A hydrogen flash direct reduction process for metal ore powder

Abstract

The present invention relates to the technical field of metal hydrogen-based smelting, and specifically discloses a hydrogen flash direct reduction process for metal ore powder, which integrates ore powder pretreatment, heating, reduction, separation, cooling, metal smelting, waste heat recovery, and flue gas purification, and realizes functions such as ore powder suspension heating, flash reduction, metal separation, electric furnace smelting, hydrogen preheating, heat recycling, and environmentally friendly emissions. The process flow is highly controllable, the heat energy recycling rate is high, the requirements for raw material quality are low, the processing capacity is large, the mineral processing process and the smelting process can be shortened, and the integrated metal mineral dressing and smelting and the high-efficiency, energy-saving, and environmentally friendly goals of metal hydrogen-based smelting are realized, and significant economic and social benefits are achieved in the field of metal dressing and smelting.

Description

Technical Field

[0001] The present invention relates to the technical field of metal reduction, and in particular to a process for direct hydrogen flash reduction of metal ore powder. Background Art

[0002] Hydrogen-based metallurgy is one of the core technologies for the steel industry's low-carbon transition. By using hydrogen instead of traditional coke as a reducing agent, it significantly reduces CO2 emissions. Traditional blast furnace ironmaking relies on coke (carbon) to reduce iron ore (Fe2O3), producing CO2. Hydrogen-based metallurgy replaces carbon with hydrogen (H2), producing water (H2O), theoretically achieving zero carbon emissions.

[0003] The current technical routes are:

[0004] Direct Reduced Iron (DRI) + Electric Arc Furnace: Hydrogen reduces iron ore to produce sponge iron, which is then made into steel in an electric arc furnace;

[0005] Hydrogen-based blast furnace: hydrogen is mixed into the blast furnace to partially replace coke (transitional solution);

[0006] Hydrogen plasma molten reduction: hydrogen as reducing agent and heat source (Frontier Exploration).

[0007] Current hydrogen metallurgy is developed and improved based on existing technology and equipment. The entire process is long, the DRI time is also long, and there are high requirements for raw materials.

[0008] The hydrogen flash reduction DRI process is a new way to use fine mineral powder DRI. It has the advantages of fast reaction speed and short smelting process. However, there is no mature technology and equipment, and it is still in the experimental and exploratory stage.

[0009] Hydrogen metallurgy technology has moved from the laboratory to demonstration projects, but is still in the early stages of large-scale application.

[0010] Therefore, a hydrogen flash direct reduction process for metal ore powder has become an urgent problem to be solved. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a process for the direct hydrogen flash reduction of metal ore powder. This process, through the steps of ore pretreatment, heating, reduction, separation, heat exchange, smelting, tailings cooling, and flue gas purification, achieves functions such as ore powder suspension heating, flash reduction, metal separation, electric furnace smelting, hydrogen preheating, heat recycling, and environmentally friendly emissions, thereby achieving the goals of high efficiency, energy conservation, and environmental protection in metal hydrogen-based smelting. The metal ore powders processed by this process include, but are not limited to, heavy metal ore powders such as iron ore, copper ore, lead ore, and zinc ore.

[0012] To solve the above technical problems, the present invention provides a technical solution: a hydrogen flash direct reduction process for metal ore powder, comprising the following steps:

[0013] S1. Controllable feeding

[0014] The metal ore powder enters the buffer bin in front of the furnace, and is controlled by a quantitative metering conveyor to enter the screw feeder or vibrating feeder and sent to the Venturi dryer;

[0015] S2, drying, preheating and tailing

[0016] The metal ore powder passes through the Venturi dryer, the first-stage drying cyclone separator, the second-stage drying cyclone separator, the first-stage cyclone preheater, and the second-stage cyclone preheater to remove free water, preheat, and discard non-metallic tailings;

[0017] S3, suspension roasting and heating

[0018] The preheated metal ore powder enters the roaster from the lower side, and is lifted up by the high-temperature gas heated by the burner from the bottom of the roaster and heated to a temperature above the reduction temperature and below the melting point. The heated metal ore powder is then carried upward by the high-temperature airflow out of the roaster and into the high-temperature cyclone separator.

[0019] S4, Flash Direct Restore

[0020] The high-temperature ore powder separated from the high-temperature cyclone separator flows into the reduction furnace from the side through the isolator. The preheated high-temperature hydrogen from the bottom is suspended and moves upward. During this period, the hydrogen directly and fully contacts the high-temperature ore powder to carry out a reduction reaction, and the metal oxides are reduced to form metal particles. This process takes about 2-4 seconds.

[0021] S5. Metal particle heat exchange and separation

[0022] The high-temperature metal particles generated in the reduction furnace fall down in the lower section of the reduction furnace by their own gravity. During the falling process, they exchange heat with the countercurrent hydrogen and are further fully reduced. The heated hydrogen enters the reduction furnace from the lower part of the reduction furnace for flash reduction, and carries the unreduced mineral powder upward out of the reduction furnace.

[0023] S6, electric furnace smelting

[0024] After heat exchange and separation, the metal particles containing residual heat then fall into the electric furnace at the bottom of the reduction furnace, where they are further heated and smelted into molten metal, and other impurities are removed using existing steel smelting technology;

[0025] S7, secondary reduction and separation

[0026] The high-temperature ore powder from the reduction furnace passes through a two-stage cyclone separator for gas-solid separation; hydrogen flows from bottom to top and exchanges heat with the high-temperature ore powder separated by the first-stage reduction separator, which falls by gravity, in the pipeline and undergoes a second direct reduction reaction. The reduced high-temperature metal particles fall by gravity into the electric furnace for further heating and smelting; the unreduced ore powder is carried by the preheated hydrogen into the second-stage reduction separator for gas-solid separation, and the separated hot hydrogen is sent to the lower part of the reduction furnace to participate in the first reduction; the high-temperature gas containing reducing gas separated from the first-stage reduction separator is sent to the top of the burner at the bottom of the roasting furnace, enters the flue for combustion, and then enters the roasting furnace;

[0027] S8, tailings cooling and fresh air preheating

[0028] The high-temperature mineral powder separated by the second-stage reduction separator flows by gravity through the isolator into the multi-stage cyclone cooler configured from top to bottom for countercurrent heat exchange with the cold air, and is cooled to below 80°C and discharged as tailings; the hot air coming out of the first-stage cyclone cooler is introduced into the lower part of the roaster through the flue as combustion air, and is heated by the burner installed there before entering the roaster.

[0029] Furthermore, the high-temperature flue gas separated from the roasting furnace carries the mineral powder separated by the first-stage drying cyclone into the first-stage cyclone preheater, and the high-temperature flue gas separated from the first-stage cyclone preheater enters the second-stage preheating separator for dust removal and then passes through the hydrogen preheater for heat exchange and cooling.

[0030] Furthermore, the medium-temperature flue gas from the hydrogen preheater enters the bottom of the Venturi dryer, bringing the wet mineral powder sent in by the feeder into the first-stage drying cyclone separator. The waste flue gas from the first-stage drying cyclone separator recovers dust through the second-stage drying separator and then enters the waste heat recovery device.

[0031] Furthermore, the flue gas coming out of the waste heat recovery device enters the dust collector and is sent to the desulfurization device through the exhaust fan to remove sulfides in the flue gas, and is discharged after meeting environmental protection standards; the limestone powder slurry in the desulfurization device contacts the sulfuric acid droplets and sulfur dioxide in the sulfur-containing flue gas in a countercurrent manner, reacts to generate calcium sulfite that settles to the bottom, and contacts and reacts with the air introduced from the outside to generate calcium sulfate (gypsum) that is discharged.

[0032] Furthermore, the hydrogen preheater is a tubular heat exchanger, and the hydrogen in the tube of the hydrogen preheater exchanges heat with the high-temperature flue gas outside the tube, and the high-temperature flue gas separated by the second-stage preheating cyclone separator is cooled and used to dry the mineral powder; the waste heat recovery device is also a tubular heat exchanger, and the medium and low-temperature flue gas outside the tube exchanges heat with the water in the tube, and the water is heated and evaporated for waste heat power generation.

[0033] Furthermore, in step S4, a certain amount of mineral powder is always retained in the isolator, which acts as a seal to prevent the hot air of the heating system from contacting the hydrogen in the reduction furnace and causing an explosion; in step S8, a certain amount of mineral powder is always retained in the isolator, which acts as a seal to prevent the reducing gas in the reduction separator from entering the air cyclone cooler and causing an explosion.

[0034] Furthermore, in step S2, the first-stage drying cyclone separator uses the centrifugal force difference caused by the difference in specific gravity of the metal ore powder to separate the metal ore powder from the non-metallic ore powder. The non-metallic ore powder enters the second-stage drying separator, and the separated dust is used as tailings and is drained to the second-stage cyclone cooler for cooling and then discharged to the outside or drained to the dust collector hopper for discharge.

[0035] Furthermore, the metal particles falling from step S5 can also enter the water seal discharge device installed at the bottom of the reduction furnace to be further cooled and sold as metal particle product storage bins, replacing step S6.

[0036] Furthermore, the hydrogen is provided by a methane reforming device as high-temperature hydrogen-containing synthesis gas, or by a coal gasification device as high-temperature hydrogen-containing coal gas, or by other sources of high-purity hydrogen.

[0037] Furthermore, the metal ore powder is roasted, heated, and reduced while in a fluid and suspended state. The metal ore powder is pneumatically conveyed between different locations, with dense-phase heat exchange and dilute-phase flow during the gas-solid mixture transport process. By controlling the airflow velocity at different stages and utilizing the principle of the metal powder's higher specific gravity, the powder is separated from the unreduced ore powder (non-metallic ore powder).

[0038] The advantages of the present invention compared with the existing technology are: the present invention integrates mineral powder pretreatment, heating, reduction, separation, cooling, smelting, waste heat recovery, and flue gas purification into one, the process flow is highly controllable, heat energy is recycled, the requirements for raw material quality are low, the processing capacity is large, the mineral processing process and the smelting process can be shortened, and the integration of metal mineral beneficiation and smelting is realized, which has significant economic and social benefits in the field of metal beneficiation and smelting. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a process flow chart of a hydrogen flash direct reduction process for metal ore powder according to the present invention. The dotted line in the figure is the reducing gas (hydrogen or its synthesis gas), the dashed line is the high-temperature gas flue, and the solid line is the gas-solid mixing flue and pipeline.

[0040] As shown in the figure: 1. Conveyor, 2. Buffer bin, 3. Measuring conveyor, 4. Venturi dryer, 5. Vibrating feeder, 6. High-temperature cyclone separator, 7. Roasting furnace, 8. First-stage cyclone preheater, 9. First-stage drying cyclone separator, 10. Second-stage drying cyclone separator, 11. Reduction furnace, 12. Electric furnace, 13. First-stage reduction separator, 14. Second-stage reduction separator, 15. Waste heat recovery device, 16. Isolator, 17. First-stage cyclone cooler, 18. Second-stage cyclone cooler, 19. Second-stage cyclone preheater, 20. Dust collector, 21. Desulfurization device, 22. Exhaust fan. DETAILED DESCRIPTION

[0041] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "inside", "outside", "vertical", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0042] In the description of the present invention, references to "first feature" and "second feature" may include one or more of these features. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features being described. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of these features.

[0043] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] The following is a detailed description of a hydrogen flash direct reduction process for metal ore powder according to the present invention with reference to the accompanying drawings.

[0045] The working principle of the present invention is as follows: Metal ore powder is suspended and heated by high-temperature gas heated by a burner in the roasting furnace 7 to generate metal oxides, which are then transported. It is then suspended by high-temperature hydrogen in the reduction furnace 11, where the high-temperature metal oxides are flash-reduced to metal particles. The ore powder undergoes gas-solid separation in different cyclone separators, and pneumatic conveying and heat exchange occur in the pipelines between different devices. During the transportation of the gas-solid mixture, dense phase heat exchange and dilute phase flow are used. The airflow velocity at different stages is controlled, and the principle of the higher specific gravity of the reduced metal powder is utilized to achieve separation from the unreduced ore powder. Hydrogen (reducing gas) preheated at different stages within the device is sent to the bottom of the reduction furnace 11, where it moves upward and reacts with the suspended high-temperature ore powder for flash reduction. Fresh air entering from the outside recovers heat in the cooling section and is sent to the lower part of the roasting furnace 7 to heat the suspended roasted ore powder. The exhaust fan 22 provides power for pneumatic conveying and gas-solid separation of the entire device, and provides combustion air for the combustion station. The high-temperature flue gas discharged from the roasting furnace 7 provides heat energy for hydrogen preheating and mineral powder drying preheating. Fresh air exchanges heat with the unreduced high-temperature non-metallic mineral powder (tailings), and the heat of the tailings is recovered and used as combustion-supporting gas.

[0046] Combined with attachment Figure 1 The specific implementation process of the hydrogen flash direct reduction process of metal ore powder of the present invention is as follows:

[0047] A hydrogen flash direct reduction process for metal ore powder comprises the following steps:

[0048] S1. Controllable Feeding. Metal ore powder enters the pre-furnace surge bin 2 via conveyor 1, then is controlled by a quantitative metering conveyor 3 to enter a screw feeder or vibrating feeder 5, which feeds the Venturi dryer 4. Conveyor 1 and vibrating feeder 5 feature remote and local control, monitoring, alarm, and interlocking capabilities. The metering conveyor 3 is equipped with an on-site PLC system and a DCS, enabling remote and local monitoring, alarm, and interlocking capabilities. The surge bin 2 is equipped with a material level detector, providing remote and local monitoring, high and low alarms, and interlocking capabilities. The Venturi dryer 4 is equipped with inlet and outlet temperature and pressure differential detection instruments, providing remote and local monitoring and alarm capabilities.

[0049] S2. Drying, preheating, and tailings disposal. The ore powder passes through the Venturi dryer 4, the first-stage drying cyclone separator 9, and the first-stage cyclone preheater 8 to remove free water and preheat the powder. The first-stage drying cyclone separator 9 utilizes the centrifugal force difference caused by the difference in specific gravity of the ore powder to separate metallic ore powder from non-metallic ore powder. The non-metallic ore powder enters the second-stage drying cyclone separator 10 for separation. The separated dust, as tailings, is directed to the ash hopper of the dust collector 20 or the second-stage cyclone cooler 18 for cooling and discharge. The gas separated by the first-stage cyclone preheater 8 enters the second-stage cyclone preheater 19 for further separation of the ore powder before discharge. The top inlet of the first-stage cyclone preheater 8, the first-stage drying cyclone separator 9, the second-stage drying cyclone separator 10, the second-stage cyclone cooler 18, and the second-stage cyclone preheater 19 is equipped with temperature and pressure measuring instruments, and the cone outlet is equipped with a temperature measuring instrument to enable remote monitoring and alarm functions. The dust collector 20 is equipped with a PLC and a DCS system, enabling remote and local monitoring, alarms, and interlocking functions. The flue gas outlet of the second-stage cyclone preheater 19 is equipped with an oxygen detector to monitor the oxygen content of the roasting flue gas in real time, controlling the gas flow through a circuit to ensure safe combustion. The flue gas outlet duct of the second-stage drying cyclone separator 10 is equipped with combustible gas detectors such as hydrogen, methane, and carbon monoxide, enabling remote and local monitoring, alarms, and interlocking to prevent explosions and deflagrations.

[0050] S3. Suspended roasting and heating. The preheated metal ore powder from the first-stage cyclone preheater 8 flows into the roaster 7 from the lower side, utilizing the height difference. High-temperature gases entering from the bottom of the roaster 7, heated by the burner, are lifted and suspended, heating the powder to a temperature above the reduction temperature but below the melting point, generating metal oxides. After heating, the metal ore powder containing the metal oxides is carried upward by the high-temperature airflow out of the roaster 7 and into the high-temperature cyclone separator 6. Redundant temperature and pressure sensors are installed at the top and bottom entrances of the roaster 7 to enable remote and local monitoring, alarms, and interlocking functions.

[0051] S4, Flash Direct Reduction. The high-temperature mineral powder separated from the high-temperature cyclone separator 6 flows by gravity from the side through the isolator 16 into the reduction furnace 11. Preheated, high-temperature hydrogen gas suspends and flows upward from the bottom. During this period, the hydrogen directly and fully contacts the high-temperature mineral powder, undergoing a reduction reaction, reducing the metal oxides to form metal particles. This process takes approximately 2-4 seconds. A certain level of mineral powder is always retained within the isolator 16, ensuring that the pressure differential between the inlet and outlet cannot be breached. This acts as an isolation seal, preventing the hot flue gas from the heating system from contacting the hydrogen in the reduction furnace and causing an explosion. The mineral powder that has not undergone the reduction reaction is carried upward by excess hydrogen and reduction exhaust gas into the first-stage reduction separator 13. Temperature and pressure monitoring instruments are installed at the inlet and outlet of the reduction furnace 11 and isolator 16.

[0052] S5. Metal Particle Heat Exchange and Separation. The high-temperature metal particles generated in the reduction furnace 11 fall by gravity in the lower section of the reduction furnace 11. During their descent, they exchange heat with the upstream hydrogen gas and undergo further reduction. Flow rate, oxygen, and hydrogen detection instruments are installed in the upper and lower sections of the reduction furnace 11, enabling remote and on-site monitoring and interlocking functions, and monitoring the temperature, speed, concentration, excess coefficient, and safety of the flash reduction process.

[0053] S6. Electric furnace smelting. After heat exchange and separation, the metal particles, which contain a large amount of residual heat, then fall into the electric furnace 12 at the bottom of the reduction furnace, where they are further heated and smelted into molten metal. Other impurities are removed using existing steel smelting technology. Electric furnace 12 is a mature smelting equipment equipped with temperature, level, current, voltage, and exhaust gas detection instruments, enabling remote and on-site monitoring.

[0054] S7. Secondary reduction and separation. The high-temperature ore powder from the reduction furnace 11 passes through a two-stage cyclone separator for gas-solid separation. Hydrogen gas exchanges heat with the high-temperature ore powder separated by the first-stage reduction separator 13 and falls by gravity in the pipeline, undergoing a second direct reduction reaction. The reduced high-temperature metal particles fall by gravity into the electric furnace 12 for further heating and smelting. The unreacted ore powder (non-metallic tailings powder) is carried by the preheated hydrogen into the second-stage reduction separator 14 for gas-solid separation. The separated hot hydrogen gas is sent to the lower part of the reduction furnace 11 to participate in the first reduction. The high-temperature gas containing reducing gas separated from the first-stage reduction separator 13 is sent to the top of the burner at the bottom of the roasting furnace 7, enters the flue for combustion, and then enters the roasting furnace 7. Temperature, pressure, oxygen, and hydrogen detection instruments are installed at the entrances of the first-stage reduction separator 13 and the second-stage reduction separator 14 to realize remote and on-site monitoring functions.

[0055] S8. Tailings cooling and new air preheating. The high-temperature tailings powder separated by the second-stage reduction separator 14 flows through the isolator 16 by gravity using the position difference to enter the multi-stage cyclone cooler configured from top to bottom for countercurrent heat exchange with the cold air, and is cooled to below 80°C as the tailings discharge system. The preheated air coming out of the first-stage cyclone cooler 17 is introduced into the lower part of the roasting furnace 7 through the flue as combustion air, and is heated by the burner installed there before entering the roasting furnace 7; a certain height of mineral powder is always retained in the isolator 16, and the pressure difference between the inlet and outlet cannot be broken, so as to prevent the reducing gas in the reduction separator from entering the air cyclone cooler and causing an explosion. The inlet and outlet of the multi-stage cyclone cooler are equipped with temperature and pressure detection instruments to realize remote and on-site monitoring functions.

[0056] S9, tailings treatment. If the metal content in the tailings still has recovery value, it can be sorted again, and the selected concentrate will enter the pre-furnace buffer bin 2 again;

[0057] S9, hydrogen preheating. The high-temperature flue gas separated from the high-temperature separator 6 carries the mineral powder from the first-stage drying separator 9 into the first-stage cyclone preheater 8. The high-temperature flue gas separated from the first-stage cyclone preheater 8 enters the second-stage preheating separator 19 for dust removal and then passes through the hydrogen preheater for heat exchange and cooling. The hydrogen preheater is a tubular heat exchanger. The hydrogen in the tube of the hydrogen preheater exchanges heat with the high-temperature flue gas outside the tube. The high-temperature flue gas separated by the second-stage preheating cyclone separator is cooled to medium-temperature flue gas for drying the mineral powder. The hydrogen preheater is equipped with temperature and pressure detectors at the flue gas inlet and outlet, and a hydrogen detector at the flue gas outlet, to achieve remote and on-site monitoring and interlocking functions.

[0058] S10, flue gas waste heat recovery. The medium-temperature flue gas coming out of the hydrogen preheater enters the bottom of the venturi dryer 4, and brings the wet mineral powder sent in by the feeder into the first-stage drying cyclone separator 9. The waste flue gas coming out of the first-stage drying cyclone separator 9 passes through the second-stage drying separator to recover dust and then enters the waste heat recovery device 15. The waste heat recovery device 15 is a tubular heat exchanger, and the medium- and low-temperature flue gas outside the tube exchanges heat with the water inside the tube, heating and evaporating the water for waste heat power generation. The waste heat recovery device 15 is equipped with temperature and pressure detectors at the flue gas inlet and outlet, a hydrogen detector at the flue gas outlet, and temperature and pressure detectors at the water inlet and outlet, to realize remote and on-site monitoring and interlocking functions.

[0059] S11. Flue gas purification. The flue gas from the waste heat recovery device 15 enters the dust collector 20 and is sent to the desulfurization device 21 via the main exhaust fan 22 to remove sulfides from the flue gas. The flue gas is discharged after meeting environmental protection standards. The limestone slurry in the desulfurization device 21 contacts the sulfuric acid droplets and sulfur dioxide in the sulfur-containing flue gas in a countercurrent manner, reacting to produce calcium sulfite that settles to the bottom. It then reacts with the air introduced from the outside to produce calcium sulfate (gypsum) that is discharged. The dust collector 20 and exhaust fan 22 are configured as a complete set of equipment with an on-site PLC system and DCS monitoring. The flue gas inlet and outlet of the desulfurization device 21 are equipped with temperature, sulfide, and dust detection instruments to achieve remote and on-site monitoring and interlocking functions.

[0060] S12, collecting dust and discharging it to the outside. The dust collected by the dust collector 20 is discharged to the outside as tailings.

[0061] In one embodiment of the present application, the metal particles falling from step S5 can also enter a water seal device installed at the bottom of the reduction furnace for further cooling and be sold as metal particle product storage bins, replacing step S6.

[0062] Preferably, the roasting furnace 7 is equipped with a main combustion station for providing heat for heating the mineral powder, using natural gas or coal gas as fuel. The temperature for heating the mineral powder is determined according to different metal mineral powders. The principle is that the roasting temperature is lower than the melting point of the metal mineral powder and higher than the reduction temperature of the metal mineral powder and hydrogen.

[0063] Preferably, the hydrogen is provided by a methane reforming device as a high-temperature synthesis gas containing hydrogen, or by a coal gasification device as a high-temperature coal gas containing hydrogen, or high-purity hydrogen is used.

[0064] In the present invention, the drying cyclone separator, cyclone preheater, cyclone cooler, high-temperature cyclone separator, etc. mentioned are non-standard cyclones designed according to the processing capacity of the device, the properties of the mineral powder and the flow rate, and are used in different process parts to achieve the function of gas-solid separation.

[0065] In one embodiment of the present application, the metal ore powder is roasted, heated and reduced in a flowing and suspended state; the metal ore powder is pneumatically transported between different parts, and during the transportation of the gas-solid mixture, dense phase heat exchange and dilute phase flow are carried out, and the air flow velocity at different stages is controlled. The principle of the higher specific gravity of metal and ore powder is utilized to achieve separation from non-metallic ore powder.

[0066] In the present invention, the fineness of the metal ore powder is determined based on a ore powder particle reduction experiment.

[0067] During the entire process of the present invention, the temperature, pressure, flow rate, flow rate, level and composition of solid mineral powder, gas and gas-solid mixture are detected throughout the entire process, and a DCS system is used for process control and monitoring. The necessary safety interlocks and equipment protection chains are set to ensure the safe operation of the system.

[0068] The present invention integrates low-carbon metallurgy technology, direct reduction smelting technology, hydrogen direct reduction smelting technology, powdered mineral hydrogen flash reduction smelting, and metal mineral dressing and smelting.

[0069] The present invention realizes that the roasting and reduction of metal ore powder occur in different containers. The powdered mineral is heated to above the reduction temperature by the roasting furnace 7, and flows into the lower reduction furnace 11 by gravity due to the height difference of the position, and is suspended by the high-temperature hydrogen to undergo a flash reduction reaction.

[0070] The present invention utilizes the principle that the specific gravity of the reduced metal powder is greater than that of its oxide, and uses appropriate wind speed to separate the metal powder during the material transportation process.

[0071] The present invention achieves multiple reductions of metal ore powder, maximizing metal recovery from the ore powder. Reducing hydrogen undergoes an initial reduction with the high-temperature ore powder in a reduction furnace 11. The resulting metal powder then falls through a pipe in the lower portion of the reduction furnace, exchanging heat in the opposite direction with the preheated hydrogen. This allows further reaction of unreacted iron powder particles. The resulting metal powder is then sent to an electric furnace 12 for smelting before being sent to the next process.

[0072] The partially reduced ore fines separated from the reduction furnace 11 undergo a further reduction reaction with hydrogen in the cooling section, ensuring maximum reduction and recovery of the metal oxides in the ore fines while also recovering heat. The high-temperature flue gas containing the reducing gas separated after reduction is then fed to the bottom inlet of the roasting furnace 7 for combustion, where it then enters the roasting furnace 7 to suspend and roast the ore fines.

[0073] The reducing hydrogen required by the present invention can be provided by a methane reforming device to provide high-temperature hydrogen-containing synthesis gas, or by a coal gasification device to provide high-temperature hydrogen-containing coal gas, making full use of the heat in the high-temperature synthesis gas, and also using high-purity hydrogen.

[0074] The cooling section of the present invention is divided into two sections. In one section, fresh air drawn into the device undergoes countercurrent heat exchange with the reduced ore powder through multi-stage cyclone cooling. The heated hot air is then fed to the roaster for combustion and suspension. The cooled ore powder (less than 80°C) is then fed to a magnetic separator for recovery as reduced magnetic ore. In the other section, reducing gas introduced from an external source undergoes countercurrent, cyclone cooling with the reduced ore powder. This stage allows for a second reduction reaction and metal powder separation. The heated reducing gas is then fed to the reduction furnace, while the cooled metal powder is fed to an electric furnace 12 for smelting before being sent to the next process.

[0075] The mineral powder processed by the present invention is realized in a flowing and suspended state. The mineral powder is pneumatically conveyed between different parts of the device. During the transportation of the gas-solid mixture, dense phase heat exchange and dilute phase flow are carried out. The air flow velocity at different stages is controlled, and the principle of the higher specific gravity of the reduced metal powder is utilized to achieve separation from the unreduced mineral powder.

[0076] The present invention realizes the integration of mineral processing and smelting, can process the medium and low grade ore powder in the mineral processing stage to generate metal products, shortens the mineral processing process, and the tailings output from the roasting furnace 7 have activity due to high temperature roasting and can be used as building material raw materials, greatly reducing the cost of tailings management.

[0077] This process estimates the cost of fuel and reducing gas by referring to the reducing gas and fuel consumption of the iron ore magnetization roasting device. The relevant calculations are as follows:

[0078] 1. A magnetized roasting device using coal gasification as fuel and reducing gas reduces ferric oxide (Fe2O3) to ferroferric oxide (Fe3O4). Each ton of ore powder (45% iron content) processed consumes 104 kg of coal (5500 kcal). Theoretically, this invention requires 104 × 3 = 312 kg of coal to reduce iron oxide to metallic iron. Considering the excess atmosphere for complete reduction, the actual coal consumption required to process one ton of ore powder is calculated at 67% excess, resulting in a fuel and reducing gas cost of approximately RMB 500 per ton (of ore powder).

[0079] 2. Taking natural gas steam reforming to produce hydrogen as an example, ferric oxide (Fe2O3) is reduced to ferroferric oxide (Fe3O4). Theoretically, the natural gas consumption (7000 kcal) is about 40 cubic meters for each ton of ore fines (iron content 45%) processed. Theoretically, the device needs to consume 40×3=120 cubic meters of natural gas to reduce the iron oxide to metallic iron. Considering the excess atmosphere for complete reduction, the actual natural gas consumption required to process one ton of ore fines is calculated as 67% excess, which is about 200 cubic meters of natural gas. The unit price of natural gas is 3 yuan, so the cost of fuel and reducing gas is about 200×3=600 yuan / ton (ore fines);

[0080] It can be seen that this process can save production costs and has significant economic and social benefits in the field of metal smelting.

[0081] The above description of the present invention and its embodiments is non-limiting. The accompanying drawings illustrate only one embodiment of the present invention. Due to the significant differences in the physical and chemical properties of different metal ore powders, the actual structure is not limited thereto. All stages of the process device need to be targeted for addition, reduction, and optimization. In short, if a person skilled in the art is inspired by this, and does not deviate from the purpose of the invention, without creatively designing a structure and embodiment similar to this technical solution, they shall fall within the scope of protection of the present invention.

Claims

1. A process for direct reduction of metal ore powder by hydrogen flash, characterized in that: The following steps are involved: S1. Controllable feeding The metal ore powder enters the buffer bin in front of the furnace, and is controlled by a quantitative metering conveyor to enter the screw feeder or vibrating feeder and sent to the Venturi dryer; S2, drying, preheating and tailing The metal ore powder passes through the Venturi dryer, the first-stage drying cyclone separator, the second-stage drying cyclone separator, the first-stage cyclone preheater, and the second-stage cyclone preheater to remove free water, preheat, and discard non-metallic tailings; S3, suspension roasting and heating The preheated metal ore powder enters the roaster from the lower side, and is lifted up by the high-temperature gas heated by the burner from the bottom of the roaster and heated to a temperature above the reduction temperature and below the melting point. The heated metal ore powder is then carried upward by the high-temperature airflow out of the roaster and into the high-temperature cyclone separator. S4, Flash Direct Restore The high-temperature ore powder separated from the high-temperature cyclone separator flows into the reduction furnace from the side through the isolator. The preheated high-temperature hydrogen from the bottom is suspended and moves upward. During this period, the hydrogen directly and fully contacts the high-temperature ore powder to carry out a reduction reaction and generate metal particles. This process takes about 2-4 seconds. S5. Metal particle heat exchange and separation The high-temperature metal particles generated in the reduction furnace fall down in the lower section of the reduction furnace by their own gravity. During the falling process, they exchange heat with the countercurrent hydrogen and are further fully reduced. The heated hydrogen enters the reduction furnace from the lower part of the reduction furnace for flash reduction, and carries the unreduced mineral powder upward out of the reduction furnace. S6, electric furnace smelting After heat exchange and separation, the metal particles with residual heat then fall into the electric furnace at the bottom of the reduction furnace, where they are further heated and melted into molten metal and other impurities are removed; S7, secondary reduction and separation The high-temperature ore powder from the reduction furnace passes through a two-stage cyclone separator for gas-solid separation; hydrogen flows from bottom to top and exchanges heat with the high-temperature ore powder separated by the first-stage reduction separator, which falls by gravity, in the pipeline and undergoes a second direct reduction reaction. The reduced high-temperature metal particles fall by gravity into the electric furnace for further heating and smelting; the unreacted ore powder is carried by the preheated hydrogen into the second-stage reduction separator for gas-solid separation, and the separated hot hydrogen is sent to the lower part of the reduction furnace to participate in the first reduction; the high-temperature gas containing reducing gas separated from the first-stage reduction separator is sent to the top of the burner at the bottom of the roasting furnace, enters the flue for combustion, and then enters the roasting furnace; S8, tailings cooling and fresh air preheating The high-temperature mineral powder separated by the second-stage reduction separator flows by gravity through the isolator into the multi-stage cyclone cooler configured from top to bottom for countercurrent heat exchange with the cold air, and is cooled to below 80°C and discharged as tailings; the hot air coming out of the first-stage cyclone cooler is introduced into the lower part of the roaster through the flue as combustion air, and is heated by the burner installed there before entering the roaster.

2. The hydrogen flash direct reduction process for metal ore powder according to claim 1, characterized in that: The high-temperature flue gas separated from the roasting furnace carries the mineral powder from the first-stage drying cyclone into the first-stage cyclone preheater. The high-temperature flue gas separated from the first-stage cyclone preheater enters the second-stage preheating separator for dust removal and then passes through the hydrogen preheater for heat exchange and cooling.

3. The hydrogen flash direct reduction process for metal ore powder according to claim 2, characterized in that: The medium-temperature flue gas from the hydrogen preheater enters the bottom of the Venturi dryer, and brings the wet mineral powder sent by the feeder into the first-stage drying cyclone separator. The waste flue gas from the first-stage drying cyclone separator recovers dust after passing through the second-stage drying separator and enters the waste heat recovery device.

4. The hydrogen flash direct reduction process for metal ore powder according to claim 3, characterized in that: The flue gas coming out of the waste heat recovery device enters the dust collector and is sent to the desulfurization device through the exhaust fan to remove sulfides in the flue gas, and is discharged after meeting environmental protection standards.

5. The hydrogen flash direct reduction process for metal ore powder according to claim 4, characterized in that: The hydrogen preheater is a tubular heat exchanger, and the hydrogen in the tube of the hydrogen preheater exchanges heat with the high-temperature flue gas outside the tube, reducing the high-temperature flue gas separated by the second-stage preheating cyclone separator to be used for drying the mineral powder; the waste heat recovery device is also a tubular heat exchanger, and the medium and low-temperature flue gas outside the tube exchanges heat with the water in the tube, heating and evaporating the water for waste heat power generation; the flue gas after waste heat recovery passes through the desulfurization device to remove sulfides in the flue gas, and then is discharged; the limestone powder slurry in the desulfurization device contacts countercurrently with the sulfuric acid droplets in the sulfur-containing flue gas, reacts, and generates calcium sulfite, which settles to the bottom, contacts and reacts with the air introduced from the outside, and generates calcium sulfate, which is discharged.

6. The hydrogen flash direct reduction process for metal ore powder according to claim 5, characterized in that: In step S4, a certain height of mineral powder is always retained in the isolator. The height of the mineral powder is based on the principle that the gas pressure difference between the inlet and outlet ends cannot be exceeded, which plays a sealing role and prevents the oxygen-containing hot flue gas of the heating system from contacting with the hydrogen in the reduction furnace and causing explosion; In step S8, a certain height of mineral powder is always retained in the isolator. The height of the mineral powder is based on the principle that the gas pressure difference at the inlet and outlet ends cannot be broken, which plays a sealing role and prevents the reducing gas in the reduction separator from entering the air cyclone cooler and causing an explosion.

7. The hydrogen flash direct reduction process for metal ore powder according to claim 6, characterized in that: In step S2, the first-stage drying cyclone separator uses the centrifugal force difference caused by the difference in specific gravity of the metal ore powder to separate the metal from the non-metal in the metal ore powder. The non-metallic ore powder enters the second-stage drying separator. The dust separated by the second-stage drying cyclone separator is used as tailings and is drained to the second-stage cyclone cooler for cooling and then discharged, or drained to the dust collector hopper and then discharged.

8. The hydrogen flash direct reduction process for metal ore powder according to claim 7, characterized in that: The metal particles falling from step S5 can also enter the water seal discharge device at the bottom of the reduction furnace for further cooling and be sold as metal particle product storage bins, replacing step S6.

9. The hydrogen flash direct reduction process for metal ore powder according to claim 8, characterized in that: The hydrogen is provided by a methane reforming device as high-temperature synthesis gas containing hydrogen, or by a coal gasification device as high-temperature coal gas containing hydrogen and carbon monoxide, or high-purity hydrogen is used.

10. The hydrogen flash direct reduction process for metal ore powder according to claim 9, characterized in that: The metal ore powder is moved and reduced in a flowing and suspended state; the metal ore powder is pneumatically transported between different parts, and during the transportation of the gas-solid mixture, dense phase heat exchange and dilute phase flow are carried out. The air flow speed at different stages is controlled, and the principle of the higher specific gravity of the reduced metal powder is utilized to achieve separation from the unreduced ore powder.

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