JP3322148B2 - Sinter production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a sintered ore, and more particularly, to a method for producing a sintered ore in which the amount of water added during granulation is controlled to an appropriate range.

[0002]

_2. Description of the Related Art Sintering raw materials are composed of several types of iron ore, limestone as a CaO source, serpentine powder as a source of SiO ₂ and MgO, coke breeze as a fuel, and ore return. These raw materials are cut out from each raw material tank by a fixed amount, and are sequentially placed on a conveyor belt conveyor so that all the raw materials join at a position on the exit side of the most downstream raw material tank. At this time, since the state of each raw material remains in an uneven state laminated on a belt conveyor, it cannot be directly supplied to the sintering machine, and a mixing operation for homogenization is required in advance. Become.

Further, since the sintering raw material is usually a powder having a particle size of 5 mm or less, and since coarse particles and fine powder having a large difference in particle size are mixed, voids between the raw material particles are small. It is difficult to form an air flow path for burning the coke breeze. In order to eliminate this state, it is necessary to perform a granulation operation in which a fine powder material is attached around a relatively coarse material to produce pseudo particles. Due to the formation of the pseudo particles, the difference between the particle diameters of the raw materials is reduced, so that the voids required for ventilation can be secured.

At present, in a raw material processing line of a sintering machine, generally, the above-mentioned mixing operation and granulation operation are generally performed simultaneously with a cylindrical drum type mixer (hereinafter, simply referred to as a drum mixer). The raw materials after the mixing are uniformly mixed by a drum mixer, and water is added, so that granulation proceeds.

[0005] After the mixing and granulation, the wet raw material is charged into a sintering machine, ignited on the surface, and then coke is burned by the sucked air. Due to the resulting heat, iron ore,
A so-called sintering reaction in which limestone and serpentine powder are welded to each other proceeds from the upper layer to the lower layer. As the sintering reaction zone progresses, the underlying wet material zone gradually disappears. On the other hand, on the other hand, a sintering completed zone called a sinter cake is newly formed in the upper layer of the sintering reaction zone and gradually increases in thickness.

[0006] As the sintering further proceeds, the wet raw material zone and the sintering reaction zone completely disappear, leaving only the sinter cake. At this point, the sintering is completed. The sinter cake discharged from the sintering machine is crushed and sized to a size suitable for charging the blast furnace, separated into products and fine-grained ore, and the returned ore is used again as a raw material for sintering.

As described above, in the course of sintering, three types of zones appear, of which the wet zone and the sinter cake disappear or are formed as a result of the progress of the sintering reaction zone. The productivity of the sintering machine is uniquely determined by the speed of the sintering reaction zone.

[0008] In the sintering reaction zone, a combustion reaction of coke and an ore welding utilizing the combustion heat occur. The reaction is preceded by a coke combustion reaction, which determines the rate of progress of the sintering reaction zone.

In a sintering machine, coke for welding ore to the raw material is previously blended in the raw material processing line, so that the combustion rate is determined not by the coke supply rate but by the air supply rate. . Further, since the air is supplied by the suction exhaust fan, the air supply speed is determined by the ventilation resistance obtained by adding the resistances of the three zones of the sintering completion zone, the sintering reaction zone and the wet raw material zone to be aerated.
Among these three zones, the zone having the highest airflow resistance is the wet raw material zone. To promote the combustion of coke, it is advisable to improve the air permeability of this zone. Therefore, as described above, promotion of formation of pseudo particles by a granulation operation is indispensable for improving the permeability of the wet raw material zone.

[0010] The formation of the pseudo-particles also contributes to the improvement of the product yield, and consequently has the effect of improving the productivity of the sintering machine. In other words, this is because the supply of air is made uniform by the formation of pseudo particles, the combustion efficiency of coke is increased, and the welding of ores is strengthened.

Conventionally, it has been known that the formation of pseudo-particles as a raw material in a granulation operation is strongly affected by the appropriateness of the amount of water serving as a binder. In other words, pseudo-particles are particles having relatively coarse-grained raw material as a nucleus and having other fine powder raw material suction-adhered to the surface thereof by the capillary force of water. It is necessary to add an adequate amount of water without shortage.

On the other hand, in an actual sintering machine, the raw materials used have different moisture absorption rates for each type, and the water contributing to granulation fluctuates. Actually, segregation occurs in the raw material storage tank, and when blended, the particle size distribution and the water content vary. Further, the temperature of the remineralization added to the raw material before granulation is not constant, and the amount of water evaporation thereby changes, resulting in a change in the moisture content of the raw material to be blended.

[0013] Under the situation where the properties of each raw material change every moment, the water content of the blended raw material also fluctuates similarly, and accordingly, the water addition control for maximizing the formation of the pseudo-particles accordingly. Technology is required.

Many methods have been proposed to achieve this. For example, Japanese Unexamined Patent Publication (Kokai) No. 59-222538 discloses that the pseudo particle size composition is theoretically calculated from the material properties such as the particle size distribution and water absorption of each brand of the compounded raw material and the compounding ratio thereof, and the raw material mixing conditions JP-A-61-250119 discloses a method for predicting the firing rate using information on the porosity of the packed bed, the height of the packed bed, and the suction pressure of the exhaust fan in addition to the properties of the blended raw materials. A method for determining the raw material mixing conditions and the sintering operation conditions is disclosed. However, these methods merely set the operating conditions by predicting the air permeability from the calculated pseudo particle distribution, and set the maximum air permeability to substantially improve the production rate and the optimum air permeability for that. The raw material moisture value has not yet been directly controlled.

As a solution to the above-mentioned problem, for example,
As disclosed in JP-A-34120, the amount of water added in a drum mixer on a raw material processing line of an actual machine is changed stepwise, and the air permeability of a raw material packed layer is continuously measured on a sintering machine. Thus, a method for determining the optimum moisture content has been proposed. However, this method is excellent in directly evaluating the air permeability on-line, but since this information alone is used to adjust the amount of water added, the water content may be out of the appropriate value and may be too low or too high. . As a result, the air permeability fluctuates rapidly, and the sintering reaction is disturbed, and there is a risk of discharging a large amount of unsintered defective products from the sintering machine, which is not a preferable method.

Further, in JP-A-5-195089 and JP-A-5-222463, a part of the raw material after granulation is sampled, divided and further granulated with different moistures. A method is disclosed in which sintering is actually performed in a small test pan, and from these results, appropriate operating conditions for improving productivity and yield are evaluated. This method evaluates the appropriate amount of water added off-line, so there is little danger of discharging a large amount of defective products with a sintering machine, but the measurement requires a lot of man-hours and can be obtained within a certain period of time. Data is low and is not effective as an online control tool.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to cope with a change in the water content of a raw material in a sintering machine which is constantly changing.
The amount of water added for promoting granulation in the drum mixer is appropriately changed so that the raw material permeability is maximized, and the sinter ore that enables the productivity of the sintering machine to be constantly maintained at a high level It is to provide a manufacturing method.

[0018]

The gist of the present invention resides in a method for producing a sintered ore in which the amount of added water is controlled by a drum mixer of a sintering machine described below.

A fixed amount of raw material is sampled at the outlet side of the drum mixer in the raw material processing line of the sintering machine, and the raw material is used for an off-line test drum mixer (this mixer may be a small one. A mixer)
The optimum amount of water added is determined by judging the rolling state of the raw material in the step (1), and the amount of water added to the drum mixer in the raw material processing line of the sintering machine is controlled based on the result. The method of producing condensate.

Since the above-mentioned small mixer is used for testing, it is desirable that the size of the mixer is as small as possible and that the material rolling state in the drum mixer in the material processing line of the sintering machine can be reproduced. For example, a minimum of 0.3
m and a length of 0.5 m, and if the rotational peripheral speed and the cross-sectional space factor of the raw material match those of the drum mixer of the raw material processing line of the sintering machine, the rolling state of the raw material can be almost reproduced.

The amount of raw material to be collected is determined in accordance with the cross-sectional space factor, but the absolute amount is preferably 20 kg or more from the viewpoint of representing the properties of the raw material.

The humidification rate of the small mixer is desirably 0.2 to 0.5% by weight / minute in terms of water content. 0.
If it is less than 2% by weight / minute, it takes time for the rolling state of the raw material to change, and it takes too much time for the measurement.
If the rate exceeds / min, the rolling state of the raw material is measured without uniformly dispersing the added water, and accurate evaluation cannot be performed.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The most significant feature of the method of the present invention is as follows.
It is to judge the appropriateness of the amount of water to be added from the rolling state of the raw material in the small mixer.

Hereinafter, the method of the present invention will be specifically described.

As described above, the granulation mechanism of the sintering raw material is as follows. First, moisture is absorbed into the internal pores of the raw material, and then excess water becomes a binder on the ore surface where the water content is saturated. Other ores are adsorbed by the water's capillary adsorption power, and aggregation proceeds to form pseudo particles. If an appropriate amount of water is added, a number of pseudo particles grow simultaneously and in parallel, voids are formed between these pseudo particles, through which air for burning coke passes, and the sintering reaction proceeds smoothly. It creates a situation to do.

On the other hand, if the amount of water to be added is too small, the granulation does not proceed and the fine powder raw material remains in the gap between the coarse raw materials. On the other hand, if too much water is added, once the raw material is normally granulated and the fine powder raw material adheres to the surface of the coarse-grain raw material, the fine powder raw material will The raw material is separated from the coarse raw material, suspended in water, becomes muddy, and the whole raw material falls into a sticky state. As a result, when the moisture added to the sintering raw material is insufficient, the remaining fine powder raw material impedes the ventilation of the wet raw material zone, and when the added moisture is excessive, the fine powder raw material is The suspended muddy layer hinders aeration of the wet feed zone, and consequently hinders the progress of the sintering reaction zone.

As described above, the quality of granulation can be usually evaluated by filling the raw material after the completion of the granulation operation into a certain container, aerating the air, and measuring the aeration characteristics. it can. However, it takes too much time to perform such an operation for each evaluation, which is not suitable for online control. In order to realize online control, it is necessary to reduce the evaluation time of granulation.

By the way, the rolling state of the sintering raw material in the drum mixer fluctuates depending on the moisture content, and as a result, the progress of the granulation of the raw material changes, resulting in a difference in the formation of pseudo particles.

The basic idea of the present invention is to utilize this phenomenon to grasp the rolling state of the raw material in the drum mixer, to evaluate the degree of granulation (appropriateness), and to add based on the result. The purpose is to control the water content to an appropriate value. However, controlling the rolling state directly by changing the added water in the drum mixer on the actual machine line is because the sintering reaction becomes unstable due to fluctuations in the gas permeability of the raw material when it is outside the appropriate range, and It is not a good idea because mass production of creatures is possible. Therefore, in order to avoid such a state, a device for observing the rolling state offline is provided, and the optimum amount of added water is grasped here, and the result is used for controlling the added water in the drum mixer on the actual machine line. Reflecting is a more substantial and effective method of controlling moisture.

FIG. 1 shows an example of an apparatus for measuring the rolling state of a raw material. The apparatus comprises an ITV camera 1 for image analysis of the rolling state of the sintering raw material during hydration granulation, an offline small-sized mixer 2 for confirming the rolling state of the raw material, and an apparatus for adding water to the raw material. It is composed of a water addition pipe 3.

A method for ascertaining the optimum amount of water added to the sintering raw material using this apparatus will be described below.

A part of the raw material (see Formulation 1 in Table 1) used in the actual machine was transferred to a small mixer 2 (0.4 m in diameter and 1.0 m in length) in the same cross-sectional space factor as the actual drum mixer. 50 kg is charged so that

[0033]

[Table 1]

The small mixer 2 into which the raw materials are charged is placed in a horizontal state, and then water is added in a spray form from the water addition pipe 3 while rotating the mixer at 25 rpm to perform granulation. The pipe is provided with a plurality of pores, from which water is jetted.

Since the amount of water added per unit time by the water addition pipe is set to be constant (250 CC / min), the total amount of water addition is uniquely determined from the water addition time.

While the granulation is being performed, the rolling state of the sintering raw material is imaged by the ITV camera 1, and an image analysis of the state change is performed.

The object of analysis is the rolling shape of the whole raw material and the scraping angle θ (the angle of a sector formed by connecting both ends of the arc on the inner surface of the small mixer with which the raw material is in contact and the center of the small mixer, 2).

First, the rolling shape of the whole raw material is shown. In the small mixer, the raw material shows three kinds of movements according to the amount of added water, and the rolling shape of the raw material differs in each state. FIG. 2 is a sectional view showing this state.

(A) shows the stage of water shortage in which the added water is absorbed into the internal pores of the raw material 4. The raw material has a lens-like shape and is entirely together at the bottom of the small mixer 2. Glide left and right. This is a state in which granulation has hardly progressed.

When the amount of added water is further increased, the water starts to be used for agglomeration of the raw materials, and the raw materials are scraped up in the rotating direction of the small mixer to start rolling and granulation to proceed. Is done. In this state (B), the entire raw material has a tom-shaped shape. As the addition of water is continued, the raw material scraping becomes more and more active, and the granulation further progresses accordingly.

However, when the water content becomes excessive, the raw material starts to adhere to the small mixer and the rolling of the raw material decreases,
Eventually, the whole raw material sticks to the small mixer. At this time, the shape of the entire raw material is a band shape shown in (C).

As described above, the shape change of the entire raw material accompanying the progress of granulation shows the same tendency irrespective of the type and particle size of the raw material.

Next, the raw material scraping angle θ will be described with reference to FIG. In the state of (A) with insufficient water, the raw material scraping angle θ is as small as less than 60 degrees. As the raw material rolls uniformly, the raw material scraping angle θ increases,
In the state of the moisture appropriate region (B), the angle is 60 to 120 degrees. The state (C) in which θ exceeds 120 degrees is a state in which the water content is excessive and the entire raw material is tackified.

In the pseudo particle formation, in the state of (B), after the core particles are lifted together with the rotation of the small mixer,
It progresses only when it falls while rolling on the slope from the top.
Therefore, even in the same state (B), the longer the rolling distance on the slope, that is, the larger the raw material scraping angle, the more advantageous for granulation. However, the absolute value of the raw material scraping angle θ in each state shown here is an example, and in actuality, this value differs depending on the type, the particle size, and the like of the raw material. Therefore, it is not appropriate to judge the quality of the raw material granulation based only on the raw material scraping angle θ. It is necessary to determine the optimum amount of added water in consideration of the above-mentioned grasp of the rolling shape of the entire raw material.

From the above, the criterion for judging the optimum amount of water to be added by the raw material image analysis is as follows.

The rolling shape of the entire raw material is as shown in FIG. 2 (B).

In the state shown in FIG. 2B, the raw material scraping angle θ must be the maximum.

Next, for the raw materials of Formulation 1 shown in Table 1, the air permeability of the raw materials in each state was examined. The air permeability was evaluated by the following JPU index.

Air permeability (JPU index) = (air volume / suction area) × (layer thickness / suction negative pressure) ^{0.6 The} results are shown in FIG. The larger the JPU index, the better the air permeability.

In the region of insufficient moisture and excess moisture, the extreme
The JPU index is maintained at a high level in an appropriate moisture range where the index is low and the raw material scraping angle is 60 to 120 degrees. JP
The maximum U index is the point where the moisture content is highest in the moisture appropriate region. Here, the raw material scraping angle θ is also maximum.

Similarly, the raw materials of Formulations 2 and 3 shown in Table 1 were examined. The results are summarized in Table 2. It is clear that the moisture value at which the rolling state of the raw material is good depends on the type of the raw material used. Therefore, in a sintering machine, it is necessary to appropriately control the addition of water with the change of the raw material composition.

[0052]

[Table 2]

When the types of raw materials are different, the factors that affect the promotion of granulation are fluctuating factors such as water wettability,
Water absorption, attached moisture, particle size distribution, etc. Further, it is known that in a sintering machine, even if the raw materials are mixed in the same manner, the attached moisture and the particle size distribution among the above-mentioned materials fluctuate. Therefore, proper control of water addition in the drum mixer in the raw material processing line is required not only when the raw material composition is changed but also when the same raw material is continuously used.

The determination of the quality of the rolling state used in the method of the present invention can be as short as about 30 minutes from the raw material collection to the end of the measurement. Therefore, the method of the present invention is not only at the time of the change of the raw material mixing ratio, but also sufficiently follows the change of the raw material particle size and the water content in the same raw material which fluctuates in units of tens of minutes, and the water addition amount online It is an effective way to control.

As described above, information on the optimum amount of water added is
If the control is reflected in the drum mixer in the raw material processing line of the sintering machine, the productivity of the sintering machine and the product yield can be constantly maintained at a high level.

[0056]

EXAMPLES In order to confirm the effects, the method of the present invention was applied to an actual sintering machine, and the effectiveness was evaluated in terms of the production rate and the product yield of sinter.

FIG. 4 is a flow chart of adding an optimum amount of water in a sintering machine, and FIG. 5 shows a method of collecting raw materials to be supplied to a small mixer.

The thickness of the raw material layer on the sintering machine and the suction negative pressure of the exhaust fan were kept constant.

(Example 1) Using the same kind of raw material (formulation 1 shown in Table 1), operation was carried out on an actual machine, and the effect of the method of the present invention was confirmed by comparing the method of the present invention with the conventional method. .

After each sintering raw material to be used is cut out from the raw material tank 5, a primary mixer (high-speed stirring mixer) 6
And a secondary mixer (drum mixer)
At 7, addition of water and granulation were performed, and the mixture was conveyed to a sintering machine. In this embodiment, the addition of water is performed by the secondary mixer. However, the addition of water by the primary mixer or both may be performed simultaneously.

In this step, a part of the raw material was sampled at the outlet of the secondary mixer 7 by the raw material sampler 8 shown in FIG. 5, and the erect small mixer 2 (0.4 m in diameter, 1.0 m in length) Was charged inside. The weight of the raw material is measured by a load cell installed on the support of the small mixer, and 50 kg
Was collected. At this time, the cross-sectional space factor of the raw material in the small mixer was 10% as in the secondary mixer.

After charging the raw material 4, the small mixer 2 was placed in a horizontal state, rotated at a speed of 25 revolutions / minute, and simultaneously, water addition was started at a constant rate of 250 CC / min. From the relationship between the raw material collection amount and the water addition rate, the rate of increase in the water content of the raw material was 0.5% by weight / minute, and the water content was increased while the water was well dispersed. This operation was continued until the rolling shape of the entire raw material reached the state shown in FIG.

An image of this series of steps is taken by an ITV camera,
The rolling shape and the change of the scraping angle of the whole raw material were image-analyzed by the process computer 9 and taken in as data.

From the image analysis data, the point in time when the rolling shape of the entire raw material was in the state shown in FIG. 2B and the scraping angle was the maximum was determined. Further, the amount of added water at this time was integrated based on the addition rate of water and the addition time, and was taken as an appropriate added water value.
The result was fed back to the secondary mixer 7 of the actual machine via the process computer 9 to control the amount of water added.

On the other hand, as a comparative example, a required amount of water calculated from a target water value set based on experience is added to the secondary mixer 7 in a fixed amount without using the small mixer 2 for determining the added water. Granulation was performed by the method described above.

First, the operation without using the small mixer for determining the added water, which is a comparative example, was performed for 10 hours, and then the operation of the present invention was performed for 10 hours using the information on the optimum amount of added water obtained by the small mixer. Was done.

As shown in FIG. 6, by applying the method of the present invention, the raw material is controlled to the optimum moisture content for maximizing the air permeability, and the sinter production rate and the product yield are maintained at a high level. It is clear that it stabilizes at the same time.

Example 2 The effect of the method of the present invention when the composition of the raw materials was changed was confirmed.

First, using the raw material of Formulation 2 shown in Table 1,
Thereafter, the operation was switched to the raw material of Formulation 3. Other conditions were the same as those in Example 1.

As shown in FIG. 7, by applying the method of the present invention, the water content was controlled to an appropriate value according to the raw material composition, and the sinter production rate and product yield were improved and stabilized. Is evident.

[0071]

According to the present invention, the optimum amount of added water is determined by measuring the rolling state of the raw material with a small offline mixer, and based on the result, the amount of added water in the drum mixer in the raw material processing line of the sintering machine is determined. According to the controlling method of the present invention, the gas permeability of the raw material is improved, and the productivity of sinter, the product productivity and the product yield are improved and stabilized.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a raw material rolling state measuring device of the present invention.

FIG. 2 is a cross-sectional view showing a rolling state of raw materials in the small mixer device of the present invention.

FIG. 3 is a graph showing the relationship between the amount of added water and air permeability (JPU index).

FIG. 4 is a control flow chart for adding an optimum amount of water.

FIG. 5 is a schematic view of an apparatus for collecting a sintering raw material.

FIG. 6 is a diagram showing an effect of one example in which the present invention is applied to a sintering machine (actual machine).

FIG. 7 is a diagram showing an effect of another example in which the present invention is applied to a sintering machine (actual machine).

[Brief description of reference numerals]

 1: ITV camera 2: Small drum mixer 3: Water addition pipe 4: Raw material 5: Raw material tank 6: Primary mixer 7: Secondary mixer 8: Raw material sampler 9: Process computer

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-55-164038 (JP, A) JP-A-5-195089 (JP, A) JP-A-5-222463 (JP, A) JP-A-5-222463 279756 (JP, A) JP-A-6-327960 (JP, A) JP-A-8-134555 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C22B 1/16

Claims (1)

(57) [Claims] 1. A fixed amount of raw material is sampled at the outlet side of a drum mixer in a raw material processing line of a sintering machine, and the raw material is rolled while adding water using an off-line test drum mixer using the raw material. The production of sintered ore characterized by judging the quality and determining the optimum amount of water to be added for promoting granulation, and controlling the amount of water to be added in a drum mixer in a raw material processing line of a sintering machine based on the result. Method.