JPS5928829B2 - sintering machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in Dwight Lloyd sintering machines.

When producing sintered ore using a Dwight Lloyd sintering machine, conventionally the sintered raw material, which is made by mixing various raw materials and fuels and adding an appropriate amount of water to form pseudo-granules, is continuously charged onto a pallet and then passed through an ignition furnace. The pallet speed was controlled so that the sintering reaction zone was moved downward by igniting the upper layer and inhaling air from below, and the sintering reaction was completed in the entire layer near the ore discharge area.

However, the sintering reaction itself is not fully understood.
Many tasks, such as determining when sintering is complete, depend on the operator's patience, and there are still many gaps left 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 solid 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 blending ratio of the fuel.

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 produced sintered ore 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 sintered ore of high quality efficiently and at a low price.

Furthermore, not only the fuel but also the moisture contained in the raw material, the particle size of the raw material, the amount of air blown, etc. have important implications in the sintering process.

For example, regarding moisture, we tend to think that it is better to keep it as low as possible because if there is a lot of moisture, it will take up extra fuel, but the moisture added to the raw material indirectly plays a role in improving air permeability. In this sense, it is indeed essential.

What happens if you add a certain amount of moisture to a raw material consisting of powder and granules, mix it to create a sintered raw material, give it appropriate air permeability, and then dry and sinter the raw material to produce sintered ore? Although there have been some studies conducted on sintering, 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 Publication No. 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.

Furthermore, Belgian Patent No. 808,857 discloses that sintered raw materials (
A technique has been disclosed for drilling holes in the material (burden), but
In addition to the disadvantage that a special device for making holes must be provided, the number of holes is limited by such mechanical means, and it is extremely difficult to improve the air permeability over the entire surface of the charge and in all layers. It is.

In this way, the moisture contained in the charge is complicated, and the reality is that no practical and useful technology has emerged for improving air permeability. Problems remain.

The present invention focuses on improving air permeability during the sintering process, and has developed a device that solves this problem through repeated research based on a novel idea.

That is, the present invention provides the following features: (1) In a Dwight Lloyd type sintering machine, a drying preheating furnace for drying and preheating the upper layer of the charge is installed between the ore feeder and the ignition furnace, and an ore discharger is installed following the ignition furnace. A sintering machine characterized by having a hot air supply device installed on the side.

and (2) In the Dwight Lloyd type sintering machine, a drying preheating furnace for drying and preheating the upper layer of the charge is installed between the ore feeder and the ignition furnace, and a hot air supply device is installed on the ore discharge side following the ignition furnace. The gist of the present invention is a sintering machine characterized in that an air intake facility is provided independently below the drying preheating furnace.

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 is a conceptual diagram of a sintering process showing an embodiment of the present invention.

Before describing the present invention, the drying preheating furnace which is the main part of the present invention will be explained first.

As shown in FIG. 1, the dry preheating furnace according to the present invention continuously supplies sintering raw material 1 from a hopper 2 to a drum feeder 3 and onto a pallet 7 via a sloping plate 5, and rotates a sprocket 4 on the raw material supply side. At the very least, the charge (raw material) 8 on the pallet 7 is moved at low speed, and a plurality of wind boxes 9゜9...... are provided at the bottom of the duct 10.
Air is sucked in by a suction fan 12 through a waste gas dust collector 11, and the upper surface of the charge 8 is ignited in an ignition furnace 6, causing a sintering reaction over the entire layer of the charge 8 on the pallet as it reaches the ore discharge section. In a Dwight Lloyd type sintering machine that continuously produces sintered ore until it is finished, a dry preheating furnace 19 is installed between an ore feeder (hopper 2, drum feeder 3, sloping plate 5) and ignition furnace 6. , for continuously drying and preheating only the upper layer of the charge 8 before it enters the ignition furnace 6.

In conventional sintering machines, the charge placed on the pallet 7 is put into the ignition furnace 6, which is heated to over 1000°C, and is suddenly exposed to a high-temperature flame, causing the temperature to rise and ignite extremely rapidly. The surface of the charge is subjected to a large thermal shock, so by adding several percent of water to various raw materials and fuels made of powder and granules, the pseudo-granules on the surface of the charge, which have improved air permeability, are destroyed. The air permeability was severely impaired.

Then, the sintered completed layer and the reaction surface formed on the surface layer grow and move downward, and air continues to be sucked in from the lower wind box until the sintering reaction finishes over the entire layer near the ore discharge area, so in the ignition furnace, The resulting deterioration in air permeability in the surface layer continued to affect the material until the end of sintering.

The destruction of the pseudo-grains in the surface layer of the charge during ignition is thought to be due to the internal stress associated with the rapid evaporation of the water contained in the pseudo-grains, and the thermal shock caused by the sudden exposure to high-temperature flame from a temperature close to room temperature.

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

Since the reaction zone is sucked in from below, it progresses as if it is gradually expanding into a drying zone, but in the upper layer of the charge, there is almost no drying zone and the reaction zone immediately becomes a sintering reaction zone. In general, the quality also tended to be poor.

The dry preheating furnace according to the present invention can solve these drawbacks, and since it not only dries the upper layer of the charge but also preheats it, the temperature in the ignition furnace 6 can rapidly rise from near room temperature to over 1000°C. It has the effect of alleviating the thermal shock given to the pseudo grains due to high heat.

In the drying preheating furnace 19, high-heat dry gas may be generated by burning fuel such as coke oven gas, but the high-heat dry gas generated when red-hot sintered ore is air-cooled is generated from the cooler 16 in the sintering process. The gas may be recovered and introduced, or the high-temperature dry gas discharged from the ore discharge side of the wind boxes 9, 9, . . . may be recovered and used.

Next, an experiment was conducted in which high-temperature dry gas was supplied from a drying preheating furnace and air was taken in from below to dry and preheat the upper layer of the charge before ignition, and then ignited and sintered.

The results are shown in FIG.

In addition, in the figure, the method shown as the present invention shows the case where the dry preheating furnace according to the present invention is used, and the case shown as the conventional method shows the case where the dry preheating furnace is not used.

Figure 2 shows that sintering raw materials mixed with a moisture content of 6.0% are filled into an experimental sintering machine so that the layer thickness is 400 mm, and the sintering reaction zone is 1.
This is an example of an experiment conducted on the ventilation resistance and moisture in the layer at the time when the depth of 0.00 mm was reached, and the high-temperature dry gas was recovered from the cooler in the sintering process at 100 °C and 250 °C.
The drying preheating time was set to 2 minutes, with the target air velocity passing through the layer at 1.0 m/sec.

As shown in this figure, when the sintering reaction zone advances to a depth of 100 cages from the upper layer, water concentration is observed in the layer below 100 mm from the reaction zone (hereinafter referred to as the wet zone). There was a significant difference in ventilation resistance between the case using the drying preheating oven according to the present invention and the conventional method, and it was confirmed that the case using the drying preheating oven had extremely superior air permeability compared to the conventional method. .

The wet zone is a region where the moisture contained in the suction exhaust gas from the sintering reaction zone and the dry zone generated directly below it during the sintering process and passing through the layer is cooled to below the dew point and concentrated.The degree of moisture concentration is in this region. Although the moisture content is greatly affected by the temperature inside the bed, the moisture content often exceeds the appropriate value. Excess moisture not only reduces the effective porosity of the packed bed composed of pseudo particles, but also It was generally believed that this region had poor ventilation, as it would induce a decrease in strength, which could cause the pseudoparticles to collapse.

However, when using the drying preheating furnace according to the present invention, the air permeability can be improved by changing the moisture concentration behavior.

That is, before the pseudo-granulated charge with a predetermined moisture content enters the ignition furnace, only the upper layer of the charge is dried and preheated with high-temperature dry gas in a dry preheating furnace, and then ignited and sintered. This has a very advantageous effect on the formation and rate of formation of a wet zone, the degree of water concentration, and the rate of concentration, and improves the air permeability in this area.

Next, the effect on the sintering time of drying and preheating the upper layer of the charge in the drying preheating furnace according to the present invention was investigated, and the results shown in FIG. 3 were obtained.

At this time, in the drying preheating oven, the temperature obtained from the cooler 16 is 300°C.
A wind box 9', which is provided independently for exclusive use of the drying preheating furnace 19, supplies high-heat dry gas to the top surface of the charge, and from below,
Air was taken in from 9' through the suction fan 12', the dust remover 11', the flow rate adjustment valve 18, and the duct 10' so that the air velocity passing through the bed was U\In/sec.

As shown in the figure, when the drying preheating furnace is operated to supply high-temperature dry gas from the drying preheating furnace 19 for 2 minutes, the drying temperature increases rapidly compared to the conventional method (zero hot air supply time in the drying preheating furnace). It was confirmed that it has the effect of shortening the setting time.

We also conducted an experiment to see what happens to the suction amount of heating 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 demonstrated that the effect of the device of the present invention is extremely significant. Ta.

That is, as shown in FIG. 4, high-temperature dry gas at 300° C. is supplied to the top surface of the charge from the drying preheating furnace of the apparatus of the present invention,
By sucking air from wind boxes 9' and 9' installed independently below this drying preheating furnace, the air velocity U\
After drying and preheating the upper layer of the charge for 2 minutes at 1 m/sec, it is ignited and sintered, and the wind box 9/, 9/...
When the suction air volume was measured at ..., it became u = 0.83 immediately after leaving the ignition furnace, and this state was maintained for about 6 minutes, and then it tended 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.
After continuing this state for about 1 minute at 68, u=0.75~0
．． Slightly increase to 78 After continuing this state for about 6 minutes, temporarily increase 1
Sintering was completed in 8 minutes.

Here, to summarize the differences between the case using the drying preheating furnace according to the present invention and the conventional method, there is a significant difference in the suction air volume immediately after exiting the zero ignition furnace. There are many.

■The air volume is higher if the drying preheating furnace is used continuously after ignition until the completion of sintering.

■The sintering time is shorter when using a dry preheating furnace.

Such a remarkable difference is due to the relaxation of the thermal shock that the upper surface of the charge receives during ignition and the improvement in air permeability in the wet zone that is formed below the sintering reaction zone.
This is the effect of

In addition, it is desirable that the upper limit temperature of the high-temperature dry gas be below the temperature that does not cause the coke powder added to the charge to burn, and the moisture contained in the dry gas must be below the internal humidity of the sintering plant. , the effect cannot be expected.

The present invention installs the above-mentioned drying preheating furnace and also includes a heat retention furnace following the ignition furnace, which eliminates the disadvantages of installing a heat retention furnace alone and lengthens the sintering time. The purpose of the present invention is to provide a sintering machine that can improve the quality of sintered ore and reduce the coke consumption rate without causing any vibration.

As mentioned above, the drying preheating furnace according to the present invention is effective in improving the air permeability in the charge layer, shortening the sintering time, and improving the quality of sintered ore. If a hot air supply device 20 is installed on the ore side and hot air is supplied from there, significant effects can be expected from the viewpoints of improving the quality of the sintered ore and saving energy.

The technique of improving the quality of sintered ore by providing a heat retention furnace on the ore discharge side of the ignition furnace and supplying high-temperature gas therefrom in the sintering process is already well known.

However, this technology has the disadvantage of prolonging the sintering time, which can be a huge disadvantage in the sintering process. When it comes to the conditions for thermal furnaces, it is not unreasonable to come up with a unified opinion.

In the present invention, the effect of the dry preheating furnace 19 installed before the ignition furnace 6 is to improve the air permeability within the layer and significantly shorten the sintering time as described above. By installing the hot air supply device 20 on the ore discharge side of the ignition furnace 6 in combination with this, the above-mentioned disadvantages can be largely eliminated, and it is possible to take advantage of the advantages of obtaining high-quality sintered ore.

Note that it is effective to supply the hot air supply device 20 with high-temperature air discharged from the cooler 16.

The present inventors took advantage of the remarkable effects of the device of the present invention,
An experiment was conducted to reduce the ratio of fuel (coke powder) added to the charge while maintaining the sintering time and quality of the resulting sintered ore at conventional levels.

The results are shown in Table 1.

As shown in the table above, by using the device 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 two-stage charging sintering method is used. This value is comparable to that obtained with .

Furthermore, it was confirmed that the cold strength, such as the drop strength and tumbler strength, of the sintered ore was not reduced, but rather could be expected to be slightly improved.

Note that it is effective to use the drying preheating furnace 19, the ignition furnace 6, and the hot air supply device 20 according to the present invention as one long furnace, with the front stage as the drying preheating furnace, the middle stage as the ignition furnace, and the rear stage as the hot air supply device. Furthermore, since the hot air supply device is a device corresponding to a conventional heat retention furnace, it is effective to improve the heat retention effect in this furnace by combusting coke oven gas, etc., as in the prior art.

Furthermore, in the drying preheating oven, coke oven gas or the like may be combusted in order to obtain hot air without departing from the technical idea of the present invention, or coke oven gas or the like may be combusted auxiliary to adjust the temperature of the hot air. is possible.

As described above, according to the present invention, it is possible to improve T/H by significantly shortening the sintering time, it is possible to reduce the blending ratio of fuel, and even if such an operation is performed, the sintering time is significantly reduced. It has the remarkable effect of not reducing the quality of ore, and has the effect that the present invention can be carried out extremely economically by using the high-temperature dry gas discharged from the cooler and released into the atmosphere until now. It is something.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of a sintering process showing an embodiment of the present invention. Figure 2 is a diagram showing intralayer moisture and airflow resistance during the sintering process. FIG. 3 is a diagram illustrating the relationship between the time for blowing high-temperature dry gas onto the top surface of the charge before the ignition furnace and the sintering time. FIG. 4 is a diagram illustrating the relationship between the elapsed time after ignition and the wind speed passing through the raw material layer.

Claims (1)

[Claims] 1. In a Dwight Lloyd type sintering machine, a drying preheating furnace for drying and preheating the upper layer of the charge is installed between the ore feeder and the ignition furnace, and a drying and preheating furnace for drying and preheating the upper layer of the charge is installed following the ignition furnace on the ore discharge side. A sintering machine characterized by being equipped with a hot air supply device. 2. In the Dwight Lloyd type sintering machine, a dry preheating furnace for drying and preheating the upper layer of the charge is installed between the ore feeder and the ignition furnace, and a hot air supply device is installed on the ore discharge side following the ignition furnace, A sintering machine characterized in that an air intake facility is independently provided below the drying preheating furnace.