Iron silicate suspension calcination reduction system and technology

Abstract

The invention discloses an iron silicate suspension calcination reduction system and technology.The suspension calcination reduction system comprises a raw material supply mechanism, a reducing agent supply mechanism, a preheating system, a flue gas treatment mechanism and a suspension calcination reduction kiln, and the raw material supply mechanism comprises supply equipment, a mineral aggregate mill, a sorting machine and a front magnetic separator; the discharging end of the feeding device is connected with a feeding port of the mineral aggregate grinding machine, a discharging port of the mineral aggregate grinding machine is connected with a feeding port of the sorting machine, and a discharging port of the sorting machine is connected with a feeding port of the front magnetic separator. A feeding port of the preheating system is connected with a discharging port of the front magnetic separator, and a discharging port of the preheating system is connected with a feeding port of the suspension calcination reduction kiln. The method has the technical effects that suspension calcination reduction is adopted, the reduction efficiency is high, the reduction time is short, the reduction temperature is stable and controllable, energy is saved, environment is protected, and cost can be reduced and efficiency can be increased; the whole system adopts modular multi-stage integration, and is low in investment cost, low in operation and maintenance cost and simple to operate.

Description

Technical Field

[0001] The invention relates to the technical field of ferric silicate reduction, and in particular to a ferric silicate suspension calcination reduction system and a ferric silicate suspension calcination reduction process. Background Art

[0002] Iron silicate, a general term for iron-containing silicate minerals, is associated with iron ore. Due to its widespread distribution and diverse nature, it is commonly found in various iron ore deposits and smelting slags. Currently, iron silicate is considered an unusable iron-containing mineral. In mineral processing and metallurgical production, it is considered a gangue mineral, making it difficult to utilize industrially and considered a hazardous component. The complexity of the associated assemblages and significant differences in chemical properties of iron silicate minerals make experimental research on iron separation from them challenging.

[0003] Traditional iron oxides can be effectively reduced by magnetization roasting with reducing agents, but ores or smelting slag containing Si-Fe salts cannot achieve effective iron reduction. Smelting slag contains valuable metallic iron, but the embedded particle size is relatively fine, making it difficult to separate and enrich the valuable iron using conventional mineral processing methods for recycling. Iron reduction technology is a global research and development topic, especially the reduction of iron silicate, which is more difficult to achieve. Currently, there are tens of billions of tons of smelting slag solid waste stored in China, including aluminum smelting slag, copper smelting slag, zinc smelting slag, nickel smelting slag, etc. The resources cannot be effectively and comprehensively utilized on an industrial scale, and have problems such as large occupied area, high hazards, and high maintenance costs.

[0004] Iron in tailings and smelting slag occurs primarily in the form of olivine and chromite, with the iron primarily distributed in the fine-grained fraction. These fine-grained iron minerals are difficult to efficiently recover directly from the smelting slag using conventional separation methods such as gravity separation and flotation. Iron-containing olivine-type slags, such as copper slag and nickel slag, primarily consist of iron and silicon, accounting for 35%-50% and 30%-40%, respectively. They also contain significant amounts of copper, cobalt, nickel, and zinc, making them highly valuable resources and economically. Because the iron minerals in these slags or smelting slags are primarily fayalite, followed by smaller magnetite, and because fayalite and magnetite are tightly bound together, they are difficult to separate using conventional grinding-magnetic separation processes. Currently, experimental technologies for efficiently recovering fine-grained iron minerals from smelting slags primarily rely on reduction roasting-magnetic separation, which reduces iron oxides to highly magnetic iron or elemental iron. The roasted product then requires subsequent grinding-magnetic separation to obtain the desired iron concentrate. However, the iron recovery rate is low and the iron grade in the concentrate is low.

[0005] Iron silicate belongs to orthosilicate olivine. In its crystal structure, cations and SiO4 4-After the O atoms of the formed Si-O tetrahedrons are coordinated, they form a Si-O-Me bonding pattern. The valuable metal oxides are encapsulated by layers of silicate, making them acid and alkali resistant and unable to be separated and enriched by physical grinding. The key chemical bond that needs to be broken for the depolymerization of iron silicate is the Me-O bond formed between the metal cation and O, that is, the Si-O or Fe-O bond. Common methods for breaking chemical bonds include high-temperature melting and leaching. However, the high-temperature melting method has high energy consumption, long processing time, and low efficiency, while the leaching method has disadvantages such as unclear targets and secondary pollution.

[0006] Related research indicates that adding an appropriate amount of roasting aid during the smelting slag separation and roasting process facilitates the reduction of iron minerals and the separation and recovery of iron. However, factors such as the amount of roasting aid, the amount of reducing agent, and the reduction temperature and time affect the recovery of iron. Currently, the cost of effective roasting aids used in rotary kilns is higher than the added value of valuable metal recovery.

[0007] At present, the separation technologies of valuable iron include physical separation method and chemical separation method. The physical separation method is derived from the separation method of mineral processing technology, and its main feature is temperature-controlled roasting, which is further divided into metallized reduction roasting, magnetized reduction roasting and oxidative roasting. The reduction roasting procedure is based on the industrial iron minerals under certain temperature conditions and in a suitable reducing atmosphere to reduce and separate the iron oxides that are easily reduced to metallic iron, while the iron-containing silicate minerals are not easily reduced. The chemical separation method is derived from the wet process, through acid leaching. The existing iron reduction technology process scheme is: raw materials → fine grinding → adding roasting aids to mix → adding reducing agents to mix → adding water to granulate / pellet → high-temperature roasting and reduction in a roasting furnace → high-temperature reduced raw materials water quenching → wet fine grinding → wet magnetic separation and enrichment. This process is not suitable for the reduction of iron silicate. Summary of the Invention

[0008] To this end, the present invention provides a ferrous silicate suspension calcination reduction system and process to solve the above-mentioned problems in the prior art.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] According to a first aspect of the present invention, a ferrous silicate suspension calcination reduction system comprises a raw material supply mechanism, a reducing agent supply mechanism, a preheating system, a flue gas treatment mechanism, and a suspension calcination reduction kiln, wherein the raw material supply mechanism comprises a feeding device, an ore mill, a separator, and a pre-magnetic separator, wherein the discharge end of the feeding device is connected to the feed inlet of the ore mill, the discharge port of the ore mill is connected to the feed inlet of the separator, and the discharge port of the separator is connected to the feed inlet of the pre-magnetic separator;

[0011] The feed inlet of the preheating system is connected to the discharge port of the pre-magnetic separator, and the discharge port of the preheating system is connected to the feed inlet of the suspension calcination reduction kiln;

[0012] The preheating system uses the flue gas of the suspension calcination reduction kiln as a heat source. The flue gas of the suspension calcination reduction kiln undergoes heat exchange in the preheating system and then enters the flue gas treatment mechanism for treatment before being discharged.

[0013] The reducing agent supply mechanism includes a solid reducing agent supply mechanism and a gas reducing agent supply mechanism. The discharge end of the solid reducing agent supply mechanism is connected to the solid reducing agent feeding port of the suspension calcination reduction kiln; the gas supply port of the gas reducing agent supply mechanism is connected to the gas reducing agent feeding port of the suspension calcination reduction kiln.

[0014] Furthermore, it also includes a metering mechanism, which is arranged between the raw material supply mechanism and the preheating system.

[0015] Furthermore, the metering mechanism includes a metering conveyor belt and a screw feeder, the loading end of the metering conveyor belt is connected to the discharge port of the front magnetic separator, the unloading end of the metering conveyor belt is connected to the inlet of the screw feeder, and the discharge port of the screw feeder is connected to the inlet of the preheating system.

[0016] Furthermore, the preheating system includes a high-temperature cyclone, a low-temperature cyclone, a preheating cyclone and a preheating dryer;

[0017] The raw material feed port of the preheating dryer is connected to the discharge port of the screw feeder, the discharge port of the preheating dryer is connected to the feed port of the low-temperature cyclone, the gas outlet of the low-temperature cyclone is connected to the flue gas treatment mechanism, and the discharge port of the low-temperature cyclone is connected to the feed port of the preheating cyclone;

[0018] The feed port of the high-temperature cyclone is connected to the discharge port of the suspension calcination reduction kiln, the gas outlet of the high-temperature cyclone is connected to the feed port of the preheating cyclone, the gas outlet of the preheating cyclone is connected to the air inlet of the preheating dryer, and the discharge port of the preheating cyclone is connected to the feed port of the suspension calcination reduction kiln;

[0019] The discharge port of the high-temperature cyclone is connected to the feed port of the cooling cyclone, and the discharge port of the cooling cyclone is connected to the feed port of the post-magnetic separator.

[0020] Furthermore, the gas reducing agent supply mechanism includes an inert gas supply tank and a gas reducing agent supply tank, the gas supply ports of the inert gas supply tank and the gas reducing agent supply tank are both connected to the feed port of the cooling cyclone, and the gas outlet of the cooling cyclone is connected to the gas reducing agent filling port of the suspension calcination reduction kiln.

[0021] Furthermore, it also includes a high-temperature blower, which is arranged between the gas outlet of the cooling cyclone and the gas reducing agent filling port of the suspension calcination reduction kiln.

[0022] Furthermore, the solid reductant supply mechanism includes a solid reductant feeder and a solid reductant silo, the discharge port of the solid reductant silo is connected to the feed port of the solid reductant feeder, and the discharge port of the solid reductant feeder is connected to the solid reductant feeding port of the suspension calcination reduction kiln.

[0023] Furthermore, the flue gas treatment mechanism includes a bag dust collector, an induced draft fan and a chimney, the air inlet of the bag dust collector is connected to the gas outlet of the low-temperature cyclone, the exhaust port of the bag dust collector is connected to the input port of the induced draft fan, and the output port of the induced draft fan is connected to the air inlet of the chimney.

[0024] The present invention has the following advantages: it adopts suspended calcination reduction, has high reduction efficiency, short reduction time, stable and controllable reduction temperature, energy saving and environmental protection, and can reduce costs and increase efficiency; the entire system adopts modular multi-level integration, with low investment cost, low operation and maintenance cost, and simple operation; it can reduce raw ore or smelting slag containing iron silicate, and is suitable for iron tailings powder, zinc slag, copper slag, aluminum slag powder, laterite nickel ore, and can also be iron salts and iron oxides, or valuable metal inorganic salts or their oxides that can be reduced by reducing agents such as carbon, CO, H2 at high temperature.

[0025] According to a second aspect of the present invention, a suspension calcination reduction process for iron silicate employs the suspension calcination reduction system described in the first aspect, including a solid material treatment process and a flue gas treatment process;

[0026] The solid material processing process is as follows: ore and solid roasting aid are added to an ore mill in proportion through a feeding device for crushing; the crushed material is added to a separator for screening; the material with a qualified particle size is screened out and added to a pre-magnetic separator for magnetic separation; the lean iron ore powder is magnetically separated and metered and conveyed to a screw feeder via a metering conveyor belt; the screw feeder is conveyed to a preheating dryer for preheating and drying using flue gas; the dried material and the flue gas are then added to a low-temperature cyclone for separation; the separated material is added to a preheating cyclone for further preheating using flue gas; and the separated material is added to a suspension calcination reduction kiln through a feed inlet to react with a reducing agent using high temperature;

[0027] After the reaction is completed, the reduction products in the suspension calcination reduction kiln are transported together with the flue gas to a high-temperature cyclone for separation. The separated reduction products are then transported to a cooling cyclone for cooling, and finally magnetically separated and enriched by a post-magnetic separator.

[0028] The flue gas treatment process is as follows: hot air is input into the suspension calcination reduction kiln using a hot blast furnace, the reduction product in the suspension calcination reduction kiln is transported together with the flue gas to a high-temperature cyclone for separation, the separated flue gas is input into a preheating cyclone to preheat the solid material, the flue gas after heat exchange is input into a preheating dryer to preheat and dry the solid material, and then the flue gas and the dried solid material are input into a low-temperature cyclone for separation, and finally the separated flue gas is discharged through a chimney after being treated to meet the standards.

[0029] Furthermore, the reducing agent in the solid material processing process includes a solid reducing agent and a gas reducing agent. The solid reducing agent is directly added to the suspension calcination reduction kiln through the solid reducing agent feeding port, and the gas reducing agent is preheated by heat exchange with the reduction product through the cooling cyclone and then added to the suspension calcination reduction kiln through the gas reducing agent gas feeding port.

[0030] The present invention has the following advantages: adopting dry reduction technology (fire reduction technology) and suspension calcination reduction, the suspension fluidization has a large specific surface area, high original efficiency, stable and controllable reduction temperature, energy saving and environmental protection; the reduced material is directly contact-cooled by cold inert gas, the process is simple and easy to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely illustrative, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0032] The structures, proportions, sizes, etc. illustrated in this specification are intended solely to complement the contents disclosed herein and to facilitate understanding and reading by persons skilled in the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall remain within the scope of the technical contents disclosed herein.

[0033] Figure 1 A schematic diagram of the overall structure of a ferrous silicate suspension calcination reduction system provided in some embodiments of the present invention.

[0034] In the figure: 1. Hot blast furnace, 2. Solid reducing agent feeder, 3. Solid reducing agent silo, 4. Preheating cyclone, 5. Suspension calcination reduction kiln, 6. Low-temperature cyclone, 7. Bag dust collector, 8. Induced draft fan, 9. Chimney, 10. Feeding equipment, 11. Mineral mill, 12. Sorting machine, 13. Pre-magnetic separator, 14. Measuring conveyor belt, 15. Screw feeder, 16. Preheating dryer, 17. Inert gas supply tank, 18. Gas reducing agent supply tank, 19. Post-magnetic separator, 20. Cooling cyclone, 21. High-temperature fan, 22. High-temperature cyclone. DETAILED DESCRIPTION

[0035] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0036] Example 1

[0037] like Figure 1 As shown, a ferrous silicate suspension calcination reduction system in an embodiment of the first aspect of the present invention includes a raw material supply mechanism, a reducing agent supply mechanism, a preheating system, a flue gas treatment mechanism and a suspension calcination reduction kiln 5, wherein the raw material supply mechanism includes a feeding device 10, an ore mill 11, a separator 12 and a pre-magnetic separator 13, the discharge end of the feeding device 10 is connected to the feed port of the ore mill 11, the discharge port of the ore mill 11 is connected to the feed port of the separator 12, and the discharge port of the separator 12 is connected to the feed port of the pre-magnetic separator 13;

[0038] The inlet of the preheating system is connected to the outlet of the pre-magnetic separator 13, and the outlet of the preheating system is connected to the inlet of the suspension calcination reduction kiln 5;

[0039] The preheating system uses the flue gas of the suspension calcination reduction kiln 5 as a heat source. After the flue gas of the suspension calcination reduction kiln 5 undergoes heat exchange in the preheating system, it enters the flue gas treatment mechanism for treatment and then is discharged.

[0040] The reducing agent supply mechanism includes a solid reducing agent supply mechanism and a gas reducing agent supply mechanism. The discharge end of the solid reducing agent supply mechanism is connected to the solid reducing agent feeding port of the suspension calcination reduction kiln 5; the gas supply port of the gas reducing agent supply mechanism is connected to the gas reducing agent feeding port of the suspension calcination reduction kiln 5. The suspension calcination reduction kiln 5 can be a single-stage kiln or a multi-stage kiln according to design requirements.

[0041] In this embodiment, it should be noted that a hot blast furnace 1 is further included, and the output end of the hot blast furnace 1 is connected to the air supply port of the suspension calcination reduction kiln 5 to provide a hot air flow into the suspension calcination reduction kiln 5;

[0042] The entire system adopts the solid-state reduction method. Melting is not allowed during the reduction process, otherwise it will cause adhesion between the raw materials or between the raw materials and the equipment, affecting the operation of the system. The reduction temperature should generally be 50℃-100℃ lower than the softening temperature of the raw materials. During the reduction process, the bonding effect should be avoided (some ore powders have a strong tendency to stick together during the reduction process, causing agglomeration. Accompanied by the local chemical reduction of iron ore particles, the degree of reduction on the particle surface is relatively low, generating primary reduced iron, which prompts the particles to weld together, affecting the suspension and fluidized reduction effects).

[0043] Furthermore, the solid reducing agent can be coke powder, carbon powder, gasified coal, fly ash, solid waste with a fixed carbon content greater than 80%, or a mixture thereof as required by the design. The gas reducing agent can be CO, H2, coal gas, or a mixture thereof as required by the design. The chemical reaction formula for the high-temperature reaction of iron silicate, calcium oxide, and carbon monoxide for iron reduction is as follows:

[0044] Fe2(SiO3)3+3CaO+3CO=2Fe+3CaSiO3+3CO2

[0045] 2FeSiO3+2CaO+2CO=2Fe+2CaSiO3+2CO2

[0046] Iron silicate, calcium oxide and carbon react at high temperature. The chemical reaction equation is:

[0047] Fe2(SiO3)3+3CaO+3C=2Fe+3CaSiO3+3CO

[0048] 2FeSiO3+2CaO+C=2Fe+2CaSiO3+CO2

[0049] The technical effects achieved by this embodiment are: suspension calcination reduction is adopted, with high reduction efficiency, short reduction time, stable and controllable reduction temperature, energy saving and environmental protection, and cost reduction and efficiency improvement; the entire system adopts modular multi-level integration, with low investment cost, low operation and maintenance cost, and simple operation; it can reduce raw ore or smelting slag containing iron silicate, and is suitable for iron tailings powder, zinc slag, copper slag, aluminum slag powder, laterite nickel ore, and can also be iron salts and iron oxides, or valuable metal inorganic salts or their oxides that can be reduced by reducing agents such as carbon, CO, H2 at high temperature, and has a wide range of applications.

[0050] Example 2

[0051] like Figure 1As shown, this embodiment provides another iron silicate suspension calcination reduction system, the structure of which includes all the contents of Example 1, and only the different parts are described below.

[0052] In this embodiment, a metering mechanism is further included, and the metering mechanism is arranged between the raw material supply mechanism and the preheating system.

[0053] In this embodiment, it should be noted that the metering mechanism includes a metering conveyor belt 14 and a screw feeder 15. The loading end of the metering conveyor belt 14 is connected to the discharge port of the front magnetic separator 13, the unloading end of the metering conveyor belt 14 is connected to the feed port of the screw feeder 15, and the discharge port of the screw feeder 15 is connected to the feed port of the preheating system. The screw feeder 15 adopts a sealed screw feeder.

[0054] Furthermore, it also includes an intelligent control unit. The raw material supply mechanism, reducing agent supply mechanism, preheating system, flue gas treatment mechanism and metering mechanism are all connected to the intelligent control unit. By setting up the intelligent control unit, automatic control of the system can be achieved; at the same time, a modular desulfurization and denitrification unit can be built into the entire system.

[0055] The technical effect achieved by this embodiment is: by setting a metering mechanism, the material conveying amount can be accurately measured, which facilitates the flexible adjustment of the material supply amount according to actual production needs.

[0056] Example 3

[0057] like Figure 1 As shown, this embodiment provides another iron silicate suspension calcination reduction system, the structure of which includes all the contents of Example 2, and only the different parts are described below.

[0058] In this embodiment, the preheating system includes a high-temperature cyclone 22, a low-temperature cyclone 6, a preheating cyclone 4, and a preheating dryer 16;

[0059] The raw material feed port of the preheating dryer 16 is connected to the discharge port of the screw feeder 15, the discharge port of the preheating dryer 16 is connected to the feed port of the low-temperature cyclone 6, the gas outlet of the low-temperature cyclone 6 is connected to the flue gas treatment mechanism, and the discharge port of the low-temperature cyclone 6 is connected to the feed port of the preheating cyclone 4;

[0060] The feed port of the high-temperature cyclone 22 is connected to the discharge port of the suspension calcination reduction kiln 5, the gas outlet of the high-temperature cyclone 22 is connected to the feed port of the preheating cyclone 4, the gas outlet of the preheating cyclone 4 is connected to the air inlet of the preheating dryer 16, and the discharge port of the preheating cyclone 4 is connected to the feed port of the suspension calcination reduction kiln 5;

[0061] The discharge port of the high-temperature cyclone 22 is connected to the feed port of the cooling cyclone 20, the discharge port of the cooling cyclone 20 is connected to the feed port of the mill, and the discharge port of the mill is connected to the feed port of the post-magnetic separator 19. The mill is used to grind the metallic iron in the reduction product into monomers through grinding.

[0062] In this embodiment, it should be noted that the gas reducing agent supply mechanism includes an inert gas supply tank 17 and a gas reducing agent supply tank 18. The gas supply ports of the inert gas supply tank 17 and the gas reducing agent supply tank 18 are both connected to the feed port of the cooling cyclone 20, and the gas outlet of the cooling cyclone 20 is connected to the gas reducing agent filling port of the suspension calcination reduction kiln 5. The inert gas and the gas reducing agent exchange heat with the reduction product in the cooling cyclone 20. The inert gas can be CO2, N2, oxygen-free flue gas after treatment, or a variety of mixed gases according to design requirements, etc., to cool the reduction product. At the same time, the inert gas and the gas reducing agent are preheated and then enter the suspension calcination reduction kiln 5. The gas reducing agent will be lost after contacting with the high-temperature reduction product in the cooling cyclone 20. In order to ensure the supply amount of the gas reducing agent, it can be appropriately supplemented before it enters the suspension calcination reduction kiln 5. The material before reduction is preheated by direct contact with the hot flue gas, and the material after reduction is cooled by direct contact with the cold inert gas.

[0063] The cooling cyclone 20 plays the role of directly cooling the reduced hot material through cold reducing gas or cold inert gas in an oxygen-free manner. The preheated reducing agent and the reduced hot material are pre-reduced. It can be a single-stage cyclone or a multi-stage cyclone. The cooling cyclone can be replaced by a gas-solid powder flow cooler.

[0064] Furthermore, it also includes a high-temperature fan 21, which is arranged between the gas outlet of the cooling cyclone 20 and the gas reducing agent filling port of the suspension calcination reduction kiln 5. The high-temperature fan 21 is used to provide power to transport the gas reducing agent into the suspension calcination reduction kiln 5.

[0065] The technical effect achieved by this embodiment is: by setting up a preheating system, the heat of the flue gas can be fully utilized to preheat the material and the reduction product can be cooled, so the system energy can be fully utilized, and the entire system is more energy-saving and efficient.

[0066] Example 4

[0067] like Figure 1 As shown, this embodiment provides another iron silicate suspension calcination reduction system, the structure of which includes all the contents of Example 2, and only the different parts are described below.

[0068] In this embodiment, the solid reducing agent supply mechanism includes a solid reducing agent feeder 2 and a solid reducing agent silo 3, the discharge port of the solid reducing agent silo 3 is connected to the feed port of the solid reducing agent feeder 2, and the discharge port of the solid reducing agent feeder 2 is connected to the solid reducing agent feeding port of the suspension calcination reduction kiln 5.

[0069] In this embodiment, it should be noted that the flue gas treatment mechanism includes a bag dust collector 7, an induced draft fan 8 and a chimney 9. The air inlet of the bag dust collector 7 is connected to the gas outlet of the low-temperature cyclone 6, the exhaust port of the bag dust collector 7 is connected to the input port of the induced draft fan 8, the output port of the induced draft fan 8 is connected to the air inlet of the chimney 9, and the chimney 9 is provided with an automatic flue gas monitoring system.

[0070] The technical effect achieved by this embodiment is: by setting up a flue gas treatment mechanism, the flue gas generated by the system can be treated to ensure that the flue gas meets the emission standards and is more environmentally friendly.

[0071] Example 5

[0072] like Figure 1 As shown, a suspension calcination reduction process for iron silicate in an embodiment of the second aspect of the present invention adopts the suspension calcination reduction system of the first aspect, including a solid material treatment process and a flue gas treatment process;

[0073] The solid material processing process is as follows: the ore and the solid roasting aid are added to the ore mill 11 in proportion through the feeding device 10 for crushing, the crushed material is added to the separator 12 for screening, the material with qualified particle size is screened out and added to the pre-magnetic separator 13 for magnetic separation, and the material with unqualified particle size is re-transported to the ore mill 11 for re-crushing; the pre-magnetic separator 13 is used to magnetically separate the enriched iron concentrate and the lean iron ore powder, the lean iron ore powder is metered and transported to the screw feeder 15 by the metering conveyor belt 14, and the screw feeder 15 is transported to the preheating dryer 16 for preheating and drying by flue gas, and then the dried material and the flue gas are added to the low-temperature cyclone 6 for separation, the separated material is added to the preheating cyclone 4 for further preheating by flue gas, and the separated material is added to the suspension calcination reduction kiln 5 through the feed inlet to react with the reducing agent by high temperature;

[0074] After the reaction is completed, the reduction products in the suspension calcination reduction kiln 5 are transported together with the flue gas to the high-temperature cyclone 22 for separation. The separated reduction products are then transported to the cooling cyclone 20 for cooling. Finally, they are magnetically separated by the post-magnetic separator 19 to separate the enriched iron ore concentrate and tailings powder.

[0075] The flue gas treatment process is as follows: hot air is input into the suspension calcination reduction kiln 5 using the hot blast furnace 1, and the reduction product in the suspension calcination reduction kiln 5 is transported together with the flue gas to the high-temperature cyclone 22 for separation, and the separated flue gas is input into the preheating cyclone 4 to preheat the solid material, and the flue gas after heat exchange is input into the preheating dryer 16 to preheat and dry the solid material, and then the flue gas and the dried solid material are input into the low-temperature cyclone 6 for separation, and finally the separated flue gas is treated to meet the standards and discharged through the chimney 9; the flue gas treatment process is as follows: first, the flue gas is dedusted by the bag dust collector, and then the flue gas treatment mechanism in the chimney desulfurizes and denitrifies the flue gas. After treatment, the flue gas is inspected and discharged after meeting the standards.

[0076] In this embodiment, it should be noted that the reducing agent in the solid material processing process includes a solid reducing agent and a gaseous reducing agent. The solid reducing agent is directly added to the suspension calcination reduction kiln 5 through the solid reducing agent feeding port. The gaseous reducing agent is preheated by heat exchange with the reduction product through the cooling cyclone 20 and then added to the suspension calcination reduction kiln 5 through the gaseous reducing agent feeding port. The reducing agent is added as oxygen-free as possible during the addition process, and an oxygen-free state is ensured during the reduction process. The oxygen content affects the reduction effect and wastes the reducing agent.

[0077] Furthermore, the gaseous reducing agent must be mixed with an inert gas before entering the cooling cyclone 20 and introduced into part of the flue gas in the chimney for preheating. Solid roasting aids can be selected from calcium oxide, limestone powder, carbide slag, magnesium oxide, magnesite, urea, or a combination thereof according to design requirements. Calcium-based powders must have a CaO content greater than 60% after high-temperature calcination, and magnesium-based powders must have a MgO content greater than 60% after high-temperature calcination.

[0078] The particle size of the solid reducing material and the solid reducing agent is required to be less than 300 meshes. The temperature range of the ferrous silicate suspension calcination reduction process is wide, and the ferrous silicate reduction can be carried out between 600°C and 1200°C.

[0079] The technical effects achieved by this embodiment are: using dry reduction technology (fire reduction technology) and suspended calcination reduction, the suspended fluidization has a large specific surface area, high original efficiency, stable and controllable reduction temperature, energy saving and environmental protection, and is a simple, efficient, low-pollution, and low-cost solution for treating difficult-to-decompose minerals and solid wastes; the reduced material is directly cooled by cold inert gas, which is an innovative technology with a simple process and easy control. The current reduction technology uses direct water cooling to cool the reduced material, which is complex in process and high in cost.

[0080] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

[0081] The terms "upper", "lower", "left", "right", "middle", etc. used in this specification are only for the convenience of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships should be regarded as within the scope of the present invention without substantially changing the technical content.

Claims

1. A ferrous silicate suspension calcination reduction system, characterized in that: The invention comprises a raw material supply mechanism, a reducing agent supply mechanism, a preheating system, a flue gas treatment mechanism and a suspension calcination reduction kiln (5), wherein the raw material supply mechanism comprises a feeding device (10), an ore mill (11), a separator (12) and a pre-magnetic separator (13), the discharge end of the feeding device (10) is connected to the feed port of the ore mill (11), the discharge port of the ore mill (11) is connected to the feed port of the separator (12), and the discharge port of the separator (12) is connected to the feed port of the pre-magnetic separator (13); The feed inlet of the preheating system is connected to the discharge port of the pre-magnetic separator (13), and the discharge port of the preheating system is connected to the feed inlet of the suspension calcination reduction kiln (5); The preheating system utilizes the flue gas of the suspension calcination reduction kiln (5) as a heat source. The flue gas of the suspension calcination reduction kiln (5) undergoes heat exchange in the preheating system and then enters the flue gas treatment mechanism for treatment and then is discharged. The reducing agent supply mechanism comprises a solid reducing agent supply mechanism and a gas reducing agent supply mechanism, wherein the discharge end of the solid reducing agent supply mechanism is connected to the solid reducing agent feeding port of the suspension calcination reduction kiln (5); and the gas supply port of the gas reducing agent supply mechanism is connected to the gas reducing agent feeding port of the suspension calcination reduction kiln (5).

2. The iron silicate suspension calcination reduction system according to claim 1, characterized in that: It also includes a metering mechanism, which is arranged between the raw material supply mechanism and the preheating system.

3. The iron silicate suspension calcination reduction system according to claim 2, characterized in that: The metering mechanism comprises a metering conveyor belt (14) and a screw feeder (15), wherein the loading end of the metering conveyor belt (14) is connected to the discharge port of the pre-magnetic separator (13), the unloading end of the metering conveyor belt (14) is connected to the feeding port of the screw feeder (15), and the discharge port of the screw feeder (15) is connected to the feeding port of the preheating system.

4. The iron silicate suspension calcination reduction system according to claim 3, characterized in that: The preheating system includes a high-temperature cyclone (22), a low-temperature cyclone (6), a preheating cyclone (4) and a preheating dryer (16); The raw material feed port of the preheating dryer (16) is connected to the discharge port of the screw feeder (15), the discharge port of the preheating dryer (16) is connected to the feed port of the low-temperature cyclone (6), the gas outlet of the low-temperature cyclone (6) is connected to the flue gas treatment mechanism, and the discharge port of the low-temperature cyclone (6) is connected to the feed port of the preheating cyclone (4); The feed port of the high-temperature cyclone (22) is connected to the discharge port of the suspension calcination reduction kiln (5), the gas outlet of the high-temperature cyclone (22) is connected to the feed port of the preheating cyclone (4), the gas outlet of the preheating cyclone (4) is connected to the air inlet of the preheating dryer (16), and the discharge port of the preheating cyclone (4) is connected to the feed port of the suspension calcination reduction kiln (5); The discharge port of the high-temperature cyclone (22) is connected to the feed port of the cooling cyclone (20), and the discharge port of the cooling cyclone (20) is connected to the feed port of the post-magnetic separator (19).

5. The iron silicate suspension calcination reduction system according to claim 4, characterized in that: The gas reducing agent supply mechanism includes an inert gas supply tank (17) and a gas reducing agent supply tank (18), the gas supply ports of the inert gas supply tank (17) and the gas reducing agent supply tank (18) are both connected to the feed port of the cooling cyclone (20), and the gas outlet of the cooling cyclone (20) is connected to the gas reducing agent filling port of the suspension calcination reduction kiln (5).

6. The iron silicate suspension calcination reduction system according to claim 5, characterized in that: It also includes a high-temperature blower (21), which is arranged between the gas outlet of the cooling cyclone (20) and the gas reducing agent filling port of the suspension calcination reduction kiln (5).

7. The iron silicate suspension calcination reduction system according to claim 1, characterized in that: The solid reducing agent supply mechanism comprises a solid reducing agent feeder (2) and a solid reducing agent silo (3), wherein the discharge port of the solid reducing agent silo (3) is connected to the feed port of the solid reducing agent feeder (2), and the discharge port of the solid reducing agent feeder (2) is connected to the solid reducing agent feeding port of the suspension calcination reduction kiln (5).

8. The iron silicate suspension calcination reduction system according to claim 4, characterized in that: The flue gas treatment mechanism comprises a bag dust collector (7), an induced draft fan (8) and a chimney (9); the air inlet of the bag dust collector (7) is connected to the gas outlet of the low-temperature cyclone (6); the exhaust port of the bag dust collector (7) is connected to the input port of the induced draft fan (8); and the output port of the induced draft fan (8) is connected to the air inlet of the chimney (9).

9. A suspension calcination reduction process for iron silicate, using the suspension calcination reduction system according to any one of claims 1 to 8, characterized in that: Including solid material treatment process and flue gas treatment process; The solid material processing process is as follows: the ore and the solid roasting aid are added to the ore mill (11) in proportion through the feeding device (10) for crushing, the crushed material is added to the separator (12) for screening, the material with qualified particle size is screened out and added to the pre-magnetic separator (13) for magnetic separation, the poor iron ore powder is magnetically separated and then metered and transported to the screw feeder (15) by the metering conveyor (14), and the screw feeder (15) is transported to the preheating dryer (16) for preheating and drying by flue gas, and then the dried material and the flue gas are added to the low-temperature cyclone (6) for separation, the separated material is added to the preheating cyclone (4) for further preheating by flue gas, and the separated material is added to the suspension calcination reduction kiln (5) through the feed port to react with the reducing agent by high temperature; After the reaction is completed, the reduction products in the suspension calcination reduction kiln (5) are transported together with the flue gas to a high-temperature cyclone (22) for separation, and the separated reduction products are transported to a cooling cyclone (20) for cooling, and finally magnetically separated and enriched by a post-magnetic separator (19); The flue gas treatment process is as follows: hot air is input into the suspension calcination reduction kiln (5) using a hot air furnace (1), the reduction product in the suspension calcination reduction kiln (5) is transported together with the flue gas to a high-temperature cyclone (22) for separation, the separated flue gas is input into a preheating cyclone (4) to preheat the solid material, the flue gas after heat exchange is input into a preheating dryer (16) to preheat and dry the solid material, and then the flue gas and the dried solid material are input into a low-temperature cyclone (6) for separation, and finally the separated flue gas is discharged through a chimney (9) after being treated to meet the standards.

10. The iron silicate suspension calcination reduction process according to claim 9, characterized in that: The reducing agent in the solid material processing process includes a solid reducing agent and a gas reducing agent. The solid reducing agent is directly added into the suspension calcination reduction kiln (5) through the solid reducing agent feeding port. The gas reducing agent is preheated by heat exchange with the reduction product through the cooling cyclone (20) and then added into the suspension calcination reduction kiln (5) through the gas reducing agent feeding port.

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