CN110530160B - Microwave continuous suspension magnetizing roasting system for treating iron ore - Google Patents
Microwave continuous suspension magnetizing roasting system for treating iron ore Download PDFInfo
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Abstract
A microwave continuous suspension magnetizing roasting system for treating iron ore is characterized in that a discharge hole at the bottom of a feeding bin is communicated with a feed inlet of a pretreatment fluidizer, a microwave cavity is sleeved outside the pretreatment fluidizer, and a pretreatment baffle is arranged inside the pretreatment fluidizer to divide the interior of the pretreatment fluidizer into a pretreatment feed chamber and a pretreatment discharge chamber; a reduction baffle is arranged in the reduction fluidizer to divide the interior of the reduction fluidizer into a reduction feeding chamber and a reduction discharging chamber, and a discharge hole of the reduction fluidizer is communicated with a feed hole of the cooler; the microwave cavity is assembled with the microwave generating device. The system of the invention has high heating efficiency; the continuous operation of microwave fluidization magnetizing roasting can be realized, and the continuous and safe operation of the system is facilitated; can effectively pre-oxidize the material by heating, and is beneficial to the efficient implementation of the subsequent magnetizing roasting.
Description
Technical Field
The invention belongs to the technical field of mineral processing, and particularly relates to a microwave continuous suspension magnetizing roasting system for treating iron ore.
Background
The iron ore resource is a solid foundation for national economy and social development, and has irreplaceable effects on supporting the sustainable development of the national economy and guaranteeing the safe operation of the social citizens.
In recent years, around the high-efficiency development and utilization of complex refractory iron ores, a large number of basic research and technical development works are developed by a plurality of research units at home and abroad, wherein the effect of the process of concentration and metallurgy combination, namely magnetizing roasting-magnetic separation, is most remarkable, and the magnetizing roasting-magnetic separation refers to converting weak-magnetic iron minerals such as hematite, siderite, limonite and the like into strong-magnetic magnetite or maghemite through chemical reaction and then performing magnetic separation by utilizing the magnetic difference among the minerals; the magnetizing roasting mode comprises shaft furnace roasting, rotary kiln roasting, fluidized roasting and the like; in recent years, due to the characteristics of good separation effect, sufficient gas-solid contact, rapid reaction, high production capacity and the like, the fluidization magnetization roasting technology for treating weak magnetic iron ores such as hematite, siderite, limonite and the like has great advantages; fluidized magnetic roasting is a process of heating powder materials to a certain temperature in a suspension state, introducing reducing gas to reduce weak magnetic iron ores such as hematite, siderite, limonite and the like in the materials into strong magnetic iron minerals, and magnetically separating the roasted materials to obtain high-quality iron ore concentrates; therefore, a great deal of research is carried out by a plurality of research units in China on fluidization magnetization roasting technology and equipment, a new concept of flash magnetization roasting is provided by the rest of Hospital and scientific research teams thereof, basic theoretical researches such as flash magnetization roasting thermodynamics, dynamics and fluidization characteristics are carried out, and flash magnetization roasting complete technology and equipment are developed. The process engineering research institute of the Chinese academy of sciences develops a complete set of new technology and equipment for fluidizing and magnetizing roasting of complex refractory iron ores, and builds a 10 ten thousand/a refractory iron ore fluidizing and magnetizing roasting demonstration project in Yunnan Qujing, and the process engineering works continuously and stably. The northeast university provides a new idea of 'pre-oxidation, regenerative reduction and reoxidation' suspension magnetization roasting of complex refractory iron ore, develops a suspension magnetization roasting laboratory and pilot plant equipment, and performs suspension magnetization roasting tests on various weak magnetic iron ore resources such as wine steel, saddle steel, mountain steel, medium steel and the like to obtain good technical indexes.
The microwave refers to electromagnetic wave with the frequency of 300 MHz-300 GHz and the wavelength of 1 mm-1 m, and can permeate into the mineral molecules, so that heating starts to occur from the interior of the molecules, heat conduction is not needed, the heat efficiency is high, and the energy consumption is low; secondly, different minerals coexisting in the same ore can show different temperature rise changes, so that the softening of the joint surface is intensified; therefore, the microwave roasting has the characteristics of rapid heating, selective heating, low energy consumption, enhancement of mineral monomer dissociation degree and grindability and the like, and in the application process of metallurgical engineering, compared with the traditional roasting, the microwave roasting has great advantages, the microwave roasting rate is 3.97-7.15 times higher than the traditional roasting rate, and the unique selective heating advantage of microwaves enables the useful minerals and gangue minerals to have great differences in wave-absorbing characteristics, so that thermal stress is generated on a mineral junction surface to form cracks and cracks, the mineral monomer dissociation degree and grindability can be remarkably improved, more energy is saved, consumption is reduced, and the sorting effect is more remarkable; numerous expert scholars develop a great deal of basic research aiming at microwave roasting, the main research direction focuses on the aspects of mineral microwave pretreatment, mineral wave absorbing property, microwave grinding, static carbon thermal reduction microwave roasting and the like, and the results show that the microwave roasting has greater advantages compared with the traditional roasting; however, the microwave is absorbed by the medium during propagation to cause loss and attenuation, and the microwave penetration is limited, and the microwave and the material are limited to interact in a certain depth range, which is called the microwave penetration depth. The microwave penetration depth is used for representing the degree of penetration of the microwave into the material, which directly influences the heating uniformity and the heating effect of the material; due to the influence of the penetration depth of the microwaves, the static carbothermic reduction microwave magnetization roasting method is difficult to realize the high-efficiency comprehensive utilization of the complex refractory iron ores.
At present, a device and a method for efficiently and comprehensively treating complex refractory iron ores are developed, so that energy conservation and consumption reduction are realized, selective rapid heating is realized, and the dissociation degree and grindability of mineral monomers are enhanced, and the device and the method have important significance for solving the problem of treatment of the existing complex refractory iron ores.
Disclosure of Invention
The invention aims to provide a microwave continuous suspension magnetization roasting system for treating iron ore, which adopts a mode of combining a pretreatment fluidizer with a reduction fluidizer provided with a microwave generating device and adopts a method of combining microwave heat-storage pretreatment and suspension magnetization sustainable roasting to selectively and rapidly heat iron ore materials, increase mineral separation indexes and realize high-efficiency comprehensive development and utilization of complex refractory iron ore.
The microwave continuous suspension magnetization roasting system for treating the iron ore comprises a feeding bin, a pretreatment fluidizer, a microwave cavity, a microwave generating device, a reduction fluidizer, a cooler and a collecting tank; a discharge hole at the bottom of the feeding bin is communicated with a feed inlet of a pretreatment fluidizer, a microwave cavity is sleeved outside the pretreatment fluidizer, a pretreatment baffle is arranged inside the pretreatment fluidizer to divide the interior of the pretreatment fluidizer into a pretreatment feed chamber and a pretreatment discharge chamber, the top edge of the pretreatment baffle is connected with the top plate of the pretreatment fluidizer, two side edges of the pretreatment baffle are connected with the side wall of the pretreatment fluidizer, and a gap between the bottom edge of the pretreatment baffle and the bottom plate of the pretreatment fluidizer is used as a pretreatment channel; the bottoms of the pretreatment feeding chamber and the pretreatment discharging chamber are respectively provided with a first air inlet and a second air inlet, and the top of the pretreatment feeding chamber is provided with an air outlet communicated with a feeding hole of the gas-solid separator; the feed inlet of the pretreatment fluidizer is arranged at the upper part of the pretreatment feed chamber; the discharge hole of the pretreatment fluidizer is arranged at the upper part of the pretreatment discharge chamber and is communicated with the feed hole of the reduction fluidizer; a reduction baffle is arranged in the reduction fluidizer to divide the interior of the reduction fluidizer into a reduction feeding chamber and a reduction discharging chamber, the top edge of the reduction baffle is connected with the top plate of the reduction fluidizer, two side edges of the reduction baffle are connected with the side wall of the reduction fluidizer, and the control between the bottom edge of the reduction baffle and the bottom plate of the reduction fluidizer is used as a reduction channel; the bottoms of the reduction feeding chamber and the reduction discharging chamber are respectively provided with a third air inlet and a fourth air inlet; the feed inlet of the reduction fluidizer is arranged at the upper part of the reduction feed chamber, and the discharge outlet of the reduction fluidizer is arranged at the upper part of the reduction discharge chamber and is communicated with the feed inlet of the cooler; the discharge hole of the cooler is opposite to the collecting tank; the microwave cavity is assembled with the microwave generating device.
In the system, the first air inlet is communicated with the first air storage tank through a pipeline with a first valve, and the second air inlet is communicated with the first air storage tank through a pipeline with a second valve.
In the system, the third air inlet is communicated with the second air storage tank through a pipeline with a third valve and a fourth valve, the fourth air inlet is communicated with the second air storage tank through a pipeline with a fifth valve and a fourth valve, and the fourth air inlet is also communicated with the third air storage tank through a pipeline with a sixth valve.
In the system, the discharge port of the gas-solid separator is opposite to the feeding bin.
In the system, the microwave generating device consists of a waveguide, a magnetron and an antenna cap, the waveguide is connected with a power supply through a lead, the waveguide is positioned below the magnetron, a microwave power regulator is assembled on the magnetron, and the antenna cap below the magnetron is inserted into the waveguide.
In the system, the tops of the pretreatment fluidizer, the reduction vulcanizer and the cooler are respectively provided with a first thermocouple, a second thermocouple and a third thermocouple, and the first thermocouple, the second thermocouple and the third thermocouple are respectively connected with a temperature measuring instrument through data lines; wherein the first thermocouple is positioned in the pretreatment discharging chamber, and the second thermocouple is positioned in the reduction discharging chamber.
The cooler is a tubular heat exchanger, and the cooling medium is water.
The volume ratio of the pretreatment feeding chamber to the pretreatment discharging chamber is 1 (4-8), and the height ratio of the pretreatment baffle to the pretreatment fluidizer is 1 (1-1.5); the volume ratio of the reduction feeding chamber to the reduction discharging chamber is 1 (4-8), and the height ratio of the reduction baffle to the reduction fluidizer is 1 (1-1.5).
The volume ratio of the pretreatment fluidizer to the reduction fluidizer is 1: 1.
The microwave continuous suspension magnetization roasting method for treating iron ore of the invention adopts the system and comprises the following steps:
1. crushing and grinding the iron ore into iron ore powder, then pouring the iron ore powder into a feeding bin, and continuously conveying the iron ore powder into a pretreatment fluidizer through the feeding bin;
2. protective gas is respectively introduced into the pretreatment feeding chamber and the pretreatment discharging chamber through the first gas inlet and the second gas inlet, so that iron ore powder in the pretreatment fluidizer is in a fluidized state, the protective gas is discharged from a gas outlet at the top of the pretreatment feeding chamber, and part of the iron ore powder is discharged with the protective gas and enters a gas-solid separator;
3. starting a microwave generating device, enabling generated microwaves to enter a microwave cavity, heating iron ore powder in the pretreatment fluidizer to 800-1100 ℃ through the microwave cavity, discharging the heated iron ore powder from a discharge hole of the pretreatment fluidizer, and enabling the heated iron ore powder to enter a reduction fluidizer;
4. Protective gas is respectively introduced into the reduction feeding chamber and the reduction discharging chamber through the third air inlet and the fourth air inlet, so that the heated iron ore powder in the reduction fluidizer is in a fluidized state; when the temperature of the heated iron ore powder is reduced to 450-600 ℃, introducing reducing gas into the reduction discharging chamber through the fourth gas inlet, carrying out reduction magnetizing roasting on the iron ore powder in the discharging chamber, and enabling the generated reduced material to enter a cooler along with the reducing gas;
5. and (3) after the temperature of the reduced material is reduced to be below 100 ℃ in a cooler, continuously feeding the reduced material into a collecting tank from a discharge hole of the cooler to obtain magnetized and roasted iron ore powder.
In the method, the solid material separated by the gas-solid separator enters the feeding bin.
The grade of the iron ore is 10-58%.
In the step 1, the iron ore is crushed and ground, namely, the iron ore is crushed to the particle size of less than or equal to 3mm, and then ground to the particle size of less than or equal to 0.074mm, wherein the part of the iron ore accounts for 50-70% of the total mass, so as to prepare the iron ore powder.
The protective gas is N2Or CO2Stored in the first and second gas tanks; the reducing gas is CO or H2、CH4Or water gas, stored in a third gas tank.
In the step 3, the retention time of the iron ore powder in the pretreatment fluidizer is 20-60 min.
In the step 4, the time for reducing, magnetizing and roasting the heated iron ore powder in the reducing fluidizer is 5-20 min.
In the step 4, when the reducing gas is introduced into the reduction discharging chamber, the introduction amount of the reducing gas and the introduction amount of the protective gas introduced into the reduction feeding chamber are 1: 9-4: 6 in a volume ratio.
In the method, after the reduction magnetization baking and sintering, the reducing gas is stopped from being introduced into the reduction discharge chamber, and the microwave generating device is closed; introducing protective gas into the reduction fluidizer and the pretreatment fluidizer to reduce the temperature; when the temperatures of the reduction fluidizer and the pretreatment fluidizer are below 300 ℃, the introduction of the protective gas is stopped.
In the method, the obtained magnetized and roasted iron ore powder is ground until the part with the particle size of less than or equal to 0.043mm accounts for 60-80% of the total mass, and then low-intensity magnetic separation is carried out under the condition of the magnetic field intensity of 70-90 kA/m to obtain magnetic separation iron ore concentrate, wherein the iron grade of the magnetic separation iron ore concentrate is more than or equal to 60%.
The iron recovery rate of the magnetic separation iron ore concentrate relative to the iron ore is more than or equal to 85 percent.
In the step 2, the ratio of the total volume of the protective gas introduced into the pretreatment feeding chamber and the pretreatment discharging chamber in unit time to the mass of the iron ore powder introduced into the pretreatment feeding chamber is 1-10 m 3And/kg, wherein the volume ratio of the protective gas introduced into the pretreatment feeding chamber to the protective gas introduced into the pretreatment discharging chamber is 1 (2-4).
In the step 3, when the protective gas is respectively introduced into the reduction feeding chamber and the reduction discharging chamber through the third gas inlet and the fourth gas inlet, the volume flow ratio of the protective gas introduced into the reduction feeding chamber to the protective gas introduced into the reduction discharging chamber is 1 (1.5-2); the ratio of the volume of the protective gas introduced into the reduction feeding chamber in unit time to the mass of the iron ore powder entering the pretreatment feeding chamber is 1-10 m3/kg。
Compared with the prior art, the invention has the outstanding advantages that:
1. compared with the traditional fluidized roasting device heated by resistance heat conduction or heat convection, the heating efficiency is improved by more than 6 times, and the sorting index is improved by more than 2%;
2. the microwave continuous suspension magnetizing roasting system not only concentrates the advantages of fluidized roasting and microwave heating, but also can realize the continuous operation of microwave fluidized magnetizing roasting compared with the applied microwave-fluidized intermittent roasting device;
3. the microwave continuous suspension magnetization roasting system not only concentrates the advantages of fluidization roasting and microwave heating, but also is provided with a pretreatment fluidizer and a reduction fluidizer respectively compared with the applied microwave-fluidization intermittent roasting device, so that the material heating and temperature rising stage and the reduction stage are separated, and the continuous and safe operation of the system is facilitated;
4. The microwave continuous suspension magnetizing roasting system not only concentrates the advantages of fluidized roasting and microwave heating, but also is provided with a pretreatment fluidizer compared with the applied microwave-fluidized intermittent roasting device, so that the system can effectively heat and preoxidize materials, and is beneficial to efficient subsequent magnetizing roasting.
Drawings
FIG. 1 is a schematic structural diagram of a microwave continuous suspension magnetizing roasting system for treating iron ore according to an embodiment of the present invention;
in the figure, 1, a feeding bin, 2, a pretreatment fluidizer, 3, a microwave power regulator, 4, a magnetron, 5, a microwave generating device, 6, an antenna cap, 7, a waveguide, 8, a microwave cavity, 9, a power supply, 10, a first valve, 11, a second valve, 12, a first gas storage tank, 13, a gas exhaust pipe, 14, a gas-solid separator, 15, a gas outlet, 16, a temperature measuring instrument, 17, a reduction fluidizer, 18, a cooler, 19, a collecting tank, 20, a fifth valve, 21 and a third valve. 22. A sixth valve, 23, a fourth valve, 24, a first thermocouple, 25, a second thermocouple, 26, a third thermocouple, 27, a second air storage tank, 28 and a third air storage tank.
Detailed Description
The present invention is further illustrated by the following examples.
The pretreatment fluidizer and the pretreatment baffle in the embodiment of the invention are made of quartz.
The reduction fluidizer and the reduction baffle in the embodiment of the invention are made of stainless steel, and the outside of the reduction fluidizer and the reduction baffle is wrapped by heat insulation cotton.
The power regulation and control range of the microwave power meter adopted in the embodiment of the invention is 50-2400W.
The feeding bin, the gas-solid separator, the microwave cavity, the reduction fluidizer, the cooler and the collecting tank in the embodiment of the invention are made of stainless steel.
The temperature measuring range of the thermocouple in the embodiment of the invention is 0-1100 ℃.
The temperature measuring instrument adopted in the embodiment of the invention is a digital display temperature measuring instrument.
The waveguide model employed in the embodiments of the present invention is BJ 26.
The magnetron used in the embodiment of the invention is 2M 343K.
The antenna cap adopted in the embodiment of the invention is made of stainless steel.
The microwave frequency in the embodiment of the invention is 2450 +/-25 MHz.
In the embodiment of the invention, the flow speed of the protective gas is 0.1-20 m3H; the flow rate of the reducing gas is 0.1 to 20m3/h。
In the embodiment of the invention, the iron grade of the magnetic separation iron concentrate is 60-70%.
Example 1
The structure of the microwave continuous suspension magnetization roasting system for treating iron ore is shown in figure 1, and comprises a feeding bin 1, a pretreatment fluidizer 2, a microwave cavity 8, a microwave generating device 5, a reduction fluidizer 17, a cooler 18 and a collecting tank 19;
A discharge hole at the bottom of the feeding bin 1 is communicated with a feed inlet of the pretreatment fluidizer 2, a microwave cavity 8 is sleeved outside the pretreatment fluidizer 2, a pretreatment baffle is arranged inside the pretreatment fluidizer 2 to divide the interior of the pretreatment fluidizer 2 into a pretreatment feeding chamber and a pretreatment discharging chamber, the top edge of the pretreatment baffle is connected with the top plate of the pretreatment fluidizer 2, two side edges of the pretreatment baffle are connected with the side wall of the pretreatment fluidizer 2, and a gap between the bottom edge of the pretreatment baffle and the bottom plate of the pretreatment fluidizer 2 is used as a pretreatment channel;
the bottoms of the pretreatment feeding chamber and the pretreatment discharging chamber are respectively provided with a first air inlet and a second air inlet, and the top of the pretreatment feeding chamber is provided with an air outlet 15 communicated with a feeding hole of a gas-solid separator 14; the gas outlet of the gas-solid separator 14 is connected with a gas exhaust pipe 13;
the feed inlet of the pretreatment fluidizer 2 is arranged at the upper part of the pretreatment feed chamber; the discharge hole of the pretreatment fluidizer 2 is arranged at the upper part of the pretreatment discharge chamber and is communicated with the feed hole of the reduction fluidizer 17;
a reduction baffle is arranged in the reduction fluidizer 17 to divide the interior of the reduction fluidizer 17 into a reduction feeding chamber and a reduction discharging chamber, the top edge of the reduction baffle is connected with the top plate of the reduction fluidizer 17, two side edges of the reduction baffle are connected with the side wall of the reduction fluidizer 17, and the control between the bottom edge of the reduction baffle and the bottom plate of the reduction fluidizer 17 is used as a reduction channel;
The bottoms of the reduction feeding chamber and the reduction discharging chamber are respectively provided with a third air inlet and a fourth air inlet;
the feed inlet of the reduction fluidizer 17 is arranged at the upper part of the reduction feed chamber, and the discharge outlet of the reduction fluidizer 17 is arranged at the upper part of the reduction discharge chamber and is communicated with the feed inlet of the cooler 18;
the discharge port of the cooler 18 is opposite to the collection tank 19;
the microwave cavity 8 is assembled with the microwave generating device 5;
the first air inlet is communicated with a first air storage tank 12 through a pipeline with a first valve 10, and the second air inlet is communicated with the first air storage tank 12 through a pipeline with a second valve 11; the gas in the first gas storage tank 12 is N2；
The third inlet communicates with the second reservoir 27 via a conduit with a third valve 21 and a fourth valve 23 in series, the fourth inlet communicates with the second reservoir 27 via a conduit with a fifth valve 20 and a fourth valve 23 in series, and the fourth inlet also communicates with the third reservoir 28 via a conduit with a sixth valve 22;
the gas in the second gas tank 27 is N2The gas in the third gas tank 28 is CO;
the discharge port of the gas-solid separator 14 is opposite to the feeding bin 1;
the microwave generating device 5 consists of a waveguide 7, a magnetron 4 and an antenna cap 6, the waveguide 7 is connected with a power supply 9 through a lead, the waveguide 7 is positioned below the magnetron 4, the magnetron 4 is provided with a microwave power regulator 3, and the antenna cap 6 below the magnetron 4 is inserted into the waveguide 7;
The tops of the pretreatment fluidizer 2, the reduction vulcanizer 17 and the cooler 18 are respectively provided with a first thermocouple 24, a second thermocouple 25 and a third thermocouple 26, and the first thermocouple 24, the second thermocouple 25 and the third thermocouple 26 are respectively connected with the temperature measuring instrument 16 through data lines; wherein the first thermocouple 24 is positioned in the pretreatment discharging chamber, and the second thermocouple 25 is positioned in the reduction discharging chamber;
the cooler 18 is a tubular heat exchanger, and the cooling medium is water;
the volume ratio of the pretreatment feeding chamber to the pretreatment discharging chamber is 1:6, and the height ratio of the pretreatment baffle to the pretreatment fluidizer 2 is 1: 1.1; the volume ratio of the reduction feeding chamber to the reduction discharging chamber is 1:6, and the height ratio of the reduction baffle to the reduction fluidizer 17 is 1: 1.1;
the volume ratio of the pretreatment fluidizer 2 to the reduction fluidizer 17 is 1: 1;
the method comprises the following steps:
crushing and grinding the iron ore, namely crushing the iron ore until the particle size is less than or equal to 3mm, grinding the iron ore until the part with the particle size of less than or equal to 0.074mm accounts for 60 percent of the total mass to prepare iron ore powder, pouring the iron ore powder into a feeding bin, and continuously conveying the iron ore powder into a pretreatment fluidizer through the feeding bin; the adopted iron ore is hematite, and the iron grade is 34.6 percent;
protective gas is respectively introduced into the pretreatment feeding chamber and the pretreatment discharging chamber through the first gas inlet and the second gas inlet, so that iron ore powder in the pretreatment fluidizer is in a fluidized state, the protective gas is discharged from a gas outlet at the top of the pretreatment feeding chamber, and part of the iron ore powder is discharged with the protective gas and enters a gas-solid separator; solid materials separated by the gas-solid separator enter a feeding bin; gas materials separated by the gas-solid separator are discharged through an exhaust pipe; the ratio of the total volume of the protective gas introduced into the pretreatment feeding chamber and the pretreatment discharging chamber in unit time to the mass of the iron ore powder introduced into the pretreatment feeding chamber is 4m 3Kg, wherein the volume ratio of the protective gas introduced into the pretreatment feeding chamber to the pretreatment discharging chamber is 1: 3;
starting a microwave generating device, enabling generated microwaves to enter a microwave cavity, heating iron ore powder in the pretreatment fluidizer to 900 ℃ through the microwave cavity, discharging the heated iron ore powder from a discharge hole of the pretreatment fluidizer, and enabling the heated iron ore powder to enter a reduction fluidizer; the retention time of the iron ore powder in the pretreatment fluidizer is 40 min; when the third air inlet and the fourth air inlet respectively introduce protective gas into the reduction feeding chamber and the reduction discharging chamber, the volume flow ratio of the protective gas introduced into the reduction feeding chamber to the protective gas introduced into the reduction discharging chamber is 1: 1.8; the ratio of the volume of protective gas introduced into the reduction feed chamber per unit time to the mass of iron ore powder introduced into the pretreatment feed chamber was 6m3/kg；
Protective gas is respectively introduced into the reduction feeding chamber and the reduction discharging chamber through the third air inlet and the fourth air inlet, so that the heated iron ore powder in the reduction fluidizer is in a fluidized state; when the temperature of the heated iron ore powder is reduced to 550 ℃, introducing reducing gas into the reduction discharging chamber through the fourth gas inlet, carrying out reduction magnetizing roasting on the iron ore powder in the discharging chamber, and enabling the generated reduced material to enter a cooler along with the reducing gas; reducing and magnetizing roasting the heated iron ore powder in a reducing fluidizer for 15 min; when reducing gas is introduced into the reduction discharging chamber, the volume ratio of the introduction amount of the reducing gas to the introduction amount of the protective gas introduced into the reduction feeding chamber is 2: 8;
After the temperature of the reduced material is reduced to be below 100 ℃ in a cooler, the reduced material continuously enters a collecting tank from a discharge hole of the cooler to obtain magnetized and roasted iron ore powder;
after the reduction magnetization baking and sintering, stopping introducing the reducing gas into the reduction discharge chamber, and closing the microwave generating device; introducing protective gas into the reduction fluidizer and the pretreatment fluidizer to reduce the temperature; stopping introducing the protective gas when the temperatures of the reduction fluidizer and the pretreatment fluidizer are lower than 300 ℃;
grinding the obtained magnetized and roasted iron ore powder until the part with the particle size of less than or equal to 0.043mm accounts for 70% of the total mass, and then carrying out low-intensity magnetic separation under the condition of the magnetic field intensity of 80kA/m to obtain magnetic separation iron ore concentrate with the iron grade of 64.7%;
the iron recovery rate of the magnetic separation iron ore concentrate relative to the iron ore is 89.4 percent.
Example 2
The system configuration is different from embodiment 1 in that:
(1) the gas in the first gas storage tank is CO2(ii) a The gas in the second gas storage tank is CO2The gas in the third gas storage tank is H2；
(2) The volume ratio of the pretreatment feeding chamber to the pretreatment discharging chamber is 1:5, and the height ratio of the pretreatment baffle to the pretreatment fluidizer is 1: 1; the volume ratio of the reduction feeding chamber to the reduction discharging chamber is 1:5, and the height ratio of the reduction baffle to the reduction fluidizer is 1: 1;
The method is the same as example 1, except that:
(1) the part with the grain diameter less than or equal to 0.074mm in the iron ore powder accounts for 70 percent of the total mass, and the iron grade of the iron ore is 12.3 percent;
(2) the ratio of the total volume of the protective gas introduced into the pretreatment feeding chamber and the pretreatment discharging chamber in unit time to the mass of the iron ore powder introduced into the pretreatment feeding chamber is 6m3Kg, wherein the volume ratio of the protective gas introduced into the pretreatment feeding chamber to the protective gas introduced into the pretreatment discharging chamber is 1: 2;
(3) heating the iron ore powder in the pretreatment fluidizer to 1100 ℃ through a microwave cavity; the retention time of the iron ore powder in the pretreatment fluidizer is 20 min; when the third air inlet and the fourth air inlet respectively introduce protective gas into the reduction feeding chamber and the reduction discharging chamber, the volume flow ratio of the protective gas introduced into the reduction feeding chamber to the protective gas introduced into the reduction discharging chamber is 1: 2; the ratio of the volume of protective gas introduced into the reduction feed chamber per unit time to the mass of iron ore fines introduced into the pretreatment feed chamber was 9m3/kg；
(4) When the temperature of the heated iron ore powder is reduced to 600 ℃, introducing reducing gas into the reduction discharging chamber through the fourth gas inlet, and carrying out reduction magnetizing roasting on the iron ore powder in the discharging chamber; reducing and magnetizing roasting the heated iron ore powder in a reducing fluidizer for 5 min; when reducing gas is introduced into the reduction discharging chamber, the introduction amount of the reducing gas and the introduction amount of the protective gas introduced into the reduction feeding chamber are 3:7 in volume ratio;
(5) Grinding the obtained magnetized and roasted iron ore powder until the part with the particle size of less than or equal to 0.043mm accounts for 80% of the total mass, and then carrying out low intensity magnetic separation under the condition of the magnetic field intensity of 70kA/m to obtain magnetic separation iron ore concentrate with the iron grade of 65.3%; the iron recovery rate of the magnetic iron concentrate relative to the iron ore was 86.6%.
Example 3
The system configuration is different from embodiment 1 in that:
(1) the gas in the third gas storage tank is CH4；
(2) The volume ratio of the pretreatment feeding chamber to the pretreatment discharging chamber is 1:8, and the height ratio of the pretreatment baffle to the pretreatment fluidizer is 1: 1.5; the volume ratio of the reduction feeding chamber to the reduction discharging chamber is 1:8, and the height ratio of the reduction baffle to the reduction fluidizer is 1: 1.5;
the method is the same as example 1, except that:
(1) the part with the grain diameter less than or equal to 0.074mm in the iron ore powder accounts for 50 percent of the total mass, and the iron grade of the iron ore is 35.1 percent;
(2) the ratio of the total volume of the protective gas introduced into the pretreatment feeding chamber and the pretreatment discharging chamber in unit time to the mass of the iron ore powder introduced into the pretreatment feeding chamber is 8m3The volume ratio of protective gas introduced into the pretreatment feeding chamber to protective gas introduced into the pretreatment discharging chamber is 1: 4;
(3) heating the iron ore powder in the pretreatment fluidizer to 1000 ℃ through a microwave cavity; the retention time of the iron ore powder in the pretreatment fluidizer is 30 min; when the third air inlet and the fourth air inlet respectively introduce protective gas into the reduction feeding chamber and the reduction discharging chamber, the volume flow ratio of the protective gas introduced into the reduction feeding chamber to the protective gas introduced into the reduction discharging chamber is 1: 1.5; the ratio of the volume of protective gas introduced into the reduction feed chamber per unit time to the mass of iron ore powder introduced into the pretreatment feed chamber was 3m 3/kg；
(4) When the temperature of the heated iron ore powder is reduced to 450 ℃, introducing reducing gas into the reduction discharging chamber through the fourth gas inlet, and carrying out reduction magnetizing roasting on the iron ore powder in the discharging chamber; reducing and magnetizing roasting the heated iron ore powder in a reducing fluidizer for 20 min; when reducing gas is introduced into the reduction discharging chamber, the introduction amount of the reducing gas and the introduction amount of the protective gas introduced into the reduction feeding chamber are 4:6 in volume ratio;
(5) grinding the obtained magnetized and roasted iron ore powder until the part with the particle size of less than or equal to 0.043mm accounts for 65% of the total mass, and then carrying out low intensity magnetic separation under the condition of the magnetic field intensity of 75kA/m to obtain magnetic separation iron ore concentrate with the iron grade of 61.2%; the iron recovery rate of the magnetic separation iron concentrate relative to the iron ore is 87.2 percent.
Example 4
The system configuration is different from embodiment 1 in that:
(1) The gas in the first gas storage tank is CO2(ii) a The gas in the second gas storage tank is CO2The gas in the third gas storage tank is water gas;
(2) the volume ratio of the pretreatment feeding chamber to the pretreatment discharging chamber is 1:4, and the height ratio of the pretreatment baffle to the pretreatment fluidizer is 1: 1.3; the volume ratio of the reduction feeding chamber to the reduction discharging chamber is 1:4, and the height ratio of the reduction baffle to the reduction fluidizer is 1: 1.3;
The method is the same as example 1, except that:
(1) the part with the grain diameter less than or equal to 0.074mm in the iron ore powder accounts for 55 percent of the total mass, and the iron grade of the iron ore is 52.4 percent;
(2) the ratio of the total volume of the protective gas introduced into the pretreatment feeding chamber and the pretreatment discharging chamber in unit time to the mass of the iron ore powder introduced into the pretreatment feeding chamber is 2m3The volume ratio of protective gas introduced into the pretreatment feeding chamber to protective gas introduced into the pretreatment discharging chamber is 1: 4;
(3) heating the iron ore powder in the pretreatment fluidizer to 800 ℃ through a microwave cavity; the retention time of the iron ore powder in the pretreatment fluidizer is 60 min; when the third air inlet and the fourth air inlet respectively introduce protective gas into the reduction feeding chamber and the reduction discharging chamber, the volume flow ratio of the protective gas introduced into the reduction feeding chamber to the protective gas introduced into the reduction discharging chamber is 1: 1.9; the ratio of the volume of protective gas introduced into the reduction feed chamber per unit time to the mass of iron ore powder introduced into the pretreatment feed chamber is 2m3/kg；
(4) When the temperature of the heated iron ore powder is reduced to 500 ℃, introducing reducing gas into the reduction discharging chamber through the fourth gas inlet, and carrying out reduction magnetizing roasting on the iron ore powder in the discharging chamber; reducing and magnetizing roasting the heated iron ore powder in a reduction fluidizer for 10 min; when reducing gas is introduced into the reduction discharging chamber, the introduction amount of the reducing gas and the introduction amount of the protective gas introduced into the reduction feeding chamber are 1:9 in volume ratio;
(5) Grinding the obtained magnetized and roasted iron ore powder until the part with the particle size of less than or equal to 0.043mm accounts for 60 percent of the total mass, and then carrying out low-intensity magnetic separation under the condition of the magnetic field intensity of 90kA/m to obtain magnetic separation iron ore concentrate with the iron grade of 68.9 percent; the iron recovery rate of the magnetic separation iron concentrate relative to the iron ore is 85 percent.
Claims (2)
1. A microwave continuous suspension magnetization roasting system for treating iron ore is characterized by comprising a feeding bin, a pretreatment fluidizer, a microwave cavity, a microwave generating device, a reduction fluidizer, a cooler and a collecting tank; a discharge hole at the bottom of the feeding bin is communicated with a feed inlet of a pretreatment fluidizer, a microwave cavity is sleeved outside the pretreatment fluidizer, a pretreatment baffle is arranged inside the pretreatment fluidizer to divide the interior of the pretreatment fluidizer into a pretreatment feed chamber and a pretreatment discharge chamber, the top edge of the pretreatment baffle is connected with the top plate of the pretreatment fluidizer, two side edges of the pretreatment baffle are connected with the side wall of the pretreatment fluidizer, and a gap between the bottom edge of the pretreatment baffle and the bottom plate of the pretreatment fluidizer is used as a pretreatment channel; the bottoms of the pretreatment feeding chamber and the pretreatment discharging chamber are respectively provided with a first air inlet and a second air inlet, and the top of the pretreatment feeding chamber is provided with an air outlet communicated with a feeding hole of the gas-solid separator; the feed inlet of the pretreatment fluidizer is arranged at the upper part of the pretreatment feed chamber; the discharge hole of the pretreatment fluidizer is arranged at the upper part of the pretreatment discharge chamber and is communicated with the feed hole of the reduction fluidizer; a reduction baffle is arranged in the reduction fluidizer to divide the interior of the reduction fluidizer into a reduction feeding chamber and a reduction discharging chamber, the top edge of the reduction baffle is connected with the top plate of the reduction fluidizer, two side edges of the reduction baffle are connected with the side wall of the reduction fluidizer, and the control between the bottom edge of the reduction baffle and the bottom plate of the reduction fluidizer is used as a reduction channel; the bottoms of the reduction feeding chamber and the reduction discharging chamber are respectively provided with a third air inlet and a fourth air inlet; the feed inlet of the reduction fluidizer is arranged at the upper part of the reduction feed chamber, and the discharge outlet of the reduction fluidizer is arranged at the upper part of the reduction discharge chamber and is communicated with the feed inlet of the cooler; the discharge hole of the cooler is opposite to the collecting tank; the microwave cavity is assembled with the microwave generating device; the first air inlet is communicated with a first air storage tank through a pipeline with a first valve, and the second air inlet is communicated with the first air storage tank through a pipeline with a second valve; the third air inlet is communicated with a second air storage tank through a pipeline with a third valve and a fourth valve, the fourth air inlet is communicated with the second air storage tank through a pipeline with a fifth valve and a fourth valve, and the fourth air inlet is also communicated with the third air storage tank through a pipeline with a sixth valve; the microwave generating device consists of a waveguide, a magnetron and an antenna cap, wherein the waveguide is connected with a power supply through a lead, the waveguide is positioned below the magnetron, a microwave power regulator is assembled on the magnetron, and the antenna cap below the magnetron is inserted into the waveguide; the top parts of the pretreatment fluidizer, the reduction fluidizer and the cooler are respectively provided with a first thermocouple, a second thermocouple and a third thermocouple, and the first thermocouple, the second thermocouple and the third thermocouple are respectively connected with a temperature measuring instrument through data lines; wherein the first thermocouple is positioned in the pretreatment discharging chamber, and the second thermocouple is positioned in the reduction discharging chamber; the volume ratio of the pretreatment feeding chamber to the pretreatment discharging chamber is 1 (4-8), and the height ratio of the pretreatment baffle to the pretreatment fluidizer is 1 (1-1.5); the volume ratio of the reduction feeding chamber to the reduction discharging chamber is 1 (4-8), and the height ratio of the reduction baffle to the reduction fluidizer is 1 (1-1.5); the volume ratio of the treatment fluidizer to the reduction fluidizer is 1: 1.
2. A microwave continuous suspension magnetizing roasting method for processing iron ore, which is characterized by adopting the system of claim 1 and comprising the following steps:
(1) crushing and grinding the iron ore into iron ore powder, then pouring the iron ore powder into a feeding bin, and continuously conveying the iron ore powder into a pretreatment fluidizer through the feeding bin; the iron grade of the iron ore is 10-58%;
(2) protective gas is respectively introduced into the pretreatment feeding chamber and the pretreatment discharging chamber through the first gas inlet and the second gas inlet, so that iron ore powder in the pretreatment fluidizer is in a fluidized state, the protective gas is discharged from a gas outlet at the top of the pretreatment feeding chamber, and part of the iron ore powder is discharged with the protective gas and enters a gas-solid separator;
(3) starting a microwave generating device, enabling generated microwaves to enter a microwave cavity, heating iron ore powder in the pretreatment fluidizer to 800-1100 ℃ through the microwave cavity, discharging the heated iron ore powder from a discharge hole of the pretreatment fluidizer, and enabling the heated iron ore powder to enter a reduction fluidization chamber;
(4) protective gas is respectively introduced into the reduction feeding chamber and the reduction discharging chamber through the third air inlet and the fourth air inlet, so that the heated iron ore powder in the reduction fluidizer is in a fluidized state; when the temperature of the heated iron ore powder is reduced to 450-600 ℃, introducing reducing gas into the reduction discharging chamber through the fourth gas inlet, carrying out reduction magnetizing roasting on the iron ore powder in the discharging chamber, and enabling the generated reduced material to enter a cooler along with the reducing gas;
(5) After the temperature of the reduced material is reduced to be below 100 ℃ in a cooler, the reduced material continuously enters a collecting tank from a discharge hole of the cooler to obtain magnetized and roasted iron ore powder; the protective gas is N2Or CO2The reducing gas is CO or H2、CH4Or water gas; grinding the obtained magnetized and roasted iron ore powder until the part with the particle size of less than or equal to 0.043mm accounts for 60-80% of the total mass, and then carrying out low-intensity magnetic separation under the condition of 70-90 kA/m of magnetic field intensity to obtain magnetic separation iron ore concentrate, wherein the iron grade of the magnetic separation iron ore concentrate is more than or equal to 60%; the iron recovery rate of the magnetic separation iron ore concentrate relative to the iron ore is more than or equal to 85 percent.
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