JPH11181531A - Method for granulating sintering raw material and additive for granulation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the pseudo granulating properties of a raw material by executing granulation in such a manner that the surface tension of water and viscosity in a blending raw material contg. raw material powder ore, fuel and a solvent are adjusted. SOLUTION: It is preferable that, as an additive for granulation, a surfactant is used to adjust the surface tension of water, and the surface tension is preferably reduced by 5 to 40%. It is preferable that its viscosity is increased, and the additive for granulation in which natural high polymers are modefied into semisynthetic high polymers having hydrophilic radicals and hydrophobic radicals is used. As the semisynthetic high polymers, methylcellulose, ethylcellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropylethyl cellulose or the like are preferable. As for the amt. of the additive for granulation, it is preferably that, by weight to the blending raw material, the content of water is regulated to <=10%, and that of the additive for granulation is regulated to <=1%. In this way, uniform pseudo grains can be produced to remarkably improve the productivity in a sintering machine. Moreover, the large amount of coarse raw materials can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sintered ore used as a raw material for a blast furnace, and particularly to a method for adding water to a raw material ore for granulation, especially including a raw material ore, a solvent and a fuel. The present invention relates to a method for producing pseudo particles by granulating by adjusting the water content of a compounding raw material, and an additive thereof.

[0002]

2. Description of the Related Art In the production of sintered ore, first, iron ore, auxiliary materials, fuel, etc., which are blending raw materials, are mixed, and the mixture is formed while adjusting the water content with a granulator such as a drum mixer, a pelletizer, an Erich mixer. Granulate to make pseudo particles. The pseudo particles are particles in which fine particles of 0.5 mm or less are generally attached to core particles of 1 to 3 mm. At this time, what is required for the granulation is to improve the pseudo-granulation property in which the fine powder particles adhere around the core particles, that the pseudo particles hardly disintegrate in a wet zone, a dry zone, etc. in the firing process. . By using the pseudo-particles as the compounding raw material in this manner, the permeability in the sintering raw material packed layer on the sintering machine can be improved, and the productivity of the sintering machine can be improved.

[0003] For this purpose, conventionally, as a measure for improving pseudo-granulation properties, a method of adding various granulating additives as a binder to a compounding raw material has been proposed. Many are known as additives for granulation. For example, bentonite, lignin sulfite (pulp waste liquor),
Starch, sugar, molasses, water glass, cement, gelatin and the like have been studied for use as binders or thickeners. These have problems such as being expensive and difficulty in securing the amount to be used in the production of sintered ore, and are not used industrially.

[0004] Examples of granulating additives that are currently in practical use include, for example, Ironmaking Research No. 288 (1976), p9.
The quicklime disclosed in U.S.A. is widely used. According to this, by adding quick lime, firstly, pseudo-granulation in a mixer can be promoted, and secondly, a sintering material composed of pseudo particles is filled to a specific height, In the sintering process after igniting the surface layer after forming a tie bed,
It is said that the pseudo particles can be prevented from collapsing in the course of drying and heating, and a uniform air flow in the sintered layer can be maintained.

[0005]

Generally, the moisture content of the pseudo particles after granulation is adjusted to be in the range of 5 to 8 wt%.
Then, water is added through a nozzle or the like in the granulator to control the water content. However, since the blending material contains moisture, the amount of water to be added is 1 to 6 of the blending material.
It was difficult to uniformly granulate the quasi-particles while adjusting the water content of the raw materials to be constant, as low as about wt%. For this reason, irrespective of the presence or absence of the granulation additive, there were excessive granulation and insufficient granulation, and it was not possible to form sufficiently uniform pseudo-particles. Of course, the granulating additive could not be uniformly dispersed. The pseudo-particles with excessive granulation may not be fired inside the pseudo-particles at the time of firing, or may not be fired at the site where the basicity or the compounding component largely deviates from the design value. Further, in addition to the small particle size of the insufficiently granulated pseudo-particles, there is a problem that the airflow resistance in the raw material packed layer is increased by powdering on a sintering machine and the productivity is reduced. Was. Therefore, a method for producing uniform pseudo particles has been desired.

[0006] In addition, since the quick lime used at present is very expensive, it is presently operated with the usage amount reduced as much as possible. Then, even if 2% by weight or more of quicklime was added, the effect of improving the pseudo-granulation property tended to plateau. Furthermore, recently, there has been a problem that the ore fine ore has been severely degraded along with the depletion of the excellent lump ore, and the granulating property of the compounded raw material has been worse than before. For this reason, even if granulation is performed by adding quicklime, the effect is smaller than before. Therefore, it has been desired to develop an inexpensive granulating additive that replaces quick lime or a granulating additive that exhibits a productivity improving effect more than quick lime.

According to the present invention, when the pseudo-particles are granulated by adjusting the water content of the raw material powder ore, the solvent and the fuel, the properties of water are changed to achieve uniform pseudo-granulation. It is an object of the present invention to provide a granulating additive which improves pseudo-granulation properties, and further prevents the collapse of pseudo particles in a wet zone and a dry zone in a sintering process, and a method for granulating a sintering raw material.

[0008]

The granulating method and the granulating additive of the present invention are as follows.

(1) A method for granulating a sintering raw material, which comprises adjusting the water content of a raw material powder ore, a fuel, and a solvent and granulating the mixed raw material by adjusting the surface tension of the water.

(2) A method of granulating by adjusting the water content of a raw material powder ore, a fuel, and a solvent, wherein the surface tension and viscosity of the water are adjusted. Method.

(3) A method for granulating a sintering raw material according to (1) or (2), wherein the surface tension of water is adjusted by using a surfactant as a granulating additive.

(4) The sintering raw material according to (1) to (3), wherein a granulating additive is used which is a semi-synthetic polymer having a hydrophilic group and a hydrophobic group by modifying a natural polymer. Granulation method.

(5) The method for producing a sintering raw material according to any one of (1) to (4), wherein the water content is adjusted to 10% or less and the granulating additive is adjusted to 1% or less by weight% based on the compounding raw material. Grain method.

(6) An additive for granulating sintering raw materials, which is a semi-synthetic polymer comprising a cellulosic polymer having a hydrophilic group and a hydrophobic group.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the current granulator, the moisture brought in excluding crystallization water of the compounding raw material and the water contributing to granulation combining the water added in the granulator are uniformly dispersed in the compounding raw material. However, if this can be improved, pseudo-granulation properties can be improved. For this purpose, the surface tension of water may be reduced to prevent local accumulation of water. However,
If the surface tension is too low, the action of adhering the fine powder particles around the core particles is too low due to the surface tension of water, so that the surface tension has not been reduced so far. FIG. 1 shows the particle size distribution of the pseudo particles and the distribution of the true particle size obtained by completely drying the pseudo particles. As described above, by slightly lowering the surface tension of the water to be added, water can be uniformly dispersed, and the ratio of particles having a diameter of 1 mm or less is greatly reduced without lowering pseudo-granulation properties, thereby forming pseudo particles. It was discovered through various studies that granulation was possible. Here, the surface tension of water is generally about 70 × 10 ⁻⁵ N / cm, but in the present invention, it is desirable that the surface tension is in a range where the surface tension is reduced by 5 to 40%.

The means for reducing the surface tension of water is not particularly limited, but the surface tension can be easily reduced by adding a surfactant. As a method of addition, for example, if the surfactant is in a powder form, it may be mixed with the raw material to add quicklime and granulated, or water in which the surfactant is dissolved may be added. Alternatively, both methods may be combined. The surfactant is not limited to an anion, a cation, an amphoteric surfactant and the like.

It is conventionally known that pseudogranulation properties are improved by increasing the viscosity of water using a granulating additive or the like. Addition of a granulating additive that increases the viscosity of water to the granulating additive that lowers the surface tension of water as described above allows uniform pseudo-particles to be granulated,
The pseudo particle strength can be improved. However, simply increasing the viscosity of water has an adverse effect of hindering the dispersion of water, and thus promotes non-uniform granulation, and in particular, can increase the amount of excessively granulated mass. Therefore, in order to improve the pseudo-granulation property by increasing the viscosity of water, it is necessary to uniformly disperse water, and it is necessary to reduce the surface tension of water as described above. .

Further, as a granulating additive that decreases the surface tension of water and increases the viscosity of water more than ever by adding a small amount, it has a hydrophilic group and a hydrophobic group by modifying a natural polymer. If a granulating additive made of a semi-synthetic polymer is used, pseudo-granulation can be improved with only the granulating additive. Furthermore, the pseudo-granulation property can be controlled in combination with other granulating additives such as a surfactant and quicklime. Furthermore, even if the semi-synthetic polymer is dried once after dissolving in water to increase the viscosity of the water, the polymer fiber remains in a film shape, and thus has a bonding force even after drying. Therefore, in the raw material packed layer on the sintering machine, the disintegration of pseudo particles is generally caused in the dry zone. However, since the semi-synthetic polymer can prevent the disintegration of the pseudo particles, the air flow resistance in the dry zone is higher than before. , And a combustion-melting reaction of pseudo particles in an ideal state more than before.

As the semi-synthetic polymer having a hydrophilic group and a hydrophobic group obtained by modifying a natural polymer, methylcellulose, ethylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose and the like are preferable from the viewpoint of increasing the viscosity of water. Particularly, methylcellulose and carboxymethylcellulose are preferable for industrial use from the viewpoint of cost and production amount.
Further, since these can be made into a powder form, they may be mixed with the blended raw materials and granulated, or may be dissolved in water, so that water in which the semi-synthetic polymer is dissolved in advance may be added. Can also be combined.

The amount of the granulating additive to be added is preferably 10% or less, and the amount of the granulating additive is preferably 1% or less in terms of% by weight based on the raw materials. If the amount of the additive for granulation is more than 1%, the surface tension of the surfactant is too low to deteriorate the quasi-granulation property, and the semi-synthetic polymer is excessively granulated to form a mass. There is an adverse effect such as no firing. The lower limit is
Although it depends on the granulation properties of the ore as the compounding raw material, the amount of water added, the granulator used, and the like, it is desirable to design the ore as small as possible.

[0021]

EXAMPLES The present invention will be described in more detail with reference to Examples 1, 2, and 3.

Table 1 shows the mixing ratios of the mixing raw materials used in this experiment. The compounding raw materials are various iron ores and limestone, quicklime, serpentine, and scale as sinter in the ore as various raw materials.
O ₂ and Al ₂ O ₃ were adjusted to 5.8% and 1.8%, respectively, and the basicity was adjusted to 1.7.
The returned ore blending ratio was constant at 15 wt% with respect to the new raw material, and the coke blending ratio was constant at 4.0 wt% with the new raw material. The comparative examples and the examples have the same composition. In addition, the addition ratio of the granulating additive shown below is shown in% by weight with respect to the new raw material.

[0023]

[Table 1]

After mixing the returned ore and the coke breeze into the raw materials, water was added, mixed with a drum mixer, granulated, and charged into a sintering machine. The amount of water added by the granulator was adjusted so that the water content of the blended raw material (pseudo particles) after granulation was constant at 6.7 wt%. In the operation, the layer thickness was kept constant at 550 mm, the suction negative pressure was kept constant at 1500 mmAq, and the pallet speed was adjusted so that the sintering completion point was located in the mining part.

In Example 1, sodium alkylallyl sulfonate was added as a surfactant in advance to the water added by the mixer in an amount of 0.01 wt% with respect to the water after granulation of the raw material (based on the water of the pseudo particles). And granulated. The surface tension of the water after granulation was 20 compared to Comparative Example 1.
% Decreased.

In Example 2, granulation was performed by adding methylcellulose, which is a powder, as a semi-synthetic polymer to the compounding raw material so as to be 0.1 wt% with respect to the compounding raw material. Methyl cellulose is a 2% aqueous solution and has a viscosity of 150,000 mP.
The viscosity of the water after granulation was increased by 50% and the surface tension was 10
% Decreased.

In Example 3, sodium alkylallyl sulfonate was added as a surfactant in advance to the water added by the mixer in an amount of 0.01 wt% with respect to the water after granulation of the raw material (based on the water of the pseudo particles). Was added as follows. Further, powdered methylcellulose as a semi-synthetic polymer was added to the compounding raw material so as to be 0.1 wt% with respect to the compounding raw material, and granulation was performed. The methylcellulose used had a viscosity of 150,000 mPa · s in a 2% aqueous solution. Here, the surface tension of the water after granulation was reduced by 20% compared to Comparative Example 1, and the viscosity of the water after granulation was increased by 50% compared to Comparative Example 1.

In Comparative Example 1, granulation was performed by adding only water to the same compounding raw material as in the example.

In Comparative Example 2, 1% by weight of quick lime was added to the same blended raw material as that of the Example, and the quick lime and the new raw material were combined.
It was added and granulated.

Table 2 shows the GI index and the average particle size of the pseudo particles obtained in Comparative Examples 1 and 2 and Examples 1, 2 and 3, the production rate of sinter, product yield, RDI, and NOx emission basic unit. Is shown.
In addition, the GI index of the pseudo particle is referred to as Ironmaking Research No. 288 (1976), p9. Is shown in FIG. 2, and the calculation method is shown in FIG.

[0031]

[Table 2]

As can be seen from Table 2, Examples 1, 2, and 3
As compared with Comparative Examples 1 and 2, the GI index of the pseudo particles was remarkably improved, the average particle size was also increased, and the production rate and the product yield were improved. Further, conventionally, when the production rate is improved, the product yield tends to decrease, but in the embodiment, the product yield is improved. In addition, the reduction and crushing index (RDI) of the sinter was improved, the basic unit of NOx emission was reduced, and excellent operational and environmental effects were exhibited.

The method and amount of the granulating additive,
The addition ratio and the granulation method are not limited to those in the above examples.

[0034]

According to the present invention, it is possible to improve the pseudo-granulation property, which has been difficult in the past, to produce uniform pseudo-particles, and to greatly improve the production rate of a sintering machine. Further, it is possible to improve product yield, RDI and NOx emission intensity. As described above, the present invention brings about an incompatibility improvement effect at the same time, and the effect is very large, for example, a large amount of inferior raw materials can be used.

[Brief description of the drawings]

FIG. 1 is a diagram showing examples of pseudo particles and true particle sizes.

FIG. 2 is a diagram illustrating a method of calculating a GI index of a pseudo particle.

Claims (6)

[Claims] 1. A method for granulating a sintering raw material, comprising adjusting the water content of a raw material powder ore, a fuel, and a solvent and granulating the mixed raw material, wherein the surface tension of the water is adjusted. 2. A method of granulating by adjusting the water content of a raw material powder ore, a fuel, and a solvent, wherein the surface tension and viscosity of the water are adjusted. . 3. The method for granulating a sintering raw material according to claim 1, wherein the surface tension of water is adjusted by using a surfactant as a granulating additive. 4. The sintering method according to claim 1, wherein an additive for granulation is obtained by modifying a natural polymer into a semi-synthetic polymer having a hydrophilic group and a hydrophobic group. Granulation method of raw material. 5. A water content of 10% by weight based on the blending raw material.
The method for granulating a sintering raw material according to any one of claims 1 to 4, wherein the granulating additive is adjusted to 1% or less and the granulating additive to 1% or less. 6. An additive for granulating a sintering raw material, which is a semi-synthetic polymer comprising a cellulosic polymer having a hydrophilic group and a hydrophobic group.