CN109423555B - Efficient iron ore sintering method using low-silicon iron fine powder - Google Patents
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
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- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
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Abstract
The invention provides an iron ore and stone height using low-silicon iron fine powderThe efficient sintering method is characterized in that the low-silicon iron fine powder is granulated and pelletized into a special structure which takes return ores with large granularity as a core, iron fine powder, fine grain fusing agents and fine grain coke powder as an inner adhesion layer and fine grain return ores as an outer adhesion layer, so that the technical problems that the iron fine powder is poor in granulation property and difficult to granulate and the high-temperature sintering property is poor and difficult to mineralize are solved, and meanwhile, part of coarse-grained coke powder and coarse-grained limestone fusing agents are added. The invention optimizes the indexes of sintered mineral products and quality, and improves the utilization coefficient of the sintering machine by 1.6-4.7t/m compared with the conventional sintering process under the condition of the same raw material structure2D, the sintering yield is improved by 0.8-1.5%, and the drum strength of the sintering ore is improved by 1.6-2.4%.
Description
Technical Field
The invention relates to the technical field of ferrous metallurgy sintering processes, in particular to an efficient iron ore sintering method using low-silicon iron fine powder.
Background
The sintered ore is the most important iron-containing charge of the blast furnace, and the proportion of the sintered ore in the charge structure of the blast furnace is usually about 75-78%. The gangue content in sintered powder ore is continuously increased due to the deterioration of fine ore resources of iron ore in recent years, such as southeast Brazil powder ore, SiO in ore2The content is promoted to about 6-7% from about 4% year by year, even SiO appears in the iron ore market2Up to 10-12% of ultra-high silica powder ore product. Combining with the conventional sintering process flow shown in figure 1, the conventional sintering ore is prepared by mixing uniformly mixed ore, return fine, flux (quicklime, limestone and dolomite) and coke powder, and then carrying out primary mixing, secondary mixing, material distribution, ignition, sintering, cooling and granule finishing on the mixture to obtain the finished product sintering ore. In order to ensure the requirements of low-slag smelting and high coal injection ratio of the blast furnace, the charging grade of the blast furnace cannot be reduced, and in order to reconcile the contradiction between the deterioration of iron ore resources and the charging grade of the blast furnace, technical countermeasures adopted in production are as follows: firstly, the proportion of high-grade pellets in a blast furnace burden structure is improved; or ② improving the high-grade and low-SiO in the sintering ore blending structure2And (3) fine powder proportion. Although the above technical measures can alleviate the contradiction between the exhaustion of high-quality iron ore resources and the blast-furnace-entering grade to some extent, the technical measures are also technically influenced by factors such as the characteristics of the raw materials and the operating conditionsTo the next step. The restriction of the multi-purpose pellet ore for blast furnace ore blending lies in: generally speaking, the high temperature performance of the pellet is inferior to that of the high alkalinity sinter, and the melting initial temperature TsAnd the dropping temperature TdLow, causing the softening and melting of the blast furnace to have upward moving tendency; the pellets are easy to produce fine powder by low-temperature reduction and pulverization, and have negative influence on the air permeability of the blast furnace; the pellets roll more easily in the material distribution process, and the adjustment effect on the upper part of the blast furnace is influenced, so the operation difficulty of the multi-purpose pellet blast furnace is increased. The restriction of the multipurpose iron fine powder for sintering and ore blending lies in: fine granularity of iron concentrate, reduced air permeability of a sinter bed, increased sintering negative pressure and increased transverse instability of the sinter bed; on the other hand, the assimilation temperature of the iron fine powder is usually high, and the assimilation temperature refers to the lowest reaction temperature of the fine powder and the CaO flux, so that the fine powder is not easy to sinter into ores, the sintering operation difficulty is increased due to the fact that the multipurpose iron fine powder is sintered, and the yield of the sintered ores is reduced.
Chinese patent application No. CN200610031431.X, an iron material pretreatment reinforced sintering method, aiming at the characteristic of poor granulation of iron fine powder, discloses a pretreatment method of a high-pressure roller mill or a wet mill, which improves the expression activity and surface hydrophilicity of specularite fine powder and improves the granulation performance, thereby improving the air permeability of a sinter layer and achieving the purpose of improving the sintering yield. Chinese patent application CN201310255070.7, a method for pre-pressing, molding and reinforced sintering of fine iron ore concentrate, also aiming at the characteristic of difficult granulation of fine iron ore, discloses a method for pre-pressing fine iron ore concentrate into cylindrical granules by a high-pressure roller molding machine, and then mixing the granules with other raw materials for granulation. The above patent application mainly aims at the characteristic that fine iron powder is difficult to pelletize, and adopts a pretreatment mode, such as a high-pressure roller grinding mode, a lubricating grinding mode, or a high-pressure roller forming mode, to improve the pelletization performance, thereby improving the air permeability of a sinter layer and achieving the purpose of optimizing the sintering yield and quality.
Chinese patent application CN01114546.3, a method for preparing high-iron low-silicon sinter, discloses a sintering process comprising mixing low-silicon iron fine powder, fine-grained iron-containing miscellaneous materials and fine-grained flux (limestone or quicklime) to prepare adhesive particles with basicity of 1.8-6.0, mixing with large-grained iron ore powder and return-ore nucleation particles, and granulating (or mixing low-silicon iron fine powder, fine-grained iron-containing miscellaneous materials and fine-grained flux, granulating by disc pelletizing and/or cylinder pelletizing, mixing with large-grained iron ore powder and return-ore nucleation particles, and granulating). Chinese patent application CN201310417934.0, a method for strengthening the sintering of high proportion iron ore concentrate, discloses a sintering process in which iron ore concentrate, quicklime and coke powder are added into a cylindrical granulator or a disc granulator first to perform first stage granulation, and then the prepared pellets are added into the cylindrical granulator together with other raw materials to perform granulation. The above patent applications are characterized in that firstly, iron fine powder difficult to pelletize is mixed (or further pelletized) with quicklime flux, the pelletization performance of the iron fine powder is enhanced by calcium hydroxide colloid generated after slaking the quicklime, and then the mixture is directly mixed and pelletized with other raw materials; or the iron fine powder is independently granulated into small balls, and then is mixed with other raw materials and granulated, so that the aim of enhancing the sintering yield and quality is fulfilled.
Disclosure of Invention
Technical problem to be solved
The invention provides an efficient iron ore sintering method using low-silicon iron concentrate powder, which solves the problems of deterioration of the sintering process, sintering mineral products and quality reduction under the condition of using the iron concentrate powder in a high proportion, and provides an effective technical means for optimizing the blast furnace burden structure and reducing the molten iron cost.
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme:
an efficient iron ore sintering method using low-silicon iron fine powder comprises the following steps:
s1, selecting an iron-containing raw material, return ores, dolomite powder, coke powder, limestone powder and quick lime as a sintering mixture, wherein the iron-containing raw material is fine iron powder and a mixed ore, the fine iron powder accounts for not more than 25% of the mass portion of the sintering mixture, and the fine iron powder accounts for not more than 40% of the mixed ore; the mass portion of the return ores in the sintering mixture is 25-30%; the dolomite powder accounts for 3-5% of the mass proportion of the sintering mixture; the coke powder accounts for 2-5% of the mass proportion of the sintering mixture; the limestone powder accounts for 2-4% of the mass proportion of the sintering mixture; the quicklime accounts for 3-5% of the mass of the sintering mixture;
s2, the return fines comprise sinter powders, the sinter powders are the undersize parts of finished sinter powders after being screened before the blast furnace is fed, the granularity is less than 5mm, the return fines are divided into A, B parts, the part A is screened into two parts of more than 1mm size fraction and less than 1mm size fraction through a screening system, and the part B, coke powder, limestone powder, quicklime and dolomite powder enter a cylindrical mixing granulator together with the uniform mixing ores;
s3, dividing the coke powder into A, B parts, sieving the part A into two parts of a size fraction smaller than 0.5mm and a size fraction larger than 0.5mm through a sieving system, and feeding the part B, return ores, limestone powder, quicklime and dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s4, dividing the limestone powder into A, B parts, sieving the part A into two parts of a size fraction smaller than 0.5mm and a size fraction larger than 0.5mm through a sieving system, and feeding the part B, return ores, coke powder, quicklime, dolomite powder and uniformly mixed ores into a cylindrical mixing granulator;
s5, dividing the quicklime into A, B parts, taking out the part A, and feeding the part B, the return ores, the coke powder, the limestone powder and the dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s6, feeding all dolomite powder, return ores, coke powder, limestone powder and dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s7, screening the fine iron powder and part A of coke powder to obtain a part with a particle size smaller than 0.5mm, screening part A of limestone powder to obtain a part with a particle size smaller than 0.5mm, and adding part A of quicklime into a powerful mixer, adding water to moisten materials in the process of uniformly mixing, wherein the water content of the materials discharged by the powerful mixer is 2-4%, and the mixing time is 1-3 min;
s8, sieving the return ores of the part A, adding water to prewet the part with the size larger than 1mm, and controlling the water addition amount to be 3-5% of the material moisture;
s9, adding the materials discharged from the intensive mixer and the prewetted return ores with the size fraction larger than 1mm into a cylindrical granulator from a feeding end, sieving part A of the return ores with the size fraction smaller than 1mm, adding the sieved part A of the return ores into the cylindrical granulator from a discharging end, wherein the adding position is 1/3 of the distance from a material falling point to the discharging end, which accounts for the length of the whole cylindrical granulator;
s10, adding the B part of sintering powder, the B part of coke powder, the B part of limestone powder, the B part of quicklime and dolomite powder and the mixed ore into a cylindrical mixing granulator from a feed end, adding the material discharged from the cylindrical granulator, the part A of coke powder which is sieved and is larger than 0.5mm in size fraction, and the part A of limestone powder which is sieved and is larger than 0.5mm in size fraction from a discharge end of the cylindrical mixing granulator, wherein the adding position is 1/3 of the distance from a material falling point to the discharge end, which accounts for the length of the whole cylindrical mixing granulator;
and S11, sequentially feeding the materials discharged from the cylindrical mixing granulator into the processes of material distribution, ignition, sintering, cooling and granule finishing to obtain finished sintered ore for use by a blast furnace.
Further, the iron concentrate powder in the step S1 is low-silicon iron concentrate powder, and SiO in the low-silicon iron concentrate powder2The mass percentage content is less than 3 percent.
Further, the blended ore in the step S1 contains iron ore powder, pellets and lump ore undersize powder, and iron-containing miscellaneous materials, but does not include fine iron powder.
Further, the proportions of the return ores A part and B part in the sinter mix in the step S2 are respectively marked as PARFAnd PBRF，PARFIs calculated by the formula
PBRFThe PA is subtracted from the proportion of the whole return ores in the sintering mixtureRFIn the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%; n is a proportional coefficient, and the value range is 0.7-1.3; a (%) is the proportion of more than 1mm size fraction in the return fines; in the formula, the proportionality coefficient n is determined by the value of m, and the function relationship between the proportionality coefficient n and the proportionality coefficient is as follows: n (m) ═ 0.024m + 1.35.
Further, the proportions of the part A and the part B of the coke powder in the sintering mixture in the step S3 are respectively marked as PACAnd PBC，PACThe calculation formula of (2) is as follows: PAC＝0.08m+0.6；PBCThe PA is subtracted from the proportion of the whole coke powder in the sintering mixtureC(ii) a In the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%.
Further, the proportions of the limestone powder A part and the limestone powder B part in the sintering mixture in the step S4 are respectively marked as PASAnd PBS，PASThe calculation formula of (2) is as follows: PAS＝0.05m+0.8；PBSThe PA is subtracted from the proportion of the total limestone powder in the sintering mixtureS(ii) a In the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%.
Further, the proportions of the part A and the part B of the quicklime in the sinter mix in the step S5 are respectively marked as PALAnd PBL，PALThe calculation formula of (2) is as follows: PAL＝0.125m+0.15；PBLThe PA is subtracted from the proportion of the whole quicklime in the sintering mixtureL(ii) a In the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%.
Further, in step S9, water is supplemented to the cylindrical granulator during the operation, the water content of the discharged material of the cylindrical granulator is 4-6%, and the granulation time is 3-8 min.
Further, in step S10, water is added into the cylindrical mixer-granulator during the operation, the water content of the material discharged from the cylindrical mixer-granulator is 6-8%, and the mixing granulation time is 6-10 min.
(III) advantageous effects
The invention has the beneficial effects that: an iron ore high-efficiency sintering method using low-silicon iron fine powder is characterized in that iron fine powder is granulated and pelletized into a special structure with large-granularity return ores as a core, iron fine powder, fine-grain flux and fine-grain coke powder as inner adhesive layers and fine-grain return ores as outer adhesive layers, so that the technical problems that the iron fine powder is poor in granulation property and difficult to granulate and high-temperature sintering property is poor and mineralize are solved; meanwhile, partial coarse-grained coke powder and coarse-grained limestone flux are added, and the sintered mineral product and quality index are optimized by the technical means, under the condition that the raw materials have the same structure,compared with the conventional sintering process, the utilization coefficient of the sintering machine is improved by 1.6-4.7t/m2D, the sintering yield is improved by 0.8-1.5%, and the drum strength of the sintering ore is improved by 1.6-2.4%.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of a conventional sintering process;
FIG. 2 is a flow chart of the method of the present invention;
FIG. 3 is a schematic view of a granulated pellet of fine iron powder;
FIG. 4 is a microscopic view of a pelletized pellet with return fines as core particles;
FIG. 5 is a graph comparing the results of productivity tests of the present invention and conventional sintering;
FIG. 6 is a graph comparing the results of yield tests of the present invention and conventional sintering;
FIG. 7 is a graph comparing the results of the drum strength test of the present invention and conventional sintering.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
With reference to fig. 2, a method for efficiently sintering iron ore by using low-silicon iron concentrate powder comprises the following steps:
s1, selecting iron-containing raw materials, return ores, dolomite powder, coke powder,Limestone powder and quicklime are used as a sintering mixture, the iron-containing raw material is iron concentrate powder and uniformly mixed ore, the mass proportion of the iron concentrate powder in the sintering mixture is not higher than 25%, and the mass proportion of the iron concentrate powder in the uniformly mixed ore is not higher than 40%; the mass portion of the return ores in the sintering mixture is 25-30%; the dolomite powder accounts for 3 to 5 percent of the mass proportion of the sintering mixture; the coke powder accounts for 2 to 5 percent of the mass portion of the sintering mixture; limestone powder accounts for 2-4% of the mass proportion of the sintering mixture; the quicklime accounts for 3-5% of the mass of the sintering mixture; the iron concentrate powder is low-silicon iron concentrate powder, and SiO in the low-silicon iron concentrate powder2The mass percentage content is lower than 3 percent; the mixed ore contains iron ore powder, pellets and lump ore undersize powder and iron-containing sundries, but does not contain iron concentrate powder;
s2, the return fines comprise sinter powders, the sinter powders are the undersize parts of finished sinter powders after being screened before the blast furnace enters the furnace, the undersize parts are also called as external return fines, the granularity is less than 5mm, the return fines are divided into A, B parts, the part A is screened into two parts with the size fraction larger than 1mm and the size fraction smaller than 1mm through a screening system, and the part B, coke powder, limestone powder, quicklime and dolomite powder and the mixed ores enter a cylindrical mixing granulator;
the proportions of the return mine part A and the part B in the sintering mixture are respectively marked as PARFAnd PBRF，PARFIs calculated by the formula
PBRFThe PA is subtracted from the proportion of the whole return ores in the sintering mixtureRFIn the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%; n is a proportional coefficient, and the value range is 0.7-1.3; a (%) is the proportion of more than 1mm size fraction in the return fines, typically around 70%; in the formula, the proportionality coefficient n is determined by the value of m, and the function relationship between the proportionality coefficient n and the proportionality coefficient is as follows: n (m) ═ -0.024m + 1.35;
s3, dividing the coke powder into A, B parts, sieving the part A into two parts of a size fraction smaller than 0.5mm and a size fraction larger than 0.5mm through a sieving system, and feeding the part B, return ores, limestone powder, quicklime and dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
part A and part B of coke powderThe proportions of the respective portions of the sinter mix are denoted as PACAnd PBC，PACThe calculation formula of (2) is as follows: PAC＝0.08m+0.6；PBCThe PA is subtracted from the proportion of the whole coke powder in the sintering mixtureC(ii) a In the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%;
s4, dividing the limestone powder into A, B parts, sieving the part A into two parts of a size fraction smaller than 0.5mm and a size fraction larger than 0.5mm through a sieving system, and feeding the part B, return ores, coke powder, quicklime, dolomite powder and uniformly mixed ores into a cylindrical mixing granulator;
the proportions of part A and part B of limestone powder in the sintering mixture are respectively marked as PASAnd PBS，PASThe calculation formula of (2) is as follows: PAS＝0.05m+0.8；PBSThe PA is subtracted from the proportion of the total limestone powder in the sintering mixtureS(ii) a In the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%;
s5, dividing the quicklime into A, B parts, taking out the part A, and feeding the part B, the return ores, the coke powder, the limestone powder and the dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
the proportion of the part A and the part B of the quicklime in the sintering mixture is respectively marked as PALAnd PBL，PALThe calculation formula of (2) is as follows: PAL＝0.125m+0.15；PBLThe PA is subtracted from the proportion of the whole quicklime in the sintering mixtureL(ii) a In the formula: m (%) is the proportion of the fine iron powder in the sintering mixture, and the value range is not higher than 25%;
s6, feeding all dolomite powder, return ores, coke powder, limestone powder and dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s7, screening the fine iron powder and part A of coke powder to obtain a part with a particle size smaller than 0.5mm, screening part A of limestone powder to obtain a part with a particle size smaller than 0.5mm, and adding part A of quicklime into a powerful mixer, adding water to moisten materials in the process of uniformly mixing, wherein the water content of the materials discharged by the powerful mixer is 2-4%, and the mixing time is 1-3 min;
s8, sieving the return ores of the part A, adding water to prewet the part with the size larger than 1mm, and controlling the water addition amount to be 3-5% of the material moisture;
s9, adding the materials discharged from the intensive mixer and the prewetted return ores with the size fraction larger than 1mm into a cylindrical granulator from a feeding end, sieving part A of the return ores with the size fraction smaller than 1mm, adding the sieved part A of the return ores into the cylindrical granulator from a discharging end, wherein the adding position is 1/3 of the distance from a material falling point to the discharging end, which accounts for the length of the whole cylindrical granulator; supplementing water to the cylindrical granulator in the operation process, wherein the discharged material water content of the cylindrical granulator is 4-6%, and the granulation time is 3-8 min;
s10, adding the B part of sintering powder, the B part of coke powder, the B part of limestone powder, the B part of quicklime and dolomite powder and the mixed ore into a cylindrical mixing granulator from a feed end, adding the material discharged from the cylindrical granulator, the part A of coke powder which is sieved and is larger than 0.5mm in size fraction, and the part A of limestone powder which is sieved and is larger than 0.5mm in size fraction from a discharge end of the cylindrical mixing granulator, wherein the adding position is 1/3 of the distance from a material falling point to the discharge end, which accounts for the length of the whole cylindrical mixing granulator; adding water into the cylindrical mixing granulator in the operation process, wherein the water content of the discharged material from the cylindrical mixing granulator is 6-8%, and the mixing granulation time is 6-10 min;
and S11, sequentially feeding the materials discharged from the cylindrical mixing granulator into the processes of material distribution, ignition, sintering, cooling and granule finishing to obtain finished sintered ore for use by a blast furnace.
The use difficulty of the iron concentrate is mainly reflected in two aspects: on the one hand, poor pelletizability makes pelletization difficult; on the other hand, the high-temperature sintering property is poor and the mineralization is difficult.
Aiming at the technical difficulty of poor pelletization performance of the fine iron powder, the fine iron powder and the quicklime are mixed in a powerful mixer, water is added for wetting in the mixing process, the quicklime is uniformly distributed in the fine iron powder, and the quicklime starts to digest to generate Ca (OH)2The colloid plays a role in strengthening the granulation of the iron concentrate. In addition, the return ores with the size fraction larger than 1mm are used as granulation core particles of the fine iron powder, and the method is also an important measure for enhancing the granulation effect of the fine iron powder. The surface of the return fine particles is irregular and porous, fine powder is easy to adhere to the particles, and the particles are notThe microstructure of the pellet which is usually suitable for being used as a granulation core particle and takes return ores as the core particle is shown in figure 4, and the return ores with the size fraction larger than 1mm are prewetted before being mixed with fine iron powder for granulation, so that the capability of the return ores as the granulation core particle for adhering the fine iron powder is further enhanced.
Aiming at the problem that fine iron powder is difficult to mineralize due to poor high-temperature sintering performance, the fine iron powder, limestone powder with the size fraction smaller than 0.5mm and quicklime are used as adhesive particles (the adhesive particles also comprise coke powder with the size fraction smaller than 0.5 mm), so that the CaO content in the adhesive particles is higher, and the high-temperature sintering performance of the fine iron powder is enhanced. Specifically, CaO and Fe in the adhered particles2O3The ratio of (A) meets the formula:
that is, CaO accounts for CaO and Fe2O3The proportion of the sum is between 11 and 18 percent; w is aCaO(%) is the CaO content in the adhered particles; w is aFe2O3(%) is Fe in the adhered particles2O3Content (c); secondly, return fines with the size fraction larger than 1mm are used as core particles for granulating the fine iron powder, so that the mineralization process of the fine iron powder is facilitated, and the reason is that the mineral composition of the return fines mainly comprises calcium ferrite, hematite, magnetite and glass, wherein the calcium ferrite is decomposed into a liquid phase and the hematite at 1250-; and adhering the return fine powder with the size fraction smaller than 1mm to the outer layer of the fine iron powder granulated pellet, so that the fine iron powder granulated pellet has the structural characteristics that the return fine powder with the size fraction larger than 1mm is taken as a core, the fine iron powder, the limestone powder with the size fraction smaller than 0.5mm, the coke powder with the size fraction smaller than 0.5mm and the quicklime are taken as inner adhesive layers, and the return fine powder with the size fraction smaller than 0.5mm is taken as an outer adhesive layer, and the structural schematic diagram is shown in fig. 3. During the feeding and mixing process of the granulated pellet of iron concentrate powder discharged from the cylindrical granulator, the inner adhesion layer comprising iron concentrate powder, flux and fuel is effectively protected under the impact of external force due to the existence of the outer adhesion layer of the granulated pellet, so as to ensure the inner adhesion layer comprising the iron concentrate powder and CaO fluxThe integrity of the flux ensures the strengthening effect of the CaO flux on the mineralization process of the fine iron powder. Because the return fine powder has good granulation performance, the return fine powder falling off from the fine iron powder granulation balls can be easily adhered to other granulation balls, and the negative influence on the gas permeation of a material layer can not be brought; finally, the coke powder with the grain size less than 0.5mm in the inner adhesion layer is in close contact with the fine iron powder and the CaO flux on the one hand, and has fine grain size and high combustion rate on the other hand, and the heat generated in the sintering process is more effectively utilized by the fine iron powder and the flux, thereby playing a role in strengthening the mineralization of the fine iron powder. In addition, the part with the particle size larger than 0.5mm after the coke powder is screened and the part with the particle size larger than 0.5mm after the limestone is screened are added from the discharge end of the cylinder mixing granulator, so that the coke powder and the limestone powder are distributed outside the granulating pellets, and the forming of a sufficient liquid phase outside the granulating pellets is facilitated, thereby effectively improving the strength of the sintered ore.
The advantages of the sintering method provided by the patent application compared with the conventional sintering process are specifically explained when the use amounts of the fine iron powder accounting for 5%, 10%, 15% and 20% of the sintering mixture are respectively used. In the specific implementation process, as the proportion of the iron concentrate is increased, the SiO in the sintering ore is kept by adjusting the ore blending structure (high-grade low-silicon concentrate replaces high-silicon powder ore) and the flux amount (limestone powder and dolomite powder) of the blending ore2The content, MgO content and basicity are kept constant, while Al2O3The content is reduced, and the content of the total iron T.Fe is increased. The ingredients of the low-silicon iron fine powder and the high-silicon fine ore used are shown in table 1.
TABLE 1 Low-silicon iron concentrate and high silica fume ore composition (mass%)
The first embodiment is as follows: the content of the fine iron powder is 5 percent of the sintered mixture
When the amount of the fine iron powder accounts for 5 percent of the proportion of the sintering mixture, the materials are distributed and processed according to the technical scheme. Calculating the proportion PA of the return mine A partRF8.8 percent, part A of the coke powder is PAC1% of limestone A in a proportion PAS1.1 percent of quicklime A and part proportion PA of quicklime AL0.8% of CaO and Fe in the adhered particles2O3The total amount was 15.7%.
The mixing time of the raw materials in the intensive mixer is 1min, the granulating time of the cylindrical granulator is 4min, the mixing and granulating time of the cylindrical mixer granulator is 8.5min, the components of the obtained sintered ore are shown in table 2, and the sintering index is shown in table 3. Meanwhile, the test results obtained by the conventional sintering method under the test conditions using the same raw materials and ratios are also shown in table 3. As can be seen from the test results, the technical process of the present invention has certain advantages compared with the conventional process.
TABLE 2 sinter composition with 5% iron concentrate powder
TABLE 3 sintering index of 5% iron concentrate powder
Example two: the content of the fine iron powder is 10 percent of the proportion of the sintered mixture
When the amount of the fine iron powder accounts for 10 percent of the proportion of the sintering mixture, the materials are distributed and processed according to the technical scheme. Calculating the proportion PA of the return mine A partRF15.9 percent, part A of the coke powder is PAC1.4%, limestone A part ratio PAS1.3 percent of quicklime A, and part proportion PA of quicklime AL1.4%, CaO in the adhered particles accounts for CaO and Fe2O3The total amount was 13.2%.
The mixing time of the raw materials in the intensive mixer was 1.3min, the granulating time of the cylindrical granulator was 5min, the mixing and granulating time of the cylindrical mixer granulator was 8min, the obtained sintered ore components were as shown in table 4, and the sintering index was as shown in table 5. Also, the test results obtained by the conventional sintering method under the test conditions using exactly the same raw materials and ratios are shown in Table 5. As can be seen from the test results, the technical process of the present invention has great advantages compared with the conventional process.
TABLE 4 sinter composition with 10% iron concentrate powder
TABLE 5 sintering index for fine iron powder dosage of 10%
Example three: the content of the fine iron powder is 15 percent of the sintered mixture
When the amount of the fine iron powder accounts for 15 percent of the proportion of the sintering mixture, the materials are distributed and processed according to the technical scheme. Calculating the proportion PA of the return mine A partRF21.2 percent, part A of the coke powder is PAC1.8%, limestone A part ratio PAS1.6 percent of quicklime A and part proportion PA of quicklime AL2.0%, CaO in the adhered particles accounted for 12.3% of the total amount of CaO and Fe2O 3.
The mixing time of the raw materials in the intensive mixer was 1.6min, the granulating time in the cylinder granulator was 6min, and the mixing and granulating time in the cylinder mixer granulator was 7.5min, and the obtained sintered ore had the compositions shown in table 6 and the sintering indexes shown in table 7. Also, the test results obtained by the conventional sintering method under the test conditions using exactly the same raw materials and ratios are shown in Table 7. As can be seen from the test results, the technical process of the present invention has great advantages compared with the conventional process.
TABLE 6 sinter composition with 15% iron concentrate fines usage
TABLE 7 sintering index of 15% iron concentrate powder
Example four: the content of the fine iron powder is 20 percent of the sintered mixture
When the amount of the fine iron powder accounts for 20 percent of the proportion of the sintering mixture, the materials are distributed and processed according to the technical scheme. Calculating the proportion PA of the return mine A partRF24.9 percent, part A of the coke powder is PAC2.2%, limestone A part ratio PAS1.8 percent of quicklime A, and part proportion PA of quicklime AL2.7% of CaO and Fe in the adhered particles2O3The total amount was 11.8%.
The mixing time of the raw materials in the intensive mixer was 2min, the granulation time in the cylindrical granulator was 7min, and the mixing granulation time in the cylindrical mixer granulator was 7min, and the obtained sintered ore components and sintering indexes were as shown in table 8 and table 9, respectively. Also, the test results obtained by the conventional sintering method under the test conditions using exactly the same raw materials and ratios are shown in Table 9. As can be seen from the test results, the technical process of the present invention has certain advantages compared with the conventional process.
TABLE 8 sinter composition with 20% iron concentrate fines usage
TABLE 9 sintering index of 20% iron concentrate powder
FIGS. 5, 6 and 7 show graphs comparing the productivity test results, yield test results and drum strength test results of the conventional sintering according to the present invention.
In conclusion, the invention uses the low-silicon iron fine powder to be granulated and pelletized into the return ores with large granularity as the core, and uses the iron fine powder, the fine flux and the fine coke powder as the inner adhesion layer (CaO in the inner adhesion layer accounts for CaO and Fe)2O311-18 percent of the total amount) and takes fine return ores as a special structure of an outer adhesive layer, thereby solving the technical problems that the iron fine powder has poor granulation property and is difficult to granulate and has poor high-temperature sintering property and is difficult to mineralize, and simultaneously, part of coarse-grained coke powder is usedAnd a coarse limestone flux is added (i.e. distributed outside the granulated pellets). Through the technical means, the sintering mineral product and quality index are optimized, and the utilization coefficient of the sintering machine is improved by 1.6-4.7t/m compared with that of the conventional sintering process under the condition of the same raw material structure2D, the sintering yield is improved by 0.8-1.5%, and the drum strength of the sintering ore is improved by 1.6-2.4%.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (3)
1. An efficient iron ore sintering method using low-silicon iron fine powder is characterized by comprising the following steps:
s1, selecting an iron-containing raw material, return ores, dolomite fines, coke powder, limestone powder and quicklime as a sintering mixture, wherein the iron-containing raw material is low-silicon iron fine powder and a mixed ore, the low-silicon iron fine powder accounts for not more than 25% of the sintering mixture by mass, and the low-silicon iron fine powder accounts for not more than 40% of the mixed ore by mass; the mass portion of the return ores in the sintering mixture is 25-30%; the dolomite powder accounts for 3-5% of the mass proportion of the sintering mixture; the coke powder accounts for 2-5% of the mass proportion of the sintering mixture; the limestone powder accounts for 2-4% of the mass proportion of the sintering mixture; the quicklime accounts for 3-5% of the mass of the sintering mixture;
s2, the return fines comprise sinter powders, the sinter powders are the undersize parts of finished sinter powders after being screened before the blast furnace is fed, the granularity is less than 5mm, the return fines are divided into A, B parts, the part A is screened into two parts of more than 1mm size fraction and less than 1mm size fraction through a screening system, and the part B, coke powder, limestone powder, quicklime and dolomite powder enter a cylindrical mixing granulator together with the uniform mixing ores;
s3, dividing the coke powder into A, B parts, sieving the part A into two parts of a size fraction smaller than 0.5mm and a size fraction larger than 0.5mm through a sieving system, and feeding the part B, return ores, limestone powder, quicklime and dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s4, dividing the limestone powder into A, B parts, sieving the part A into two parts of a size fraction smaller than 0.5mm and a size fraction larger than 0.5mm through a sieving system, and feeding the part B, return ores, coke powder, quicklime, dolomite powder and uniformly mixed ores into a cylindrical mixing granulator;
s5, dividing the quicklime into A, B parts, taking out the part A, and feeding the part B, the return ores, the coke powder, the limestone powder and the dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s6, feeding all dolomite powder, return ores, coke powder, limestone powder and dolomite powder and the uniformly mixed ores into a cylindrical mixing granulator;
s7, screening the low-silicon iron fine powder and part A of coke powder to obtain a part with a particle size smaller than 0.5mm, screening part A of limestone powder to obtain a part with a particle size smaller than 0.5mm, and adding part A of quicklime into a powerful mixer, adding water to moisten materials in the process of uniformly mixing, wherein the water content of the materials discharged by the powerful mixer is 2-4%, and the mixing time is 1-3 min;
s8, sieving the return ores of the part A, adding water to prewet the part with the size larger than 1mm, and controlling the water addition amount to be 3-5% of the material moisture;
s9, adding the materials discharged from the intensive mixer and the prewetted return ores with the size fraction larger than 1mm into a cylindrical granulator from a feeding end, sieving part A of the return ores with the size fraction smaller than 1mm, adding the sieved part A of the return ores into the cylindrical granulator from a discharging end, wherein the adding position is 1/3 of the distance from a material falling point to the discharging end, which accounts for the length of the whole cylindrical granulator;
s10, adding the B part of sintering powder, the B part of coke powder, the B part of limestone powder, the B part of quicklime and dolomite powder and the mixed ore into a cylindrical mixing granulator from a feed end, adding the material discharged from the cylindrical granulator, the part A of coke powder which is sieved and is larger than 0.5mm in size fraction, and the part A of limestone powder which is sieved and is larger than 0.5mm in size fraction from a discharge end of the cylindrical mixing granulator, wherein the adding position is 1/3 of the distance from a material falling point to the discharge end, which accounts for the length of the whole cylindrical mixing granulator;
s11, the materials discharged from the cylindrical mixing granulator are sequentially subjected to the processes of distributing, igniting, sintering, cooling and granulating to obtain finished sintered ore for blast furnace use,
in the step S1, SiO in the low-silicon iron fine powder2The mass percentage content is less than 3 percent,
the blended ore in the step S1 contains iron ore powder, pellet and lump ore undersize powder and iron-containing miscellaneous materials, but does not contain low-silicon iron fine powder,
in step S2, the proportions of the return ore portion a and the portion B in the sinter mix are respectively denoted as PARFAnd PBRF，PARFIs calculated by the formula
PBRFThe PA is subtracted from the proportion of the whole return ores in the sintering mixtureRFIn the formula: m (%) is the proportion of the low-silicon iron fine powder in the sintering mixture; n is a proportionality coefficient; a (%) is the proportion of more than 1mm size fraction in the return fines; in the formula, the proportionality coefficient n is determined by the value of m, the value range of m (%) is not higher than 25%, the value range of n is 0.7-1.3, a (%) is 70%, and the function relationship of the proportionality coefficient n and m is as follows: n (m) ═ 0.024m +1.35,
the proportions of the part A and the part B of the coke powder in the sintering mixture in the step S3 are respectively marked as PACAnd PBC，PACThe calculation formula of (2) is as follows: PAC＝0.08m+0.6；PBCThe PA is subtracted from the proportion of the whole coke powder in the sintering mixtureC，
In the step S4, the proportion of the limestone powder A and the proportion of the limestone powder B in the sintering mixture are respectively marked as PASAnd PBS，PASThe calculation formula of (2) is as follows: PAS＝0.05m+0.8；PBSThe PA is subtracted from the proportion of the total limestone powder in the sintering mixtureS，
In the step S5, the proportion of the part A and the part B of the quicklime in the sintering mixture is respectively marked as PALAnd PBL，PALThe calculation formula of (2) is as follows: PAL＝0.125m+0.15；PBLThe PA is subtracted from the proportion of the whole quicklime in the sintering mixtureL。
2. The method for efficiently sintering iron ore using the low-silicon iron concentrate powder according to claim 1, wherein the method comprises the following steps: in the step S9, water is supplemented into the cylindrical granulator in the operation process, the water content of discharged materials of the cylindrical granulator is 4-6%, and the granulation time is 3-8 min.
3. The method for efficiently sintering iron ore using the low-silicon iron concentrate powder according to claim 1, wherein the method comprises the following steps: in the step S10, water is added into the cylinder mixing granulator in the operation process, the water content of the material discharged from the cylinder mixing granulator is 6-8%, and the mixing granulation time is 6-10 min.
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| CN111141642B (en) * | 2020-01-13 | 2022-07-05 | 长沙理工大学 | Method for judging granulation selectivity strength among different iron ore powder particles |
| CN111500855B (en) * | 2020-04-15 | 2022-03-25 | 山西太钢不锈钢股份有限公司 | Method for preparing sintered ore by using CDQ powder and sintered ore prepared by same |
| CN111560516A (en) * | 2020-06-08 | 2020-08-21 | 南开大学 | Sintering mixture and mixing method, sintered ore and sintering method |
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| CN113652547A (en) * | 2021-08-16 | 2021-11-16 | 中南大学 | Method and system for producing double-layer pellets |
| CN114622090B (en) * | 2022-03-14 | 2023-12-19 | 中冶赛迪工程技术股份有限公司 | High-proportion magnetic refined powder sintering method by material surface oxyhydrogen composite blowing |
| CN115491488B (en) * | 2022-09-21 | 2023-07-18 | 宝武集团鄂城钢铁有限公司 | Iron-containing material for sintering with low usage amount of Brazil mixed powder, sintering composition, sintered ore and preparation method of iron-containing material |
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