JPS5928612B2 - Sintered ore manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the method of obtaining sintered ore using a Dwight Lloyd sintering machine.

When producing sintered ore using a Dwight Lloyd sintering machine, the conventional method is to feed the sintered raw material at room temperature into an ignition furnace that is heated to over 1000°C, where the surface layer of the raw material is ignited, and air is sucked in from below. By doing so, the pallet speed was controlled so that the sintering reaction zone moved downward and the sintering reaction was completed over the entire layer near the ore discharge area.

However, the sintering reaction itself is not fully understood, and many tasks, such as determining when sintering is complete, rely on the intuition of the operator, and many problems still remain in the sintering reaction process.

Furthermore, in a situation where energy issues have been in the spotlight recently, the entire sintering process is being reconsidered with an eye toward energy conservation.

Looking at the sintering process from the perspective of energy conservation, the majority of the heat source required in the sintering process comes from fuels such as coke powder and ignition heat sources, which are mixed in a few percent of the raw materials. One of the major challenges is to reduce the ratio.

If this could be achieved, it would bring about a very large effect, but lowering the blending ratio of the fuel unnecessarily will not yield good results.

In other words, even if fuel is saved, the quality of the sintered ore produced must not deteriorate, the amount of returned ore must not increase, and the production efficiency must not be significantly reduced.

In the end, there is no point in producing high-quality sintered ore efficiently and at a low price.

In addition to the fuel, the moisture contained in the raw material, the particle size of the raw material, and the amount of air blown have important meanings in the sintering process. Because of this, we tend to think that it is better to reduce the amount of water as much as possible, but the water added to the raw material plays a role in indirectly improving air permeability, and in this sense, it is indispensable.

What would happen if we added a certain amount of moisture to a raw material consisting of powder and granules, mixed them to create a sintered raw material, gave it appropriate air permeability, and then dried and sintered the raw material to produce sintered ore. Although there have been some studies conducted, it has been reported that there was almost no difference compared to the case using the normal sintering method.
There is also a contrary research report in JP 8-38521 which states that there is a positive correlation between the water content in the sintered raw material and the amount of sintered ore produced per hour.

As described above, even if we look only at the water content in raw materials, it is complicated, and there are still many problems that need to be solved regarding sintering as a whole.

The present invention focuses on improving air permeability during the sintering process, and has been researched based on new ideas, and has significantly improved sintered ore production efficiency and made it possible to reduce fuel consumption. In a method for manufacturing sintered ore using a Lloyd type sintering machine, dry gas at room temperature to 2500 C is supplied to the surface layer of the charge supplied onto a pallet, and air is sucked in from below to dry only the surface layer of the charge. This method of producing sintered ore is characterized in that a dry zone is formed on the surface layer of the charge, and then the dry zone is ignited.

The present invention will be described in detail below based on the drawings.

FIG. 1 is a conceptual diagram of a sintering process explaining the present invention in detail.

As shown in FIG. 1, the present invention continuously supplies a sintered raw material 1 from a hopper 2 to a drum feeder 3 and onto a pallet 7 via a sloping plate 5 and a sprocket 4 on the raw material supply side.
is rotated to move the charge (raw material) 8 on the pallet γ at low speed.
Air is sucked in by the suction fan 12, and the upper surface of the charge 8 is ignited in the ignition furnace 6, so that the sintering reaction is completed over the entire layer while the charge 8 on the pallet γ reaches the ore discharge section. In a Dwight Lloyd type sintering machine that produces sintered ore, a dry gas supply device 19 is installed between the ore feeder (hopper 2, drum feeder 3, sloping plate 5) and ignition furnace 6, and the charging Before the material 8 enters the ignition furnace 6, dry gas is blown onto the upper surface of the charge 8, air is drawn in from below to form a dry zone in the upper layer of the charge, and then ignited in the ignition furnace 6. The purpose is to produce sintered ore.

In a conventional sintering machine, the charge placed on the pallet 7 is put into an ignition furnace that is heated to over 1000°C, and the charge at almost room temperature is suddenly exposed to a high-temperature flame and burns extremely rapidly. Because the temperature was raised and ignited, the top surface of the charge was subjected to a large thermal shock.Therefore, by adding a few percent of water to various raw materials consisting of powder and granules, the surface layer of the charge was made to have pseudo-granulation and improved air permeability. The pseudo grains were destroyed and the air permeability was significantly impaired.

Then, the sintered completed layer and the reaction surface formed on the surface grow and move downward, and air continues to be sucked in from the lower wind box until the sintering reaction completes over the entire layer near the waste minerals, which causes the ignition furnace to emit air. The deterioration of air permeability in the surface layer remained in effect until the end of sintering.

The destruction of pseudo-grains on the surface layer of the charge during ignition is caused by pseudo-grains ((
This is thought to be due to internal stress caused by the rapid evaporation of the water contained therein, and thermal shock caused by sudden exposure to high-temperature flames from temperatures close to room temperature to over 1000°C.

It is known that in a normal sintering process, a dry zone is formed below the extremely high temperature sintering reaction zone, and a wet zone (area where water condenses) is formed further below.

The sintering reaction zone gradually expands into a drying zone, but in the upper layer of the charge, there is almost no drying zone and the zone immediately becomes a sintering reaction zone, so the upper layer generally becomes The quality also tended to be poor.

The present invention solves these drawbacks, and if high-temperature dry gas is used to dry only the upper layer of the charge, the upper layer will be preheated, and the ignition furnace 6 will dry it from a low temperature close to room temperature. By doing so, the effect of the present invention is further enhanced, since it acts to alleviate the thermal shock given to the pseudo grains due to sudden exposure to a high-temperature flame of 1000° C. or higher.

Furthermore, according to the method of the present invention, it is possible to improve the air permeability in the wet zone generated during the sintering process, thereby making it possible to shorten the sintering time and reduce the proportion of coke mixed in the raw material.

Figure 2 shows the ventilation in the layer when the sintering material mixed with a moisture content of 6.0% is filled into the sintering machine for the first experiment so that the layer thickness is 400 mm, and the sintering reaction zone reaches a depth of 100 mm. This is an example of an experiment in which resistance and moisture in the layer were investigated and compared with conventional methods.

The dry air with temperatures of 250° C. and 100° C. used in this experiment was obtained from a cooler in the sintering process, and the dry air at room temperature was the air after passing through the dehumidification process.

The wind speed passing through the layer during this dry air blowing was 1.0 m/s
The dry air blowing time was set to 2 minutes with the aim of achieving EC.

As shown in this figure, when the sintering reaction zone advances to a depth of 100 mm from the upper layer, water concentration is observed in the layer below 100 mm from the reaction zone (we will call it the wet zone). There was a significant difference in resistance, and it was confirmed that the method of the present invention has extremely superior air permeability compared to the conventional method.

The humid zone is a region where water, which is contained in the exhaust gas sucked from the sintering reaction zone and the drying zone generated directly below it and passes through the layer during the sintering process, is concentrated by being cooled below the dew point.

Although the degree of water concentration is greatly affected by the temperature in the bed in this region, the water content often exceeds the appropriate value, and excess water is determined by the effective porosity of the packed bed made of pseudoparticles. This not only causes a decrease in the strength of the pseudo-particles, but also causes the pseudo-particles to collapse, and it is generally believed that the air permeability in this area is not good.

However, in the case of the method of the present invention, it was confirmed that air permeability was improved by changing the water concentration behavior.

In other words, the method of the present invention, in which the pseudo-granulated charge with a predetermined moisture content is dried with dry air before entering the ignition furnace, and then ignited and sintered, It has a very advantageous effect on the production and production rate, the degree of water concentration, and the concentration rate, and improves the air permeability in this area.

In the method of the present invention, if the process before the ignition furnace, that is, the gas supplied to the upper layer of the charge from the dry gas supply device 19, contains a large amount of moisture, the upper layer of the charge may be dried or moistened. Nor does it have the effect of reducing water concentration in the zone.

Or even if it were done, only a very small effect could be expected.

This dry air may be obtained by passing air through a dehumidifying device, but it is effective to use dry gas obtained from a cooler that air-cools the red-hot sintered ore during the sintering process.

High-temperature dry gas reaching up to 500°C can be obtained from here, so if you use this, you can not only dry the upper layer of the charge but also preheat it, which will affect the upper layer of the charge in the ignition furnace. It is extremely effective for the method of the present invention because it has a remarkable effect of mitigating thermal shock and also recovers the thermal energy possessed by the dry gas.

FIG. 3 shows an experimental example in which the temperature inside the charge layer was investigated when high-temperature dry gas was supplied above the charge 8 and air was taken in from below.

The dry gas used at this time was discharged from the cooler 16.
With dry gas at 00°C, the thickness of the charge was 400 mm, the wind speed passing through the bed was approximately 1 m/sec, and the distance was 30 w from the top of the charge.
A thermometer was inserted at a depth of 60 mm and 190 mm, and the temperature at each position was investigated by varying the dry gas supply time.

As a result, when the high-heat dry gas supply time was 2 minutes, the upper layer of the charge (30 mm depth from the surface) was 250°C.
The temperature reached 60mm.

There was no temperature change at each depth of 99 mm.

If the dry gas supply time is 4 minutes, the depth is 607n7.
It is found that it is possible to reach a high temperature of 250° C. or higher to a depth of 90 m71 by supplying 1 L for 6 minutes.

Next, the effect of the supply of high-temperature dry gas on the sintering time was investigated, and the results shown in FIG. 4 were obtained.

In other words, dry gas (dry gas obtained from a cooler) having a temperature of 300°C is supplied to the surface of the charge so that the air velocity U passing through the bed is 1 m/sec, and the air is sucked in from below, only in the upper layer of the charge. When igniting and sintering after drying and preheating, the sintering time can be rapidly shortened compared to the conventional method if the dry gas supply time is up to 2 minutes, but it may not be very effective if the dry gas supply time is 2 minutes or more. confirmed.

We also conducted an experiment to determine what happens to the intake amount of combustion air after ignition.

It is known that there is a positive correlation between the amount of combustion air supplied and the amount of sintered ore produced in sintering operations, and this experiment proved that the effect of the method of the present invention is extremely significant. .

That is, as shown in Fig. 5, according to the method of the present invention, high-temperature dry gas at 300°C is blown onto the top surface of the charge in front of the ignition furnace for 2 minutes at an air velocity of 1 m/sec through the bed, and then ignited and sintered. Go, wind box 9, 9...
When the suction air volume was measured at ..., it was found that u = 0.83 immediately after leaving the ignition furnace 6, and this state was maintained for about 6 minutes, after which it showed a tendency to increase gradually until sintering was completed, and 14 minutes after ignition. Completed sintering through all layers.

On the other hand, when using the conventional method, the air volume immediately after the ignition furnace is u = 0.6
After continuing this state for about 1 minute at U=0.75~0.
Slightly increase to 78, continue this state for about 6 minutes, then temporarily increase 1
Sintering was completed in 8 minutes.

Here, the differences between the method of the present invention and the conventional method are summarized as follows:
(2) There is a significant difference in the air volume immediately after exiting the ignition furnace, with the method of the present invention having a larger air volume by about 20 to 30%.

■ After ignition until the completion of sintering, the method of the present invention always has a higher air volume.

■ The sintering time is shorter in the method of the present invention.

There are three points. Such a remarkable difference is due to the effect of alleviating the thermal shock that is applied to the top surface of the charge during ignition, and the effect of improving air permeability in the wet zone formed below the sintering reaction zone.

In the method of the present invention, it is ideal to use dry gas that does not contain any moisture, but since it would be extremely expensive, a gas that contains some moisture may be used, but Unless dry gas is used, the effects of the present invention cannot be expected.

In addition, when using high-heat dry gas, the upper limit of the gas temperature is the temperature at which the solid fuel (coke powder) added to the charge does not burn, that is, the ignition temperature of the coke powder is approximately 50.
Since the temperature is 0°C, the temperature is preferably 500°C or lower, and it is advantageous to set the lower limit at room temperature or higher, preferably 100°C or higher, in order to dry the pseudo-grains in the upper layer of the charge in a short time.

As mentioned above, the method of the present invention has remarkable effects in terms of improving air permeability, shortening sintering time, and improving the quality of sintered ore. An experiment was conducted to reduce the proportion of fuel (coke powder) added to the charge while maintaining the quality of the resulting sintered ore at the conventional level.

An example of the results is shown in Table 1.

As shown in the above table, according to the method of the present invention, it is possible to first reduce the fuel consumption by 2 to 3 kg/T, S or more, and during this reduction, the amount obtained by the two-stage charging sintering method is It is comparable to the value given.

Furthermore, it was confirmed that the cold strength, such as the drop strength and tumbler strength, of the sintered ore would not be reduced, and on the contrary, a slight improvement could be expected.

In addition, in the present invention, it has been explained that dry gas obtained from the cooler of the sintering machine is used as a means for drying the surface layer of the charge, but it is also possible to obtain dry gas by burning coke oven gas etc. and use it alone. Alternatively, it is also possible to use it in combination with dry gas obtained from the cooler.

As described above, according to the method of the present invention, T/H can be improved by greatly shortening the sintering time, the blending ratio of fuel can be reduced, and even if such operation is performed, the sintering time will be significantly reduced. It has the remarkable effect of not reducing the quality of ore,
By utilizing the high temperature dry gas discharged from the cooler and released into the atmosphere, the present invention can be carried out very economically.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a sintering process showing an embodiment of the present invention;
FIG. 2 is a diagram showing changes in moisture content and ventilation resistance within the layer as the sintering reaction progresses. FIG. 3 is a diagram showing the relationship between the time for spraying high-temperature dry gas onto the top surface of the waste container and the temperature of the charge, and FIG. 4 is a diagram showing the relationship between the time for spraying and the sintering time. FIG. 5 is a diagram showing the amount of combustion air suctioned during sintering.

Claims (1)

[Claims] 1. In a sintered ore production method using a Dwight Lloyd sintering machine, the surface layer of the charge supplied onto a pallet is heated to room temperature to 2.
A sintering process characterized by supplying dry gas at 50°C and sucking air from below to dry only the surface layer of the charge to form a dry zone on the surface layer of the charge, and then igniting the dry zone. Concretion manufacturing method.