Coal-based suspension roasting device and process for treating siderite and hematite

Abstract

The application relates to a device and process for treating siderite and hematite by adopting coal-based suspension roasting, and belongs to the technical field of mineral processing suspension roasting. The device comprises a lump coal combustion unit, a combustion heat exchange unit, a feeding and grinding unit, a preheating, dust removal and desulfurization unit, an R01 reaction unit, a cooling and waste heat recovery unit and a nitrogen production and supply unit. The lump coal combustion unit is connected with the combustion heat exchange unit; the combustion heat exchange unit is connected with the feeding and grinding unit; the feeding and grinding unit is connected with the preheating, dust removal and desulfurization unit; the preheating, dust removal and desulfurization unit is connected with the R01 reaction unit; the R01 reaction unit is connected with the cooling and waste heat recovery unit; the R01 reaction unit is connected with the nitrogen production and supply unit; the process is simple, can dispose of siderite, hematite (limonite), carbon-containing gold ore, red mud and other mineral resources, thereby improving the economic value of the development and utilization of the resources, and opening up a new way for efficient magnetization roasting of the resources.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing suspension roasting technology, specifically relating to a device and process for treating siderite and hematite using coal-based suspension roasting. Background Technology

[0002] my country possesses abundant iron ore reserves, but these resources are generally characterized by being poor, fine-grained, and complex, often requiring complex beneficiation processes for utilization due to their low endowment, low grade, and difficulty in processing. With the rapid development of my country's steel industry, the demand for iron ore has increased significantly, and the dependence on imported iron ore will continue to rise. Therefore, strengthening research on the efficient development and utilization of complex and difficult-to-process iron ore in China is of significant strategic importance for improving the self-sufficiency rate of iron ore.

[0003] Siderite and hematite are both weakly magnetic, low-grade iron ores, belonging to complex and difficult-to-process iron ore resources. Currently, common processing technologies for weakly magnetic, low-grade iron ores include single high-intensity magnetic separation processes (vertical ring high-intensity magnetic separators, horizontal ring high-intensity magnetic separators, and drum-type high-intensity magnetic separators); single gravity separation processes (spiral sluices, shaking tables, etc.); single flotation processes (direct flotation, reverse flotation); and combined processes (gravity separation-high-intensity magnetic separation, centrifuge-high-intensity magnetic separation, high-intensity magnetic separation-reverse flotation, gravity separation-high-intensity magnetic separation-reverse flotation, etc.). These processes generally suffer from low concentrate grade, high tailings grade, and low recovery rate due to their complex mineral composition, fine crystal size, and susceptibility to mud formation, resulting in low resource utilization efficiency. Therefore, efficiently utilizing siderite and hematite resources to reduce dependence on imported iron ore is urgently needed.

[0004] Siderite is an iron carbonate. Based on its unique thermal decomposition characteristics, roasting it under an inert gas or weakly reducing atmosphere releases CO2 from the ore, significantly improving its grade. Simultaneously, the magnetism of the iron minerals is significantly enhanced, while the magnetism of the gangue minerals remains largely unchanged. The CO produced during decomposition can act as a reducing agent for hematite, converting the weakly magnetic Fe2O3 phase into the strongly magnetic Fe3O4 phase. This allows for efficient material separation through a simple weak magnetic separation process, greatly improving grade and recovery rate, and achieving efficient resource utilization. Extensive research and production practice have shown that magnetic roasting is the optimal method for processing this type of iron ore. Therefore, this invention, targeting the thermal decomposition characteristics of siderite, designs a new suspension roasting process for processing siderite and hematite. This simplifies and streamlines the processing flow of siderite and hematite, making it more efficient and providing an effective way to efficiently utilize siderite and hematite resources, maximizing their resource value. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a device and process for treating siderite and hematite using coal-based suspension roasting. To achieve the above objectives, this invention provides the following technical solution: This invention discloses a coal-based suspension roasting device for treating siderite and hematite, comprising a lump coal combustion unit, a combustion heat exchange unit, a feeding and grinding unit, a preheating, dust removal, and desulfurization unit, an RO1 reaction unit, a cooling waste heat recovery unit, and a nitrogen production and supply unit. The lump coal combustion unit is connected to the combustion heat exchange unit; the combustion heat exchange unit is connected to the feeding and grinding unit; the feeding and grinding unit is connected to the preheating, dust removal, and desulfurization unit; the preheating, dust removal, and desulfurization unit is connected to the RO1 reaction unit; the RO1 reaction unit is connected to the cooling waste heat recovery unit; and the RO1 reaction unit is connected to the nitrogen production and supply unit. The lump coal combustion unit includes a speed-regulating coal feeder and a combustion furnace; the speed-regulating coal feeder is connected to the combustion furnace; the combustion heat exchange unit includes a combustion chamber, a heat exchanger, heat exchange tubes, and a double flap valve; the double flap valve is located below the combustion chamber; the combustion chamber is connected to the heat exchanger; the heat exchanger is equipped with heat exchange tubes; the combustion furnace is connected to the combustion chamber; the feeding and grinding unit includes a raw ore bin, an electronic belt scale, a screw feeder, and a high-temperature dry powder mill; the raw ore bin is connected to the electronic belt scale; the electronic belt scale is connected to the screw feeder; the screw feeder is connected to the high-temperature dry powder mill. The heat exchanger outlet flue gas duct is connected to the high-temperature dry powder mill; the preheating, dust removal, and desulfurization unit includes a cyclone preheater, a bag filter, an induced draft fan, and a desulfurization exhaust tower; the cyclone preheater is connected to the bag filter; the bag filter is connected to the induced draft fan; the induced draft fan is connected to the desulfurization exhaust tower; the outlet of the high-temperature dry powder mill is connected to the inlet of the cyclone preheater; the RO1 reaction unit includes an RO1 reactor, a material air valve, an airlock valve, a cyclone separator, a high-temperature bag filter, a high-temperature centrifugal blower, and an exhaust regulating valve; the RO1 reactor is connected to the cyclone separator via the material air valve and the airlock valve. The separator is connected; the cyclone separator is connected to the high-temperature bag filter; the high-temperature bag filter is connected to the high-temperature centrifugal blower; the high-temperature centrifugal blower is connected to the combustion chamber; the feed pipe of the cyclone preheater and the ash discharge pipe of the bag filter are connected to the feed inlet of the R01 reactor; the heat exchanger is connected to the R01 reactor; the outlet flue of the high-temperature bag filter is connected to the inlet flue of the induced draft fan; an exhaust regulating valve is provided between the high-temperature bag filter and the induced draft fan; the cooling waste heat recovery unit includes cyclone cooler I, cyclone cooler II, cyclone cooler III, and a slurry mixing tank; Cyclone cooler I is connected to cyclone cooler II; cyclone cooler II is connected to cyclone cooler III; cyclone cooler III is connected to the slurry mixing tank; the airlock valve is connected to the inlet flue of cyclone cooler I; the nitrogen generation and supply unit includes a nitrogen generator, a gas storage tank, and a nitrogen supply regulating valve; the nitrogen generator is connected to the gas storage tank; the gas storage tank is connected to the nitrogen supply regulating valve pipeline; the outlet flue gas pipeline of the high-temperature centrifugal blower is connected to the nitrogen supply regulating valve pipeline; the high-temperature bag filter dust collector is connected to the outlet pipeline of the gas storage tank through the loose fluidizing gas pipe of the material air valve and the loose fluidizing gas pipe of the airlock valve.

[0006] A coal-based suspension roasting process for treating siderite and hematite, using the aforementioned apparatus, specifically includes the following steps: Step 1: The raw ore material is fed into the electronic belt scale through the raw ore bin for weighing and measurement, and then fed into the high temperature dry powder mill (34) by the screw feeder. Step 2: The lump coal combustion unit provides the heat required for the reaction to the combustion heat exchange unit, the preheating dust removal and desulfurization unit, and the RO1 reaction unit; Step 3: The preheated air from the waste heat recovery unit after reverse heat exchange is mixed and burned with the fuel gas provided by the lump coal combustion unit in the combustion chamber. The high-temperature flue gas generated heats the lower-temperature gas circulating in the heat exchange tube to generate hot air, which provides a heat source for the R01 reactor. The high-temperature flue gas generated after combustion in the combustion chamber comes into contact with the heat exchange tube from bottom to top and is cooled down. The low-temperature flue gas is discharged from the top of the heat exchange tube to provide preheating for the high-temperature dry powder mill and cyclone preheater. Step 4: The small amount of fine-particle solid material separated by the cyclone preheater is transported to the R01 reactor after being dusted by the bag filter. Step 5: The negative pressure of the system is provided by the induced draft fan. The flue gas after dust removal by the bag filter is transported to the desulfurization exhaust tower by the induced draft fan and discharged into the atmosphere after desulfurization meets the standards. Step 6: The material processed by the high-temperature dry powder mill is preheated by the cyclone preheater and then sent to the R01 reaction unit to provide reaction heat for the R01 reactor; the lower part of the R01 reactor is equipped with a gas chamber for introducing fluidizing gas. Step 7: The material processed by reactor R01 passes through the feed air valve and the airlock valve, and is cooled by nitrogen atmosphere before being sent to the cooling waste heat recovery unit. Nitrogen provides loose fluidizing air for the feed air valve and the airlock valve. The gaseous products, fluidizing gas and dust generated by the thermal decomposition reaction of the material in reactor R01 are filtered by a cyclone separator, and then the flue gas is filtered by a high-temperature bag filter and then sent to the combustion heat exchange unit by a high-temperature centrifugal blower. The hot flue gas after heat exchange provides reaction heat for reactor R01. The dust collected by the high-temperature bag filter is sent to the cooling waste heat recovery unit through a gravity flap valve. The dust recovered by the cyclone separator is returned to reactor R01. Step 8: The material flowing out of the airlock valve undergoes three-stage cyclone cooling through the waste heat recovery unit; cold air flows in the opposite direction to exchange heat with the material, and the cold air passes sequentially through the slurry mixing tank, cyclone cooler III, cyclone cooler II, and cyclone cooler I. The hot air after heat exchange provides combustion air for the combustion chamber. Step 9: The nitrogen generated by the nitrogen generator in the nitrogen supply unit provides loose fluidizing air to the material air valve and the airlock valve, and also provides the blowing air source for the high-temperature bag filter. The air source pressure is 0.4-0.6MPa. The nitrogen supply regulating valve provides initial nitrogen to the R01 reaction unit to purge the R01 reaction unit system with nitrogen, replacing the air in the system. The purging air is discharged through the exhaust regulating valve. After creating an inert atmosphere for the system, the nitrogen supply regulating valve and the exhaust regulating valve are closed. The raw ore material mentioned in step 1 includes siderite, or a mixture of siderite and hematite; when the raw ore material is a mixture of siderite and hematite, the mass percentage of siderite in the mixture is 30% to 60%. The raw ore mentioned in step 1 has a moisture content of no more than 8% and a particle size of no more than 10 mm. The high-temperature dry powder mill mentioned in step 1 operates at a temperature of 300-500℃. After the material is ground by the high-temperature dry powder mill, the mass content of the particle size of -200 mesh is 30%-60%, and the maximum particle size after grinding does not exceed 1mm. The heat provided by the lump coal combustion unit in step 2 comes from the direct combustion of lump coal for heating, or from the combustion of natural gas or coal gas in the configured burner for heating. The coal gas includes one of the following: producer gas, coke oven gas, blast furnace gas, and coal gas producer gas. The combustion chamber temperature of the combustion heat exchange unit in step 2 is 800-1000℃, the cyclone preheater of the preheating dust removal and desulfurization unit operates at 200-300℃, and the RO1 reactor of the RO1 reaction unit operates at 500-750℃. The temperature of the low-temperature flue gas after contact with the heat exchange tube and cooling in step 3 is 300-500℃; The inlet temperature of the bag filter in step 4 is 120–240°C; In step 6, the inlet pressure of the fluidizing gas is not less than 25 kPa, the inlet temperature is 700–950 °C, and the inlet time is 7–12 min; the thermal decomposition reaction temperature of the material is 500–750 °C. The nitrogen atmosphere cooling in step 7 is to reduce the temperature to 350–400°C; the fluidizing air volume of the material air valve and the airlock valve is 10–40 Nm³. 3 / h; the air supply pressure of the airlock valve is 0.2~0.6MPa; the inlet temperature of the high-temperature bag filter is 300~400℃; the dust collected is a qualified product; The three-stage cyclone cooling described in step 8 is to cool the temperature from 350-400℃ to 100-150℃. The nitrogen supply regulating valve mentioned in step 9 is only opened when the furnace is started.

[0007] In the process of the above-mentioned device, the atmosphere is independently self-circulating. After the system atmosphere is saturated, the excess gas can be discharged by regulating and controlling the exhaust regulating valve 57. During normal production, the exhaust regulating valve 57 is in the closed state. The in-situ self-magnetizing roasting system of this invention utilizes the unique thermal decomposition characteristics of siderite. Roasting under an inert gas or weakly reducing atmosphere causes CO2 to decompose from the ore and generates some CO reducing gas, greatly improving the ore grade. At the same time, the magnetism of iron minerals is significantly enhanced, while the magnetism of gangue minerals remains largely unchanged. Thus, efficient material separation can be achieved through a simple weak magnetic separation process. The system atmosphere is independently self-circulating. After the system atmosphere is saturated, excess gas can be discharged through a regulating valve. During normal production, the regulating valve is in the closed state. After thermal decomposition, the magnetite is rapidly cooled with cold air. By precisely controlling the cooling rate, a "micro-oxidation" reaction is controlled on the surface of the magnetite to generate γ-Fe2O3, avoiding oxidation to the weakly magnetic α-Fe2O3. The characteristics of γ-Fe2O3, such as low specific magnetic susceptibility and low coercivity, are utilized to improve the selectivity of roasted products. At the same time, the heat of oxidation reaction and the waste heat of materials can be used to preheat the air, reducing energy consumption. In the process of this invention, during the in-situ reduction roasting of the siderite-hematite system, siderite and hematite play a mutually promoting role, thereby achieving the effect of siderite inducing the in-situ reduction of hematite without adding a reducing agent. Compared with the prior art, the beneficial effects of the present invention are: 1) A new process for processing siderite and hematite resources that efficiently combines and improves technologies such as coal fluidization, direct heating, indirect heat exchange, dry pulverization, in-situ self-magnetization in an oxygen-free environment, and suspension fluidization roasting. The process is simplified, quick and efficient, and can overturn and replace traditional complex and long-process processes such as magnetic separation and flotation. 2) Compared with traditional magnetic and levitation long-process processing, the process method of this invention has a smaller footprint, lower investment and production costs, and significant benefits; 3) The process flow of the present invention is short, flexible and reliable, and is not limited by geographical conditions, water shortage environment, etc., and can be widely applied to different regional environments; 4) The process method of the present invention has a much better process index, such as concentrate grade and metal recovery rate than the traditional magnetic and flotation long process.

[0008] 5) The process method of the present invention improves the economic value of the development and utilization of such resources, and opens up new avenues for the development and efficient utilization of carbonate iron ore and hematite (brown iron) refractory oxide iron ore.

[0009] 6) The process method of the present invention can not only efficiently utilize siderite resources, siderite and hematite (brown iron) in a certain ratio, but also process resources such as shale coal vanadium ore, carbonaceous gold ore, and red mud, and has multiple functions such as in-situ self-magnetizing roasting, oxidative crystal breaking roasting, and hydrogen-based magnetizing roasting. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the process flow structure of a coal-based suspension roasting device for treating siderite and hematite according to the present invention. Attached reference numerals: 11. Variable speed coal feeder; 12. Combustion furnace; 21. Combustion chamber; 22. Heat exchanger; 23. Heat exchange tube; 24. Double flap valve; 31. Raw ore bin; 32. Electronic belt scale; 33. Screw feeder; 34. High-temperature dry powder mill; 41. Cyclone preheater; 42. Bag filter; 43. Exhaust fan; 44. Desulfurization exhaust tower; 51. RO1 reactor; 52. Material air valve; 53. Airlock valve; 54. Cyclone separator; 55. High-temperature bag filter; 56. High-temperature centrifugal blower; 57. Exhaust regulating valve; 61. Cyclone cooler I; 62. Cyclone cooler II; 63. Cyclone cooler III; 64. Pulping and mixing tank; 71. Nitrogen generator; 72. Gas storage tank; 73. Nitrogen supply regulating valve. Detailed Implementation

[0011] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0012] To facilitate understanding of the present invention, a more comprehensive description of the invention will be given below with reference to the accompanying drawings, and several embodiments of the invention will be provided. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the invention will be more thorough and complete.

[0013] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0015] This invention discloses a coal-based suspension roasting device for treating siderite and hematite, comprising a lump coal combustion unit, a combustion heat exchange unit, a feeding and grinding unit, a preheating, dust removal, and desulfurization unit, an RO1 reaction unit, a cooling waste heat recovery unit, and a nitrogen production and supply unit. The lump coal combustion unit is connected to the combustion heat exchange unit; the combustion heat exchange unit is connected to the feeding and grinding unit; the feeding and grinding unit is connected to the preheating, dust removal, and desulfurization unit; the preheating, dust removal, and desulfurization unit is connected to the RO1 reaction unit; the RO1 reaction unit is connected to the cooling waste heat recovery unit; and the RO1 reaction unit is connected to the nitrogen production and supply unit. The lump coal combustion unit includes a speed-regulating coal feeder (11) and a combustion furnace (12); the speed-regulating coal feeder (11) is connected to the combustion furnace (12); the combustion heat exchange unit includes a combustion chamber (21), a heat exchanger (22), heat exchange tubes (23), and a double flap valve (24); the double flap valve (24) is provided below the combustion chamber (21); the combustion chamber (21) is connected to the heat exchanger (22); the heat exchanger (22) is provided with heat exchange tubes (23); the combustion furnace (12) is connected to the combustion chamber (21); the feeding and grinding unit includes a raw ore bin (31), an electronic belt scale (32), a screw feeder (33), and a high-temperature dry grinding mill (34); the raw ore bin (31) is connected to the electronic belt scale (32). The electronic belt scale (32) is connected to the screw feeder (33); the screw feeder (33) is connected to the high-temperature dry powder mill (34); the flue gas duct at the outlet of the heat exchanger (22) is connected to the high-temperature dry powder mill (34); the preheating, dust removal and desulfurization unit includes a cyclone preheater (41), a bag filter (42), an induced draft fan (43), and a desulfurization exhaust tower (44); the cyclone preheater (41) is connected to the bag filter (42); the bag filter (42) is connected to the induced draft fan (43); the induced draft fan (43) is connected to the desulfurization exhaust tower (44); the outlet of the high-temperature dry powder mill (34) is connected to the inlet of the cyclone preheater (41); the R01 reaction unit includes an R01 reactor (51), a material air valve ( 52), airlock valve (53), cyclone separator (54), high-temperature bag filter (55), high-temperature centrifugal blower (56), exhaust regulating valve (57); R01 reactor (51) is connected to cyclone separator (54) through material air valve (52) and airlock valve (53); cyclone separator (54) is connected to high-temperature bag filter (55); high-temperature bag filter (55) is connected to high-temperature centrifugal blower (56); the high-temperature centrifugal blower (56) is connected to combustion chamber (21); the feed pipe of cyclone preheater (41) and the ash discharge pipe of bag filter (42) are connected to feed inlet of R01 reactor (51); heat exchanger 22 is connected to R01 reactor (51); the high-temperature bag filter (55) The outlet flue is connected to the inlet flue of the induced draft fan (43); an exhaust regulating valve (57) is provided between the high-temperature bag filter (55) and the induced draft fan (43); the cooling waste heat recovery unit includes cyclone cooler I (61), cyclone cooler II (62), cyclone cooler III (63), and slurry mixing tank (64); the cyclone cooler I (61) is connected to the cyclone cooler II (62); the cyclone cooler II (62) is connected to the cyclone cooler III (63); the cyclone cooler III (63) is connected to the slurry mixing tank (64); the airlock valve (53) is connected to the inlet flue of the cyclone cooler I (61); the nitrogen generation and supply unit includes a nitrogen generator (71), a gas storage tank (72), and a nitrogen supply regulating valve (73);The nitrogen generator (71) is connected to the gas storage tank (72); the gas storage tank (72) is connected to the nitrogen supply regulating valve (73) via a pipeline; the outlet flue gas pipeline of the high-temperature centrifugal blower (56) is connected to the nitrogen supply regulating valve (73) via a pipeline; the high-temperature bag filter (55) is connected to the outlet pipeline of the gas storage tank (72) via the loose fluidizing gas pipe of the material air valve (52) and the loose fluidizing gas pipe of the airlock valve (53).

[0016] The process method using the above-described apparatus includes the following steps: Step 1: The raw ore material is fed into the electronic belt scale (32) through the raw ore bin (31) for weighing and measurement, and then fed into the high temperature dry powder mill (34) by the screw feeder (33); Step 2: The lump coal combustion unit provides the heat required for the reaction to the combustion heat exchange unit, the preheating dust removal and desulfurization unit, and the RO1 reaction unit; Step 3: The preheated air from the reverse heat exchange unit and the fuel gas provided by the lump coal combustion unit are mixed and burned in the combustion chamber (21). The high-temperature flue gas generated heats the lower-temperature gas circulating in the heat exchange tube (23) to generate hot air, which provides a heat source for the R01 reactor (51). The high-temperature flue gas generated after combustion in the combustion chamber (21) comes into contact with the heat exchange tube (23) from bottom to top and the cooled low-temperature flue gas is discharged from the top of the heat exchange tube (23) to provide preheating for the high-temperature dry powder mill (34) and the cyclone preheater (41). Step 4: The small amount of fine-particle solid material separated by the cyclone preheater (41) is transported to the R01 reactor (51) after being removed by the bag filter (42). Step 5: The negative pressure of the system is provided by the induced draft fan (43). The flue gas after dust removal by the bag filter (42) is transported to the desulfurization exhaust tower (44) by the induced draft fan (43) and discharged into the atmosphere after desulfurization meets the standards. Step 6: The material processed by the high-temperature dry powder mill (34) is preheated by the cyclone preheater (41) and then sent to the R01 reaction unit to provide reaction heat for the R01 reactor; the lower part of the R01 reactor (51) is equipped with a gas chamber to introduce fluidizing gas. Step 7: The material processed by the R01 reactor (51) passes through the material air valve (52) and the airlock valve (53), and is cooled by nitrogen atmosphere before being sent to the cooling waste heat recovery unit. Nitrogen provides loose fluidizing air for the material air valve (52) and the airlock valve (53). The gaseous products, fluidizing gas and dust generated by the thermal decomposition reaction of the material in the R01 reactor (51) are removed by the cyclone separator (54). After being removed by the high-temperature bag filter (55), the flue gas is sent to the combustion heat exchange unit by the high-temperature centrifugal blower (56). The hot flue gas after heat exchange provides reaction heat for the R01 reactor (51). The dust removed by the high-temperature bag filter (55) is sent to the cooling waste heat recovery unit through the gravity flap valve. The dust recovered by the cyclone separator (54) is returned to the R01 reactor. Step 8: The material flowing out from the airlock valve (53) undergoes three-stage cyclone cooling through the waste heat recovery unit; cold air flows in the opposite direction to exchange heat with the material, and the cold air passes sequentially through the slurry mixing tank (64), cyclone cooler III (63), cyclone cooler II (62), and cyclone cooler I (61). The hot air after heat exchange provides combustion air for the combustion chamber (21). Step 9: The nitrogen generated by the nitrogen generator (71) in the nitrogen supply unit provides loose fluidizing air to the material air valve (52) and the airlock valve (53), and provides a blow air source to the high-temperature bag filter (55). The air source pressure is 0.4-0.6 MPa. The nitrogen supply regulating valve (73) provides initial nitrogen to the R01 reaction unit, purges the R01 reaction unit system with nitrogen, replaces the air in the system, and discharges the purging gas through the exhaust regulating valve (57). After creating an inert atmosphere for the system, the nitrogen supply regulating valve (73) and the exhaust regulating valve (57) are closed.

[0017] The raw ore material mentioned in step 1 includes siderite, or a mixture of siderite and hematite; when the raw ore material is a mixture of siderite and hematite, the mass percentage of siderite in the mixture is 30% to 60%. The raw ore mentioned in step 1 has a moisture content of no more than 8% and a particle size of no more than 10 mm. The high-temperature dry grinding mill (34) mentioned in step 1 operates at a temperature of 300-500℃. After the material is ground by the high-temperature dry grinding mill (34), the mass content of the particle size of -200 mesh is 30%-60%, and the maximum particle size after grinding does not exceed 1mm. The heat provided by the lump coal combustion unit in step 2 comes from the direct combustion of lump coal for heating, or from the combustion of natural gas or coal gas in the configured burner for heating. The coal gas includes one of the following: producer gas, coke oven gas, blast furnace gas, and coal gas producer gas. The temperature of the combustion chamber (21) of the combustion heat exchange unit in step 2 is 800-1000℃, the working temperature of the cyclone preheater (41) of the preheating dust removal and desulfurization unit is 200-300℃, and the working temperature of the R01 reactor of the R01 reaction unit is 500-750℃. The temperature of the low-temperature flue gas after contact with the heat exchange tube (23) and cooling in step 3 is 300-500℃; The inlet temperature of the bag filter (42) mentioned in step 4 is 120-240℃; In step 6, the inlet pressure of the fluidizing gas is not less than 25 kPa, the inlet temperature is 700–950 °C, and the inlet time is 7–12 min; the thermal decomposition reaction temperature of the material is 500–750 °C. The nitrogen atmosphere cooling in step 7 is to reduce the temperature to 350-400℃; the fluidizing air volume of the material air valve (52) and the airlock valve (53) is 10-40 Nm³. 3 / h; the air supply pressure of the airlock valve (53) is 0.2-0.6MPa; the inlet temperature of the high-temperature bag filter (55) is 300-400℃; the dust collected is a qualified product; The three-stage cyclone cooling described in step 8 is to cool the temperature from 350-400℃ to 100-150℃. The nitrogen supply regulating valve (73) mentioned in step 9 is only opened when the furnace is started.

[0018] Example 1: Roasting of siderite alone The schematic diagram of the process flow structure of this invention is as follows: Figure 1 As shown, the TFe grade of siderite is 43.83%. Siderite begins thermal decomposition to produce CO2 at around 400℃, and CO production begins at 460℃. 630℃ is the optimal temperature for CO production; above 630℃, CO production decreases. Simultaneously, with increasing reaction temperature, the maximum decomposition rate of siderite continuously increases and the time of occurrence shifts earlier, indicating that the thermal decomposition reaction of siderite accelerates with increasing temperature. Above 630℃, unfavorable factors dominate. Furthermore, the change in CO flow rate in the gaseous components of siderite thermal decomposition also reflects the reaction process of FeO, an intermediate product, being magnetized into Fe3O4. Between 460℃ and 720℃, with increasing temperature, the rate of FeO to Fe3O4 conversion initially increases rapidly and then the rate of increase slows slightly, but the overall magnetic conversion rate initially increases and then decreases, reaching its peak at 630℃.

[0019] Example 2: Siderite-induced reduction roasting of hematite The results of reduction roasting of the siderite-hematite system were obtained under the following conditions: siderite content 30%, roasting temperature 700℃, roasting time 8 min. Under these conditions, a magnetic concentrate grade of 66.61% and a recovery rate of 95.33% were achieved. Hematite particle size significantly influenced the in-situ reduction of hematite induced by siderite. As the hematite particle size decreased, both the siderite content and reaction time could be reduced, and the saturated magnetic moment per unit mass of the roasted product also decreased accordingly. Compared to roasting of single siderite, the in-situ reduction roasting of the siderite-hematite system containing hematite rapidly consumed the reducing substances (CO, FeO) generated by the thermal decomposition of siderite, accelerating the reaction rate of magnetite formation from siderite (FeO + CO2 → Fe3O4 + CO). Simultaneously, some of the magnetite generated by the rapid decomposition of siderite served as active sites, reducing the difficulty of reducing hematite to magnetite. In the in-situ reduction roasting of the siderite-hematite system, siderite and hematite play a mutually promoting role, thereby achieving the effect of siderite inducing the in-situ reduction of hematite without the addition of a reducing agent.

[0020] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An apparatus for treating siderite and hematite using coal-based suspension roasting, characterized in that, The system includes a lump coal combustion unit, a combustion heat exchange unit, a feeding and grinding unit, a preheating, dust removal, and desulfurization unit, an RO1 reaction unit, a cooling waste heat recovery unit, and a nitrogen production and supply unit. The lump coal combustion unit is connected to the combustion heat exchange unit; the combustion heat exchange unit is connected to the feeding and grinding unit; the feeding and grinding unit is connected to the preheating, dust removal, and desulfurization unit; the preheating, dust removal, and desulfurization unit is connected to the RO1 reaction unit; the RO1 reaction unit is connected to the cooling waste heat recovery unit; and the RO1 reaction unit is connected to the nitrogen production and supply unit. The lump coal combustion unit includes a speed-regulating coal feeder (11) and a combustion furnace (12); the speed-regulating coal feeder (11) is connected to the combustion furnace (12); the combustion heat exchange unit includes a combustion chamber (21), a heat exchanger (22), heat exchange tubes (23), and a double flap valve (24); the double flap valve (24) is provided below the combustion chamber (21); the combustion chamber (21) is connected to the heat exchanger (22); the heat exchanger (22) is provided with heat exchange tubes (23); the combustion furnace (12) is connected to the combustion chamber (21); the feeding and grinding unit includes a raw ore bin (31), an electronic belt scale (32), a screw feeder (33), and a high-temperature dry grinding mill (34); the raw ore bin (31) and the electronic belt scale (32) are connected to each other. The electronic belt scale (32) is connected to the screw feeder (33); the screw feeder (33) is connected to the high-temperature dry powder mill (34); the flue gas duct at the outlet of the heat exchanger (22) is connected to the high-temperature dry powder mill (34); the preheating, dust removal and desulfurization unit includes a cyclone preheater (41), a bag filter (42), an induced draft fan (43), and a desulfurization exhaust tower (44); the cyclone preheater (41) is connected to the bag filter (42); the bag filter (42) is connected to the induced draft fan (43); the induced draft fan (43) is connected to the desulfurization exhaust tower (44); the outlet of the high-temperature dry powder mill (34) is connected to the inlet of the cyclone preheater (41); the R01 reaction unit includes an R01 reactor (5 1) Material air valve (52), airlock valve (53), cyclone separator (54), high-temperature bag filter (55), high-temperature centrifugal blower (56), exhaust regulating valve (57); The R01 reactor (51) is connected to the cyclone separator (54) through the material air valve (52) and airlock valve (53); The cyclone separator (54) is connected to the high-temperature bag filter (55); The high-temperature bag filter (55) is connected to the high-temperature centrifugal blower (56); The high-temperature centrifugal blower (56) is connected to the combustion chamber (21); The feed pipe of the cyclone preheater (41) and the ash discharge pipe of the bag filter (42) are connected to the feed inlet of the R01 reactor (51); The outlet flue of the high-temperature bag filter (55) The high-temperature bag filter (55) is connected to the inlet flue of the induced draft fan (43); an exhaust regulating valve (57) is provided between the high-temperature bag filter (55) and the induced draft fan (43); the cooling waste heat recovery unit includes cyclone cooler I (61), cyclone cooler II (62), cyclone cooler III (63), and slurry mixing tank (64); cyclone cooler I (61) is connected to cyclone cooler II (62); cyclone cooler II (62) is connected to cyclone cooler III (63); cyclone cooler III (63) is connected to slurry mixing tank (64); the airlock valve (53) is connected to the inlet flue of cyclone cooler I (61); the nitrogen generation and supply unit includes a nitrogen generator (71), a gas storage tank (72), and a nitrogen supply regulating valve (73);The nitrogen generator (71) is connected to the gas storage tank (72); the gas storage tank (72) is connected to the nitrogen supply regulating valve (73) via a pipeline; the outlet flue gas pipeline of the high-temperature centrifugal blower (56) is connected to the nitrogen supply regulating valve (73) via a pipeline; the high-temperature bag filter (55) is connected to the outlet pipeline of the gas storage tank (72) via the loose fluidizing gas pipe of the material air valve (52) and the loose fluidizing gas pipe of the airlock valve (53).

2. A process for treating siderite and hematite using coal-based suspension roasting, employing the apparatus as described in claim 1, characterized in that, Includes the following steps: Step 1: The raw ore material is fed into the electronic belt scale (32) through the raw ore bin (31) for weighing and measurement, and then fed into the high temperature dry powder mill (34) by the screw feeder (33); Step 2: The lump coal combustion unit provides the heat required for the reaction to the combustion heat exchange unit, the preheating dust removal and desulfurization unit, and the RO1 reaction unit; Step 3: The preheated air from the reverse heat exchange unit and the fuel gas provided by the lump coal combustion unit are mixed and burned in the combustion chamber (21). The high-temperature flue gas generated heats the lower-temperature gas circulating in the heat exchange tube (23) to generate hot air, which provides a heat source for the R01 reactor (51). The high-temperature flue gas generated after combustion in the combustion chamber (21) comes into contact with the heat exchange tube (23) from bottom to top and the cooled low-temperature flue gas is discharged from the top of the heat exchange tube (23) to provide preheating for the high-temperature dry powder mill (34) and the cyclone preheater (41). Step 4: The small amount of fine-particle solid material separated by the cyclone preheater (41) is transported to the R01 reactor (51) after being removed by the bag filter (42). Step 5: The negative pressure of the system is provided by the induced draft fan (43). The flue gas after dust removal by the bag filter (42) is transported to the desulfurization exhaust tower (44) by the induced draft fan (43) and discharged into the atmosphere after desulfurization meets the standards. Step 6: The material processed by the high-temperature dry powder mill (34) is preheated by the cyclone preheater (41) and then sent to the R01 reaction unit to provide reaction heat for the R01 reactor (51); the lower part of the R01 reactor (51) is equipped with a gas chamber to introduce fluidizing gas. Step 7: The material processed by the R01 reactor (51) is cooled by nitrogen atmosphere through the material air valve (52) and the air lock valve (53) and then sent to the cooling waste heat recovery unit. Nitrogen provides loose fluidizing air for the material air valve (52) and the air lock valve (53). The gaseous products, fluidizing gas and dust generated by the thermal decomposition reaction of the material in the R01 reactor (51) are removed by the cyclone separator (54). After being removed by the high temperature bag filter (55), the flue gas is sent to the combustion heat exchange unit by the high temperature centrifugal blower (56). The hot flue gas after heat exchange provides reaction heat for the R01 reactor (51). The dust removed by the high temperature bag filter (55) is sent to the cooling waste heat recovery unit through the gravity flap valve. The dust recovered by the cyclone separator (54) is returned to the R01 reactor (51). Step 8: The material flowing out from the airlock valve (53) undergoes three-stage cyclone cooling through the waste heat recovery unit; cold air flows in the opposite direction to exchange heat with the material, and the cold air passes through the slurry mixing tank (64), cyclone cooler III (63), cyclone cooler II (62), and cyclone cooler I (61) in sequence. The hot air after heat exchange provides combustion air for the combustion chamber (21). Step 9: The nitrogen generated by the nitrogen generator (71) in the nitrogen supply unit provides loose fluidizing air to the material air valve (52) and the airlock valve (53), and provides a blow air source for the high-temperature bag filter (55). The air source pressure is 0.4-0.6 MPa. The nitrogen supply regulating valve (73) provides initial nitrogen to the R01 reaction unit, purges the R01 reaction unit system with nitrogen, replaces the air in the system, and discharges the purging gas through the exhaust regulating valve (57). After creating an inert atmosphere for the system, the nitrogen supply regulating valve (73) and the exhaust regulating valve (57) are closed.

3. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, The raw material in step 1 is siderite, or a mixture of siderite and hematite; when the raw material is a mixture of siderite and hematite, the mass percentage of siderite in the mixture is 30% to 60%; the moisture content of the raw ore is not higher than 8%, and the particle size is not higher than 10 mm; the working temperature of the high-temperature dry grinding mill (34) is 300 to 500°C, and the mass content of the material after grinding by the high-temperature dry grinding mill (34) is 30% to 60% of the particle size of -200 mesh, and the maximum particle size after grinding is not more than 1 mm.

4. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, The heat provided by the lump coal combustion unit in step 2 comes from the direct combustion of lump coal for heating, or from the combustion of natural gas or coal gas in the configured burner for heating. The coal gas includes one of producer gas, coke oven gas, and blast furnace gas. The temperature of the combustion chamber (21) of the combustion heat exchange unit is 800-1000℃, the working temperature of the cyclone preheater (41) of the preheating dust removal and desulfurization unit is 200-300℃, and the working temperature of the R01 reactor (51) of the R01 reaction unit is 500-750℃.

5. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, The temperature of the low-temperature flue gas after contact with the heat exchange tube (23) in step 3 is 300-500℃.

6. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, The inlet temperature of the bag filter (42) mentioned in step 4 is 120-240℃.

7. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, In step 6, the inlet pressure of the fluidizing gas should not be less than 25 kPa, the inlet temperature should be 700–950 °C, and the inlet time should be 7–12 min; the thermal decomposition reaction temperature of the material should be 500–750 °C.

8. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, The nitrogen atmosphere cooling in step 7 is to reduce the temperature to 350-400℃; the fluidizing air volume of the material air valve (52) and the airlock valve (53) is 10-40 Nm³. 3 / h; the air supply pressure of the airlock valve (53) is 0.2 to 0.6 MPa; the inlet temperature of the high-temperature bag filter (55) is 300 to 400℃; the dust collected is a qualified product.

9. The process for treating siderite and hematite using coal-based suspension roasting according to claim 2, characterized in that, The three-stage cyclone cooling described in step 8 is cooling from 350-400℃ to 100-150℃; the nitrogen supply regulating valve (73) described in step 9 is only opened when the furnace is started.

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