BR-112023019813-B1 - METHOD OF PRODUCING SINTERED ORE

BR112023019813B1BR 112023019813 B1BR112023019813 B1BR 112023019813B1BR-112023019813-B1

Abstract

PRODUCTION METHOD AND DISINTEGRATION SUPPRESSION METHOD FOR SINTERED ORE. A production method and a disintegration suppression method for sintered ore are proposed that allow sintered ore having low reduction-disintegration properties to be obtained through feedstock design and temperature control, without requiring costly investment in facilities. In this sintered ore production method, the composite feedstocks for sintering are granulated to produce granulated feedstocks for sintering, and the granulated feedstocks for sintering are sintered to obtain sintered ore. As composite feedstocks for sintering, materials in which the Fe2O3 / (Fe2O3 + CaO) ratio between Fe2O3 and CaO included among the materials is within a range of 0.76 to 0.84 are used for sintering. Thus, the reduction-disintegration (RDI) property of the sintered ore can be improved.

Inventors

KENTA TAKEHARA
Takahide Higuchi
Tetsuya Yamamoto

Assignees

JFE STEEL CORPORATION

Dates

Publication Date: 20260317
Application Date: 20211124
Priority Date: 20210331

Claims (2)

1. Method of producing sintered ore comprising granulation of composite feedstocks for sintering to produce granulated feedstocks for sintering and sintering of the granulated feedstocks for sintering to obtain sintered ore (2, 12), characterized in that, as the composite feedstocks for sintering, materials of which a ratio of Fe2O3 / (Fe2O3 + CaO) between Fe2O3 and CaO included among the materials is within a range of 0.76 to 0.84 are sintered.
2. Method for producing sintered ore, according to claim 1, characterized in that the ratio of Fe2O3 / (Fe2O3 + CaO) is defined as 0.76 to 0.80.

Description

TECHNICAL FIELD [001] The present invention relates to a method of production and a method of suppressing disintegration for sintered ore having excellent reduction-disintegration characteristics that is used as feedstock for a direct reduction process or a blast furnace process. TECHNICAL BACKGROUND [002] A blast furnace used in the steel industry is a facility in which lump ore, sintered ore, etc., which are sources of iron, are charged from the top of a furnace along with coke, while a reducing gas is blown from a lower part of the furnace to melt and reduce the iron sources and thus produce molten pig iron. To promote the reaction between the reducing gas and the iron sources, it is necessary to allow a sufficient amount of gas to flow inside the blast furnace and improve the air permeability inside the furnace to increase the rate of molten pig iron production and achieve cost reduction. [003] It is widely known that reduction in a blast furnace causes a decrease in the strength of the sintered ore and makes it prone to disintegration, which is called reduction disintegration. To increase air permeability in a blast furnace, particularly the disintegration of the sintered ore constituting a raw material needs to be mitigated, and the suppression of the aforementioned reduction disintegration is sought. [004] Air permeability has recently become important in blast furnace processes in the countercurrent flow layer-type direct reduction process (MIDREX®) developed to reduce CO2. In particular, when disintegration during reduction increases, clumping occurs which is agglomeration within the furnace, and this clumping obstructs the discharge of raw materials, which is highly likely to lead to major operational problems. [005] Given the above, sintered ore that does not undergo reduction disintegration is demanded as a raw material for both the conventional direct reduction process and the blast furnace process. It is known that in the reduction disintegration of sintered ore, as the hematite in the sintered ore transforms into magnetite during reduction, volume expansion and crack formation occur, causing a decrease in resistance and further disintegration. As methods to mitigate the disintegration of sintered ore reduction, technologies to reduce secondary hematite have been proposed so far. [006] As technologies to suppress the formation of secondary hematite, Patent Literature 1 and 2 propose technologies that sinter magnetite ore by microwave irradiation, it being stated that this sintering method enables the production of sintered ore composed mainly of magnetite. Patent Literature 3 proposes a technology that reduces the amount of hematite, including secondary hematite, decreasing the hematite in the sintered ore and reducing it to wustite. LIST OF QUOTES PATENTARY LITERATURE [007] Patent Literature 1: JP2020-41222A Patent Literature 2: JP2018-510970A (Japanese Translation of the PCT International Application Publication) Patent Literature 3: JP2003-293045A SUMMARY OF THE INVENTION TECHNICAL PROBLEM [008] However, the methods disclosed in Patent Literature 1 and 2 have a problem, as they are only applicable to magnetite-based ore (Fe3O4), which, as a source of iron, is available in smaller quantities on the market, so installation and operating costs tend to be high. The method disclosed in Patent Literature 3 requires the use of a reducing gas to reduce the iron source and therefore has the problem that the sintering machine needs to be equipped with a reducing device, which increases the operational cost of the reduction. [009] One objective of the present invention is to provide a production method and a disintegration suppression method for sintered ore that allows sintered ore having low reduction-disintegration properties to be obtained through raw material design and temperature control, without requiring costly investment in facilities. SOLUTION TO THE PROBLEM [010] In conducting research to solve the problems described above with conventional technologies and achieve the objective, the present inventors first focused on a state diagram of Fe2O3 and CaO (see FIG. 1). In the process, it was learned that there is a region where mainly calcium ferrite crystallizes, adjusting a ratio of Fe2O3 / (Fe2O3 + CaO) when a solid phase is crystallized from the melt. Sintering in this region had not been carried out until then because, in a common idea, after exiting a sintering machine, the sintered ore is usually cooled by a cooling machine and returns to room temperature, and therefore hematite tends to crystallize at the end. [011] Focus was placed on the fact that a sintering machine is for a rapid cooling process and a method was developed that reduces the formation of secondary hematite by cooling the sintered ore before the calcium ferrite to be crystallized transforms into hematite. Specifically, various temperatures and components were considered and it was found that adjusting the components of