JPS5983727A - Preparation of iron ore stock material to be sintered - Google Patents

Abstract

PURPOSE:To attain to enhance the JIS reduction ratio and the reduction powdering index of a sintered ore, by obtaining a stock material to be sintered by mixing a granulated stock material to be sintered not contributing to the formation of calcium ferrite during sintering, limestone with a proper particle size and a powdery ore. CONSTITUTION:An iron ore powder forming calcium ferrite during sintering, limestone having particle size distribution wherein 70% or more is 1-3mm., pref., 10% or less is 3-5mm. and a fine particle with a particle size of -1.0mm. is 20% or less and a return ore are compounded in a first mixer. On the other hand, stock materials to be sintered each not contributed to the formation of calcium ferrite during sintering such as an iron ore powder, a silica sand powder or serpentinite are compounded with water, a binder or the like in a disc pelletizer to be granulated. Subsequently, the above mentioned granulated material and the stock material of the first mixer and mixed and granulated in a second mixer to obtain an iron ore stock material to be sintered wherein the above mentioned granulated material 1 and coarse particulate limestone 2 are dispersed in the powdery ore 3 so as to be coated with said powdery ore 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve the JIS reduction rate and reduced powdering index (RD I). The present invention relates to a method for producing a raw material for sintering iron ore.

The quality of sintered ore charged into a blast furnace depends on the development of blast furnace operating conditions,
Due to changes in the raw material situation, it is not enough to control the strength at room temperature alone, and recently it has become important to control the properties when undergoing heat reduction in the blast furnace, that is, the Jr8R element ratio and the reduction pulverization index (DI). It has become.

In order to improve the JIS reduction rate, K reduces magnetite in the mineral structure of the sintered ore, and reduces calcium.

It is necessary to generate a large amount of ferrite.

It was also expected that in order to improve the reduction index, it would be necessary to reduce secondary hematite generated during the sintering process.

Conventional measures to improve the JIS reduction rate and reduction pulverization index (R, DI) include adjusting the amount of slag in the sintered ore;
Controlling IfigO in sintered ore by increasing or decreasing the blending ratio of coke powder, At203 @T 10 in raw materials
．． 2. Efforts have been made to adjust the amount of PMgO and to control the amount of ventilation during sintering, but sufficient results have not always been obtained.

For this reason, the applicant has improved the JISi yuan rate.

As a measure to improve the reduction pulverization index, the particle size of limestone in the blended raw materials should be adjusted to 1 to 3 particles, preferably the total amount, at least 50% or more, and inevitably, 3 to 5 particles to be 10% or less, and/or We are currently proposing a method for producing sintered ore in which the particle size of -025m fine particles is adjusted to 19% or less and mixed into the sintering raw material.

and a granulated material that is pre-granulated with a sintering raw material that does not contribute to the production of calcium and ferrite during sintering, and a sintered raw material that produces calcium and ferrite during sintering, including limestone granules. Calcium is used as a sintering raw material during sintering. A method is currently being proposed in which a large amount of ferrite is produced and the production of secondary hematite is significantly suppressed. However, although these methods have been improved over previously known methods, they do not necessarily produce the ideal results for the reasons described below.

In other words, in the former method, limestone is uniformly mixed with other blended raw materials, so limestone particles have a high concentration of 5j02 in the blended raw materials.
It easily contacts particles and forms 810□ with CaO during the sintering temperature raising process.
A reaction site is created, and therefore CaO and pA'203
The amount of reaction decreases, and the production of calcium and ferrite is insufficient, and secondary hematite is also produced.

In the latter method, since the high 5102 ore and limestone are granulated, there is less contact between the limestone particles and the high 5 ioz particles compared to the former method.

However, calcium during sintering. Because granulated limestone is used as the limestone in the sintering raw material that produces ferrite, the granulated limestone in the blended raw material partially collapses due to excess moisture during the water condensation process during the sintering process, forming granulated limestone. Fine-grained limestone becomes present in the blended raw material.

For this reason, as this fine limestone decomposes at an early stage of the sintering process, OaO reacts with 5io2 in the raw materials that produce calcium and ferrite, or with 8102 in the raw materials that do not contribute to the production of calcium and ferrite, and the part that forms silicate slag. arise. Therefore, the production of calcium and ferrite is suppressed.

It also generates secondary mattite.

Therefore, although both the JIS reduction rate and reduction powdering index are improved compared to those known up to now, the improvements are still far from sufficient.

Therefore, the present inventors conducted research on suppressing the formation of secondary hematite during sintering and generating large amounts of calcium and ferrite, and conducted investigations and studies using test sintered steel. As a result, it was found that the generation or growth of secondary hematite can be controlled by delaying the reaction of limestone in the sintering compound raw material during the sintering process.

This is because the reaction of CaO is suppressed in the first half of the sintering process, and when the atmosphere in the system becomes hostile in the second half of the sintering process, Fe2O3 and OaO are actively reacted to form calcium. This is an attempt to suppress the generation and growth of secondary matite by generating ferrite.

For this reason, it is necessary to suppress the reaction of OaO in the F'eO-5i02-CaO system melt, for example the reaction of CaO in the first half of the sintering process.

Therefore, the present inventors further developed the above knowledge and developed a raw material and calcium that generate calcium and ferrite during sintering. In addition to separating the raw materials that do not contribute to ferrite production, the calcium and limestone in the raw materials that produce ferrite have a particle size of 1 to 3 sm, preferably the total amount, at least 7 sq.
If the calcium is 0% or more and unavoidable, the particle size is adjusted to 3-5 times less than 10%, or -1.0m fine particles less than 20%. It has been found that the production of secondary hematite can be significantly suppressed by producing a large amount of ferrite.

This is better than what the applicant is proposing, since CaO and 81
Almost no reaction of 02 takes place, and most of the aaO is FJ.
I found out that this is because it reacts with '203 fC.

The present invention was completed based on such knowledge.
The aim is to provide a method for producing iron ore sintered raw material for producing sintered ore with excellent reduction rate and reduction powdering index.

In order to achieve the above object, 1 the present invention uses a granulated material pre-granulated with a sintering raw material that does not contribute to the formation of calcium and ferrite during sintering, and a grain size of 1 to 3 m, preferably in full view, at least 70% or more, and unavoidable. Calcium at the time of sintering, including limestone with 10% or less of 3-5m particles and 20% or less of -1° Omm fine particles. The present invention provides a method for producing an iron ore sintering raw material, characterized in that the iron ore sintering raw material is mixed with a sintering raw material that produces ferrite.

More details on calcium. When granulating a sintering raw material that does not contribute to the formation of ferrite, b51 As already proposed by the present applicant, the moisture content is 4 to 9%, and the grain size of the granulated material is 20% of 1 knot or less.

Adjust so that 5I+IwI or more is 50% or less.

In addition, specifying the particle size of limestone in the raw material that produces calcium and ferrite during sintering as described above is because if the 3-5 mass exceeds 11%, there will be parts where the decomposition reaction of limestone will not take place, resulting in ineffective results. It is small or the normal temperature properties of the sintered ore deteriorate,
Furthermore, when the amount of -1, Onrs fine particles exceeds 21%, the effect becomes smaller at fc.

The present invention will be explained below based on the drawings.

FIG. 1 shows an example of the present invention.

First, add calcium to the first mixer. The basicity (OaO/
Blend so that S 102 ) is 1.3 to 20.0.

The return ore is mixed into the first mixer in the normal process.

Next, calcium is sintered into a granulator such as a disk pelletizer. A sintering raw material 1 that does not contribute to the formation of ferrite, such as a mixture of powdered ore, silica stone, serpentine, etc., and water are blended, and if necessary, a binder such as bentonite is blended, and then granulated.

In this case, silica stone, serpentine, etc. do not need to be mixed with powder ore and granulated, but silica stone and serpentine may be granulated individually or as a mixture thereof.

Furthermore, if silica stone or serpentine is received in a particle size of 1 to 5 mm, which hardly reacts with CaO, granulation is not necessary.

In this case, silica and serpentine may be mixed in the first mixer.

Next, the above granulated material and the raw materials from the first mixer are blended into a second mixer and mixed and granulated.

In addition, when mixing and granulating in the above first and second mixers,
Coke and water are mixed together using a normal process and used as a sintering raw material.

As schematically shown in Figure 2, the sintering raw material produced in this way consists of a granulated material 1 that does not contribute to the production of calcium and ferrite during sintering, and a coarse material mainly consisting of fins 1 to 3. The granular limestone 2 is coated with the fine ore 3 that produces calcium and ferrite during sintering, and is dispersed in the fine ore 3.

Therefore, when the sintering raw material is sintered using a sintering machine, the sintering raw material becomes calcium during sintering. Sintered raw materials that produce ferrite, and calcium. Powdered ore that is separated into raw materials that do not contribute to the formation of ferrite, and the raw materials that do not contribute to the formation of calcium and ferrite are granulated, and at the same time, the surface of the granules produces calcium and ferrite during sintering. and that it is coated with calcium. The limestone in the raw material that generates ferrite mainly has a grain size of 1 to 3 fins, and at the same time, the surface of the limestone is encapsulated by powdered ore that generates calcium and ferrite during sintering, so the reaction between OaO and 8102 occurs. However, most of the aaO reacts with Fe'203 to produce large amounts of calcium and ferrite, and the production of secondary hematite is greatly suppressed.

Therefore, the JIS reduction rate and reduction powdering index of the sintered ore are significantly improved.

Examples of the present invention are shown below along with comparative examples.

EXAMPLE As sintering raw materials that do not contribute to the formation of calcium or ferrite, 1 to 5 m of ore powder, 1 to 5 m of silica powder, and 1 to 5 m of serpentine powder were prepared.

calcium. As raw materials for producing ferrite, limestone, Yanby ore powder, Pailadeira ore powder, and Boa powder ore were prepared.

Table 1 shows the respective formulations, ingredients, and particle sizes excluding limestone.

The particle size of limestone is shown in Table 2. (Example of the present invention, others are comparative examples) First, Hamasley powder ore was granulated by adding water using a disc pelletizer. The properties of granulated Masley ore are as follows:
Shown in the table.

Next, raw materials other than the granulated Hamasley ore were mixed and granulated using a mixer with the addition of water in the mixing ratios shown in Table 1.

This 1iiJ limestone is made of 8 types of limestone listed in the RF42 table separately for 1 month, 1 year, 1 day, 1 ζ0.Then, the above 1 grain Hamasley ore and other mixer mixed raw materials are charged into a 1f) degree mixer, and mixed and granulated. did. Incidentally, coke was mixed based on a normal process and a sintering test was conducted.

After sintering, the falling frequency, JIS reduction rate, and reduction powdering index were measured.
It was fixed at 11.

For comparison, instead of the VC% ashstone shown in Table 2 above, normal grained limestone shown in Table 4 was granulated using a disc pelletizer, and sintering was also carried out by blending shield grained limestone as shown in Table 5. .

A! It is shown in Table 6.

Table 2 Table 6 Figure 3 shows the sintering test results.

From this figure, it can be seen that in Experiments 1 to 4 of the present invention, the drop strength was actually maintained the same as that of Experiment 9, and J l
It can be seen that both the SR rate and the reduction powdering index are much improved compared to the method of Experiment 9.

In comparison, in Experiments 5 to 8, which are comparative examples, the JIS reduction rate, reduction powdering index, drop strength, etc. were worse than in Experiment 9.

As explained above, by processing raw materials and producing sintered ore as in the present invention, calcium is added to the sintered ore compared to conventional sintered ore. Since a large amount of ferrite is produced, when this sintered ore is used for one to one time with a surface furnace, it is difficult to produce because there is little reduction and powdering, so it has good air permeability, and also has excellent reducibility. +qt can be increased, and this invention has great industrial value.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an example of the raw material processing method of the present invention, Fig. 282 is a schematic explanatory diagram of the sintering raw material of the present invention, and Fig. 3 is a drop strength!
, JIS reduction rate, and reduction powdering index. ■ is calcium during sintering. Granules of sintering raw materials that do not contribute to the production of ferrite, 2 is limestone, and 3 is calcium during sintering. Fine ore that produces ferrite. Instead! People Patent Attorney Masaaki Akizawa Mitsunobu 2 Nai 1m Kubiotzu Well 3 days

Claims (3)

[Claims] (1) Pre-granulated sintering raw materials that do not contribute to the production of calcium and ferrite during sintering, and calcium and ferrite during sintering containing limestone with grain size 1 to 3 of 70% or more A method for producing an iron ore sintering raw material, characterized by mixing the iron ore raw material with a sintering raw material to obtain a sintering raw material. (2) A method for producing an iron ore sintering raw material, which is based on the method described in claim 1, and uses limestone having a particle size of 3 to 5 grains of 10% or less as a sintering raw material. (3) A method for producing an iron ore sintering raw material in which limestone containing 20% or less of fine particles with a particle size of -1.0 ml is mixed as a sintering raw material in the method according to claim 1 or 2.