JP6287511B2 - Pretreatment method of sintering raw materials - Google Patents

Description

  The present invention relates to a granulation treatment that is performed in advance on a sintering raw material charged in a sintering machine in order to improve the productivity of the sintering machine.

The productivity of a sintering machine for producing sintered ore is expressed as firing rate × yield after firing. Therefore, in order to improve the productivity of the sintering machine, it is necessary to improve the firing rate and / or the yield after firing.
The firing speed is determined in consideration of the red tropical descending speed in the sintering machine pallet, the pallet area, the bulk density of the sintered raw material, and the like. In order to increase the red tropical fall rate and improve the firing rate, it is important to improve the air permeability of the raw material layer. Therefore, air permeability is improved by granulating a sintering raw material beforehand and reducing fine powder.

  However, with the recent deterioration of resources, for example, a sintering raw material containing 15% by mass or more of fine powder (fine ore) under 500 μm is increasing. The importance of reducing granulated fines) is increasing.

  Therefore, Patent Document 1 describes granulating a sintered raw material with high moisture for the purpose of strengthening the granulation of the sintered raw material. More specifically, a method of granulating a sintered raw material mainly composed of fine powder with a first granulator and then supplying the granulated material together with another sintered raw material to a second granulator. Is described. In this method, the water added in the first granulator is equivalent to the water content absorbed by the sintering raw material mainly composed of fine powder, and further 2.5% by mass to 4.0% by mass of the water content equivalent. It is characterized by the amount of the following water added.

  Moreover, in patent document 2, like the invention of patent document 1, the granulation system is divided into two systems, and one of the divided raw materials is granulated with a water content of 8.0 to 11.1% by mass to produce one pseudo particle. And the other raw material is granulated at a moisture content of 6.0 to 7.5% by mass to form the other pseudo particle, and both pseudo particles are supplied to the sintering machine without mixing with a drum mixer. (For example, claim 1).

JP 2008-101263 A JP 2009-209408 A

  However, in the case of the method described in Patent Document 1, granulation is performed by adding 2.5% by mass or more and 4.0% by mass or less of water to the water content of the sintering raw material. Although the granulation property is good, the adhesion of the granulated product itself is also increased. Therefore, in the process of granulating the granulated material together with other sintered raw materials in a second granulator such as a drum mixer, the coagulant blended with the other sintered raw materials is the first. It adheres to the granulated material granulated by this granulator and forms a coagulant layer on its surface. As a result, a part of the buried condensed material does not generate oxidation heat, resulting in insufficient firing.

  On the other hand, in the method described in Patent Document 2, in order to supply one pseudo particle and the other pseudo particle to a sintering machine without mixing with a drum mixer, for example, a coagulant mixed in the other sintering raw material Is not taken into one of the pseudo particles. Therefore, it is possible to suppress the occurrence of insufficient firing due to the buried of the aggregating material. However, since one pseudo particle has a lot of moisture, the pseudo particles tend to stick together and become agglomerated, and the one pseudo particle and the other pseudo particle are not mixed with a drum mixer or the like, for example, a sintering machine. When being stacked on the belt conveyor in the process of transport to and fed to the sintering machine, a portion where one pseudo particle is unevenly distributed in the sintering raw material supplied to the sintering machine, that is, a portion where moisture is unevenly distributed occurs, This causes insufficient firing during sintering.

  Note that claim 3 of Patent Document 2 describes that the moisture difference between one pseudo particle and the other pseudo particle is limited (3.1% by mass or less) as a configuration for suppressing insufficient firing. This method makes it possible to suppress insufficient baking due to the uneven distribution of moisture, but it is a moisture control that is not based on granulation properties, which causes a lack of moisture and excessive moisture during granulation. In the case of insufficient moisture, the ungranulated fine powder reduces the air permeability during sintering, leading to a decrease in the firing rate and insufficient firing. On the other hand, excessive moisture causes an increase in the moisture of the entire sintering raw material supplied to the sintering machine (the amount of water brought into the sintering machine), which leads to insufficient firing under a constant firing rate.

  The present invention has been made in view of such circumstances, and improves the productivity of the sintering machine by suppressing the shortage of firing during sintering that occurs when a sintering raw material with a lot of fine powder is granulated with high moisture. It is an object of the present invention to provide a pretreatment method for a sintering raw material that can be used.

In order to achieve the above object, the sintering raw material pretreatment method according to the present invention granulates sintering raw material A containing 15% by mass or more of fine powder of 500 μm or less in a moisture content of 10% by mass to 13% by mass. As an object AA,
The granulated product AA is mixed with a sintering raw material B having a moisture content of 0% by mass to 9% by mass to obtain a granulated product AAB.
The granulated product AAB is added to the inlet side of a granulating apparatus for granulating a sintered raw material C containing iron ore and a coagulant.

The coagulant mainly contains carbon, and is a material that generates heat by oxidation. For example, it refers to coal and coke.
Moreover, the said water | moisture content (mass%) is a value calculated by following Formula.
Moisture = Amount of added water / (Amount of sintering raw material + Amount of added water) × 100

Sintered raw material A containing 15% by mass or more of fine powder (powder ore) of 500 μm or less is a difficult-granulating raw material with a lot of fine powder and difficult to granulate. 13% by mass) to obtain a granulated product AA. However, since the granulated product AA contains a lot of moisture, in the subsequent granulation process, the aggregated material adheres to the granulated product AA, and a condensed material layer is formed on the surface thereof. Does not generate oxidation heat, resulting in insufficient firing.
Therefore, in the present invention, the low-moisture sintered raw material B is produced by mixing the granulated material AA that causes the condensing material to be buried and the low-moisture (water 0 mass% to 9 mass%) sintered raw material B. A granulated product AAB applied to the surface of the granular product AA is manufactured. Since the granulated product AAB has a low-moisture sintered raw material B on its surface, the adhesive strength is smaller than that of the granulated product AA. Therefore, even if the granulated material AAB is added to the inlet side of the granulating apparatus for granulating the sintered raw material C containing the iron ore and the coagulating material, the sintered raw material C hardly adheres to the granulated material AAB. The material is not buried, and the firing shortage due to the condensing material buried and the uneven distribution of moisture can be suppressed.

Moreover, in the pre-processing method of the sintering raw material which concerns on this invention, the water | moisture content (mass%) of the said sintering raw material C is decreased rather than the water | moisture content (mass%) of the said granulated material AAB, and the water | moisture content of the said sintering raw material C 2 mass% or more, and the difference in moisture from the granulated product AAB is preferably 6 mass% or less.

  If the difference in moisture between the sintered raw material C and the granulated product AAB is large, that is, the moisture of the sintered raw material C is too small compared to the granulated product AAB, the coagulant blended in the sintered raw material C will be granulated. It becomes easy to adhere to AAB. Therefore, by increasing the water content of the sintered raw material C until the difference in water content with the granulated material AAB is 6% by mass or less, the granulated material substantially composed of the sintered raw material C increases, and the present invention. The effect becomes remarkable.

  In the pretreatment method of the sintered raw material according to the present invention, the granulated product AAB in which the low-moisture sintered raw material B is applied to the surface of the granulated product AA containing a large amount of fine powder and containing a large amount of water is manufactured. Since the sintering raw material C containing the agglomerated material is granulated together with the granulated product AAB, insufficient sintering due to the embedding of the agglomerated material and the uneven distribution of moisture that occurs when the sintered raw material with a lot of fine particles is granulated with high moisture is suppressed. The productivity of the kneading machine can be improved.

It is a schematic diagram which shows the outline of the pre-processing method of the sintering raw material which concerns on one embodiment of this invention. It is the graph which showed the relationship between the moisture content of granulated material AA, and the amount of residual fine powder in granulated material AA. It is the graph which showed the relationship between the moisture content of granulated material AAB, the ratio of the sintering raw material of 10 mm over of the granulation apparatus c exit side, and the yield after pot baking. It is the graph which showed the influence which the water | moisture-content difference of the sintering raw material C and the granulated material AAB has on the yield after a pan baking, when the water | moisture content of the sintering raw material B is 4 mass%. It is the graph which showed the influence which the water | moisture-content difference of the sintering raw material C and the granulated material AAB has on the yield after pan baking when the water | moisture content of the sintering raw material B is 9 mass%. It is the graph which showed the influence which the water | moisture-content difference of the sintering raw material C and the granulated material AAB has on the yield after a pan baking when the water | moisture content of the sintering raw material B is 0 mass%.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

A pretreatment method for a sintering material according to an embodiment of the present invention will be described with reference to the schematic diagram of FIG.
(1) Water (moisture of 10% by mass to 13% by mass) is added to the sintering raw material A containing 15% by mass or more of fine powder (powder ore) of 500 μm or less, and the granulated product AA by a granulator a10 such as a stirrer. Granulate. Since the granulated product AA contains a lot of moisture, it has strong adhesion and is easily agglomerated as shown in FIG.

(2) Sintering raw material B having a moisture content of 0% by mass to 9% by mass is added to the granulated product AA, and the granulated product AAB is granulated by a mixer 12 such as a pan pelletizer. The agglomerated granulated product AA is dispersed in the mixer 12, and the sintered raw material B with less water adheres to the surface of the granulated product AA. Since the granulated product AAB has less water than the granulated product AA, the agglomeration hardly occurs (see FIG. 1).

(3) The granulated product AAB is added to the inlet side of the granulating apparatus c11 for granulating the sintered raw material C containing iron ore and a coagulating material, and granulated. A drum mixer etc. can be used for the granulator c11. Since the granulated product AAB has a low water content, a granulated product having the granulated product AAB as a core is hardly generated. Therefore, the granulated material of only the sintering raw material C increases (refer FIG. 1).
In addition, it is preferable that the moisture of the sintering raw material C is 2% by mass or more, and the difference in moisture from the granulated product AAB is 6% by mass or less. It may be adjusted by watering or the like.

[Relationship between granulation strengthening and added moisture of sintering raw material A containing fine powder]
In order to clarify the relationship between the granulation strengthening of the sintering raw material A containing fine powder and the added moisture, the residual fine powder (0.5 mm) contained in the granulated product AA granulated using the moisture added to the sintering raw material A as a parameter. The amount of under) was investigated (first test).

A high-speed stirrer (Eirich mixer) is added to 2% by mass of quicklime as a binder and water (water content 9% to 13% by mass) as a binder to sintering raw material A containing 55% by mass of fine powder of 0.5 mm (500 μm) under. ) To granulate the granulated product AA.
Fine powder containing Yandy ore was used for the sintering raw material A, and the granulated product AA was obtained by stirring for 40 seconds with the rotation speed of the high-speed stirrer being 415 rpm.

  And it investigated about the quantity of the residual fine powder (0.5 mm under) contained in the obtained granulated material AA. The amount of residual fine powder contained in the granulated product AA is measured by drying the granulated product AA after the granulation treatment to a moisture content of 0% by mass, and a low-tap shaker for 15 seconds against 0.5 mm sieve of JISZ8801-1. After carrying out mechanical sieving according to the above, the mass under the sieve was measured, and (the mass under the sieve) / (the mass on the sieve + the mass under the sieve) × 100 (mass%) was defined as the amount of residual fine powder.

The test results are shown in FIG. The figure shows the following.
In the case of a sintered raw material having a large amount of fine powder, granulation with 10% by mass or more of moisture reduces ungranulated fine powder (residual fine powder). However, when the water content exceeds 13% by mass, there is a tendency that the adhesion of the sintered raw material to the high-speed stirrer and the like tends to increase, so the upper limit value of the water content is set to 13% by mass.
In addition, when the 0.5 mm under fine powder was tested at 15% by mass to 100% by mass, the numerical value on the vertical axis was different, but when the water content was 10% by mass or more, the ungranulated fine powder decreased. Moreover, the same tendency was seen also when the ratio of the quicklime as a binder was changed by 0 mass%-6 mass%.

[Relationship between moisture of granulated product AAB and adhesion of powder to granulated product AAB]
In order to clarify the relationship between the moisture of the granulated product AAB and the powder adherence to the granulated product AAB, the powder adherence to the granulated product AAB using the moisture of the sintering raw material B added to the granulated product AA as a parameter. The properties and the yield after baking were investigated (second test).

  A sintered raw material A containing 40% by mass of 0.5 mm under fine powder was granulated, and a granulated product AA (water 10% by mass) containing 3% by mass to 5% by mass of 0.5 mm under fine powder was granulated. . The kind and granulation conditions of the sintering raw material A are the same as in the first test.

Then, the sintering raw material B containing 70% by mass of 0.5 mm under fine powder and having moisture of 0, 4, and 9% by mass is added to the granulated product AA and mixed by a pan pelletizer, and moisture of 6.6, 8, 9 .7% by mass of granulated product AAB was produced. The mass ratio of the granulated product AA and the sintered raw material B is determined by the moisture of the granulated product AA, the moisture of the sintered raw material B, and the target moisture of the granulated product AAB. In this test, the mass ratio of the granulated product AA and the sintering raw material B was 2: 1.
For the sintering material B, kneaded dust was used. Moreover, the rotation speed of the pan pelletizer was 29 rpm, and the mixing time (1 to 3 minutes) was adjusted so that the 0.5 mm under fine powder contained in the granulated product AAB would be 5 to 10% by mass.
As a result of visual observation of the granulated product AAB, there was no tendency for the granulated products AAB to stick together, and no tendency to agglomerate.

Next, 10% by mass of 0.5 mm under fine powder, 4% by mass of the coagulation material, and 4% by mass of the sintered raw material C and the granulated product AAB are charged into the granulator c and granulated. To produce a granulated product having a moisture content of 7.5% by mass. The mass ratio of the granulated product AAB and the sintering raw material C was 30%: 70%.
As the sintering raw material C, lobe ore, return ore, and the like were used. Moreover, the drum mixer was used for the granulator c, and water was continuously added in 0 minute-1 minute from the granulation start by a drum mixer. The rotation speed of the drum mixer was 25 rpm, and the granulation time (2 to 3 minutes) was adjusted so that the 0.5 mm under fine powder contained in the granulated product was 0% by mass to 2% by mass. .

About the granulated material granulated by the granulator c, the mass ratio exceeding 10 mm was investigated, and the yield after baking the pot was investigated using a sintering pot test apparatus (not shown).
In addition, the fired product fired by the sintering pot test apparatus was dropped four times from a height of 2 m, and the ratio of remaining 6 mm over was defined as the yield after baking. In addition, since the sintering pot test is affected by fine powder, as described above, the 0.5 mm under fine powder contained in the granulated product granulated by the granulator c is adjusted to 0% by mass to 2% by mass. The reliability of the sintering pot test was ensured.

  The test results are shown in FIG. The white data in the figure shows the result of charging the granulated product AA having a moisture content of 10% by mass into the granulating apparatus c without mixing it with the sintering raw material B. In addition, when the water | moisture content of the sintering raw material B shall be 10 mass%, the water | moisture content of the granulated material AAB will be 10 mass%. Therefore, it can be said that the outline data shows the result of the granulated product AAB produced by mixing the granulated product AA having a moisture content of 10% by mass and the sintered raw material B having a moisture content of 10% by mass.

The figure shows the following.
By coating the granulated product AA with the low-moisture sintering raw material B, the particle size of the granulated product is reduced on the exit side of the granulating apparatus c, and the yield after baking is significantly increased. When the moisture content of the granulated product AAB is low, the amount of the sintered raw material C containing the coagulant is reduced in amount attached to the granulated product AAB, resulting in an increase in the number of granulated products composed of the sintered raw material C. It is presumed that the particle size of the granulated product on the outlet side of the granulating device c has become smaller. It is considered that the coagulant taken into the granulated product having a small particle size is relatively easily oxidized during firing.
On the contrary, as the moisture content of the granulated product AAB increases, the particle size of the granulated product tends to increase. The more the granulated product has a larger particle size (over 10 mm), the lower the yield after baking. As the moisture content of the granulated product AAB increases, the coagulant blended in the sintered raw material C is taken into the granulated product with the granulated product AAB as a core and the particles of the sintered raw material C adhere to it, and oxidation during firing occurs. Presumed to have been suppressed.

  Moreover, when the moisture content of the sintering raw material B is 10% by mass, the granulated material exceeding 10 mm on the outlet side of the granulating device c is remarkably increased as compared with the case where the moisture content is 9% by mass, and the yield after the pot firing is increased. Is also extremely reduced. Therefore, the moisture of the sintering raw material B is set to 9% by mass or less.

  As described above, when the moisture content of the granulated product AAB is reduced by covering the sintered raw material B (the effect is confirmed when the moisture content is 9% by mass or less), the granulation product AA can be strengthened and prevented from agglomerating. At the same time, it is possible to suppress the generation of a granulated product that takes in the coagulant blended in the sintering raw material C and to produce a granulated product that does not cause insufficient firing by the granulating device c. As a result, the productivity of the sintering machine can be improved.

  In addition, when the water | moisture content of the granulated material AA was 13 mass% and when the mass ratio of the granulated material AAB was 10 mass%-60 mass%, it confirmed that it was the same tendency as the above.

[Relationship between moisture of granulated product AAB and moisture of sintered raw material C]
In order to clarify the relationship between the moisture content of the granulated product AAB and the moisture content of the sintering material C, the moisture content of the sintering materials B and C and the difference between the moisture content of the sintering material C and the moisture content of the granulation product AAB were used as parameters. The yield after pot baking was investigated (third test).

Sintering raw materials A, B, C and granulation conditions are the same as in the second test. However, the moisture of the sintering raw material C was set to 0% by mass to 6% by mass.
The test results are shown in FIGS. In addition, the rhombus in the figure is the result of charging the granulated product AA having a moisture content of 10% by mass into the granulating apparatus c without mixing with the sintered material B (the moisture content of the sintered material C is 4% by mass). Is shown.

From these figures, the following can be understood.
When the moisture content of the sintered raw material B is 4% by mass and 9% by mass, if the moisture difference between the moisture content of the sintered raw material C and the granulated product AAB exceeds 6%, the yield after firing decreases.
Moreover, when the moisture of the sintering raw material B is 0% by mass, the moisture of the sintering raw material C becomes less than 2% even if the moisture difference between the moisture of the sintering raw material C and the granulated product AAB is within 6%. , Yield after firing decreases. When the moisture content of the sintering material C is less than 2% by mass, the surface moisture of the sintering material C is substantially 0% by mass, which is considered to be lower than the limit moisture that the materials can adhere to. Therefore, it is presumed that the sintered raw materials C do not adhere to each other and are taken into the granulated product AAB.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and is within the scope of matters described in the claims. Other possible embodiments and modifications are also included. For example, in the above embodiment, a pan pelletizer is used as a mixer, but the present invention is not limited to this, and a drum mixer or the like may be used.

10: Granulator a, 11: Granulator c, 12: Mixer

Claims (2)

The sintered raw material A containing 15% by mass or more of fine powder of 500 μm or less is granulated with a water content of 10% by mass to 13% by mass to obtain a granulated product AA,
The granulated product AA is mixed with a sintering raw material B having a moisture content of 0% by mass to 9% by mass to obtain a granulated product AAB.
A pretreatment method for a sintered material, wherein the granulated product AAB is added to an inlet side of a granulating apparatus for granulating a sintered material C containing iron ore and a coagulant. In the pre-processing method of the sintering raw material of Claim 1, the water | moisture content (mass%) of the said sintering raw material C is less than the water | moisture content (mass%) of the said granulated material AAB, and the water | moisture content of the said sintering raw material C is reduced. A pretreatment method of a sintering raw material, characterized in that the difference in moisture from 2 mass% or more and the granulated product AAB is 6 mass% or less.

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