JP2006152334A - Method for producing sintered ore - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a high-quality sintered ore with high strength at a high yield even if ore containing much phosphorus is blended in a raw material to be sintered, and even if ore containing much Al<SB>2</SB>O<SB>3</SB>like the ore containing much phosphorus is used as the raw material. <P>SOLUTION: The method for producing the sintered ore uses a mixture of iron ore and lime stone as a raw material, wherein the iron ore contains 2.0 mass% or more Al<SB>2</SB>O<SB>3</SB>at least as one part and has an average particle diameter of 2.0 mm or smaller, and the limestone has an average particle diameter of 2.0 mm or larger, and contains 15 mass% or less fine particles with a particle diameter of 0.25 mm or smaller. The iron ore containing 2.0 mass% or more Al<SB>2</SB>O<SB>3</SB>and having an average particle diameter of 2.0 mm or smaller preferably contains 0.1 mass% or more of P. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a sintered ore used as a main raw material for a blast furnace or the like.

  Sinter ore, which is the main raw material of the blast furnace ironmaking method, is generally manufactured as follows. First, an iron ore powder having a particle size of 8 mm or less and a mass average diameter of 2.0 to 4.0 mm, limestone adjusted to a particle size of 3.0 mm or 5.0 mm, CaO-containing raw materials (hereinafter referred to as CaO-containing auxiliary materials) ), Granulation aids such as iron mill recovered powder, sintered ore sieving powder, quick lime, and carbonaceous materials such as coke powder and anthracite at a predetermined ratio while mixing with a drum mixer, etc. After adding water and adjusting the humidity, the mixture is granulated with a drum mixer or a disk pelletizer to produce pseudo particles having an average diameter of 3.0 to 6.0 mm. The pseudo particles are placed on an endless moving type sinter pallet. Fill to a height of around 400-600 mm and ignite the charcoal on the surface layer of this packed bed. The carbonaceous material is burned while sucking air downward, and the raw material pseudo particles are sintered by the combustion heat generated at that time to obtain a sintered cake. The obtained sintered cake is crushed and sized, and agglomerated 3 to 5 mm or more is used as a product sintered ore, which is charged into a blast furnace and used.

In a sintering machine, Fe-containing raw materials such as fine iron ore are agglomerated mainly because quick lime in contact with iron ore, CaO in limestone reacts with iron oxide and has a low melting point CaO-Fe ₂ O. _{This is because a three-system} melt is formed, and agglomeration is performed through this melt, and at the same time, various structures constituting the sintered ore are crystallized and formed.

It is also known that this melt, which plays an important role in the sintering reaction, is the starting point of fine particle contact between iron ore, quicklime and limestone. Furthermore, when Al ₂ O ₃ is dissolved in this initially generated melt, the viscosity becomes high, the fluidity is deteriorated, and the sintering reaction between the ores does not proceed sufficiently, so that the yield and strength of the sintered ore are deteriorated. (For example, refer nonpatent literature 1 and nonpatent literature 2.).
Inoue, Ikeda et al. “Iron and Steel” 68, 1982, p. 2190 Kawaguchi, Kasama, Inatsumi “Iron and Steel” 78, 1992, p. 1053

  Conventionally, hematite ore (hematite) and magnetite ore (magnetite) have been mainly used as raw iron ore for sintered ore, but recently the supply of such high-quality iron ore is decreasing, There is a pressing need to use iron ore with a high water content or iron ore with a high P (phosphorus) content.

High phosphorus ore has a higher P content than ordinary powdered iron ore used as a sintering raw material, and is generally an iron ore containing 0.1 mass% or more of P. Using such iron ore with a high P content as a blast furnace raw material increases the P concentration of the hot metal to be produced and increases the load of dephosphorization treatment. . However, since the supply amount of high-quality iron ore is decreasing as described above, it is being studied to add a considerable amount of this high phosphorus ore as a sintering raw material. However, as a result of studies by the present inventors, it has been found that when high phosphorus ore is used as a sintering raw material, there is a problem that the strength and yield of the sintered ore deteriorate. This is probably because the high phosphorus ore has a high Al ₂ O ₃ content.

  Therefore, the object of the present invention is to solve such problems of the prior art and to produce a high-quality sintered ore with high strength and yield even when blending high phosphorus ore into a sintering raw material. It is to provide a manufacturing method.

Another object of the present invention is to produce a high-quality sintered ore with high strength and yield even when a raw ore having a high Al ₂ O ₃ content such as a high phosphorus ore is used. It is to provide a manufacturing method.

The features of the present invention for solving such problems are as follows.
(1) A method for producing a sintered ore from a sintering raw material in which iron ore and limestone are blended, wherein the iron ore contains at least part of Al ₂ O ₃ in an amount of 2.0 mass% or more and an average grain A sintered ore comprising iron ore having a diameter of 2.0 mm or less, wherein the limestone has an average particle size of 2.0 mm or more and a content of fine particles having a particle size of 0.25 mm or less is 15 mass% or less. Production method.
(2) The iron ore containing Al ₂ O ₃ in an amount of 2.0 mass% or more and having an average particle size of 2.0 mm or less contains P in an amount of 0.1 mass% or more in (1) The manufacturing method of the sintered ore as described.

According to the present invention, a high-quality sintered ore with high strength and yield can be produced even when a raw ore having a high Al ₂ O ₃ content is used. In particular, high-phosphorus ore can be effectively used as a raw material for sintered ore to produce a high-quality sintered ore with high strength and yield.

  Table 1 shows the types of main iron ore resources and their compositions.

According to Table 1, it can be seen that the high-phosphorus ore has a smaller average particle size and a higher Al ₂ O ₃ content as compared with a normal fine iron ore used as a sintering raw material. Further, as a result of investigations by the present inventors, it has been found that the high phosphorus ore has a high Al ₂ O ₃ content particularly in fine grains. For example, the Al ₂ O ₃ content of high-phosphorus ores having a particle size of 0.063 mm or less may be about twice that when a plurality of types of iron ores that are normally used are mixed. For this reason, the contact frequency (ratio) with limestone increases compared with normal ore, and most of the initial melt formed at the time of firing dissolves a large amount of Al ₂ O ₃ and flows from around the high phosphorus ore. It is considered that the sintering reaction through the generated melt in the entire bed of the sintered bed does not proceed sufficiently and deteriorates the strength and yield of the sintered ore.

Therefore, in the present invention, in order to solve the above problems and to effectively use high-phosphorus ore as a sintering raw material, the contact ratio between Al ₂ O ₃ and limestone is reduced and Al ₂ O dissolved in the melt is dissolved. A method of reducing the amount of ₃ was examined, and it was found that it was effective to increase the particle size of limestone than that conventionally used. For this purpose, the limestone needs to have a particle size distribution in which the proportion of fine powder having a particle size of 0.25 mm or less is 15 mass% or less. In order to obtain such a particle size distribution, the average particle size of limestone is 2.0 mm. It has been found that it is effective to obtain the above particle size distribution.

  In addition, about the quicklime containing CaO similarly to limestone, since it reacts with water or warm water at the time of sinter ore production and the ultrafine particle of calcium hydroxide is produced, adjusting the particle size has no effect.

If the particle size of limestone is adjusted as described above, the contact ratio between limestone and high phosphorus ore is relatively lowered. Further, if the particle size of the limestone that comes into contact is relatively large, even if a reaction occurs, the concentration of the Al ₂ O ₃ that dissolves is large compared to the case of using limestone of the conventional particle size because the amount of CaO is large. Therefore, the fluidity of the melt can be secured and the sintering reaction can be sufficiently advanced.

The above principle can be applied to all ores having a high Al ₂ O ₃ content and a relatively small average particle size as in the case of high phosphorus ores, and at least a portion of the raw material ore contains Al ₂ O ₃ of 2.0 mass% or more. This is effective when iron ore having an average particle diameter of 2.0 mm or less is used as a raw material for sintered ore, but the Al ₂ O ₃ content is particularly high in the fine granules, and the P content is 0.00. When high phosphorus ore having 1 mass% or more and Al ₂ O ₃ content of 2.0 mass% or more is used, the strength and yield of the sintered ore are greatly improved. At least a portion of the ore to be blended is containing Al ₂ O ₃ or 2.0 mass%, and the average particle size is the effect of the present invention as long as the following iron ore 2.0 mm, the Al ₂ O ₃ When iron ore containing 2.0 mass% or more and having an average particle size of 2.0 mm or less is blended in an amount of 5 mass% or more of the total blended raw materials of sintered ore, the effect of improving the strength and yield of the sintered ore is obtained. it is obvious.

  As a particle size adjustment method for increasing the particle size of limestone, it is effective to remove fine powder, for example. Usually, limestone stored outdoors has a water content of at least 3 mass%, and if it is large, about 5 mass%. Since it contains, it is difficult to remove a fine powder by simple methods, such as a sieve. Therefore, it is not a practical method to reduce the proportion of fine powder having a particle size of 0.25 mm or less to 15 mass% or less by removing fine powder having a particle size of 0.25 mm or less. As another simpler means, for example, reviewing the management specification of the particle size of the limestone used, relaxing the upper limit control value of the particle size and lowering the proportion of fine powder is effective without increasing costs. Means. Table 2 shows an example of the particle size distribution when the upper limit control value of the particle size of limestone used as a normal sintered ore raw material is changed.

  As shown in Table 2, when the upper limit of the particle size of limestone is controlled to 5 mm (−5 mm), the average particle size is 1.74 mm, but when the upper limit of the particle size of limestone is managed to 7 mm (−7 mm). ) Has an average particle diameter of 2.11 mm. Thus, it is possible to control the average particle size by managing the upper limit value of the particle size of limestone. The proportion of fine powder having a particle size of 0.25 mm or less can also be made 15 mass% or less by managing the upper limit of limestone to 7 mm.

  As shown in Table 3, to the sintered raw materials (Comparative Example 1, Comparative Example 2, Invention Example 1, Invention Example 2), 4.0 mass% of powder coke was added as a carbon material and mixed. Post-humidification and granulation were carried out, and the granulated particles were introduced into a pan having a diameter of 26 cm so as to have a layer thickness of 400 mm. After the surface was ignited with a burner, a firing test was performed at a constant suction pressure of −10 kPa. In Comparative Example 1 and Comparative Example 2, limestone (-5 mm in Table 2) with an upper limit of the particle size of 5 mm was used. On the other hand, in Inventive Example 1 and Inventive Example 2, limestone (-7 mm in Table 2) with an upper limit of particle size of 7 mm was used.

  The productivity, tumbler strength, yield, RDI, and RI of the sintered ore produced in the firing test were measured. The results are shown in Table 4.

  Comparing Comparative Example 2 and Invention Example 1 where the blending amounts of the raw materials are the same, it can be seen that productivity, strength, and yield are improved by making the particle size of limestone coarse.

  Moreover, in Example 2 of this invention, it turns out that productivity and intensity | strength of a sintered ore are maintained, although the compounding rate of a high phosphorus ore is as high as 8 mass%.

Claims (2)

A method for producing sintered ore from a sintered raw material containing iron ore and limestone, wherein the iron ore contains at least a portion of Al ₂ O ₃ of 2.0 mass% or more and an average particle size of 2 A method for producing a sintered ore comprising iron ore of 0.0 mm or less, wherein the limestone has an average particle size of 2.0 mm or more and a content of fine particles having a particle size of 0.25 mm or less is 15 mass% or less. The iron ore containing Al ₂ O ₃ in an amount of 2.0 mass% or more and an average particle size of 2.0 mm or less contains P in an amount of 0.1 mass% or more. Production method of ore.