CN-121976036-A - Flux pellet based on medium-high silicon iron concentrate and preparation method thereof

CN121976036ACN 121976036 ACN121976036 ACN 121976036ACN-121976036-A

Abstract

The invention discloses a fluxed pellet based on medium-high silicon iron concentrate and a preparation method thereof, wherein the fluxed pellet is of a three-layer composite core-shell structure, the content of SiO 2 in the iron concentrate is gradually reduced from the spherical core to the shell of the fluxed pellet, the three-layer composite fluxed pellet is prepared, the alkalinity stability of the fluxed pellet is ensured, the alkalinity and quality of the pellet are synchronously optimized, the phenomenon of excessive adhesion in the process of producing high silicon fluxed product is reduced, the internal structure of the pellet is optimized, the production and operation cost is finally reduced, and a new idea is provided for preparing alkaline pellets from low-grade high silicon iron concentrate.

Inventors

LI JINLIAN
PAN ZHONG
SUN TAO
LIU XINZHANG
XIA FENG
JIN JIN
YAN QINGSHUANG
SUN CHAOYONG
LIU SHUAI
ZOU QIANG

Assignees

鞍钢股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260209

Claims (9)

1. The fluxed pellet based on the medium-high silicon iron concentrate is characterized by being of a three-layer composite core-shell structure, and comprises the following components: The ball core comprises, by mass, 85% -90% of high-silicon iron concentrate, 8% -13% of slaked lime and 1% -3% of a binder, wherein the content of SiO 2 in the high-silicon iron concentrate is more than 7%; the middle layer is coated on the outer surface of the ball core and comprises, by mass, 88% -92% of middle ferrosilicon concentrate, 3% -7% of slaked lime, 3% -6% of limestone and 1% -3% of binder, wherein the content of SiO 2 in the middle ferrosilicon concentrate is more than or equal to 6% and less than or equal to 7%; The shell layer is coated on the outer surface of the middle layer and comprises, by mass, 89% -93% of low-silicon iron concentrate, 5% -9% of limestone and 1% -2% of binder, wherein the content of SiO 2 in the low-silicon iron concentrate is less than 6%.
2. The fluxed pellets based on the medium-high silicon iron concentrate according to claim 1, wherein the compressive strength of the fluxed pellets is 2000-5000N, the drum strength is 85-96%, the expansion rate is 8-15%, and the reduction degree is 65-90%.
3. The fluxed pellet based on medium-high silicon iron concentrate according to claim 1, wherein the diameter of the pellet core is 3-5 mm; the thickness of the middle layer is 2-5 mm; the thickness of the shell layer is 4-6 mm.
4. The fluxed pellets based on medium and high silicon iron concentrate according to claim 1, wherein the binders in the pellet core, the intermediate layer and the shell layer comprise at least one of a composite bentonite, an iron-based binder and an organic binder, respectively.
5. The fluxed pellet based on the medium-high silicon iron concentrate according to claim 1, wherein the fluxed pellet comprises 57% -65% of TFe, 0.3% -2.0% of FeO, 5.5% -8% of SiO 2 , 4% -8% of CaO and 0.2% -1.0% of MgO.
6. A method for the preparation of flux pellets based on medium and high silicon iron concentrate according to any one of claims 1-5, characterized by the steps of: s1, burdening high-silicon iron concentrate, slaked lime and a binder according to a target binary alkalinity R of a finished product pellet, and adding water for mixing to obtain a mixture A; s2, pelletizing the mixture A to obtain spherical cores; s3, burdening the medium-silicon iron concentrate, slaked lime, limestone and a binder according to the target binary alkalinity R of the finished pellets, and adding water for mixing to obtain a mixture B; S4, pelletizing by taking a spherical core as a core layer and taking the mixture B as an intermediate layer adhesion material, so as to coat an intermediate layer on the spherical core, thereby obtaining a composite structure I; s5, burdening low-silicon iron concentrate, limestone and a binder according to the target binary alkalinity R of the finished pellets, and adding water for mixing to obtain a mixture C; s6, pelletizing by taking the first composite structure as a core layer and taking the mixture C as a shell adhesion material so as to coat a shell layer on the first composite structure to obtain a second composite structure; and S7, after screening the composite structure II, sequentially drying, preheating, roasting and cooling the obtained green pellets to obtain the fluxed pellets.
7. The method for preparing the flux pellets based on the medium-high silicon iron concentrate according to claim 6, wherein the target binary basicity r=cao/SiO 2 of the finished pellets is in the range of 0.6-1.0.
8. The method for preparing the flux pellets based on the medium-high silicon iron concentrate according to claim 6, wherein in the step S1, the granularity level of the high silicon iron concentrate, the lime hydrate and the binder is controlled in the process of mixing ores, wherein the granularity composition of the high silicon iron concentrate comprises more than 80% of particles with the granularity of less than 44 mu m in terms of volume fraction, more than 90% of particles with the granularity of less than 44 mu m in terms of volume fraction, and more than 95% of particles with the granularity of less than 44 mu m in terms of volume fraction; In the step S3, the granularity level of the ferrosilicon concentrate, the slaked lime, the limestone and the binder is controlled in the ore mixing process, wherein the granularity of the ferrosilicon concentrate is more than 80 percent in terms of volume fraction, the granularity of the slaked lime is more than 90 percent in terms of volume fraction, the granularity of the limestone is more than 90 percent in terms of volume fraction, and the granularity of the binder is more than 95 percent in terms of volume fraction, the granularity of the binder is less than 44 mu m; In the step S5, the granularity level of the low-silicon iron concentrate, limestone and a binder is required to be controlled in the ore mixing process, wherein the granularity composition of the low-silicon iron concentrate comprises more than 80% of particles with the granularity of less than 44 mu m in terms of volume fraction, the granularity composition of the limestone comprises more than 90% of particles with the granularity of less than 44 mu m in terms of volume fraction, and the granularity composition of the binder comprises more than 95% of particles with the granularity of less than 44 mu m in terms of volume fraction.
9. The preparation method of the flux pellets based on the medium-high silicon iron concentrate, which is disclosed in claim 6, is characterized in that in the step S7, the drying temperature is 200-500 ℃, and the drying time is 10-15 min; the preheating temperature is 900-1050 ℃, and the preheating time is 8-15 min; the roasting temperature is 1200-1250 ℃, and the roasting time is 10-20 min.

Description

Flux pellet based on medium-high silicon iron concentrate and preparation method thereof Technical Field The invention relates to the technical field of sintered pellets, in particular to a flux pellet based on medium-high silicon iron concentrate and a preparation method thereof. Background Under the guidance of a double-carbon target, the blast furnace ironmaking direction gradually develops to a low-carbon energy structure, and the change of the blast furnace burden structure becomes one of effective ways for reducing carbon emission. The method improves the charging proportion of the fluxed pellets, and reduces the consumption of the sintering ore, thereby becoming a main furnace burden structure for future blast furnace production. This will facilitate the reduction of carbon emissions from both raw material production and ironmaking applications, while the rational transfer of flux will also have a positive effect on the improvement of the metallurgical properties of the charge. Therefore, the research on the preparation and application performances of the fluxed pellets has important significance for the green and efficient production of future blast furnaces in China. Currently, iron ore resources in China generally show the characteristics of lean, fine and miscellaneous, and the iron grade of the iron ore is generally lower than 36%. The iron ore is fine ground and beneficiated, has extremely fine granularity, is difficult to meet the requirements of a sintering process, and is suitable for being used as a production raw material of acid pellets. However, the content of SiO 2 in the iron ore concentrate is generally high, generally between 5% and 7%, and part of the SiO 2 is even more than 7%, but the SiO 2 is not suitable for preparing fluxed pellets. In addition, limestone is generally added for regulating the alkalinity in the production of the fluxed pellets, and because the content of CaO in the limestone is low, the addition amount is large in the production of pellets with high alkalinity, and particularly, under the conditions of high content of SiO 2 in concentrate powder and coarse granularity, a large amount of binder is needed, so that the content of SiO 2 in the pellets is further increased, the requirements of blast furnace concentrate cannot be met, the fuel consumption is reduced, and the carbonate decomposition reaction occurs in the roasting process of the limestone, so that the heat absorption capacity is large, and the energy consumption in the production process of the pellets is increased. The patent with the application number 2019102130731 discloses a method and a device for preparing alkaline pellets by using slaked lime, wherein the method comprises the following steps of crushing the slaked lime to a particle size of below 3mm, adding water for three-stage digestion, winnowing to obtain slaked lime with the Ca (OH) 2 content of not less than 86%, the water content of less than 1.5% and the specific surface area of more than 13000cm 2/cm3, mixing the slaked lime, concentrate powder, a binder and a magnesium-containing additive uniformly to obtain an intermediate mixture, and sequentially pelletizing, screening and roasting the intermediate mixture to obtain the alkaline pellets. The patent with the application number 2016108750787 discloses a preparation method of alkaline pellets and a preparation method of the alkaline pellets and a mineral powder mixture used in the field of blast furnace metallurgy, wherein the preparation method of the alkaline pellets comprises the steps of uniformly mixing slaked lime with sodium bentonite to form a slaked lime mixture, wherein the slaked lime mixture comprises 96% -98% by mass of slaked lime and 2% -4% by mass of sodium bentonite, mixing the slaked lime mixture into concentrate powder to form a mineral powder mixture, wherein the mineral powder mixture comprises 95% -99% by mass of concentrate powder and 1% -5% by mass of slaked lime mixture, and sieving green pellets with qualified granularity after the mineral powder mixture is prepared into green pellets, so as to obtain the alkaline pellets. Patent application number 2016100272664 discloses a method for preparing alkaline pellets by utilizing steel slag and a product prepared by the method, wherein the method comprises the steps of uniformly mixing steel slag powder and iron fine powder to obtain a mixture, and sequentially performing pelletization, drying, preheating, roasting and circular cooling treatment on the mixture to obtain the alkaline pellets. In conclusion, when the content of SiO 2 in the iron concentrate is less than 4%, the method can be used for preparing normal fluxed pellets, when the content of SiO 2 in the iron concentrate is 4% -6%, the method can be used for preparing medium silicon fluxed pellets, when the content of SiO 2 in the iron concentrate is more than 6%, the method can be used for preparing high silicon fluxed pellets, and because the content of