Coal-based magnetization reduction roasting treatment equipment and method for red mud

Abstract

The invention relates to coal-based magnetization, reduction and roasting treatment equipment and method for red mud, and belongs to the technical field of comprehensive utilization of industrial waste residue resources, pulverized coal is adopted as a red mud magnetization and roasting treatment reducing agent, and reduction and oxidation reaction is performed after drying, crushing and preheating treatment, so that reduction, magnetization and roasting treatment of ferric oxide in the red mud is completed. Iron oxide (Fe2O3) contained in the red mud is converted into magnetic iron oxide (Fe3O4) through a reduction-oxidation reaction, and iron element substances are magnetically separated through water quenching and cooling treatment, so that refined iron ore powder with the TFe grade being 58-60% on average is obtained. By means of the system process method, the average recovery rate of metal iron in the red mud can reach 90% or above. And the magnetization reduction roasting temperature is controlled at 700-800 DEG C. The equipment is low in energy consumption, safe and reliable in operation, high in production capacity, free of pollution and capable of realizing large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of industrial waste slag resources, and specifically relates to a coal-based magnetization reduction roasting treatment device and method for red mud. Background Art

[0002] Red mud is an industrial waste produced in the production of electrolytic aluminum. Red mud contains a large amount of metal elements such as iron and aluminum, among which iron has the highest proportion among the many metal elements contained. However, since iron exists in the form of iron oxide (Fe2O3), it is difficult to separate, extract and recycle. Therefore, how to effectively separate and extract iron has become the main engineering and technical problem for the comprehensive utilization of red mud waste resources.

[0003] At present, the existing magnetic reduction roasting magnetic separation iron extraction process is considered to be one of the most effective technical means in the red mud iron extraction technology. Using gas-based (CO or H2) or coal-based (coal powder or coke powder) as a reducing agent to carry out magnetic reduction roasting of red mud has become the main direction of project research and development in this engineering field. In the existing public related technologies, both gas-based reduction and coal-based reduction red mud magnetic reduction roasting processes have some engineering and technical problems and shortcomings. In the magnetic reduction roasting process with gas-based reduction, the promotion of this technology is limited due to the fact that the gas-based (CO or H2) reducing gas requires a special gas source, and the production process is strictly controlled and the process is complex. Coal-based reduction magnetic roasting is mostly pressed into balls with batch coal, and the reduction roasting is carried out at high temperature (1300-1400℃) for several hours. The roasting products need to be crushed, the production energy consumption is large, and the equipment operation failures are many, which hinder the application of this technology. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a coal-based magnetic reduction roasting treatment device and method for red mud, that is, a method for recovering the iron element contained in red mud and corresponding process equipment. The method uses red mud as a production raw material and coal powder as a reducing agent. After the red mud raw material is dried, crushed, and preheated, it is subjected to low-temperature magnetic reduction roasting at 700-800°C. After the roasting product is cooled by water quenching, it is sent to a magnetic separation system for separation and extraction of magnetic iron oxide to obtain a fine iron ore powder product with a TFe grade of 58-60%.

[0005] The technical solution of the present invention is as follows:

[0006] A coal-based magnetic reduction roasting treatment device for red mud, comprising a red mud drying and crushing device, a preheating device, a reduction magnetic roasting device and a water quenching cooling device;

[0007] The red mud drying and crushing device is used to dry and crush the raw red mud into powder, and comprises a red mud dryer, a red mud raw material feeder and a bag-type gas-solid separation receiver connected by pipelines;

[0008] The preheating device is used for preheating the dried red mud powder, and comprises a red mud powder preheater, a red mud powder feeder and a preheater hot air furnace;

[0009] The reduction magnetization roasting device is used to preheat the powder material and the coal powder reducing agent for magnetization reduction roasting, and includes a reduction magnetization roasting furnace, a homogenization material feeder, a coal powder feeder, a homogenizer, a coal powder batching machine and a roasting furnace hot air furnace;

[0010] The water quenching cooling device is used for performing water quenching cooling treatment on the products of the magnetization reduction roasting furnace, and comprises a water quenching cooling water tank.

[0011] Furthermore, the red mud dryer is an airflow dryer with a disintegrating mechanical device and a classifier. The heat for drying and dehydrating the red mud raw material comes from the gas discharged from the red mud powder preheater. The carrier gas discharged from the red mud dryer is separated by a bag-type gas-solid separation receiver, and the separated dry powder enters the red mud powder preheater for preheating through the red mud powder feeder, and the separated tail gas is discharged through the system induced draft fan.

[0012] Furthermore, the red mud powder preheater is an internally heated rotary preheater. The material preheating heat mainly comes from the hot flue gas generated by the gas hot blast furnace equipped with the preheater. At the same time, the tail gas discharged by the reduction magnetization roasting furnace enters the hot blast furnace equipped for the red mud powder preheater as secondary air distribution.

[0013] Furthermore, the reduction magnetization roasting furnace is an externally heated rotary roasting furnace. The heat for the material reduction magnetization roasting comes from the hot flue gas generated by the gas hot blast furnace equipped in the roasting furnace, and is provided by conductive heating. The coal powder feeder, coal powder batching machine, homogenized material feeder and homogenizer are respectively used for coal powder grinding, quantitative batching, homogenization of coal powder and preheated materials, and feeding the homogenized materials to the roasting furnace.

[0014] The present invention also provides a method for treating red mud by using coal-based magnetization reduction roasting, which is implemented by using the above-mentioned red mud by using coal-based magnetization reduction roasting equipment, and comprises the following steps:

[0015] (1) The raw material is fed into the red mud raw material feeder, and the raw material is dried, crushed, and classified by the red mud dryer to process the water-containing red mud filter cake raw material into a powder material without free water;

[0016] (2) The material-carrying gas discharged from the dryer is separated by a bag-type gas-solid separation receiver, and the powder material enters the red mud powder preheater through the red mud powder feeder. The red mud powder preheater is used to preheat the dry powder into preheated material; the heat for material preheating mainly comes from the hot flue gas generated by the hot air furnace of the preheater;

[0017] (3) using a reduction magnetization roasting furnace to carry out magnetization reduction roasting treatment on the homogenized preheated material and the proportioned coal powder, and using the coal powder reducing agent to magnetize and reduce the iron oxide in the preheated material to a roasted material of magnetic iron oxide under high temperature;

[0018] (4) Using a water quenching cooling device, the roasted material is oxygen-free cooled to obtain a magnetically separated material.

[0019] In the step (1), the red mud raw material has a moisture content of 15% and an iron content of 40-50%.

[0020] In the step (1), the air inlet temperature of the red mud dryer is 350-450°C, and the drying, crushing and classification particle size is 200-300 mesh.

[0021] The red mud powder preheater in step (2) has an air inlet temperature of 450-550° C. The red mud powder preheater is an internally heated rotary preheater, or other types of preheaters.

[0022] In the step (3), the coal powder reducing agent is anthracite powder, the fixed carbon content of which is greater than 80wt%, the coal powder particle size is 180-200 mesh, and the mass of the coal powder is 5-13% of the mass of the red mud preheated dry powder.

[0023] In the step (3), the calcination temperature in the reduction magnetization calcination furnace is 700-800° C., and the reduction time is 20-50 minutes.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. The present invention proposes a method and equipment for treating red mud by magnetic reduction roasting with coal as the reducing agent, that is, a magnetic roasting method for red mud with coal powder as the reducing agent. The method is to first dry the red mud filter cake, crush and grade it into dry powder, and then homogenize it with the reducing agent coal powder after preheating, and then send it to the magnetic reduction roasting furnace to complete the magnetic reduction roasting oxidation reaction of red mud iron oxide to magnetic iron oxide. Since the materials involved in the reaction are all fine powders with large specific surface areas, the magnetic reduction reaction of the materials is sufficient and rapid under the heat of the roasting furnace. The iron oxide (Fe2O3) contained in the red mud can complete the magnetic reduction reaction to generate magnetic iron oxide (Fe2O3) or a small amount of iron (Fe), and the yield of iron substances in the red mud can reach an ideal effect of more than 90%.

[0026] 2. The coal-based red mud magnetization reduction roasting process of the present invention determines the red mud magnetization reduction reaction process and control conditions. In a roasting furnace with a roasting temperature of 700-800°C and a roasting time of 20-50min, the material reaction temperature and time are greatly reduced compared to the roasting temperature of 1280-1350°C and the roasting process time of 4.5-5h corresponding to the red mud coal-based pressed ball magnetization reduction roasting process, thereby fundamentally avoiding many technical problems such as the roasting material adhering to the equipment due to high temperature and long time. Compared with the gas-based red mud magnetization reduction roasting process, the process of the present invention does not require a gaseous reducing agent, so the system operation and equipment operation of the present invention are more reliable and easy.

[0027] 3. In the process of the present invention, the red mud filter cake is dried and dehydrated by a red mud dryer. Since the dryer is equipped with a mechanical scattering and classifier device, the material can be effectively dried, crushed and classified under the action of hot air and scattering mechanical force and the control of the classifier. The powder preheating and reduction magnetization roasting treatment respectively adopt an internal heating rotary preheater and an external heating rotary roasting furnace, and the material running speed in the furnace is adjusted to meet the process requirements of the dry powder preheating and the magnetization reduction reaction of the preheated powder and the reducing agent coal powder.

[0028] 4. The tail gas discharged from the red mud preheater of the present invention enters the red mud dryer as a heat source for drying the red mud raw materials. The tail gas discharged from the reduction magnetization roasting furnace enters the hot air furnace configured for the red mud powder preheater as secondary air distribution. The process system of the present invention realizes the full utilization of heat in stages to improve the thermal efficiency of the system and minimize the system production energy consumption and production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the process flow of a red mud coal-based magnetized reduction roasting treatment equipment system of the present invention. Among them: 1-bag-type gas-solid separation receiver; 2-red mud dryer; 3-red mud raw material feeder; 4-red mud powder feeder; 5-red mud powder preheater; 6-preheater hot air furnace; 7-reduction magnetized roasting furnace; 8-homogenizer; 9-homogenized material feeder; 10-coal powder batching machine; 11-roasting furnace hot air furnace; 12-water quenching cooling water tank. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and process system advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the content of the present invention.

[0031] like Figure 1As shown, a red mud coal-based magnetized reduction roasting treatment equipment includes: a red mud drying and crushing device, a preheating device, a reduction magnetized roasting device and a water quenching cooling device; the red mud drying and crushing device is used to dry and crush the raw red mud into powder, including a red mud dryer 2, a red mud raw material feeder 3 and a bag-type gas-solid separation receiver 1 connected by pipelines; the preheating device is used to preheat the red mud dry powder, including a red mud powder preheater 5, a red mud powder feeder 4 and a preheater hot air furnace 6; the reduction magnetized roasting device is used to preheat the powder and carry out magnetized reduction roasting with a coal powder reducing agent, including a reduction magnetized roasting furnace 7, a homogenizer 8, a coal powder feeder, a homogenized material feeder 9, a coal powder batching machine 10 and a roasting furnace hot air furnace 11; the water quenching cooling device is used to carry out water quenching cooling treatment on the product of the magnetized reduction roasting furnace, including a water quenching cooling water tank 12. The feed port of the red mud dryer 2 is connected to the discharge port of the red mud raw material feeder 3; the air inlet and outlet of the red mud dryer 2 are respectively connected to the air outlet of the red mud powder preheater 5 and the air inlet of the bag-type gas-solid separation receiver 1 through pipelines; the feed port and discharge port of the red mud powder feeder 4 are respectively connected to the discharge port of the bag-type gas-solid separation receiver 1 and the feed port of the red mud powder preheater 5 through pipelines; the air inlet and discharge port of the red mud powder preheater 5 are respectively connected to the air outlet of the preheater hot air furnace 6 and the feed port of the homogenizing material feeder 9 through pipelines; the feed port of the homogenizing material feeder 9 is also connected to the discharge port of the coal powder batching machine 10; the discharge port of the homogenizing material feeder 9 is connected to the feed port of the homogenizer 8.

[0032] The feed inlet and discharge port of the reduction magnetization roasting furnace 7 are respectively connected to the discharge port of the homogenizer 8 and the feed inlet of the water quenching cooling water tank 12; the air inlet and air outlet of the reduction magnetization roasting furnace 7 are respectively connected to the air outlet of the roasting hot air furnace 11 and the air distribution port of the preheater hot air furnace 6 through pipelines.

[0033] The red mud treatment method based on the above-mentioned treatment equipment using coal-based magnetization reduction roasting comprises the following steps:

[0034] (1) Red mud drying, crushing and classification

[0035] The red mud with a water content of 15% and an iron content of 48% is quantitatively fed into the red mud dryer 2 through the red mud raw material feeder 3. Under the action of the tail gas from the red mud powder preheater 5 and the dispersing device in the dryer, the raw material is dried, dispersed, crushed and classified. The preheated tail gas temperature, i.e., the air temperature at the dryer inlet, is 400°C. The moisture content of the dried red mud is below 1%, and the material is dried into a powder material, and the powder particle size is classified into 230 meshes.

[0036] (2) Powder preheating

[0037] The material-carrying gas discharged from the dryer is separated into gas and solid by the bag-type gas-solid separation receiver 1, and the separated dry material is sent to the red mud powder feeder 4, and then sent to the red mud powder preheater 5 by the feeder. The red mud powder preheater 5 adopts an internal heating rotary preheater to realize material preheating under the action of the hot gas running in the preheater; specifically, the material is preheated by the mixed action of the combustion flue gas of the preheater hot blast furnace 6 and the tail gas (secondary air) from the reduction magnetization roasting furnace 7, and the material runs in the opposite direction of the airflow. The hot gas (mixed gas) wind temperature is controlled at 700℃, and the material preheating temperature reaches 350℃. The material running time is 35min.

[0038] (3) Mixing and homogenization

[0039] The preheated powder is discharged from the discharge port of the red mud powder preheater 5 and sent to the homogenizing material feeder 9 to merge with the coal powder sent from the coal powder batching machine 10 into the feeder. The fixed carbon content of the coal powder is greater than 80wt.%. Then, the feeder sends it to the material homogenizer 8 for mixing and homogenization. The mass of the coal powder is 8% of the mass of the red mud preheated dry powder.

[0040] (4) Magnetization reduction roasting

[0041] The homogenized mixed powder is sent into the reduction magnetization roasting furnace 7, which is an externally heated rotary roasting furnace. The powder magnetization reduction reaction temperature is 750°C and the operation time is 40 minutes. The red mud magnetization reduction roasting material is discharged from the tail of the roasting furnace and enters the water quenching cooling device.

[0042] (5) Water quenching

[0043] The red mud magnetized reduction material is sent to the water quenching cooling device for oxygen-free water quenching cooling treatment.

[0044] The cooled magnetized reduced material is sent to the magnetic separation system to collect the iron ore concentrate, the TFe grade of the iron ore concentrate is 60%, and the iron yield in the red mud is 95%.

Claims

1. A coal-based magnetic reduction roasting treatment device for red mud, characterized in that: The invention comprises a red mud drying and crushing device, a preheating device, a reduction magnetization roasting device and a water quenching cooling device; the red mud drying and crushing device is used to dry and crush the raw material red mud into powder, and comprises a red mud dryer (2), a red mud raw material feeder (3) and a bag-type gas-solid separation receiver (1) connected by pipelines; the preheating device is used to preheat the dried red mud powder, and comprises a red mud powder preheater (5), a red mud powder feeder (4) and a preheater hot air furnace (6); the reduction magnetization roasting device is used to preheat the powder and carry out magnetization reduction roasting with a coal powder reducing agent, and comprises a reduction magnetization roasting furnace (7), a homogenization material feeder (9), a coal powder feeder, a homogenizer (8), a coal powder batching machine (10) and a roasting furnace hot air furnace (11); the water quenching cooling device is used to carry out water quenching cooling treatment on the product of the magnetization reduction roasting furnace, and comprises a water quenching cooling water tank (12).

2. The coal-based magnetic reduction roasting treatment equipment for red mud according to claim 1 is characterized in that: The red mud dryer (2) is an airflow dryer equipped with a breaking mechanism and a classifier; the heat for drying and dehydrating the red mud raw material comes from the gas discharged from the red mud powder preheater (5).

3. The coal-based magnetic reduction roasting treatment equipment for red mud according to claim 1 is characterized in that: The carrier gas discharged from the red mud dryer is separated by a bag-type gas-solid separation receiver (1), the separated dry powder is fed into a red mud powder preheater (5) for preheating treatment through a red mud powder feeder (4), and the separated tail gas is discharged through a system induced draft fan.

4. The coal-based magnetization reduction roasting treatment equipment for red mud according to claim 1, characterized in that: The red mud powder preheater (5) is an internally heated rotary preheater. The heat for preheating the material mainly comes from the hot flue gas generated by the gas hot blast furnace (6) equipped with the preheater. At the same time, the tail gas discharged by the reduction magnetization roasting furnace (7) enters the hot blast furnace (6) equipped for the red mud powder preheater (5) as secondary air supply.

5. The coal-based magnetization reduction roasting treatment equipment for red mud according to claim 1, characterized in that: The reduction magnetization roasting furnace (7) is an externally heated rotary roasting furnace. The heat for the reduction magnetization roasting of the material comes from the hot flue gas generated by the gas hot blast furnace (11) equipped in the roasting furnace, and is provided by conductive heating; the coal powder feeder, coal powder batching machine (10), homogenized material feeder (9) and homogenizer (8) are respectively used for coal powder grinding, quantitative batching, homogenization of coal powder and preheated materials, and feeding the homogenized materials to the roasting furnace.

6. A method for treating red mud by magnetizing reduction and roasting with coal, which is implemented by using the red mud magnetizing reduction and roasting equipment according to any one of claims 1 to 5, characterized in that: The steps include: (1) The raw material is fed into the red mud raw material feeder (3), and the raw material is dried, crushed, and classified by the red mud dryer (2), so that the water-containing red mud filter cake raw material is processed into a powder material without free water; (2) The material-carrying gas discharged from the dryer is separated by a bag-type gas-solid separation receiver (1), and the powder material enters a red mud powder preheater (5) through a red mud powder feeder (4), and the dried powder material is preheated by the red mud powder preheater (5) to become a preheated material; the heat for preheating the material mainly comes from the hot flue gas generated by the hot air furnace (6) of the preheater; (3) using a reduction magnetization roasting furnace (7) to carry out magnetization reduction roasting treatment on the homogenized preheated material and the proportioned coal powder, and using the coal powder reducing agent to magnetize and reduce the iron oxide in the preheated material under the action of high temperature to form a roasted material of magnetic iron oxide; (4) Using a water quenching cooling device, the roasted material is oxygen-free cooled to obtain a magnetically separated material.

7. The method for treating red mud by coal-based magnetization reduction roasting according to claim 6, characterized in that: In the step (1), the air inlet temperature of the red mud dryer is 350-450°C, and the drying, crushing and classification particle size is 200-300 mesh.

8. The method for treating red mud by coal-based magnetization reduction roasting according to claim 6, characterized in that: The red mud powder preheater in step (2) has an air inlet temperature of 450-550°C; the red mud powder preheater used is an internally heated rotary preheater, or other types of preheaters.

9. The method for treating red mud by coal-based magnetization reduction roasting according to claim 6, characterized in that: In the step (3), the coal powder reducing agent is anthracite powder, the fixed carbon content of which is greater than 80wt%, the coal powder particle size is 180-200 mesh, and the mass of the coal powder is 5-13% of the mass of the red mud preheated dry powder.

10. The method for treating red mud by coal-based magnetization reduction roasting according to claim 6, characterized in that: In the step (3), the calcination temperature in the reduction magnetization calcination furnace is 700-800° C., and the reduction time is 20-50 minutes.

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