Preparation method of iron-containing furnace charge for blast furnace

Abstract

The invention discloses a preparation method of an iron-containing furnace charge for a blast furnace. The method comprises the following steps: uniformly mixing an iron-containing raw material with a bonde-1 (containing an organic polymer binder, an active calcium-based substance and an active iron-based substance), then adding a bonde-2 (containing silica sol and water glass) and water, and further uniformly mixing to obtain a mixture; carrying out compression molding on the mixture to obtain a wet block mass; and drying and solidifying the wet block mass to obtain the iron-containing furnace charge. According to the method, by using the special multifunctional binder, efficient forming, rapid consolidation and clean low-carbon preparation of the blast furnace burden from the iron-containing burden can be achieved, the obtained blast furnace burden meets the performance requirements of the blast furnace burden, and the method has important practical significance for achieving the double-carbon strategy in the iron and steel industry.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of iron-containing furnace burden for blast furnace, in particular to a preparation method of iron-containing furnace burden for blast furnace by roller forming-low temperature solidification, and belongs to the field of steel metallurgy. BACKGROUND

[0002] The CO2 emission of the steel industry ranks first in the manufacturing industry, and is the key field to implement the "carbon peak" first. The current mainstream preparation process of iron-containing furnace burden for blast furnace is mainly sintering process and pelletizing process, which all need to go through the process from low temperature to high temperature and then to low temperature. The CO2 emission of the iron sintering and pelletizing process accounts for more than 15% of the total CO2 emission of the steel smelting process, which is the main carbon reduction link for the steel industry to achieve low-carbon and green development.

[0003] The cold briquetting process originated in the 1930s of the 19th century and was used to treat iron ore fines in the late 19th century. It is the earliest method of briquetting fine particle iron-containing materials. However, due to the small production capacity of the briquetting equipment, it is difficult to meet the development of modern steel industry, and has not been able to obtain greater development. In recent years, with the increase of environmental protection pressure and the implementation of carbon emission policy, the cold briquetting process has been widely concerned by domestic and foreign scientific research institutions and production enterprises because the process has no high temperature link, and the process energy consumption and pollutant emission are significantly lower than those of sintering and pelletizing.

[0004] The binder used in the cold briquetting process mainly includes organic, inorganic and composite binders. The organic binder has good bonding effect and good wet briquette performance, but it is expensive and volatile at high temperature, and has no high temperature strength. The inorganic binder is widely available and low in cost, but it still has certain strength at high temperature, but it will introduce impurities and reduce product quality. The composite binder has the advantages of both, and is the key direction of current binder development.

[0005] At present, the cold briquetting process for preparing iron-containing furnace burden for blast furnace mainly uses inorganic binders such as cement, water glass and quicklime, which all have the disadvantages of long solidification time or introduction of many impurities. SUMMARY

[0006] In view of the above-mentioned defects of the existing cold briquetting technology, the purpose of the present application is to provide a preparation method of iron-containing furnace burden for blast furnace, which can realize efficient forming, rapid solidification and clean and low-carbon preparation of iron-containing raw materials by using a special multifunctional binder, and the obtained blast furnace burden meets the performance requirements of blast furnace burden, which has important practical significance for the steel industry to implement the "double carbon" strategy.

[0007] In order to achieve the above technical purpose, the present application provides a preparation method of iron-containing furnace burden for blast furnace, which comprises the following steps:

[0008] 1) mixing the iron-containing raw material with binder-1, then adding binder-2 and water to further mix, to obtain a mixture;

[0009] The binder-1 comprises an organic polymer binder, an active calcium-based substance, and an active iron-based substance;

[0010] The binder-2 comprises silica sol and water glass;

[0011] 2) forming the mixture into a wet briquette by pressing;

[0012] 3) drying and consolidating the wet briquette, and the process is completed.

[0013] The preparation method of the iron-containing furnace charge for blast furnaces provided by the present application adopts a special multifunctional binder, which comprises various components that are coupled with each other and exhibit good binding effects, and can provide mechanical strength for cold-consolidated briquettes at different stages. The binder-1 comprises an organic polymer binder, an active calcium-based substance, and an active iron-based substance. The organic polymer binder can be tightly combined with the iron-containing material in a chemical bond connection mode, can effectively improve the falling strength and compressive strength of the wet briquette, and can be decomposed and volatilized under high-temperature conditions without introducing harmful components. The active calcium-based substance can react with water to generate Ca(OH)2 with strong binding properties, further enhancing the strength of the wet briquette and the dry briquette. During the subsequent drying and consolidation process, Ca(OH)2 can react with CO2 to generate CaCO3, which improves the strength of the briquette through carbonation consolidation. The metallic iron in the active iron-based substance can be rusted and consolidated, and the newly generated iron oxide crystals are tightly interconnected with the iron-containing material, greatly improving the strength of the briquette. The binder-2 mainly comprises silica sol and water glass. These components will form a large number of colloidal particles as the water is removed, which can tightly bind the iron-containing material together, and still have a certain binding effect under the action of high temperature, providing high-temperature strength for the briquette.

[0014] As a preferred scheme, the iron-containing raw material is iron concentrate and / or iron ore powder;

[0015] As a preferred scheme, the particle size of the iron-containing raw material satisfies that the mass ratio of <8 mm particle size is not less than 90%, and the mass ratio of <1 mm particle size is not less than 30%. The iron-containing raw material with different particle size distributions can fill the voids between large particle materials during the subsequent forming process, reducing the porosity of the briquette and increasing the strength of the cold-pressed briquette.

[0016] As a preferred scheme, the mass of the binder-1 is 2-4% of the mass of the iron-containing raw material. If the amount of binder-1 added is too high, the production cost will increase and the iron grade of the briquette will decrease. If the amount of binder-1 added is too low, the binding performance is poor, and the falling strength and compressive strength of the wet briquette cannot meet the production requirements.

[0017] As a preferred scheme, the binder-1 is composed of organic polymer binder, active calcium-based substance and active iron-based substance in a mass percentage of 30%-35%: 45%-50%: 15%-25%. The component ratio of the binder-1 is optimized, wherein, when the content of the organic polymer binder is too high, on the one hand, the cost of the binder is greatly increased, and on the other hand, the porosity of the briquette is increased and the strength of the briquette is decreased due to the easy decomposition and volatilization of the organic polymer substance at high temperature; when the content of the organic polymer binder is too low, it is difficult to ensure that the compressive strength and the falling strength of the wet briquette meet the performance requirements of the production process; when the content of the active calcium-based substance is too high, the time required for the carbonation and solidification process is greatly prolonged due to the high content of CaO, thereby affecting the production efficiency; when the content of the active calcium-based substance is too low, the strength of the wet briquette is affected; when the content of the active iron-based substance is too high, on the one hand, the cost of the binder is increased, and on the other hand, the time required for the rustification and solidification is increased, thereby affecting the production efficiency; when the content of the active iron-based substance is too low, on the one hand, the strength of the wet briquette is affected, and on the other hand, the iron grade of the briquette is reduced.

[0018] As a preferred scheme, the organic polymer binder is at least one of sodium carboxymethyl cellulose, corn starch and sodium carboxymethyl starch. The preferred organic polymer binder can be closely combined with the iron-containing material in a chemical bond connection mode, improve the bonding strength between the iron-containing raw materials, and at the same time, improve the hydrophilicity of the surface of the iron-containing raw material, thereby effectively improving the falling strength and the compressive strength of the wet briquette, and the organic polymer binder can be decomposed and volatilized under high temperature conditions without introducing harmful components.

[0019] As a preferred scheme, the active calcium-based substance is quicklime and / or slaked lime, and the mass content of f-CaO is >85%. The particle size of the active calcium-based substance is <0.5mm.

[0020] As a preferred scheme, the active iron-based substance is metallic iron powder, and the mass content of MFe is >85%. The active iron-based substance is obtained by fine grinding and magnetic separation of the metallized briquette produced by a direct reduction process such as a rotary hearth furnace or a rotary kiln, and the particle size is <1mm.

[0021] The active calcium-based substance and the active iron-based substance of the present application are both components required for blast furnace charge production.

[0022] As a preferred scheme, the mass of the binder-2 is 3-6% of the mass of the iron-containing raw material. When the addition amount of the binder-2 is too high, too many gangue components are introduced, thereby reducing the iron grade of the briquette; and when the addition amount is too low, the bonding performance is poor, thereby affecting the high-temperature strength of the briquette.

[0023] As a preferred scheme, the binder-2 is composed of silica sol and water glass according to 40%-50%: 50%-60%. The cost of silica sol is higher than that of water glass, and when the content of silica sol is too high, the cost of the binder will increase; when the content is too low, the binding effect is poor, which affects the strength of the briquette. The binding performance of water glass is good, but it cannot be introduced too high, because the introduction of sodium element will affect the blast furnace smelting, so the amount thereof needs to be controlled within a proper proportion range.

[0024] As a preferred scheme, the SiO2 mass content in the silica sol is 20%-40%.

[0025] As a preferred scheme, the modulus of the water glass is 2.2-3.8, and the solid mass content is 30%-42%.

[0026] The binder-1 adopted in the present application is a solid binder, and the binder-2 is a liquid binder. In the mixing process with the iron-containing raw material, the solid binder is mixed with the iron-containing raw material first, and then mixed with the liquid binder, so that the mixing uniformity between the iron-containing raw material and the binder can be improved. The viscosity of the liquid binder is large, and if it is mixed with the iron-containing raw material first, it will hinder the further mixing uniformity of the solid binder and the iron-containing raw material.

[0027] As a preferred scheme, the water mass content in the mixed material is 6.5%-8.5%.

[0028] As a preferred scheme, the pressing forming is realized by using a high-pressure roller ball machine, the linear pressure in the pressing forming process is 0.5-1 t / mm, the shape of the formed wet briquette is flat round, and the size is Φ20 mm*10 mm-Φ35 mm*25 mm. The high-pressure roller ball machine can realize the rapid pressing forming of the mixed material.

[0029] As a preferred scheme, the drying is realized by using a hot air drying method, the hot air temperature is 100-200 DEG C, and the drying time is 12-20 min. The preferred drying equipment is a steel belt machine, a chain grate machine or a chain plate type drying machine, and the thickness of the laid material layer is not more than 300 mm. The hot air in the drying process comes from the hot air reuse in the solidification process.

[0030] As a preferred scheme, the solidification is realized by using a hot air coupling microwave heating solidification, the CO2 volume content in the hot air is not less than 5%, the microwave heating solidification temperature is 200-350 DEG C, and the time is 5-10 min. The heat of the hot air comes from the combustion of low-calorific-value solid waste, low-calorific-value flue gas (blast furnace gas and coke oven gas, etc.) or biomass. The microwave heating equipment is conventional in the prior art, and there is no special requirement.

[0031] The drying of the present application adopts hot air drying, solidification hot air coupled with microwave heating, and efficient coupling of drying-solidification process, low processing temperature, less carbon emission, and short solidification time. The highest temperature in the whole process does not exceed 350 DEG C, low calorific value solid waste, low calorific value flue gas (blast furnace gas and coke oven gas, etc.) or biomass is used as fuel for combustion heating, no fossil fuel is used, CO2 generation is less, and in the drying and solidification process, part of CO2 can be absorbed through carbonation and solidification, further reducing CO2 emission. Microwave uses clean energy green electricity, no CO2 emission. The temperature of the hot air drying process is relatively low, and about 70% of the water can be removed, the temperature inside the briquette is lower than the outside, and the water removal rate inside is lower than that outside. The temperature of the hot air-microwave solidification process is relatively high, and the microwave has the characteristics of uniform heating, which can quickly remove the water in the briquette. The hot air is reused to the drying process after the solidification process, which can further improve the heat utilization efficiency and reduce the amount of waste gas generated in the whole process. In addition, the hot air and microwave in the drying and solidification process can be efficiently coupled with various components in the binder, and the briquette strength is greatly increased. For example, in the drying and solidification process, f-CaO and Ca(OH)2 in the binder-1 will react with CO2 in the hot air to generate CaCO3, and the briquette strength is improved through carbonation and solidification; the binder-2 will form smaller and more uniform colloidal particles under the action of microwave, so that the number of binding sites in the briquette increases, and the briquette strength increases significantly.

[0032] The method for preparing the iron-containing furnace charge for blast furnace provided by the present application comprises the following specific steps:

[0033] (1) mixing and mixing, adding 2-4% of binder-1 in total weight of iron-containing raw materials in the iron-containing raw materials; wherein the iron-containing raw materials are one or more of iron concentrate, iron ore powder, wherein the proportion of particle size <8mm of the iron-containing raw materials is not less than 90%, and the content of <1mm particle size is not less than 30%; the binder-1 is a solid composite binder, which is composed of 30-35% of organic polymer binder, 45-50% of high-activity calcium-based substance and 15-25% of high-activity iron-based substance; the organic polymer binder is one or more of sodium carboxymethyl cellulose, corn starch, sodium carboxymethyl starch, etc.; the high-activity calcium-based substance is one or more of quicklime or slaked lime, with f-CaO content >85% and particle size <0.5mm; the high-activity iron-based substance is metallic iron powder, MFe >85%, which is obtained by fine grinding and magnetic separation of the metallized pellets produced by direct reduction process such as rotary hearth furnace or rotary kiln, with particle size <1mm; then mixing uniformly, further mixing after adding 2-4% of binder-2 and water in total weight of iron-containing raw materials; wherein the binder-2 is a liquid inorganic binder, which is composed of 40-50% of silica sol and 50-60% of water glass; the SiO2 content in the silica sol is 20-40%; the modulus of the water glass is 2.2-3.8, and the solid content is 30-42%; finally obtaining the mixed material with moisture content of 6.5-8.5%;

[0034] (2) pressing forming, using high-pressure roller press ball machine with linear pressure of 0.5-1t / mm to press form, obtaining flat round wet briquettes with size of Φ20mm*10mm-Φ35mm*25mm;

[0035] (3) drying and solidification, laying the wet briquettes on the drying and solidification equipment with layer thickness not more than 300mm; wherein the drying equipment is one of steel belt machine, chain grate machine, chain plate dryer, etc.; first, hot air drying process with temperature of 100-200℃ and time of 12-20min; wherein the hot air comes from the hot air reuse of the solidification process; then, hot air coupling microwave solidification process with temperature of 200-350℃ and time of 5-10min; wherein the heat of the hot air comes from low-calorific-value solid waste, low-calorific-value flue gas (blast furnace gas and coke oven gas, etc.) or biomass combustion heating, and the CO2 content in the hot air is not less than 5%; finally obtaining the iron-containing burden material with mass meeting the requirements of blast furnace.

[0036] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0037] (1) The binder used in the preparation process of the blast furnace iron-containing burden of the present application is non-toxic and harmless, widely available, and low in cost. The organic high molecular polymer in the binder-1 will decompose and volatilize under high temperature conditions, and will not introduce harmful components; and the high-activity calcium-based powder and high-activity iron-based powder are all components required for blast furnace production. Although Na element is harmful to the blast furnace, the addition amount of binder-2 and water glass in binder-2 is small, so the introduction amount of Na is very low, and the influence on blast furnace smelting is very small.

[0038] (2) The various components in the binder in the preparation process of the blast furnace iron-containing burden of the present application are coupled with each other, and show good comprehensive binding effect, which can provide strength for the cold-solidified briquettes at different stages of the whole process. The organic high molecular polymer in the binder-1 is tightly combined with the iron-containing material in the form of chemical bond, which can effectively improve the falling strength and compressive strength of the wet briquettes; the high-activity calcium-based powder can react with water to generate Ca(OH)2 with strong binding property, further enhancing the strength of the wet briquettes and dry briquettes; the metallic iron in the high-activity iron-based powder will be rusted and solidified, and the newly generated iron oxide crystals are tightly interconnected with the iron-containing material, greatly improving the strength of the briquettes. The binder-2 will form a large number of colloidal particles with the removal of water, which will tightly bind the iron-containing material together, and still have certain binding effect under high temperature, which can provide high temperature strength for the briquettes.

[0039] (3) The drying-solidification process in the preparation process of the blast furnace iron-containing burden of the present application is highly efficient and coupled, with low processing temperature, less carbon emission, and short solidification time. The highest temperature in the whole process is not more than 350℃, low-calorific-value solid waste, low-calorific-value flue gas (blast furnace gas and coke oven gas, etc.) or biomass is used as fuel for heating, no fossil fuel is used, the amount of CO2 generated is less, and part of the CO2 can be absorbed through carbonation and solidification during the drying and solidification process, further reducing the amount of CO2 emission. The microwave uses clean energy green electricity, with no CO2 emission. The temperature in the hot air drying process is relatively low, and about 70% of the water can be removed, the temperature inside the briquettes is lower than the outside, and the water removal rate inside is lower than that outside. The temperature in the hot air-microwave solidification process is relatively high, and the microwave has the characteristics of uniform heating, which can quickly remove the water inside the briquettes at this stage. The hot air is reused to the drying process after the solidification process, which can further improve the heat utilization efficiency and reduce the amount of waste gas generated in the whole process.

[0040] (4) In the drying and solidification process of the preparation process of the blast furnace iron-containing burden of the present application, the hot air and the microwave in the drying and solidification process can be coupled with various components in the binder to greatly increase the strength of the briquettes. In the drying and solidification process, f-CaO and Ca(OH)2 in the binder-1 will react with CO2 in the hot air to generate CaCO3, thereby improving the strength of the briquettes through carbonation solidification; the binder-2 will form smaller and more uniformly dispersed colloidal particles under the action of the microwave, so that the number of binding sites in the briquettes increases, and the strength of the briquettes is greatly increased.

[0041] In summary, by implementing the method of the present application, the blast furnace burden obtained has a compressive strength of not less than 2500 N / P and a drum index (+6.3 mm) of not less than 78%, which meets the performance requirements of the blast furnace burden. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 The flow chart of the new process. DETAILED DESCRIPTION

[0043] In order to facilitate the understanding of the present application, the following will combine the preferred embodiments to describe the present application more comprehensively and in detail, but the protection scope of the present application is not limited to the following specific embodiments.

[0044] Unless otherwise defined, all professional terms used in the following have the same meaning as generally understood by those skilled in the art. The patent terms used in this paper are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application.

[0045] Unless otherwise specified, the various reagents and raw materials used in the present application are commercially available or can be prepared by known methods.

[0046] Example 1

[0047] The iron-containing raw material is composed of 40% iron concentrate and 60% iron ore powder, wherein the proportion of the iron-containing raw material with a particle size of <8 mm is 92%, and the content of the particle size of <1 mm is 31%; 2.5% of the total weight of the iron-containing raw material is added as a binder-1, wherein the binder-1 is a solid composite binder composed of 32% carboxymethyl cellulose sodium, 45% quicklime and 23% metallic iron powder, the content of f-CaO in the quicklime is 87%, the particle size is <0.5 mm, the MFe of the metallic iron powder is 85%, and the particle size is <1 mm; then the mixture is uniformly mixed, 3.5% of the total weight of the iron-containing raw material is added as a binder-2 and water, and the mixture is further mixed, wherein the binder-2 is a liquid inorganic binder composed of 40% silica sol and 60% water glass, the content of SiO2 in the silica sol is 25%, the modulus of the water glass is 2.4, and the solid content is 33%; finally, the mixture with a moisture content of 6.7% is obtained; a high-pressure roller press ball machine with a linear pressure of 0.6 t / mm is used for pressing and forming to obtain a flat round wet briquette with a size of Φ20 mm×10 mm; the wet briquette is laid on a steel belt machine for drying and solidification, and the thickness of the material layer is 280 mm, wherein the hot air in the drying process comes from the reuse of the hot air in the solidification process, the drying temperature is 120°C, and the time is 20 min; the solidification process is a coupling effect of hot air and microwave, the heat of the hot air comes from the heat supply of low-calorific-value solid waste combustion, the content of CO2 in the hot air is 6%, the solidification temperature is 340°C, and the time is 6 min; finally, the iron-containing blast furnace burden with a mass meeting the requirements of the blast furnace is obtained, the compressive strength of the wet briquette is 70 N / P, the falling strength is 7 times / (0.5 m·piece), the compressive strength of the briquette after solidification is 2550 N / P, and the drum index (+6.3 mm) is 81%.

[0048] Example 2

[0049] The iron-containing raw material is composed of 60% iron concentrate and 40% iron ore powder, wherein the proportion of the iron-containing raw material with a particle size of <8mm is 90%, and the content of the particle size of <1mm is 35%; 3% of the total weight of the iron-containing raw material is added as a binder-1, wherein the binder-1 is a solid composite binder, which is composed of 34% sodium carboxymethyl cellulose, 47% quicklime and 19% metal iron powder, the content of f-CaO in the quicklime is 85%, the particle size is <0.5mm, the MFe of the metal iron powder is 87%, and the particle size is <1mm; then the mixture is uniformly mixed, 3% of the total weight of the iron-containing raw material is further added as a binder-2 and water, and the mixture is further mixed, wherein the binder-2 is a liquid inorganic binder, which is composed of 45% silica sol and 55% water glass, the content of SiO2 in the silica sol is 29%, the modulus of the water glass is 2.8, and the solid content is 35%, finally the mixture with a moisture content of 7.3% is obtained; the wet briquetting machine with a linear pressure of 0.8t / mm is used for pressing and forming, and the flat round wet briquettes with a size of Φ25mm*15mm are obtained; the wet briquettes are arranged on the steel belt machine for drying and solidification, and the thickness of the material layer is 250mm, wherein the hot air in the drying process is reused from the hot air in the solidification process, the drying temperature is 140℃, and the time is 15min; the solidification process is the coupling effect of hot air and microwave, the heat of the hot air is from the heat supply of the blast furnace gas combustion, the content of CO2 in the hot air is 7%, the solidification temperature is 280℃, and the time is 8min; finally the iron-containing charge with a quality meeting the requirements of the blast furnace is obtained. After the present application is adopted, compared with example 1, the compressive strength of the wet briquette is 80N / P, the falling strength is 10 times / (0.5m*piece), the compressive strength of the briquette after solidification is 2710N / P, and the drum index(+6.3mm) is 84%.

[0050] Example 3

[0051] The iron-containing raw material is composed of 60% iron concentrate and 40% iron ore powder, wherein the proportion of the iron-containing raw material with a particle size of <8mm is 91%, and the content of the particle size of <1mm is 45%; 3.8% of the total weight of the iron-containing raw material is added as a binder-1, wherein the binder-1 is a solid composite binder composed of 30% sodium carboxymethyl cellulose, 50% quicklime and 20% metallic iron powder, the content of f-CaO in the quicklime is 88%, the particle size is <0.5mm, the MFe of the metallic iron powder is 90%, and the particle size is <1mm; then the mixture is uniformly mixed, 3.3% of the total weight of the iron-containing raw material is further added as a binder-2 and water, and the mixture is further mixed, wherein the binder-2 is a liquid inorganic binder composed of 50% silica sol and 50% water glass, the content of SiO2 in the silica sol is 31%, the modulus of the water glass is 3.1, and the solid content is 37%, and finally the mixture with a moisture content of 7.3% is obtained; a high-pressure roller press ball machine with a linear pressure of 1t / mm is used for pressing and forming, and a flat round wet briquette with a size of Φ30mm*20mm is obtained; the wet briquette is laid on a steel belt machine for drying and solidification, and the thickness of the material layer is 270mm, wherein the hot air in the drying process comes from the reuse of the hot air in the solidification process, the drying temperature is 180℃, and the time is 12min; the solidification process is a coupling effect of hot air and microwave, the heat of the hot air comes from the combustion of coke gas, the content of CO2 in the hot air is 7%, the solidification temperature is 250℃, and the time is 9min; finally, the iron-containing blast furnace burden with a quality meeting the requirements of the blast furnace is obtained. After the present application is adopted, compared with example 2, the compressive strength of the wet briquette is 85N / P, the falling strength is 12 times / (0.5m*piece), the compressive strength of the briquette after solidification is 2850N / P, and the drum index(+6.3mm) is 87%.

[0052] Comparative Example 1

[0053] The iron-containing raw material is composed of 40% iron concentrate and 60% iron ore powder, wherein the proportion of the iron-containing raw material with a particle size of <8 mm is 92%, and the content of the <1 mm particle size is 31%; 2.5% of the total weight of the iron-containing raw material is added as a binder-1, wherein the binder-1 is a solid composite binder composed of 32% carboxymethyl cellulose sodium and 68% metal iron powder, the metal iron powder MFe is 85%, and the particle size is <1 mm; then the mixture is uniformly mixed, 3.5% of the total weight of the iron-containing raw material is further added as a binder-2 and water, and the mixture is further mixed, wherein the binder-2 is a liquid inorganic binder composed of 40% silica sol and 60% water glass, the SiO2 content in the silica sol is 25%, the modulus of the water glass is 2.4, and the solid content is 33%, and finally the mixture with a moisture content of 6.7% is obtained; a high-pressure roller press ball machine with a linear pressure of 0.6 t / mm is used for pressing and forming, and a flat round wet briquette with a size of Φ20 mm×10 mm is obtained; the wet briquette is laid on a steel belt machine for drying and solidification, and the thickness of the material layer is 280 mm, wherein the hot air in the drying process comes from the reuse of the hot air in the solidification process, the drying temperature is 120°C, and the time is 20 min; the solidification process is the coupling effect of hot air and microwave, the heat of the hot air comes from the heat supply of low-calorific-value solid waste combustion, the CO2 content in the hot air is 6%, the solidification temperature is 340°C, and the time is 6 min; finally, the iron-containing charge with a mass meeting the requirements of blast furnace is obtained. Compared with Comparative Example 1 and Example 1, the only difference is that no active calcium-based substance is added, the wet briquette compressive strength is 40 N / P, the drop strength is 3 times / (0.5 m·piece), the compressive strength of the briquette after solidification is 1940 N / P, and the drum index(+6.3 mm) is 69%.

[0054] Comparative Example 2

[0055] The iron-containing raw material is composed of 60% iron concentrate and 40% iron ore powder, wherein the proportion of the iron-containing raw material with a particle size of <8 mm is 90%, and the content of the <1 mm particle size is 35%; 3% of the total weight of the iron-containing raw material is added as a binder-1, wherein the binder-1 is a solid composite binder composed of 34% sodium carboxymethyl cellulose, 47% quicklime and 19% metallic iron powder, the f-CaO content in the quicklime is 85%, the particle size is <0.5 mm, the MFe of the metallic iron powder is 87%, and the particle size is <1 mm; then the mixture is uniformly mixed, a certain proportion of water is added and further mixed, and finally a mixture with a moisture content of 7.3% is obtained; a high-pressure roller press ball machine with a linear pressure of 0.8 t / mm is used for pressing and forming to obtain a flat round wet briquette with a size of Φ25 mm×15 mm; the wet briquette is laid on a steel belt machine for drying and solidification, and the thickness of the material layer is 250 mm, wherein the hot air in the drying process comes from the reuse of the hot air in the solidification process, the drying temperature is 140℃, and the time is 15 min; the solidification process is the coupling effect of hot air and microwave, the heat of the hot air comes from the heat supply of blast furnace gas combustion, the CO2 content in the hot air is 7%, the solidification temperature is 280℃, and the time is 8 min; finally, the iron-containing charge with a mass meeting the requirements of blast furnace is obtained. Compared with Example 2, the only difference of Comparative Example 2 is that no binder-2 is added, the wet briquette compressive strength is 35 N / P, the drop strength is 2.5 times / (0.5 m·piece), the compressive strength of the briquette after solidification is 1620 N / P, and the drum index(+6.3 mm) is 61%.

[0056] Comparative Example 3

[0057] The iron-containing raw material is composed of 60% iron concentrate and 40% iron ore powder, wherein the proportion of the iron-containing raw material with a particle size of <8 mm is 91%, and the content of the particle size of <1 mm is 45%; 3.8% of the total weight of the iron-containing raw material is added as a binder-1, wherein the binder-1 is a solid composite binder composed of 30% sodium carboxymethyl cellulose, 50% quicklime and 20% metallic iron powder, the content of f-CaO in the quicklime is 88%, the particle size is <0.5 mm, the MFe of the metallic iron powder is 90%, and the particle size is <1 mm; then the mixture is uniformly mixed, 3.3% of the total weight of the iron-containing raw material is further added as a binder-2 and water, and the mixture is further mixed, wherein the binder-2 is a liquid inorganic binder composed of 50% silica sol and 50% water glass, the content of SiO2 in the silica sol is 31%, the modulus of the water glass is 3.1, and the solid content is 37%, and finally the mixture with a moisture content of 7.3% is obtained; a high-pressure roller press is used for pressing and forming, the linear pressure of the high-pressure roller press is 1 t / mm, and a flat round wet briquette with a size of Φ30 mm×20 mm is obtained; the wet briquette is laid on a steel belt machine for drying and solidification, the thickness of the material layer is 270 mm, wherein the hot air in the drying process comes from the reuse of the hot air in the solidification process, the drying temperature is 180℃, and the drying time is 12 min; the solidification process is hot air solidification, the heat of the hot air comes from the combustion of coke oven gas, the content of CO2 in the hot air is 7%, the solidification temperature is 250℃, and the solidification time is 9 min; finally, the iron-containing burden with a mass meeting the requirements of blast furnace is obtained. Compared with Example 3, the only difference of Comparative Example 3 is that the microwave solidification measure is not implemented, the compressive strength of the wet briquette is 70 N / P, the falling strength is 10 times / (0.5 m·piece), the compressive strength of the briquette after solidification is 1950 N / P, and the drum index(+6.3 mm) is 79%.

Claims

1. A method for preparing an iron-containing charge for a blast furnace, characterized in that: The following steps are involved: 1) After mixing the iron-containing raw material and binder-1, binder-2 and water are added and further mixed to obtain a mixture; The binder-1 comprises an organic polymer binder, an active calcium-based substance and an active iron-based substance; The binder-2 comprises silica sol and water glass; 2) forming the mixture by compression to obtain a wet mass; 3) The wet mass is dried and solidified to obtain the product.

2. The method for preparing an iron-containing charge for a blast furnace according to claim 1, wherein: The iron-containing raw material is iron concentrate and / or iron ore powder; The particle size of the iron-containing raw material satisfies the following requirements: the mass proportion of particle size <8 mm is not less than 90%, and the mass proportion of particle size <1 mm is not less than 30%.

3. The method for preparing an iron-containing charge for a blast furnace according to claim 1, wherein: The mass of the binder-1 is 2-4% of the mass of the iron-containing raw material; The binder-1 is composed of an organic polymer binder, an active calcium-based substance, and an active iron-based substance in a mass percentage of 30% to 35%: 45% to 50%: 15% to 25%.

4. The method for preparing an iron-containing charge for a blast furnace according to claim 3, wherein: The organic polymer binder is at least one of sodium carboxymethyl cellulose, corn starch, and sodium carboxymethyl starch; the active calcium-based substance is quicklime and / or slaked lime, and the f-CaO mass content is greater than 85%; The active iron-based material is metallic iron powder, and the MFe mass content is greater than 85%.

5. The method for preparing an iron-containing charge for a blast furnace according to claim 1 or 3, characterized in that: The mass of the binder-2 is 3-6% of the mass of the iron-containing raw material; The binder-2 is composed of silica sol and water glass in a ratio of 40% to 50%: 50% to 60%.

6. The method for preparing an iron-containing charge for a blast furnace according to claim 5, wherein: The mass content of SiO2 in the silica sol is 20% to 40%; The modulus of the water glass is 2.2-3.8, and the solid mass content is 30%-42%.

7. The method for preparing an iron-containing charge for a blast furnace according to claim 1, wherein: The moisture content of the mixture is 6.5% to 8.5%.

8. The method for preparing an iron-containing charge for a blast furnace according to claim 1, wherein: The pressing and forming is achieved by using a high-pressure roller pelletizing machine. The linear pressure during the pressing and forming process is 0.5 to 1 t / mm. The formed wet lumps are oblate in shape and have a size of Φ20mm×10mm to Φ35mm×25mm.

9. The method for preparing an iron-containing charge for a blast furnace according to claim 1, wherein: The drying is carried out by hot air drying, the hot air temperature is 100-200° C., and the drying time is 12-20 minutes.

10. The method for preparing an iron-containing charge for a blast furnace according to claim 1, wherein: The consolidation is carried out by hot air coupled with microwave heating, the volume content of CO2 in the hot air is not less than 5%, the microwave heating consolidation temperature is 200-350°C, and the time is 5-10 minutes.

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