CN108384579B

CN108384579B - Additive for co-production of biomass gasification and direct reduced iron and application thereof

Info

Publication number: CN108384579B
Application number: CN201810269309.9A
Authority: CN
Inventors: 魏汝飞; 龙红明; 李家新; 王平; 孟庆民; 春铁军; 狄瞻霞; 余正伟; 李宁; 王凯祥
Original assignee: Anhui University of Technology AHUT
Current assignee: Anhui University of Technology AHUT
Priority date: 2017-03-13
Filing date: 2017-03-13
Publication date: 2020-07-03
Anticipated expiration: 2037-03-13
Also published as: CN108374065B; CN108384579A; CN106833745A; CN106833745B; CN108374065A

Abstract

The invention discloses an additive for co-production of biomass gasification and direct reduced iron and application thereof, belonging to the technical field of iron making. The additive of the invention comprises sodium carbonate, laterite-nickel ore, dolomite and plant ash. Mixing an iron-containing raw material, biomass and an additive to obtain an iron-containing briquette, putting the iron-containing briquette into a high-temperature container for heating, gasifying the biomass to generate combustible gas, and reducing iron oxide to generate direct reduced iron; the iron-containing raw material comprises iron ore concentrate, blast furnace ash and sintered return ores. The additive reduces the thermal stability of the biomass and the decomposition products thereof, the biomass is used as a reducing agent of iron oxide and a C source and an H source of combustible gas, the iron oxide is used as an iron source for preparing steel and an oxygen source for generating CO through carbon reaction, the catalytic cracking of tar and other decomposition products of the biomass is promoted, the gasification yield of the biomass is improved, and the metallization rate of direct reduced iron is improved.

Description

Additive for co-production of biomass gasification and direct reduced iron and application thereof

The patent application of the invention is a divisional application with an application number of 2017101469513, and the application date of the original application is as follows: 2016-03-13, named as: a method for co-producing biomass gasification and direct reduced iron and an additive used by the method.

Technical Field

The invention relates to the technical field of iron making, in particular to a method for co-producing biomass gasification and direct reduced iron and an additive used by the method.

Background

Biomass energy (bioglass energy) is the form of energy that solar energy stores in biomass in the form of chemical energy, i.e. energy that is carried by biomass. It is derived directly or indirectly from photosynthesis of green plants, and is a renewable energy source. The biomass energy has the advantages of reproducibility, low pollution, wide distribution and the like. The biomass energy is reasonably utilized, the dependence on mineral energy can be effectively reduced, and the pollution to the environment caused by energy consumption is reduced. The development and utilization of biomass energy have become the focus of international attention nowadays, and biomass energy technology has a rather broad development prospect. In the application process of the existing biomass, the biomass is usually gasified, and the biomass gasification is a process of carrying out pyrolysis, oxidation and reduction reforming reactions on high polymers of the biomass under certain thermodynamic conditions by virtue of the action of an air part (or oxygen) and steam, and finally converting the high polymers into combustible gases such as carbon monoxide, hydrogen, low molecular hydrocarbons and the like.

The iron and steel industry, which refers to the industry producing pig iron, steel, industrial pure iron and ferroalloys, is one of the fundamental industries of all industrialized countries of the world. Meanwhile, the steel industry is also a resource and energy intensive industry and a typical high material consumption, high energy consumption and high pollution industry, a large amount of limited resources such as iron ore, coal, water and the like are consumed in the production process, and a large amount of waste is discharged at the same time, so that the environment is seriously polluted. The energy consumption of steel enterprises in China occupies about 10% of the total national energy consumption, and the discharge amounts of waste water, solid waste and waste gas respectively account for 14%, 17% and 16% of the total national industrial pollutant discharge amount. At present, the development of the steel industry in China faces double restrictions of energy and environment, and the energy and the environment become important problems influencing the survival and the development of the steel industry. The method has the advantages that the energy-saving and emission-reducing policies of the steel industry are promoted, the energy-saving and emission-reducing force is increased, the energy utilization efficiency is improved, and the sustainable development of the steel industry can be promoted only by developing low-carbon economy based on low energy consumption and low pollution. Thus, biomass can be used in the steel industry to replace coal and coke from traditional iron making processes.

After searching, the related technical personnel have carried out the research in this aspect, such as: relevant research was conducted at Qingdao university of Juglans and applied for the patent: a direct reduction iron-making device and method based on biomass (patent application No. 201110408416.3, application date: 2011-12-09) and a direct reduction iron-making device and method based on biomass pyrolysis tar (patent application No. 201310107214.4, application date 2013-03-29) adopt the biomass pyrolysis tar to replace coal and natural gas for direct reduction iron-making, thereby reducing the dependence of an iron-making process on fossil energy, improving the quality of a direct reduced iron product and reducing the harm to the environment. However, the method often uses biomass as a substitute of fuel, but the biomass is cracked incompletely in the process of reducing ore and the biomass is cracked, so that a large amount of tar is produced, which not only wastes biomass energy, but also causes serious environmental pollution, and the problem needs to be solved urgently.

Disclosure of Invention

1. Technical problem to be solved by the invention

The invention aims to overcome the defects of higher tar yield and lower gasification yield in the prior art, and provides a method for co-producing biomass gasification and direct reduced iron and an additive used by the method;

according to the biomass gasification and direct reduced iron co-production method, the biomass in the iron-containing briquette is gasified to generate combustible gas, and the iron oxide is reduced to generate direct reduced iron, so that the tar content can be reduced, and the gasification yield can be improved; the metallization rate can be further improved;

the additive for co-production of biomass gasification and direct reduced iron provided by the invention can promote decomposition of macromolecular organic matters, reduce tar content and improve gasification yield through the cooperation of all components; further, the metallization rate can be improved.

2. Technical scheme

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention relates to a biomass gasification and direct reduced iron co-production method, which comprises the steps of mixing and agglomerating an iron-containing raw material, biomass, an additive and a binder to obtain an iron-containing briquette, putting the iron-containing briquette into a high-temperature container for heating, gasifying the biomass to generate combustible gas, and reducing iron oxide to generate direct reduced iron, wherein the additive comprises sodium carbonate, laterite-nickel ore, dolomite and plant ash.

Preferably, the specific steps are as follows:

(1) mixing an iron-containing raw material, biomass, an additive and a binder, and performing hot pressing at 80-120 ℃ by using a briquetting machine to prepare an iron-containing briquette;

(2) and (3) placing the dried iron-containing briquette into a high-temperature container at 800-900 ℃, keeping for 5-10min, then heating to 1150-1250 ℃, and preserving heat for 30-60 min.

Preferably, the iron-containing raw material, the biomass, the additive and the binder are composed of the following components in parts by mass:

preferably, the sodium carbonate, laterite-nickel ore, dolomite and plant ash particles have a 200 mesh throughput rate of greater than 90%.

Preferably, the additive comprises the following components in percentage by mass: sodium carbonate: 20 percent, laterite-nickel ore: 45%, dolomite: 30%, plant ash: 5 percent.

Preferably, said iron-containing raw material therein comprises iron ore concentrate, blast furnace ash and sintered return ores.

Preferably, the biomass has a particle size of less than 40 mesh.

Preferably, the iron concentrate consists of haryand, umber powder, canadian fines, hakuri powder and gibbera powder.

The additive for co-production of biomass gasification and direct reduced iron comprises sodium carbonate, laterite-nickel ore, dolomite and plant ash.

Preferably, the additive also comprises chromium slag.

3. Advantageous effects

Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:

(1) according to the biomass gasification and direct reduced iron co-production method, the biomass in the iron-containing briquette is gasified to generate combustible gas, and the iron oxide is reduced to generate direct reduced iron, so that the tar content can be reduced, and the gasification yield can be improved; the metallization rate can be further improved;

(2) according to the biomass gasification and direct reduced iron CO-production method, biomass is used as a reducing agent of iron oxide and a C source and an H source of combustible gas, the iron oxide is used as an iron source for steel preparation and an oxygen source for CO generation through carbon reaction, and the metallization rate of direct reduced iron is improved; on the other hand, the catalytic cracking of tar and other decomposition products of biomass is promoted;

(3) according to the biomass gasification and direct reduced iron co-production method, the complex oxide strengthens the ion migration effect of pyrolysis products such as tar at high temperature, the electronic cloud in tar is damaged to lose stability, the tar is cracked to generate small molecular organic matters, the combustible gas generated by cracking strengthens the reduction process of iron oxide on the iron oxide, and the metallization rate of the direct reduced iron obtained by reaction is improved;

(3) according to the additive for co-production of biomass gasification and direct reduced iron, metal ions are adsorbed on the surfaces of biomass and decomposition products thereof in the high-temperature heating process, so that the angle deviation of C-C and C-O bonds, the length of the bonds, irregular deformation of carbon rings and the like are promoted, the bond energy is reduced, the thermal stability of tar and other decomposition products of the biomass is reduced, the decomposition of macromolecular organic matters can be promoted, the tar content is reduced, and the gasification yield is improved.

Detailed Description

The following detailed description of exemplary embodiments of the invention, while these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the invention. The following more detailed description of the embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the invention, to set forth the best mode of carrying out the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the invention is to be limited only by the following claims.

Example 1

The invention relates to a biomass gasification and direct reduced iron co-production method, which comprises the following specific steps:

s1: mixing an iron-containing raw material, biomass, an additive and a binder, carrying out hot pressing at 80-120 ℃ by a briquetting machine to prepare an iron-containing briquette, wherein the pressure of the iron-containing briquette is 20MPa, and then keeping the briquette at 105 +/-5 ℃ for 3h until the briquette is completely dried; the iron-containing raw material, the biomass, the additive and the binder are composed of the following components in parts by mass: 50-60 parts of biomass, preferably 52 g; 100-200g, preferably 150g, of the iron-containing material; 5-10g of additive, preferably 8 g; 3-5g of binder, preferably 4 g. The iron-containing raw material comprises blast furnace ash, sintered return ores and iron ore concentrate, and the iron-containing raw material comprises the following components in percentage by mass: blast furnace ash: 5%, sintering return ores: 10% and iron ore concentrate: 85 percent. It is worth mentioning that the binder is bentonite.

It is worth mentioning that: the biomass source comprises straw, wood and other lignocellulose, agricultural product processing leftovers, agricultural and forestry waste and industrial biomass waste in the agricultural and forestry production process except for grain fruits; but also the livestock manure and waste in the animal husbandry production process. The biomass needs to be dried and crushed before use, the drying temperature is 105 ℃, the biomass needs to be crushed until the granularity is less than 40 meshes during crushing, and the ash content of the biomass is required to be less than 3%.

The sintering return ores are as follows: for fine-grained return ores in the sintering process, blast furnace gasThe ash composition is: the blast furnace gas ash is the raw material dust carried by blast furnace gas, contains potassium and sodium elements, K₂The mass percentage of O is as follows: 1.0-2.0%; na (Na)₂The mass percentage of O is as follows: 5.0 to 9.0 percent.

S2: and (2) putting the dried iron-containing briquette into a sealed high-temperature container at 900 ℃ under 800-. Biomass is gasified to produce H₂、CO、CH₄Reducing iron oxide into direct reduced iron by combustible gas;

the additive comprises sodium carbonate, laterite-nickel ore, dolomite and plant ash, and the mass percent of each component is as follows: sodium carbonate: 20 percent, laterite-nickel ore: 45%, dolomite: 30%, plant ash: 5 percent. It is worth further elucidating that: the 200-mesh passing rate of the laterite-nickel ore, dolomite and plant ash particles is more than 90 percent.

The laterite-nickel ore comprises the following chemical components in percentage by mass: ni: 1.8%, TFe: 24% of SiO₂：35％，CaO：1.3％，MgO：16％，Al₂O₃: 3.5%, Cr: 0.5% and the balance impurities.

The dolomite comprises the following chemical components in percentage by mass: TFe: 0.28% of SiO₂：0.66％，Al₂O₃: 0.31%, CaO: 52.12%, MgO: 31.03 percent. The metallization rate, gas yield and tar yield of the prepared direct reduced iron are shown in table 1; not only greatly improves the biomass gasification yield, but also improves the metallization rate of the direct reduced iron.

Comparative example 1

The basic contents of this comparative example are the same as example 1, except that: wherein, no additive is added, and the metallization rate of the directly reduced iron after the reaction, the biomass gasification yield and the tar yield are detected. The results of the experiments are reported in table 1.

Comparative example 2

The basic contents of this comparative example are the same as example 1, except that: the iron-containing raw material does not contain sintered return ores, namely the iron-containing raw material only consists of iron ore concentrate and blast furnace ash, and the metallization rate of directly reduced iron after reaction, the biomass gasification yield and the tar yield are detected. The results of the experiments are reported in table 1.

Comparative example 3

The basic contents of this comparative example are the same as example 1, except that: the iron-containing raw material does not contain laterite nickel ore, namely the iron-containing raw material only consists of iron ore concentrate and sintered return ores, and the metallization rate of directly reduced iron after reaction, the biomass gasification yield and the tar yield are detected. The results of the experiments are reported in table 1.

Comparative example 4

The basic contents of this comparative example are the same as example 1, except that: the dried iron-containing block mass is put into a reactor to be gradually heated from room temperature to 900 ℃, and then heated to 1150-1250 ℃ at the heating rate of 2-3 ℃/min, and the temperature is kept for 30-60 min. And detecting the metallization rate of the directly reduced iron after the reaction, the biomass gasification yield and the tar yield. The results of the experiments are reported in table 1.

TABLE 1 Experimental data

	Metallization rate	Gasification yield	Tar yield
				Example 1	85.8％	93.5％	6.1％
Comparative example 1	83.3％	89.2％	10.1％
				Comparative example 2	78.9％	81.8％	16.8％
Comparative example 3	82.4％	89.0％	10.5％
				Comparative example 4	79.8％	85.9％	12.5％
Example 2	86.3％	92.5％	7.2％
				Example 3	85.9％	93.8％	7.7％
Example 4	84.8％	93.1％	6.2％
				Example 5	85.7％	92.3％	7.1％

Comparing the above conclusions, the following conclusions can be drawn:

(1) from comparison of comparative example 1 and example 1, it was found that under the same conditions, when no additive was added, the gasification yield was low and the tar yield was high, the additive contained a large amount of metal ions;

(2) the comparison between the comparative example 2 and the example 1 shows that under the same conditions, when no sintered return ores are added, the conversion rate and the gasification efficiency of the tar are reduced, and the reason is that the sintered return ores contain partial complex oxides, the complex oxides can generate iron-nickel-magnesium oxides or complex oxides with metal elements of additives under the high-temperature heating condition, the oxides can react with metal ions, the ion migration effect of the complex oxides on cracking products such as tar under the high temperature is enhanced, the electron cloud in the tar is damaged and loses stability, the C-C bond and the C-H bond are easy to break, thereby the tar is cracked to generate small molecular organic matters, and the H generated by cracking is easy to break₂、CH₄The reduction process of the iron oxide is strengthened by the combustible gas to the iron oxide, and the metallization rate of the directly reduced iron obtained by the reaction is improved.

(3) Compared with the comparative example 3 and the example 1, the gasification efficiency of the biomass is reduced under the same conditions when the blast furnace ash is not added, the reason is not clear, but probably because the blast furnace ash contains a large amount of Na, K, Pb and Zn, the metal ions strengthen the attraction and the excursion of the electrons of macromolecular organic matters on one hand, and on the other hand, the metal ions can be combined with iron oxide or nickel-iron compound under the high temperature condition to improve the catalytic activity of the iron oxide and the nickel-iron compound, thereby improving the catalytic effect; the elements not only promote the decomposition of macromolecular organic matters, but also improve the reactivity of iron oxide and nickel-iron compounds, and promote the reduction of the iron oxide, thereby improving the metallization rate.

(4) Comparative example 4, compared with example 1, shows that under the same raw material proportioning condition, when the tar is slowly heated, the yield of the tar is increased, wherein, a large amount of tar is probably generated in the early stage of slow temperature rise, the tar is volatilized from a container in the generation process, oxides such as iron-nickel-magnesium or complex oxides are not effectively formed in the low-temperature process, and on the other hand, the metal ions are difficult to effectively promote the cracking and reforming of macromolecular organic matters in the tar in the low-temperature process, so that the yield of the tar is increased.

Certainly, in order to realize the resource utilization of biomass in the steel industry and the sustainable development of the steel industry, related technicians are available and technical researches in related aspects are carried out. For example, the name of the invention is: method and apparatus for the combined production of pig iron and high quality synthesis gas, patent application No.: 201180048198.5, the filing date of the patent is: 2011-08-03. According to the method, through the co-production of the iron ore and the gas, although the direct reduced iron is prepared by reducing the iron oxide by using the biomass and the combustible gas is simultaneously produced, the tar removal rate is low and the gasification effect is poor due to the fact that macromolecular organic matters such as the tar and the like cannot be effectively cracked and reformed in the gasification process, and the problem is also a key problem limiting the application of effective biomass resources.

The inventor of the patent finally selects proper components as biomass to react with the iron-containing raw material through long-time and continuous exploration to co-produce combustible gas and direct reduced iron, greatly improves the gasification efficiency of the biomass and the tar removal rate, has outstanding substantive characteristics and remarkable progress, and is even impossible for technicians in the field to select the additive without creative labor and applied to a co-production method for preparing the combustible gas and the direct reduced iron from the iron-containing raw material. The above reaction mechanism is not completely clear and has always plagued the inventors of this patent. In order to understand the reaction theory of this reaction, the applicant has conducted several studies and discussions, and it is considered that the following reasons may be:

in the early 900 ℃ heat preservation process, micropores are formed on the iron-containing lumps,the specific surface area of the agglomerate is increased, a larger reaction interface is provided for the subsequent iron-nickel-magnesium oxides or complex oxides and the promotion of tar cracking, the reaction area of reducing the iron oxide by the biomass cracking gas is increased, on one hand, the gradual reduction of the iron oxide is promoted, and a large amount of H is generated in the biomass gasification and cracking processes₂CO and hydrocarbon, which have higher reducibility, the reducing gas promotes the low-temperature reduction of the iron oxide, and the additive promotes the generation of a low-melting-point solid solution phase, so that the biomass can reduce the iron ore only at a lower temperature, and when the biomass is used as a reducing agent of the iron oxide and a C source and an H source of a combustible gas. Iron oxides serve as an iron source for steel production and as an oxygen source for the reaction of carbon to produce CO. Unlike the conventional method for producing direct reduced iron from biomass, the oxygen of the method comes from the internal circulation of iron-containing briquettes, not from oxygen, thereby increasing the metallization rate of direct reduced iron; on the other hand, the catalytic cracking of tar and other decomposition products of biomass is promoted.

In addition, the blast furnace dust and the additive contain a large amount of basic metal ions, the metal ions are adsorbed on the surfaces of the biomass and the decomposition products thereof in the high-temperature heating process, and the electrons of carbon atoms and oxygen atoms of the biomass and the decomposition products thereof are influenced to different degrees under the high-temperature condition, so that the angular deviation of C-C and C-O bonds, the lengthening of bond length, irregular deformation of carbon rings and the like are promoted, the bond energy is reduced, and the thermal stability of tar and other decomposition products of the biomass is reduced. However, when no additive is added, metal ions are difficult to adsorb on the surface of the biomass cellulose, so that biomass depolymerization reaction is dominant, a series of hydrocarbons containing carbon rings are generated, and the yield of tar is high.

In addition, during the process of reducing iron oxide by heating biomass at the continuously increased temperature, a series of active iron-nickel-magnesium complex oxides are produced, wherein the complex oxides comprise: calcium iron compound, calcium magnesium compound, fayalite, nickel iron oxide and the like, and the surfaces of the substances have higher reactivity and polar activation sites under high temperature, thereby promoting the movement of metal ions, strengthening the cracking products of the metal ions such as tar and the like at high temperatureIon drift effect at temperature; in addition, the condensed ring compounds in the tar contain pi electron systems with electronegativity, pi electron clouds are damaged to lose stability, so that C-C bonds and C-H bonds are easy to break, the cracking activation energy is reduced, oxides or complex oxides such as iron-nickel-magnesium further promote catalytic degradation of macromolecular organic matters such as the tar, the macromolecular organic matters in the tar are subjected to ring-opening cracking reaction and easy to degrade, a series of low-molecular hydrocarbon compounds are generated, the gasification conversion efficiency of biomass is improved, and the yield of the tar is reduced. Wherein, especially the nickel iron oxide reduces the hydrocarbon and CH₄Content of H in the combustible gas₂And the content of CO is obviously increased, and certainly, the iron oxide continuously participates in the reaction process in the process of catalytically decomposing organic matters and is continuously reduced to obtain the directly reduced iron, so that the metallization rate of the directly reduced iron is improved.

Example 2

The basic content of the embodiment is the same as that of the embodiment 1, except that the additive consists of sodium carbonate, laterite-nickel ore, dolomite, plant ash and chromium slag; the weight percentage of each component is as follows: sodium carbonate: 15% of laterite nickel ore: 30% of dolomite: 30%, plant ash: 15%, chromium slag: 10 percent. The chromium slag comprises the following chemical components in percentage by mass: SiO 2₂：28％，Al₂O₃：8％，CaO：30％，MgO：15％，Fe₂O₃：10％，Cr₂O₆: 0.8% and Na₂Cr₂O₇: 1% and the balance impurities. And detecting the metallization rate of the directly reduced iron after the reaction, the biomass gasification yield and the tar yield. The results of the experiments are reported in table 1. On one hand, the chromium slag is effectively reduced under the high reducing condition of biomass gasification to generate chromium oxide with a base valence, the chromium oxide is combined with iron oxide and calcium-magnesium compounds in the agglomerates to promote high-efficiency cracking of macromolecular organic matters in tar, so that small-molecular combustible gas is generated, and the iron oxide is continuously reduced to obtain direct reduced iron in the process of catalytically decomposing the organic matters.

Example 3

The iron ore concentrate consists of haryandi, Tubara powder, Canada fine powder, Harpag powder and golden Babby powder, the components of the ore are shown in Table 2, and the mass percentages of various ore powders are as follows: haryandi: 10%, copara: 20% and Canadian refined flour: 40% and Ha mixed powder: 15%, gold rice pudding powder: 15 percent. The metallization rate of the directly reduced iron after the reaction, the biomass gasification yield and the tar yield were measured, and the experimental results are recorded as shown in table 1.

TABLE 2 mineral powder composition (wt/%)

The metallization ratio of the direct reduced iron is further improved, and through repeated discussion, the inventors thought that: the process is that in the process of heat preservation at 900 ℃, crystal water in iron ore powder is heated and decomposed, and more gaps are generated in the iron-containing agglomerates, so that the gas-solid reaction interface for reducing the iron oxide is enlarged, the gaps increase the catalytic action of the iron oxide and complex compounds thereof on macromolecular organic matters in tar, and H generated by the heated and decomposed crystal water₂O is diffused in the reactor, the steam promotes the cracking/reforming of macromolecules under the catalysis of the iron oxide, thereby improving the conversion efficiency of tar, and in the process, the iron oxide is continuously reduced to obtain direct reduced iron in the process of catalytically decomposing organic matters.

Example 4

The additive comprises sodium carbonate, potassium chloride, laterite-nickel ore, dolomite and plant ash, and the mass percentage of each component is as follows: sodium carbonate: 15%, potassium chloride: 20% of laterite nickel ore: 25%, dolomite: 30%, plant ash: 10 percent. And detecting the metallization rate of the directly reduced iron after the reaction, the biomass gasification yield and the tar yield. The results of the experiments are reported in table 1. The alkali metal ions mainly are alkali metals, so that the further cracking of macromolecular organic matters such as tar is promoted, the small molecule agglomeration in a high-temperature environment is inhibited, the conversion efficiency of the tar is improved, the combination of the iron oxide and the macromolecular organic matters is promoted by the additive, and the iron oxide is continuously reduced in the process of catalytically decomposing the organic matters to obtain the directly reduced iron.

Example 5

The additive consists of sodium carbonate, laterite-nickel ore, dolomite, plant ash, chromium slag and vanadium-titanium magnetite slag, and the mass percent of each component is as follows: sodium carbonate: 15% of laterite nickel ore: 30% of dolomite: 20%, plant ash: 10% and chromium slag: 10% of vanadium-titanium magnetite slag: 15 percent. And detecting the metallization rate of the directly reduced iron after the reaction, the biomass gasification yield and the tar yield. The results of the experiments are reported in table 1.

The oxides of iron, vanadium and iron, nickel are generated in the heating process, the oxides of iron, vanadium and iron, nickel promote the cracking of tar in biomass on the basis of promoting the electronic migration of macromolecular organic matters in tar by metal ions and reducing the decomposition activity, and the oxides of iron, vanadium and iron, nickel are continuously reduced and directly reduced iron is obtained in the process of catalytically decomposing the organic matters, so that the metallization rate is improved.

The invention has been described in detail hereinabove with reference to specific exemplary embodiments thereof. It will, however, be understood that various modifications and changes may be made without departing from the scope of the invention as defined in the appended claims. The detailed description is to be construed as illustrative only and not restrictive, and any such modifications and variations are intended to be included within the scope of the invention as described herein. Furthermore, the background is intended to be illustrative of the state of the art as developed and the meaning of the present technology and is not intended to limit the scope of the invention or the application and field of application of the invention.

More specifically, although exemplary embodiments of the invention have been described herein, the invention is not limited to these embodiments, but includes any and all embodiments modified, omitted, combined (e.g., between various embodiments), adapted and/or substituted as would be recognized by those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly based the language employed in the claims and not limited to examples described in the foregoing detailed description or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present invention, the term "preferably" is not exclusive, and it means "preferably, but not limited to" herein. Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. The scope of the invention should, therefore, be determined only by the appended claims and their legal equivalents, rather than by the descriptions and examples given above.

Claims

1. An additive for biomass gasification and direct reduced iron co-production is characterized in that: comprises sodium carbonate, laterite-nickel ore, dolomite, plant ash and chromium slag; the weight percentage of each component is as follows: sodium carbonate: 15% of laterite nickel ore: 30% of dolomite: 30%, plant ash: 15%, chromium slag: 10 percent; the laterite-nickel ore comprises the following chemical components in percentage by mass: ni: 1.8%, TFe: 24% of SiO₂：35%，CaO：1.3%，MgO：16%，Al₂O₃: 3.5%, Cr: 0.5% and the balance impurities.

2. The use of the additive of claim 1 in the co-production of direct reduced iron by biomass gasification, characterized in that: mixing an iron-containing raw material, biomass and an additive to obtain an iron-containing briquette, putting the iron-containing briquette into a high-temperature container for heating, gasifying the biomass to generate combustible gas, and reducing iron oxide to generate direct reduced iron; the iron-containing raw material comprises iron ore concentrate, blast furnace ash and sintered return ores.

3. The use of the additive according to claim 2 in the co-production of direct reduced iron by biomass gasification, characterized in that: the iron ore concentrate consists of Haryandi, Tubara powder, Canadian fine powder, Harpagne powder and golden Babby powder.

4. Use of the additive according to claim 3 for the co-production of direct reduced iron by biomass gasification, characterized in that: putting the iron-containing agglomerate into a high-temperature container at 800-900 ℃, keeping for 5-10min, then heating to 1150-1250 ℃, and preserving heat for 30-60 min.