阅读说明：本技术 一种双窑双基冶金方法 (Double-kiln double-base metallurgy method ) 是由 陶立群 唐竹胜 唐佳 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种双窑双基冶金方法,包括a)在隔焰式回转窑中对含金属氧化物的矿物进行初还原,和b)在内燃式回转窑中进行再还原,以及c)对再还原物进行分离；隔焰式回转窑落料口和内燃式回转窑进料口密封连接,隔焰式回转窑控制温度900-1000℃,内燃式回转窑控制温度1100-1350℃；隔焰式回转窑采用空气喷吹颗粒还原剂,内燃式回转窑采用氧气喷吹固定碳粉末。本发明采用隔焰式回转窑和内燃式回转窑相结合的还原冶金方式,精确控制物料混合和还原温度,可有效避免隔焰式回转窑结圈现象,比传统单一回转窑还原法减少能耗30％,CO<Sub>2</Sub>排放量减少40-50％、而且没有氮氧化物排放。(The invention discloses a double-kiln double-base metallurgical method, which comprises a) carrying out primary reduction on minerals containing metal oxides in a muffle type rotary kiln, b) carrying out re-reduction in an internal combustion type rotary kiln, and c) separating re-reduced matters; the blanking port of the muffle type rotary kiln is hermetically connected with the feeding port of the internal combustion type rotary kiln, the temperature of the muffle type rotary kiln is controlled to be 900-; the flame-isolating rotary kiln adopts air to blow particle reducing agent, and the internal combustion rotary kiln adopts oxygen to blow fixed carbon powder. The invention adopts a reduction metallurgy mode combining the muffle type rotary kiln and the internal combustion type rotary kiln, accurately controls the material mixing and reduction temperature, can effectively avoid the ring formation phenomenon of the muffle type rotary kiln, reduces the energy consumption by 30 percent compared with the traditional single rotary kiln reduction method, and reduces the CO content by 30 percent 2 The emission is reduced by 40-50%, and no nitrogen oxide is emitted.)

1. A double-kiln double-base metallurgical method is characterized by comprising

a) Carrying out a preliminary reduction of the metal oxide containing minerals in a muffle type rotary kiln, and

b) carrying out a re-reduction in an internal combustion rotary kiln, an

c) Separating the re-reduced matter;

the material dropping port of the flame-proof rotary kiln is hermetically connected with the material inlet of the internal combustion rotary kiln, the temperature of the flame-proof rotary kiln is controlled to be 900-;

the granular reducing agent is adopted, the air injection is adopted for the muffle type rotary kiln, and the speed regulation screw machine is adopted for the internal combustion type rotary kiln for closed addition from the feeding hole of the internal combustion type rotary kiln.

2. The double-kiln double-base metallurgical method as claimed in claim 1, wherein the muffle type rotary kiln and the internal combustion type rotary kiln are both horizontal, the bottom surface of the muffle type rotary kiln is higher than the top surface of the internal combustion type rotary kiln, the muffle type rotary kiln is horizontally arranged, the internal combustion type rotary kiln is horizontally inclined by 2.5-5 degrees, and the feed port end is higher than the discharge port end; the length of the muffle type rotary kiln is 30-40m, and the length of the internal combustion type rotary kiln is 8-16 m.

3. The double-kiln double-base metallurgical method as claimed in claim 2, wherein the muffle-type rotary kiln comprises a heat-insulating outer wall and a heat-resistant cylinder, and a reducing agent spray gun is arranged at the tail end and is positioned at the axial center of the muffle-type rotary kiln, and the end part of the reducing agent spray gun extends into the heat-resistant cylinder; the end of the internal combustion rotary kiln is provided with an injection burner, the injection burner extends into a hearth of the internal combustion rotary kiln, and the top of the internal combustion rotary kiln is provided with a burner.

4. The dual-kiln dual-base metallurgical method of claim 1, wherein the particulate reductant is any one of long bituminous coal, lignite or biomass particles, the particulate reductant has a volatile content of 25-40%, fixed carbon of 45% or more, ash of 15% or less, S of 0.5% or less, a thermal stability temperature of 680 ℃ or more, an ash melting point of 1200 ℃ or more, a water content of 8-12 wt%, and a particle size of 5-20 mm.

5. The dual-kiln dual-base metallurgical process of claim 1, wherein the mineral is any one of refractory iron ore, iron ore concentrate or iron-containing solid waste containing nickel oxide and manganese oxide.

6. The dual-kiln dual-base metallurgical process according to any one of claims 1 to 5, characterized by the specific operating steps of:

1) mineral ball pressing treatment: grinding the minerals to 160-mesh and 200-mesh, and pressing the minerals into microspheres with the granularity phi of 20mm multiplied by 15 by a high-strength ball press;

2) pretreatment of a reducing agent: processing the granular reducing agent and the fixed carbon powder according to the required standard, sprinkling water on the granular reducing agent, and standing for more than one day and night for later use;

3) and (3) heating: heating a muffle type rotary kiln, keeping a heat-resistant cylinder body to rotate, starting an internal combustion type rotary kiln injection burner, injecting fixed carbon powder into the internal combustion type rotary kiln by using oxygen, and combusting to generate raw coke oven gas;

4) primary reduction: after raw coke oven gas is filled in the muffle type rotary kiln, preheating the ore pressed with balls in the step 1), then pumping the ore into a heat-resistant cylinder of the muffle type rotary kiln, adjusting the temperature to be 900-;

5) and (3) re-reduction: feeding the material primarily reduced in the step 4) into a hearth of the internal combustion rotary kiln through a discharge hole of the muffle type rotary kiln, controlling the temperature of the internal combustion rotary kiln to be 1100-1350 ℃, and performing re-reduction and slag-iron separation;

6) separation: separating the material re-reduced in the step 5) to obtain a reduced metal product.

7. The dual-kiln dual-base metallurgical method of claim 6, wherein the fixed carbon powder has a volatile matter content of 25-30%, an ash content of 10% or less, a fixed carbon content of 48% or more, a water content of 8% or less, an ash melting point of 1200 ℃ or more, and a fineness of 120 mesh.

8. The dual-kiln dual-base metallurgical process of claim 6, wherein the amount of particulate reducing agent in the muffle type rotary kiln is 30-32 wt% of minerals, and the amount of air is 20-60Nm³Spraying each ton of mineral continuously under the pressure of 24.5-29.4 kPa; the dosage of the granular reducing agent in the internal combustion rotary kiln is 12-20 wt% of the mineral, the dosage of the blowing and burning fixed carbon powder is 18-22 kg/ton of the mineral, and the dosage of the oxygen is 6.3-7.7Nm³For each ton of mineral, spraying in continuously with a pressure of 15-30 kPa.

9. The double-kiln double-base metallurgical method as claimed in claim 6, wherein the muffle type rotary kiln has a filling factor of 25-50%, a rotation speed of 0.3-0.6r/mim, and an initial reduction time of 2.3-2.8 h; the filling coefficient of the internal combustion rotary kiln is 8-15%, the rotating speed is 0.3-2.5r/min, and the time for re-reduction is 0.3-0.5 h.

10. The dual-kiln dual-base metallurgical process of claim 6, wherein the separation of the re-reduced product is performed by wet magnetic separation or dry magnetic separation.

Technical Field

The invention relates to the field of metallurgy, in particular to a double-kiln double-base metallurgy method.

Background

China is a country with rich lean iron ore resources, low-lean dead ores account for more than 96% of iron ore resources, but more than 10 hundred million tons of rich iron ores are imported from abroad every year, and a large amount of iron grains such as hematite, limonite, specularite, siderite, oolitic hematite, antelope stone iron ore and the like are fine and low-lean hard-separation iron ores at home; refractory composite ores such as ferromanganese ore, laterite-nickel ore, vanadium-titanium magnetite ore and ilmenite, refractory iron-containing solid wastes such as sulfuric acid slag, alumina red mud, copper smelting slag, chromium slag, lead-zinc smelting slag, steel mill fly ash and steel mill sludge, and even dangerous wastes such as hexavalent chromium slag, are not developed and utilized comprehensively by a good method. Causes resource waste, large amount of stacking, pollutes the land, pollutes the environment and even becomes a disaster.

According to the industrial statistical data, the emission of carbon dioxide for smelting direct reduced iron per ton of products is 800kg, and the emission of carbon dioxide for smelting iron in a blast furnace is 1600kg, so that the emission of carbon dioxide for non-blast furnace iron smelting can be reduced by 50%. China is the first major country of world steel capacity, the steel yield in China accounts for 73.8% of the whole Asia in 2018, the global yield is 51.3%, blast furnace iron making is dominant, and the yield of direct reduced iron is less than 1% of the total world yield. The national industrial policy is regulated in clear text for a long time, and vigorous development and construction of non-coke iron-making projects such as direct reduced iron, molten reduced iron and the like are encouraged; encourages the comprehensive utilization and development of iron-containing materials such as various refractory iron ores, raw and composite iron ores, metallurgical solid wastes and the like.

In 2011, Japan Shenhu iron and Steel works adopted a coal-based rotary hearth furnace method, in which iron ore powder is mixed with carbon balls, a thin material layer is distributed, a pilot rotary hearth furnace with a diameter phi of 4.5m is adopted, and iron particles and slag are separated at a reduction temperature of about 1450 ℃. They refer to blast furnace ironmaking as the first generation ironmaking process; direct reduction is referred to as the second generation iron making process, while the process is referred to as the "third generation iron making process" (ITmk 3).

The gas-based reduced iron technology for producing 1 ton of Direct Reduced Iron (DRI) requires about 680Nm³Pure hydrogen of 240Nm³The natural gas of (1). Therefore, at present, the development of gas-based reduced iron in China has the problems of great natural gas resource, bottleneck of gas-based reduction technology, and physical and system obstacles such as policy one-sidedly and intractable concept.

The natural gas resources in China are poor, the natural gas belongs to imported countries, the natural gas is high in price, and the natural gas is not suitable for preparing pure hydrogen by natural gas cracking pressure swing adsorption at present, and the two-step method gas-based shaft furnace reduced iron, namely hydrogen metallurgy, is developed. Therefore, it has been proposed: the coke oven gas is used as a gas source to develop a gas-based shaft furnace reduced iron technology, and the heat value of the coke oven gas reaches 16500kJ/Nm³，H₂The content is more than 60 percent, pure hydrogen is prepared by pressure swing adsorption, the method can be used for producing reduced iron by a gas-based shaft furnace, coke oven gas is unbalanced in distribution and not very sufficient and stable in resources, if a plurality of engineering constructions are put into operation, the problem of coke oven gas shortage can occur immediately, in any case, in order to shrink the blast furnace production inevitably and reduce coking enterprises inevitably along with the shortage of coke oven gas resources and the requirement of green environmental protection, if the cost is huge, a coke oven gas-based reduced iron method is developed and invested, gas shortage can occur in the future, in order to survive, a road for preparing pure hydrogen by cracking natural gas must be removed, the production and operation cost is high, the DRI product price is higher than that, and although the DRI product has good quality, the DRI product cannot be accepted by steel companies certainly. The yield of reduced iron in China is less than 50 million tons, and the reduced iron is only produced by a coal-based tunnel kiln method, so that the problems of low productivity, high cost, heavy pollution and the like exist, and other process technologies and equipment technologies also have many problems.

The coal-based rotary kiln reduced iron method is a representative of the coal-based reduced iron method, and the ring formation of the coal-based rotary kiln caused by the technical problems is a fatal problem which cannot be exceeded. Except for reducing metal rotary kilns such as a reduced iron rotary kiln, a zinc oxide rotary kiln, a RKEF rotary kiln and the like, and even all rotary kilns such as a cement rotary kiln, a lime rotary kiln, a dolomite decomposition rotary kiln, a magnesite decomposition rotary kiln, a ceramsite rotary kiln, a refractory material roasting rotary kiln and the like for treating nonmetal, the ring formation problem almost exists as long as the rotary kilns with the temperature of more than 1000 ℃ are used, and the development of high-temperature rotary kiln technology and equipment is severely restricted.

The traditional rotary kiln reduced iron production device generally refers to an internal combustion rotary kiln, is used for producing DRI by reduction, cannot achieve the consistency of the front temperature and the rear temperature, but has to achieve the consistency of parameters such as rotating speed, inclination and the like, in order to ensure the high reduction rate of the DRI or ensure the complete slag iron separation reduction of refractory iron ores, the process reduction temperature needs to exceed over 1100 ℃ or even be higher, and in addition to the entry of reduced coal powder and iron powder, the ring formation phenomenon can occur in the rotary kiln after a certain time, the smooth production is seriously influenced, and the rotary kiln reduced iron production device is a fatal problem which cannot be overcome.

In order to solve the ring formation problem of the rotary kiln, the reduction temperature is required to be reduced to be lower than 1000 ℃, and the reduction time is prolonged. This is why some rotary kiln production lines can only adopt high-grade lump ore to continue producing reduced iron. However, if refractory iron ore and solid waste containing low melting point are reduced, the phase lattice structure cannot be changed if the reduction temperature is reduced, the requirement of the process on the temperature cannot be met, the product quality is low, and if the reduction process is carried out by adopting high temperature to meet the requirement of the reduction process, the rotary kiln is bound.

Disclosure of Invention

The temperature of the coal-based rotary kiln for producing the DRI with high quality needs to exceed 1100 ℃, the ring formation phenomenon can occur in the rotary kiln at the temperature of over 1000 ℃, and the reduction time can be prolonged at the temperature of below 1000 ℃. The invention provides a double-kiln double-base metallurgical method aiming at the problem.

The technical scheme for solving the technical problems is as follows: a double-kiln double-base metallurgical method, which is characterized by comprising a) carrying out primary reduction on minerals containing metal oxides in a muffle type rotary kiln, b) carrying out re-reduction in an internal combustion type rotary kiln, and c) separating re-reduced matters; the material dropping port of the flame-proof rotary kiln is hermetically connected with the material inlet of the internal combustion rotary kiln, the temperature of the flame-proof rotary kiln is controlled to be 900-; the granular reducing agent is adopted, the air injection is adopted for the muffle type rotary kiln, and the speed regulation screw machine is adopted for the internal combustion type rotary kiln for closed addition from the feeding hole of the internal combustion type rotary kiln.

The flame-isolating rotary kiln and the internal combustion rotary kiln are both horizontal, the bottom surface of the flame-isolating rotary kiln is higher than the top surface of the internal combustion rotary kiln, the internal combustion rotary kiln is horizontally inclined by 2.5-5 degrees, and the feed port end is higher than the discharge port end; the length of the muffle type rotary kiln is 30-40m, and the length of the internal combustion type rotary kiln is 8-16 m.

The flame-proof rotary kiln comprises a heat-insulation outer wall and a heat-resistant cylinder body, wherein the tail end of the flame-proof rotary kiln is provided with a reducing agent spray gun, the reducing agent spray gun is positioned at the axis of the flame-proof rotary kiln, and the end part of the reducing agent spray gun extends into the heat-resistant cylinder body; the end of the internal combustion rotary kiln is provided with an injection burner, the injection burner extends into a hearth of the internal combustion rotary kiln, and the top of the internal combustion rotary kiln is provided with a burner.

The granular reducing agent is any one of long bituminous coal, lignite or biomass granules, the volatile matter of the granular reducing agent is 25-40%, the fixed carbon is more than or equal to 45%, the ash content is less than or equal to 15%, the S is less than or equal to 0.5%, the heat stability temperature is more than or equal to 680 ℃, the ash melting point is more than 1200 ℃, the water content is 8-12 wt%, and the granularity is 5-20 mm.

The mineral is any one of refractory iron ore, iron ore concentrate or iron-containing solid waste containing nickel oxide and manganese oxide.

The metallurgical method comprises the following specific operation steps:

1) mineral ball pressing treatment: grinding the minerals to 160-mesh and 200-mesh, and pressing the minerals into microspheres with the granularity phi of 20mm multiplied by 15 by a high-strength ball press;

2) pretreatment of a reducing agent: processing the granular reducing agent and the fixed carbon powder according to the required standard, sprinkling water on the granular reducing agent, and standing for more than one day and night for later use;

3) and (3) heating: heating a muffle type rotary kiln, keeping a heat-resistant cylinder body to rotate, starting an internal combustion type rotary kiln injection burner, injecting fixed carbon powder into the internal combustion type rotary kiln by using oxygen, and combusting to generate raw coke oven gas;

4) primary reduction: after raw coke oven gas is filled in the muffle type rotary kiln, preheating the ore pressed with balls in the step 1), then pumping the ore into a heat-resistant cylinder of the muffle type rotary kiln, adjusting the temperature to be 900-;

5) and (3) re-reduction: feeding the material primarily reduced in the step 4) into a hearth of the internal combustion rotary kiln through a discharge hole of the muffle type rotary kiln, controlling the temperature of the internal combustion rotary kiln to be 1100-1350 ℃, and performing re-reduction and slag-iron separation;

6) separation: separating the material re-reduced in the step 5) to obtain a reduced metal product.

In the step 3), the volatile matter of the fixed carbon powder is 25-30%, the ash content is less than or equal to 10%, the fixed carbon is more than or equal to 48%, the water content is less than or equal to 8%, the ash melting point is more than or equal to 1200 ℃, and the fineness is 120 meshes.

In step 4), the amount of the particle reducing agent is 30-32 wt% of the mineral, and the amount of the air is 20-60Nm³Per ton of mineral, continuously sprayed with a pressure of 24.5-29.4 kPa. In the temperature rise process, the pyrolysis of the particle reducing agent is roughly divided into three stages: in the first stage, drying and dewatering are carried out at the temperature of 300 ℃; in the second stage, severe pyrolysis occurs at the temperature of 300-600 ℃ to separate out a large amount of coal gas and tar, the tar separation rate at 450 ℃ is the maximum, and H begins to be slowly separated out at the temperature of 400-600 DEG₂(ii) a The third stage, the temperature is 600-1000 ℃, the polycondensation is mainly carried out, the semicoke is changed into coke, the tar precipitation in the stage is very little, and the generated gas mainly comprises CO and H₂And a small amount of CH₄. Wherein, CH is precipitated at 550-700 DEG C₄Peak temperature of (600-). 900 ℃ to separate out H₂The maximum amount is 700-800 ℃ which is the peak temperature with the highest CO precipitation speed. H pyrolyzed by coal at 600-1000 ℃₂Content of 10-15% and CH₄3-5% of CO and 15-20% of CO, the reaction is as follows:

C+O₂＝CO₂-395kJ/mol，

CO₂+C＝2CO-76kJ/mol，

C+H₂O＝CO+H₂+10.94kJ/mol，

2C+O₂＝2CO+252.8kJ/mol。

the reduction reaction temperature of the iron oxide and the CO is from 700 ℃, the reaction temperature is from 900 ℃ to 950 ℃, and the iron oxide and the H react violently₂The reduction temperature is from 600 ℃ and has reached a violent reaction up to 900 ℃ with the temperature being higher. Due to H₂Has a diffusion coefficient (Dh) higher than that of CO and has an adsorption capacity on iron oxide₂3.74DCO), H, even at temperatures below 818 ℃₂The rate of reduction of iron oxide is still higher than that of CO (about 5 times), and CO + H is used₂When the mixed gas reduces the iron oxide, the mixed gas is accompanied by H₂The reduction time is reduced by 2.5-3 times by increasing the concentration.

Advanced iron and steel flow of iron and steel research institute and national key laboratory of materials, huge names and GuoThe Piperi et al teach in the kinetic study of Hydrogen reduction of iron oxide at Low temperature: after the granularity of the iron ore powder is reduced from 107.5 mu m to 2.0 mu m at the same temperature, the powder surface area is greatly increased, so that the powder-gas contact area is increased, and the chemical reaction speed is increased by about 8 times. Therefore, pure H in the reduction temperature process of 900-₂The reduction speed is more than 5 times faster than that of CO, and the reaction time is 2.5-2.8 h. Therefore, in the initial reduction process, the reduction temperature is not higher than 1000 ℃, so that a higher reduction rate can be kept, and the ring formation phenomenon of the rotary kiln can be effectively avoided.

The granular reducing agent is sprayed into the heat-resistant cylinder of the muffle type rotary kiln, the large granules are sprayed farther, the small granules are sprayed closer, the middle granules are sprayed at a middle part and form a 'flame tongue', the coal falls in a broom shape, the reducing agent can be sprayed, the cold reducing agent entering the furnace can be preheated for 1-2 seconds, and the heat-resistant cylinder of the muffle type rotary kiln can be heated. The hot air can also react with H which can not directly perform reduction reaction with the minerals₂CO and CH₄When the combustible gas is subjected to rapid oxygen-deficient combustion, part of CO can be additionally provided₂Is CH₄Reaction to CO and H₂Conditions are provided. Taking iron ore as an example, the primary reduction step can simultaneously generate carbon-based and gas-based double-base reduction, and the reaction mainly comprises the following steps:

Fe₂O₃+3H₂＝2Fe+3H₂O，

Fe₃O₄+4H₂＝3Fe+4H₂O，

Fe₂O₃+CO＝2Fe+3CO₂，

Fe₂O₃+3C＝2Fe+3CO，

C+H₂O＝CO+H₂，

2CH₄+O₂＝2CO+4H₂，

CO₂+C＝2CO。

in addition, water in the reducing agent reacts with methane to produce hydrogen gas under a high-temperature atmosphere: CH (CH)₄+H₂O＝CO+3H₂Supplying a reducing gasAnd (3) a body.

In step 5), the amount of the granular reducing agent is 12-20 wt% of the mineral, the amount of the blown and burned fixed carbon powder is 18-22 kg/ton of the mineral, and the amount of the oxygen is 6.3-7.7Nm³And spraying each ton of mineral continuously at the pressure of 15-30kPa, raising the temperature to 1100-1350 ℃, and completing the deep reduction and slag-iron separation after the reaction time is 0.3-0.5 hour. High-temperature flue gas in the furnace is introduced into the muffle type rotary kiln by the induced draft fan to provide sensible heat of 900 ℃ and 1000 ℃ for the muffle type rotary kiln, and the muffle type rotary kiln is rich in H₂And the heat of the raw gas and the reduction gas source of the muffle type rotary kiln are directly increased, the heat of the raw gas is enough for the primary reduction of the muffle type rotary kiln, and a heating system of the muffle type rotary kiln becomes a heat regulating system. The method of the invention enables the muffle type rotary kiln to become a constant temperature heat preservation kiln.

Wherein the filling coefficient of the muffle type rotary kiln is 25-50%, the rotating speed is 0.3-0.6r/mim, the filling coefficient of the internal combustion type rotary kiln is 8-15%, and the rotating speed is 0.3-2.5 r/min; and wet magnetic separation or dry magnetic separation is adopted for separating the re-reduced matters.

FIG. 2 is H₂Equilibrium diagram of reduction of iron oxide with CO, H at 818 deg.C₂Has the same reducing power as CO. When the temperature is less than or equal to 818 ℃, the affinity of CO and O is greater than that of H₂Affinity to O, reducing power of CO than H₂The reduction capability of the catalyst is high; when the temperature is more than or equal to 818 ℃, H₂And O has a greater affinity than CO and O, H₂Has a reduction power greater than that of CO. H₂As a reducing agent, due to H₂The molecule (A) is directly very small, is the most active reducing agent, has the reduction potential which is 11 times that of CO and the reduction permeation speed which is about 5 times that of CO, and can easily permeate into the mineral. Therefore, in the primary reduction process, the gas-based reduction is carried out by H₂Reduction mode with CO, and H during the re-reduction₂The dominant effect of the reduction is better and obvious, so the reduction degree of the re-reduction process is high and the time consumption is short.

The activity of long bituminous coal and biomass particles in the coal-based reducing agent is the best, the activity of lignite is the second, and the activity of anthracite and coke powder is poor. When bituminous coal is pyrolyzed, H is separated out at the temperature of 600-₂The maximum amount;700 ℃ and 800 ℃ are the peak temperature with the highest CO precipitation speed; the reduction kiln of coal-based reduced iron generally passes through a preheating section and then a high-temperature reduction section, and when the temperature of iron oxide is about 570 ℃, decomposition reaction begins to occur, namely Fe is converted₂O₃-Fe₃O₄The FeO-Fe undergoes a sequential decomposition reaction, and when the temperature reaches 900 ℃ or higher, which is the temperature at which the reduction proceeds, the reducing agent has H₂And the CO precipitation is close to the end, the carbon thermal reaction can not be continued, and the reaction can only be carried out at the temperature of more than 950 ℃, and belongs to the typical coal-based carbon thermal reduction reaction.

The existing gas-based reduction modes of Midrex, HYL, Finmet and the like with pure hydrogen as a reducing agent are two-step reduction methods. Namely, the gas sources such as natural gas and the like are separated by means of metal nickel catalytic cracking, Pressure Swing Adsorption (PSA) and the like at a high temperature of more than 900 ℃ to obtain pure hydrogen, and then the pure hydrogen is cooled and conveyed (liquid hydrogen or normal temperature pipeline conveying) to reach the use site, and then the pure hydrogen is heated to 800-. Therefore, the method is only suitable for the areas with abundant natural gas resources at present.

The success of foreign gas-based reduction shaft furnaces is numerous, which indicates that gas-based reduction or hydrometallurgy is successful, but the price of natural gas adopted by the foreign gas-based reduction shaft furnaces is very low. Coal, especially long bituminous coal, biomass particles and lignite can also be pyrolyzed to separate out H₂C, CO in a specific environment of a high-temperature reducing atmosphere₂、O₂、H₂、H₂O can cross-react with each other, see the following chemical reaction equation.

(1) The reduction reaction equation in the high-temperature solid material in the kiln:

Fe₂O₃+CO＝2Fe+3CO₂，

Fe₂O₃+3C＝2Fe+3CO，

2Fe₂O₃+3C＝4Fe+3CO₂，

Fe₂O₃+3H2＝2Fe+3H₂O，

Fe₃O₄+4H₂＝3Fe+4H₂O，

C+H₂O＝CO+H₂，

2CH₄+O₂＝2CO+4H₂。

(2) the reaction equation between the reducing atmosphere outside the high-temperature material in the kiln is as follows:

H₂O+CO＝CO₂+H₂，

2CH₄+O₂＝2CO+4H₂，

CH₄＝C+2H₂，

CO₂+H₂＝CO+H₂O，

C+CO₂＝2CO。

from the above reaction equation, H₂The catalyst has great advantages as a reducing agent; the coal-based reducing agent also has H₂Production, but in the past practical application, the application effect is poor, but the reduction temperature of the whole body of the reduction kiln is stabilized between 900-plus-1000 ℃ (the temperature is lower than 880 ℃, the reduction reaction of iron oxide is not violent; ring formation may occur when the temperature exceeds 1000 ℃), the maximum range is between 880-plus-980 ℃, the oxidized pellets or the iron oxide ore is continuously fed into the kiln, and simultaneously the reducing agent is uniformly distributed in the whole cylinder body range, namely the iron oxide ore (oxidized pellets) and the reducing agent are simultaneously, uniformly and completely distributed at any point of the material in the high-temperature reduction region, so that new reducing agent is introduced at any place of the material in the high-temperature region of the kiln at any moment, if so, the high-temperature reduction region of the whole body, the iron oxide ore (or oxidized pellets) and the reduction coal are all located between 900-plus-1000 ℃ temperature regions at any moment, namely, the temperature section of the violent reaction of iron oxide and the violent reaction of reduced coal, the tar is violently volatilized and H is cracked₂And in the temperature section of CO, the ferric oxide in the material layer can be in time pyrolyzed and gasified with the coal to obtain C, CO and O₂、H₂Direct and indirect cross reduction reactions are formed among gas-gas, solid-solid and gas-solid continuously, a combined type reduction mode combining gas-based indirect reduction and coal-based direct reduction is formed, and the phenomenon that the kiln is provided with a preheating section to causeGasification of coal by low-temperature pyrolysis to produce large amount of CO and H₂The temperature range of the iron oxide reaction is not matched and is not harmonious, so that the iron oxide can fully do useless work (volatilize away from the reduced material and can not contact with the reduced material any more), and the iron oxide can only be recovered as heating energy and can not be used as a gas-based reducing agent with high quality of the iron oxide. This is also the main reason why the conventional coal-based direct reduction method has not applied the good gas-based indirect reduction gas.

If the coal can be uniformly distributed in the whole body of the high-temperature reduction section between the temperature zones of 900-1000 ℃, and simultaneously, high-temperature water gas (H) can be completely input in the temperature zone above 600 ℃ theoretically₂O), can be made H₂Conversion of O to H₂(H₂O+CO＝CO₂+H₂) To increase H₂The concentration of (2) is also favorable for accelerating the reduction rate.

In a word, C, O, H three elements are taken as cores in the high-temperature reducing agent, and full, deep and quick reduction reaction is carried out, so that coal is taken as the reducing agent, and coal-based direct reduction and gas-based indirect reduction are carried out simultaneously, and the simultaneous existence of carbon metallurgy and hydrogen metallurgy is realized, rather than the mismatched, incompatible and insufficient reducing atmospheres which are respectively existed and respectively operated. The invention organically combines the two, optimizes and integrates the two to form a new reduction metallurgy theory, namely a double-kiln double-base reduction metallurgy theory that C, H, O three-element gas-base reduction metallurgy and coal-base reduction metallurgy are in the same place, which is called as a 'ternary double-base reduction metallurgy theory' for short.

The invention adopts a reduction metallurgy mode combining a muffle type rotary kiln and an internal combustion type rotary kiln, takes the metallurgy theory as guidance, accurately controls the material mixing and reduction temperature, and can effectively avoid the ring formation phenomenon of the muffle type rotary kiln, wherein the muffle type rotary kiln provides high-temperature pre-reduced materials with 900-950 ℃ and 75-85% reduction rate for the internal combustion type rotary kiln, the internal combustion type rotary kiln provides high-temperature reduction flue gas for the muffle type rotary kiln, thereby not only overcoming the weak points and obstacles of poor conduction and radiation capability of the muffle type rotary kiln, but also fully utilizing the reduced materials and heat, fully utilizing the thermodynamics and dynamics principles, and fully utilizing the thermodynamics and dynamics principles when the reduction metallurgy mode is adopted, the method can effectively avoidThe double-base reducing atmosphere with both carbon base and gas base is realized in both rotary kilns, and high-quality metallurgical products can be obtained in a short time. Compared with the traditional single rotary kiln reduction method, the method reduces the energy consumption by 30 percent and CO₂The emission is reduced by 40-50%, and no nitrogen oxide is emitted.

Drawings

FIG. 1 is a schematic diagram of an apparatus for use with the present invention, wherein the components are:

1. the heat-insulation wall comprises a heat-insulation outer wall, 2, a heat-resistant cylinder, 3, a reducing agent spray gun, 4, a speed-regulating screw machine, 5, a blowing burner, 6 and a burner.

FIG. 2 is H₂Equilibrium diagram for reduction of iron oxide with CO.

Detailed Description

The present invention is described below with reference to examples, which are provided for illustration only and are not intended to limit the scope of the present invention.

The method adopts a mode of connecting the muffle type rotary kiln and the internal combustion type rotary kiln for metallurgy, a blanking port of the muffle type rotary kiln is hermetically connected with a feeding port of the internal combustion type rotary kiln, the muffle type rotary kiln and the internal combustion type rotary kiln are both horizontal, the bottom surface of the muffle type rotary kiln is higher than the top surface of the internal combustion type rotary kiln, the internal combustion type rotary kiln is horizontally inclined by 2.5-5 degrees, and the feeding port end is higher than the discharging port end; the flame-proof rotary kiln comprises a heat-insulating outer wall 1 and a heat-resisting cylinder 2, the tail end of the flame-proof rotary kiln is provided with a reducing agent spray gun 3, the reducing agent spray gun 3 is positioned at the axis of the flame-proof rotary kiln, and the end part of the reducing agent spray gun extends into the heat-resisting cylinder 2; the end part of the internal combustion rotary kiln is provided with an injection burner 5, the injection burner 5 extends into the hearth of the internal combustion rotary kiln, and the top of the internal combustion rotary kiln is provided with a burner 6; the length of the muffle type rotary kiln is 30-40m, and the length of the internal combustion type rotary kiln is 8-16 m. The granular reducing agent is adopted, the air injection is adopted for the muffle type rotary kiln, and the speed regulation screw machine 4 is adopted for the internal combustion type rotary kiln for adding from the feeding hole of the internal combustion type rotary kiln.

Specifically, the invention adopts patent 201910635371X, a two-section rotary kiln method non-coke iron-making device, as equipment used in the embodiment of the application.