other end is connected to the air box 4 of the sintering machine 42 with a blower 41f interposed in the middle.
The exhaust duct 45a is connected to the exhaust duct 45a.

The sintered exhaust gas (approximately 80 to 120°C) sucked and collected through each wind box 45 flows through the exhaust duct) 45a, and this flows through the blower 41f and the hot air supply pipe 41e to the surge hopper 41 from the injection hole 41c of the blowout nozzle 41d. It is designed to be ejected inwardly and upwardly.

The exhaust gas blown into the surge hopper 41 flows upward through the gaps formed between the pseudo particles of the sintering raw material.

As a result, the sintered raw material is dried until the dry moisture removal rate - defined by the following formula becomes 40% or less.

The reason why the dry moisture removal rate (a) is set to 40 factors or less is because if it exceeds 40 factors, the strength of the pseudo particles will decrease rapidly (see Figure 4) and the pseudo particles will collapse in the moisture condensation zone during the sintering process. Easy,
In addition, the rate of change in the sinter production rate decreases (see Figure 5), the reduction powdering rate increases (see Figure 6), and the N
The amount of Ox generated will increase rapidly (see Figure 7).

The above pseudo particle strength (a) is 5 to 2 mm pseudo particle 2.
00g and the weight (g) of pseudo particles of 5 to 2 mm after dropping this 10 times from a height of 1 m onto a 10 mm thick iron plate (g).

The pallet 42a of the sintering machine 42 is a driving sprocket 42d.
An ignition furnace 44 is located above the movement area of the pallet 42a on the downstream side of the surge hopper 41. , and below is the ignition furnace 4.
A wind box 45 is arranged in series from a position facing 4 to near the discharge end (not shown), sucks the wind with a flap (not shown), and blows the wind downward from the surface of the sintered packed bed.
The sintered material is sequentially sintered from the surface downward in an ignition furnace.

Figure 3 shows the surface of the sintered packed bed of the raw material with a dry moisture removal rate of 25% for the raw material moisture content after granulation of 5.7% after ignition.
Moisture in the cross section of the sintered packed bed after seconds have elapsed (a)
This is a graph showing the measurement results of , where the horizontal axis shows moisture (A) and the vertical axis shows the height of the sintered packed layer (mm), where the middle part of the graph is the sintered zone and B is the dry zone. , C is the water condensation zone,
D indicates an initial sintering raw material zone.

As is clear from a comparison between this graph and the graph for the conventional method shown in FIG. The coefficient is about 4.5, which means that the moisture in the moisture condensation zone C is significantly reduced, and the disintegration and fluidization of pseudo particles in the moisture condensation zone C will be suppressed to that extent. This can be easily inferred.

Next, various test results using the method of the present invention will be explained.

In the test, test materials t, n, and m having three types of blending ratios as shown in Table 1 were used, and coke powder was added at 3.75%.
%, and when kneading, add 5.0% water to sample material ■, 5.5% water to sample material H, and 6.0% water to sample material ■, using a concrete mixer (inner diameter 600mm, length 60
0 mm) and was driven at 24r, p, m, kneaded and granulated for 4 minutes, and had particle size distributions as shown in Table 2, respectively. Test material■(
A fine grain raw material) was obtained.

Next, various drying moisture removal rates (a) were set in a dryer maintained at approximately 105°C, and this was dried in a sintering test pot (top inner diameter 300 mm, bottom inner diameter 280 mm, height 4007 nm).
The material was ignited and sintered.

The results are shown in Figures 4-7.

FIG. 4 is a graph showing the relationship between pseudo particle strength and dry moisture removal rate, with the dry moisture removal rate (A) on the horizontal axis and the pseudo particle strength (A) on the vertical axis. In the graph■
indicates the results for the sample material ■, ■ indicates the results for the sample material ■, and ■ indicates the results for the sample material ■.

As is clear from this graph, sample material 1. In both cases II and H, the drying moisture removal rate in the drying process (a)
When exceeds 40%, the pseudo particle strength decreases rapidly, but
In the method of the present invention, since the dry moisture removal rate (a) is set to 40% or less, it can be inferred that the strength of the pseudo particles is high and that it is possible to prevent the particles from collapsing during the sintering process.

Figure 5 is a graph showing the relationship between the production rate of sintered ore and the dry moisture removal rate. The production rate at 0 is 100).
n and III are sample materials I, respectively.

The results of ■ and ■ are shown.

As is clear from this graph, sample material 1. For both No. Since the drying moisture removal rate is set to 40% or less, it is possible to significantly improve the production rate.

Also, sample material 1. In comparison between No. n and III, the larger the degree of coarse graining, the higher the production rate.

Figure 6 is a graph showing the relationship between the reduction pulverization rate and the dry moisture removal rate, which are important indicators of sintered ore quality, with the dry moisture removal rate on the horizontal axis and the reduction pulverization rate on the vertical axis. 1 in the graph. II and III are sample materials 1. n,
The results of H are shown.

As is clear from this graph, sample material 1. When the dry moisture removal rate exceeds 80% for II and 60% for test material II, it rapidly decreases, but in the method of the present invention, the dry moisture removal rate can be reduced to 40% or less. It can be seen that the reduction and powdering rate can be significantly improved by setting the following conditions.

Also, sample materials 1 and II. ■In mutual comparison, the dry moisture removal rate (
It can be seen that b) has the largest effect.

FIG. 7 is a graph showing the relationship between the amount of NOx generated during the sintering process and the dry moisture removal rate. In the graph, 1, n, and 111 indicate sample material 1.1, n, and 111, respectively.
The results for II and III are shown.

As is clear from this graph, supply material 1. II, III
Both show the lowest values when the dry moisture removal rate is around 20 units, and when the dry moisture removal rate exceeds 70 to 90 units, the amount of NOx generated becomes larger than conventional methods, but in the method of the present invention, the dry moisture removal rate Since it is set to 40 sections or less, NO
This makes it possible to significantly reduce the amount of x generated.

In comparing sample materials 1, n, and III, the smaller the raw material particle size, the smaller the amount of NOx generated.

In addition, in the above-mentioned embodiment, a configuration was shown in which drying is performed using the surge hopper 41 for supplying the sintering raw material after granulation to the sintering machine, but the invention is not limited to this in any way. After installing a dryer and drying the sintering raw material to the required dry moisture content (a),
It may also be introduced into the surge hopper 41.

Furthermore, although the embodiments have described a configuration in which sintering exhaust gas is used as a heat source for drying, it goes without saying that exhaust gas from various types of furnaces may be used.

As described above, in the method of the present invention, the sintering raw materials are kneaded and granulated, dried so that the dry moisture removal rate is 40 coefficients or less, and then charged into the sintering machine. The effective area for sintering in the sintering machine is not reduced in any way, and even in the moisture condensation zone during the sintering process, the increase in moisture is significantly suppressed and the collapse of pseudo particles is prevented.
Ventilation during the sintering process is not obstructed, and sintering productivity can be improved by significantly shortening the actual sintering time. Also, it is possible to improve the reduction powdering rate and control the amount of NOx generated. The present invention has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the method of the present invention in the order of steps, FIG. 2 is a schematic diagram showing the drying process and charging process, and FIG. 3 is a graph showing the moisture distribution of the sintered packed bed during the sintering process. 4 to 7 are graphs showing the test results for sintered ore and intermediate products according to the method of the present invention, and FIG. 8 is a graph showing the moisture distribution during the sintering process according to the conventional method. 1...Measuring, cutting process, 2...Mixing process, 3...Pelletization process, 4...Drying process, 5...・Charging process, 6...Ignition sintering process, 41...Surge hopper, 41a...
・Roll feeder, 41b... Deflector plate, 41c... Injection hole, 41d...
・Blowout nozzle, 41e... Supply pipe, 41f...
...Blower, 42...Sintering machine, 43...
...Bedding hopper, 44...Ignition furnace, 45...
...Wind box, 45a...Exhaust duct.

Claims (1)

[Claims] 1. Knead the sintering raw materials to coarsen the pseudo particles, dry them so that the dry moisture removal rate shown by the formula below is 40% or less, and then charge them into the sintering machine. Characteristic method for producing sintered ore. Dry moisture removal rate (a)