Method for improving reduction degradation performance of sintered ore

Abstract

The invention discloses a method for improving the reduction degradation performance of sintered ore, and relates to the technical field of ferrous metallurgy, and the method comprises the following steps: mixing an iron-containing raw material, a flux, return mine and fuel, and granulating to obtain a mixture; dividing the mixture into a plurality of parts; mixing each part of the mixture with limonite to form a sintered raw material; the sintered raw materials are sequentially distributed and stacked and sintered to form sintered ore, and the adding proportion of the limonite in the multiple layers of sintered raw materials is sequentially decreased from bottom to top. By optimizing the adding proportion of the limonite in the mixture and adopting the limonite separate adding technology, generation of a calcium ferrite liquid phase is promoted, the quality of sintered ore is effectively improved, and therefore the low-temperature reduction degradation rate of the sintered ore is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of iron and steel metallurgy, and particularly to a method for improving the reduction and powdering properties of sinter. Background Art

[0002] Iron ore sintering is an important link in the production of the iron and steel industry, and its product sinter is the main raw material for blast furnace ironmaking. With the gradual depletion of high-quality iron ore resources, limonite, as a low-grade iron ore resource, has an increasing proportion of use. However, due to its high water content, low crystallization water decomposition temperature and other characteristics, limonite is prone to form a loose structure during the sintering process, resulting in a complex mineral phase composition of the sinter, reduced strength, and further affecting the reduction and powdering properties of the sinter. Due to the particularity of limonite, the sintering process has fine requirements for the proportion of limonite and the conditions of segregation distribution.

[0003] CN202410007331.1 discloses a method for improving the low-temperature reduction and powdering index of iron ore sinter, which improves the low-temperature reduction and powdering index of iron ore sinter by controlling the sinter composition, the activity of quicklime and the thickness of the sintering bed. However, this method has high requirements for the stability of the sinter composition and complex control means. CN202310284847.6 discloses a method for suppressing the low-temperature reduction and powdering of high-bed sinter. By blowing an inhibitory gas onto the top layer of the sintering material surface when the high-bed sintering is about to end, it can inhibit the oxidation of magnetite in the lower high-temperature sinter into secondary hematite, thereby improving the low-temperature reduction and powdering properties of the lower sinter, so that the low-temperature reduction and powdering rate RDI-(+3.15) of the finished sinter is ≥75%. However, this method requires precise control of the time when the sintering is about to end and maintaining the stability of the inhibitory gas.

[0004] The prior art does not address the particularity of a high limonite ratio. Therefore, there is an urgent need to develop a method for improving the low-temperature reduction and powdering properties of sinter with a high limonite ratio. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for improving the reduction and powdering properties of sinter.

[0006] To solve the above technical problems, the technical solution of the present invention is as follows: A method for improving the reduction and powdering properties of sinter, comprising: Mixing iron-containing raw materials, fluxes, return fines and fuels and granulating to obtain a mixed material; Dividing the mixed material into several portions; Mixing each portion of the mixed material with limonite to form green sinter; Stack the sintering raw materials in layers in sequence and sinter them to form sintered ore. The addition ratio of limonite in several layers of the sintering raw materials decreases successively from bottom to top.

[0007] As a preferred embodiment of the method for improving the reduction degradation performance of sintered ore according to the present invention, wherein: the flux includes one or more of dolomite powder, limestone, and quicklime.

[0008] As a preferred embodiment of the method for improving the reduction degradation performance of sintered ore according to the present invention, wherein: the mixture is divided into three portions.

[0009] As a preferred embodiment of the method for improving the reduction degradation performance of sintered ore according to the present invention, wherein: among the three layers of the sintering raw materials, the addition ratio of limonite in the upper sintering raw material is 0-20%, the addition ratio of limonite in the middle sintering raw material is 20-40%, and the addition ratio of limonite in the lower sintering raw material is 40-60%.

[0010] As a preferred embodiment of the method for improving the reduction degradation performance of sintered ore according to the present invention, wherein: the addition ratio of limonite is 50%-80% of the total raw material mass.

[0011] As a preferred embodiment of the method for improving the reduction degradation performance of sintered ore according to the present invention, wherein: the particle size of the limonite is 3 mm.

[0012] The beneficial effects of the present invention are: The present invention separately screens out the coarse-grained limonite, and then granulates the remaining iron-containing raw materials, dolomite powder, limestone, quicklime, return ore, and fuel to obtain a sintering mixture. The mixture is divided into three portions, and then mixed with different proportions of coarse-grained limonite, and then fed in layers and ignited for sintering. By optimizing the addition ratio of limonite in the mixture and adopting the technology of adding limonite in separate portions, it promotes the formation of calcium ferrite liquid phase, effectively improves the quality of sintered ore, and thus improves the low-temperature reduction degradation rate of sintered ore. Specific Embodiments

[0013] To make the content of the present invention easier to be clearly understood, the following further detailed description of the present invention is made according to specific embodiments.

[0014] Adopting a high proportion of limonite is one of the important ways for the sintering process to reduce raw material costs and improve the comprehensive utilization rate of resources. However, due to the characteristics of limonite such as high water content and low crystal water decomposition temperature, it is easy to form a loose structure during the sintering process, resulting in a complex mineral phase composition of sintered ore, reduced strength, and further affecting the reduction degradation performance of sintered ore.

[0015] To this end, the embodiments of the present application provide a method for improving the reduction degradation performance of sinter. The method specifically includes the following steps: Step S101: Granulate the iron-containing raw materials, fluxes, return fines, and fuels after mixing to obtain a mixed material; Specifically, the coarse-grained limonite in the raw materials is separately screened out, and the remaining iron-containing raw materials, fluxes, return fines, and fuels are mixed and granulated.

[0016] Among them, the above fluxes include one or more of dolomite powder, limestone, and quicklime. The above iron-containing raw materials are iron-containing raw materials used in the sintering process.

[0017] Step S102: Divide the mixed material into several portions.

[0018] In this embodiment, the mixed material is divided into three portions.

[0019] Step S103: Mix each portion of the mixed material with limonite to form green sinter; Specifically, the three portions of the mixed material are mixed with coarse-grained limonite in different proportions to form green sinter. Among them, in these three portions of green sinter, the addition ratios of coarse-grained limonite are 0-20%, 20-40%, and 40-60% respectively.

[0020] Step S104: Layer the green sinter in sequence and sinter to form sinter. The addition ratio of limonite in several layers of sintering material layers decreases sequentially from bottom to top.

[0021] Specifically, the three portions of green sinter are layered in sequence along the vertical direction, and the addition ratio of limonite in the upper green sinter is 0-20%, the addition ratio of limonite in the middle green sinter is 20-40%, and the addition ratio of limonite in the lower green sinter is 40-60%.

[0022] After the three portions of green sinter are layered, sinter the sintering material, and finally obtain sinter.

[0023] It should be noted that the addition ratio of coarse-grained limonite is 50%-80% of the total mass of the raw materials. Among them, the particle size of the coarse-grained limonite is 3 mm.

[0024] The technical solution of the present application separately screens out the coarse-grained limonite, granulates the remaining iron-containing raw materials, dolomite powder, limestone, quicklime, return fines, and fuels to obtain sintering mixture, divides the mixture into three portions, then mixes with coarse-grained limonite in different proportions, and then layers and ignites for sintering in sequence. By optimizing the addition ratio of limonite in the mixture and adopting the technology of adding limonite separately, it promotes the formation of calcium ferrite liquid phase, effectively improves the quality of sintered ore, and thus improves the low-temperature reduction degradation rate of sinter.

[0025] In addition to the above embodiments, the present invention may have other implementation manners; all technical solutions formed by using equivalent replacements or equivalent transformations fall within the protection scope claimed by the present invention.

Claims

1. A method for improving the reduction degradation performance of sinter, characterized in that: Including: Granulating after mixing iron-containing raw materials, fluxes, return fines and fuels to obtain a mixed material; Dividing the mixed material into several portions; Mixing each portion of the mixed material with limonite to form a green sintering material; Stacking and sintering the green sintering materials in layers in sequence to form sinter, and the addition ratio of limonite in several layers of the green sintering materials decreases successively from bottom to top.

2. The method for improving the reduction degradation performance of sintered ore according to claim 1, characterized in that: The flux includes one or more of dolomite powder, limestone, and quicklime.

3. The method for improving the reduction degradation performance of sinter according to claim 1, characterized in that: The mixed material is divided into three portions.

4. The method for improving the reduction degradation property of sinter according to claim 1, characterized in that: Among the three layers of the green sintering materials, the addition ratio of limonite in the upper green sintering material is 0-20%, the addition ratio of limonite in the middle green sintering material is 20-40%, and the addition ratio of limonite in the lower green sintering material is 40-60%.

5. The method for improving the reduction degradation performance of sinter according to claim 1, characterized in that: The addition ratio of the limonite is 50%-80% of the total raw material mass.

6. The method for improving the reduction degradation performance of sintered ore according to claim 1, characterized in that: The particle size of the limonite is 3 mm.