Immersion type suspension magnetizing roasting system and process for low-grade refractory iron ore

Abstract

The invention discloses an immersion type suspension magnetization roasting system for low-grade refractory iron ore, which comprises a crushing and pulverizing device, a suspension magnetization roasting furnace, a magnetic separation device, a flue gas circulation assembly and a reducing gas circulation assembly which are connected in sequence, and a feed port of the suspension magnetization roasting furnace is formed in the top of the suspension magnetization roasting furnace; the discharge hole is formed in the bottom of the suspension magnetization roasting furnace, the upper part of a furnace chamber of the suspension magnetization roasting furnace adopts a gas radiant tube to supply heat so as to form a heating interval, and the lower part of the furnace chamber of the suspension magnetization roasting furnace is a cooling interval. According to the invention, the powder is fed into the furnace, is suspended under the action of airflow and is in full contact with the reducing gas for reduction, so that indirect heat supply of the roasting furnace can be realized, only the reducing gas and reduction products exist in the roasting furnace, and the damage of combustion waste gas to the atmosphere in the furnace does not exist. Materials are fed into the furnace from the top of the furnace, fluidization and boiling are not needed, and power consumption is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and more specifically, to an immersion suspension magnetization roasting system and process for low-grade refractory iron ore. Background Art

[0002] The field of mineral processing and metallurgy has done a lot of work on improving the grade of refractory hematite, siderite and limonite. In particular, the progress of magnetic separation technology and equipment has made magnetic roasting an effective means of processing refractory iron ore.

[0003] Magnetic roasting is to heat weakly magnetic iron ore under set atmosphere conditions to undergo physical and chemical reactions to transform it into strongly magnetic magnetite or hematite, which is beneficial to the subsequent magnetic separation of iron ore and improves the grade of iron ore. According to different iron ores, magnetic roasting is divided into reduction roasting, neutral roasting, oxidation roasting, oxidation-reduction roasting, and reduction-oxidation roasting. At present, the roasting process is mainly achieved through vertical furnaces, rotary kilns, and fluidized bed furnaces. The traditional roasting vertical furnace is filled with materials, which move downward under the action of the bottom discharge to undergo a reduction reaction. In order to ensure air permeability, the materials are required to be lump ore, which makes it impossible for the traditional vertical furnace to use radiant tubes for indirect heating. The heat required for roasting comes from the partial combustion of the reducing gas. The traditional fluidized bed furnace roasting uses partial combustion of gas as the heat source and reducing gas, and as a fluidizing gas to drive the material to suspend. There is a destruction of the reducing atmosphere in the furnace by the combustion exhaust gas. At the same time, the fluidized bed furnace has problems such as high energy consumption and unstable operation. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages according to the present invention, an immersed suspension magnetization roasting system for low-grade refractory iron ore is provided, comprising a crushing and powder making device, a suspension magnetization roasting furnace and a magnetic separation device connected in sequence, wherein the feed inlet of the suspension magnetization roasting furnace is arranged at the top of the suspension magnetization roasting furnace, and the discharge port is arranged at the bottom of the suspension magnetization roasting furnace, the suspension magnetization roasting furnace is a low-pressure airtight device, the upper part of the furnace cavity of the suspension magnetization roasting furnace adopts gas radiation tubes for heating to form a heating zone, and the lower part of the furnace cavity of the suspension magnetization roasting furnace is a cooling zone;

[0006] The system further comprises: a flue gas circulation component and a reducing gas circulation component;

[0007] The flue gas circulation assembly comprises: a first circulation fan, a heat exchanger and a smoke exhaust fan, the air inlet of the first circulation fan is connected to the air outlet of the gas radiation tube, the air outlet of the first circulation fan is connected to the air inlet of the crushing and pulverizing device, the air outlet of the crushing and pulverizing device is connected to the heating medium inlet of the heat exchanger, the heating medium outlet of the heat exchanger is connected to the air inlet of the first circulation fan, and the air outlet of the crushing and pulverizing device is also connected to the air inlet of the smoke exhaust fan;

[0008] The reducing gas circulation component includes: a second circulating fan, a cyclone collector, the heat exchanger, and a venturi washing tower. An air inlet of the second circulating fan is connected to the reducing gas delivery pipeline, and an air outlet of the second circulating fan is connected to the air inlet of the suspended magnetization roasting furnace. The air inlet of the suspended magnetization roasting furnace is arranged at the lower part of the furnace chamber of the suspended magnetization roasting furnace, the air outlet of the suspended magnetization roasting furnace is connected to the air inlet of the cyclone collector, and the air outlet of the suspended magnetization roasting furnace is arranged at the top of the suspended magnetization roasting furnace. The air outlet of the cyclone collector is connected to the heated medium inlet of the heat exchanger, the heated medium outlet of the heat exchanger is connected to the air inlet of the venturi washing tower, the air outlet of the venturi washing tower is connected to another air inlet of the second circulating fan, and the discharge port of the cyclone collector is connected to the feed port of the magnetic separation device.

[0009] The present invention also provides a low-grade refractory iron ore immersion suspension magnetic roasting process applied to the above-mentioned low-grade refractory iron ore immersion suspension magnetic roasting system, comprising:

[0010] The iron ore is fed into the crushing and pulverizing device for crushing and pulverizing;

[0011] Passing gas into the gas radiation tube to radiate heat to the upper part of the furnace chamber of the suspension magnetization roasting furnace through gas combustion;

[0012] The high-temperature flue gas discharged from the gas-fired radiation tube is sucked by the first circulating fan and passed into the crushing and powder-making device to dry and air-select the mineral powder;

[0013] The ore powder processed by the crushing and powder making device enters the suspension magnetization roasting furnace from the feed port of the suspension magnetization roasting furnace and falls under the action of gravity, and the reducing gas introduced into the suspension magnetization roasting furnace by the second circulation fan flows from the lower part of the furnace chamber of the suspension magnetization roasting furnace into the upper part of the furnace chamber and suspends the ore powder, so that the ore powder is suspended and magnetized roasted in the upper part of the furnace chamber of the suspension magnetization roasting furnace, and the ore powder is reduced by the reducing gas;

[0014] The reduced ore powder continues to fall under the action of gravity, enters the lower part of the furnace chamber of the suspension magnetic roasting furnace, and contacts with the reducing gas that has just entered the suspension magnetic roasting furnace. The two perform heat exchange, so that the reduced ore powder is cooled, and the reducing gas that has just entered the suspension magnetic roasting furnace is preheated. The cooled ore powder then enters the magnetic separation device for magnetic separation to obtain high-grade concentrated ore powder.

[0015] Among them, the high-temperature exhaust gas discharged from the crushing and pulverizing device enters the heating medium airway of the heat exchanger, the reducing gas from the upper part of the furnace chamber of the suspended magnetized roasting furnace enters the cyclone collector from the outlet of the suspended magnetized roasting furnace, the mineral powder separated by the cyclone collector enters the magnetic separation device, the reducing gas separated by the cyclone collector enters the heated medium airway of the heat exchanger, the high-temperature exhaust gas and the reducing gas exchange heat in the heat exchanger, and then the high-temperature exhaust gas enters the first circulation fan for recycling, the reducing gas enters the Venturi washing tower for washing, and then enters the second circulation fan for recycling.

[0016] Preferably, the iron ore is processed to a particle size of 1 mm or less in a crushing and pulverizing device.

[0017] Preferably, the working gas pressure in the suspension magnetization roasting furnace is normal pressure to 0.8 MPa, the maximum reduction temperature is 800° C., and the reduction time of the mineral powder in the magnetization roasting furnace is 8 to 60 seconds.

[0018] Preferably, the optimal reduction temperature in the suspended magnetization roasting furnace is 570°C.

[0019] Preferably, the fuel gas is one of natural gas, converter gas, blast furnace gas, coal gas and hydrogen.

[0020] Preferably, the fuel gas is hydrogen.

[0021] The present invention has at least the following beneficial effects:

[0022] 1. The roasting furnace of the present invention adopts powder material to enter the furnace. The powder material is suspended under the action of the airflow and fully contacted with the reducing gas for reduction, which can realize indirect heating of the roasting furnace. This can ensure that there are only reducing gas and reduction products in the roasting furnace, and there is no destruction of the atmosphere in the furnace by combustion exhaust gas. The material enters the furnace from the top of the furnace, and fluidization boiling is not required, which greatly reduces power consumption;

[0023] 2. The magnetization roasting process of the present invention adopts indirect heating by radiant tubes, and the fuel types are wide. The temperature requirements in the furnace can be guaranteed by external heating, and the degree of magnetization can be controlled more accurately; indirect heating does not require heat storage for the iron ore entering the furnace, and the temperature stability and consistent reduction depth can be guaranteed throughout the reduction process;

[0024] 3. The present invention adopts a process of separating fuel and reducing gas, which can reduce the non-process consumption of reducing gas. And through the design of the circulation system, the reducing gas can be fully utilized;

[0025] 4. The working pressure of the magnetized roasting furnace of the present invention is normal pressure to 0.8Mpa. Compared with the traditional roasting shaft furnace, the working pressure can be increased to increase the concentration of reducing gas, increase the reduction speed, and improve the efficiency; by increasing the circulation rate of reducing gas, the concentration of reaction gas can be stabilized in the whole reaction process to ensure the uniformity of reduction;

[0026] 5. The temperature and gas concentration in the roasting furnace of the present invention are stable, the mineral powder and the reducing gas move in opposite directions, and the optimal process conditions are achieved in the heating zone of the roasting furnace, ensuring the reduction depth. In the traditional boiling furnace, the fuel gas drives the raw materials to suspend and move in the same direction. When the material temperature is low, the reducing gas concentration is high, and when the material temperature is high, the reducing gas concentration is low and the exhaust gas concentration is high, which seriously restricts the reduction reaction.

[0027] 6. The present invention is a fine-grained iron ore roasting process, which has a wide range of raw material adaptability, does not require processes such as lump ore and pelletizing, uses hydrogen as a reducing gas, and does not produce greenhouse gas pollution.

[0028] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of the immersed suspended magnetic roasting system for low-grade refractory iron ore according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0031] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0032] <Example 1>

[0033] like Figure 1 As shown, an immersed suspension magnetization roasting system for low-grade refractory iron ore comprises a crushing and pulverizing device, a suspension magnetization roasting furnace and a magnetic separation device connected in sequence, wherein the feed inlet of the suspension magnetization roasting furnace is arranged at the top of the suspension magnetization roasting furnace, and the discharge port is arranged at the bottom of the suspension magnetization roasting furnace, the suspension magnetization roasting furnace is a low-pressure airtight device, the upper part of the furnace cavity of the suspension magnetization roasting furnace adopts gas radiation tubes for heating to form a heating zone, and the lower part of the furnace cavity of the suspension magnetization roasting furnace is a cooling zone;

[0034] The system further comprises: a flue gas circulation component and a reducing gas circulation component;

[0035] The flue gas circulation assembly comprises: a first circulation fan, a heat exchanger and a smoke exhaust fan, the air inlet of the first circulation fan is connected to the air outlet of the gas radiation tube, the air outlet of the first circulation fan is connected to the air inlet of the crushing and pulverizing device, the air outlet of the crushing and pulverizing device is connected to the heating medium inlet of the heat exchanger, the heating medium outlet of the heat exchanger is connected to the air inlet of the first circulation fan, and the air outlet of the crushing and pulverizing device is also connected to the air inlet of the smoke exhaust fan;

[0036] The reducing gas circulation component includes: a second circulating fan, a cyclone collector, the heat exchanger, and a venturi washing tower. An air inlet of the second circulating fan is connected to the reducing gas delivery pipeline, and an air outlet of the second circulating fan is connected to the air inlet of the suspended magnetization roasting furnace. The air inlet of the suspended magnetization roasting furnace is arranged at the lower part of the furnace chamber of the suspended magnetization roasting furnace, the air outlet of the suspended magnetization roasting furnace is connected to the air inlet of the cyclone collector, and the air outlet of the suspended magnetization roasting furnace is arranged at the top of the suspended magnetization roasting furnace. The air outlet of the cyclone collector is connected to the heated medium inlet of the heat exchanger, the heated medium outlet of the heat exchanger is connected to the air inlet of the venturi washing tower, the air outlet of the venturi washing tower is connected to another air inlet of the second circulating fan, and the discharge port of the cyclone collector is connected to the feed port of the magnetic separation device.

[0037] The working process of the above-mentioned suspension magnetization roasting system is as follows: the iron ore is sent to the above-mentioned crushing and pulverizing device for crushing and pulverizing;

[0038] Passing gas into the gas radiation tube to radiate heat to the upper part of the furnace chamber of the suspension magnetization roasting furnace through gas combustion;

[0039] The high-temperature flue gas discharged from the gas-fired radiation tube is sucked by the first circulating fan and passed into the crushing and powder-making device to dry and air-select the mineral powder;

[0040] The ore powder processed by the crushing and powder making device enters the suspension magnetization roasting furnace from the feed port of the suspension magnetization roasting furnace and falls under the action of gravity, and the reducing gas introduced into the suspension magnetization roasting furnace by the second circulation fan flows from the lower part of the furnace chamber of the suspension magnetization roasting furnace into the upper part of the furnace chamber and suspends the ore powder, so that the ore powder is suspended and magnetized roasted in the upper part of the furnace chamber of the suspension magnetization roasting furnace, and the ore powder is reduced by the reducing gas;

[0041] The reduced ore powder continues to fall under the action of gravity, enters the lower part of the furnace chamber of the suspension magnetic roasting furnace, and contacts with the reducing gas that has just entered the suspension magnetic roasting furnace. The two perform heat exchange, so that the reduced ore powder is cooled, and the reducing gas that has just entered the suspension magnetic roasting furnace is preheated. The cooled ore powder then enters the magnetic separation device for magnetic separation to obtain high-grade concentrated ore powder.

[0042] Among them, the high-temperature exhaust gas discharged from the crushing and pulverizing device enters the heating medium airway of the heat exchanger, the reducing gas from the upper part of the furnace chamber of the suspended magnetized roasting furnace enters the cyclone collector from the outlet of the suspended magnetized roasting furnace, the mineral powder separated by the cyclone collector enters the magnetic separation device, the reducing gas separated by the cyclone collector enters the heated medium airway of the heat exchanger, the high-temperature exhaust gas and the reducing gas exchange heat in the heat exchanger, and then the high-temperature exhaust gas enters the first circulation fan for recycling, the reducing gas enters the Venturi washing tower for washing, and then enters the second circulation fan for recycling.

[0043] <Example 2>

[0044] The composition of the raw ore to be processed is shown in the following table:

[0045]

[0046] The above-mentioned raw ore to be processed is processed by the low-grade refractory iron ore immersion suspension magnetization roasting system in Application Example 1 and the following low-grade refractory iron ore immersion suspension magnetization roasting process, and the process includes the following steps:

[0047] (1) Raw material crushing and powder making: crush the raw ore to less than 200 mesh.

[0048] (2) Roasting and reduction: After being purged, the roasting furnace is filled with reducing gas H2, and the furnace pressure of the roasting furnace is controlled to 0.8MPa. The flue gas circulation component and the gas radiation tube are started to raise the temperature of the roasting furnace to about 570℃. The material enters the roasting furnace from the top distribution device of the roasting furnace. The material is preheated and reduced during the falling process. The temperature in the furnace is controlled to be 570℃, and the reduction time is 30s. The material is fully reduced.

[0049] (3) The reducing gas H2 is discharged from the top of the furnace. After gas-solid separation, it is flashed in a heat exchanger to reduce pressure and temperature, and then passes through a Venturi scrubber to remove moisture from the gas. The purified gas returns to the roasting furnace to participate in the reduction reaction.

[0050] (4) The material falls out of the heating zone of the roasting furnace and enters the lower cooling zone. In the cooling zone, it is fully contacted with the purified reducing gas and cooled, and is discharged from the roasting furnace when it is cooled to below 120°C.

[0051] (5) After reduction and cooling, the ore powder is subjected to two-stage magnetic separation: the first stage has a magnetic field strength of 1800Oe; the second stage has a grinding fineness of -0.045mm accounting for 65.63%, and a magnetic field strength of 1200Oe. Magnetic separation is used to recover iron powder. The total iron content of the product reaches 89.82%, and the recovery rate is 85.86%.

[0052] <Example 3>

[0053] The composition of the raw ore to be processed is shown in the following table:

[0054]

[0055] The above-mentioned raw ore to be processed is processed by the low-grade refractory iron ore immersion suspension magnetization roasting system in Application Example 1 and the following low-grade refractory iron ore immersion suspension magnetization roasting process, and the process includes the following steps:

[0056] (1) Raw material crushing and powder making: crush the raw ore to less than 200 mesh.

[0057] (2) Roasting and reduction: After being purged, the roasting furnace is filled with reducing gas H2, and the furnace pressure of the roasting furnace is controlled to be normal pressure (slightly positive pressure 5-10Pa). The flue gas circulation component and the gas radiation tube are started, and the temperature of the roasting furnace is raised to about 570°C. The material enters the roasting furnace from the top distribution device of the roasting furnace. The material is preheated and reduced during the falling process. The temperature in the furnace is controlled to be 570°C, and the reduction time is 15s. The material is fully reduced.

[0058] (3) The reducing gas H2 is discharged from the top of the furnace, and after gas-solid separation, it is cooled by a heat exchanger, and then the moisture in the gas is removed by a venturi scrubber. The purified gas returns to the roasting furnace to participate in the reduction reaction.

[0059] (4) The material falls out of the heating zone of the roasting furnace and enters the lower cooling zone. In the cooling zone, it is fully contacted with the purified reducing gas and cooled, and is discharged from the roasting furnace when it is cooled to below 120°C.

[0060] (5) After reduction and cooling, the iron ore powder is recovered by magnetic separation. The total iron content of the product reaches 63.06% and the recovery rate is 73.10%.

[0061] <Example 4>

[0062] The composition of the raw ore to be processed is shown in the following table:

[0063]

[0064] (1) Raw material crushing and powder making: crush the raw ore to less than 1mm.

[0065] (2) Roasting and reduction: After being purged, the roasting furnace is filled with reducing gas H2, and the furnace pressure of the roasting furnace is controlled to be 0.8MPa. The flue gas circulation component and the gas radiation tube are started to raise the temperature of the roasting furnace to about 650℃. The material enters the roasting furnace from the top distribution device of the roasting furnace. The material is preheated and reduced during the falling process. The temperature in the furnace is controlled to be 650℃, and the reduction time is 60s. The material is fully reduced.

[0066] (3) The reducing gas H2 is discharged from the top of the furnace, and after gas-solid separation, it is cooled by a heat exchanger, and then the moisture in the gas is removed by a venturi scrubber. The purified gas returns to the roasting furnace to participate in the reduction reaction.

[0067] (4) The material falls out of the heating zone of the roasting furnace and enters the lower cooling zone. In the cooling zone, it is fully contacted with the purified reducing gas and cooled, and is discharged from the roasting furnace when it is cooled to below 120°C.

[0068] (5) After reduction and cooling, the iron ore is subjected to two-stage grinding and magnetic separation. The first stage grinding concentration is 67%, the first stage grinding fineness is more than 80% of -200 mesh, and the first stage magnetic field strength is 2500oe; the second stage grinding fineness is more than 90% of -200 mesh, and the second stage magnetic field strength is 2500oe. The total iron content of the product can reach 65.49%, and the recovery rate can reach 85.9%.

[0069] <Comparative Example 1>

[0070] This comparative example applies the ore composition and process flow in Example 3, except that the reduction temperature in the roasting furnace is increased to 820°C. The iron ore powder after reduction cooling is recovered by magnetic separation. The total iron content of the product is reduced from 63.06% to 58.6%, and the recovery rate is reduced from 73.10% to 69.2%. This result is due to the increase in the reduction temperature from 570°C to 820°C, the iron ore is over-reduced, and part of the ferroferric oxide is converted into weakly magnetic ferrous oxide, resulting in a decrease in recovery rate and grade.

[0071] <Comparative Example 2>

[0072] This comparative example applies the ore composition and process flow in Example 5, and only the roasted material particle size is crushed to 3mm. The iron ore after reduction and cooling is subjected to two-stage grinding and magnetic separation, the first stage grinding concentration is 67%, the first stage grinding fineness is more than 80% of -200 mesh, and the first stage magnetic field strength is 2500oe; the second stage grinding fineness is more than 90% of -200 mesh, and the second stage magnetic field strength is 2500oe. The total iron content of the product can only reach 51.30%, and the recovery rate can only reach 61%. Due to the large material particles, the same reduction time causes no reduction inside the particles, the reduction is uneven, and the first stage magnetic separation rate is low.

[0073] In addition, high working pressure in the roasting furnace means high concentration of reducing gas, which is conducive to the reduction reaction of iron ore and improves the magnetization effect. However, when the working gas pressure in the roasting furnace is higher than 0.8Mpa, it will bring equipment adaptation problems to iron ore feeding, reducing gas supplementation, reducing gas cooling, purification and other links.

[0074] In traditional fluidized bed roasting, low-grade ores with a certain fineness are suspended and stirred in a fluidized bed roasting furnace under the action of an ascending airflow with a certain fluidization velocity, thereby undergoing magnetized roasting. Fluidized bed roasting furnaces are mainly suitable for iron ores with a particle size of 0 to 3 mm. The traditional fluidized bed roasting process uses H2 and CO as reducing agents to increase the iron grade of 45.2% of the original ore to 59.6%. my country's fluidized bed roasting furnace magnetization roasting uses coal gas reduction, and industrial experiments can obtain iron concentrates with a grade of 57% to 65%, with an iron recovery rate of 87% to 96%. Due to the coarse particle size of the raw materials, the single fluidized bed roasting furnace has problems such as high heat energy consumption for roasting rate, long roasting reaction time, slow reduction rate, and uneven reduction, which affect the sorting.

[0075] It is not difficult to see from the above embodiments that the roasting furnace of the present invention adopts powder feeding into the furnace, and the powder is suspended under the action of the airflow and fully contacted with the reducing gas for reduction, which can realize indirect heating of the roasting furnace, so that only reducing gas and reduction products are ensured in the roasting furnace, and there is no destruction of the atmosphere in the furnace by combustion exhaust gas. The material is fed into the furnace from the top of the furnace, and fluidization boiling is not required, which greatly reduces power consumption;

[0076] The magnetization roasting process of the present invention adopts indirect heating by radiant tubes, and the fuel types are wide. The temperature requirements in the furnace can be guaranteed by external heating, and the degree of magnetization can be controlled more accurately; indirect heating does not require heat storage for the iron ore entering the furnace, and the temperature stability and the consistent reduction depth can be guaranteed throughout the reduction process;

[0077] The present invention adopts a process of separating fuel and reducing gas, which can reduce the non-process consumption of reducing gas. And through the design of the circulation system, the reducing gas can be fully utilized;

[0078] The working pressure of the magnetized roasting furnace of the present invention is normal pressure to 0.8Mpa. Compared with the traditional roasting shaft furnace, the working pressure can be increased to increase the concentration of reducing gas, increase the reduction speed, and improve the efficiency; by increasing the circulation rate of reducing gas, the concentration of reaction gas can be stabilized in the whole reaction process, and the uniformity of reduction can be ensured;

[0079] The temperature and gas concentration in the roasting furnace of the present invention are stable, the mineral powder and the reducing gas move in opposite directions, and the optimal process conditions are achieved in the heating zone of the roasting furnace, thereby ensuring the reduction depth. In the traditional process, the fuel gas drives the raw materials to suspend and move in the same direction. When the material temperature is low, the reducing gas concentration is high, and when the material temperature is high, the reducing gas concentration is low and the waste gas concentration is high, which seriously restricts the reduction reaction.

[0080] The invention is a fine-grained iron ore roasting process, which has a wide range of raw material adaptability, does not require processes such as lump ore and pelletizing, uses hydrogen as a reducing gas, and does not generate pollution such as greenhouse gases.

[0081] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. An immersed suspension magnetic roasting system for low-grade refractory iron ore, comprising a crushing and pulverizing device, a suspension magnetic roasting furnace and a magnetic separation device connected in sequence, characterized in that: The feed inlet of the suspension magnetization roasting furnace is arranged at the top of the suspension magnetization roasting furnace, and the discharge port is arranged at the bottom of the suspension magnetization roasting furnace. The suspension magnetization roasting furnace is a low-pressure airtight equipment. The upper part of the furnace cavity of the suspension magnetization roasting furnace adopts gas radiation tube to supply heat to form a heating zone, and the lower part of the furnace cavity of the suspension magnetization roasting furnace is a cooling zone; The system further comprises: a flue gas circulation component and a reducing gas circulation component; The flue gas circulation assembly comprises: a first circulation fan, a heat exchanger and a smoke exhaust fan, the air inlet of the first circulation fan is connected to the air outlet of the gas radiation tube, the air outlet of the first circulation fan is connected to the air inlet of the crushing and pulverizing device, the air outlet of the crushing and pulverizing device is connected to the heating medium inlet of the heat exchanger, the heating medium outlet of the heat exchanger is connected to the air inlet of the first circulation fan, and the air outlet of the crushing and pulverizing device is also connected to the air inlet of the smoke exhaust fan; The reducing gas circulation component includes: a second circulating fan, a cyclone collector, the heat exchanger, and a venturi washing tower. An air inlet of the second circulating fan is connected to the reducing gas delivery pipeline, and an air outlet of the second circulating fan is connected to the air inlet of the suspended magnetization roasting furnace. The air inlet of the suspended magnetization roasting furnace is arranged at the lower part of the furnace chamber of the suspended magnetization roasting furnace, the air outlet of the suspended magnetization roasting furnace is connected to the air inlet of the cyclone collector, and the air outlet of the suspended magnetization roasting furnace is arranged at the top of the suspended magnetization roasting furnace. The air outlet of the cyclone collector is connected to the heated medium inlet of the heat exchanger, the heated medium outlet of the heat exchanger is connected to the air inlet of the venturi washing tower, the air outlet of the venturi washing tower is connected to another air inlet of the second circulating fan, and the discharge port of the cyclone collector is connected to the feed port of the magnetic separation device.

2. A low-grade refractory iron ore immersion suspension magnetic roasting process applied to the low-grade refractory iron ore immersion suspension magnetic roasting system as claimed in claim 1, characterized in that: include: The iron ore is fed into the crushing and pulverizing device for crushing and pulverizing; Passing gas into the gas radiation tube to radiate heat to the upper part of the furnace chamber of the suspension magnetization roasting furnace through gas combustion; The high-temperature flue gas discharged from the gas-fired radiation tube is sucked by the first circulating fan and passed into the crushing and powder-making device to dry and air-select the mineral powder; The ore powder processed by the crushing and powder making device enters the suspension magnetization roasting furnace from the feed port of the suspension magnetization roasting furnace and falls under the action of gravity, and the reducing gas introduced into the suspension magnetization roasting furnace by the second circulation fan flows from the lower part of the furnace chamber of the suspension magnetization roasting furnace into the upper part of the furnace chamber and suspends the ore powder, so that the ore powder is suspended and magnetized roasted in the upper part of the furnace chamber of the suspension magnetization roasting furnace, and the ore powder is reduced by the reducing gas; The reduced ore powder continues to fall under the action of gravity, enters the lower part of the furnace chamber of the suspension magnetic roasting furnace, and contacts with the reducing gas that has just entered the suspension magnetic roasting furnace. The two perform heat exchange, so that the reduced ore powder is cooled, and the reducing gas that has just entered the suspension magnetic roasting furnace is preheated. The cooled ore powder then enters the magnetic separation device for magnetic separation to obtain high-grade concentrated ore powder. Among them, the high-temperature exhaust gas discharged from the crushing and pulverizing device enters the heating medium airway of the heat exchanger, the reducing gas from the upper part of the furnace chamber of the suspended magnetized roasting furnace enters the cyclone collector from the outlet of the suspended magnetized roasting furnace, the mineral powder separated by the cyclone collector enters the magnetic separation device, the reducing gas separated by the cyclone collector enters the heated medium airway of the heat exchanger, the high-temperature exhaust gas and the reducing gas exchange heat in the heat exchanger, and then the high-temperature exhaust gas enters the first circulation fan for recycling, the reducing gas enters the Venturi washing tower for washing, and then enters the second circulation fan for recycling.

3. The low-grade refractory iron ore immersion suspension magnetization roasting process according to claim 2, characterized in that: The iron ore is processed into a particle size of less than 1 mm in the crushing and pulverizing device.

4. The low-grade refractory iron ore immersion suspension magnetization roasting process according to claim 2, characterized in that: The working gas pressure in the suspension magnetization roasting furnace is normal pressure to 0.8 MPa, the maximum reduction temperature is 800° C., and the reduction time of the ore powder in the magnetization roasting furnace is 8 to 60 seconds.

5. The low-grade refractory iron ore immersion suspension magnetization roasting process as claimed in claim 4, characterized in that: The optimum reduction temperature in the suspended magnetization roasting furnace is 570°C.

6. The low-grade refractory iron ore immersion suspension magnetization roasting process according to claim 2, characterized in that: The fuel gas is one of natural gas, converter gas, blast furnace gas, coal-to-gas and hydrogen.

7. The low-grade refractory iron ore immersion suspension magnetization roasting process according to claim 6, characterized in that: The fuel gas is hydrogen.

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