JPS61113730A - Preliminary treating method of sintered raw material - Google Patents

Abstract

PURPOSE:To hold a reduced property of a sintered raw material, and to improve the reducing powdering resistance by mixing and pelletizing preliminarily an ore whose components are Al2O3, crystal water, Fe, CaO, and MgO, of a specified composition, and adding it to all sintered raw materials by a proper ratio. CONSTITUTION:An ore which has components of >=2.3wt% Al2O3 in total, >=2.1% crystal water, >=55% all Fe, <=5.0% CaO, and <=0.5% MgO, by compounding one kind or more of ores (a), (b), etc. containing a high alumina limonite, and also is constituted of a particle size of >=90% <=10mm grain size, and <=75% <=1mm is prepared, and it is mixed and pelletized preliminarily by a mixer 1 such as a pan-pelletizer, etc., and using a binder as necessary, and a pelletized product of >=65% 3-10mm particle size is formed. This pelletized product is added by 5-70% to all sintered raw materials, mixed and/or pelletized by a mixer 2, and the reducing powdering resistance is improved without deteriorating the reduced property of the sintered raw material. Said sintered raw material becomes a sintered ore by a sintering machine 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for pretreatment of sintering raw materials, and more particularly, to a method for pretreatment of sintering raw materials when high alumina limonite is used as a part of the raw materials. Regarding processing method.

(Prior art) Lime sintered ore with a high CaO concentration is widely used as a raw material charged into blast furnaces for producing pig iron, but in the Japanese steel industry, sintered ore with stable quality is used. In order to obtain iron ores, it is common to blend iron ores with various properties and use the mixture as a sintering raw material.

Among the iron ores that are blended in this way, high alumina limonite has various factors that adversely affect sinterability.In particular, as shown in Figure 2, high alumina limonite has various factors that adversely affect sinterability. A 120 : tends to deteriorate as the i component increases and the crystal water component increases. This is because in high alumina limonite, crystal water thermally decomposes and many pores are generated, resulting in carbon
High Al
This is due to the fact that zO3-containing calcium ferrite is easy to produce. Reduction pulverization of lime sintered ore occurs when hematite in the sintered ore is reduced to magnetite, generating expansion stress, and this stress destroys the forming matrix.
Calcium ferrite containing a large amount of AlzO3 is weak in strength and is extremely susceptible to reduction and powdering. The high alumina pyrite of interest in the present invention is A12032.3 wt.
% or more, water of crystallization (CW) 2. Owt% or more.

Many countermeasures and raw material processing methods have been proposed to address the above-mentioned factors that deteriorate the reduction powdering resistance of high alumina limonite. For example, in Japanese Patent Application Laid-Open No. 52-49905, instead of mixing and granulating various ore raw materials at once,
A method has been proposed in which the air permeability is improved by separately premixing and granulating only raw materials with poor granulation properties. In addition, Japanese Patent Application Laid-Open No. 57-79129 describes S of limonite ore and fine powder.
A method has been disclosed for improving the quality of sintered ore by pre-mixing and granulating it with an i 02- or Mg0Si02-based slag forming agent.

On the other hand, as for the method of granulating the sintering raw material, it has been known that a method of granulating fine iron ore using a pelletizer is extremely effective. This method of obtaining granules by growing nuclei from fine powder is extremely superior in terms of granulation properties.
However, it has the disadvantage of being extremely time consuming and low in productivity. In other words, there is the problem that the ore must be crushed into a fine powder, and it takes a long time for the raw material to reach the desired particle size for the product in order to perform nuclear growth from the fine powder. For this purpose, a nucleation granulation method has been disclosed, for example, in Japanese Patent Application Laid-Open No. 169023/1983.
ing. This method does not grow nuclei from fine powder, but instead tries to shorten the nucleus growth time by introducing coarse grains.The particle size distribution of the raw material is defined according to the target particle size product and the type of raw material. 0 (Problems to be Solved by the Invention) However, the first method among the above-mentioned conventional methods is mainly intended to improve air permeability, and is not suitable for improving the quality of sintered ore. has not arrived yet.

The second method is effective in improving resistance to reduction and pulverization, but since limonite reacts with high concentrations of 5iOz and MgO, minerals and slag with poor reducibility are formed. There is a problem that the reducibility of the entire ore decreases.

(Means for Solving the Problems) As described above, limonite ore with a high crystallization water content has good reactivity with CaO component, which is a solvent for producing sinter, and it is easy to produce calcium ferrite minerals. And Al12
Calcium ferrite containing a large amount of 03 is brittle and has poor reduction resistance. Therefore, in limonite containing high water crystallization, A
Those with a high 6zO+ content have poor resistance to reduction and powdering. The present inventors believe that in order to solve this problem, the reaction between high alumina limonite and CaO is suppressed, and high A11z03
Based on the knowledge that it is effective not to produce calcium-containing ferrite, we conducted extensive research and found that in order to suppress this reaction, we should coarsen the high-alumina limonite and produce calcium-containing ferrite.
It has been found that it is effective to isolate ores with a high O content, especially to reduce the CaO content of pre-granules (pseudo particles) to 5 wt% or less (Figure 5). To explain in more detail, high alumina limonite (in total, A12032.
As a result of conducting various experiments on CaO of 5 wt% or more, crystallization water of 2.1 wt% or more,
MgO is 0.5wt% or less, total Fe is 55wt%
Under the above component conditions and with a particle size of 10% or less, 90wt
If the premix granulation is carried out under the condition where the particle size is 75wt% or less and the particle size of the premix granulation product exceeds 65wt%, It has been found that the adverse effects of high alumina limonite can be eliminated, leading to the completion of the present invention.

If the particle size of the premixed granulated product is less than 3 mm, the reaction will not be suppressed, so it is desirable that the particle size is 3 mm or more. However, if the particle size exceeds 10 mm, it is not preferable because unevenness will occur during sintering and the yield will deteriorate (
Figures 3 and 4).

The MgO content of the premixed granulation product should be 0.5wt9f+ or less, as shown in Figure 6.
This is because if it exceeds wt%, the reducibility will deteriorate significantly. Furthermore, if the total Fe content in the granulated product is less than 55wt4, as shown in FIG. 65 w with a diameter of 3 to 10 mm
In order to obtain t% or more, the particle size composition of the raw material for the pre-mixed granulated product must be 10 mm or less.
It is appropriate that the amount of t4 or more and 1 silk or less is 75 wt % or less, but if the particle size of II + li or less exceeds 75 wt %, it will be extremely difficult to obtain the desired granule particle size.

In premix granulation, a binder may be used to improve the granule yield of particles with a particle size of 3 to 10.
High is preferable. The type of binder is pre-mixed granulation
If it satisfies the component conditions of the raw material,
It's okay to press. °
The granulator used for ore premix granulation may be of the drum type or pan pelletizer type. However, from the viewpoint of yield of granules with a particle size of 3 to 10 mm, a pan pelletizer type is preferable. t′1. obtained as above. fC
In the pre-mixed granulation product, pseudo-particles with a specific range of particle sizes are added to other coagulation materials and mixed granulation [
Ru. The amount of added premixed granulation product is in the range of 570 wt% based on the total sintered raw material. If the amount added is less than 5 wt%, the effect of addition is poor, and if it exceeds 70 wt, the content of CaO and MgO, which are necessary components of the blast furnace, is too low, and CaO and MgO are left in the blast furnace. The ingredients must be added.

An example of the flow of pretreatment of sintering raw materials according to the present invention is shown in FIG. 1a. In the example shown in FIG. 1a, two ores a+b containing alumina limonite are fed to a pelletizer, for example a pan pelletizer 1, and premixed and granulated in a pelletizer.

Here, the two types of stones a and b have Al2O3 as a whole.
．． Contains 3wt% or more and crystal water of 2.1wt1 or more,
The composition is selected and adjusted so that CaO is Owt'16 or less, MgO is (15wt4 or less), and daughter □Fe is contained more than 55wt%.A binder can be used in addition to ores a and b. The particle size of the mixed granulation raw material is 90wt or more for particles with a particle size of 10 or less, and particles with a particle size of 1 or less.
It is adjusted so that the amount below tar is 75 wt% or less.

The pseudo-particles premixed and granulated as described above are compared to other sintering raw materials, i.e., ore c+d having other properties, return ore e1 limestone f1 coke powder g, of all sintering raw materials. Mixer 2 is added in an amount of 5 to 70 wt%.
mixed and granulated. The obtained sintering raw material is charged into a sintering machine 3, and sintered ore is produced.

According to the present invention, instead of re-mixing and granulating the premixed granules with the remaining raw materials as shown in Figure 1a, as shown in Figure 1b, the premixed granulated raw materials a and b and the remaining raw materials are It is also possible to independently mix and granulate c = g and feed them directly to the sintering machine 3 in parallel. In this case, the sintering machine 3
The mixing phenomenon during the transportation process until it is loaded into the pallet is utilized.

(Example) A sintered steel test was conducted using the raw material properties shown in Table 1 under the compounding conditions shown in Table 2. The processing flow shown in FIG. 1b was used as the method of the present invention, and that shown in FIG. 9 was used as the conventional method. All other operating conditions were kept constant. The results are shown in Table 3.

Furthermore, nine experiments were conducted under the conditions shown in Tables 4 to 9. The results are shown in FIGS. 3 to 8.

In addition, what is indicated by n in parentheses in the recipe table is a premixed granulated raw material.

Table 1: Particle size and main components of the raw materials used in the test 2 Table 3: Comparison test results between the inventive method and the conventional method Table 4 (test conditions shown in Figure 3) Table 5 (test conditions shown in Figure 4) ) Table 6 (Test conditions in Figure 5) Table 7 (Test conditions in Figure 6) Table 8 Table 9 (Test conditions in Figure 8) <Use of pan pelletizer> (Effects of the invention) As mentioned above According to the present invention, the reactivity of high alumina limonite is suppressed without deteriorating reducibility, and high A
It is possible to suppress the production of calcium 7-elite containing 12O3 and improve resistance to reduction and powdering.

[Brief explanation of drawings]

Figures 1a and 1b are raw material processing flow diagrams according to the present invention, Figure 2 is a graph showing the relationship between the crystallization water, A, and g203 components of ore and reduction powdering resistance, and Figure 3 is a graph showing the relationship between the crystallization water, A, and g203 components of ore and reduction powdering resistance. A graph showing the relationship between particle size, reduction powdering, and product yield 9, Figure 4 is a graph showing the relationship between the ratio of 3 or more pseudo particles and reduction powdering, and Figure 5 shows CaO in the pseudo particles. A graph showing the relationship between concentration and reduction powdering, Figure 6 shows MgO in pseudo particles.
Graph showing the relationship between concentration and reducibility, Figure 7 is a graph showing the relationship between total Fe11 degree in pseudo particles and reducibility, Figure 8 is a graph showing the relationship between raw material dry particle size and pseudo particle size. , FIG. 9 is a conventional raw material processing flow diagram. 1, 2. 2', 2 ” ・ ・
Mixer-3...Sintering machine No. 10. (Fig. 1b, Fig. 2, Oshishui + CW)! ! ! 3! ! ! Pseudo particle size (front 1 Fig. 4 Fig. 5 Fig. 6 0 5 to 15
Mρ concentration in the pseudo particle C'l) C00 in the pseudo oni hand;

Claims (1)

[Claims] (1) When using high alumina limonite as part of the sintering raw material, the total amount of Al_2O_3 is 2.3wt.
% or more, crystal water is 2.1 wt% or more, total Fe is 5
5wt% or more, CaO 5.0wt% or less, MgO 0
．． Granulation using one or more types of iron ore having a particle size composition of 5 wt% or less, 90 wt% or more with a particle size of 10 mm or less, and 75 wt% or less with a particle size of 1 mm or less, and a binder if necessary. Product particle size 3-10m
Premix granulation is performed so that m is 65 wt% or more, and the resulting granulated product is 5 to 70 wt% based on the total sintered raw material.
A method for pre-processing sintered raw materials, characterized by adding % of the raw materials, mixing and/or granulating them.