阅读说明：本技术 一种铁矿烧结生物质燃料及其制备方法和应用 (Iron ore sintering biomass fuel and preparation method and application thereof ) 是由 季志云 范晓慧 甘敏 李浩锐 倪佳苗 陈许玲 黄晓贤 袁礼顺 黄斌斌 武钰峰 吕 于 2019-10-10 设计创作，主要内容包括：本发明公开了一种铁矿烧结生物质燃料及其制备方法和应用。该方法是将生物质粉末与选铁尾矿渣-硅石尾矿渣混合粉末混匀后,压制成生物质颗粒；所述生物质颗粒置于保护气氛下依次进行低温预处理及高温炭化处理,即得热值为26～33MJ/kg、挥发分0.5～3％、比表面积为10～25m<Sup>2</Sup>/g、孔隙率为15～25％、视密度为1.5～2.2g/cm<Sup>3</Sup>的高品质生物质燃料,该生物质燃料充分利用矿渣中惰性组分SiO<Sub>2</Sub>弱化生物质燃料热化学反应活性、铁氧化物促进挥发分高效裂解的综合效应,可高比例替代化石燃料的生物质燃料使用,实现从源头上高效减排SOx、NOx、CO<Sub>2</Sub>。(The invention discloses an iron ore sintering biomass fuel, and a preparation method and application thereof. Uniformly mixing biomass powder and iron-dressing tailing slag-silica tailing slag mixed powder, and pressing the mixture into biomass particles; the biomass particles are sequentially subjected to low-temperature pretreatment and high-temperature carbonization treatment under a protective atmosphere to obtain the biomass particles with the heat value of 26-33 MJ/kg, the volatile component of 0.5-3% and the specific surface area of 10-25 m 2 A porosity of 15-25%, and an apparent density of 1.5-2.2 g/cm 3 The high-quality biomass fuel fully utilizes the inert component SiO in the slag 2 The comprehensive effect of the thermochemical reaction activity of the biomass fuel and the promotion of the high-efficiency cracking of volatile matters by the iron oxide is weakened, the biomass fuel of fossil fuel can be replaced at a high proportion, and the high-efficiency emission reduction of SOx, NOx and CO from the source is realized 2 。)

1. A method for preparing iron ore sintering biomass fuel by synergistic recycling of tailing slag and waste biomass is characterized by comprising the following steps: uniformly mixing biomass powder and iron-dressing tailing slag-silica tailing slag mixed powder, and pressing into biomass particles; and sequentially carrying out low-temperature pretreatment and high-temperature carbonization treatment on the biomass particles in a protective atmosphere to obtain the biomass particle.

2. The method for preparing the iron ore sintering biomass fuel by the synergistic recycling of the tailing slag and the waste biomass as claimed in claim 1, wherein the method comprises the following steps:

the biomass comprises at least one of agricultural wastes and forestry processing wastes;

the main component of the mixed powder of the iron-dressing tailing slag and the silica tailing slag is SiO₂And iron oxides; the main components by mass percentage are as follows: 60-80% of silicon dioxide and 20-40% of ferric oxide.

3. The method for preparing the iron ore sintering biomass fuel by the synergistic resource utilization of the tailing slag and the waste biomass as claimed in claim 1 or 2, characterized in that: the mass percentage of the biomass powder to the mixed powder of the iron-selecting tailing slag and the silica tailing slag is 96-99.5%: 0.5-4%.

4. The method for preparing the iron ore sintering biomass fuel by the synergistic resource utilization of the tailing slag and the waste biomass as claimed in claim 3, wherein the method comprises the following steps:

the particle size of the biomass powder meets the mass percentage content of 0.1-1 mm particle size not less than 80%;

the particle size of the iron-selecting tailing slag-silica tailing slag mixed powder meets the mass percentage content of 0-0.01 mm particle size not less than 90%.

5. The method for preparing the iron ore sintering biomass fuel by the synergistic recycling of the tailing slag and the waste biomass as claimed in claim 1, wherein the method comprises the following steps: the pressing process comprises the following steps: the molding is assisted by a mold, and the pressure is 300-1000 kg/cm³The time is 0.5-2.5 min, the temperature range of the die is room temperature-150 ℃, and the particle size of the press forming is 3-5 mm.

6. The method for preparing the iron ore sintering biomass fuel by the synergistic recycling of the tailing slag and the waste biomass as claimed in any one of claims 1 to 5, wherein the method comprises the following steps:

the low-temperature pretreatment process comprises the following steps: heating to 200-300 ℃ at a heating rate of 15-25 ℃/min, and keeping the temperature for 30-60 min;

the high-temperature carbonization treatment process comprises the following steps: heating to 600-800 ℃ at a heating rate of 2-8 ℃/min, and preserving the heat for 15-30 min.

7. The iron ore sintering biomass fuel is characterized in that: the preparation method of any one of claims 1 to 6.

8. The iron ore sintering biomass fuel according to claim 7, characterized in that: the combustion heat value of the iron ore sintering fuel is 26-33 MJ/kg, the volatile component is 0.5-3%, and the specific surface area is 10-25 m²A porosity of 15-25%, and an apparent density of 1.5-2.2 g/cm³。

9. The use of the iron ore sintering biomass fuel according to claim 7 or 8, characterized in that: replacing fossil fuels for iron ore sintering.

10. The use of the iron ore sintering biomass fuel according to claim 9, characterized in that: and replacing 40-70% of fossil fuel with constant carbon content for sintering iron ore.

Technical Field

The invention relates to a biomass sintering fuel, in particular to an iron ore sintering fuel prepared by utilizing tailing slag and waste biomass for cooperative recycling and a method thereof, and also relates to a method for replacing fossil fuel with the biomass sintering fuel to realize emission reduction, belonging to the technical field of sintering in the field of ferrous metallurgy.

Background

In the production process of iron and steel enterprises, the energy consumption of a sintering process accounts for about 10% of the total energy consumption, wherein the consumption of solid fuel accounts for about 80% of the process energy consumption. The solid fuel consumed by the traditional sintering is mainly anthracite powder and pulverized coke powder. At present, the world energy form is increasingly severe, the price of fossil fuel is continuously increased, and the sintering cost is high; while combustion of fossil fuels produces large amounts of NO_XSOx and CO₂The environmental pollution problem is becoming more serious. According to the 2019 ultra-low emission requirement of the steel sintering flue gas, the hourly average values of the emission concentrations of the particulate matters, the sulfur dioxide and the nitrogen oxides in the head flue gas of the sintering machine are respectively not higher than 10, 35 and 50mg/m³The average discharge concentration of the iron and steel enterprises reaching the ultralow discharge is more than 95 percent of the time period per monthThe degree satisfies the above-mentioned index. But at present, NOx and SO in sintering flue gas₂The average discharge concentration exceeds 200mg/m³There is a large gap with the requirement for ultra-low emissions.

The biomass energy is a general term of organic combustible generated by plants through photosynthesis, has low sulfur and nitrogen contents, absorbs carbon dioxide in the growing process and discharges carbon dioxide in the combustion process approximately equal, and is clean and renewable energy. It is estimated that about 1600 million tons of biomass is produced by photosynthesis on earth every year, and the abundantly usable parts include agricultural and forestry surplus waste, forestry waste, and processing waste, etc., and the energy contained in these solid wastes is about 5 times of the total energy consumption in the world at present, but only a small part is used. If the part of energy can be utilized in the steel sintering process, the pollutant emission of the sintering process can be greatly reduced.

Scholars at home and abroad carry out a great deal of research work on the feasibility of using biomass fuel to replace fossil fuel for sintering, and the fact that the activity of the thermochemical reaction of the biomass fuel is obviously higher than that of the fossil fuel is relatively consistently found, when the proportion of the replaced coke powder exceeds 20%, the matching between the heat transfer front and the combustion front speed can be damaged, the highest temperature of a sinter bed is reduced, the high-temperature retention time is shortened, and the strength of sinter is reduced, and the yield is reduced. Because the biomass has high reaction activity, insufficient combustion is aggravated, and part of the biomass can also react prematurely to generate CO which enters the flue gas; the biomass fuel prepared by the conventional method has high volatile content, but when the combustion front reaches, the biomass fuel is pyrolyzed and enters flue gas, so that a large amount of heat is wasted, and secondary pollution is generated.

Disclosure of Invention

The method aims at the defect that the reactivity difference between the biomass fuel for iron ore sintering and fossil fuel in the prior art is large in the pyrolysis process, so that fuel combustion is not synchronous in the sintering process. The invention aims to provide a biomass fuel with compact structure, low volatile content and low thermochemical reaction activity, which is particularly suitable for the sintering process of iron ores and can greatly improve the replacement proportion of fossil fuels.

The second purpose of the invention is to provide a method for preparing biomass sintering biomass fuel by using the cooperation of tailing slag and waste biomass, the method has simple steps, the raw material is derived from waste, and the resource utilization of solid waste is really realized.

The third purpose of the invention is to provide an application of the biomass sintering fuel in iron ore sintering, wherein the biomass sintering fuel can replace fossil fuel at a high ratio, the pollutant emission of sintering flue gas is greatly reduced, and the sintering cost is reduced.

In order to realize the technical purpose, the invention provides a method for preparing iron ore sintering biomass fuel by synergistic recycling of tailing slag and waste biomass, which is characterized in that biomass powder and mixed powder of iron-selecting tailing slag-silica tailing slag are uniformly mixed and pressed into biomass particles; and sequentially carrying out low-temperature pretreatment and high-temperature carbonization treatment on the biomass particles in a protective atmosphere to obtain the biomass particle.

Preferably, the biomass comprises at least one of agricultural waste, forestry processing waste, hard fruit pits and fruit shells.

Preferably, the main component of the mixed powder of iron-dressing tailings and silica tailings is SiO₂And iron oxides; the main components by mass percentage are as follows: 60-80% of silicon dioxide and 20-40% of ferric oxide. The iron separation tailing slag is tailing after natural iron ore separation. Silica tailings are tailings after silica beneficiation.

According to the preferable scheme, the biomass powder and the iron-dressing tailing slag-silica tailing slag mixed powder are 96-99.5% by mass: 0.5-4%. The invention will be rich in SiO₂The inert fine SiO is introduced into the biomass fuel by the tailing slag₂The particles occupy the active sites of the biomass fuel, reduce the thermochemical reaction activity of the biomass fuel, and have SiO with a Si-O tetrahedral structure₂And a stable network structure can be formed with the C-C chain, so that the difference of the reactivity of the biomass fuel and the fossil fuel is reduced. The invention introduces the iron oxide component to prepare the biomass fuel, and can catalyze the cracking of the organic components in the biomass in the carbonization processThe method has the advantages that micromolecule gas is formed, the destructive effect of gas removed by macromolecules in the conventional carbonization process on the structure of the biomass fuel can be reduced, the deep removal of catalytic organic components is facilitated, and the energy waste caused by direct decomposition of the biomass fuel which is prepared by the conventional method and enters flue gas due to unburned sintering material layer due to high organic components is avoided.

In a preferable scheme, the mass percentage of the biomass powder in the size fraction of 0.1-1 mm is not less than 80%.

Preferably, the particle size of the iron-selecting tailing slag-silica tailing slag mixed powder meets the mass percentage content of 0-0.01 mm (less than or equal to 0.01 mm) particle size not less than 90%.

Preferably, the pressing process: the molding is assisted by a mold, and the pressure is 300-1000 kg/cm³The time is 0.5-2.5 min, the temperature range of the die is room temperature-150 ℃, and the particle size of the press forming is 3-5 mm. The mold of the invention is a temperature-controllable stainless steel mold.

Preferably, the low-temperature pretreatment process comprises: heating to 200-300 ℃ at a heating rate of 15-25 ℃/min, and preserving heat for 30-60 min. The low temperature pretreatment process is primarily to remove most of the volatiles by low temperature. The biomass fuel is pretreated at a lower temperature to slowly remove most of volatile components, so that the damage of the organic matters directly entering a high-temperature process and violently decomposing to the particle structure of the formed biomass can be effectively reduced, and the subsequent high-temperature carbonization process is facilitated to form the high-quality biomass fuel with compact structure, low volatile components and high heat value.

In a preferred scheme, the high-temperature carbonization treatment process comprises the following steps: heating to 600-800 ℃ at a heating rate of 2-8 ℃/min, and preserving the heat for 15-30 min. The high-temperature carbonization process mainly realizes the carbonization and transformation process of the biomass. On the basis of the low-temperature pretreatment process, in the fine carbonization process of the high-temperature stage, the volatile matter is deeply removed along the cavity remained by devolatilization in the low-temperature stage, so that the structure of the generated carbon material can be ensured not to be damaged. And most of volatile components are removed in the low-temperature pretreatment process, so that the retention time in the high-temperature carbonization process can be effectively shortened, and the energy consumption in the whole carbonization process can be reduced.

Preferably, the protective atmosphere is N in volume ratio₂80-90% of Ar 10-20%, and the total gas flow is 0.05-0.3L/min.

The invention also provides an iron ore sintering biomass fuel which is obtained by the preparation method.

Preferably, the combustion heat value of the iron ore sintering fuel is 26-33 MJ/kg, the volatile component is 0.5-3%, and the specific surface area is 10-25 m²A porosity of 15-25%, and an apparent density of 1.5-2.2 g/cm³。

The invention also provides an application of the iron ore sintering biomass fuel, which is used for iron ore sintering instead of fossil fuel.

In the preferable scheme, 40-70% of fossil fuel is replaced by the fixed carbon content for iron ore sintering.

The invention replaces fossil fuel with fixed carbon content such as prepared iron ore sintering fuel, mixes and granulates the iron ore, fusing agent and return mine, and then distributes the mixture on a sintering trolley for ignition and sintering.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, the biomass is treated by two different carbonization processes, and the biomass fuel is pretreated at a lower temperature so that most of volatile components are slowly removed, so that the damage of the organic matters directly entering a high-temperature process and violently decomposed to the particle structure of the formed biomass can be effectively reduced; when entering the fine carbonization process of the high-temperature stage, the volatile components are deeply removed along the residual holes in the devolatilization at the low-temperature stage, so that the high-quality biomass fuel with compact structure, low volatile components and high heat value is prepared; most of volatile components are removed in the low-temperature pretreatment process, so that the retention time of the high-temperature carbonization process can be effectively shortened, and the energy consumption of the whole carbonization process can be reduced.

(2) The invention is rich in SiO in the preparation process of the biomass fuel₂The inert fine SiO is fully dispersed in the biomass fuel₂On one hand, the particles occupy the active sites of the biomass fuel, reduce the thermochemical reaction activity,SiO having Si-O tetrahedral structure₂And a stable network structure can be formed with the C-C chain, so that the difference of the reactivity of the biomass fuel and the fossil fuel is further reduced.

(3) The iron oxide component in the tailing slag can catalyze the organic component in the biomass to be cracked into micromolecular gas in the carbonization process, so that the damage effect of the gas removed by macromolecules in the conventional carbonization process on the structure of the biomass fuel is reduced, the deep removal of the catalytic organic component is facilitated, the high organic component of the biomass fuel prepared by the conventional method is avoided, the biomass fuel is unburned in a sintering material layer and is directly decomposed to enter smoke gas to cause energy waste, and valuable iron oxide finally enters sintering ore in the sintering process and is recovered in the subsequent smelting process.

According to the invention, the waste biomass and the tailing slag are used as raw materials, the high-quality biomass fuel with smaller quality and performance difference with the conventional fossil fuel is prepared by regulating and controlling the preparation process, and 40-70% of fossil fuel is successfully replaced by the biomass fuel for iron ore sintering while the synergistic resource utilization of the two types of solid wastes is realized, so that the SOx, NOx and CO in sintering flue gas are effectively reduced₂The discharge of the sintering furnace has important significance for sintering clean production.

Detailed Description

In order to facilitate an understanding of the present invention, the present invention will be described more fully and in detail with reference to the preferred embodiments, but the scope of the present invention is not limited to the specific embodiments described below.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specified, the reagents and materials used in the present invention are commercially available products or products obtained by a known method.