CN115216572B

CN115216572B - Method and system for directly reducing iron oxide and application thereof

Info

Publication number: CN115216572B
Application number: CN202210013549.9A
Authority: CN
Inventors: 叶恒棣; 胡兵; 魏进超; 郑富强; 刘臣; 储太山; 王兆才; 师本敬
Original assignee: Zhongye Changtian International Engineering Co Ltd
Current assignee: Zhongye Changtian International Engineering Co Ltd
Priority date: 2022-01-06
Filing date: 2022-01-06
Publication date: 2023-10-27
Anticipated expiration: 2042-01-06
Also published as: CN115216572A; WO2023130750A1

Abstract

The invention provides a method and a reducing system for directly reducing iron oxide, wherein a pre-reduction device is adopted to carry out the deep reduction of a pre-reduction-deep reduction device, so that Fe which is easy to occur in the process of reducing the iron oxide into metallic iron is reduced ₂ O ₃ →Fe ₃ O ₄ →Fe _x The reduction reaction of the O stage is completed in a pre-reduction device, the pre-reduction product reaching a certain reduction degree and residual coal are hot packed together into a deep reduction device, and Fe occurs in the deep reduction device _x Deep reduction reaction of O-Fe stage. The technology completes the reaction of the iron oxide in the easy reduction stage from trivalent to divalent in the pre-reduction device, completes the reaction of the ferrous iron in the difficult reduction stage to metallic iron in the deep reduction device, fully utilizes the reduction conditions available in the pre-reduction device and the deep reduction device and the characteristics of the reduction process of the iron oxide, and realizes the high efficiency of the reduction process of the iron oxide.

Description

Method and system for directly reducing iron oxide and application thereof

Technical Field

The invention relates to reduction of iron oxide, in particular to a direct reduction method and a reduction system of iron oxide and application of the reduction system, and belongs to the technical field of iron-making production.

Background

The process for extracting metallic iron from iron-bearing minerals (mainly iron oxides) mainly includes blast furnace method, direct reduction method, smelting reduction method, etc. From a metallurgical point of view, iron-making is the reverse of the rusting and progressive mineralization of iron, simply by the reduction of pure iron from iron-containing compounds. A production process for reducing iron ore with a reducing agent at high temperature to obtain pig iron. Iron-making is mainly made of iron ore and coke; the purpose of the coke is to provide heat and produce the reductant carbon monoxide.

Blast furnace smelting is a continuous production process for reducing iron ore to pig iron. The solid raw materials such as iron ore, coke, flux and the like are fed into a blast furnace in batches by a top charging device according to a specified proportioning ratio, and the throat level is kept at a certain height. The coke and ore form alternating layered structures within the furnace. The blast furnace method is adopted for iron making, and has the technical problems of long production period, low production efficiency, large energy consumption, large pollutant production amount and the like.

Direct Reduced Iron (DRI) is an ideal raw material for scrap steel supplements and for smelting high quality specialty steels in short-process steelmaking processes. In recent years, the worldwide production of direct reduced iron has rapidly progressed. Because of the lack of iron ore resources and natural gas, the development of the direct reduction process in China is slow, research and practice hot spots are also focused on the coal-based direct reduction process, and non-coking coal is adopted to produce direct reduced iron or metallic iron. In the existing coal-based direct reduction process, oxidized pellets or cold bonded pellets are generally used as raw materials to react in a rotary kiln to produce DRI. In the direct reduction process of the coal-based rotary kiln, the time from charging to discharging of the furnace burden is 6-8 hours, the production period is longer, and the production efficiency is low. The productivity of the rotary kiln direct reduction process, i.e. how much product is produced by the rotary kiln per unit time, is generally related to the size and structure of the kiln, the raw material and fuel conditions, the temperature and temperature distribution in the kiln, the atmosphere and the charge amount, etc., and the reduction rate of pellets is a fundamental factor affecting the direct reduction production cycle and production efficiency.

At present, the time required from furnace charge entering to product exiting in the direct reduction process of the coal-based rotary kiln can be as long as 8 hours, the production period is longer, and the production efficiency is low. The low pellet reduction speed and long heat preservation reduction time in the rotary kiln are root causes of low production efficiency and long production period of the coal-based rotary kiln direct reduction process. In order to improve the reduction speed of direct reduction, researchers and practitioners put forward some technical measures in the aspects of kiln body design (CN 110229939A, a two-section rotary kiln non-coke iron-making device), pellet batching (CN 106591572A, a method for preparing and reducing reinforced iron ore internally-matched carbon pellets) and the like, but the practicability of industrial application is poor, and most of the methods still stay in an experimental stage at present and have not been popularized and applied yet.

The reducing agent in the direct reduction process of the coal-based rotary kiln is anthracite, and the reduction process mainly involves brief reduction reaction of iron oxide and gasification reaction of coal, namely:

Fe _x O _y +yC＝xFe+yCO (1)

Fe _x O _y +yCO＝xFe+yCO ₂ (2)

C+CO ₂ ＝2CO (3)

the reaction activation energy of the formula (1) is 140-400kJ/mol, the reaction activation energy of the formula (2) is 60-80kJ/mol, and the reaction activation energy of the formula (3) is 170-200kJ/mol. In fact, reaction formula (1) proceeds very well with respect to reaction formulae (2) and (3) Slow, negligible. At present, researchers mostly consider that CO is generated between solid carbon and iron oxide through Boolean reaction (formula (3)), namely, the solid carbon mainly reacts CO ₂ Reduction to CO generally occurs rarely directly with iron oxide. The reduction reaction is carried out from the outside of the pellets to the pellets, and the gasification speed of carbon and the diffusion speed of gas in the pellets have great influence on the reduction reaction. In the reduction process, the reduction reaction of the pellets is controlled by interfacial chemical reaction and internal diffusion mixing. As the reduction reaction proceeds, the chemical reaction resistance is decreasing and the internal diffusion resistance is increasing. Therefore, the reducing gas in the middle and later stages of reduction is difficult to enter the pellet cores, the reduction degree is gradually increased, and the method is an important reason for influencing the overall reduction speed.

Disclosure of Invention

Aiming at the problems of slow diffusion speed of reducing gas in the middle and later stages of reduction in the existing coal-based rotary kiln direct reduction process, slow pellet reduction speed, long heat preservation reduction time of pellets in a kiln body, the invention provides a method and a reduction system for directly reducing iron oxides, and application thereof, wherein a pre-reduction device is adopted to carry out deep reduction of a pre-reduction-deep reduction device, so that iron oxides are reduced into Fe which is easy to occur in the process of metal iron ₂ O ₃ →Fe ₃ O ₄ →FeO→Fe _x The reduction reaction of the O stage is completed in a pre-reduction device, the pre-reduction product reaching a certain reduction degree and residual coal are hot packed together into a deep reduction device, and Fe occurs in the deep reduction device _x Deep reduction reaction of O-Fe stage. The technology of the invention completes the reaction of the iron oxide in the easy reduction stage from trivalent to divalent in a pre-reduction device, and obtains partial iron crystals in the pre-reduction device; and then, the reaction of most ferrous iron to metallic iron in the difficult-to-reduce stage is completed in a deep reduction device, the reduction conditions available in the pre-reduction device and the deep reduction device are fully utilized, and the characteristics of the iron oxide reduction process are combined, so that the high efficiency of the iron oxide reduction process is realized.

According to a first embodiment of the present invention, a method for direct reduction of iron oxides is provided.

The method for directly reducing the iron oxide comprises the steps of pre-reducing the iron oxide through a pre-reduction device to obtain a pre-reduction product; and then carrying out deep reduction on the pre-reduction product by a deep reduction device to obtain molten iron.

In the invention, in the deep reduction device, the pre-reduction product reacts with carbon to obtain molten iron and high-temperature gas. The high-temperature gas is conveyed into a pre-reduction device to be used as a combustion heat source and a reducing gas, and the high-temperature gas and iron oxide are subjected to reduction reaction in the pre-reduction device.

Preferably, the high-temperature gas is conveyed to the pre-reduction device after the gas reforming process.

In the present invention, the reaction of iron oxide in the pre-reduction unit is:

xFe ₂ O _3(s) +(3x-2)CO _(g) ＝2Fe _x O _(s) +(3x-2)CO _2(g) ，

xFe ₂ O _3(s) +(3x-2)H _2(g) ＝2Fe _x O _(s) +(3x-2)H ₂ O _(g) ，

Fe ₂ O _3(s) +3CO _(g) ＝2Fe _(s) +3CO _2(g) ，

Fe ₂ O _3(s) +3H _2(g) ＝2Fe _(s) +3H ₂ O _(g) 。

preferably, the degree of reduction of the iron oxide in the pre-reduction unit is controlled to be η, η is 40 to 80%, preferably 50 to 70%, more preferably 60 to 65%; wherein:x∈[2/3，+∞)。

preferably, the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity.

Preferably, the iron oxide is controlled to be reduced by a pre-reduction device to obtain pre-reductionThe conductivity of the product was 1 x 10 ⁵ -1*10 ⁷ Ω ^-1 ·m ^-1 Preferably 3 x 10 ⁵ -7*10 ⁶ Ω ^-1 ·m ^-1 More preferably 5 x 10 ⁵ -5*1*10 ⁶ Ω ^-1 ·m ^-1 。

Preferably, the reduction degree of the iron oxide in the pre-reduction device is controlled by controlling one or more of the carbon distribution amount in the iron oxide, the thermal insulation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device. The reduction degree of the iron oxide in the pre-reduction device is proportional to the carbon distribution amount in the iron oxide, the thermal insulation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device.

Preferably, the amount of carbon incorporated in the iron oxide is controlled to be 10 to 40wt%, preferably 15 to 30wt%, more preferably 20 to 25wt%; further preferably 20-25%; for example 20%,21%,22%,23%,24%,25%. The carbon blending amount is the weight ratio of the coal carbon in the iron oxide entering the pre-reduction device to the whole iron oxide.

Preferably, the thermal insulation reduction time of the iron oxide in the pre-reduction device is controlled to be 60-180min, preferably 70-140min, more preferably 90-120min; for example: 80min,90min,100min,110min,120min. The thermal insulation reduction time of the iron oxide in the pre-reduction device refers to the time that the iron oxide stays in the highest temperature zone in the pre-reduction device.

Preferably, the reduction temperature in the prereducing device is controlled to be 800-1400 ℃, preferably 850-1300 ℃, more preferably 900-1200 ℃. For example: 900 ℃,1000 ℃,1050 ℃,1100 ℃,1150 ℃,1200 ℃,1300 ℃,1400 ℃. The reduction temperature in the pre-reduction device refers to the highest temperature zone in the pre-reduction device.

Preferably, the real-time conductivity sigma of the material in the prereducing device is detected in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method specifically comprises the following steps:

establishing a relation between the conductivity and the state of the materials in the pre-reduction device and the reduction degree of the materials:

if sigma _{Time of day} ≤0.1Ω ^-1 ·m ^-1 Indicating that the main Fe of the materials in the pre-reduction device ₂ O ₃ In the pre-reduction unit, the real-time reduction degree of the iron oxide in the pre-reduction unit is [0,1 ]]；

If 0.1 < sigma _{Time of day} ≤1000Ω ^-1 ·m ^-1 Indicating that the main Fe of the materials in the pre-reduction device ₃ O ₄ In the pre-reduction unit, the real-time reduction degree of the iron oxide in the pre-reduction unit is (1, 11.1 percent)]；

If 1000 < sigma _{Time of day} ≤1*10 ⁵ Ω ^-1 ·m ^-1 Indicating that the material in the pre-reduction device exists in the form of main FeO, and the real-time reduction degree of the iron oxide in the pre-reduction device is (11.1 percent, 33.3 percent)]；

If 1 x 10 ⁵ ＜σ _{Time of day} ≤1*10 ⁷ Ω ^-1 ·m ^-1 Indicating that the materials in the pre-reduction device mainly exist in the forms of FeO and Fe, and the real-time reduction degree of the iron oxide in the pre-reduction device is (33.3 percent, 80 percent)]；

If sigma _{Time of day} ＞1*10 ⁷ Ω ^-1 ·m ^-1 Indicating that the main Fe form exists in the material in the pre-reduction device, and the real-time reduction degree of the iron oxide in the pre-reduction device is (80 percent, 1)]。

Preferably, the real-time reduction degree eta of the iron oxide in the pre-reduction device is based on _{Real world} Adjusting the technological conditions of reduction of the iron oxide in the pre-reduction device; the method comprises the following steps:

if eta _{Real world} = (1 +/-10%) eta, keeping the carbon distribution amount in the existing iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device to continue to operate;

If eta _{Real world} > (1+10%) η mediated by any one or more of the following means: reducing the carbon distribution amount in the iron oxide, reducing the reduction temperature in the pre-reduction device, shortening the thermal insulation reduction time of the iron oxide in the pre-reduction device, and controlling the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η；

If eta _{Real world} < (1-10%) η mediated by any one or more of the following means: improving the carbon distribution amount in the iron oxide, increasing the reduction temperature in the pre-reduction device, prolonging the thermal insulation reduction time of the iron oxide in the pre-reduction device, and controlling the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the present invention, the pre-reduction device is a rotary kiln, rotary hearth furnace, tunnel kiln, fluidized bed or shaft furnace. Preferably, the prereducing device is a rotary kiln.

In the present invention, the deep reduction device is a smelting reduction furnace, a converter, an electric furnace, or a blast furnace.

In the invention, the reduction of the reduction temperature in the pre-reduction device is achieved by the following means: the coal injection amount in the rotary kiln is reduced and/or the secondary air inlet amount of the rotary kiln is reduced.

In the present invention, the raising of the reduction temperature in the pre-reduction device is achieved by: increasing the coal injection amount in the rotary kiln and/or increasing the secondary air inlet amount of the rotary kiln.

In the invention, the shortening of the thermal insulation reduction time of the iron oxide in the pre-reduction device is realized by increasing the rotating speed of the rotary kiln.

In the invention, the prolonging of the thermal insulation reduction time of the iron oxide in the pre-reduction device is realized by reducing the rotating speed of the rotary kiln.

Preferably, the carbon distribution amount in the iron oxide is reduced specifically as follows: each decrease in the amount of carbon incorporation Δm=10% m ₁ Wherein m is ₁ The original carbon distribution amount in the iron oxide is calculated; i.e. if eta _{Real world} > (1+10%) eta, controlling carbon distribution quantity m of next batch of iron oxide _i ＝m _i-1 Syndrome of deficiency m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the carbon distribution quantity delta m in the iron oxide of the next batch is reduced again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

Preferably, the carbon distribution amount in the iron oxide is specifically increased by: each increment delta m of carbon compounding amount ₀ ＝10％m ₁ Wherein m is ₁ The original carbon distribution amount in the iron oxide is calculated; i.e. if eta _{Real world} < (1+10%) eta, controlling carbon distribution quantity m in next batch of iron oxide _i ＝m _i-1 A + [ delta ] m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the carbon distribution quantity delta m in the iron oxide of the next batch is increased again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

Preferably, the reducing the coal injection amount in the rotary kiln specifically includes: each reduction of the coal injection amount Δp=10% p ₁ Wherein p is ₁ The original coal injection amount in the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling coal injection quantity p in the rotary kiln _j ＝p _j-1 - Δp; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the coal injection quantity delta p is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Preferably, the increasing of the coal injection amount in the rotary kiln specifically includes: each increment Δp=10%p of coal injection amount ₁ Wherein p is ₁ The original coal injection amount in the rotary kiln; i.e. if eta _{Real world} < (1+10%) eta, and the coal injection quantity p in the rotary kiln _j ＝p _j-1 A + [ delta ] p; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the coal injection quantity delta p is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Preferably, the reducing the secondary air inlet of the rotary kiln specifically comprises: each reduction of secondary air intake Δf=10% f ₁ Wherein f ₁ The primary secondary air intake of the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling secondary air quantity f of rotary kiln _k ＝f _k-1 - Δf; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the secondary air inlet quantity delta f is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Preferably, the increasing the secondary air inlet of the rotary kiln specifically comprises: each increment Δf=10% f of the secondary air intake ₁ Wherein f ₁ The primary secondary air intake of the rotary kiln; i.e. if eta _{Real world} And (1+10%) eta, controlling secondary air quantity f of rotary kiln _k ＝f _k-1 A + [ delta ] f; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the secondary air inlet quantity delta f is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Preferably, the increasing the rotation speed of the rotary kiln specifically includes: each increment Δs=10%s of rotation speed ₁ Wherein s is ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 A + [ delta ] s; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the rotating speed delta s is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Preferably, the rotating speed of the rotary kiln is reduced specifically as follows: each decrease in rotational speed Δs=10%s ₁ Wherein s is ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 - Δs; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the rotating speed delta s is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

In the invention, the high-temperature gas is conveyed to the pre-reduction device after the gas reforming process, specifically: the pre-reduction product obtained by pre-reduction in the pre-reduction device enters a reforming shaft, the material flows downwards in the reforming shaft from top to bottom, and is discharged from the bottom of the reforming shaft to enter a deep reduction device; the high-temperature gas generated in the deep reduction device enters from the lower part or the bottom of the reforming vertical shaft, contacts with the pre-reduction product in the deep reduction device, and generates a Budder reaction and a water gas reaction to realize reforming, and the reformed high-temperature gas is conveyed into the pre-reduction device to be used as reducing gas.

Preferably, the high-temperature gas generated in the deep reduction device is conveyed to the reforming shaft after dust removal.

Preferably, the temperature of the high temperature gas exiting the deep reduction device is greater than 1400 ℃, preferably greater than 1500 ℃, more preferably greater than 1600 ℃. For example: 1400 ℃,1450 ℃,1500 ℃,1550 ℃,1600 ℃,1650 ℃,1700 ℃,1800 ℃.

Preferably, the content of CO in the reformed high-temperature gas obtained after passing through the reforming shaft is higher than 30vol%, preferably higher than 35vol%.

Preferably, H in the reformed high-temperature gas obtained after passing through the reforming shaft ₂ The content of (C) is higher than 2vol%, preferably H ₂ The content of (C) is higher than 3vol%, more preferably H ₂ The content of (2) is higher than 5vol%.

According to a second embodiment provided by the present invention, there is provided an iron oxide direct reduction system.

An iron oxide direct reduction system or a system for use in the method described in the first embodiment, the system comprising a pre-reduction device and a deep reduction device. Wherein, the discharge gate of pre-reduction device communicates with the feed inlet of degree of depth reduction device, and the gas outlet of degree of depth reduction device communicates to pre-reduction device's air inlet.

Preferably, the system further comprises a reforming shaft. The reforming vertical shaft comprises a feed inlet, a discharge outlet, an air inlet and an air outlet. The discharge port of the pre-reduction device is communicated with the feed port of the reforming vertical shaft. The discharge port of the reforming vertical shaft is communicated with the feed port of the deep reduction device. The gas outlet of the deep reduction device is communicated with the gas inlet of the reforming vertical shaft. The air outlet of the reforming vertical shaft is communicated with the air inlet of the pre-reduction device.

Preferably, the pre-reduction device is a rotary kiln, rotary hearth furnace, tunnel kiln, fluidized bed or shaft furnace. Preferably, the prereducing device is a rotary kiln.

Preferably, the deep reduction device is a smelting reduction furnace, a converter, an electric furnace, or a blast furnace.

Preferably, the rotary kiln comprises a drying section, a preheating section, a reduction roasting section and a slow cooling section. The air outlet of the reforming vertical shaft is communicated with the reduction roasting section and/or the preheating section of the rotary kiln.

Preferably, the rotary kiln further comprises a kiln body air duct mechanism, an annular rotary sliding rail and a rotary sliding mechanism. The annular rotary slide rail is sleeved outside the rotary kiln and is supported by the support. The wheel end of the rotary sliding mechanism is connected with the annular rotary sliding rail, the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism, and the inner end of the kiln body air duct mechanism is connected with the kiln wall. Namely, the rotary kiln and the kiln body air duct mechanism can simultaneously rotate on the annular rotary slide rail through the rotary sliding mechanism.

Preferably, a plurality of annular rotary slide rails are arranged outside the rotary kiln. Any one annular rotary slide rail is connected with the rotary kiln through a plurality of rotary sliding mechanisms and a plurality of kiln body air duct mechanisms.

Preferably, the kiln body air duct mechanism comprises an air inlet connecting piece, a stop valve, a pull rod and an air inlet. An air inlet channel is formed in the kiln body of the rotary kiln. One end of the stop valve extends into the air inlet channel, and the other end of the stop valve is communicated with the air inlet connecting piece. The air inlet is arranged on the air inlet connecting piece. One end of the air inlet connecting piece, which is far away from the rotary kiln, is connected with one end of the pull rod, and the other end of the pull rod is connected with the rotary sliding mechanism.

Preferably, the rotary sliding mechanism comprises a rotary wheel seat, a lateral rotary wheel and a vertical rotary wheel. The rotary wheel seat is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail. And lateral rotating wheels are arranged on the rotating wheel seats positioned on the side surfaces of the annular rotating slide rail. And vertical rotating wheels are arranged on the rotating wheel seats positioned on the outer bottom surface of the annular rotating slide rail. The rotary wheel seat can rotationally slide on the annular rotary slide rail through the lateral rotary wheel and the vertical rotary wheel.

Preferably, the rotary kiln further comprises a horizontal sliding mechanism. The horizontal sliding mechanism comprises a horizontal wheel seat, a horizontal pulley and a horizontal rail. The horizontal track is a groove-shaped track arranged at the upper end of the bracket. The bottom of the horizontal wheel seat is arranged in the horizontal track through a horizontal pulley. The top end of the horizontal wheel seat is connected with the annular rotary slide rail.

Preferably, the system further comprises a slewing mechanism. The slewing mechanism comprises a slewing motor and a large gear ring. The inner ring of the large gear ring is fixed on the outer wall of the rotary kiln, and the outer ring of the large gear ring is meshed and connected with a transmission gear of the rotary motor.

Preferably, the system further comprises conductivity detection means. The conductivity detection device comprises a detection coil and a magnetic core. The detection coil is connected with a magnetic conduction core, and the magnetic conduction core is arranged on the kiln body of the rotary kiln.

Preferably, the magnetically permeable core is disposed in a side wall of the kiln body of the rotary kiln, and the distance between the end of the magnetically permeable core and the inner wall of the rotary kiln is 0.5-20mm, preferably 1-15mm, and more preferably 2-10mm.

According to a third embodiment of the present invention, there is provided the use of a direct reduction system for iron oxides.

Use of the system described in the second embodiment for the direct reduction of iron oxides.

Preferably, the system described in the second embodiment is used for the direct reduction of one or more of hematite, magnetite, limonite, siderite, goethite.

During the reduction of iron oxide, the iron element is gradually reduced from high to low valence. When the temperature is more than 570 ℃, the reduction sequence of the iron oxide is Fe ₂ O ₃ →Fe ₃ O ₄ →FeO→Fe _x O and Fe. Wherein Fe is ₂ O ₃ →Fe ₃ O ₄ →FeO→Fe _x The process of O takes a long time because the crystal structure of the iron oxide needs to be changed many times. And Fe (Fe) _x The process of O-Fe is the process from iron oxide to simple substance iron, the difficulty is the greatest, and the required process condition is higher.

The technology adopts a method of pre-reduction by a pre-reduction device and deep reduction by a deep reduction device to reduce Fe which is easy to occur in the process of reducing iron oxide into metallic iron and takes longer time ₂ O ₃ →Fe ₃ O ₄ →FeO→Fe _x The reduction reaction of the O stage is completed in a pre-reduction device, wherein the reducing agent in the pre-reduction device mainly comprises the added coal-based reducing agent and the top gas of the deep reduction device, and the main effective components are CO and H ₂ Part of the metallic iron is also formed during the pre-reduction stage of the pre-reduction unit. Thus, the following reactions mainly occur within the rotary kiln:

3Fe ₂ O ₃ (s)+CO(g)＝2Fe ₃ O ₄ (s)+CO2(g)。

xFe ₃ O ₄ (s)+(4x-3)CO(g ₎ ＝3Fe _x O(s)+(4x-3)CO ₂ (g)。

Fe _x O(s)+CO(g)＝xFe(s)+CO ₂ (g)。

3Fe ₂ O ₃ (s)+H ₂ (g)＝2Fe ₃ O ₄ (s)+H ₂ O(g)。

xFe ₃ O ₄ (s)+(4x-3)H ₂ (g)＝3Fe _x O(s)+(4x-3)H ₂ O(g)。

Fe _x O(s)+H ₂ (g)＝xFe(s)+H ₂ O(g)。

in the pre-reduction device, fe ₂ O ₃ First reduced to Fe ₃ O ₄ The crystal structure of the iron oxide changes for the first time, and the reduction degree of the iron oxide is improved to 11.1 percent from 0. Then from Fe ₃ O ₄ The crystal structure of the iron oxide is changed for the second time after being reduced into FeO, and the reduction degree of the iron oxide is improved from 11.1 percent to 33.3 percent. Then from FeO to Fe _x The crystal structure of the iron oxide is changed for the third time, and the reduction degree of the iron oxide is improved to about 80 percent from 33.3 percent; in this process, some crystals of elemental iron have appeared, which enter the deep reduction device together with other iron oxides, and which act as "nuclei" to accelerate the reduction of the iron oxides of the other iron oxides in the deep reduction device and the growth of the iron crystals. That is to say the reactions taking place in the prereducing device are: most of Fe ₂ O ₃ Is reduced to FeO, part of Fe ₂ O ₃ Is reduced to Fe; the material reduced to FeO and reduced to Fe constitutes a pre-reduced product reaching a certain degree of reduction.

The pre-reduction product reaching a certain reduction degree and residual coal are hot packed together into a deep reduction device, and Fe occurs in the deep reduction device _x The deep reduction reaction of O-Fe stage, the reducing agent is mainly C dissolved in molten slag iron, and mainly the following reactions occur:

Fe _x O(s)+[C]＝xFe(s)+CO(g)。

in the deep reduction device, the pre-reduction product with a certain reduction degree and carbon are changed into a molten state, and iron oxide in the pre-reduction product with a certain reduction degree takes iron in the pre-reduction product with a certain reduction degree as a core and is further reduced into elemental iron, so that the reduction of the whole iron oxide is realized. Because +2 valent iron is reduced into simple substance iron, the required process conditions are more severe, and the kinetic energy and thermodynamic energy requirements are higher, a deep reduction device is adopted, so that iron oxide and a reducing agent enter liquid (the inside of a pre-reduction device is gas-solid reaction), and the reduction of the iron oxide is accelerated by the liquid reaction.

The invention has the technical characteristics that:

(1) The reduction degree of the two steps of deep reduction of the pre-reduction device and the deep reduction device is controlled, so that the high efficiency of the reduction process of the iron oxide is realized. The reduction process of the pre-reduction device mainly comprises the steps of coal vaporization and gas-solid reduction reaction of iron oxide and carbon monoxide or hydrogen, mass transfer and heat transfer efficiency are lower because of the lower material layer and the gas flow on the material layer, the reduction temperature of the pre-reduction device is generally not higher than 1250 ℃ because of easy ring formation, the reduction reaction in the pre-reduction device is slower, and therefore, long time is required for completely reducing the iron oxide into metallic iron in the pre-reduction device, but only the ferrous stage (including part of elemental iron) is reduced, and the reaction time is greatly shortened. The reduction reaction of the deep reduction device mainly occurs in molten slag iron with the temperature of more than 1400 ℃, and reactants are molten (liquid), so that the reduction reaction occurs at a very high rate. However, the materials in the deep reduction device are required to be melted into a molten state, and the melting temperature of the ferric oxide and the ferric oxide is higher, so that the energy consumption can be greatly increased if the high-valence iron oxide is directly reduced in the deep reduction device.

The technology completes the reaction of the iron oxide in the easy reduction stage from trivalent to divalent in a pre-reduction device, and completes the reaction of the ferrous iron in the difficult reduction stage from ferrous iron to metallic iron in a deep reduction device. The method fully utilizes the reduction conditions available in the pre-reduction device and the deep reduction device and the characteristics of the reduction process of the iron oxide, and realizes the high efficiency of the reduction process of the iron oxide.

(2) Through reasonable cascade utilization of energy, the energy consumption is minimized. The smelting reduction process generates a large amount of high-temperature gas with the temperature of more than 1500 ℃, and the part of the high-temperature gas has a large amount of sensible heat and latent heat.

In order to optimize the reduction process of the iron oxide, if the reduction of the iron oxide is carried out in the pre-reduction device, firstly, the reduction time of the iron oxide is greatly prolonged, secondly, the reduction of the iron oxide is incomplete, and the material is extremely easy to form a ring phenomenon in the pre-reduction device. If the reduction of the iron oxide is carried out in the deep reduction device, the reduction energy consumption of the iron oxide is greatly increased and the reduction efficiency of the iron oxide is reduced due to the higher dissolution temperature of the ferric oxide and the ferroferric oxide. Therefore, the reduction process of the iron oxide is reasonably distributed in the pre-reduction device and the deep reduction device, and the reduction process is very important to the technical problems of reduction efficiency, energy consumption, avoidance of looping phenomenon and the like of the iron oxide.

In the present invention, the degree of reduction of the iron oxide in the pre-reduction apparatus is controlled to be η, η is 40 to 80%, preferably 50 to 70%, more preferably 60 to 65%. That is, in the pre-reduction apparatus, it is most reasonable to control the state where most of the iron trioxide is reduced to ferrous oxide and the state where part of the iron trioxide is reduced to elemental iron. It has been found through experimentation that if all of the iron trioxide is reduced to only a pre-reduction product of ferrous oxide, then the pre-reduction product is subjected to deep reduction in a deep reduction unit. The reduction efficiency of the pre-reduction product in the deep reduction device is still lower, and the energy consumption is still larger. If the pre-reduction product contains part of the simple substance iron, the reduction efficiency of the pre-reduction product in the deep reduction device is greatly improved.

It was found through experimental investigation that the degree of reduction of iron oxide in the pre-reduction apparatus was controlled to be η, η being 40 to 80%, preferably 50 to 70%, more preferably 60 to 65%. The method is a reasonable technical scheme, not only can the whole reduction efficiency of the iron oxide be improved, but also the energy consumption of the reduced elemental iron of the iron oxide can be reduced.

The invention controls the reduction degree of iron oxide in the pre-reduction device based on the following theory:

Iron ore raw materials corresponding to 1 ton of molten iron are generated, and the Fe content wFe in the molten iron MFe and the Fe content in the slag M slag are setThe O content wFeO, 97% of the sum of which is derived from the iron ore raw material, which is hematite (assuming all Fe ₂ O ₃ ) Mass MFe ₂ O ₃ Content wFe ₂ O ₃ ，

1) In the pre-reduction device, when Fe ₂ O ₃ Reduced to Fe only ₃ O ₄ At the time of deoxidation 1/9, the pre-reduction degree is 11.1%, and the consumed carbon amount (energy consumption):

3Fe ₂ O ₃ +CO＝2Fe ₃ O ₄ +CO ₂

C+CO ₂ ＝2CO

obtaining:

in the deep reduction unit, the remaining reduction reaction is carried out, converting into direct reduction of C:

Fe ₃ O ₄ +C＝3FeO+CO

obtaining:

FeO+C＝Fe+CO

obtaining:

2) In the pre-reduction device, when Fe ₂ O ₃ Reduction to Fe ₃ O ₄ When the reaction mixture is reduced to FeO, the deoxidization is 1/3, the pre-reduction degree is 33.3 percent, and the consumed carbon amount (energy consumption) is as follows:

3Fe ₂ O ₃ +CO＝2Fe ₃ O ₄ +CO ₂

C+CO ₂ ＝2CO

obtaining:

Fe ₃ O ₄ +CO＝3FeO+CO ₂

C+CO ₂ ＝2CO

obtaining:

FeO+C＝Fe+CO

obtaining:

3) In the pre-reduction device, when Fe ₂ O ₃ Reduction to Fe ₃ O ₄ FeO, and removing residual 2/3 oxygen when reducing to Fe, setting the pre-reduction degree as eta (more than 33.3%), and consuming carbon (energy consumption):

3Fe ₂ O ₃ +CO＝2Fe ₃ O ₄ +CO ₂

C+CO ₂ ＝2CO

obtaining:

Fe ₃ O ₄ +CO＝3FeO+CO ₂

C+CO ₂ ＝2CO

obtaining:

FeO+CO＝Fe+CO ₂

C+CO ₂ ＝2CO

obtaining:

in the deep reduction unit, the remaining reduction reaction is carried out, converting into direct reduction of C: feo+c=fe+co

Obtaining:

aiming at the technical problems of high energy consumption, longer production period, low production efficiency and the like of adopting a pre-reduction device to reduce iron oxide in a process for treating the iron oxide by adopting a direct reduction method, the invention provides a technical scheme of adopting the pre-reduction device to pre-reduce and adopting a deep reduction device to deeply reduce; preliminary reduction (pre-reduction) of iron oxide is carried out by a pre-reduction device, and Fe which is easy to occur in the process of reducing the iron oxide into metallic iron ₂ O ₃ →Fe ₃ O ₄ →FeO→Fe _x The reduction reaction of the O stage is completed in a pre-reduction device, the reaction period of the process is longer, and firstly, the procedures of drying, preheating and the like are needed for the iron oxide; fe is added to _x The deep reduction reaction of the O-Fe stage is completed in a deep reduction device, and the stage needs a high-temperature environment to realize the high reduction of iron. By the technical scheme of pre-reduction of the pre-reduction device and deep reduction of the deep reduction device, the direct reduction efficiency of the iron oxide is greatly improved, and the energy consumption in the direct reduction process is saved by reasonable process adjustment.

In a preferred scheme of the invention, the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity.

Basic principle of conductivity detection:

in the rotary kiln, the main component of the iron-containing raw material for reduction is Fe ₂ O ₃ 、Fe ₃ O ₄ And in the process of transferring from the kiln tail to the kiln head, the iron oxide is reduced into FeO and Fe step by step under different temperature and atmosphere conditions, and at the moment, the composition change of the iron oxide causes the change of electricity and magnetic conductivity. When the temperature in the kiln exceeds the Curie temperature of the material, the ferromagnetic material is converted into paramagnetic material, namely the relative magnetic permeability is about 1, and the composition change of the material only changes the conductivity of the material, so that the reduction degree of the iron oxide at the detection point, the composition of the material and the temperature can be judged according to the change of the conductivity of the iron-containing raw material in the rotary kiln.

The non-contact temperature measurement and material composition detection device and method based on conductivity can accurately detect the temperature and the material composition without being influenced by complex environments in the container and interfering the characteristics of the material, prevent the problem of looping caused by higher temperature of a material layer, and effectively control the pre-reduction degree or the metallization rate of furnace burden in a pre-reduction-melting reduction process and a direct reduction iron-electric furnace process.

The detection of the conductivity of the material mainly adopts an eddy current detection method, a detection coil is arranged above a test piece of the metal material, an alternating excitation signal is added into the coil, an alternating magnetic field is generated around the coil, a metal conductor arranged in the magnetic field generates eddy currents, the eddy currents also generate magnetic fields, the directions of the eddy currents are opposite, the effective impedance of the electrified coil changes due to the reaction of the magnetic fields, and the change of the impedance of the coil completely and uniquely reflects the eddy current effect of an object to be detected.

The detection environment is kept unchanged, when materials with different conductivities are detected, the influence on the impedance of the detection coil is different due to the different sizes of eddy currents generated by the surface layer, so that the conductivity of the metal material can be measured by measuring the change condition of the impedance of the coil.

Adopting a rotary kiln to perform prereduction, and designing a conductivity detection device:

and the steel plate on the outer wall of the rotary kiln is provided with holes for reducing the interference of the eddy current effect of the steel plate on the impedance of the coil, so that the magnetic field generated by the coil can be transmitted to the surface of the material in the kiln.

The fireproof lining is provided with holes, the lining is not perforated, a certain thickness is reserved for heat insulation, meanwhile, the magnetic cores are embedded for magnetic conduction, the magnetic field reaching the materials is enhanced, the blocking magnetic field generated by eddy current of the materials is conducted, only one magnetic core is used for magnetic conduction, and the attenuation of the magnetic field in an air gap is reduced.

Conductivity detection process:

(1) Conventional rotary kilns are divided into four sections, and Fe generally occurs in a preheating section ₂ O ₃ →Fe ₃ O ₄ FeO, feO→Fe occurs in the firing zone _x O; by inquiring data, fe ₂ O ₃ 、Fe ₃ O ₄ Resistivity ρ and conductivity of FeO and FeThe following are provided:

substance (B)	Resistivity/Ω·m	Conductivity/omega ^-1 ·m ^-1
			Fe ₂ O ₃	10 ²	10 ^-2
Fe ₃ O ₄	10 ^-2	10 ²
			FeO	10 ^-4	10 ⁴
Fe	10 ^-7	10 ⁷

(2) Since the reduction of iron oxide proceeds stepwise, it is considered that the iron oxide composition of the reduced material is single or two, such as Fe ₂ O ₃ With Fe ₃ O ₄ 、Fe ₃ O ₄ Mixing with FeO, feO and Fe, so that two pure iron oxide substances are mixed according to different proportions, measuring sigma of the mixture, and establishing an equation of the content ratio of sigma to iron oxide; then reducing and roasting the known sigma mixture under the conditions of reducing temperature T and reducing time T, detecting chemical composition and sigma of a roasting product, continuously correcting a relation equation, and finally obtaining the following components:

Meanwhile, a relational expression between the material reduction degree delta eta and the conductivity delta sigma, and between the delta sigma and the reduction temperature T and between the material reduction degree delta eta and the conductivity delta sigma and between the material reduction temperature T and the material reduction time T is established:

Δη＝κΔσ＝f(T,t)

(3) In actual production, a material of known chemical composition (i.e. known σ ₁ 、η ₁ ) Entering from the kiln tail of the rotary kiln, drying, preheating and roasting to convert into prereduced materials with unknown chemical composition, wherein the technological conditions are respectively carbon blending quantity M _c Reduction temperature T, reduction time T; a plurality of (3-4 circles of) conductivity detection devices are arranged at the end positions of a preheating section and a roasting section of the rotary kiln, and the conductivity sigma of the pre-reduced material is measured in time ₂ To obtain

Δη＝κΔσ＝κ(σ ₂ -σ ₁ )

η ₂ ＝η ₁ +Δη

(4) When eta ₂ When the value is eta (1+/-10%) of the pre-reduction degree of the furnace burden required by the deep reduction device, the existing process condition is maintained; when eta ₂ When the value exceeds the pre-reduction degree eta (1+10%) of the furnace burden required by the deep reduction device, the reduction temperature T (such as coal injection amount reduction, secondary air amount reduction) should be reduced appropriately in time, and the reduction time T (such as rotational speed acceleration) is reduced; when eta ₂ When the value is lower than the pre-reduction degree eta (1-10%) of the furnace burden required by the deep reduction device, the reduction temperature T (such as increasing the coal injection quantity and injecting the gas fuel through a plurality of injection holes) should be properly increased in time, the reduction time T (such as increasing the rotation speed) and the coal blending quantity M are increased _c 。

Through experimental study, the conductivity of the pre-reduction product obtained by reducing the iron oxide through a pre-reduction device is controlled to be 1 x 10 ⁵ -1*10 ⁷ Ω ^-1 ·m ^-1 Preferably 3 x 10 ⁵ -7*10 ⁶ Ω ^-1 ·m ^-1 More preferably 5 x 10 ⁵ -5*1*10 ⁶ Ω ^-1 ·m ^-1 . And by detecting the conductivity, and then writing the component content of the corresponding substance, the reduction degree of the iron oxide in the pre-reduction device can be calculated.

Conductivity of 1 x 10 ⁵ -1*10 ⁷ Ω ^-1 ·m ^-1 When the reduction degree of the iron oxide is 40-80%.

Conductivity of 3 x 10 ⁵ -7*10 ⁶ Ω ^-1 ·m ^-1 When the reduction degree of the iron oxide is 50-70%.

Conductivity of 5 x 10 ⁵ -5*1*10 ⁶ Ω ^-1 ·m ^-1 When the reduction degree of the iron oxide is 60-65%.

Accordingly, the inventors of the present invention found through experiments that the degree of reduction of the material by reduction can be obtained by detecting the conductivity of the material.

The research shows that the reduction degree of the iron oxide in the pre-reduction device has a direct relation with the carbon distribution amount in the iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device; the reduction degree of the iron oxide in the pre-reduction device is in direct proportion to the carbon distribution amount in the iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device kiln and the reduction temperature in the pre-reduction device.

The experimental study shows that:

In order to control the reduction degree of the iron oxide to be 40-80%, the carbon distribution amount in the iron oxide should be controlled to be 10-40wt%, the heat preservation reduction time of the iron oxide in the pre-reduction device is controlled to be 60-180min, and the reduction temperature in the pre-reduction device is controlled to be 800-1400 ℃.

In order to control the reduction degree of the iron oxide to be 50-60%, the carbon distribution amount in the iron oxide should be controlled to be 15-30wt%, the heat preservation reduction time of the iron oxide in the pre-reduction device is controlled to be 70-140min, and the reduction temperature in the pre-reduction device is controlled to be 850-1300 ℃.

In order to control the reduction degree of the iron oxide to be 60-65%, the carbon distribution amount in the iron oxide should be controlled to be 20-25wt%, the heat preservation reduction time of the iron oxide in the pre-reduction device is controlled to be 90-120min, and the reduction temperature in the pre-reduction device is controlled to be 900-1200 ℃.

Therefore, the reduction degree of the iron oxide in the pre-reduction device can be controlled by controlling the carbon distribution amount in the iron oxide and the reduction process conditions of the iron oxide in the pre-reduction device. And then detecting the reduction degree by detecting the conductivity of the pre-reduction product, and realizing real-time control of the reduction degree by adjusting the carbon distribution amount in the iron oxide and the reduction process conditions of the iron oxide in the pre-reduction device.

In the present invention, the carbon distribution amount in the iron oxide means the weight ratio of the amount of coal in the iron oxide fed into the pre-reduction apparatus to the entire iron oxide. The incubation reduction time of the iron oxide in the pre-reduction device refers to the time during which the iron oxide stays in the highest temperature zone (e.g., 1000-1250 ℃) in the pre-reduction device. The reduction temperature in the pre-reduction unit refers to the highest temperature zone (e.g., 1000-1250 ℃) in the pre-reduction unit.

Fe due to the existence of the following conditions in the reduction process of the iron oxide ₂ O ₃ 、Fe ₃ O ₄ 、FeO、Fe _x O (i.e., feO coexists with Fe) and Fe; analysis by detecting the conductivity of iron oxides of different degrees of reductionThe relation between the conductivity and the state of the materials in the rotary kiln and the reduction degree of the materials can be established by the components of the iron oxide in the pre-reduction product under the reduction degree as follows:

if sigma _{Time of day} ≤0.1Ω ^-1 ·m ^-1 Indicating that the main Fe of the materials in the pre-reduction device ₂ O ₃ In the pre-reduction unit, the real-time reduction degree of the iron oxide in the pre-reduction unit is [0,1 ]]The method comprises the steps of carrying out a first treatment on the surface of the Indicating that iron oxide has not yet begun to be reduced or that there is little portion to be reduced;

if 0.1 < sigma _{Time of day} ≤1000Ω ^-1 ·m ^-1 Indicating that the main Fe of the materials in the pre-reduction device ₃ O ₄ In the pre-reduction unit, the real-time reduction degree of the iron oxide in the pre-reduction unit is (1, 11.1 percent) ]The method comprises the steps of carrying out a first treatment on the surface of the Indicating that the iron oxide starts to be reduced or has been reduced to Fe ₃ O ₄ But has not yet been reduced to FeO.

If 1000 < sigma _{Time of day} ≤1*10 ⁵ Ω ^-1 ·m ^-1 Indicating that the material in the pre-reduction device exists in the form of main FeO, and the real-time reduction degree of the iron oxide in the pre-reduction device is (11.1 percent, 33.3 percent)]The method comprises the steps of carrying out a first treatment on the surface of the Indicating that the iron oxide has been reduced beyond Fe ₃ O ₄ In the state of (2) starts to be reduced or has been reduced to FeO, but has not been reduced to Fe.

If 1 x 10 ⁵ ＜σ _{Time of day} ≤1*10 ⁷ Ω ^-1 ·m ^-1 Indicating that the materials in the pre-reduction device mainly exist in the forms of FeO and Fe, and the real-time reduction degree of the iron oxide in the pre-reduction device is (33.3 percent, 80 percent)]The method comprises the steps of carrying out a first treatment on the surface of the Indicating that iron oxide has been reduced beyond the FeO state and that some has begun to be reduced or has been reduced to Fe, but has not been fully reduced to Fe.

If sigma _{Time of day} ＞1*10 ⁷ Ω ^-1 ·m ^-1 Indicating that the main Fe form exists in the material in the pre-reduction device, and the real-time reduction degree of the iron oxide in the pre-reduction device is (80 percent, 1)]. Indicating that the iron oxide has been reduced to Fe in its entirety.

Through experimental study, the pre-reduction product can be detectedAnd detecting the conductivity and the components of the pre-reduction product to obtain the reduction degree of the iron oxide. According to the process conditions of the invention, under different reducing conditions, the real-time reduction degree eta of the iron oxide in the pre-reduction device is determined _{Real world} The process conditions for reducing the iron oxide in the pre-reduction device are timely adjusted so that the real-time reduction degree eta of the iron oxide in the pre-reduction device is achieved _{Real world} ＝(1±10％)η。

The invention provides a method for detecting, judging and controlling, which specifically comprises the following steps:

if eta _{Real world} = (1 +/-10%) eta, keeping the carbon distribution amount in the existing iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device to continue to operate; that is, the process conditions of the pre-reduction unit currently employed are the conditions under which the present invention is required to obtain the pre-reduced product.

If eta _{Real world} > (1+10%) η mediated by any one or more of the following means: reducing the carbon distribution amount in the iron oxide, reducing the reduction temperature in the pre-reduction device, shortening the thermal insulation reduction time of the iron oxide in the pre-reduction device, and controlling the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} = (1±10%) η; that is, the reduction degree of the pre-reduction product obtained under the process conditions of the pre-reduction device adopted at present exceeds the reduction degree required by the invention, which means that the reduction degree of the iron oxide in the pre-reduction device is excessive, and that the process conditions cause the reduction time of the iron oxide in the pre-reduction device to be too long, thereby reducing the reduction efficiency of the whole iron oxide and possibly causing the generation of a ring formation phenomenon.

If eta _{Real world} < (1-10%) η mediated by any one or more of the following means: improving the carbon distribution amount in the iron oxide, increasing the reduction temperature in the pre-reduction device, prolonging the heat preservation reduction time of the iron oxide in the rotary kiln, and controlling the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} = (1±10%) η. That is, the degree of reduction of the pre-reduced product obtained under the process conditions of the pre-reduction apparatus currently employed does not reach the degree of reduction of the pre-reduced product of the present inventionThe required reduction degree is obviously shown, so that the reduction degree of the iron oxide in the pre-reduction device is low, and the process condition is also shown that the load of the deep reduction device is increased when the pre-reduction product enters the deep reduction device for deep reduction, the energy consumption of the deep reduction device is increased, and the reduction efficiency of the whole iron oxide is reduced.

In the invention, the carbon distribution amount in the iron oxide is specifically reduced as follows: each decrease in the amount of carbon incorporation Δm=10% m ₁ (or 2%m) ₁ 、30％m ₁ 、4％m ₁ 、5％m ₁ 、6％m ₁ 、7％m ₁ 、8％m ₁ 、9％m ₁ 、12％m ₁ 、15％m ₁ 、18％m ₁ 、20％m ₁ 、25％m ₁ 、30％m ₁ 、35％m ₁ 、40％m ₁ 、45％m ₁ 、50％m ₁ Etc.), where m ₁ The original carbon content in the iron oxide is calculated. I.e. if eta _{Real world} > (1+10%) eta, controlling carbon distribution quantity m of next batch of iron oxide _i ＝m _i-1 Syndrome of deficiency m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) η, the carbon number Δm (that is to say m) in the next batch of iron oxide is again reduced _i+1 ＝m _i-1 -2 Δm) until the real-time reduction degree η of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the carbon distribution amount in the iron oxide is specifically improved by: each increment delta m of carbon compounding amount ₀ ＝10％m ₁ (or 2%m) ₁ 、30％m ₁ 、4％m ₁ 、5％m ₁ 、6％m ₁ 、7％m ₁ 、8％m ₁ 、9％m ₁ 、12％m ₁ 、15％m ₁ 、18％m ₁ 、20％m ₁ 、25％m ₁ 、30％m ₁ 、35％m ₁ 、40％m ₁ 、45％m ₁ 、50％m ₁ Etc.), where m ₁ Is ironOriginal carbon dose in oxide; i.e. if eta _{Real world} < (1+10%) eta, controlling carbon distribution quantity m in next batch of iron oxide _i ＝m _i-1 A + [ delta ] m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) η, the carbon distribution Δm (that is, m) in the next batch of iron oxide is increased again _i+1 ＝m _i-1 +2×Δm) to a real-time reduction degree η of iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the coal injection amount in the pre-reduction device is specifically reduced as follows: each reduction of the coal injection amount Δp=10% p ₁ (or 2%p) ₁ 、30％p ₁ 、4％p ₁ 、5％p ₁ 、6％p ₁ 、7％p ₁ 、8％p ₁ 、9％p ₁ 、12％p ₁ 、15％p ₁ 、18％p ₁ 、20％p ₁ 、25％p ₁ 、30％p ₁ 、35％p ₁ 、40％p ₁ 、45％p ₁ 、50％p ₁ Etc.), where p ₁ The original coal injection amount in the pre-reduction device; i.e. if eta _{Real world} > (1+10%) eta, controlling coal injection quantity p in the prereduction equipment _j ＝p _j-1 - Δp; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) η, the coal injection quantity Δp (that is to say p) is again reduced _i+1 ＝p _i-1 -2 Δp) until the real-time reduction degree η of iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the increasing of the coal injection amount in the pre-reduction device is specifically as follows: each increment Δp=10%p of coal injection amount ₁ (or 2%p) ₁ 、30％p ₁ 、4％p ₁ 、5％p ₁ 、6％p ₁ 、7％p ₁ 、8％p ₁ 、9％p ₁ 、12％p ₁ 、15％p ₁ 、18％p ₁ 、20％p ₁ 、25％p ₁ 、30％p ₁ 、35％p ₁ 、40％p ₁ 、45％p ₁ 、50％p ₁ Etc.), where p ₁ The original coal injection amount in the pre-reduction device; i.e. if eta _{Real world} < (1+10%) eta, and the coal injection quantity p in the prereduction device _j ＝p _j-1 A + [ delta ] p; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) η, the coal injection quantity Δp (that is to say p) is increased again _i+1 ＝p _i-1 +2 Δp) to a real-time reduction degree η of iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the method for reducing the secondary air inlet of the pre-reduction device specifically comprises the following steps: each reduction of secondary air intake Δf=10% f ₁ (or 2%f) ₁ 、30％f ₁ 、4％f ₁ 、5％f ₁ 、6％f ₁ 、7％f ₁ 、8％f ₁ 、9％f ₁ 、12％f ₁ 、15％f ₁ 、18％f ₁ 、20％f ₁ 、25％f ₁ 、30％f ₁ 、35％f ₁ 、40％f ₁ 、45％f ₁ 、50％f ₁ Etc.), where f ₁ The primary secondary air inlet quantity of the pre-reduction device; i.e. if eta _{Real world} > (1+10%) eta, controlling secondary air quantity f of prereduction device _k ＝f _k-1 - Δf; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) η, the secondary air intake Δf (that is to say f) is again reduced _i+1 ＝f _i-1 -2 Δf) until the real-time reduction degree η of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the secondary air intake measuring tool for adding the pre-reduction deviceThe body is as follows: each increment Δf=10% f of the secondary air intake ₁ (or 2%f) ₁ 、30％f ₁ 、4％f ₁ 、5％f ₁ 、6％f ₁ 、7％f ₁ 、8％f ₁ 、9％f ₁ 、12％f ₁ 、15％f ₁ 、18％f ₁ 、20％f ₁ 、25％f ₁ 、30％f ₁ 、35％f ₁ 、40％f ₁ 、45％f ₁ 、50％f ₁ Etc.), where f ₁ The primary secondary air inlet quantity of the pre-reduction device; i.e. if eta _{Real world} (1+10%) eta, controlling secondary air quantity f of prereduction device _k ＝f _k-1 A + [ delta ] f; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) η, the secondary air intake Δf (that is, f) is increased again _i+1 ＝f _i-1 +2 Δf) to a real-time reduction degree η of iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the increasing of the rotation speed of the pre-reduction device is specifically as follows: each increment Δs=10%s of rotation speed ₁ (or 2%s) ₁ 、30％s ₁ 、4％s ₁ 、5％s ₁ 、6％s ₁ 、7％s ₁ 、8％s ₁ 、9％s ₁ 、12％s ₁ 、15％s ₁ 、18％s ₁ 、20％s ₁ 、25％s ₁ 、30％s ₁ 、35％s ₁ 、40％s ₁ 、45％s ₁ 、50％s ₁ Etc.), wherein s ₁ The original rotating speed of the pre-reduction device; i.e. if eta _{Real world} > (1+10%) eta, controlling rotation speed s of prereduction device _r ＝s _r-1 A + [ delta ] s; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) η, the rotation speed Δs (that is to say s) is increased again _i+1 ＝s _i-1 +2 Δs) to a real-time reduction degree η of iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

In the invention, the rotating speed of the rotary kiln is reduced specifically as follows: each decrease in rotational speed Δs=10%s ₁ (or 2%s) ₁ 、30％s ₁ 、4％s ₁ 、5％s ₁ 、6％s ₁ 、7％s ₁ 、8％s ₁ 、9％s ₁ 、12％s ₁ 、15％s ₁ 、18％s ₁ 、20％s ₁ 、25％s ₁ 、30％s ₁ 、35％s ₁ 、40％s ₁ 、45％s ₁ 、50％s ₁ Etc.), wherein s ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 - Δs; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) η, the rotation speed Δs (that is to say s) is again reduced _i+1 ＝s _i-1 -2 Δs) until the real-time reduction degree η of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

In a preferred embodiment of the present invention, the reaction between iron oxide and carbon occurs in the deep reduction step of the deep reduction apparatus, and iron, carbon monoxide and part of carbon dioxide are produced, specifically: fe (Fe) _x O(s)+C＝xFe(s)+CO(g)+CO ₂ (g) A. The invention relates to a method for producing a fibre-reinforced plastic composite This reaction step gives high-temperature carbon monoxide and carbon dioxide gas, which are collectively referred to as "high-temperature gas". The high-temperature gas produced in the deep reduction device has a temperature of more than 1400 ℃ and up to more than 1700 ℃ and has a certain pressure. In the technical scheme of the invention, the heat and the heat value of the high-temperature gas are fully utilized, the high-temperature environment is needed in the rotary kiln, meanwhile, the reducing gas is needed, the high-temperature gas generated by the deep reduction device is conveyed into the rotary kiln and serves as a reducing agent, and meanwhile, the heat of the part of gas is fully utilized, so that the maximum utilization of resources is realized.

Top output of deep reduction deviceA large amount of high-temperature gas with the temperature of up to 1500 ℃ contains a large amount of unreacted CO and H ₂ In addition, contains a large amount of CO ₂ And water vapor. The product of the pre-reduction in the coal-based rotary kiln mainly comprises high-temperature pre-reduction raw materials and high-temperature residual coal. The technology carries out countercurrent reaction on the high-temperature pre-reduction product of the pre-reduction device and the high-temperature gas discharged by the deep reduction device, and CO and H in the high-temperature gas ₂ CO and H when passing through the high temperature pre-reduction product layer ₂ Can be subjected to reduction reaction with unreacted iron oxide to promote the further reduction of the pre-returned raw material. CO generated by reduction reaction in deep reduction device ₂ And H ₂ O and CO in high-temperature gas ₂ And H ₂ When O passes through the hot residual coal of the high-temperature pre-reduction product, boolean reaction and water gas reaction occur, so that the reforming of the high-temperature gas is realized.

Preferably, the high-temperature gas generated by the deep reduction device contains a part of carbon dioxide, and the pre-reduction product discharged by the pre-reduction device contains a part of carbon residue and has a high-temperature environment; in the preferred scheme of the invention, a gas reforming process is added, and carbon dioxide in the high-temperature gas can be subjected to Boolean reaction (C+CO) with residual carbon in the pre-reduction product ₂ =2co), generating carbon monoxide; the water in the high temperature gas reacts with the residual carbon in the pre-reduction product to produce water gas (H ₂ O(g)+C(s)＝CO(g)+H ₂ (g) Hydrogen and carbon monoxide. In the process of the gas reforming procedure, the high-temperature gas generated by the deep reduction device utilizes carbon in a pre-reduction product and a high-temperature environment to convert carbon dioxide and water in the high-temperature gas into reducing gases such as carbon monoxide, hydrogen and the like through reaction, so that the content of the reducing gases in the gas conveyed to the pre-reduction device is further improved, the reformed high-temperature gas after the gas reforming is conveyed to the pre-reduction device, and the high-temperature reducing gases enter the pre-reduction procedure in the pre-reduction device and are used for reducing iron oxides. By the technical means, the active ingredients and the product environment in the pre-reduction product and the deep reduction device product are fully utilized, the optimization of the technical scheme is realized, the resources are fully utilized, and the height is further improvedThe content of reducing gas in the warm gas improves the reduction efficiency in the pre-reduction device; the high-temperature gas generated by the deep reduction device is utilized, so that the use amount of fuel in the pre-reduction device is also saved; by adopting the technical scheme of the invention, the carbon distribution amount in the raw materials entering the pre-reduction device can be reduced, and compared with the prior art, the fuel consumption can be saved by 20-30% by adopting the technical scheme of the invention.

According to the invention, the high-temperature gas is reformed through the reforming vertical shaft, so that the pre-reduction product is further reduced. The sensible heat of the pre-reduction product and the sensible heat of the high-temperature gas and the reducing gas in the sensible heat are fully utilized to realize the further pre-reduction of the iron oxide. Part of iron oxide does not complete the reduction reaction process in the pre-reduction process of the pre-reduction device, and CO and H in high-temperature gas are in the gas reforming high-temperature reaction material layer ₂ And (3) continuing to perform further pre-reduction reaction on unreduced iron oxide, improving the reduction degree of raw materials fed into the furnace by the deep reduction device, and reducing the energy consumption of the deep reduction device.

In addition, the high Wen Can coal in the pre-reduction product of the pre-reduction device, CO2 and H2O in high-temperature coal gas and CO generated by reduction of the iron oxide in the material layer are fully utilized ₂ And H ₂ O, generating gas reforming reaction, converting sensible heat of the above materials and gas flow into high-quality reducing gases CO and H ₂ Converting sensible heat into chemical energy of reducing gas, and reforming to obtain a large amount of CO and H ₂ The heat can be provided for the direct reduction reaction of the pre-reduction device through oxidation heat release, and the heat can also be used as a reducing agent for the direct reduction reaction of the pre-reduction device, so that the energy loss caused by cooling of high-temperature coal gas in the transmission process can be reduced, and the reduction gas CO and H in the coal gas fed into the pre-reduction device can also be enhanced ₂ The content of the iron oxide is enhanced, and the iron oxide reduction reaction in the pre-reduction device is enhanced.

In addition, the temperature of the pre-reduction product of the pre-reduction device is about 1200 ℃, the temperature of high-temperature gas generated by the deep reduction device is more than 1500 ℃ and can be up to 1700 ℃ at most, when the pre-reduction product and the high-temperature gas are subjected to the countercurrent reforming reaction, the pre-reduction product of 1200 ℃ moves from the upper part to the lower part, the high-temperature gas moves from the lower part of the material layer to the upper part, the reforming reaction can convert a part of heat into chemical energy, the temperature of the gas can be gradually reduced, but in the process of gradually reducing the pre-reduction product, the temperature of the high-temperature gas is higher as the temperature of the high-temperature gas is higher, the temperature of the pre-reduction product is higher and higher, and the energy consumption of the deep reduction device is reduced when the pre-reduction product is discharged from the head of the pre-reduction device to the deep reduction device.

In the invention, iron oxide is subjected to two-step reduction processes to obtain molten iron, wherein the molten iron is respectively subjected to pre-reduction by a pre-reduction device and deep reduction (smelting reduction) by a deep reduction device; because the reduction of the iron oxide needs to manage the states of a plurality of irons, the invention provides a stage and characteristics of the reduction of the iron oxide, and then the time and energy consumption conditions of the iron oxide in each reduction stage are analyzed by combining the process characteristics of a pre-reduction device and a deep reduction device, the stage which is most suitable for the pre-reduction of the iron oxide in the pre-reduction device is placed in the pre-reduction device for carrying out, and the stage which is suitable for the deep reduction in the deep reduction device is placed in the deep reduction device for carrying out; the reduction degree of the iron oxide in the pre-reduction device is controlled, so that the iron oxide is reasonably distributed in the pre-reduction device and the deep reduction device in the whole reduction process; while ensuring efficient reduction of iron oxides, minimal consumption of fuel is achieved by the partitioning of the reduction stage; meanwhile, the consumption of fuel is reduced, and the generation of polluted gas and waste residues is further reduced. Through the research and continuous experiments of the inventor, it is obtained that the total fuel consumption of the iron oxide per unit mass in the whole reduction process is most economical when the reduction degree of the iron oxide in the pre-reduction device is controlled to be eta, and eta is 40-80%, preferably 50-70%, and more preferably 60-65%. Therefore, by precisely controlling the stages of the respective reduction of the iron oxide in the two reduction processes, i.e., controlling the degree of reduction of the iron oxide in the pre-reduction apparatus (the rest of the reduction stages are completed in the deep reduction apparatus), energy-saving reduction of the iron oxide can be achieved.

In the invention, the reduction degree of the iron oxide in the pre-reduction device can be controlled by controlling the carbon distribution amount in the iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device, the reduction temperature in the pre-reduction device and other means. Under the condition that other conditions are unchanged, the higher the carbon distribution amount in the iron oxide is, the higher the reduction degree of the oxide in the pre-reduction device is; the longer the heat preservation reduction time of the iron oxide in the pre-reduction device is, the larger the reduction degree of the oxide in the pre-reduction device is; the higher the reduction temperature in the pre-reduction unit, the greater the degree of reduction of the iron oxide in the pre-reduction unit.

Through continuous researches of the inventor of the technical scheme, under the premise of realizing the reduction degree eta of 40-80%, preferably 50-70%, more preferably 60-65%, the optimal technological conditions of carbon distribution amount in the oxide, heat preservation reduction time of the iron oxide in the pre-reduction device and reduction temperature in the pre-reduction device are obtained, and the energy maximization utilization of the pre-reduction device can be realized, so that the technological conditions of saving fuel most are obtained. Controlling the carbon compounding amount in the iron oxide to be 10-40wt%, preferably 15-30wt%, more preferably 20-25wt%; further preferably 20-25%; for example 20%,21%,22%,23%,24%,25%. Controlling the heat preservation reduction time of the iron oxide in the pre-reduction device to be 60-180min, preferably 70-140min, more preferably 90-120min; for example: 80min,90min,100min,110min,120min. The reduction temperature in the pre-reduction apparatus is controlled to be 800-1400 ℃, preferably 850-1300 ℃, more preferably 900-1200 ℃. For example: 900 ℃,1000 ℃,1050 ℃,1100 ℃,1150 ℃,1200 ℃,1300 ℃,1400 ℃. The reduction degree of the iron oxide in the pre-reduction device is realized by controlling the process conditions in the pre-reduction device and the carbon distribution amount in the iron oxide; but also can reduce the fuel consumption of the iron oxide reduction in the pre-reduction device.

Preferably, the pre-reduction product of the pre-reduction device enters the gas reforming vertical shaft after being discharged from the kiln head, the material in the reforming vertical shaft moves downwards until being discharged out of the vertical shaft through the discharge hole, the gas at the top of the deep reduction device is introduced into the gas reforming vertical shaft through a plurality of branch pipes after being dedusted through a plurality of pipes, and the opening is arranged below the branch pipes, so that the material is ensured not to fall into the branch pipes to cause blockage. The gas moves upwards in the vertical shaft material layer and forms countercurrent movement with the descending pre-reduction material.

In the present invention, process conditions within the deep reduction apparatus may be controlled, for example: and controlling technological parameters such as the coal injection amount in the deep reduction device, the gas input amount in the deep reduction device and the like, so as to adjust the temperature of high-temperature gas discharged by the deep reduction device. In order to achieve reforming of the high temperature gas in the reforming shaft and further reduction of the pre-reduced product by the high-split gas in the reforming shaft, the temperature of the high temperature gas exiting the deep reduction device is preferably controlled to be greater than 1400 ℃, preferably greater than 1500 ℃, more preferably greater than 1600 ℃. For example: 1400 ℃,1450 ℃,1500 ℃,1550 ℃,1600 ℃,1650 ℃,1700 ℃,1800 ℃.

In the invention, reformed high-temperature coal gas is conveyed into the rotary kiln, and the heat is provided and simultaneously the high-temperature coal gas mainly plays a role of a reducing agent. The content of the reducing gas in the reformed high-temperature gas obtained after passing through the reforming shaft can be controlled by controlling the flow rate of the high-temperature gas discharged from the deep reduction device in the reforming shaft, the temperature of the high-temperature gas entering the reforming shaft and other technological parameters. In order to ensure the reduction of the reformed high-temperature gas in the pre-reduction device and also to ensure the pre-reduction degree of the iron oxide in the pre-reduction device, in the invention, the content of CO in the reformed high-temperature gas is controlled to be higher than 30vol%, and preferably the content of CO is controlled to be higher than 35vol%. H ₂ The content of (C) is higher than 2vol%, preferably H ₂ The content of (C) is higher than 3vol%, more preferably H ₂ The content of (2) is higher than 5vol%.

In the invention, the pre-reduction device is a device for carrying out pre-reduction reaction on the iron oxide, and plays roles and aims at pre-reducing the iron oxide, so that Fe which is easy to occur in the process of reducing the iron oxide into metallic iron ₂ O ₃ →Fe ₃ O ₄ →Fe _x The reduction reaction in the O stage is completed in the pre-reduction apparatus as long as the apparatus or system for the reduction reaction of iron oxide can occur. The invention realizes the reduction degree control of the pre-reduction reaction of the iron oxide by controlling the reduction degree of the iron oxide in the pre-reduction device. In engineering application, the most commonly used prereducing device isRotary kilns, rotary hearth kilns, tunnel kilns, fluidized beds or shaft furnaces. The rotary kiln, rotary hearth furnace, tunnel kiln, fluidized bed or shaft furnace can realize the pre-reduction process of iron oxide, and can control the reduction degree of the iron oxide in the rotary kiln, rotary hearth furnace, tunnel kiln, fluidized bed or shaft furnace for reduction reaction.

In the invention, the deep reduction device is a device for carrying out deep reduction reaction on a pre-reduction product. The deep reduction device has the function and the purpose that the pre-reduction product is subjected to deep reduction reaction, the pre-reduction product with a certain reduction degree and residual coal are hot packed into the deep reduction device, and Fe occurs in the deep reduction device _x Deep reduction reaction of O-Fe stage. Provided that the apparatus or system is capable of undergoing an iron oxide reduction reaction. In engineering applications, the most commonly used deep reduction device may be a smelting reduction furnace, a converter, an electric furnace or a blast furnace. The deep reduction process of the iron oxide can be realized by a smelting reduction furnace, a converter, an electric furnace or a blast furnace.

The technology completes the reaction of the easy reduction stage of the iron oxide from trivalent to divalent (part of trivalent iron is reduced to zero valence) in a pre-reduction device, and the reaction of the difficult reduction stage of the iron oxide (or most of the iron oxide) from divalent to zero valence is completed in a deep reduction device.

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

1. the technology adopts a method of pre-reduction by a pre-reduction device and deep reduction by a deep reduction device to reduce iron oxide into Fe which is easy to occur in the process of metallic iron ₂ O ₃ →Fe ₃ O ₄ →Fe _x The reduction reaction of the O stage is completed in a pre-reduction device, and the pre-reduction product reaching a certain reduction degree and the residual coal are hot packed together and enter a deep reduction device for deep reduction.

2. The invention realizes the high efficiency of the whole reduction process of the iron oxide by controlling the reduction degree of the iron oxide in the two-step reduction process of the pre-reduction-deep reduction device deep reduction of the pre-reduction device. The reduction degree of the iron oxide in the pre-reduction device is controlled, so that the iron oxide is reasonably distributed in the pre-reduction device and the deep reduction device in the whole reduction process; while ensuring efficient reduction of iron oxides, minimal consumption of fuel is achieved by the partitioning of the reduction stage; meanwhile, the consumption of fuel is reduced, and the generation of polluted gas and waste residues is further reduced.

3. The invention utilizes the melting reduction process to generate a large amount of high-temperature gas with the temperature of more than 1500 ℃, utilizes the sensible heat and the latent heat of the high-temperature gas and the reducing gas in the high-temperature gas to realize the pre-reduction of the iron oxide in the pre-reduction device, and can effectively reduce the energy consumption of the pre-reduction device.

4. According to the invention, the high-temperature gas is reformed through the reforming vertical shaft, so that the pre-reduction product is further reduced. The sensible heat of the pre-reduction product and the sensible heat of the high-temperature gas and the reducing gas in the sensible heat are fully utilized to realize the further pre-reduction of the iron oxide. In addition, in the reforming vertical shaft, the high Wen Can coal in the pre-reduction device and the CO2 and H in the high-temperature coal gas in the pre-reduction product are fully utilized ₂ O and CO generated by reduction of iron oxide in material layer ₂ And H ₂ O, gas reforming reaction occurs.

Drawings

FIG. 1 is a process flow diagram of a method for direct reduction of iron oxides according to the present invention;

FIG. 2 is a graph showing the effect of reduction temperature in a pre-reduction apparatus on the metallization rate (pre-reduction degree) in a process of a method for directly reducing iron oxides according to the present invention;

FIG. 3 is a graph showing the effect of reduction time in a pre-reduction apparatus on the metallization rate (pre-reduction degree) in a process of a method for directly reducing iron oxides according to the present invention;

Fig. 4 shows the effect of the amount of pit addition in iron oxide in the pre-reduction apparatus on the metallization rate (pre-reduction degree) in the process of the method for directly reducing iron oxide according to the present invention;

FIG. 5 is a schematic diagram of a direct iron oxide reduction system according to the present invention;

fig. 6 is a schematic structural view of a reforming shaft provided in an iron oxide direct reduction system according to the present invention.

Fig. 7 is a schematic structural view of the rotary kiln of the present invention.

FIG. 8 is a sectional view of rotary kiln B-B according to the invention.

Fig. 9 is a schematic perspective view of rotary kiln B-B according to the present invention.

FIG. 10 is a schematic view of the structure of the rotary kiln of the present invention provided with a conductivity detecting device.

Fig. 11 is a control flow chart of the pre-reduction of iron oxides in the pre-reduction apparatus according to the present invention.

Reference numerals:

1: a pre-reduction device; 101: a drying section; 102: a preheating section; 103: a reduction roasting section; 104: a slow cooling section; 2: a depth reduction device; 3: reforming shafts; 301: a feed inlet; 302: a discharge port; 303: an air inlet; 304: an air outlet; 4: a kiln body air duct mechanism; 401: an air inlet connecting piece; 402: a stop valve; 403: a pull rod; 404: an air inlet; 405: an air inlet channel; 5: an annular rotary slide rail; 501: a bracket; 6: a rotary sliding mechanism; 601: a rotary wheel seat; 602: a lateral rotation wheel; 603: a vertical rotating wheel; 7: a horizontal sliding mechanism; 701: a horizontal wheel seat; 702: a horizontal pulley; 703: a horizontal rail; 8: a slewing mechanism; 801: a rotary motor; 802: a large gear ring; 9: conductivity detection means; 901: a detection coil; 902: a magnetic core; a: and (5) a rotary kiln.

Detailed Description

The following examples illustrate the technical aspects of the invention, and the scope of the invention claimed includes but is not limited to the following examples.

An iron oxide direct reduction system or a system for use in the method described in the first embodiment, the system comprising a pre-reduction device 1 and a deep reduction device 2. Wherein, the discharge gate of pre-reduction device 1 communicates with the feed inlet of degree of depth reduction device 2, and the gas outlet of degree of depth reduction device 2 communicates to the air inlet of pre-reduction device 1.

Preferably, the system further comprises a reforming shaft 3. The reforming shaft 3 includes a feed port 301, a discharge port 302, an air inlet 303, and an air outlet 304. The discharge port of the prereducing device 1 is connected to the feed port 301 of the reforming shaft 3. The discharge port 302 of the reforming shaft 3 is connected to the feed port of the deep reduction device 2. The outlet of the deep reduction device 2 is connected to the inlet 303 of the reforming shaft 3. The air outlet 304 of the reforming shaft 3 communicates with the air inlet of the prereducing device 1.

Preferably, the pre-reduction device 1 is a rotary kiln, rotary hearth furnace, tunnel kiln, fluidized bed or shaft furnace. Preferably, the prereduction unit 1 is a rotary kiln.

Preferably, the deep reduction device 2 is a smelting reduction furnace, a converter, an electric furnace, or a blast furnace.

Preferably, the rotary kiln a includes a drying section 101, a preheating section 102, a reduction roasting section 103, and a slow cooling section 104. The air outlet 304 of the reforming shaft 3 is communicated with the reduction roasting section 103 and/or the preheating section 102 of the rotary kiln a.

Preferably, the rotary kiln A further comprises a kiln body air duct mechanism 4, an annular rotary sliding rail 5 and a rotary sliding mechanism 6. The annular rotary slide rail 5 is sleeved outside the rotary kiln a and is supported by a bracket 501. The wheel end of the rotary sliding mechanism 6 is connected with the annular rotary sliding rail 5, the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism 4, and the inner end of the kiln body air duct mechanism 4 is connected with the kiln wall. Namely, the rotary kiln A and the kiln body air duct mechanism 4 can simultaneously rotate on the annular rotary slide rail 5 through the rotary sliding mechanism 6.

Preferably, a plurality of annular rotary slide rails 5 are arranged outside the rotary kiln a. Any one annular rotary slide rail 5 is connected with the rotary kiln A through a plurality of rotary sliding mechanisms 6 and a plurality of kiln body air duct mechanisms 4.

Preferably, the kiln body air duct mechanism 4 comprises an air inlet connector 401, a baffle valve 402, a pull rod 403 and an air inlet 404. An air inlet channel 405 is formed in the kiln body of the rotary kiln A. One end of the baffle 402 extends into the air inlet channel 405, and the other end of the baffle is communicated with the air inlet connector 401. The air inlet 404 is formed on the air inlet connector 401. One end of the air inlet connecting piece 401, which is far away from the rotary kiln A, is connected with one end of a pull rod 403, and the other end of the pull rod 403 is connected with a rotary sliding mechanism 6.

Preferably, the rotary slide mechanism 6 includes a rotary wheel seat 601, a lateral rotary wheel 602, and a vertical rotary wheel 603. The rotary wheel seat 601 is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail 5. Lateral rotating wheels 602 are arranged on the rotating wheel seats 601 positioned on the side surfaces of the annular rotating slide rail 5. Vertical rotating wheels 603 are arranged on the rotating wheel seats 601 positioned on the outer bottom surface of the annular rotating slide rail 5. The rotary wheel seat 601 is rotatably slidable on the endless rotary slide rail 5 by a lateral rotary wheel 602 and a vertical rotary wheel 603.

Preferably, the rotary kiln a further comprises a horizontal sliding mechanism 7. The horizontal sliding mechanism 7 includes a horizontal wheel seat 701, a horizontal pulley 702, and a horizontal rail 703. The horizontal rail 703 is a groove-shaped rail provided at the upper end of the bracket 501. The bottom end of the horizontal wheel mount 701 is mounted in a horizontal track 703 by a horizontal pulley 702. The top end of the horizontal wheel seat 701 is connected with the annular rotary slide rail 5.

Preferably, the system further comprises a slewing mechanism 8. The swing mechanism 8 includes a swing motor 801 and a ring gear 802. The inner ring of the large gear ring 802 is fixed on the outer wall of the rotary kiln A, and the outer ring of the large gear ring 802 is meshed with a transmission gear of the rotary motor 801.

Preferably, the system further comprises conductivity detection means 9; the conductivity detection device 9 includes a detection coil 901 and a magnetically conductive core 902; the detection coil 901 is connected with a magnetic core 902, and the magnetic core 902 is arranged on the kiln body of the rotary kiln A.

Preferably, the magnetic core 902 is disposed in the side wall of the kiln body of the rotary kiln a, and the distance between the end of the magnetic core 902 and the inner wall of the rotary kiln a is 0.5-20mm, preferably 1-15mm, more preferably 2-10mm.

Experiment 1: experiment of total energy consumption of iron oxide reduction by controlling reduction degree in pre-reduction device

According to the reduction process of the iron oxide, the different pre-reduction degrees of the iron oxide in the pre-reduction device are controlled by combining the reduction degree theory of the iron oxide in the pre-reduction device and the specific process of direct reduction of the iron oxide, the pre-reduction products obtained by the iron oxide in the pre-reduction device through different pre-reduction degrees are calculated, and then the total energy consumption of reducing the iron oxide into molten iron is obtained by deep reduction through the deep reduction device.

14 tons of hematite from the same batch are divided into 14 batches, each weighing 1 ton. Each batch is respectively placed in a pre-reduction device (rotary kiln) for pre-reduction, and the pre-reduction degrees of the pre-reduction devices (rotary kiln) are controlled to be different; then respectively conveying pre-reduction products discharged from a pre-reduction device (rotary kiln) into a deep reduction device for deep reduction (fusion reduction), and controlling the same technological conditions for the deep reduction in the deep reduction device to obtain molten iron; and calculating the energy consumption of prereducing each batch of iron oxide in a prereducing device (rotary kiln), the energy consumption of the prereducing product in the batch entering into a deep reducing device for deep reduction, and then calculating the total energy consumption of the iron oxide in the batch in the whole reducing process. The results were specifically as follows:

Experiments prove that under the condition that the reduction degree eta of the iron oxide in the pre-reduction device (rotary kiln) is controlled to be 40-80%, preferably 50-70%, more preferably 60-65%, the total energy consumption is the least, namely the most energy-saving.

Experiment 2: experiment of influence of carbon amount in iron oxide in prereducing apparatus on reduction degree of iron oxide

The same batch of hematite was divided into 5 batches, each weighing 1 ton. Each batch of hematite is mixed with pulverized coal with different weight ratios; and then placing each batch in a pre-reduction device (rotary kiln) respectively for pre-reduction, controlling other process conditions (except carbon distribution amount) of the pre-reduction device (rotary kiln) for pre-reduction to be the same, and detecting the reduction degree of the pre-reduced product of each batch after the pre-reduction device (rotary kiln) pre-reduction.

The method for detecting the reduction degree comprises the following steps: a low-temperature rapid reduction detection method, namely a non-contact temperature measurement and material component detection device and method based on conductivity. The detection of the conductivity of the material mainly adopts an eddy current detection method, a detection coil is arranged above a test piece of the metal material, an alternating excitation signal is added into the coil, an alternating magnetic field is generated around the coil, a metal conductor arranged in the magnetic field generates eddy currents, the eddy currents also generate magnetic fields, the directions of the eddy currents are opposite, the effective impedance of the electrified coil changes due to the reaction of the magnetic fields, and the change of the impedance of the coil completely and uniquely reflects the eddy current effect of an object to be detected. The detection environment is kept unchanged, when materials with different conductivities are detected, the influence on the impedance of the detection coil is different due to the different sizes of eddy currents generated by the surface layer, so that the conductivity of the metal material can be measured by measuring the change condition of the impedance of the coil. The degree of reduction of the iron oxide was calculated by conductivity.

The specific results are as follows:

the amount of carbon incorporation in the iron oxide and the degree of reduction of the iron oxide were obtained by combining the experimental data and are shown in fig. 4.

Experiment 3: experiment of influence of thermal insulation reduction time of iron oxide in pre-reduction device on reduction degree of iron oxide

The same batch of hematite was divided into 5 batches, each weighing 1 ton. Each batch is placed in a pre-reduction device (rotary kiln) to be pre-reduced, the heat preservation reduction time of iron oxide in the pre-reduction device (rotary kiln) is controlled to be different, other process conditions (except the heat preservation reduction time) for controlling the pre-reduction device (rotary kiln) to be pre-reduced are the same, and the reduction degree of a pre-reduced product of each batch after being pre-reduced by the pre-reduction device (rotary kiln) is detected. The method is the same as described above.

The specific results are as follows:

combining the experimental data, the thermal insulation reduction time of the iron oxide in the pre-reduction device (rotary kiln) and the reduction degree of the iron oxide are obtained as shown in figure 3.

Experiment 4: experiment of influence of thermal insulation reduction time of iron oxide in pre-reduction device on reduction degree of iron oxide

The same batch of hematite was divided into 5 batches, each weighing 1 ton. Each batch is placed in a pre-reduction device (rotary kiln) to be pre-reduced, the reduction temperature of a reduction roasting section of iron oxide in the pre-reduction device (rotary kiln) is controlled to be different, other process conditions (except the temperature in the rotary kiln) for pre-reduction of the pre-reduction device (rotary kiln) are controlled to be the same, and the reduction degree of a pre-reduced product of each batch after the pre-reduction of the pre-reduction device (rotary kiln) is detected. The method is the same as described above.

The specific results are as follows:

the experimental data are combined to obtain the reduction temperature and the reduction degree of the iron oxide in the reduction roasting section in the pre-reduction device (rotary kiln) in the iron oxide as shown in figure 2.

Example 1

Firstly, pre-reducing the iron oxide by a pre-reduction device to obtain a pre-reduction product; and then carrying out deep reduction on the pre-reduction product by a deep reduction device to obtain molten iron.

Example 2

Firstly, pre-reducing the iron oxide by a pre-reduction device to obtain a pre-reduction product; then carrying out deep reduction on the pre-reduction product by a deep reduction device to obtain molten iron; in the deep reduction device, the pre-reduction product reacts with carbon to obtain molten iron and high-temperature gas; the high-temperature gas is conveyed into a rotary kiln to serve as a combustion heat source and reducing gas, and the high-temperature gas and iron oxide undergo a reduction reaction in a pre-reduction device.

Example 3

Example 2 was repeated except that the high temperature gas was fed to the pre-reduction unit after the gas reforming process. The method comprises the following steps: the pre-reduction product obtained by pre-reduction in the pre-reduction device enters a reforming shaft, the material flows downwards in the reforming shaft from top to bottom, and is discharged from the bottom of the reforming shaft to enter a deep reduction device; the high-temperature gas generated in the deep reduction device enters from the lower part or the bottom of the reforming vertical shaft, contacts with the pre-reduction product in the deep reduction device, and generates a Budder reaction and a water gas reaction to realize reforming, and the reformed high-temperature gas is conveyed into the pre-reduction device to be used as reducing gas.

Example 4

Example 3 was repeated except that the high temperature gas generated in the deep reduction apparatus was transferred to the reforming shaft after dust removal.

Example 5

Example 4 was repeated except that the temperature of the high temperature gas exiting the deep reduction device was greater than 1400 ℃.

Example 5

Example 4 was repeated except that the temperature of the high temperature gas exiting the deep reduction device was greater than 1500 ℃.

Example 7

Example 3 was repeated, except that the CO content of the reformed high-temperature gas obtained after passing through the reforming shaft was controlled to be higher than 35vol%, H ₂ The content of (2) is higher than 2vol%.

Example 8

Example 3 was repeated, except that the CO content of the reformed high-temperature gas obtained after passing through the reforming shaft was controlled to be higher than 50vol%, H ₂ The content of (2) is higher than 5vol%.

Example 9

Example 7 was repeated, the reaction of the iron oxide in the pre-reduction unit taking place as follows:

xFe ₂ O _3(s) +(3x-2)CO _(g) ＝2Fe _x O _(s) +(3x-2)CO _2(g) ，

xFe ₂ O _3(s) +(3x-2)H _2(g) ＝2Fe _x O _(s) +(3x-2)H ₂ O _(g) ，

Fe ₂ O _3(s) +3CO _(g) ＝2Fe _(s) +3CO _2(g) ，

Fe ₂ O _3(s) +3H _2(g) ＝2Fe _(s) +3H ₂ O _(g) ；

the reduction degree of the iron oxide in the pre-reduction device was controlled to be 60%.

Example 10

Example 9 was repeated except that the degree of reduction of iron oxide in the pre-reduction apparatus was controlled to be 65%.

Example 11

Example 9 was repeated except that the degree of reduction of iron oxide in the pre-reduction apparatus was controlled to be 55%.

Example 12

Example 9 was repeated except that the degree of reduction of iron oxide in the pre-reduction apparatus was controlled to be 70%.

Example 13

Example 7 is repeated, wherein the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity; controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 8 x 10 ⁶ Ω ^-1 ·m ^-1 。

Example 14

Example 7 is repeated, wherein the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity; controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 2 x 10 ⁵ Ω ^-1 ·m ^-1 。

Example 15

Example 7 is repeated, wherein the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity; controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 9 x 10 ⁶ Ω ^-1 ·m ^-1 。

Example 16

Example 7 is repeated, wherein the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity; controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 4 x 10 ⁶ Ω ^-1 ·m ^-1 。

Example 17

Example 7 was repeated except that the carbon distribution amount in the iron oxide was controlled to 22wt%, the heat-retaining reduction time of the iron oxide in the pre-reduction apparatus was controlled to 100min, and the reduction temperature in the pre-reduction apparatus was controlled to 1100 ℃.

Example 18

Example 7 was repeated except that the carbon distribution amount in the iron oxide was controlled to 18wt%, the thermal reduction time of the iron oxide in the pre-reduction apparatus was controlled to 130min, and the reduction temperature in the pre-reduction apparatus was controlled to 1250 ℃.

Example 19

Example 7 was repeated except that the carbon content in the iron oxide was controlled to 30wt%, the thermal reduction time of the iron oxide in the pre-reduction apparatus was controlled to 750min, and the reduction temperature in the pre-reduction apparatus was controlled to 850 ℃.

Example 20

In detection example 7, the pre-reduction is performed by a pre-reduction device to obtain a pre-reduction product, and the real-time conductivity sigma of the material in the pre-reduction device is detected in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method specifically comprises the following steps:

if sigma _{Time of day} ≤0.1Ω ^-1 ·m ^-1 Indicating that the main Fe of the materials in the pre-reduction device ₂ O ₃ In the pre-reduction unit, the real-time reduction degree of the iron oxide in the pre-reduction unit is [0,1 ] ]；

If 0.1 < sigma _{Time of day} ≤1000Ω ^-1 ·m ^-1 Indicating the material in the prereducing deviceMain Fe ₃ O ₄ In the pre-reduction unit, the real-time reduction degree of the iron oxide in the pre-reduction unit is (1, 11.1 percent)]；

Example 21

According to the detection result of example 20, the real-time reduction degree η of the iron oxide in the pre-reduction device _{Real world} Adjusting the technological conditions of reduction of the iron oxide in the pre-reduction device; the method comprises the following steps:

if eta _{Real world} = (1 plus or minus 10%) eta, keeping the carbon distribution amount in the existing iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the rotary kiln to continue to operate;

Example 22

In example 21, the reduction of the reduction temperature in the pre-reduction unit is achieved by: reducing the coal injection amount in the pre-reduction device and/or reducing the secondary air inlet amount of the pre-reduction device; the raising of the reduction temperature in the pre-reduction device is achieved by: increasing the coal injection amount in the pre-reduction device and/or increasing the secondary air inlet amount of the rotary kiln; the heat preservation reduction time of the iron oxide in the pre-reduction device is shortened by increasing the rotating speed of the pre-reduction device; the heat preservation reduction time of the iron oxide in the pre-reduction device is prolonged by reducing the rotating speed of the pre-reduction device.

Example 23

In example 22, the specific operations are:

the carbon distribution amount in the iron oxide is specifically reduced as follows: each decrease in the amount of carbon incorporation Δm=10% m ₁ Wherein m is ₁ The original carbon distribution amount in the iron oxide is calculated; i.e. if eta _{Real world} > (1+10%) eta, controlling carbon distribution quantity m of next batch of iron oxide _i ＝m _i-1 Syndrome of deficiency m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the carbon distribution quantity delta m in the iron oxide of the next batch is reduced again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η；

The carbon distribution amount in the iron oxide is specifically improved as follows: each increment delta m of carbon compounding amount ₀ ＝10％m ₁ Wherein m is ₁ The original carbon distribution amount in the iron oxide is calculated; i.e. if eta _{Real world} < (1+10%) eta, controlling carbon distribution quantity m in next batch of iron oxide _i ＝m _i-1 A + [ delta ] m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Is still smallAt (1+10%) η, the carbon distribution quantity Deltam in the iron oxide of next batch is increased again until the real-time reduction degree of the iron oxide in the pre-reduction device is reached _{Real world} ＝(1±10％)η。

Example 24

In example 22, the specific operations are: the coal injection amount in the pre-reduction device is specifically reduced as follows: each reduction of the coal injection amount Δp=10% p ₁ Wherein p is ₁ The original coal injection amount in the pre-reduction device; i.e. if eta _{Real world} > (1+10%) eta, controlling coal injection quantity p in the prereduction equipment _j ＝p _j-1 - Δp; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the coal injection quantity delta p is reduced again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η；

The coal injection amount in the pre-reduction device is increased specifically as follows: each increment Δp=10%p of coal injection amount ₁ Wherein p is ₁ The original coal injection amount in the pre-reduction device; i.e. if eta _{Real world} < (1+10%) eta, and the coal injection quantity p in the prereduction device _j ＝p _j-1 A + [ delta ] p; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the coal injection quantity delta p is increased again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

Example 25

In example 22, the specific operations are: the secondary air inlet amount of the rotary kiln is reduced specifically as follows: each reduction of secondary air intake Δf=10% f ₁ Wherein f ₁ The primary secondary air intake of the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling secondary air quantity f of rotary kiln _k ＝f _k-1 - Δf; then continue to detect the revolution in real timeReal-time conductivity sigma of material in kiln _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the secondary air inlet quantity delta f is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η；

The secondary air inlet of the rotary kiln is increased specifically as follows: each increment Δf=10% f of the secondary air intake ₁ Wherein f ₁ The primary secondary air intake of the rotary kiln; i.e. if eta _{Real world} And (1+10%) eta, controlling secondary air quantity f of rotary kiln _k ＝f _k-1 A + [ delta ] f; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the secondary air inlet quantity delta f is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Example 26

In example 22, the specific operations are: the rotating speed of the rotary kiln is increased specifically as follows: each increment Δs=10%s of rotation speed ₁ Wherein s is ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 A + [ delta ] s; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the rotating speed delta s is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η；

The rotating speed of the rotary kiln is reduced specifically as follows: each decrease in rotational speed Δs=10%s ₁ Wherein s is ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 - Δs; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining ironReal-time reduction degree eta of oxide in rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the rotating speed delta s is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

Example 27

As shown in fig. 5, an iron oxide direct reduction system includes a pre-reduction device 1 and a deep reduction device 2; wherein, the discharge gate of pre-reduction device 1 communicates with the feed inlet of degree of depth reduction device 2, and the gas outlet of degree of depth reduction device 2 communicates to the air inlet of pre-reduction device 1. The deep reduction device 2 is a smelting reduction furnace.

Example 28

As shown in fig. 6, an iron oxide direct reduction system includes a pre-reduction device 1 and a deep reduction device 2; wherein, the discharge gate of pre-reduction device 1 communicates with the feed inlet of degree of depth reduction device 2, and the gas outlet of degree of depth reduction device 2 communicates to the air inlet of pre-reduction device 1.

The system also comprises a reforming shaft 3; the reforming vertical shaft 3 comprises a feed inlet 301, a discharge outlet 302, an air inlet 303 and an air outlet 304; the discharge port of the pre-reduction device 1 is communicated with the feed port 301 of the reforming vertical shaft 3; the discharge port 302 of the reforming vertical shaft 3 is communicated with the feed port of the deep reduction device 2; the air outlet of the deep reduction device 2 is communicated with the air inlet 303 of the reforming vertical shaft 3; the air outlet 304 of the reforming shaft 3 communicates with the air inlet of the prereducing device 1.

Example 29

Example 28 was repeated except that the prereduction unit 1 was rotary kiln a; the deep reduction device 2 is a smelting reduction furnace.

Example 30

Example 28 was repeated except that the pre-reduction device 1 was a rotating bed; the deep reduction device 2 is a converter.

Example 31

Example 28 was repeated except that the pre-reduction device 1 was a tunnel kiln; the depth reduction device 2 is an electric furnace.

Example 32

Example 28 was repeated except that the pre-reduction device 1 was a fluidized bed; the deep reduction device 2 is a blast furnace.

Example 33

Example 28 is repeated except that the pre-reduction device 1 is a coal-based shaft furnace; the deep reduction device 2 is a smelting reduction furnace.

Example 34

Example 28 is repeated except that the pre-reduction device 1 is a gas-based shaft furnace; the deep reduction device 2 is a smelting reduction furnace.

Example 35

Example 29 was repeated except that the prereducing device 1 was rotary kiln a; the rotary kiln A comprises a drying section 101, a preheating section 102, a reduction roasting section 103 and a slow cooling section 104; the air outlet 304 of the reforming shaft 3 is communicated to the reduction roasting section 103 of the rotary kiln a. The depth reduction device 2 is an electric furnace.

Example 36

Example 28 was repeated except that the prereduction unit 1 was rotary kiln a; the rotary kiln A comprises a drying section 101, a preheating section 102, a reduction roasting section 103 and a slow cooling section 104; the air outlet 304 of the reforming shaft 3 is connected to the preheating section 102 of the rotary kiln a. The deep reduction device 2 is a blast furnace.

Example 37

Example 28 was repeated except that the prereduction unit 1 was rotary kiln a; the rotary kiln A comprises a drying section 101, a preheating section 102, a reduction roasting section 103 and a slow cooling section 104; the air outlet 304 of the reforming shaft 3 is communicated with the reduction roasting section 103 and the preheating section 102 of the rotary kiln A.

Example 38

Example 37 is repeated, as shown in fig. 7, except that the rotary kiln a further comprises a kiln body air duct mechanism 4, an annular rotary slide rail 5 and a rotary slide mechanism 6. The annular rotary slide rail 5 is sleeved outside the rotary kiln a and is supported by a bracket 501. The wheel end of the rotary sliding mechanism 6 is connected with the annular rotary sliding rail 5, the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism 4, and the inner end of the kiln body air duct mechanism 4 is connected with the kiln wall. Namely, the rotary kiln A and the kiln body air duct mechanism 4 can simultaneously rotate on the annular rotary slide rail 5 through the rotary sliding mechanism 6.

Example 39

Embodiment 38 is repeated except that a plurality of annular rotary slide rails 5 are provided on the outside of the rotary kiln a. Any one annular rotary slide rail 5 is connected with the rotary kiln A through a plurality of rotary sliding mechanisms 6 and a plurality of kiln body air duct mechanisms 4.

Example 40

Example 39 is repeated as shown in fig. 8-9, except that the kiln body air duct mechanism 4 comprises an air inlet connector 401, a baffle valve 402, a pull rod 403 and an air inlet 404. An air inlet channel 405 is formed in the kiln body of the rotary kiln A. One end of the baffle 402 extends into the air inlet channel 405, and the other end of the baffle is communicated with the air inlet connector 401. The air inlet 404 is formed on the air inlet connector 401. One end of the air inlet connecting piece 401, which is far away from the rotary kiln A, is connected with one end of a pull rod 403, and the other end of the pull rod 403 is connected with a rotary sliding mechanism 6.

Example 41

The embodiment 40 is repeated except that the rotary slide mechanism 6 includes a rotary wheel seat 601, a lateral rotary wheel 602, and a vertical rotary wheel 603. The rotary wheel seat 601 is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail 5. Lateral rotating wheels 602 are arranged on the rotating wheel seats 601 positioned on the side surfaces of the annular rotating slide rail 5. Vertical rotating wheels 603 are arranged on the rotating wheel seats 601 positioned on the outer bottom surface of the annular rotating slide rail 5. The rotary wheel seat 601 is rotatably slidable on the endless rotary slide rail 5 by a lateral rotary wheel 602 and a vertical rotary wheel 603.

Example 42

Example 41 is repeated except that rotary kiln a further includes a horizontal sliding mechanism 7. The horizontal sliding mechanism 7 includes a horizontal wheel seat 701, a horizontal pulley 702, and a horizontal rail 703. The horizontal rail 703 is a groove-shaped rail provided at the upper end of the bracket 501. The bottom end of the horizontal wheel mount 701 is mounted in a horizontal track 703 by a horizontal pulley 702. The top end of the horizontal wheel seat 701 is connected with the annular rotary slide rail 5.

Example 43

Example 42 is repeated except that the system further comprises a swing mechanism 8. The swing mechanism 8 includes a swing motor 801 and a ring gear 802. The inner ring of the large gear ring 802 is fixed on the outer wall of the rotary kiln A, and the outer ring of the large gear ring 802 is meshed with a transmission gear of the rotary motor 801.

Example 44

Example 43 is repeated except that the system further comprises conductivity detection means 9; the conductivity detection device 9 includes a detection coil 901 and a magnetically conductive core 902; the detection coil 901 is connected with a magnetic conduction core 902, and the magnetic conduction core 902 is arranged on the kiln body of the rotary kiln A; the magnetic core 902 is arranged in the side wall of the kiln body of the rotary kiln A, and the distance between the tail end of the magnetic core 902 and the inner wall of the rotary kiln A is 3mm.

Example 45

Example 43 is repeated except that the system further comprises conductivity detection means 9; the conductivity detection device 9 includes a detection coil 901 and a magnetically conductive core 902; the detection coil 901 is connected with a magnetic conduction core 902, and the magnetic conduction core 902 is arranged on the kiln body of the rotary kiln A; the magnetic core 902 is arranged in the side wall of the kiln body of the rotary kiln A, and the distance between the tail end of the magnetic core 902 and the inner wall of the rotary kiln A is 10mm.

Example 46

The system described in example 11 was used for the direct reduction of hematite using the method described in example 4.

Example 47

The system described in example 11 was used for the direct reduction of magnetite using the method described in example 4.

Example 48

The system described in example 11 was used for the direct reduction of limonite using the method described in example 4.

Example 49

The system described in example 11 was used for the direct reduction of siderite using the method described in example 4.

Example 50

The system described in example 11 was used for the direct reduction of goethite using the method described in example 4.

Claims

1. A method for direct reduction of iron oxides, characterized by: firstly, pre-reducing iron oxide by a pre-reducing device to obtain a pre-reduced product; then carrying out deep reduction on the pre-reduction product by a deep reduction device to obtain molten iron; the reaction of iron oxide in the pre-reduction unit is:

xFe ₂ O _3(s) +(3x-2)CO _(g) ＝2Fe _x O _(s) +(3x-2)CO _2(g) ，

xFe ₂ O _3(s) +(3x-2)H _2(g) ＝2Fe _x O _(s) +(3x-2)H ₂ O _(g) ，

Fe ₂ O _3(s) +3CO _(g) ＝2Fe _(s) +3CO _2(g) ，

Fe ₂ O _3(s) +3H _2(g) ＝2Fe _(s) +3H ₂ O _(g) ；

controlling the reduction degree of the iron oxide in the pre-reduction device to be eta, wherein eta is 40-80%; wherein:x is E [2/3, + ]; controlling the reduction degree of the iron oxide in the pre-reduction device by controlling one or more of the carbon distribution amount in the iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device; the reduction degree of the iron oxide in the pre-reduction device is in direct proportion to the carbon distribution amount in the iron oxide, the heat preservation reduction time of the iron oxide in the pre-reduction device and the reduction temperature in the pre-reduction device; the carbon distribution amount in the iron oxide is controlled to be 10-40wt%, the heat preservation reduction time of the iron oxide in the pre-reduction device is controlled to be 60-180min, and the reduction temperature in the pre-reduction device is controlled to be 800-1400 ℃.

2. The method for direct reduction of iron oxides according to claim 1, characterized in that: in the deep reduction device, the pre-reduction product reacts with carbon to obtain molten iron and high-temperature gas; the high-temperature gas is conveyed into a pre-reduction device to be used as a combustion heat source and a reducing gas, and the high-temperature gas and iron oxide are subjected to reduction reaction in the pre-reduction device.

3. The method for direct reduction of iron oxides according to claim 2, characterized in that: and conveying the high-temperature gas to a pre-reduction device after the gas reforming process.

4. The method for direct reduction of iron oxides according to claim 1, characterized in that: eta is 50 to 70 percent.

5. The method for direct reduction of iron oxides according to claim 4, wherein: eta is 60 to 65 percent.

6. The method for direct reduction of iron oxides according to claim 1, characterized in that: the reduction condition of the iron oxide in the pre-reduction device is monitored by detecting the conductivity of the material in the pre-reduction device in real time and analyzing the state of the material in the pre-reduction device through the conductivity.

7. The method for direct reduction of iron oxides according to claim 6, characterized in that: controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 1 x 10 ⁵ -1*10 ⁷ Ω ^-1 ·m ^-1 。

8. The method for direct reduction of iron oxides according to claim 6, characterized in that: controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 3 x 10 ⁵ -7*10 ⁶ 。

9. The method for direct reduction of iron oxides according to claim 6, characterized in that: controlling the conductivity of the pre-reduced product obtained by reducing the iron oxide by a pre-reduction device to be 5 x 10 ⁵ -5*1*10 ⁶ Ω ^-1 ·m ^-1 。

10. The method for direct reduction of iron oxides according to claim 1, characterized in that: controlling the carbon distribution amount in the iron oxide to be 15-30wt%, wherein the carbon distribution amount is the weight ratio of the coal carbon in the iron oxide entering the pre-reduction device to the whole iron oxide; and/or

Controlling the thermal insulation reduction time of the iron oxide in the pre-reduction device to be 70-140min, wherein the thermal insulation reduction time of the iron oxide in the pre-reduction device refers to the residence time of the iron oxide in the highest temperature section of the rotary kiln; and/or

The reduction temperature in the pre-reduction device is controlled to be 850-1300 ℃, and the reduction temperature in the pre-reduction device refers to the highest temperature zone in the pre-reduction device.

11. The method for direct reduction of iron oxides according to claim 10, characterized in that: controlling the carbon compounding amount in the iron oxide to be 20-25wt%; controlling the heat preservation reduction time of the iron oxide in the pre-reduction device to be 90-120min; the reduction temperature in the pre-reduction device is controlled to be 900-1200 ℃.

12. The method for direct reduction of iron oxides according to claim 6, characterized in that: real-time conductivity sigma of material in real-time detection pre-reduction device _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method specifically comprises the following steps:

If 1000 < sigma _{Time of day} ≤1*10 ⁵ Ω ^-1 ·m ^-1 Indicating that the material in the pre-reduction device exists in the form of main FeO, and the iron oxide is in the pre-reduction deviceThe real-time reduction degree in the reduction device was (11.1%, 33.3%)]；

13. The method for direct reduction of iron oxides according to claim 12, characterized in that: according to the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} Adjusting the technological conditions of reduction of the iron oxide in the pre-reduction device; the method comprises the following steps:

14. The method for direct reduction of iron oxides according to any one of claims 1 to 13, characterized in that: the pre-reduction device is a rotary kiln, a rotary hearth furnace, a tunnel kiln, a fluidized bed or a shaft furnace; and/or

The deep reduction device (2) is a smelting reduction furnace, a converter, an electric furnace or a blast furnace.

15. The method for direct reduction of iron oxides according to claim 14, wherein: the pre-reduction device is a rotary kiln.

16. The method for direct reduction of iron oxides according to claim 14, wherein: the reduction of the reduction temperature in the pre-reduction device is achieved by the following means: reducing the coal injection amount in the rotary kiln and/or reducing the secondary air inlet amount of the rotary kiln; the raising of the reduction temperature in the pre-reduction device is achieved by: increasing the coal injection amount in the rotary kiln and/or increasing the secondary air inlet amount of the rotary kiln; and/or

The heat preservation reduction time of the iron oxide in the pre-reduction device is shortened by increasing the rotating speed of the rotary kiln; the heat preservation reduction time of the iron oxide in the pre-reduction device is prolonged by reducing the rotating speed of the rotary kiln.

17. The method for direct reduction of iron oxides according to claim 16, wherein: the carbon distribution amount in the iron oxide is specifically reduced as follows: each decrease in the amount of carbon incorporation Δm=10% m ₁ Wherein m is ₁ The original carbon distribution amount in the iron oxide is calculated; i.e. if eta _{Real world} > (1+10%) eta, controlling carbon distribution quantity m of next batch of iron oxide _i ＝m _i-1 Syndrome of deficiency m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the carbon distribution quantity delta m in the iron oxide of the next batch is reduced again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η；

The carbon distribution amount in the iron oxide is specifically improved as follows: each increment delta m of carbon compounding amount ₀ ＝10％m ₁ Wherein m is ₁ The original carbon distribution amount in the iron oxide is calculated; i.e. if eta _{Real world} < (1+10%) eta, controlling carbon distribution quantity m in next batch of iron oxide _i ＝m _i-1 A + [ delta ] m; then continuously detecting the real-time conductivity sigma of the material in the prereducing device in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the carbon distribution quantity delta m in the iron oxide of the next batch is increased again until the real-time reduction degree eta of the iron oxide in the pre-reduction device _{Real world} ＝(1±10％)η。

18. The method for direct reduction of iron oxides according to claim 16, wherein: the coal injection amount in the rotary kiln is specifically reduced: each reduction of the coal injection amount Δp=10% p ₁ Wherein p is ₁ The original coal injection amount in the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling coal injection quantity p in the rotary kiln _j ＝p _j-1 - Δp; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the coal injection quantity delta p is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η；

The method for increasing the coal injection amount in the rotary kiln comprises the following steps: each increment Δp=10%p of coal injection amount ₁ Wherein p is ₁ The original coal injection amount in the rotary kiln; i.e. if eta _{Real world} < (1+10%) eta, and the coal injection quantity p in the rotary kiln _j ＝p _j-1 A + [ delta ] p; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the coal injection quantity delta p is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

19. The method for direct reduction of iron oxides according to claim 16, wherein: the secondary air inlet amount of the rotary kiln is reduced specifically as follows: each reduction of secondary air intake Δf=10% f ₁ Wherein f ₁ The primary secondary air intake of the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling secondary air quantity f of rotary kiln _k ＝f _k-1 - Δf; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than (1+10%) eta, the secondary air inlet quantity delta f is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η；

20. The method for direct reduction of iron oxides according to claim 16, wherein: the rotating speed of the rotary kiln is increased specifically as follows: each increment Δs=10%s of rotation speed ₁ Wherein s is ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} > (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 A + [ delta ] s; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still greater than(1+10%) eta, the rotating speed delta s is increased again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η；

The rotating speed of the rotary kiln is reduced specifically as follows: each decrease in rotational speed Δs=10%s ₁ Wherein s is ₁ The original rotation speed of the rotary kiln; i.e. if eta _{Real world} (1+10%) eta, controlling rotation speed s of rotary kiln _r ＝s _r-1 - Δs; then continuously detecting the real-time conductivity sigma of the material in the rotary kiln in real time _{Time of day} Obtaining the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} The method comprises the steps of carrying out a first treatment on the surface of the If eta of the real-time state _{Real world} Still smaller than (1+10%) eta, the rotating speed delta s is reduced again until the real-time reduction degree eta of the iron oxide in the rotary kiln _{Real world} ＝(1±10％)η。

21. A method for direct reduction of iron oxides according to claim 3, characterized in that: the high-temperature gas is conveyed to a pre-reduction device after a gas reforming process, and specifically comprises the following steps: the pre-reduction product obtained by pre-reduction in the pre-reduction device enters a reforming shaft, the material flows downwards in the reforming shaft from top to bottom, and is discharged from the bottom of the reforming shaft to enter a deep reduction device; the high-temperature gas generated in the deep reduction device enters from the lower part or the bottom of the reforming vertical shaft, contacts with the pre-reduction product in the deep reduction device, and generates a Budder reaction and a water gas reaction to realize reforming, and the reformed high-temperature gas is conveyed into the pre-reduction device to be used as reducing gas.

22. The method for direct reduction of iron oxides according to claim 21, wherein: the high-temperature gas generated in the deep reduction device is conveyed to the reforming vertical shaft after dust removal.

23. The method for direct reduction of iron oxides according to claim 21 or 22, characterized in that: the temperature of the high-temperature gas discharged from the deep reduction device is more than 1400 ℃; and/or

CO in reformed high-temperature gas obtained after passing through reforming vertical shaftThe content of (2) is higher than 30vol%; h ₂ The content of (2) is higher than 2vol%.

24. The method for direct reduction of iron oxides as set forth in claim 23 wherein: the temperature of the high-temperature gas discharged from the deep reduction device is higher than 1500 ℃; and/or

The content of CO in the reformed high-temperature gas obtained after passing through the reforming vertical shaft is higher than 35vol%; h ₂ The content of (2) is higher than 3vol%.

25. The method for direct reduction of iron oxides of claim 24 wherein: the temperature of the high-temperature gas discharged from the deep reduction device is higher than 1600 ℃; and/or

H in reformed high-temperature gas obtained after passing through reforming vertical shaft ₂ The content of (2) is higher than 5vol%.

26. A system for the method of any one of claims 1-25, the system comprising a pre-reduction device (1) and a depth reduction device (2); wherein, the discharge port of the pre-reduction device (1) is communicated with the feed port of the deep reduction device (2), and the air outlet of the deep reduction device (2) is communicated to the air inlet of the pre-reduction device (1);

The system also comprises a reforming shaft (3); the reforming vertical shaft (3) comprises a feed inlet (301), a discharge outlet (302), an air inlet (303) and an air outlet (304); the discharge port of the pre-reduction device (1) is communicated with the feed port (301) of the reforming vertical shaft (3); a discharge hole (302) of the reforming vertical shaft (3) is communicated with a feed hole of the deep reduction device (2); the air outlet of the deep reduction device (2) is communicated with the air inlet (303) of the reforming vertical shaft (3); an air outlet (304) of the reforming vertical shaft (3) is communicated with an air inlet of the pre-reduction device (1); the pre-reduction device (1) comprises a drying section (101), a preheating section (102), a reduction roasting section (103) and a slow cooling section (104); the air outlet (304) of the reforming vertical shaft (3) is communicated with the reduction roasting section (103) and/or the preheating section (102) of the pre-reduction device (1).

27. The system according to claim 26, wherein: the pre-reduction device is a rotary kiln, a rotary hearth furnace, a tunnel kiln, a fluidized bed or a shaft furnace; and/or

28. The system according to claim 27, wherein: the prereduction device is a rotary kiln.

29. The system according to claim 28, wherein: the rotary kiln (A) further comprises a kiln body air duct mechanism (4), an annular rotary slide rail (5) and a rotary sliding mechanism (6); the annular rotary slide rail (5) is sleeved outside the rotary kiln (A) and is supported by the support (501); the wheel end of the rotary sliding mechanism (6) is connected with the annular rotary sliding rail (5), the other end of the rotary sliding mechanism is connected with the outer end of the kiln body air duct mechanism (4), and the inner end of the kiln body air duct mechanism (4) is connected with the kiln wall; namely, the rotary kiln (A) and the kiln body air duct mechanism (4) can simultaneously rotate on the annular rotary slide rail (5) through the rotary sliding mechanism (6).

30. The system according to claim 29, wherein: a plurality of annular rotary sliding rails (5) are arranged outside the rotary kiln (A); any one annular rotary slide rail (5) is connected with the rotary kiln (A) through a plurality of rotary sliding mechanisms (6) and a plurality of kiln body air duct mechanisms (4).

31. The system according to claim 29, wherein: the kiln body air duct mechanism (4) comprises an air inlet connecting piece (401), a stop valve (402), a pull rod (403) and an air inlet (404); an air inlet channel (405) is formed in the kiln body of the rotary kiln (A); one end of the stop valve (402) extends into the air inlet channel (405), and the other end of the stop valve is communicated with the air inlet connecting piece (401); the air inlet (404) is formed in the air inlet connecting piece (401); one end of the air inlet connecting piece (401) far away from the rotary kiln (A) is connected with one end of the pull rod (403), and the other end of the pull rod (403) is connected with the rotary sliding mechanism (6); and/or

The rotary sliding mechanism (6) comprises a rotary wheel seat (601), a lateral rotary wheel (602) and a vertical rotary wheel (603); the rotary wheel seat (601) is of a concave groove structure and is meshed with two side edge parts of the annular rotary slide rail (5); a lateral rotating wheel (602) is arranged on the rotating wheel seat (601) positioned on the side surface of the annular rotating slide rail (5); a vertical rotating wheel (603) is arranged on the rotating wheel seat (601) positioned on the outer bottom surface of the annular rotating slide rail (5); the rotary wheel seat (601) can rotationally slide on the annular rotary slide rail (5) through a lateral rotary wheel (602) and a vertical rotary wheel (603).

32. The system according to claim 31, wherein: the rotary kiln (A) also comprises a horizontal sliding mechanism (7); the horizontal sliding mechanism (7) comprises a horizontal wheel seat (701), a horizontal pulley (702) and a horizontal track (703); the horizontal track (703) is a groove-shaped track arranged at the upper end of the bracket (501); the bottom end of the horizontal wheel seat (701) is arranged in a horizontal track (703) through a horizontal pulley (702); the top end of the horizontal wheel seat (701) is connected with the annular rotary slide rail (5); and/or

The system further comprises a slewing mechanism (8); the slewing mechanism (8) comprises a slewing motor (801) and a large gear ring (802); the inner ring of the large gear ring (802) is fixed on the outer wall of the rotary kiln (A), and the outer ring of the large gear ring (802) is meshed and connected with a transmission gear of the rotary motor (801).

33. The system according to claim 31 or 32, wherein: the system further comprises conductivity detection means (9); the conductivity detection device (9) comprises a detection coil (901) and a magnetic conduction core (902); the detection coil (901) is connected with a magnetic conduction core (902), and the magnetic conduction core (902) is arranged on the kiln body of the rotary kiln (A).

34. The system according to claim 33, wherein: the magnetic conducting core (902) is arranged in the side wall of the kiln body of the rotary kiln (A), and the distance between the tail end of the magnetic conducting core (902) and the inner wall of the rotary kiln (A) is 0.5-20mm.

35. The system according to claim 34, wherein: the distance between the tail end of the magnetic core (902) and the inner wall of the rotary kiln (A) is 1-15mm.

36. The system according to claim 35, wherein: the distance between the tail end of the magnetic core (902) and the inner wall of the rotary kiln (A) is 2-10mm.

37. Use of the system of any one of claims 26-36 for the direct reduction of iron oxides; the iron oxide is one or more of hematite, magnetite, limonite, siderite and goethite.