JP2606881B2 - Sintering raw material charging method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention can use coarse-grained sintered ore used as a flooring as a product and can produce by-product quicklime useful as a binder. The present invention relates to a method for charging a sintering material that can be used.

[Conventional technology]

In the method of producing sintered ore from iron ore raw materials such as fine ore, iron ore powder of about 10 mm or less, about 2 mm on average, is mixed with coke of an appropriate particle size and, if necessary, limestone powder of 3 mm or less. Is supplied to a sintered pallet.
Then, the coke in the surface layer of the supplied sintering raw material is ignited, the coke is burned while sucking air downward, and the fine ore is sintered by the combustion heat generated at this time.

Here, when distributing the sintering raw material with a uniform particle size distribution along the height direction of the raw material layer, the lower part of the raw material layer is caused by an increase in the degree of air preheating due to an increase in the sintering completion zone inside the raw material layer. The higher the temperature, the more it tends to over-melt. Further, in the surface layer, since the suctioned outside air which is not preheated is used in the combustion zone, the temperature tends to be insufficient and the degree of sintering tends to be insufficient. As a result, the strength of the sintered ore is reduced, and the sintered ore is pulverized when subjected to post-treatment such as crushing and sieving, so that the proportion of the ore not used as a blast furnace charging material increases.

Therefore, the present inventors set a plurality of strips along the flow direction of the sintering raw material in order to load the sintering raw material into the pallet of the sintering machine while distributing with a continuous particle size distribution under stable conditions. We have developed a charging method using a sieve in which is arranged, and filed applications as Japanese Patent Application Nos. 62-21401 and 62-85543.

When the sifting material is arranged, the sintering material layer formed on the pallet of the sintering machine can be provided with predetermined grain size segregation, coke segregation, degree of dispersion and the like. for that reason,
Compared with the conventional charging method, the sintering reaction is made uniform, and it becomes possible to produce sinter with a high yield.

By the way, on the pallet filled with this sintering raw material,
Usually, a flooring layer having a thickness of about 20 to 30 mm is formed. This flooring layer is provided for the purpose of protecting the great bar from the falling of the sintering raw material from the gap between the great bars laid on the lower surface of the pallet and the high heat generated during the firing process. As a raw material used for this flooring, it was common to return a part of the sinter produced once and use it. Returning and using the sintered ore in this way causes a reduction in the ratio used as a blast furnace charge.

Therefore, the present inventors, instead of returning the sintered ore and using it as a bed layer, sieving the sintering raw material to which the coarse ore serving as the bed layer is added to a pallet of a sintering machine by a classifier. Developing to supply while dividing, this is a Japanese patent application
Filed as 61-91876.

[Problems to be solved by the invention]

By charging the sintering raw material using a sieve in which a plurality of strips are arranged, along the height direction of the raw material packed layer formed on the pallet, Segregation and coke segregation with a higher carbon concentration in the upper layer occur. Therefore, the sintering reaction is made uniform, and it becomes possible to produce sintered ore with a high yield.
However, it is desired to further improve the ventilation by forming a packed layer by sieving and sizing, to reduce the load on the suction blower, and to reduce the power cost.

As a means for this, it is effective to add quicklime as a binder to strengthen granulation and coarsen the raw material. However, quicklime is an expensive material, and the effect of adding it is offset from the viewpoint of economic efficiency, and it is not possible to reduce the production cost. As described above, there is still a limit in reducing the production cost of sinter by adding expensive quicklime.

Therefore, the present invention has further improved the method of forming the floor covering layer, and is capable of producing expensive quick lime by-product by a simple method and suppressing the generation of SOx, NOx and the like. The purpose is to carry out charging.

[Means for solving the problem]

In order to achieve the object, the method for charging a sintering raw material according to the present invention includes, from a lower layer to an upper layer, a pallet of a sintering machine through a screen in which a plurality of strips are arranged along the flow direction of the sintering material. In the method of charging the sintering raw material so that the particle size becomes smaller in the direction, the limestone containing particles of 3 mm or more and / or the particle size 3
By mixing limestone agglomerated to at least mm with the sintering raw material and charging it onto a pallet via the sieve, a bedding composed of a coarse-grained portion in the limestone and a coarse-grained portion in the sintering raw material The method is characterized in that a layer is formed.

〔Example〕

Hereinafter, the features of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the outline of the apparatus used in the first embodiment of the present invention.

In the present embodiment, a conveying means such as a belt conveyor for mixing limestone 3 having a particle diameter of 3 mm or more (hereinafter simply referred to as limestone) is provided in the middle of the conveying path 2 of the sintering raw material 1. As sintering raw material 1, the particle size is 10mm or less,
Fine ore of about 2 mm on average is used. The particle size of limestone 3 is 20mm or less, and the particle size of 3mm or more is about 30%.
Occupy. The limestone 3 having a particle diameter of 3 mm or more and a part of the coarse ore in the sintering raw material having a particle diameter of 3 mm or more are classified by a subsequent charging device and used as a floor covering material.

The sintering raw material 1 containing the limestone 3 is once stored in the surge hopper 5 and then cut out by a fixed amount. The sintering raw material 1 cut out from the surge hopper 5 is sent to the drum feeder 6, and falls on the inclined chute 7 via the peripheral surface of the drum feeder 6. Below this inclined chute 7,
A screen 8 in which a plurality of strips are arranged along the flow direction of the sintering raw material 1 is arranged. The strips forming the screen 8 are held such that the gap between the strips is small on the base end side and large on the tip end side. Therefore, sieve 8
Is smaller on the inclined chute 7 side and larger on the tip side.

When the sintering raw material 1 containing the limestone 3 flowing down from the inclined chute 7 flows on the sieve 8, the sintering raw material 1 having a small particle size preferentially passes through the sieve on the base end side. And large-grained limestone and coarse ore in the sintering raw material are:
Only when it is on the tip side does it pass through the flume. Since the sintering raw material 1 is supplied while being classified by the sieve 8, the pallet 9 of the sintering machine arranged below the sieve 8 is provided.
On the upper side, a raw material filling layer 10 mainly composed of the fine-grained portion of the sintering raw material 1 and the lower layer mainly composed of the coarse-grained limestone and the coarse-grained ore in the sintering raw material is formed. In particular, coarse particles are concentrated just above the lowermost great bar. On the surface layer of the raw material filling layer 10, fine coke added to the sintering raw material 1 in advance is arranged. If necessary, coke is further sprayed on the upper portion of the raw material filling layer 10, and the coke is ignited and burned, so that the raw material filling layer 10 is sintered.

The upper part 11 of the raw material filling layer 10 has a particle size segregation that becomes finer toward the upper part in response to the change of the sieves, and in many cases, coke segregation having a high carbon concentration is formed. Therefore, the ignitability and heat pattern of the upper layer portion 11 are improved, and the sintering reaction is smoothly performed. In the lower layer portion, uneven scorching is reduced by coarsening and sizing, and the yield and air permeability are improved. On the other hand, the coarse particle concentration portion at the lowermost part of the raw material filling layer 10 is used as the floor layer 12.

Here, the bedding layer 12 is composed of coarse-grained limestone 12a and coarse-grained ore 12b.
Therefore, even if the coarse-grained limestone 12a receives heat and is powdered or generates a supermelt due to the reaction between the limestone and the ore, it is absorbed in the gaps between the coarse-grained ores 12b. for that reason,
The sintering reaction is carried out smoothly without the deterioration of air permeability, and the decarboxylation reaction of lime that produces quicklime is also ensured. In this regard, if the bedding layer 12 is composed of only limestone, the limestone is likely to be powdered and clogged with the great, and is in an overmelted state at the boundary with the sintering raw material, thereby impairing the gas permeability of the raw material filling layer. Thus, the sintering reaction is delayed.

Usually, limestone is added as a CaO source of the sinter, and is determined in balance with the amount of SiO _{2 in} the sinter. SiO ₂
The ratio of CaO to CaO / SiO ₂ is usually about 1.6, and the amount of limestone is about 13%. Therefore, in the present embodiment, the compounding amount of limestone with respect to the sintering raw material is 13.5
%.

The proportion of 33.5mm or more of this 13.5% limestone 3 is about 30
%, About 4% of the limestone blended amount of 13.5% becomes coarse limestone 12a in the floor covering 12 and changes to quicklime. The quicklime generated in this way is stored in the return hopper 13 together with the unsintered return. The quicklime and the ore cut out from the return hopper 13 are used as the raw material 1 for sintering.
Limestone 3 and then granulated. Therefore, the raw material Ca excluding the limestone used as the floor bedding in the system
O is maintained at approximately 13.5%. In addition, at the time of this mixed granulation, coarse limestone 12a that became a part of the bedding 12 was changed to quicklime and returned to the return hopper 13 together with the return, so this quicklime became the binder. The granulation of the sintering raw material 1 itself was also strengthened.

In this example, as a raw material other than limestone, a raw material having a particle size of 15 mm or less was used. Therefore, by forming the bedding layer 12 mainly with limestone of 3 to 20 mm and ore of 3 to 15 mm, it was possible to replace the sintered ore used as the flooring material.

The size of limestone containing particles of 3 mm or more should be determined in consideration of the calorific level determined by the amount of coke added during sintering. When the caloric level is low, the ratio of the mixed limestone to quick lime is small, and limestone having a large particle size, for example, limestone having a particle size of 5 mm or more, remains as it is. The limestone having a grain size of 5 mm or more is placed on the sieve at the same time as the product of the sintered ore having a grain size of 5 mm or more, and is transferred to the blast furnace charging material side. Such a large-diameter limestone is not preferable for a reaction in a blast furnace. Therefore, it is preferable that the particle size of the limestone mixed with the sintering raw material 1 be 5 mm or less after the portion which has become the quicklime after being subjected to heat as the floor layer 12 is peeled off. The diameter is preferably 8 mm or less. Further, limestone having a size of 5 to 8 mm may be added to the currently used limestone of 3 mm or less and used.

When the sintering raw material 1 having a small proportion of the coarse ore 12b constituting a part of the bedding layer 12 is used, the coarse ore 4 having a large proportion containing 3 mm or more particles is used as the sintering raw material 1. It is preferable to mix them separately.

Reference numeral 14 in the figure denotes a mixer for uniformly mixing the mixture of the sintering raw material 1, the limestone 3 and the like.

When the raw material-filled layer 10 having the bedding layer 12 thus formed is sintered, it is not necessary to return the sintered ore to provide the bedding layer. As a result, the proportion of sintered ore directly sent as blast furnace feedstock increases. For example, in the past, about 3% by weight of the produced ore was returned as flooring material, but since this is no longer necessary, the yield near the sum of the damage due to recycling and the increase in layer thickness has been reduced. Improvements were made. At the same time, waste heat generated during sintering can be used to produce quicklime used as a binder or the like for granulation of the sintering raw material, thereby providing a sintering line with high added value. Here, when the coarse-grained portion of the raw material is small, the sinter may be used as the floor bedding by a commonly used bedding line.

Japanese Patent Application Laid-Open No. 61-3847 proposes that limestone be used as a flooring layer. But,
Simply supplying limestone onto the pallet 9 heats the limestone during sintering and causes excessive melting. As a result, the great bar is clogged, the air flow resistance of the air sucked in the thickness direction of the raw material filling layer 10 is increased, and the sintering reaction is inhibited.

In this regard, in the present invention, the sintering raw material 1 is mixed with the limestone 3, and the respective coarse-grained portions are supplied onto the pallet 9 of the sintering machine via the sieve 8, thereby forming the floor covering layer 12. Due to the formation, air permeability required for sintering is secured, and at the same time, the reaction of calcining the coarse-grained limestone 12a in the limestone 3 to generate quick lime is sufficiently performed. Therefore, sintered ore is produced with a high yield.

FIG. 2 is a diagram for explaining a second embodiment in which agglomerated limestone is used.

In the present embodiment, 13.5%
However, 2.7%, which is 20% of the 13.5%, was separately stored in a hopper as limestone for agglomeration, and was agglomerated to 3 mm or more and mixed with a sintering raw material. This 2.7
%, Except that the limestone is agglomerated to 3 mm or more and mixed with the sintering raw material. The remaining 10.8% excluding the agglomerated limestone is used as limestone 3. . Therefore, in the following description, the steps from agglomeration of the granular limestone to mixing with the sintering raw material will be described.

The hopper 21 stores powdered limestone 22 having a particle size of 3 mm or less. The powdery and granular limestone 22 is transported to the granulator 23 by an appropriate transport means such as a belt conveyor. The powdered limestone 22 is kneaded with a binder 24 in a granulator 23 and agglomerated to a particle size of 3 mm or more. This agglomeration is also possible with a molding machine or the like. As the binder 24 used at this time, an organic binder such as pulp waste liquid and tar, and an inorganic binder such as cement, clinker, gas ash, and quick lime are used.

The agglomerated limestone is put into the sintering raw material carried out of the mixer 14 and then charged into the pallet 9 through the surge hopper 5 and the drum feeder 6 together with the sintering raw material. Alternatively, the agglomerated limestone can be directly charged to the screen 8 or directly to the pallet 9 via a floor hopper (not shown) without passing through the surge hopper 5 and the drum feeder 6.

In this way, when limestone obtained by agglomerating the granular material is used, the reaction of converting limestone into quicklime is promoted when sintering reaction of the raw material filling layer 10 on the pallet 9, and quicklime is efficiently produced. You.

In the granulator 23, in addition to the binder 24, it is preferable that a carbonaceous material 25 such as coke and pulverized coal be further mixed into the granular limestone 22. As the carbonaceous material 25, a material having a particle size of about 1 mm or less is added to the powdery limestone 22 at a ratio of 30% or less.
The mixed carbonaceous material 25 is contained in the agglomerated limestone particles in a dispersed state, and serves as a heat source necessary for the quicklime generation reaction,
The conversion from limestone to quicklime is further promoted.

[Effects of the Invention] As described above, in the present invention, limestone containing particles of 3 mm or more and / or limestone agglomerated to 3 mm or more in the sintering raw material supplied to the pallet of the sintering machine. Is formed, and a coarse bedding layer is formed by the coarse-grained portion in the limestone and the coarse-grained portion in the sintering raw material. Since the proportion occupied by the grain portion is increased, and furthermore, a part of the sintered ore may be used as the bedding in the existing bedding line, the raw material filling layer can be formed on the pallet without hindering the sintering reaction.

The coarse-grained limestone and / or agglomerated lime used as one component of the bedding layer becomes useful quicklime and also suppresses emission of harmful substances such as SOx and NOx into the atmosphere. Thus, according to the present invention, since the sintered ore is not used as the floor covering material, it is possible to increase the ratio of the sintered ore charged into the blast furnace and to provide a high value-added sintering line. Becomes possible.

[Brief description of the drawings]

FIG. 1 shows a sintering raw material charging apparatus used in the first embodiment of the present invention, and FIG. 2 shows a sintering raw material charging apparatus used in the second embodiment. 1: Sintering raw material, 1a: Fine iron ore 2: Transport route, 3: Limestone 4: Coarse ore, 5: Surge hopper 6: Drum feeder, 7: Inclined chute 8: Fluy, 9: Pallet 10: Raw material filling layer , 11: Upper layer 12: Bedding layer, 12a: Coarse limestone 12b: Coarse ore, 13: Return hopper 14: Mixer, 21: Hopper 22: Powdered limestone, 23: Granulator 24: Binder, 25 : Charcoal

Claims (1)

(57) [Claims] 1. A sintering raw material is charged into a pallet of a sintering machine through a sieve in which a plurality of strips are arranged along the flow direction of the sintering raw material so that the grain size decreases from the lower layer to the upper layer. In the method, limestone containing particles of 3 mm or more and / or limestone agglomerated to a particle size of 3 mm or more are blended into a sintering raw material, and charged on a pallet via the sieve, whereby coarse particles in the limestone are mixed. A method for charging a sintering raw material, comprising forming a floor covering layer comprising a portion and a coarse-grained portion in the sintering raw material.