阅读说明：本技术 一种气基直接还原磁选优化铁矿的装置及方法 (Device and method for optimizing iron ore through gas-based direct reduction and magnetic separation ) 是由 张雷 张凯玮 张妍琪 于 2021-07-29 设计创作，主要内容包括：本发明涉及矿物资源节能综合利用技术领域,是一种气基直接还原磁选优化铁矿的装置及方法；装置包括窑体,窑体内由上至下设置有迂回的蛇形烟道,蛇形烟道从上到下分为预热段、加热段、还原段；预热段上方设置有预热料池,预热段的底部连通有落料通道,落料通道穿过加热段和还原段并与加热段和还原段相隔离；落料通道的底端连通有风冷管道,风冷管内设有还原气预热还原装置；风冷管道底部连接有循环研磨系统和磁选优化系统；本发明方法通过原料处理、气基直接还原焙烧、研磨磁选优化得到最终优化产物；本发明解决了现有技术还原效率低、还原加热时间长、加热温度高、保温效果差的问题。(The invention relates to the technical field of energy-saving comprehensive utilization of mineral resources, in particular to a device and a method for optimizing iron ore by gas-based direct reduction and magnetic separation; the device comprises a kiln body, wherein a roundabout snake-shaped flue is arranged in the kiln body from top to bottom, and the snake-shaped flue is divided into a preheating section, a heating section and a reduction section from top to bottom; a preheating material pool is arranged above the preheating section, the bottom of the preheating section is communicated with a blanking channel, and the blanking channel penetrates through and is isolated from the heating section and the reducing section; the bottom end of the blanking channel is communicated with an air cooling pipeline, and a reducing gas preheating and reducing device is arranged in the air cooling pipeline; the bottom of the air cooling pipeline is connected with a circulating grinding system and a magnetic separation optimization system; the method comprises the steps of processing raw materials, directly reducing and roasting in a gas base manner, grinding and magnetic separation optimizing to obtain a final optimized product; the invention solves the problems of low reduction efficiency, long reduction heating time, high heating temperature and poor heat preservation effect in the prior art.)

1. The utility model provides a device of iron ore is optimized in gas base direct reduction magnetic separation, a serial communication port, including the kiln body (1), be provided with circuitous snakelike flue from top to bottom in the kiln body (1), snakelike flue from the top down is divided into the three-layer, does in proper order: a roasting preheating section (5), a roasting heating section (6) and a roasting reduction section (7); the roasting preheating section (5) is connected with a smoke induced air collecting device (601), a preheating material pool (2) is arranged above the roasting preheating section (5), the preheating material pool (2) is communicated with the roasting preheating section (5) through a preheating material pipe (3), the bottom of the roasting preheating section (5) is communicated with a vertical blanking channel (4), and the blanking channel (4) penetrates through the roasting heating section (6) and the roasting reduction section (7) and is isolated from the roasting heating section (6) and the roasting reduction section (7); the roasting reduction section (7) is connected with a burner of a combustion chamber (25); the roasting heating temperature in the roasting reduction section (7) is 960-1030 ℃; the bottom end of the blanking channel (4) is communicated with an air cooling pipe (10) for cooling materials, and the air cooling pipe is internally provided with a reducing gas preheating reduction device with a self-tapping function; the self-tapping reducing device is provided with a reducing gas pipeline; the pressure of the reducing gas in the self-heating reducing device is 600-1200 Pa; an air supply preheater (16) and a cooling hot air collector ⒄ are arranged on the outer wall of the upper end of the air cooling pipe (10); an output lifting device (14) is arranged at the bottom of the air cooling pipe (10), and the output lifting device (14) is sequentially connected with a circulating grinding system and a magnetic separation optimization system; the circulating grinding system comprises a pair roller mill (301), a magnetic separator (302), a screening and extracting device (303), a Raymond mill (304), a centrifugal extracting device (305) and a lifting machine (306) which are connected in sequence; the magnetic separation optimization system comprises a middle magnetic selection device (401).

2. The apparatus for optimizing iron ore by gas-based direct reduction magnetic separation according to claim 1, wherein the reducing gas outlet of the reducing gas preheating and reducing device is provided at the upper end inside the air-cooled tube (10) and toward the blanking passage (4); a heat-preservation reduction connecting section (8) is arranged outside the air cooling pipe (10), the reducing gas enters the air cooling pipe (10) for preheating, and the part of the reducing gas entering the air cooling pipe (10) with the heat-preservation reduction connecting section (8) is directly contacted with the roasting material to absorb the heat energy of the roasting material; the air outlet of the cooling hot air collector ⒄ is connected with the air inlet of the air supply preheater (16), and the air supply preheater (16) is connected with the fire nozzle of the combustion chamber (25).

3. The device for optimizing the iron ore by the gas-based direct reduction and magnetic separation as claimed in claim 1, wherein the temperature of the material is cooled to 45-55 ℃ after passing through the air-cooled pipe (10);

a material guide impeller is arranged below the tail end of the air cooling pipe; a material guide platform water pump is arranged below the material guide impeller; the material guide platform has a silo with a reference after roasting reduction and an output promoting device below the reference.

4. The device for optimizing iron ore by gas-based direct reduction and magnetic separation according to claim 1, characterized in that the reducing gas introduced into the reducing gas preheating and reducing device (9) is H₂ Or CO.

5. The device for optimizing iron ore by gas-based direct reduction and magnetic separation according to claim 1 is characterized by further comprising a raw material processing system, wherein the raw material processing system comprises an iron ore screening and granulating device (101), a flue gas purification and drying device (102) and an iron ore screening and outputting device (103) which are sequentially connected.

6. The device for optimizing iron ore by gas-based direct reduction and magnetic separation according to claim 5 is characterized in that the flue gas induced air collecting device (601) is connected with the flue gas purifying and drying device (102).

7. The device for optimizing iron ore by gas-based direct reduction and magnetic separation according to claim 1, characterized by further comprising an ash and dust removing system, wherein the ash and dust removing system comprises an ash and dust removing device (501) and an electrostatic dust removing device (502) which are connected in sequence; the pair roller mill (301), the screening and extracting device (303) and the middle magnetic concentration device (401) are respectively connected with an ash and dust removing device (501).

8. Method for optimizing iron ore by gas-based direct reduction magnetic separation using the apparatus according to any one of claims 1 to 7, characterized in that it comprises the following steps:

a) raw material treatment: screening, granulating, drying and screening the iron oxide ore to obtain iron ore granular materials with the grain size of 3-40mm, wherein the weight percentage of water is less than 10%;

b) gas-based direct reduction roasting: when the smoke temperature of the roasting reduction section (7) reaches 920-; meanwhile, reducing gas is introduced into the blanking channel (4), and when the flue gas temperature of the roasting reduction section (7) reaches 980 ℃, the blanking speed is v 2; v2 is 5-6 times of v 1; iron ore particle materials are flatly paved and stacked in the preheating material pool (2) to have the thickness of 200-300 mm; the rising speed of the flue gas temperature in the roasting reduction section (7) is less than or equal to 2 ℃/min;

c) the iron ore particle materials after gas-based direct reduction roasting enter an air cooling pipe (10) to be cooled to 45-55 ℃;

d) the cooled materials sequentially pass through a double-roller mill, a magnetic separator, a screening and extracting device, a Raymond mill, a lifter for circular grinding, a medium magnetic selection device and an ash-extracting and dust-removing device to obtain optimized reduced iron fine powder with the particle size of more than 300 meshes; the weight percentage of Fe contained in the optimized reduced iron fine powder is more than 76%.

9. The method for optimizing iron ore by gas-based direct reduction magnetic separation according to claim 8, characterized in that the iron ore particle material is fed by controlling the rotating speed of a guide impeller, the rotating speed of the guide impeller is 4-6 r/h, and the iron ore particle material is conveyed to a double-roll mill.

Technical Field

The invention belongs to the technical field of energy-saving comprehensive utilization and direct reduction of mineral resources, and relates to a gas-based direct reduction roasting kiln and a mineral optimization method; in particular to a device and a method for optimizing iron ore by gas-based direct reduction and magnetic separation.

Background

The direct reduced iron is an optimal and indispensable residual element diluent for smelting high-quality steel; the prior direct reduction process generally requires that the iron-containing Fe of a reduced iron raw material is more than 68.5 percent, the natural raw material is in scarcity, and the natural raw material is difficult to meet the requirement of producing the direct reduced iron raw material in a large scale; secondly, although the energy consumption of the existing gas-based shaft furnace reduction process is 355 kg/ton < 392 kg/ton of the energy consumption of blast furnace ironmaking, the process has the disadvantages of furnace caking, smooth blanking, difficult control of thermal engineering and unstable operation, and becomes the fatal weakness of the existing gas-based shaft furnace reduction process, so that the industrial production and application of the gas-based shaft furnace process are frequently frustrated. In the separation process after the roasting process, incomplete separation and screening treatment often occurs, so that the iron content of the final product is not high.

Disclosure of Invention

The invention overcomes the defects of the prior art and provides a device and a method for optimizing iron ore by gas-based direct reduction and magnetic separation.

In order to achieve the above object, the present invention is achieved by the following technical solutions.

The utility model provides a device of iron ore is optimized in gas base direct reduction magnetic separation, includes the kiln body, the internal snakelike flue that is circuitous that is provided with from top to bottom of kiln, snakelike flue from the top down divide into the three-layer, does in proper order: a roasting preheating section, a roasting heating section and a roasting reduction section; the roasting preheating section is connected with a smoke induced air collecting device, a preheating material pool is arranged above the roasting preheating section, the preheating material pool is communicated with the roasting preheating section through a preheating material pipe, the bottom of the roasting preheating section is communicated with a vertical blanking channel, and the blanking channel penetrates through the roasting heating section and the roasting reduction section and is isolated from the roasting heating section and the roasting reduction section; the roasting reduction section is connected with a burner of a combustion chamber; the roasting heating temperature in the roasting reduction section is 960-1030 ℃; the bottom end of the blanking channel is communicated with an air cooling pipe for cooling materials, and a reducing gas preheating and reducing device is arranged in the air cooling pipe; the reducing gas preheating and reducing device is communicated with a reducing gas pipeline; the pressure of the reducing gas in the reducing gas preheating and reducing device is 600-1200 Pa; an air supply preheater and a cooling hot air collector are arranged on the outer wall of the upper end of the air cooling pipe; the bottom of the air cooling pipe is provided with an output lifting device, and the output lifting device is sequentially connected with a circulating grinding system and a magnetic separation optimization system; the circulating grinding system comprises a pair roller mill, a magnetic separator, a screening and extracting device, a Raymond mill, a centrifugal extracting device and a lifter which are connected in sequence; the magnetic separation optimization system comprises a medium magnetic concentration device.

Further, a reducing gas outlet of the reducing gas preheating and reducing device is arranged at the upper end in the air cooling pipe and faces the blanking channel; the outside of the air cooling pipe is provided with a heat preservation reduction connecting section, the reducing gas enters the air cooling pipe for preheating, and the reducing gas enters the part of the air cooling pipe with the heat preservation reduction connecting section and is directly contacted with the roasting material to absorb the heat energy of the roasting material; and the air outlet of the cooling hot air collector is connected with the air inlet of the air supply preheater, and the air supply preheater is connected with the fire nozzle of the combustion chamber.

Further, the material is cooled to 45-55 ℃ after passing through an air cooling pipe. A material guide impeller is arranged below the tail end of the air cooling pipe; a material guide platform is arranged below the material guide impeller; a roasting reduction rear storage bin is arranged below the material guide platform, and an output lifting device is arranged below the storage bin.

Further, the reducing gas introduced into the reducing gas preheating and reducing device is H₂ Or CO.

Further, still include raw materials processing system, raw materials processing system is including the iron ore screening pelletization device, gas cleaning drying device, the iron ore screening output device that connect gradually.

Furthermore, the smoke induced air collecting device is connected with the smoke purifying and drying device.

The device further comprises an ash and dust removing system, wherein the ash and dust removing system comprises an ash and dust removing device and an electrostatic dust removing device which are sequentially connected; the pair roller mill, the screening and extracting device and the middle magnetic selection device are respectively connected with the ash and dust removing device.

The method for optimizing the iron ore by gas-based direct reduction and magnetic separation comprises the following steps:

a) raw material treatment: screening, granulating, drying and screening the iron oxide ore to obtain iron ore granular materials with the grain size of 3-40mm, wherein the weight percentage of water is less than 10%.

b) Gas-based direct reduction roasting: when the flue gas temperature of the roasting reduction section reaches 920-; meanwhile, reducing gas is introduced into the blanking channel, and when the flue gas temperature of the roasting reduction section reaches 980 ℃, the blanking speed is v 2; v2 is 5-6 times of v 1; iron ore particle materials are flatly paved in a preheating material pool to be stacked with the thickness of 200-300 mm; the rising speed of the flue gas temperature in the roasting reduction section is less than or equal to 2 ℃/min.

c) The iron ore particle materials after gas-based direct reduction roasting enter an air cooling pipe and are cooled to 45-55 ℃.

d) The cooled materials sequentially pass through a double-roller mill, a magnetic separator, a screening and extracting device, a Raymond mill, a lifter for circular grinding, a medium magnetic selection device and an ash-extracting and dust-removing device to obtain optimized reduced iron fine powder with the particle size of more than 300 meshes; the weight percentage of Fe contained in the optimized reduced iron fine powder is more than 76%.

Preferably, the iron ore particle material is fed under the control of the rotating speed of a guide impeller, the rotating speed of the guide impeller is 4-6 r/h, and the iron ore particle material is conveyed to a counter roller mill.

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

1) for the raw material treatment: the raw materials are heated and dried by using the residual heat of the flue gas of the gas-based direct reduction roasting kiln, the smoke discharge temperature of the roasting kiln is 160-200 ℃, the cooling hot air of the roasting material is used as a standby heat source, the raw materials are heated and dried, the production is convenient, and the following favorable conditions are provided for the gas-based direct reduction roasting.

The method comprises the following steps of introducing hot flue gas into a drying device, enabling the flue gas to flow through gaps of raw material particles, enabling micro-dust and harmful substances in the flue gas to be bonded and adsorbed by the raw material particles, incidentally pumping ash to remove the micro-dust and the harmful substances in the screening process, enabling the raw material particles to become flue gas purification filler, enabling the flue gas to be purified and environment-friendly, enabling the temperature of the purified flue gas to be lower than 60 ℃, reducing environmental protection investment, drying the raw material, obviously improving the utilization efficiency of the waste heat of the flue gas, and screening to obtain particle materials.

Secondly, part of impurities (6-10%) in the iron ore are directly removed by dust extraction in the iron ore screening process, so that the production cost consumption is reduced, the roasting heating energy consumption is reduced by more than 6%, and the production process is environment-friendly.

The reduction contact area of iron ore particle gaps is increased, the capacity and the retention space of reducing gas are sufficient, and the reaction time is sufficient;

iron ore particle gaps are convenient for the roasting material to absorb heat energy of flue gas and water to evaporate rapidly and to be discharged along with the flue gas in time, and the consumption of roasting heating natural gas is reduced obviously.

Fifthly, the iron ore particle gaps are favorable for convection reduction reaction, the reduced gas naturally ascends and escapes in time, and the concentration of the reduced gas in the reduction blanking channel is increased in time.

The gaps of the particles are beneficial to the gas after reduction and the excess reducing gas to overflow into the serpentine flue at the reduction section, so that the excess reducing gas and the excess air can be timely and fully combusted in the serpentine flue, and the utilization efficiency of the circulating heat energy is improved; and is also beneficial to the natural formation of gas-based full convection reduction reaction in the blanking channel.

2) For the gas-based direct reduction roasting process: the gas-based direct reduction roasting has the advantages that roasting heating flue gas and blanking reduction are performed in a separate way, so that the situation that the concentration of the reducing gas is insufficient due to dilution of the reducing gas by the flue gas is avoided, the roasting heating combustion is sufficient, and the concentration of the blanking reducing gas is sufficient and excessive is avoided. Blanking particle gaps: the contact surface of reducing gas is enlarged, the holding space is sufficient, the reaction time is sufficient, and the frequency conversion of the reducing time is adjustable.

The air is preheated and supplied by using the cooling heat energy of the roasting material, the temperature of the preheated and supplied air is 320-380 ℃, the heat absorption energy consumption of the supplied air is reduced, the cooling heat energy of the roasting material is recycled, the consumption of heating natural gas is obviously reduced, the heat energy consumption loss in the roasting process is obviously reduced, the cooling efficiency of the roasting material is improved, and the heat energy recycling efficiency is obviously improved. The gas-based direct reduction roasting is carried out, the reduction temperature is controlled at 930 +/-30 ℃, the reduction is carried out at the low temperature, the exhaust gas temperature of the gas-based direct reduction roasting kiln is 160-200 ℃, the raw material is heated and dried by using the waste heat of the flue gas, the temperature of the exhaust gas after heating and drying is less than 60 ℃, and the loss of the exhaust heat energy is obviously reduced. The gas-based direct reduction roasting kiln has good heat preservation effect, the external temperature of the kiln is close to normal temperature, and the heat dissipation loss is greatly reduced. The gas-based direct reduction roasting is carried out, and the heating flue gas naturally heats up layer by layer along the serpentine flue, so that the power consumption of flue gas induced air is very low. The roasting material is under the gravity, so the material guiding impeller controls the blanking power consumption to be extremely low at 4-6 revolutions per hour.

In the roasting reduction process, gas-based reduction gas enters the cooling pipe from the middle upper part of the air cooling pipe, the reduction gas naturally and slowly ascends along with the preheating of roasting particle gaps (the preheating temperature of the reduction gas is more than 850 ℃) to naturally form gas-based convection reduction reaction in the blanking channel; and the reduced gas and the excessive reducing gas overflow into the serpentine flue from the overflow port. Overflowing the excessive reducing gas into a snake-shaped flue: the excess reducing gas and the excess air in the serpentine flue are timely and fully combusted, the investment and the cost of flue gas treatment equipment are saved, the energy-saving efficiency of flue gas heat energy recycling is obviously improved, the energy consumption of roasting and heating is obviously reduced, the flue gas emission is reduced, and the environment is protected.

The two side walls of the S-shaped flue are uniformly heated, the flue gas containing space of the S-shaped flue is large, heat storage and energy storage are realized, the instantaneous heating temperature is too high, and the effect of timely and fully relieving is achieved.

The roasting heating flue gas slowly goes upwards from the lower layer-by-layer snake-shaped natural heating along the reduction section snake-shaped flue, the heating section snake-shaped flue and the preheating section snake-shaped flue, and the heat exchange efficiency is obviously improved. The roasting material falls into the blanking channel of the preheating section, the roasting material is in direct contact with the heating flue gas, the roasting material fully absorbs the heat energy of the flue gas, and the moisture is quickly evaporated and discharged along with the flue gas in time.

The roasting material falls into the material falling channel of the reduction section, the reduced gas and the excess reducing gas overflow into the serpentine flue from the overflow port of the reduction section, the excess reducing gas and the excess air in the serpentine flue are timely and fully combusted, the environment-friendly investment is reduced, the pollution emission is reduced, the excess air is timely and adjustable by utilizing the preheated hot air, and the timely cyclic utilization efficiency of heat energy is obviously improved.

The roasting material falls into a material falling channel of the roasting heat-preservation connecting section, the reduction temperature is kept well, the concentration of the reduction gas is sufficient, the reduction time is sufficient, and the roasting convection reduction atmosphere is more sufficient and reliable. The roasting material falls into an air-cooled square tube, the roasting material is cooled and slowly descends under the control of the rotating speed of a material guide impeller of 4-6 revolutions per hour, and the power consumption of the rotating power of the material guide impeller is extremely low; the roasting material is naturally air-cooled to about 50 ℃ in the air-cooled square tube, so that the secondary oxidation of the roasting material is avoided, no water is used for magnetic separation optimization, the water resource consumption is saved, and the regional adaptability is strong.

The method comprises the following steps of (1) gas-based direct reduction roasting, wherein a partition plate is arranged between a roasting reduction section and a roasting heating section in a flue, and a flange is arranged at the tail end of the partition plate towards the roasting reduction section; the partition plate is arranged between the roasting heating section and the roasting preheating section, and flanges are symmetrically arranged in the roasting heating section at the tail end of the partition plate and the roasting preheating section, so that the temperature of each section is effectively guaranteed.

The gas-based direct reduction roasting is characterized in that the temperature, the concentration of reduction gas and the reduction time required in the reduction roasting process are respectively controlled, the mutual influence among various control parameters is relatively weak, the iron ore can be highly naturally coordinated and controlled in a required full convection reduction atmosphere, and the thermal control is accurate and easy to control. The gas-based direct reduction roasting process has the advantages that internal and external preheating and heating are carried out in the process of gas-based direct reduction roasting, heat energy is recycled, the consumption of roasting and heating natural gas is obviously reduced, and the problems of low reduction efficiency, long reduction and heating time, high heating temperature and poor heat preservation effect in the prior art are solved; because the reduction temperature is controlled at 930 +/-30 ℃ for low-temperature reduction, the roasted material is extremely easy to be ground, and convenience is provided for further magnetic separation optimization.

3) For a recirculating grinding system: tests show that the gas-based direct reduction roasting material is extremely easy to grind, and secondly, after the iron ore is subjected to gas-based low-temperature direct reduction roasting, the reduced iron is hard, most impurities are soft, the specific gravity of the impurity dust is relatively small, the reduced material grinding impurity dust is timely subjected to magnetic separation and ash extraction removal, the grinding power consumption is extremely low, and convenience is provided for further magnetic separation optimization; the roasted reducing material is sequentially subjected to a roller mill, a magnetic separator, a screening and pumping device, a Raymond mill, a centrifugal pumping device, a lifter and circulating grinding, magnetic separation, ash pumping and dust removal to obtain the reducing material with the particle size of more than 300 meshes.

4) Magnetic separation optimizing system: the reduced materials with the grain size of more than 300 meshes are refined by a medium-magnetic refining device and separated to obtain the optimized reduced iron fine powder product with the iron content of more than 76 percent, thereby solving the problem of the rare shortage of the reduced iron raw materials in the world in nature and providing convenience for further producing the reduced iron.

5) Ash and dust removing separation system: the ash removal and dust removal device not only removes ash and dust, but also provides a negative pressure favorable condition for the magnetic separation optimization process, and the electrostatic dust removal further improves the dust removal efficiency.

6) Flue gas waste heat utilization system: namely, the flue gas is collected and induced air device, the flue gas is introduced into the flue gas purification and drying device, the flue gas is purified, the iron ore raw material is dried, the iron ore particles become the purification filler, the flue gas waste heat is efficiently recycled, and the emission is reduced, so that the environment is protected.

The reduced iron concentrate powder prepared by the method has the grade of Fe larger than 76 percent, obvious effect of removing harmful impurities, sulfur removal efficiency larger than 60 percent and phosphorus removal efficiency larger than 65 percent. The method has low requirement on the iron oxide ore, and solves the problem of scarcity of reduced iron raw materials as long as the iron content is more than 38 percent and the raw materials have high relative density and good economic benefit.

Compared with other existing processes at home and abroad, the process flow is short, flexible and practical, energy-saving and efficient, free of adhesion and caking, large in treatment capacity, stable in product quality, small in relative investment, quick in effect, capable of being developed while producing, finally forming intensive large-scale production, capable of realizing rolling explosive growth development and the like; therefore, the process is a high-quality, low-consumption, energy-saving and efficient clean, energy-saving, direct reduction, green development and innovation process, has wide market development prospect, is easy to popularize, has huge energy-saving development potential due to the fact that the comprehensive energy consumption is less than one half of that of other processes, particularly improves the quality structure and energy structure of steel products, breaks away from the constraint of coking coal resources on the production and development of steel, and has more advantages from the source of energy conservation and emission reduction.

Drawings

FIG. 1 is a main sectional view showing the structure of a gas-based direct reduction roasting kiln of the present invention.

FIG. 2 is a schematic sectional view taken along line A-A in FIG. 1.

FIG. 3 is a schematic connection diagram of the device for optimizing iron ore by gas-based direct reduction and magnetic separation.

In the figure: the device comprises a kiln body 1, a preheating material pool 2, a preheating material pipe 3, a blanking channel 4, a roasting preheating section 5, a roasting heating section 6, a roasting reduction section 7, a heat preservation reduction connecting section 8, a reducing gas preheating reduction device 9, an air cooling pipe 10, a guide impeller 11, a guide platform 12, a storage bin 13, an output lifting device 14, a heat preservation sealing gap 15, an air supply preheater 16, a cooling hot air collector 17, a support beam 18, a backing ring 19, a support column 20, a distributing machine 21, a serpentine flue 22, a temperature monitoring device 23, a fire observation hole 24, a combustion chamber 25 and a reducing gas overflow port 26.

101 is an iron ore screening granulator, 102 is a flue gas purification and drying device, and 103 is an iron ore screening output device;

301 is a pair roller mill, 302 is a magnetic separator, 303 is a screening and extracting device, 304 is a Raymond mill, 305 is a centrifugal extracting device, and 306 is a hoister;

401 is a middle magnetic concentration device, 402 is optimized iron fine powder, 501 is an ash and dust removing device, 502 is an electrostatic dust removing device, and 601 is a smoke induced air collecting device.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solutions of the present invention are described in detail below with reference to the embodiments and the drawings, but the scope of protection is not limited thereto.

As shown in fig. 3, the device for optimizing iron ore by gas-based direct reduction and magnetic separation mainly comprises 6 parts: the system comprises a raw material processing system, a gas-based direct reduction roasting kiln, a circulating grinding system, a magnetic separation optimization system, an ash and dust removing system and a flue gas waste heat utilization system.

The raw material processing system comprises an iron ore screening granulator 101, a flue gas purification and drying device 102 and an iron ore screening and outputting device 103 which are connected in sequence.

Gas-based direct reduction roasting kiln: as shown in fig. 1-2, wherein: kiln body 1 is hollow shell, and the internal brickwork of kiln 1 from top to bottom has circuitous snakelike flue 22, and the heating of the wide 24 centimetre both sides walls of snakelike flue is even, and snakelike flue from the top down divide into the three-layer, does in proper order: the device comprises a roasting preheating section 5, a roasting heating section 6 and a roasting reduction section 7, wherein a preheating material pool 2 is concavely arranged in the middle of the top wall of a kiln body 1 towards the inner side of the kiln body 1, a distributing machine 21 is arranged above the preheating material pool 2, and materials passing through a raw material processing system are conveyed to the preheating material pool 2 through the distributing machine 21; a plurality of preheating pipes 3 are uniformly arranged on the bottom surface of the preheating material pool 2, the preheating material pool 2 is communicated with the roasting preheating section 5 through the preheating pipes 3, the bottom of the roasting preheating section 5 is communicated with a vertical blanking channel 4, and the blanking channel 4 penetrates through the roasting heating section 6, the roasting reduction section 7 and the heat-preservation reduction connecting section 8 and is isolated from the roasting heating section 6 and the roasting reduction section 7; the bottom end of the blanking channel 4 is communicated with an air cooling pipeline 10 for cooling materials, and the middle upper part of the air cooling pipeline 10 is provided with a reducing gas preheating and reducing device 9 and is communicated with a reducing gas pipeline; the reducing gas outlet of the reducing gas preheating and reducing device 9 is arranged at the upper end in the air cooling pipe 10 and faces the blanking channel 4. The reducing gas preheating and reducing device 9 is used for providing reducing gas for the blanking channel 4; the air supply preheater 16 is arranged on the outer wall of the air cooling pipe 10 and used for preheating air supply for the combustion chamber 25, and the outer wall of the air cooling pipe 10 is also provided with a cooling hot air collector 17. The side wall of the upper part of the blanking channel 4 positioned in the roasting reduction section 7 is uniformly provided with a reducing gas overflow port 26. The roasting reduction section 7 is connected with a burner of a combustion chamber 25. The side wall of the roasting reduction section 7 is provided with a fire observation hole 24, and a temperature monitoring device 23 is arranged above the fire observation hole 24.

And a partition plate is arranged between the roasting reduction section 7 and the roasting heating section 6, and a flange is arranged at the tail end of the partition plate towards the roasting reduction section 7. And a partition plate is arranged between the roasting heating section 6 and the roasting preheating section 5, and flanges are symmetrically arranged in the roasting heating section 6 and the roasting preheating section 5 at the tail end of the partition plate. And communicated heat-preservation sealing gaps 15 are arranged between the side wall of the kiln body 1 and the preheating material pool 2 and between the side wall of the kiln body 1 and the roasting system. A heat-preservation reduction connecting section 8 is supported below the roasting reduction section 7, a supporting beam 18 is arranged between the lower part of the heat-preservation reduction connecting section 8 and the bottom surface of the kiln body 1, a backing ring 19 is arranged below the bottom surface of the kiln body 1, and a supporting column 20 is arranged between the backing ring 19 and the ground.

A material guiding impeller 11 is arranged below the tail end of the air cooling pipe 10, a material guiding platform 12 is arranged below the material guiding impeller 11, a storage bin 13 is arranged below the material guiding platform 12, and an output lifting device 14 is arranged below the storage bin 13.

The material delivered from the kiln body 1 is delivered by the output lifting device 14 to the circulating grinding system: the circulating grinding system comprises a counter-roll mill 301, a magnetic separator 302, a screening and extracting device 303, a Raymond mill 304, a centrifugal extracting device 305 and a lifting machine 306 which are connected in sequence. For the roller mill 301: and circularly grinding the roll mill to grind the reducing material to more than 200 meshes. A magnetic separator 302: impurities are separated in time by the magnetic separator 302, so that the processing energy consumption is reduced. Screening extraction device 303: circulating screening and pumping to separate reducing materials with more than 200 meshes in time. Raymond mill 304: grinding the reduced material with more than 200 meshes to more than 300 meshes by a Raymond mill in a circulating way. Centrifugal pumping device 305: and (3) timely extracting the 300-mesh reducing material, and timely removing dust. Hoisting machine 306: the lifter 306 circularly lifts to facilitate the circular grinding and magnetic separation ash pumping production.

The material sent out from the centrifugal pumping device 305 enters a magnetic separation optimization system: the magnetic separation optimization system comprises a medium magnetic separation selection device 401, and the obtained reduced material with the granularity of more than 300 meshes is selected by the medium magnetic separation device 401 to obtain the optimized iron concentrate powder 402 with Fe being more than 76%. And after the optimized fine iron powder 402 is inspected to be qualified, bagging or briquetting and warehousing according to the requirements of customers.

The double-roller mill 301, the screening and extracting device 303 and the middle magnetic concentration device 401 are respectively connected with an ash and dust removing device 501, and the ash and dust removing device 501 is connected with an electrostatic dust removing device 502. The ash and dust removing device 501 not only removes ash and dust but also provides system negative pressure for the magnetic separation optimization process. The electrostatic precipitator 502 further improves the dust removal efficiency.

The flue gas induced air collecting device 601 collects flue gas generated by gas-based direct reduction roasting, and introduces the flue gas into the flue gas purification and drying device 102 to heat and dry the raw materials.

A method for optimizing iron ore by gas-based direct reduction and magnetic separation comprises the following steps:

filling iron ore particle materials of 3-40mm into a blanking channel 4 of a roasting kiln through a distributing machine 21, and tiling and stacking the iron ore particle materials in a preheating material pool 2 to achieve the thickness of 200-300 mm; starting a burner of the combustion chamber 25 for heating, so that the temperature rise speed of the flue gas is less than or equal to 2 ℃/min, monitoring the temperature of each section in the serpentine flue through a temperature monitoring device 23, when the temperature of the flue gas in the reduction section flue reaches 900 ℃, slowly starting the material guide impeller 11 to start feeding at 1 r/h, simultaneously slowly starting an adjusting main valve of the reducing gas preheating reduction device 9 to start gas supply, and adjusting the pressure of the reducing gas to a sufficient reduction range required by the roasted material along with the temperature rise, wherein the pressure is adjusted to be within the range: the air pressure of the reducing gas is higher than the marked air pressure of 600-1200 Pa; the feeding speed is adjusted to about 5 revolutions per hour when the temperature of the snakelike flue of the reduction section rises to 980 ℃ along with the rising speed of the reduction temperature of the roasted material.

The roasting material falls into a preheating section: the roasting preheating section 5 heats flue gas and is directly contacted with the reduction blanking, the roasting material fully absorbs the heat energy of the flue gas, water is quickly evaporated and is timely discharged along with the flue gas, and the flue gas temperature is 160-200 ℃.

Thirdly, the roasting material falls into the heating section: the heating section blanking channel 4 is separated from the roasting heating section 6, and the roasted material is heated and slowly descends along with the material guiding rotation speed.

Fourthly, the roasted material falls into a reduction section: the reduction section blanking channel 4 is separated from the roasting reduction section 7, so that the dilution of the reducing gas by the flue gas is avoided, the reducing gas flows upward along with the convective reduction heating of gaps of roasting material particles, the reduced gas and the excess reducing gas overflow into the serpentine flue from the overflow port, the excess reducing gas and the excess air in the serpentine flue are timely and fully combusted, the excess reducing gas treatment equipment is omitted, the cost and the environment are friendly, the energy-saving recycling efficiency of the excess reducing gas is obviously improved, and the concentration of the reducing gas can be timely adjusted according to the requirement of full reduction on air pressure. The heating smoke slowly and naturally goes upwards to heat layer by layer along with the serpentine flue; the heating and combustion is sufficient, the heating temperature is timely adjustable by utilizing preheating and air supply, the reduction temperature is controlled to be 930 +/-30 ℃, the speed of the roasted material naturally falls along with the rotating speed of the material guide impeller, the speed is adjustable, and the convection reduction time is sufficient.

The roasting material falls into a heat preservation reduction connecting section: the reduction temperature is kept well, the reduction gas is sufficient, the roasted material passes through the reduction section and the heat preservation section for more than 6 hours at 5-6 revolutions per hour, the reduction time required by the roasted material is 3 hours, the reduction time is sufficient, and the roasting convection reduction atmosphere is sufficient.

Sixthly, reducing gas enters from the middle upper part of the cooling pipeline 10, is slowly preheated along with iron ore particle gaps, is reduced and ascends, and naturally forms gas-based convection reduction reaction in the blanking channel. Natural air cooling is adopted to avoid reoxidation risk, a preheater 16 and a cooling hot air collector 17 are arranged on the upper portion of the outer wall of the air cooling pipe, the temperature of hot air is further improved by using the cooling heat energy of the roasting material, and the temperature of preheating air supply is generally 320-380 ℃, so that the self heat absorption energy consumption of hot air is obviously reduced, experiments show that the consumption of heating natural gas is relatively reduced by more than 18%, the roasting material is cooled to about 50 ℃, the cooling efficiency is improved, and the heat energy recycling efficiency in the roasting reduction process is obviously improved.

And after air cooling, the roasted material passes through the material guide platform 12 and falls into a roasting bin 13 under the control of the material guide impeller 11. The calcine is fed to the circulating grinding system via an output elevator 14. The gas-based direct reduction roasting not only forms a sufficient and efficient convection reduction reaction, but also ensures that the low-temperature reduction roasting material is extremely easy to mill and the impurities are extremely easy to separate, thereby providing convenience for further magnetic separation optimization.

Specifically, the method comprises the following steps:

example 1

Certain iron oxide ores contain iron Fe38.85%. The method comprises the following steps:

firstly, raw material treatment: and (3) crushing, screening, granulating, drying and screening the iron oxide ore containing 38.85 wt% of Fe to obtain iron ore particles of 3-40mm, wherein the weight percentage of water is less than 10%.

② gas-based direct reduction roasting: roasting the iron ore particle materials of 3-40mm in a gas-based direct reduction roasting test kiln, controlling the gas pressure of gas-based reduction gas hydrogen to be 1000Pa higher than the labeled gas pressure, controlling the reduction temperature of a reduction section to be about 930 ℃, and discharging at the rotating speed of a guide impeller of 5 r/h to obtain roasted and reduced materials.

Thirdly, circularly grinding and magnetic separation: and (3) circularly grinding, magnetically separating, ash pumping and dedusting the obtained roasted and reduced material by a double-roller mill, a magnetic separator, a screening and pumping device, a Raymond mill, a centrifugal pumping device and a lifter in sequence to obtain the reduced material with the granularity of more than 300 meshes.

Magnetic separation optimization: and (3) concentrating the obtained reduced material with more than 300 meshes by a medium-magnetic concentration device to obtain optimized reduced iron fine powder: fe78.35%, P0.014% and S0.017% with other impurity content meeting the requirement of reduced iron production.

Energy consumption of the ton ore: the standard coal consumption for roasting and heating is 78.16 kg/ton ore, and the electricity consumption for magnetic separation is optimized to be 67 degrees/ton ore.

Example 2

Some iron oxide ores contain iron Fe48.63%. The method comprises the following steps:

firstly, raw material treatment: and (3) crushing, screening, granulating, drying and screening Fe48.63% iron oxide ore to obtain iron ore particles of 3-40mm, wherein the weight percentage of water is less than 10%.

② gas-based direct reduction roasting: roasting the iron ore particle materials of 3-40mm in a gas-based direct reduction roasting test kiln, controlling the gas pressure of gas-based reduction gas to be higher than the marked gas pressure by 1200Pa, controlling the reduction temperature of a reduction section to be about 930 ℃, and discharging at the rotating speed of a guide impeller of 5 r/h to obtain roasted and reduced materials.

Thirdly, circularly grinding and magnetic separation: and (3) circularly grinding, magnetically separating, ash pumping and dedusting the obtained roasted and reduced material by a double-roller mill, a magnetic separator, a screening and pumping device, a Raymond mill, a centrifugal pumping device and a lifter in sequence to obtain the reduced material with the granularity of more than 300 meshes.

Magnetic separation optimization: and (3) concentrating the obtained reduced material with more than 300 meshes by a medium-magnetic concentration device to obtain optimized reduced iron fine powder: fe80.46%, P0.014% and S0.016% and the content of other impurities meets the production requirement of reduced iron.

Energy consumption of the ton ore: the standard coal consumption for roasting and heating is 76.36 kg/ton ore, and the electricity consumption for magnetic separation is optimized to be 63 degrees/ton ore.

While the invention has been described in further detail with reference to specific preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.