JP2007113087A - Method for granulating raw material to be sintered - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide granulated particles which have excellent properties to be pseudo-particles effective for improving air permeability in a sintering machine and improving productivity by granulating a raw material to be sintered containing iron ore. <P>SOLUTION: When spraying water and a binder onto the raw material to be sintered containing iron ore before granulating the raw material, spraying at least one part of the water onto the raw material to be sintered is included, by using a water spray means 5 which has been arranged separately from a binder spray means 6. If a total quantity of water is sprayed onto the raw material to be sintered together with a binder component, it is difficult for the water to be uniformly scattered onto the whole raw material to be sintered, which does not give the raw material an adequate granulation effect. However, when at least one part of the water is sprayed from the water spray means different from the binder spray means, the water is uniformly scattered on the whole raw material, and gives the raw material a high granulation effect to form the granulated particles having excellent properties to be pseudo-particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for granulating a sintered raw material in order to improve the sinterability of the sintered raw material containing iron ore and improve the productivity in a sintering machine.

  In general, sintered ore used in blast furnaces is mixed with iron ore by adding auxiliary raw materials, fuel such as coke and additives for granulation, and granulated to form pseudo particles, which are then loaded into a sintering machine. And then baked. That is, when firing in the sintering machine, it is important to sufficiently increase the air permeability in the packed bed of the sintering raw material to increase the combustion efficiency of fuel such as coke and improve the productivity of the sintering machine. Therefore, conventionally, the air permeability is improved by granulating the sintered raw material into pseudo particles.

  The granulated particles are required to have sufficient strength so that the pseudo particles do not collapse during the heat drying and baking processes in the sintering process in the sintering machine. This is because when the pseudo particles collapse in the sintering machine and fine powder of the sintering raw material is generated, the air permeability is impaired and the productivity of the sintering machine is deteriorated.

  Conventionally, as an additive for granulation used in granulation of iron ore or the like, quick lime is widely used as disclosed in, for example, Steelmaking Research No. 288 (1976), pages 9 to 18. ing. Specifically, granulated by sprinkling water in a drum mixer to a sintered raw material in which iron ore is supplemented with a fuel such as a secondary raw material and coke, and quick lime is added as a granulating additive. And preventing the spurious particles from collapsing during the heating and drying and firing processes in the sintering machine. FIG. 2 is a schematic diagram showing a conventional granulation method. From the blending tank 1, a sintered raw material in which quick lime is further blended with a blended raw material such as iron ore, coke, and limestone is transferred to a drum mixer by belt conveyors 2 and 3. 4, and the sintered raw material is mixed and granulated in the drum mixer 4 under watering from the watering nozzle 5, and the granulated material is charged into the sintering machine pallet through a surge hopper not shown in the figure. It is sintered and becomes a sintered ore.

Conventionally, quick lime as an additive for granulation is usually blended in an amount of about 1 to 2% by weight with respect to a blended raw material containing iron ore. In addition, water containing a binder component may be sprinkled as water sprayed in the drum mixer. In the present invention, the binder refers to a material that exhibits the granulation effect of the sintered raw material by thickening or hardening promoting action.
Steelmaking Research No. 288 (1976), pp. 9-18

  In order to improve productivity in the sintering machine, the granulation of the sintering raw material containing iron ore is promoted, and the resulting granulated particles are further improved in quasi-particle formability and dried by heating in the sintering machine. It is desired to prevent generation of fine powder due to disintegration in the firing process. In the conventional method using quick lime as an additive for granulation, by increasing the amount of quick lime added, the pseudo-particulate property can be improved to some extent, but the improvement effect is also limited. In addition, sprinkling water containing a binder component can improve the pseudo-particle formation property, but a sufficient effect is still not obtained. For this reason, the further technique of improving pseudo-particle property is desired.

  In particular, since the depletion of high-quality red ore has progressed in recent years, the application of brown ore-based sintered raw materials that are inferior in sinterability and deteriorate the productivity in the sintering machine has been increasing. At present, it is strongly desired to improve productivity by improving the granulation technology.

  The present invention has been made in view of the above-described conventional situation, granulating a sintering raw material containing iron ore, and improving the air permeability in the sintering machine, and the pseudo-particle property effective for improving the productivity. It aims at providing the method of obtaining the outstanding granulated particle.

  The method for granulating a sintered raw material of the present invention (Claim 1) is a method of granulating by dispersing water and a binder on a sintered raw material containing iron ore and a source of calcium ions, and spraying the binder The water is sprinkled on the sintering raw material by watering means provided separately from the means.

The granulation method of the sintered raw material according to claim 2 is characterized in that, in claim 1, the binder has a funnel viscosity (500/500) measured by the following method of 40 seconds or more.
[Funnel viscosity (500/500) measurement method]
After adding 5 g of slaked lime to 500 ml of binder and stirring for 10 minutes, the funnel viscosity (500/500) based on API standards is measured.

  The method for granulating a sintered raw material according to claim 3 is characterized in that, in claim 1 or 2, the water content of the obtained granulated product is 6 to 9% by weight.

  According to a fourth aspect of the present invention, there is provided the granulation method for a sintered raw material according to any one of the first to third aspects, wherein the binder contains bentonite.

  The granulation method of the sintered raw material according to claim 5 is characterized in that in any one of claims 1 to 4, the binder contains bentonite and silica.

  In addition, in this invention, the moisture content of a granulated material refers to the weight ratio with respect to the whole granulated material of the moisture content contained in a granulated material.

  According to the present invention, by separately spraying water and a binder on a sintering raw material, it is possible to effectively granulate the sintering raw material and obtain granulated particles having excellent pseudo-particle property. In this case, if the total amount of water sprinkled on the sintering raw material is added to the sintering raw material together with the binder component, it is difficult for water to be uniformly dispersed throughout the sintering raw material, and a good granulation effect cannot be obtained. In the present invention, at least a part of the water sprayed on the sintering raw material is sprayed from a watering means different from the binder spraying means, so that the water is uniformly dispersed throughout the sintering raw material. A granulation effect can be obtained, whereby granulated particles having excellent pseudo-particulate properties can be obtained (claim 1).

In the present invention, the binder preferably has a funnel viscosity (500/500) measured by the following method of 40 seconds or more (Claim 2).
[Funnel viscosity (500/500) measurement method]
After adding 5 g of slaked lime to 500 ml of binder and stirring for 10 minutes, the funnel viscosity (500/500) based on API standards is measured.

  The funnel viscosity (500/500) according to the API standard (muddy water test standard by the American Petroleum Institute (American Petroleum Institute)) was measured using a funnel viscometer according to the API standard (in the present invention, 500 ml of binder). Is added to and mixed with 5 g of slaked lime) in a funnel container, and is expressed as the time required for the entire amount of the sample to flow out. In addition, the quantity of the active ingredient contained in a binder does not ask | require.

  In the present invention, water and a binder are preferably added so that the water content of the obtained granulated product is 6 to 9% by weight. The binder preferably contains bentonite (Claim 4), and particularly preferably contains bentonite and silica (Claim 5).

  Embodiments of the granulation method for a sintered raw material of the present invention will be described in detail below.

  The sintering raw material to be granulated in the present invention is usually obtained by adding and mixing quick lime as an additive for granulation to a blending raw material such as iron ore, limestone, and powdered coke that are usually used as sintering raw materials for sintered ore. It is a mixture.

  In this case, if the amount of quicklime added is too small, it is not possible to obtain a granulated product excellent in pseudo-particulateness, and if it is too much, it becomes uneconomical. , And a mixture of fuels such as coke (sintering raw materials other than quicklime), preferably 0.5 to 3% by weight, particularly preferably 1 to 2% by weight.

  In addition, the moisture content of this sintering raw material is about 3 to 6 weight% normally.

  In the present invention, such a sintered raw material is granulated by spraying a binder and water. That is, water is sprinkled by a watering means provided separately from the binder spraying means and granulated.

  The effective component (binder component) of the binder used in the present invention is not particularly limited as long as it exhibits the granulating effect of the sintered raw material by thickening or hardening promoting action. For example, bentonite, guar gum, polyvinyl alcohol (PVA), polyacrylamide, methylcellulose, ethylcellulose, carboxymethylcellulose (CMC), hydroxyethylcellulose, hydroxypropylethylcellulose, starch, lignin, water glass and the like can be used. These binder components may be used individually by 1 type, and may mix and use 2 or more types. Moreover, you may use 2 or more types of binders containing 1 type, or 2 or more types of binder components. In general, it is preferable to use a material that exhibits a thickening effect, or a combination of a material that exhibits a thickening effect and a material that exhibits a curing promoting effect.

  In the present invention, since the sintered raw material granulated by adding water and a binder is heated in the sintering process, the binder component is an inorganic substance rather than an organic substance that may be modified by a temperature rise. Is preferred. Among them, bentonite has a thickening effect and also has a moisture retention effect, and gradually releases moisture, so that the moisture evaporated at the top of the pallet during the sintering process is condensed at the bottom and prevents airflow resistance. It is thought that there exists and is preferable.

  Silica has almost no thickening effect, but when it contains a calcium ion source such as quicklime in the sintering raw material, it binds with calcium compounds such as slaked lime generated by the reaction of calcium ion source such as quicklime and water. In addition, since calcium silicate is generated and solidified, it exhibits an effect as a binder and is excellent in the stabilizing action of the pseudo particles. Therefore, a binder containing bentonite and silica is preferably used.

  As silica, water glass is generally used.

  The binder used in the present invention is particularly preferably an aqueous solution in which the binder component as described above is dissolved in water or dispersed in water for viscosity adjustment.

  Thus, the binder used in the present invention is prepared so that the funnel viscosity (500/500) measured by the above-mentioned method becomes 40 seconds or more by adding water to a binder component such as bentonite. It is preferable that When the funnel viscosity (500/500) of the binder is less than 40 seconds, the granulation effect may not be sufficient, and a granulated product having excellent pseudo particle formation properties may not be obtained. However, if the funnel viscosity (500/500) of the binder is excessively large, it becomes difficult to exert the effect of the binder on the entire raw material. Therefore, the funnel viscosity (500/500) of the binder is 300 seconds or less, particularly 40 to 150 seconds. Preferably there is.

  The amount of binder added to the sintering material varies depending on the type and concentration of the binder component used, but the amount of binder component added is 0.01 to 1% by weight, particularly 0.01 to 0.3%, based on the sintering material. It is preferable to set the amount so as to be weight%. In particular, when bentonite is added as a binder component, it is preferable to add bentonite so as to be 0.0005 to 0.3% by weight, particularly 0.007 to 0.07% by weight, based on the sintered raw material. . When silica is used in combination with bentonite, the silica is preferably added so as to be 0.0001 to 0.02% by weight, particularly 0.0003 to 0.003% by weight based on the sintering raw material.

  On the other hand, the amount of water added is adjusted so as to obtain a granulated product having a suitable water content described later.

  In the present invention, the binder is preferably an aqueous dispersion or aqueous solution prepared by adding water to a binder component such as bentonite, as described above, so that the amount of water in the binder is separate from the binder. The amount of water in the binder and the amount of water sprayed separately from the binder are appropriately adjusted so that a granulated product having a suitable moisture content described later can be obtained by the sum of the amount of water sprinkled, but is included in the binder. The ratio of the amount of water and the amount of water sprayed separately from the binder is such that the amount of water in the binder: the amount of water sprayed separately from the binder = 1: 0.1 to 10, particularly 1: 0.3 to 2. preferable. If the amount of water in the binder is larger than this range and the amount of water sprayed separately from the binder is small, the effect of improving the granulation effect by spraying water separately from the binder can be obtained according to the present invention. In addition, since the water content in the binder is large, the funnel viscosity (500/500) of the binder is reduced, and the granulation effect is inferior. Conversely, if the amount of water in the binder is small and the amount of water sprayed apart from the binder is large, the binder's water content is small, resulting in poor handling of the binder and the thickening action of the binder throughout the raw material. Since it becomes difficult to go around, the granulation effect is inferior.

  In the present invention, the binder and water are particularly the initial stage of granulation of the sintering raw material, that is, the period from the start to the end of granulation (the period required for this granulation is referred to as “granulation required time T”). )), That is, it is preferably added to the sintering raw material in a period (0 to 1 / 3T) of 1/3 of the granulation required time T from the start of granulation.

  In addition, the binder and water may be sprayed at the same time of the granulation required time or may be sprayed at another time, but when sprayed at another time, water spraying was started. Thereafter, it is preferable to spray a binder.

  In this invention, it is preferable that the moisture content of the granulated material obtained by granulation of such a sintering raw material shall be 6-9 weight%. Even if the moisture content is less than 6% by weight or more than 9% by weight, the granulation effect by the binder is reduced, resulting in a loss of economic efficiency.

  There are no particular restrictions on the mixer (granulator) used for granulation. In addition to the drum mixer, any mixer used for granulation of ordinary sintering materials such as bread mixers, Eirich mixers, paddle mixers, etc. can be applied. Is possible. The mixer may be a single-stage type or a two-stage series arrangement type.

  Below, with reference to FIG. 1 which shows typically an example of embodiment of the granulation method of the sintering raw material of this invention, the specific implementation method of this invention is demonstrated. In FIG. 1, members having the same functions as those shown in FIG.

  In FIG. 1, the drum mixer 4 is provided with a watering nozzle 5 for water addition and a spray nozzle 6 for binder addition on the inlet side. The sintering raw material from the blending tank 1 is charged into the drum mixer 4 from the belt conveyors 2 and 3, and granulated in the drum mixer 4 under the water spray from the water spray nozzle 5 and the binder spray from the spray nozzle 6. The obtained granulated particles are fed to a sintering machine through a subsequent surge hopper (not shown) and sintered to form a sintered ore.

  As described above, according to the granulation method of the sintering raw material of the present invention in which water is sprayed separately from the binder, granulated particles having excellent pseudo-particle property can be obtained. For example, good air permeability can be maintained in the sintering process, and a sintered ore can be obtained with high productivity.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

  In the following, the pseudo-particle property of the granulated particles was evaluated by a GI (pseudo-granulation) index.

The GI index is an evaluation method disclosed in the aforementioned Non-Patent Document 1 (Steel Manufacturing Research No. 288 (1976), pages 9 to 18), and the calculation formula is represented by the following formula. The larger the GI index compared to the blank, the smaller the amount of fine powder released and the better the pseudo-particle property. However, direct comparison is not possible if the blanks are different.
GI index = ((1−A ′ / A) + (1−B ′ / B)) × 100
A: Ratio (% by weight) of true particles having a particle size of 0.25 to 0.5 mm
A ′: Ratio of granulated particles having a particle diameter of 0.25 to 0.5 mm (% by weight)
B: Ratio of true particles having a particle size of 0.25 mm or less (% by weight)
B ′: Ratio of granulated particles having a particle size of 0.25 mm or less (% by weight)

Further, as bentonite, a slurry having a water weight of 2.5% by weight and a funnel viscosity (500/500) measured by the method described above was used as follows.
Bentonite A: Funnel viscosity (500/500) = 30 seconds Bentonite B: Funnel viscosity (500/500) = 43 seconds Bentonite C: Funnel viscosity (500/500) = 60 seconds Bentonite D: Funnel viscosity (500/500) = 100 seconds

Examples 1-6
Granulation was performed by the method shown in FIG.

  Sintering raw material (water content 4% by weight) with 1.5% by weight quick lime added to Australian iron ore “Saraji” is put into a drum mixer and granulated under water and binder spraying while rotating at 20 rpm. The granulated particles having a water content shown in Table 1 were obtained. Water and binder were sprayed over 1 minute from the start of rotation of the drum mixer, and the rotation time was 6 minutes. That is, water and binder were added during a period of 1 / 6T.

  As the binder, a water slurry of bentonite D, or a mixture having a composition and funnel viscosity (500/500) shown in Table 1 in which water glass (silicic acid No. 3) is further added to this, water sprayed separately from this binder is used. And the ratio of the amount of water in the binder was 1: 1, and the amount of each binder component added to the sintering material was sprayed so as to be the amount shown in Table 1.

  The obtained granulated particles were classified with a sieve, the GI index was examined, and the results are shown in Table 1.

Examples 7 and 8
Granulation was performed in the same manner as in Example 1 except that carboxymethylcellulose (CMC) or polyvinyl alcohol (PVA) was used instead of bentonite, and the GI index of the obtained granulated particles is shown in Table 1.

Comparative Examples 1-5
Granulation was performed in the same manner as in Example 1 except that water was sprayed so that granulated particles having a moisture content shown in Table 1 were obtained without spraying the binder, and the GI index of the obtained granulated particles. Is shown in Table 1.

Comparative Example 6
Granulation was carried out in the same manner as in Example 4 except that water was not mixed with the binder but water was mixed with the binder and sprayed as a single solution, and the GI index of the obtained granulated particles is shown in Table 1. Indicated.

  From Table 1, it is understood that granulated particles having a high GI index and excellent pseudo-particle formation properties can be obtained by spraying water separately from a binder made of a water slurry containing bentonite. In addition, since granulation is greatly influenced by the moisture content, it must be compared for the same moisture content.

  However, it is understood that when the moisture content of the granulated particles deviates from 6 to 9% by weight, the improvement effect by the binder cannot be sufficiently obtained, and it is preferable to obtain granulated particles having a moisture content of 6 to 9% by weight.

  Moreover, as a binder component, it is suitable to use bentonite, and it turns out that the further outstanding effect is acquired by using water glass for this together.

  Moreover, even if it uses a binder, when water is not sprinkled separately from a binder and the whole quantity of water is sprinkled with one binder and it spreads, it turns out that sufficient granulation effect is not acquired.

Examples 9-11
Granulation was performed in the same manner as in Example 4 except that bentonite A, B, C was used instead of bentonite D, and the GI index of the obtained granulated particles is shown in Table 2. Table 2 also shows the results of Example 2.

  From Table 2, it can be seen that it is preferable to use a binder having a funnel viscosity (500/500) of 40 seconds or more.

It is a schematic diagram which shows embodiment of the granulation method of the sintering raw material of this invention. It is a schematic diagram which shows a conventional method.

Explanation of symbols

1 Mixing tank 2, 3 Belt conveyor 4 Drum mixer 5 Watering nozzle 6 Binder spray nozzle

Claims (5)

  A method in which water and a binder are sprinkled and granulated on a sintering raw material containing iron ore and a calcium ion generation source, and the water is sintered by watering means provided separately from the binder spraying means. A method for granulating a sintering raw material, characterized by sprinkling water. The method for granulating a sintered raw material according to claim 1, wherein the binder has a funnel viscosity (500/500) measured by the following method of 40 seconds or more.
[Funnel viscosity (500/500) measurement method]
After adding 5 g of slaked lime to 500 ml of binder and stirring for 10 minutes, the funnel viscosity (500/500) based on API standards is measured.   3. The method for granulating a sintered raw material according to claim 1 or 2, wherein the obtained granulated product has a water content of 6 to 9% by weight.   4. The method for granulating a sintered raw material according to claim 1, wherein the binder contains bentonite.   5. The method for granulating a sintering raw material according to claim 1, wherein the binder contains bentonite and silica.

Images