CN113278790A

CN113278790A - Iron-containing material pretreatment and composite injection method and system

Info

Publication number: CN113278790A
Application number: CN202110460161.9A
Authority: CN
Inventors: 张冠琪; 张巧丽; 王金霞; 陈庆孟; 张晓峰
Original assignee: Shandong Molong Petroleum Machinery Co Ltd
Current assignee: Shandong Molong Petroleum Machinery Co Ltd
Priority date: 2021-04-27
Filing date: 2021-04-27
Publication date: 2021-08-20
Also published as: WO2022227801A1

Abstract

The application provides a method and a system for preprocessing and composite blowing of iron-containing materials, wherein the method comprises the following steps: (1) crushing and grinding the iron-containing material, and then performing dehydration drying treatment and primary preheating pre-reduction treatment on the iron-containing material; (2) carrying out secondary preheating pre-reduction treatment on the iron-containing material subjected to the primary preheating pre-reduction treatment; (3) premixing the coal dust, the flux and the iron-containing material subjected to the secondary preheating and pre-reduction treatment in an injection pipeline before injecting the iron-containing material into a smelting reduction furnace so as to preheat the coal dust and the flux by sensible heat carried by the iron-containing material; (4) and spraying and blowing the premixed mixture into a smelting reduction furnace. The method has high treatment efficiency on the iron-containing materials, short flow and high comprehensive utilization rate of energy, and can reduce the coal consumption of the iron bath smelting reduction process to below 850kg/t and increase the thermal efficiency by 3-5%.

Description

Iron-containing material pretreatment and composite injection method and system

Technical Field

The invention relates to the technical field of raw fuel pretreatment in a smelting reduction process, in particular to a method and a system for pretreatment and composite injection of iron-containing materials.

Background

The iron bath smelting reduction process is a smelting process for reducing iron oxide into metallic iron by using carbon in a high-temperature molten state by utilizing a smelting reduction metallurgy process of non-coking coal powder and iron ore powder, has the advantages of strong raw material adaptability, short process flow, small environmental pollution, good molten iron quality and the like, and is an advanced iron-making technology for solving the problems of poor coking coal resources and environmental protection in China.

The smelting reduction production process is mainly a two-step process, namely a pre-reduction process and a final reduction process. The fluidized bed technology applied to the iron bath smelting reduction process preheats the mineral powder by using high-temperature coal gas generated by the smelting reduction furnace, but the traditional fluidized bed process directly uses the coal gas generated by the smelting reduction furnace, the coal gas has high oxidation degree, poor quality and poor reduction capability, and the pre-reduction effect of the iron-containing material is poor due to the fact that the iron-containing material is pre-reduced only by a primary circulating fluidized bed, and the pre-reduction degree is lower than 20%.

Meanwhile, in the traditional iron bath smelting reduction process, coal powder and mineral powder are conveyed by adopting two different conveying pipelines, different solid spray guns are connected to blow the coal powder and the mineral powder into the smelting reduction furnace, the mixing effect of the coal powder and the mineral powder after the coal powder enters the smelting reduction furnace is poor, the charging temperature of the coal powder is low, the surface activity is low, and the heat transfer and mass transfer reaction rate of the smelting reduction reaction is seriously influenced. The coal powder firstly absorbs a large amount of heat to reach the reaction temperature, the melting reduction reaction is carried out, the reaction time is prolonged, the reaction is insufficient, and partial material particles are brought out of the furnace along with rising coal gas, so that the material waste is caused. The pretreatment stage of the raw fuel becomes a limiting link of the whole smelting reduction process.

Accordingly, there is a need to develop a new method and system for pre-treatment and combined injection of iron-containing materials to overcome and ameliorate one or more of the above disadvantages of the prior art, or at least to provide an effective alternative to solve the above problems.

Disclosure of Invention

Aiming at the defects, the invention provides a method and a system for preprocessing and compound blowing of iron-containing materials. The iron-containing material pretreatment and composite injection method and system can improve the preheating temperature of the iron-containing material and improve the pre-reduction degree of the iron-containing material, the iron-containing material is premixed with coal powder and a flux in a conveying pipeline, a large amount of sensible heat carried by the preheated iron-containing material is efficiently utilized to preheat the coal powder and the flux, the temperature of the coal powder entering a smelting reduction furnace is improved, the reaction condition of a smelting pool is optimized, the reaction rate of the smelting pool is improved, the production capacity of a smelting reduction process is effectively improved, the comprehensive utilization efficiency of energy is improved, the coal consumption is favorably reduced, and the energy consumption index of a smelting reduction technology is improved.

According to one aspect of the application, a method for preprocessing iron-containing materials and performing composite injection is provided, wherein the method comprises the following steps:

(1) crushing and grinding an iron-containing material, and then performing dehydration drying treatment and primary preheating pre-reduction treatment on the iron-containing material, wherein the temperature of first reducing gas in the primary preheating pre-reduction treatment is 500-700 ℃, and the CO content is 10-20%;

(2) carrying out secondary preheating pre-reduction treatment on the iron-containing material subjected to the primary preheating pre-reduction treatment, wherein the second reducing gas subjected to the secondary preheating pre-reduction treatment is modified coal gas, the temperature is 800-1000 ℃, the CO content is at least 50%, and the oxidation degree is not more than 20%;

(3) premixing the coal dust, the flux and the iron-containing material subjected to the secondary preheating pre-reduction treatment in an injection pipeline before injecting the iron-containing material into a smelting reduction furnace so as to preheat the coal dust and the flux by sensible heat carried by the iron-containing material;

(4) and spraying and blowing the premixed mixture into a melting reduction furnace, wherein the iron-containing material blowing carrier gas, the coal powder and flux blowing carrier gas and the mixed material blowing carrier gas are the first reduction waste gas of the primary preheating pre-reduction treatment.

In a preferred embodiment of the iron-containing material pretreatment and composite injection method, the dehydration drying treatment and primary preheating pre-reduction treatment of the iron-containing material comprise:

the iron-containing material enters a first section of fluidizing device through a first feed inlet at the lower part of the first section of fluidizing device, first reducing gas enters the first section of fluidizing device through a first gas inlet at the bottom of the first section of fluidizing device, the iron-containing material and the first reducing gas perform convection heat exchange, the first reducing gas performs dehydration drying treatment and primary preheating pre-reduction treatment on the iron-containing material,

the iron-containing material and the first reducing gas are discharged from a first discharge port at the upper part of the first section of the fluidizing device and enter a first cyclone separator for gas-solid separation to obtain the iron-containing material and the first reducing waste gas after the primary pre-heating pre-reduction treatment, the first reducing waste gas is discharged from an exhaust port at the top of the first cyclone separator and enters a reducing waste gas storage tank,

the pre-reduction degree of the iron-containing material after the primary pre-heating pre-reduction treatment is 0-20%, the temperature of the first reduction waste gas is 150-250 ℃,

the reduction reaction occurring in the first stage fluidising apparatus is: 3Fe₂O₃+CO→CO₂+2Fe₃O₄。

In a preferred embodiment of the iron-containing material pretreatment and composite injection method, the second preheating pre-reduction treatment of the iron-containing material after the first preheating pre-reduction treatment comprises:

the iron-containing material subjected to the primary preheating pre-reduction treatment enters a secondary fluidizing device through a second feed inlet at the lower part of the secondary fluidizing device, second reducing gas enters the secondary fluidizing device through a second gas inlet at the bottom of the secondary fluidizing device, the iron-containing material subjected to the primary preheating pre-reduction treatment and the second reducing gas perform convection heat exchange, and the second reducing gas performs secondary preheating pre-reduction treatment on the iron-containing material subjected to the primary preheating pre-reduction treatment,

the iron-containing material subjected to the primary preheating and pre-reduction treatment and the second reducing gas are discharged from a second discharge port at the upper part of the second-stage fluidizing device and enter a second cyclone separator for gas-solid separation to obtain an iron-containing material subjected to the secondary preheating and pre-reduction treatment and a second reducing waste gas, the second reducing waste gas is used as the first reducing gas to circularly enter the first-stage fluidizing device, the iron-containing material subjected to the secondary preheating and pre-reduction treatment is discharged to a pretreatment sealing tank from a discharge port at the bottom of the second cyclone separator or circularly returns to the second-stage fluidizing device through a material returning device,

the temperature of the iron-containing material after the two-stage preheating and pre-reducing treatment is 600-800 ℃, the pre-reducing degree is 40-70%,

the reactions taking place in the two-stage fluidising apparatus are: 3Fe₂O₃+CO→CO₂+2Fe₃O₄，Fe₃O₄+CO→CO₂+3FeO，FeO+CO→CO₂+Fe。

In a preferred embodiment of the method for pretreating and combined blowing the iron-containing material, in the step (1), the iron-containing material is one or more of industrial solid wastes such as iron concentrate powder, hematite powder, limonite powder, siderite powder, red mud and the like, and iron oxide scale, and the iron content in the iron-containing material is not lower than 30%; the granularity of the crushed and ground iron-containing material is less than 3 mm; the blowing amount of the iron-containing material is 20-280 t/h.

In a preferred embodiment of the iron-containing material pretreatment and composite injection method, the proportion of the pulverized coal in the step (3) is 40-50% of the iron-containing material,

the coal powder is one or more of injection coal, bituminous coal, semicoke, semi-coke and peat, and the carbon content of the coal powder is more than 70%, and the granularity is less than 5 mm; and/or

The proportion of the flux in the step (3) is 13-17% of the iron-containing material,

the flux is alkaline flux, the flux is a mixture of dolomite and lime,

wherein the content of magnesium oxide in the dolomite is not less than 17 percent, the granularity of the dolomite is less than 10mm,

the content of calcium oxide in the lime is not less than 70 percent, the granularity of the lime is less than 3mm,

the proportion of the dolomite to the lime is determined by the binary alkalinity and the quaternary alkalinity of the slag, and the proportion of the lime to the dolomite is as follows:

lime: 1 of dolomite: 1.2 (2R)₄-R₂)～1:2.5(2R₄-R₂)，

Wherein R is₂＝CaO/SiO₂，R₄＝(CaO+MgO)/(SiO₂+Al₂O₃)。

In a preferred embodiment of the method for pretreating and combined injecting iron-containing material, the carrier gas flow rate of the injection carrier gas for iron-containing material in the step (4) is 0-15000Nm³The blowing pressure is 100-500 kPa; and/or

The carrier gas flow of the pulverized coal and flux injection carrier gas in the step (4) is 0-8000Nm³The blowing pressure is 100-500 kPa; and/or

The blowing pressure of the mixed material blowing carrier gas in the step (4) is 100-500 kPa.

According to another aspect of the present application, there is provided a ferrous material pretreatment and composite injection system based on the ferrous material pretreatment and composite injection method of any one of the above, wherein:

the system comprises an iron-containing material pretreatment subsystem and a composite injection subsystem;

the iron-containing material pretreatment subsystem comprises a first-stage fluidizing device, a second-stage fluidizing device, a first cyclone separator and a second cyclone separator,

the first section of the fluidizing device and the second section of the fluidizing device are arranged in series, the first cyclone separator is arranged between the first discharge port of the first section of the fluidizing device and the second feed port of the second section of the fluidizing device, the second cyclone separator is arranged between the second discharge port of the second section of the fluidizing device and the first air inlet of the first section of the fluidizing device,

the first section of fluidizing device adopts one of a circulating fluidizing device, a bubbling fluidizing device and a ring fluidizing device, and/or

The second-stage fluidizing device adopts a circulating fluidizing device;

the composite injection subsystem comprises a hot ore injection device, a coal powder/flux injection device, a composite injection pipeline and a solid spray gun,

the hot ore injection device is connected with the second-stage fluidization device and comprises a hot ore injection tank, a rotary feeder and a first injection pipeline which are sequentially connected,

the pulverized coal/flux injection device comprises a pulverized coal injection device, a flux injection device and a second injection pipeline,

the pulverized coal injection device and the flux injection device are connected to the second injection pipeline together,

the second injection pipeline and the first injection pipeline are converged to form the composite injection pipeline, and the composite injection pipeline is connected with the solid spray gun of the smelting reduction furnace.

In a preferred embodiment of the iron-containing material pretreatment and composite injection system, the composite injection subsystem further comprises:

the flow regulating and pressure regulating valve is arranged in front of the junction of the first injection pipeline and the second injection pipeline and is used for regulating the medium flow in the pipelines and regulating the pressure in a large pressure difference range;

the pneumatic three-way ball valve group is arranged at the junction of pipelines and comprises a pneumatic actuating mechanism and a T-shaped pneumatic three-way ball valve, wherein the pneumatic actuating mechanism is used for receiving a control signal and synchronously driving and controlling the action and the opening and closing state of the three-way ball valve, and the T-shaped pneumatic three-way ball valve is used for controlling the confluence of media in the pipelines;

and the pressure transmitter is arranged in front of the junction of the flow regulating and pressure regulating valve and the first blowing pipeline and the second blowing pipeline and is used for regulating and controlling the blowing pressure of carrier gas in the first blowing pipeline and the second blowing pipeline.

In a preferred embodiment of the iron-containing material pretreatment and composite injection system, the tail end of the composite injection pipeline is separated into a plurality of branch pipes which are respectively connected to each solid injection gun of the smelting reduction furnace; the separating part is provided with a distributor for controlling the flow of the mixed materials of each branch pipe; each branch pipe is provided with an air supplementing device for supplementing carrier gas; the number of the solid spray guns is at least two, and the solid spray guns are provided with anti-blocking pieces for preventing iron slag from blocking the solid spray guns.

In a preferred embodiment of the iron-containing material pretreatment and combined injection system, the iron-containing material pretreatment subsystem further comprises:

the pretreatment sealing tank is connected with the second cyclone separator and the second-section fluidizing device;

the hot ore injection tank is connected with the pretreatment sealing tank, iron-containing materials are conveyed between the pretreatment sealing tank and the hot ore injection tank by means of gravity, a high-temperature dome feeding valve and a rotary exhaust valve are arranged between the pretreatment sealing tank and the hot ore injection tank, and a rotary discharge valve is further arranged at a discharge port of the hot ore injection tank.

Through the technical scheme of the embodiment of the invention, the following beneficial effects can be achieved:

(1) according to the method for preprocessing and composite blowing of the iron-containing material, the iron-containing material is subjected to secondary preheating and prereduction reaction by arranging the first section of fluidizing device and the second section of fluidizing device, the prereduction degree of the iron-containing material is greatly improved, the recycling degree of the first reducing gas and the second reducing gas is high, the energy utilization rate is high, the temperature of the iron-containing material subjected to secondary preheating and prereduction processing reaches 600-800 ℃, and the prereduction degree reaches 40-70%.

(2) According to the method for pretreating and compositely injecting the iron-containing material, the first injection pipeline is arranged to inject the prereduced iron-containing material, the second injection pipeline is arranged to inject the pulverized coal and the flux, and the iron-containing material, the pulverized coal and the flux are premixed in the composite injection pipeline, so that a large amount of sensible heat carried by the prereduced iron-containing material is effectively utilized to preheat the pulverized coal, the surface structure of the preheated pulverized coal is obviously changed, the layered structure and the pore structure are increased, the powdering is developed, the specific surface area is increased, the pulverized coal is looser, the jetting property of the pulverized coal is improved, the pulverized coal is easy to fluidize, and the pneumatic conveying is facilitated; meanwhile, the temperature of the pulverized coal entering the smelting reduction furnace can be increased to more than 200 ℃, the reaction condition in the smelting reduction furnace is optimized, the smelting efficiency of a molten pool is improved, the dynamic condition of the reduction reaction is improved, the forward movement of the pulverized coal in the smelting reduction furnace is promoted, the absorption rate of the pulverized coal in the smelting reduction furnace is increased by more than 10%, the carrying amount of pulverized coal particles in flue gas is reduced, and the carbon content of dust is reduced by more than 20%; in addition, the iron-containing materials, the coal powder and the flux can be fully mixed in the conveying process, the mixing uniformity is improved, the materials can be fully reacted in a melting reduction furnace, and the material loss is reduced.

(3) The application provides a method of iron-containing material preliminary treatment and compound jetting, carry out dehydration drying process and one-level preheating prereduction processing to iron-containing material as first reducing gas in one section fluidizer to one section fluidizer exhaust second reduction waste gas circulation, improved gaseous cyclic utilization degree and energy utilization rate.

(4) According to the method for preprocessing and composite blowing of the iron-containing material, the coal gas generated in the melting reduction furnace is subjected to modification treatment, the obtained modified coal gas is used as the second reducing gas, the reducing gas is provided for the two-section fluidizing device, and the prereduction degree of the iron-containing material is greatly improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

In the drawings:

FIG. 1 is a schematic flow chart illustrating a method for pre-treating and combined blowing iron-containing materials according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram illustrating a pretreatment and combined blowing system for iron-containing materials according to an embodiment of the present invention.

Reference numerals:

1. a ball mill; 2. a belt conveyor; 3. a screw feeder; 4. a ferrous material pretreatment subsystem; 5. a reducing waste gas storage tank; 6. a composite blowing subsystem; 7. a smelting reduction furnace; 8. a gas treatment system; 9. a waste heat power generation system; 41. a first stage of fluidizing means; 42. a second stage fluidizing device; 43. a first cyclone separator; 44. a second cyclone separator; 411. a first air inlet; 412. a first feed port; 413. a first discharge port; 421. a second air inlet; 422. a second feed port; 423. a second discharge port; 424 a third discharge port; 425. a recycle inlet; 426. a material returning device; 427. pretreating a sealing tank; 61. a hot ore injection device; 62. a pulverized coal/flux injection device; 63. a composite blowing pipeline; 64. a solids injection lance; 611. a hot ore injection tank; 612. a first rotary feeder; 613. a first blowing line; 621. a pulverized coal storage tank; 622. a pulverized coal intermediate tank; 623. a pulverized coal injection tank; 624. a flux batching bin; 625. a flux storage tank; 626. a flux intermediate tank; 627. a flux injection tank; 628. a second rotary feeder; 629. a second blowing line; 632. a branch pipe; 81. a vaporization flue; 82. a modified gas conveying pipeline.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

First, the technical concept of the technical solution disclosed in the present invention will be explained. The existing smelting reduction production process directly utilizes the coal gas produced by the smelting reduction furnace, so that the coal gas has high oxidation degree, poor quality and poor reduction capability, and the pre-reduction effect of the iron-containing materials is poor due to the fact that the coal gas is pre-reduced only by a first-stage circulating fluidized bed, and the pre-reduction degree is lower than 20%. Meanwhile, in the traditional iron bath smelting reduction production process, the coal powder and the iron-containing materials are conveyed by two different conveying pipelines, so that the mixing effect of the coal powder and the iron-containing materials is poor, the charging temperature of the coal powder is low, the surface activity is low, and the heat transfer and mass transfer reaction rate of the smelting reduction reaction is seriously influenced. Therefore, the pretreatment stage of the raw fuel becomes a limiting link of the existing smelting reduction process.

In view of the above problems in the prior art, the present invention provides a novel method and system for preprocessing and combined blowing of iron-containing materials. The invention is described below with reference to the accompanying drawings.

The specific scheme is as follows:

according to one aspect of the present application, there is provided a method for pre-treating and combined blowing of iron-containing materials, as shown in fig. 1, the method comprising the steps of:

(2) carrying out secondary preheating pre-reduction treatment on the iron-containing material subjected to the primary preheating pre-reduction treatment, wherein the second reducing gas subjected to the secondary preheating pre-reduction treatment is modified coal gas, the reducing temperature is 800-1000 ℃, the CO content is at least 50%, and the oxidation degree is not more than 20%;

In a preferred embodiment, the dehydration drying treatment and the primary preheating pre-reduction treatment of the iron-containing material comprise the following steps:

the iron-containing material enters the first section of fluidizing device 41 through a first feeding hole 412 at the lower part of the first section of fluidizing device 41, the first reducing gas enters the first section of fluidizing device 41 through a first gas inlet 411 at the bottom of the first section of fluidizing device 41, the iron-containing material and the first reducing gas perform convective heat exchange, the first reducing gas performs dehydration drying treatment and primary preheating pre-reduction treatment on the iron-containing material,

the iron-containing material and the first reducing gas are discharged from a first discharge port 413 at the upper part of the first-stage fluidizing device 41 and enter a first cyclone separator 43 for gas-solid separation to obtain a first-stage pre-heated and pre-reduced iron-containing material and a first reducing waste gas, the first reducing waste gas is discharged from an exhaust port at the top of the first cyclone separator 43 and enters a reducing waste gas storage tank 5,

the reduction reaction occurring in the first stage fluidizing device 41 is: 3Fe₂O₃+CO→CO₂+2Fe₃O₄。

In a preferred embodiment, the second preheating and pre-reducing treatment of the iron-containing material after the first preheating and pre-reducing treatment comprises the following steps:

the iron-containing material after the first-stage preheating pre-reduction treatment enters a second-stage fluidizing device through a second feed port 422 at the lower part of the second-stage fluidizing device 42, second reducing gas enters the second-stage fluidizing device 42 through a second gas inlet 421 at the bottom of the second-stage fluidizing device 42, the iron-containing material after the first-stage preheating pre-reduction treatment and the second reducing gas perform convection heat exchange, and the second reducing gas performs second-stage preheating pre-reduction treatment on the iron-containing material after the first-stage preheating pre-reduction treatment,

the iron-containing material after the first-stage pre-heating pre-reduction treatment and the second reducing gas are discharged from a second discharge port 423 at the upper part of the second-stage fluidizing device 42 and enter a second cyclone separator 44 for gas-solid separation to obtain an iron-containing material after the second-stage pre-heating pre-reduction treatment and a second reducing waste gas, the second reducing waste gas is circulated as the first reducing gas to enter the first-stage fluidizing device 41, the iron-containing material after the second-stage pre-heating pre-reduction treatment is discharged from a discharge port at the bottom of the second cyclone separator 44 to a pre-treatment sealing tank 427 or is circulated back to the second-stage fluidizing device 42 through a material returning device 426,

two-stage fluidization deviceThe reactions taking place in the column 42 are: 3Fe₂O₃+CO→CO₂+2Fe₃O₄，Fe₃O₄+CO→CO₂+3FeO，FeO+CO→CO₂+Fe。

In a preferred embodiment, the iron-containing material in step (1) is one or more of iron concentrate, hematite iron-containing material, limonite iron-containing material, siderite iron-containing material, red mud and other industrial solid wastes, and iron scale, and the iron content in the iron-containing material is not lower than 30%; the granularity of the crushed and ground iron-containing material is less than 3 mm; the blowing amount of the iron-containing material is 20-280 t/h.

In a preferred embodiment, the proportion of the coal powder added in the step (3) is 40-50% of the iron-containing material,

the flux is alkaline flux, the flux is a mixture of dolomite and lime,

lime: 1 of dolomite: 1.2 (2R)₄-R₂)～1:2.5(2R₄-R₂)，

Wherein R is₂＝CaO/SiO₂，R₄＝(CaO+MgO)/(SiO₂+Al₂O₃)。

In a preferred embodiment, the carrier gas blowing amount of the iron-containing material blowing carrier gas in the step (4) is 0 to 15000Nm³H, injection pressure of100-500 kPa; and/or

In order to facilitate understanding of the embodiment of the present invention, the following further describes an exemplary method for pre-treating and blowing combined iron-containing material according to the embodiment of the present invention:

example 1

The embodiment 1 of the application provides a method for preprocessing and compositely blowing iron-containing materials, which comprises the following steps:

(1) after the iron-containing material is crushed and ground by the ball mill 1, the iron-containing material is conveyed to the first section of fluidizing device 41 by the belt conveyor 2 and the screw feeder 3 at a fixed quantitative and fixed speed, the iron-containing material enters the first section of fluidizing device 41 through the first feed inlet 412 at the lower part of the first section of fluidizing device 41, the first reducing gas enters the first section of fluidizing device 41 through the first gas inlet 411 at the bottom of the first section of fluidizing device 41, the iron-containing material and the first reducing gas perform convection heat exchange, the first reducing gas performs dehydration drying treatment and primary preheating pre-reduction treatment on the iron-containing material, the temperature of the first reducing gas in the primary preheating pre-reduction treatment is 500-, obtaining the iron-containing material and the first reducing waste gas after the first-stage preheating and pre-reduction, discharging the iron-containing material after the first-stage preheating and pre-reduction through a discharge hole at the bottom of the first cyclone separator 43, and allowing the iron-containing material to enter the second-stage fluidizing device 42 through a feed inlet at the lower part of the second-stage fluidizing device 42 by means of gravity, and discharging the first reducing waste gas to a reducing waste gas storage tank 5 through an exhaust port at the top of the first cyclone separator 43;

(2) the modified coal gas obtained after the coal gas generated by the smelting reduction furnace 7 is modified is used as a second reducing gas, the iron-containing material subjected to the first-stage preheating pre-reduction treatment enters a second-stage fluidizing device through a second feed inlet 422 at the lower part of the second-stage fluidizing device 42, the second reducing gas enters the second-stage fluidizing device 42 through a second gas inlet 421 at the bottom of the second-stage fluidizing device 42, the iron-containing material subjected to the first-stage preheating pre-reduction treatment and the second reducing gas perform convection heat exchange, the second reducing gas performs the second-stage preheating pre-reduction treatment on the iron-containing material subjected to the first-stage preheating pre-reduction treatment, the iron-containing material and the second reducing gas are discharged through a second discharge outlet 423 at the upper part of the second-stage fluidizing device 42 and enter a second cyclone separator 44, and the iron-containing material and the second reducing gas are subjected to gas-solid separation in the second cyclone separator 44 to obtain the iron-containing material subjected to the second-stage preheating pre-reduction treatment and the second reducing waste gas, the iron-containing material after the secondary preheating pretreatment is discharged to a pretreatment seal tank 427 through a discharge port at the bottom of the second cyclone separator 44 or is circulated back to the second-stage fluidizing device 42 through a return feeder 426, and the second reducing waste gas is discharged through a gas outlet at the top of the second cyclone separator 44 and is circulated into the first-stage fluidizing device 41 as a first reducing gas through a first gas inlet 411 at the upper part of the first-stage fluidizing device 41;

(3) the iron-containing material subjected to the secondary preheating and pre-reduction treatment is discharged to a hot ore injection tank 611 through a pretreatment seal tank 427, and is quantitatively conveyed to a first injection pipeline 613 through a first rotary feeder 612; the pulverized coal passes through a pulverized coal storage tank 621, a pulverized coal intermediate tank 622 and a pulverized coal injection tank 623 in sequence, and then is quantitatively conveyed to a second injection pipeline 629 through a second rotary feeder 628, and the flux passes through a flux proportioning bin 624, a flux storage tank 625, a flux intermediate tank 626 and a flux injection tank 627 in sequence, and then is quantitatively conveyed to the second injection pipeline 629 through the second rotary feeder 628; the first injection pipeline 628 and the second injection pipeline 629 are converged before entering the solid spray gun 64 of the smelting reduction furnace 7 and are combined into a composite injection pipeline 63, so that the pulverized coal, the flux and the iron-containing material after the secondary preheating and pre-reduction treatment are premixed in the composite injection pipeline 63 before being injected into the smelting reduction furnace, and the pulverized coal and the flux are preheated by sensible heat carried by the iron-containing material;

(4) the premixed mixture enters each solid spray gun 64 of the smelting reduction furnace 7 through the composite injection pipeline 63 and the plurality of branch pipes 632, and is mixed and injected into the smelting reduction furnace 7 through each solid spray gun 64, wherein the iron-containing material injection carrier gas, the coal powder and flux injection carrier gas and the mixture injection carrier gas are the first reduction waste gas of the primary preheating pre-reduction treatment.

Specifically, the iron-containing material is one or more of iron concentrate powder, hematite powder, limonite powder, siderite powder, red mud and other industrial solid wastes and iron scale, the iron content in the iron-containing material is not lower than 30%, the particle size of the crushed and ground iron-containing material is less than 3mm, and the injection amount of the iron-containing material is 20-280 t/h.

Specifically, the proportion of the coal powder is 40-50% of the iron-containing material, the coal powder is one or more of injection coal, bituminous coal, semicoke, semi-coke and peat, the carbon content of the coal powder is more than 70%, and the granularity is less than 5 mm.

Specifically, the proportion of the flux is 13-17% of the iron-containing material, the flux is alkaline flux, the flux is a mixture of dolomite and lime, wherein the granularity of the dolomite is less than 10mm, the content of magnesium oxide in the dolomite is not less than 17%, the granularity of the lime is less than 3mm, and the content of calcium oxide in the lime is not less than 70%. The flux is used for removing acid impurities in raw materials to generate a low-melting-point substance Ca₂SiO₄And the viscosity and the melting temperature of the slag are reduced, so that the slag is easy to flow.

Specifically, the mixture of dolomite and lime is premixed in a flux proportioning bin 624 by controlling the binary alkalinity R of slag₂＝CaO/SiO₂With quaternary basicity R of the slag₄＝(CaO+MgO)/(SiO₂+Al₂O₃) Determining the flux ratio; the ratio of lime to dolomite is as follows:

lime: 1 of dolomite: 1.2 (2R)₄-R₂)～1:2.5(2R₄-R₂)。

Specifically, the carrier gas flow rate of the iron-containing material blowing carrier gas is 0-15000Nm³The blowing pressure is 100-500 kPa.

Specifically, the carrier gas flow rate of the pulverized coal and flux injection carrier gas is 0-8000Nm³The blowing pressure is 100-500 kPa.

Specifically, the blowing pressure of the mixed material blowing carrier gas is 100-500 kPa.

The iron-containing material pretreatment method has the advantages of small solid-gas ratio and high heat and mass transfer rates, and can effectively improve the pre-reduction degree of the iron-containing material and the limit value of the preheating temperature; the two-stage preheating pretreatment can realize the graded utilization of energy, and the utilization rate of the energy is improved in limited reaction time. The iron-containing material is subjected to the two-stage pre-heating pre-reduction treatment, so that the speed of the melting reduction reaction is improved; meanwhile, the method is beneficial to further improving the productivity, reducing the coal consumption and improving the energy consumption index of the smelting reduction technology. After two-stage pre-heating and pre-reducing treatment, the temperature and pre-reducing degree of the iron-containing material under different parameters are shown in table 1.

TABLE 1

The composite injection method can efficiently utilize a large amount of sensible heat carried by the preheated iron-containing material, and effectively reduce energy loss in the process of conveying hot ores; the temperature of the pulverized coal is effectively increased, the surface layer and pore structure of the pulverized coal are increased, the pulverization is developed, the specific surface area is increased, the dynamic condition of the smelting reduction reaction is improved, and the reaction rate of a molten pool is increased; the jetting property of the coal powder is improved, and the pneumatic conveying is facilitated; promoting the forward movement of the coal powder in the smelting reduction furnace 7, and improving the absorption rate of the coal powder in the molten iron bath; further reducing the carrying-out quantity of coal powder particles in the flue gas and reducing the carbon content of the dust; meanwhile, the method is beneficial to reducing coal consumption and improving the energy consumption index of the smelting reduction technology. The temperature and the absorption rate of the pulverized coal under different parameters after the treatment by the composite injection method are shown in table 2.

TABLE 2

The iron-containing material pretreatment and composite injection method has high treatment efficiency on the iron-containing materials, short flow and high comprehensive energy utilization rate, can reduce the coal consumption of the iron bath smelting reduction process to below 850kg/t, and increases the thermal efficiency by 3-5%.

According to another aspect of the present application, there is provided a ferrous material pre-treatment and composite injection system based on the ferrous material pre-treatment and composite injection method of any one of the above, as shown in fig. 2, wherein:

the system comprises an iron-containing material pretreatment subsystem 4 and a composite injection subsystem 6;

the iron-containing material pretreatment subsystem 4 comprises a primary fluidizing device 41, a secondary fluidizing device 42, a first cyclone separator 43 and a second cyclone separator 44,

the first-stage fluidizing device 41 and the second-stage fluidizing device 42 are arranged in series, the first cyclone separator 43 is arranged between the first discharge port 413 at the lower part of the first-stage fluidizing device 41 and the second feed port 422 of the second-stage fluidizing device 42, the second cyclone separator 44 is arranged between the second discharge port 423 at the upper part of the second-stage fluidizing device 42 and the first air inlet 411 of the first-stage fluidizing device 41,

the one-section fluidizing device 41 adopts one of a circulating fluidizing device, a bubbling fluidizing device and a ring fluidizing device, and/or

The second-stage fluidizing device 42 adopts a circulating fluidizing device;

the composite injection subsystem 6 comprises a hot ore injection device 61, a coal powder/flux injection device 62, a composite injection pipeline 63 and a solid injection gun 64,

the hot ore injection device 61 is connected with the second section of fluidizing device 42, the hot ore injection device 61 comprises a hot ore injection tank 611, a first rotary feeder 612 and a first injection pipeline 613 which are connected in sequence,

the pulverized coal/flux injection device 62 includes a pulverized coal injection device, a flux injection device, a second injection line 629,

the pulverized coal injection device and the flux injection device are commonly connected to the second injection line 629,

the second injection line 629 and the first injection line 613 are joined to form the composite injection line 63, and the composite injection line 63 is connected to the solids injection lance 64 of the smelting reduction furnace 7.

In a preferred embodiment, the iron-containing material enters the first section of fluidizing device 41 through a first feeding hole 412 at the lower part of the first section of fluidizing device 41, a first reducing gas enters the first section of fluidizing device 41 through a first gas inlet 411 at the bottom of the first section of fluidizing device 41, the iron-containing material is in convective heat exchange with the first reducing gas, the first reducing gas is used for performing dehydration drying treatment and primary preheating pre-reduction treatment on the iron-containing material,

the iron-containing material and the first reducing gas are discharged from a first discharge port 413 at the upper part of the first section of fluidizing device 41 and enter the first cyclone separator 43 for gas-solid separation to obtain a first-stage pre-heated and pre-reduced iron-containing material and a first reducing waste gas, the first reducing waste gas is discharged from an exhaust port at the top of the first cyclone separator 43 and enters a reducing waste gas storage tank 5,

wherein the temperature of the first reducing gas is 500-700 ℃, the CO content is 10-20%, the pre-reduction degree of the iron-containing material after the primary pre-heating pre-reduction treatment is 0-20%, the temperature of the first reducing waste gas is 150-250 ℃,

the reduction reaction occurring in the one-stage fluidizing device 41 is: 3Fe₂O₃+CO→CO₂+2Fe₃O₄。

In a preferred embodiment, the iron-containing material after the primary pre-heating pre-reduction treatment enters the secondary fluidizing device 42 through a second feeding hole 422 at the lower part of the secondary fluidizing device 42, a second reducing gas enters the secondary fluidizing device 42 through a second gas inlet 421 at the bottom of the secondary fluidizing device 42, the iron-containing material after the primary pre-heating pre-reduction treatment and the second reducing gas perform a convection heat exchange, the second reducing gas performs a secondary pre-heating pre-reduction treatment on the iron-containing material after the primary pre-heating pre-reduction treatment,

the iron-containing material subjected to the first-stage preheating and pre-reduction treatment and the second reducing gas are discharged from a second discharge port 423 at the upper part of the second-stage fluidizing device 42 and enter the second cyclone separator 44 for gas-solid separation to obtain an iron-containing material subjected to the second-stage preheating and pre-reduction treatment and a second reducing waste gas, the second reducing waste gas is used as the first reducing gas to circularly enter the first-stage fluidizing device 41, the iron-containing material subjected to the second-stage preheating and pre-reduction treatment is discharged from a discharge port at the bottom of the second cyclone separator 44 to a pretreatment sealing tank 427 or is circularly returned to the second-stage fluidizing device 42 through a material returning device 426,

wherein the second reducing gas is modified gas of the smelting reduction furnace 7, and the flow rate of the second reducing gas is 70000-120000Nm³The flow rate is 6m/s-10m/s, the temperature is 800-1000 ℃, the CO content is more than 50 percent, the oxidation degree is less than 20 percent, the temperature of the iron-containing material after the secondary pre-heating pre-reduction treatment is 600-800 ℃, the pre-reduction degree is 40-70 percent,

the reactions taking place in the secondary fluidizing apparatus 42 are: 3Fe₂O₃+CO→CO₂+2Fe₃O₄，Fe₃O₄+CO→CO₂+3FeO，FeO+CO→CO₂+Fe。

In a preferred embodiment, the composite blowing subsystem 6 further comprises:

a flow-regulating pressure-regulating valve disposed in front of a junction of the first blowing line 613 and the second blowing line 629, the flow-regulating pressure-regulating valve being configured to regulate a flow rate of a medium in the lines and to regulate a pressure in a large differential pressure range;

a pressure transmitter disposed before a junction of the flow-adjusting pressure-regulating valve and the first blowing pipeline 613 and the second blowing pipeline 629, the pressure transmitter being configured to regulate and control blowing pressures of carrier gases in the first blowing pipeline 613 and the second blowing pipeline 629.

In a preferred embodiment, the end of the composite injection line 63 is divided into a plurality of branch pipes 632, which are connected to the respective solids injection lances 64 of the smelting reduction furnace 7; a distributor is arranged at the separation position of the tail end of the composite injection pipeline 63 and is used for controlling the flow of the mixed materials of each branch pipe 632; each branch pipe 632 is provided with an air supplement device for supplementing carrier gas; the number of the solid spray guns 64 is at least two, and anti-blocking pieces are arranged on the solid spray guns and used for preventing the solid spray guns 64 from being blocked by iron slag.

In a preferred embodiment, the iron-bearing material pretreatment subsystem further comprises:

In order to facilitate understanding of the embodiment of the present invention, the following further describes an exemplary iron-containing material pretreatment and composite blowing system according to the embodiment of the present invention:

example 2

Embodiment 2 of the present application provides an iron-containing material pretreatment and composite injection system, which includes an iron-containing material pretreatment subsystem 4 and a composite injection subsystem 6. The iron-containing material pretreatment subsystem 4 comprises a first-stage fluidizing device 41, a second-stage fluidizing device 42, a first cyclone separator 43 and a second cyclone separator 44; the composite injection subsystem 6 comprises a hot ore injection device 61, a coal powder/flux injection device 62, a composite injection pipeline 63 and a solid injection gun 64. Wherein, the first section fluidizing device 41 is connected with the second section fluidizing device 42, a first cyclone separator 43 and a second cyclone separator 44 are arranged between the first section fluidizing device 41 and the second section fluidizing device 42, and the second section fluidizing device 42 is connected with the hot ore injection tank 611. The first blowing line 613 and the second blowing line 629 are merged to form a composite blowing line 63, and the composite blowing line 63 is connected to the solids injection lance 64.

The first-stage fluidizing device 41 is arranged to perform dehydration drying treatment and first-stage preheating pre-reduction treatment on the iron-containing materials, and the second-stage fluidizing device 42 is arranged to perform second-stage preheating pre-reduction treatment on the iron-containing materials, so that the pre-reduction degree of the iron-containing materials is greatly improved; the first injection pipeline 613 is arranged to inject the pre-reduced iron-containing material, and the second injection pipeline 629 is arranged to inject the pulverized coal and the flux, so that the pre-reduced iron-containing material, the pulverized coal and the flux are mixed in the composite injection pipeline 63, thereby efficiently utilizing a large amount of sensible heat carried by the pre-reduced iron-containing material to preheat the pulverized coal, the surface structure of the preheated pulverized coal is obviously changed, the layer structure and the pore structure are increased, the powdering is developed, the specific surface area is increased, the pulverized coal is looser, the injection property of the pulverized coal is improved, the pulverized coal is easy to fluidize, and the pneumatic transmission is facilitated; meanwhile, the temperature of the pulverized coal entering the smelting reduction furnace 7 can be increased to more than 200 ℃, the reaction conditions are optimized, the smelting efficiency of a molten pool is improved, the dynamic conditions of the reduction reaction are improved, the forward movement of the pulverized coal in the smelting reduction furnace 7 in the smelting reaction is promoted, the absorption rate of the pulverized coal in the smelting reduction furnace 7 is increased by more than 10%, the carrying amount of pulverized coal particles in flue gas is reduced, and the carbon content of the fly ash is reduced by more than 20%; in addition, the iron-containing materials, the coal powder and the flux can be fully mixed in the conveying process, so that the mixing uniformity is improved, full reaction in the smelting reduction furnace 7 is facilitated, and the loss of the materials is reduced.

Specifically, the first-stage fluidizing device 41 is one of a circulating fluidizing device, a bubbling fluidizing device and an annular fluidizing device; the secondary fluidizing device 42 employs a circulating fluidizing device.

As an implementation mode, the iron-containing material pretreatment and composite injection system further comprises a grinding device and a conveying device which are connected in sequence, wherein after the iron-containing material is crushed and ground by the grinding device, the iron-containing material is conveyed to a section of fluidizing device 41 by the conveying device at a fixed quantity and a fixed speed to be subjected to dehydration drying treatment and primary preheating pre-reduction treatment.

Specifically, the present embodiment does not limit the type of the grinding device, as long as the crushing treatment of the iron-containing material can be realized. Preferably, the grinding device is a ball mill 1, and the particle size of the iron-containing material after being crushed and ground by the ball mill 1 is less than 3mm, so as to ensure that the iron-containing material can be fully reduced and melted.

Specifically, the type of the conveying device is not limited in this embodiment, as long as quantitative and constant-speed conveying of the iron-containing material can be realized. Preferably, the conveying device comprises a belt conveyor 2 and a screw feeder 3, wherein the belt conveyor 2 is used for controlling the constant-speed conveying of the iron-containing materials and the lifting of the iron-containing materials, and the screw feeder 3 is used for controlling the quantitative conveying of the iron-containing materials. More preferably, the screw feeder 3 is a single screw feeder, and the feeding amount of the iron-containing material is controlled by controlling the rotation speed of the single screw feeder, wherein the feeding amount of the iron-containing material is 20 to 280t/h, and the feeding amount can ensure that the iron-containing material is sufficiently pre-reduced in the first-stage fluidizing device 41 and the second-stage fluidizing device 42 and is sufficiently reduced in the subsequent smelting reduction furnace 7.

Wherein, the discharge gate of ball mill 1 links to each other with the feed chute of band conveyer 2 bottom, and the blown down tank on band conveyer 2 upper portion links to each other with the feed inlet of screw feeder 3, and the discharge gate of screw feeder 3 links to each other with first feed inlet 412 of one section fluidizer 41 lower part.

In one embodiment, a first cyclone 43 is disposed between the first-stage fluidizing device 41 and the second-stage fluidizing device 42, and specifically, the first cyclone 43 is disposed between the first discharge port 413 of the first-stage fluidizing device 41 and the second feed port 422 of the second-stage fluidizing device 42. The iron-containing material enters the first section of fluidizing device 41 through a first feeding hole 412 at the lower part of the first section of fluidizing device 41, the first reducing gas enters the first section of fluidizing device 41 through a gas inlet at the bottom of the first section of fluidizing device 41, the iron-containing material and the first reducing gas perform convection heat exchange, the iron-containing material is subjected to dehydration drying treatment and primary preheating pre-reduction treatment under the action of high temperature and reducing atmosphere, the iron-containing material and the first reducing gas are discharged through a first discharging hole 413 at the upper part of the first section of fluidizing device 41 and enter a first cyclone separator 43 for gas-solid separation, the iron-containing material and the first reducing waste gas after the primary preheating pre-reduction treatment are obtained, and the first reducing waste gas is discharged through a gas outlet at the top of the first cyclone separator 43 and enters.

The iron-containing material enters the first section of fluidizing device 41 through the first feed inlet 412 at the lower part of the first section of fluidizing device 41, the first reducing gas enters the first section of fluidizing device 41 through the first gas inlet 411 at the bottom of the first section of fluidizing device 41, the first reducing gas not only suspends the particles of the iron-containing material to realize effective contact between gas and solid, but also can simultaneously perform reduction reaction with the iron-containing material, in the process, the iron-containing material is in a turbulent state at the bottom of the first section of fluidizing device 41, the mass transfer and heat transfer efficiency between the first reducing gas and the iron-containing material are greatly increased, and the heat transfer coefficient is 350-²K) is more than 10 times of the reaction time in the packed state.

Specifically, the temperature of the first reducing gas is 500-700 ℃, and the CO content is 10-20%; the reduction reaction occurring in the first stage fluidizing device 41 is: 3Fe₂O₃+CO→CO₂+2Fe₃O₄(ii) a The pre-reduction degree of the iron-containing material after the first-stage pre-heating pre-reduction treatment is 0-20%, and the temperature of the first reduction waste gas is 150-250 ℃.

In a first section of fluidizing device 41, the iron-containing material and the first reducing gas carry out convection heat exchange, crystal water in the iron-containing material is completely removed under the high-temperature action of the first reducing gas and is subjected to reduction reaction with the first reducing gas, and part of Fe₂O₃Reduction to Fe₃O₄The pre-reduction degree is 0-20%; the reacted iron-containing material and the first reducing gas are discharged together through a first discharge port 413 at the upper part of the first section of fluidizing device 41 and enter a first cyclone separator 43, the reacted iron-containing material and the first reducing gas are subjected to gas-solid separation in the first cyclone separator 43 to obtain the iron-containing material subjected to primary preheating and pre-reduction treatment and the first reducing waste gas, and the temperature of the first reducing waste gas is 150-250 ℃; the iron-containing material after the first-stage preheating pre-reduction treatment is discharged from a discharge hole at the bottom of the first cyclone separator 43 and enters the second-stage fluidizing device 42 through a second feed hole 422 at the lower part of the second-stage fluidizing device 42, and the first reduction waste gas is exhausted from the top of the first cyclone separator 43The outlet is discharged to a reducing waste gas storage tank 5.

Specifically, the iron-containing material is conveyed from the discharge port of the first cyclone separator 43 to the feed port of the second-stage fluidizing device 42 by means of gravity; preferably, in order to prevent the second reducing gas in the secondary fluidizing device 42 from leaking into the first cyclone 43, a mechanical butterfly valve is provided between the first cyclone 43 and the secondary fluidizing device 42.

Specifically, thermocouples are arranged at the bottom and the top of the first section of fluidizing device 41 to detect the temperature of the first reducing gas when the first reducing gas enters and exits the first section of fluidizing device 41, so that the temperature of the iron-containing material subjected to the primary preheating and pre-reduction treatment is obtained, and the introduction amount of the first reducing gas or the blanking amount of the iron-containing material is regulated and controlled.

Specifically, the operating pressure of the first stage fluidizing device 41 is 70 to 90kPa, preferably 80 kPa.

In one embodiment, a second cyclone 44 is disposed between the second-stage fluidizing device 42 and the first-stage fluidizing device 41, and in particular, the second cyclone 44 is disposed between the first discharge port 423 at the upper part of the second-stage fluidizing device 42 and the first inlet 411 of the first-stage fluidizing device 41. The iron-containing material enters the second-stage fluidizing device 42 through a second feeding hole 422 at the lower part of the second-stage fluidizing device 42, the second reducing gas enters the second-stage fluidizing device 42 through a first gas inlet 421 at the bottom of the second-stage fluidizing device 42, and the iron-containing material and the second reducing gas perform convection heat exchange to perform secondary preheating pre-reduction treatment on the iron-containing material; the iron-containing material and the second reducing gas are discharged from a second discharge port 423 at the upper part of the second-stage fluidizing device 42 and enter a second cyclone separator 44 for gas-solid separation, so that the iron-containing material and the second reducing waste gas after the second-stage pre-heating pre-reduction treatment are obtained.

The iron-containing material enters the second-stage fluidizing device 42 through a second feeding hole 422 at the lower part of the second-stage fluidizing device 42, the second reducing gas enters the second-stage fluidizing device 42 through a second gas inlet 421 at the bottom of the second-stage fluidizing device 42, the second reducing gas not only suspends the particles of the iron-containing material, realizes effective contact between gas and solid, but also can simultaneously perform reduction reaction with the iron-containing material, and in the process, the iron-containing material is in the second-stage fluidizing device 42 is in a turbulent flow state, greatly increases the mass transfer and heat transfer efficiency between the second reducing gas and the iron-containing material, and has a heat transfer coefficient of 350-²K) is more than 10 times of the reaction in a stacking state, and the time of the secondary preheating pre-reduction reaction is greatly shortened.

Specifically, the flow rate of the second reducing gas was 70000-120000Nm³The flow rate is 6m/s-10m/s, the temperature is 800-1000 ℃, the CO content is more than 50 percent, the oxidation degree is not more than 20 percent, and the second reducing gas is the modified coal gas of the smelting reduction furnace 7; the second reducing off-gas enters the first stage fluidizing device 41 as the first reducing gas; the reactions of the secondary preheating pre-reduction treatment are as follows: 3Fe₂O₃+CO→CO₂+2Fe₃O₄，Fe₃O₄+CO→CO₂+3FeO，FeO+CO→CO₂+ Fe; the temperature of the iron-containing material after the two-stage preheating and pre-reducing treatment is 600-800 ℃, and the pre-reducing degree is 40-70%.

The iron-containing material and the second reducing gas are subjected to convection heat exchange and undergo a reduction reaction with the second reducing gas, and the reacted iron-containing material and the second reducing gas are discharged together through a second discharge port 422 at the upper part of the second-stage fluidizing device 42 and enter a second cyclone separator 44; in the second cyclone separator 44, the iron-containing material and the second reducing gas undergo gas-solid separation, the iron-containing material after the secondary pre-heating pre-reduction treatment is discharged through a discharge port at the bottom of the second cyclone separator 44, and the second reducing waste gas is discharged through a discharge port at the top of the second cyclone separator 44 and enters the first section of fluidizing device 41 as the first reducing gas through a first gas inlet 411 at the bottom of the first section of fluidizing device 41.

In one embodiment, the upper portion of the smelting reduction furnace 7 is communicated with the upgraded gas conveying pipe 82 through the vaporizing flue 81, and the upgraded gas conveying pipe 82 is communicated with the second gas inlet 421 at the bottom of the secondary fluidizing device 42, so that the upgraded gas of the smelting reduction furnace 7 is used as the second reducing gas to perform the secondary preheating pre-reduction treatment on the iron-containing material in the secondary fluidizing device 42.

Specifically, the connection position of the vaporization flue 81 and the modified gas conveying pipeline 82 is 5-10m away from the upper end of the vaporization flue 81.

Specifically, the modified gas conveying pipeline 82 is provided with a flow regulating valve and a flow meter, so that the conveying flow rate of the modified gas in the modified gas conveying pipeline 82 is regulated according to the value of the flow meter, and thus the constant conveying flow rate of the modified gas is maintained. Furthermore, one end of the modified gas conveying pipeline 82 close to the second-stage fluidization device 42 is provided with a flow regulating and pressure regulating valve for accurately controlling the flow rate of the modified gas, ensuring that the modified gas enters the second-stage fluidization device 42 at a constant flow rate, and in addition, the adjustment within the working pressure difference range of 1MPa can be realized, and the pressure after the flow regulating and pressure regulating valve is kept stable.

Preferably, in order to ensure that the upgraded gas transportation pipe 82 can withstand the transportation of the high-temperature upgraded gas, refractory bricks are built on the inner surface of the upgraded gas transportation pipe 82.

Specifically, the delivery flow rate of the modified gas delivery pipe 82 accounts for 30-50% of the gas flow rate generated by the smelting reduction furnace 7, and the rest modified gas enters the waste heat power generation system 9 through the vaporization flue 81 to generate power and is converted into power resources for utilization.

In one embodiment, the iron-containing material after the two-stage pre-heating pre-reduction treatment is discharged from the bottom discharge port of the second cyclone 44, passes through the material returning device 426, and is recycled from the material returning device 426 to the second-stage fluidizing device 42 through the recycling material inlet 425. Specifically, the material returning device 426 is a U-shaped structure. By providing the material returning device 426, the iron-containing material in the second-stage fluidizing device 42 can be circularly returned, and a gas seal is provided to prevent the gas from being reversely mixed back to the second-stage fluidizing device 42.

Specifically, the bottom of the material returning device 426 is provided with a circulating hood, the circulating hood is arranged to blow circulating fluidizing gas to the material returning device 426, so that the iron-containing material in the material returning device 426 is fluidized, and the iron-containing material is returned to the two-stage fluidizing device 42 from the material returning device 426, thereby realizing the circulating fluidization two-stage preheating pre-reduction treatment of the iron-containing material. Further, the circulating fluidizing gas injected at the bottom of the material returning device 426 can be one or more of modified coal gas, first reducing waste gas or inert gas, the flow rate of the circulating fluidizing gas accounts for 5-10% of the flow rate of the second reducing gas, and preferably, the circulating fluidizing gas is circulatedThe flow rate of the circulating fluidized gas is 5000-20000Nm³/h。

In one embodiment, a third discharge port 424 is provided at the lower part of the secondary fluidizing device 42, the third discharge port 424 is communicated with a pretreatment seal tank 427, and the pretreatment seal tank 427 is connected to the hot ore blowing device 61. The pre-treatment sealing tank 427 is arranged, so that the iron-containing material subjected to the secondary pre-heating pre-reduction treatment can be temporarily stored, wherein the temperature of the iron-containing material subjected to the secondary pre-heating pre-reduction treatment is 600-800 ℃, and the pre-reduction degree is 40-70%.

Specifically, the second-stage fluidizing device 42 can also be filled with a certain amount of combustion-supporting air through CO and H₂To generate a large amount of heat to raise the temperature of the second reducing gas, thereby raising the reduction temperature in the second-stage fluidizing device 42; furthermore, the combustion air can be oxygen-enriched hot air produced by a hot blast stove, the oxygen-enriched content is 30-40%, and the flow rate of the hot air is controlled to be 0-5000Nm³/h。

Specifically, thermocouples are arranged at the bottom and the top of the second-stage fluidizing device 42 to detect the temperature of the second reducing gas when the second reducing gas enters and exits the second-stage fluidizing device 42, so that the temperature of the iron-containing material subjected to the second-stage pre-heating pre-reduction treatment is obtained, and the introduction amount of the second reducing gas or the blanking amount of the iron-containing material is regulated and controlled.

Specifically, the operating pressure of the secondary fluidizing device 42 is 70 to 90kPa, preferably 80 kPa.

Specifically, the reaction time of the iron-containing material in the secondary fluidizing device 42 is within 10 min.

As an embodiment, the iron-containing material pretreatment and composite injection system further comprises: flow regulating and pressure regulating valve, pneumatic three-way ball valve group and pressure transmitter. The flow regulating and pressure regulating valve is arranged in front of the junction of the first blowing pipeline 613 and the second blowing pipeline 629, and is used for regulating the medium flow in the pipelines and regulating the pressure in a large pressure difference range; the pneumatic three-way ball valve group is arranged at the junction of pipelines and consists of a pneumatic actuating mechanism and a T-shaped pneumatic three-way ball valve, the pneumatic actuating mechanism is used for receiving control signals and synchronously driving and controlling the action and the opening and closing state of the three-way ball valve, and the T-shaped pneumatic three-way ball valve is used for controlling the confluence of media in the pipelines; the pressure transmitter is disposed in front of a junction of the flow-adjusting and pressure-regulating valve and the first blowing pipeline 613 and the second blowing pipeline 629, and is used for adjusting and controlling the blowing pressure of the carrier gas in the first blowing pipeline 613 and the second blowing pipeline 629.

The flow regulating and pressure regulating valve is arranged in front of the junction of the first injection pipeline 613 and the second injection pipeline 629, so that the flow rates of the first injection pipeline 613 and the second injection pipeline 629 are respectively controlled, a constant flow rate is kept, the pressure of the first injection pipeline 613 and the pressure of the second injection pipeline 629 are close to each other when the first injection pipeline 613 and the second injection pipeline 629 are merged, and iron-containing materials in the first injection pipeline 613, coal dust and flux in the second injection pipeline 629 can smoothly enter the composite injection pipeline 63 for mixing.

It will be appreciated that the first and second blowing lines 613, 629 are each provided with a flow regulating pressure regulating valve in front of the junction, and in particular, the flow regulating pressure regulating valves on the first and second blowing lines 613, 629 are each provided at a distance of 2.5-3.5m, preferably 3m, from the junction.

It will be appreciated that pressure transducers are provided on the first and second blowing lines 613, 629, respectively, in front of the junction, at a distance of 1-2m from the junction, respectively.

As an embodiment, the end of the composite injection line 63 is divided into a plurality of branch pipes 632, which are connected to the solid injection lances 64 of the smelting reduction furnace 7; a distributor is arranged at the separation part and is used for controlling the flow of the mixed materials of each branch pipe 632; each branch pipe 632 is provided with an air supplement device for supplementing carrier gas; the number of the solids injection lances 64 is at least two, and the solids injection lances 64 are provided with an anti-blocking member for preventing iron slag from blocking the solids injection lances 64.

Specifically, the composite blowing line 63 is divided into a plurality of branch pipes 632 at 3 to 5m from the end of the composite blowing line 63.

Specifically, the length of the composite injection pipeline 63 is 50-60m, the conveying speed of the mixed materials in the composite injection pipeline 63 is 15-25m/s, and the conveying time of the mixed materials entering the composite injection pipeline 63 to the inlet of the solid spray gun 64 is not less than 3s, so that the iron-containing materials, the coal powder and the fusing agent are fully mixed in the composite injection pipeline 63.

As an implementation mode, the pretreatment sealing tank 427 is directly connected with the hot ore blowing tank 611, the conveying of the iron-containing materials depends on gravity, a high-temperature dome feeding valve and a rotary exhaust valve are arranged between the pretreatment sealing tank 427 and the hot ore blowing tank 611, and a rotary discharge valve is arranged at the discharge port of the hot ore blowing tank 611. By arranging the high-temperature dome feed valve and the rotary exhaust valve between the pretreatment sealing tank 427 and the hot ore injection tank 611, the pressure of the hot ore injection tank 611 is relieved and the exhaust is exhausted before the feeding, so that the leakage of iron-containing material particles is prevented, and the reliable sealing of the hot ore injection tank 611 is ensured. Specifically, a rotary discharge valve is arranged at the discharge port of the hot ore injection tank 611.

Specifically, two first rotary feeders 612 connected in parallel are connected to an outlet of the hot ore injection tank 611, and the iron-containing material subjected to the secondary preheating and pre-reduction treatment is conveyed to a first injection pipeline 613 through the two first rotary feeders 612; the pulverized coal passes through a pulverized coal storage tank 621, a pulverized coal intermediate tank 622 and a pulverized coal injection tank 623 in sequence, and then is conveyed to a second injection pipeline 629 through a second rotary feeder 628, and the flux passes through a flux proportioning bin 624, a flux storage tank 625, a flux intermediate tank 626 and a flux injection tank 627 in sequence, and then is conveyed to the second injection pipeline 629 through the second rotary feeder 628. The iron-containing material in the first injection line 613, the pulverized coal and the flux in the second injection line 629 are premixed in the composite injection line 63 to form a mixed material, the pulverized coal and the flux are preheated by sensible heat brought by the iron-containing material subjected to preheating and pre-reduction treatment, and the mixed material is mixed by the solid spray gun 64 and injected into the smelting reduction furnace 7.

Two first rotary feeders 612 connected in parallel are arranged on a hot ore injection tank 611, a second rotary feeder 628 is respectively arranged behind a coal powder injection tank 623 and a flux injection tank 627 so as to control the feeding amount of each injection tank, accurately control the proportion among iron-containing materials, coal powder and flux, and control the injection precision, wherein the proportion of the coal powder is controlled to be 40% -50% of the iron-containing materials, and the proportion of the flux is controlled to be 13% -17% of the iron-containing materials by regulating and controlling the rotating speeds of the first rotary feeders 612 and the second rotary feeders 628.

As aIn one embodiment, the reducing exhaust gas storage tank 5 is respectively communicated with the first blowing line 613, the second blowing line 629 and the composite blowing line 63, and the blowing carrier gas of the first blowing line 613, the second blowing line 629 and the composite blowing line 63 is the first reducing exhaust gas of the first section of the fluidizing device 41. The arrangement mode can realize the recycling of the first reduction waste gas and the waste gas, and improves the utilization rate of the system energy; and the heat loss of the iron-containing material after preheating is reduced; the furnace charging amount of nitrogen in the system is reduced, so that the generation of nitrogen oxides in the flue gas is reduced; in addition, blowing CO entrained in the carrier gas₂And CO is easily generated by reaction with coal powder, so that the reducing atmosphere is improved, and the dynamic condition of the smelting reduction furnace 7 is improved.

Further, the flow rate of the blowing carrier gas in the first blowing line 613 is 0 to 15000Nm³H; the flow rate of the carrier gas injected into the second injection pipeline 629 is 0-8000Nm³H; the blowing pressure of the blowing carrier gas in the first blowing line 613, the second blowing line 629 and the composite blowing line 63 is all 100-500 kPa. Specifically, the blowing carrier gas lines of the first blowing line 613, the second blowing line 629 and the composite blowing line 63 are all provided with flow regulating valves for controlling the carrier gas flow rate of the first blowing line 613, the second blowing line 629 and the composite blowing line 63.

The iron-containing material pretreatment subsystem has small solid-gas ratio and high heat and mass transfer rate, and can effectively improve the pre-reduction degree of the iron-containing material and the limit value of the preheating temperature; the two-stage preheating pretreatment can realize the graded utilization of energy, and the utilization rate of the energy is improved in limited reaction time. The iron-containing material is subjected to the two-stage pre-heating pre-reduction treatment, so that the speed of the melting reduction reaction is improved; meanwhile, the method is beneficial to further improving the productivity, reducing the coal consumption and improving the energy consumption index of the smelting reduction technology.

The composite injection subsystem can efficiently utilize a large amount of sensible heat carried by preheated iron-containing materials, and effectively reduces energy loss in the process of conveying hot ores; the temperature of the pulverized coal is effectively increased, the surface layer and pore structure of the pulverized coal are increased, the pulverization is developed, the specific surface area is increased, the dynamic condition of the smelting reduction reaction is improved, and the reaction rate of a molten pool is increased; the jetting property of the coal powder is improved, and the pneumatic conveying is facilitated; promoting the forward movement of the coal powder in the smelting reduction furnace 7, and improving the absorption rate of the coal powder in the molten iron bath; further reducing the carrying-out quantity of coal powder particles in the flue gas and reducing the carbon content of the dust; meanwhile, the method is beneficial to reducing coal consumption and improving the energy consumption index of the smelting reduction technology.

The iron-containing material pretreatment and composite injection system has high treatment efficiency on iron-containing materials, short flow and high comprehensive energy utilization rate, can reduce the coal consumption of the iron bath smelting reduction process to below 850kg/t, and increases the thermal efficiency by 3-5%.

The method can be realized by adopting or referring to the prior art in places which are not described in the invention.

While the invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, "above" or "below" a first feature means that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact with each other via another feature therebetween. Also, the first feature being "on," "square," and "over" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The above disclosure provides many different embodiments, or examples, for implementing different features of the invention. The components and arrangements of the specific examples are described above to simplify the present disclosure. Of course, they are merely examples and are not intended to limit the present invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or uses of other materials.

Claims

1. A pretreatment and composite injection method for iron-containing materials is characterized by comprising the following steps:

2. The iron-containing material pretreatment and composite injection method according to claim 1, wherein the dehydration drying treatment and the primary pre-heating pre-reduction treatment of the iron-containing material comprise:

3. The iron-containing material pretreatment and composite injection method according to claim 1, wherein the secondary preheating pre-reduction treatment of the iron-containing material after the primary preheating pre-reduction treatment comprises:

4. The iron-containing material pretreatment and composite injection method of claim 1, wherein:

in the step (1), the iron-containing material is one or more of iron concentrate powder, hematite powder, limonite powder, siderite powder, red mud and other industrial solid wastes and iron scale, and the iron content in the iron-containing material is not lower than 30%; the granularity of the crushed and ground iron-containing material is less than 3 mm; the blowing amount of the iron-containing material is 20-280 t/h.

5. The iron-containing material pretreatment and composite injection method of claim 1, wherein:

the proportion of the coal powder in the step (3) is 40-50% of the iron-containing material,

the flux is alkaline flux, the flux is a mixture of dolomite and lime,

lime: 1 of dolomite: 1.2 (2R)₄-R₂)～1:2.5(2R₄-R₂)，

Wherein R is₂＝CaO/SiO₂，R₄＝(CaO+MgO)/(SiO₂+Al₂O₃)。

6. The iron-containing material pretreatment and composite injection method of claim 1, wherein:

the carrier gas flow of the iron-containing material blowing carrier gas in the step (4) is 0-15000Nm³The blowing pressure is 100-500 kPa; and/or

7. An iron-containing material pretreatment and composite injection system based on the iron-containing material pretreatment and composite injection method according to any one of claims 1 to 6, characterized in that:

The second-stage fluidizing device adopts a circulating fluidizing device;

8. The ferrous material pretreatment and composite injection system of claim 7, wherein the composite injection subsystem further comprises:

9. The ferrous material pretreatment and composite injection system of claim 7, wherein:

the tail end of the composite injection pipeline is separated into a plurality of branch pipes which are respectively connected to each solid spray gun of the smelting reduction furnace; the separating part is provided with a distributor for controlling the flow of the mixed materials of each branch pipe; each branch pipe is provided with an air supplementing device for supplementing carrier gas; the number of the solid spray guns is at least two, and the solid spray guns are provided with anti-blocking pieces for preventing iron slag from blocking the solid spray guns.

10. The ferrous material pretreatment and composite injection system of claim 7, wherein:

the iron-containing material pretreatment subsystem further comprises: