JPH07173546A - Production of sintered ore - Google Patents

Abstract

PURPOSE:To stably maintain the sinterability of the thickness direction of a raw material packed bed and enhance the strength of sintered ore by compounding returns at a specific ratio into the specific depth region from the surface of the packed bed prior to burning and sintering of the packed bed. CONSTITUTION:The compounded raw materials are supplied from an ore feed hopper 2 to a moving type pallet 1 of a Dwight-Lloyd sintering machine to form the raw material packed bed (g). The raw materials fed out of a hopper 3 for increased compounding of returns or mill scale are fed by a belt conveyor 4 to a simple mixer 5. The returns or mill scale is stored in a subhopper 2b. The raw materials from a main hopper 2a and sub-hopper 2b of the supply hopper 1 are supplied onto the pallet 1 with a time lag. As a result, the returns are compounded at a ratio of 25 to 95wt.% into the compounded raw material region of 50 to 150mm from the surface of the packed bed (g). The ratio is specified to 1 to 15% in the case of the mill scale. The sintered ore is produced by burning and sintering the packed bed (g).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to stably obtain a high quality sinter when producing a sinter which is a blast furnace charging raw material by using a Dwightroid type sintering machine. Is.

[0002]

2. Description of the Related Art Conventionally, a Dwightroid type sintering machine has been used for producing a sintered ore as a raw material for charging a blast furnace.

This sintering machine is of a type equipped with an endless annular belt (actually a pallet is used) (see FIG. 4), and the following various raw materials are used.

(A) powdered ore (generally having a particle size of 10 mm or less), (b) return ore (particle size of 5 mm or less generated in the process of crushing and classifying to a particle size suitable for use in a blast furnace) Sinter, compounding ratio is about 12-25%), (c) Sintered powder coke (with an average particle size of 1.0-2.0 mm),

As a sintering auxiliary material, (d) limestone (generally having a particle size of 4 mm or less is used, and calcium having a melting temperature of about 1205 ° C. is reacted with Fe ₂ O ₃ in the powdery ore. Form ferrite (CaO · Fe ₂ O ₃ + liquid phase)),
(e) Dolomite, serpentine, etc. (generally having a particle size of 3 mm or less is used as a slag-forming agent or for adjusting basicity),

In the production of sinter, the above-mentioned various raw materials are each cut out at a ratio according to the operating conditions,
After adding 7% of water, it is pseudo-granulated by a drum mixer, and then fed through a feed hopper, a drum feeder and a chute to a pallet of a circulation type.

The raw material packed bed on the pallet is ignited by an ignition burner in the upper layer portion thereof, while air is sucked by a suction blower arranged at the lower part of the pallet from the upper part to the lower part in the thickness direction of the packed bed. , Combustion zone, combustion melting zone, dry zone, and wet material zone are formed,
As the pallet moves, the above combustion zone moves from the upper part to the lower part of the packed bed to produce a sintered cake (lump).

[0008]

By the way, the production of sinter using the above-mentioned conventional method, that is, the coke powder in the blended raw material is burned while sucking air from the upper side to the lower side of the raw material packed bed. In the production of sinter ore in which the progress of sintering is promoted, there were the following problems.

The raw material filling layer formed on the pallet is
Since the packing density is low and the air permeability is good in the upper layer part, the cold air immediately above the packing layer is sucked into the blower as it is during the sintering, so that the temperature rise cannot be expected and the cooling is performed quickly. Therefore, in this region, the melting rate is low and a sintered cake having a high porosity can be obtained, so that the strength is low and the yield is unavoidable.

Further, in the middle layer portion of the raw material filling layer, the packing density is increased due to the load of the upper layer portion, and at the same time, since high temperature air passes during the sintering of the raw material, it is preheated and the sintering progresses. A strong sinter cake is produced.

Further, in the lower layer portion of the raw material-filled layer, the suction air from the blower is sufficiently preheated and heated in the filled layer to cause excessive heat, which causes excess melt and impairs air permeability and sinter rate. Decrease and hinder productivity.

As a method of solving the above-mentioned conventional problems, when charging the raw materials to be mixed onto a pallet, a plurality of bar members are arranged such that the interval between the upper part and the lower part thereof is larger than those of the bar members. A sintering raw material was supplied onto a sintering pallet through a sieve surface formed by a bar material, and fine particles were segregated in the upper layer portion of the raw material filling layer and coarse particles were segregated in the lower layer portion. The method disclosed in Japanese Laid-Open Patent Publication No. 63-190125, or in order to improve the yield of the upper layer portion of the packing layer, parallel to the pallet traveling direction from the middle portion to the upper layer portion of the packing material of the compounding raw material formed on the pallet. A cylinder is provided, and coke powder or coal powder is blown from the middle part to the upper part of the blended raw material layer supplied on the pallet from this cylinder to control the carbon concentration and reduce the brittle part of the upper part of the filling layer. The method disclosed in Japanese Patent Laid-Open No. 61-195926, and further, the raw material before adding water is classified, and particularly fine particles are packed in a packed layer so as to be 2 to 40% of the total layer thickness. Reference is made to the method disclosed in Japanese Patent Application Laid-Open No. 4-231424, in which the brittle portion is reduced even if it is supplied to the upper layer portion.

By the way, according to the method disclosed in Japanese Patent Laid-Open No. 63-190125, the layer thickness is changed by the temporal and spatial variation of the particle size distribution of the blended raw material or the temporal and spatial variation of the degree of pseudo-granulation. The particle size distribution in the direction was not stable, and there was a limit in reducing the brittle portion in the upper layer of the packing layer.

Further, in the method disclosed in Japanese Patent Application Laid-Open No. 61-195926, the coke powder or coal powder to be blown cannot be uniformly mixed with the pseudo-granulated blended raw material initially supplied on the pallet. The air permeability of the packing layer was not uniform, and the coke powder and coal powder added were blown off and the basic unit of carbon material increased.

Further, in the method disclosed in Japanese Patent Laid-Open No. 4-314424, since the particle size classification is performed using a rather unstable physical phenomenon called pseudo-granulation of the blended raw material, the air permeability of the packing layer is not uniform. Not only that, but also the coke powder and the coal powder added are blown off due to the non-uniformity of pseudo-granulation, and there is a problem that the basic unit of carbonaceous material is increased, as in the above-mentioned JP-A-61-195926.

Even if fluctuations in the particle size distribution of the compounded raw material itself occur or fluctuations in pseudo-granulation occur, the sinterability of the packing layer in the thickness direction is maintained stable, and the air permeability of the packing layer is made as uniform as possible. In order to improve the yield, it is possible to suppress the increase in the basic unit of carbonaceous materials such as coke powder and coal powder to be added, and further to reduce the number of brittle sintered ore layers in the upper layer portion of the packing layer as much as possible. Is the purpose of.

[0017]

[Problems to be Solved by the Invention] In the production of sinter using a Dwightroid sinter machine, in order to avoid weakening (decrease in strength) and deterioration of yield due to insufficient heat in the upper layer of the raw material filling layer. The results of a series of examinations were conducted by conducting a sintering pot test in a laboratory, a test operation using an actual sintering machine,
The following points became clear.

(1) The brittle portion formed after burning and sintering of the raw material packed layer varies depending on the operating conditions, but it is generally an upper layer portion of 50 to 150 mm from the surface. (2) In order to make the upper part of the raw material filling layer a strong sinter layer after burning and sintering, it is effective to add a low melting point substance to the part in advance. (3) Regarding (2) above, CaO-
It contains a eutectic mixture of Fe ₂ O ₃ and has a lower melting point than that of the new raw material. Therefore, the addition of lava ore can increase the melt in the upper part of the packing layer and has high strength. It can be a sintered ore layer. (4) Regarding (2) above, the powdery iron raw material is added by adding the iron raw material in order to accelerate the reaction rate when the raw material reacts with limestone to form a low melting point melt. It is expected that the strength of the upper part of the filling layer will be improved. (5) Mill scale is used as an iron raw material in powder form. This mill scale contains a large amount of FeO. By adding this, FeO-Si is added during the firing process of the raw material packed layer.
Promotes the generation of O ₂ -based melt. Therefore, when mill scale is added to the upper layer part of the packing layer, the melt can be increased, and moreover, due to the heat of oxidation of FeO in the mill scale, the coke mixing ratio of such part can also be reduced. There are advantages. (6) It is possible to increase the burning rate by pseudo-granulating the compounded raw material, and to increase the burning amount itself beyond the average value in the thickness direction of the packed bed, and to further enhance such effects. Is 1mm for pseudo-granulated blended raw material
The following fine-grain coke (Coke oven dry digestion method, CDQ
Pseudo-granulation (addition of cyclone dust, etc.) generated in (coke mixing ratio higher than average value)
And supply this to the upper layer of the packing layer. (7) Further, it is effective to divide the transport path of the raw material-filled layer into a plurality of regions and adjust the suction flow rate for each partition to control the firing rate in the thickness direction of the raw material-filled layer. Specifically, the suction air volume is reduced while the upper part of the packing layer, which has a low cooling rate, is burning, and conversely, when the lower part of the packing layer is burning, it is over-melted due to excessive heat, so suction It is effective to increase the air volume (this kind of control can raise the temperature of the upper layer of the packing layer and maintain the high temperature state for a long time, which improves the melting rate of the compounded raw materials and is advantageous in improving the yield. ).

The present invention is based on the above findings.

That is, according to the present invention, the raw material-filled layer is sequentially formed on the movable pallet incorporated in the Dwightroid-type sintering machine, and the raw material-filled layer is burned and sintered as the pallet moves. A method for producing a sintered ore, which comprises blending return ore at a ratio of 25 to 95 wt% in a region of 50 to 150 mm from the surface of the packed bed before burning and sintering the raw packed bed. , In this invention,
It is also possible to mix mill scale in the proportion of 1 to 6 wt% instead of the return ore.

For the raw material-filled layer, a pseudo-granulated mixture of raw materials can be applied. Particularly, in the region of 50 to 150 mm from the surface of the raw-material-filled layer, the mixed raw material has a particle size of 1 mm or less. Shall contain fine coke
(After the compounded raw material is pseudo-granulated, -1 mm of fine coke is added thereto and further pseudo-granulated).

Further, according to the present invention, the raw material filling layer is sequentially formed on the movable pallet incorporated in the Dwightroid type sintering machine, and the raw material filling layer is burned and sintered in accordance with the movement of the pallet. A method for producing a sintered ore characterized by dividing a transport path of a raw material packed layer into a plurality of regions and adjusting a suction flow rate for each partition to control a firing rate in a thickness direction of the raw material packed layer. The above-mentioned raw material packed layer may be a general raw material packed layer which has been conventionally used, or of course, as defined in the present invention, in addition to those containing return ores, those containing mill scale, Alternatively, a pseudo-granulated mixture of raw materials can be applied.

Now, FIG. 1 shows a configuration of equipment suitable for carrying out the present invention. In the figure, 1 is a mobile pallet of a Dwightroid sinter, and 2 is a feed hopper (composed of a chute and a drum feeder) for supplying a blended raw material to the mobile pallet 1 to form a raw material packed layer. Therefore, this feed hopper 2 is a main hopper 2a that stores commonly used compounded raw materials that have been conventionally used.
And a sub hopper 2b for storing a blended raw material (25 to 95 wt% in case of return ore and 1 to 15 wt% in case of mill scale) containing relatively large amount of return ore or mill scale.
Consists of.

Further, 3 is a hopper for returning ore or mill scale distribution, 4 is a belt conveyor for feeding the ore or mill scale cut out from the hopper 3, and 5 is a simple mixer. The returned return ore or mill scale is stored in the sub hopper 2b. Reference numeral 6 denotes an ignition source for igniting the raw material packed layer g, and reference numeral 7 denotes a path connected to a suction blower through which the suction air volume is adjusted.

Main hopper 2a and sub hopper 2
The mixed raw materials are supplied from b respectively with a time lag to form a two-layer raw material-filled layer g on the movable pallet 1, which is burned and sintered until the other end of the pallet 1 is reached. A sinter cake (lump) is produced.

[0026]

In the present invention, when producing a sintered ore,
Since a raw material that produces a large amount of melt is mixed in the upper portion of the raw material filling layer and burned and sintered, the strength of the portion can be enhanced.

In the present invention, the mixing ratio of the return ore in the mixed raw material is set to 25 to 95% by weight because the reason is 25% by weight.
This is because if the content is less than 100%, there is no effect of adding the return ore, and if it exceeds 95% by weight, no ignition occurs.

When adding mill scale,
If it is less than 1 wt% with respect to the total amount of the blended raw materials, the effect of adding mill scale cannot be expected, while if it is added in excess of 15 wt%, no further effect can be expected, so 1 to 15 wt% Blend in the ratio of.

FIG. 2 shows the configuration of equipment suitable for using pseudo-granulated blended raw materials. In FIG. 2, reference numeral 8 is a coke tank, 9 is an ore tank, 10 is an auxiliary raw material tank, 11 is a drum mixer for mixing the raw material cut out from each tank while adding water, and pseudo granulating, 12 is pseudo granular A distributor for supplying the converted raw material to the main hopper 2a and the sub hopper 2b, and 13 is a coke storage hopper. The coke is supplied from the storage hopper 13 and the raw material after pseudo-granulation is further mixed by the simple mixer 5 to simulate. Granulate.

Using the equipment having the configuration as shown in FIG. 2 above, in the pseudo-granulated blended raw material, the raw material packed layer g containing fine coke (-1 mm) only in the upper layer portion thereof.
By forming, it is possible to secure good air permeability without substantially increasing the amount of coke.

FIG. 3 exemplifies a facility in which the transport path for the raw material packing layer g is divided into three regions, and the suction flow rate can be adjusted for each of the regions. In the equipment having such a configuration, the suction blowers 15, 16 and 17 connected to the electrostatic precipitator 14 are used to adjust the suction air volume of the upper layer portion, the middle layer portion and the lower layer portion of the packing layer g to perform firing in the thickness direction. The speed can be controlled, and thus the strength in the upper layer portion of the packing layer g can be improved without increasing the amount of coke used.

The adjustment of the suction air volume by the suction blower can be applied to the equipment having the configuration shown in FIGS. 1 and 2 above, and in this case, more accurate control can be performed.

FIG. 4 shows the structure of a conventional sintering machine. In such a structure, it is not possible to control the firing rate of the raw material filling layer g, especially the upper layer portion, by adjusting the damper. Although it is possible, the pressure loss in the upper layer portion cannot be recovered until it reaches the mine ore side of the sintering machine, that is, such a sintering machine cannot avoid a decrease in productivity.

[0034]

【Example】

Example 1 Table 1 was prepared using equipment having the configuration shown in FIG.
In order to combust and sinter raw materials with a mixing ratio such as that shown above to form sinter, the increase ratio of return ore in the upper part of the raw material filling layer (range of 50 to 150 mm from the surface of the filling layer) is used. The changed operation was performed, and the coke intensity and the yield of the packed bed at that time were investigated. The operating conditions at that time are shown in Table 2, and the results are shown in FIGS.

[0035]

[Table 1]

[0036]

[Table 2]

As is clear from FIGS. 5 and 6, when the mixing ratio of the return ore in the upper part of the packing layer is increased, the intensity of coke per unit is almost constant even though the basic unit of coke is almost constant. It was confirmed that the yield was improved and the yield was improved (as a result, the total yield was improved).

Example 2 The same operation as in Example 1 was carried out except that mill scale was blended in the upper layer of the raw material packed layer, and the coke unit consumption and the yield of the packed layer at that time were investigated. The results are shown in FIGS. 7 and 8.

As is clear from FIGS. 7 and 8, the mixing ratio of the mill scale is 1 to the upper layer portion of the raw material filling layer.
It was confirmed that when the content increased to 15%, the strength of such a part could be increased and the yield was improved (the coke consumption was almost constant).

Example 3 Table 3 was prepared using the equipment having the structure shown in FIG.
Combusting a raw material (pseudo-granulated) having a compounding ratio as shown below on a pallet under the conditions shown in Table 2 above,
The operation of sintering is performed, and the temperature change of the raw material packed layer at that time, the strength of the sintered ore (the upper layer of the raw material packed layer, the middle layer,
The sinter ore corresponding to each part of the lower layer and the yield situation were investigated. The results are shown in FIGS. 9, 10 and 11.

[0041]

[Table 3]

In the operation according to the present invention, as shown in FIG. 9, the temperature distribution in the thickness direction of the raw material packing layer is almost constant, the drop strength is sufficiently high as shown in FIG. 10, and the yield is high. It was also confirmed that, as for Fig. 11, it was remarkably improved.

Example 4 Table 1 is prepared by using the equipment having the structure shown in FIG.
The blended raw materials after pseudo-granulation having the blending ratio as shown below were burned and sintered on a pallet under the conditions shown in Table 4. Fig. 12 shows the state of change of the suction pattern by the suction blower, Fig. 13 shows the state of temperature change in the thickness direction of the raw material filling layer, and Fig. 14 shows the strength of the sinter (upper layer, middle layer of the raw material filling layer,
The results of a survey of the sintered ore corresponding to each part of the lower layer are shown below.

[0044]

[Table 4]

As is clear from FIG. 14, the sintered ore in the upper layer portion of the raw material-filled layer has a significantly higher strength than the sintered ore manufactured according to the conventional method, and the yield can be greatly improved. did it.

[0046]

As described above, according to the present invention,
It is possible to increase the strength of the sintered ore without increasing the amount of coke used, which is advantageous not only for improving the yield, but also because the cost for manufacturing the sintered ore is low. Cost reduction is also possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of equipment suitable for carrying out the present invention.

FIG. 2 is a diagram showing a configuration of equipment suitable for carrying out the present invention.

FIG. 3 is a diagram showing a configuration of equipment suitable for carrying out the present invention.

FIG. 4 is a diagram showing a configuration of a conventionally used sintering machine.

FIG. 5 is a diagram showing the results of an investigation of the yield status of a raw material filling layer.

FIG. 6 is a diagram showing the results of investigating the strength of a coke unit and the strength of a sinter.

FIG. 7 is a diagram showing the results of an investigation of the yield status of a raw material filling layer.

FIG. 8 is a diagram showing the results of investigating the intensity of coke unit and the strength of sinter.

FIG. 9 is a diagram showing the results of investigating the temperature in the raw material packed layer.

FIG. 10 is a diagram showing a result of investigating the drop strength of the sintered ore.

FIG. 11: Production rate, yield, unit of coke, layer thickness in the upper layer part of the raw material filling layer, which are involved in the production of sinter.
It is the figure which compared and showed the particle size.

FIG. 12 is a diagram showing a comparison of suction patterns by suction blowers.

FIG. 13 is a diagram in which the results of investigating the temperature in the raw material packed layer are wet.

FIG. 14 is a view showing a result of examining the strength of sinter.

[Explanation of symbols]

 1 Mobile pallet 2 Mining hopper 3 Increase hopper 4 Belt conveyor 5 Simple mixer 6 Ignition source 7 Path 8 Coke tank 9 Ore tank 10 Sub-material tank 11 Drum mixer 12 Distributor 13 Storage hopper 14 Electrostatic precipitator 15 Suction blower 16 suction blower 17 suction blower

Claims (5)

[Claims] 1. A raw material packed layer is sequentially formed on a movable pallet incorporated in a Dwightroid type sintering machine, and the raw material packed layer is burned when the raw material packed layer is burned and sintered in accordance with the movement of the pallet. Prior to sintering, a method for producing a sintered ore, which comprises blending return ore at a proportion of 25 to 95 wt% in a blending raw material region of 50 to 150 mm from the surface of the filling layer. 2. The mill scale is replaced by 1 to 15 wt% instead of the return ore.
The method according to claim 1, wherein the composition is added in a ratio of%. 3. The raw material filling layer is obtained by quasi-granulating the blended raw material, and is 50 to 150 mm from the surface of the raw material filling layer.
3. The method according to claim 1 or 2, wherein the region (1) contains coke having a size of 1 mm or less when the compounded raw material is pseudo-granulated. 4. A raw material packed layer is formed by sequentially forming a raw material packed layer on a movable pallet incorporated in a Dwightroid-type sintering machine and burning and sintering the raw material packed layer as the pallet moves. Is divided into a plurality of regions, and the suction air volume is adjusted for each partition to control the firing rate in the thickness direction of the raw material packed layer. 5. The method according to any one of claims 1 to 3, wherein the feed path of the raw material filling layer is divided into a plurality of regions, and the suction air volume is adjusted for each division to adjust the firing rate in the thickness direction of the raw material filling layer. Controlled sinter production method.