Low-carbon and energy-saving ore reduction method and device

Abstract

The invention discloses a low-carbon and energy-saving ore reduction method and device. Comprising the following steps: removing adsorbed water of a raw material by using waste heat of furnace gas, removing residual crystal water in the raw material by using the furnace gas generated by self reaction, performing pre-reduction, melt separation and deep reduction on metal oxide, preparing mixed high-temperature gas, continuously injecting the prepared liquid alloy into a high-frequency molten iron condenser at a constant flow rate, casting and the like. The physical sensible heat and chemical heat of the high-temperature reducing gas are fully utilized to heat the raw materials, and the high-temperature reducing gas is efficiently utilized; elements such as iron and nickel in the raw materials are subjected to solid-state reduction by fully utilizing carbon monoxide and hydrogen generated by chemical reaction in the lower hearth furnace, so that energy conservation, carbon reduction and emission reduction are realized; the temperature of the melting reaction zone is uniform, and under strong electromagnetic stirring, the heat transfer speed is high, the temperature gradient in the furnace is low, and the temperature equalization time is short; and the power consumption per unit product and the comprehensive energy consumption are respectively reduced by more than 20% and 26% compared with the national first-grade energy consumption limit.

Description

Technical Field

[0001] This invention relates to the field of ferrous alloy smelting technology, and in particular to the production of ferrous reduction furnaces, specifically to a low-carbon and energy-saving ore reduction method and apparatus. Background Technology

[0002] Currently, traditional hot furnace smelting has some technical defects that cannot meet the needs of actual production, specifically:

[0003] 1. The process is long, with many control points, a high failure rate, a large power installed capacity, high overall energy consumption, and a low yield of molten iron (about 90%). The raw materials heated in the hot charging process experience a temperature drop of 40-60% in open ladles and open silos, resulting in significant heat loss.

[0004] The cold-loading process includes: batching station (10-15 sets of raw material tanks), upper vibrator (10-15 units), electronic scale (10-15 units), lower vibrator (10-15 units), batching belt conveyor (1 line), feeding inclined bridge or belt conveyor (1 set), furnace top material distribution belt conveyor (1 set), ring material distributor (1 set), furnace top silo (10-15 units), slender material pipes (15-17, 15-25 meters long), closed submerged arc furnace, pit casting, natural cooling of products, loader transfer of products, pit cleaning and restoration, manual finishing, crushing, and packaging.

[0005] The hot charging process includes: batching station (10-15 sets of raw material tanks), upper vibrator (10-15 units), electronic scale (10-15 units), lower vibrator (10-15 units), batching belt conveyor (1 line), feeding inclined bridge or belt conveyor (1 set), rotary heating kiln, open hot material bag, large overhead crane, vertical lifting of 30-40 meters, horizontal movement of tens of meters, open furnace top silo (10-15 units), slender material pipes (15-17, 15-25 meters long), closed submerged arc furnace, pit casting, natural cooling of products, loader transfer of products, pit cleaning and restoration, manual finishing, crushing, and packaging.

[0006] 2. The three-story area above the furnace cover of the submerged arc furnace is completely occupied by equipment such as electrodes, electrode holding systems, lifting systems, short mesh systems, cooling systems, and paste-adding platforms. There is no room to install heating furnaces or equipment for treating and utilizing furnace gas (for closed furnaces, the furnace gas is a reducing gas mainly composed of CO, commonly known as raw coal gas; for semi-closed furnaces, the furnace gas is high-temperature, dusty flue gas mainly composed of air; the following explanation focuses on the furnace gas from closed furnaces). The recovery and utilization of furnace gas requires off-site treatment and utilization, resulting in a significant loss of sensible heat.

[0007] 3. The furnace depth is relatively shallow, and the CO produced in the furnace reaction cannot be reduced to solid state with the furnace charge before overflowing to the surface, thus increasing the amount of coke used. High particle size requirements are placed on the raw materials; otherwise, poor permeability will severely deteriorate the furnace conditions.

[0008] 4. The sealing between the electrode through-holes and the electrodes in a closed submerged arc furnace requires a large amount of nitrogen. Nitrogen generation equipment involves high investment and consumes significant power. The large fluctuations in furnace gas production in a closed submerged arc furnace present complex technical challenges for sealing control. Because changes in nitrogen pressure cannot be synchronized with changes in furnace gas pressure, when the furnace gas pressure decreases, nitrogen enters the furnace, reducing the purity of the furnace gas. Conversely, when the pressure increases, furnace gas overflows, potentially causing safety accidents.

[0009] 5. With furnace temperatures reaching 800-1000℃, conductive copper tiles, pressure rings, and other equipment installed inside the furnace are highly susceptible to damage, leading to a decrease in the operating rate of the submerged arc furnace. Water-cooled equipment such as copper tiles and pressure rings often leaks into the furnace, which can worsen furnace conditions or even cause safety accidents in severe cases.

[0010] 6. Large amounts of cooling water are required, resulting in high operating costs for water treatment and water supply and drainage. Water quenching of slag consumes a lot of water, causes serious environmental pollution, and wastes the sensible heat of the slag.

[0011] 7. Layered pit casting and manual crushing result in more slag inclusions in the product, leading to a loss of 200-400 yuan / ton from casting to packaging.

[0012] Due to the aforementioned defects, the comprehensive energy consumption per unit product is far higher than the national energy consumption limit level 1. For example, the comprehensive energy consumption of FeMn68Si18 typically reaches 980-1000 kgce / t, which is 13.95-16.3% higher than the 860 kgce / t of the level 1 standard in GB 31341-2017; the electricity consumption per unit product is basically around 4000 kWh / t, which is 5.3% higher than the 3800 kWh / t of the level 1 standard in GB 31341-2017; and the coke consumption is 500-520 kg / t. Summary of the Invention

[0013] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: a low-carbon and energy-saving ore reduction method, comprising the following steps:

[0014] (1) Using the waste heat of the furnace gas to remove the adsorbed water from the raw materials: The raw materials prepared by the batching station are put into the dehydration chamber at the top of the vertical series double-chamber DC furnace; the bottom of the dehydration chamber is connected to the upper section of the DC furnace with a large open size. The mixed raw materials in the chamber are baked by the waste heat of the medium temperature furnace gas in the upper section of the DC furnace. The temperature gradually rises from the room temperature to 120℃-250℃. The adsorbed water in the raw materials is converted into steam. The generated water vapor slowly overflows from the surface of the dehydration chamber, thereby avoiding the water vapor from entering the furnace gas and reducing the calorific value of the furnace gas.

[0015] (2) Use the furnace gas generated by its own reaction to remove the residual water of crystallization in the raw materials and to pre-reduce the metal oxides: blow the high-temperature mixed gas prepared in step (4) into the upper section of the DC furnace; the combustible furnace gas in the furnace gas comes into contact with the high-temperature mixed gas and burns, releasing a large amount of heat; at the same time, the water vapor in the high-temperature mixed gas reacts with the hot coke to obtain CO and H2, and CO and H2 react with O2 to release heat; the heat obtained from the above reactions together raises the furnace temperature to the required temperature, so that the raw materials in the furnace chamber of the upper section of the DC furnace are heated to above 800°C;

[0016] The gases produced by the reaction of the high-temperature mixed gas with coke and the unreacted furnace gas from the lower section of the once-through furnace both move upwards, while the furnace charge moves downwards. During the upward process, these gases continuously exchange heat with the slowly descending furnace charge. When the furnace gas overflows from the surface of the furnace charge in the upper section of the once-through furnace, the furnace gas temperature has dropped to 150-250℃. The furnace gas overflowing from the furnace charge surface enters the furnace gas purification system under the suction force of the induced draft fan of the purification system. Since the sensible heat of the furnace gas at a temperature of about 1000℃ in the lower section of the once-through furnace and the sensible heat of the high-temperature mixed gas produced by the slag sensible heat recovery device are recovered and utilized, and part of the chemical energy of the furnace gas is used to heat the furnace charge to above 800℃, and to produce pre-reduced furnace charge in a low-valence state or metallic state, this step can achieve a power saving of 20-25%.

[0017] (3) Melting and Deep Reduction: The high-temperature pre-reducing raw material after reaction in the upper section of the DC furnace continuously enters the lower section of the DC furnace through the high-temperature pre-reducing raw material descending channel in the middle section of the DC furnace; DC power is applied to the lower section of the DC furnace, and under the action of the high-power power supply, the temperature of the pre-reducing raw material in the lower section of the DC furnace rises rapidly to the melting point and melts rapidly under the action of DC arc; after melting, the metal phase and slag phase in the pre-reducing raw material separate, and the slag phase in the pre-reducing raw material mixes with the flux to form a new low-melting-point slag phase; the unreduced metal oxides in the low-melting-point slag phase undergo a liquid-solid reaction with coke, and after the reaction, a liquid alloy and discarded slag phase with the composition conforming to the product standard are obtained; the slag phase participating in the above reaction, namely the liquid mineral phase and the solid coke, form a violent convection motion under the strong impact of a high-speed unidirectional electron beam of tens of thousands of amperes, and at the same time, the slag phase impacts the coke phase at high speed, the kinetic conditions are very superior, and the reaction rate is greatly accelerated; the reaction yields a liquid alloy, liquid slag and high-temperature furnace gas with CO as the main component that meet the design requirements;

[0018] (4) Preparation of mixed high-temperature gas: The liquid slag obtained in step (3) is transported to the insulated container of the slag sensible heat recovery device; high-pressure air and high-pressure water mist are introduced into the heat exchanger chamber of the recovery device. The high-pressure air and high-pressure water mist undergo intense heat exchange with the slag in the heat exchanger chamber of the recovery device, resulting in the water mist being vaporized into high-temperature water vapor, and the high-pressure air being heated into high-temperature gas. The slag is transformed into low-temperature granular products; the high-temperature mixed gas is directly transported to the upper section of the DC furnace for use; in the insulated container, the small amount of metal phase in the liquid slag will be completely separated from the liquid slag phase. After separation, the metal phase precipitates at the bottom of the insulated container and is discharged from the liquid alloy outlet pipe at the bottom of the device after a period of time. After solidification and cooling, qualified products are obtained.

[0019] (5) The liquid alloy obtained in step (3) is continuously injected into a high-frequency molten iron condenser at a constant flow rate; the high-frequency molten iron condenser has dozens to hundreds of fast-solidifying precision rod molds, and the precision rod molds are circulated with a high-speed cooling medium, which can make the liquid solidify quickly; the inner cavity of the precision rod mold is a frustum shape with a smaller upper part and a larger lower part; after one precision rod mold is filled with molten iron, it is automatically rotated out of the casting station under the action of the drive mechanism, and the next precision rod mold is simultaneously rotated into the casting station; before rotating into the casting station, a certain amount of alloy powder is added to the bottom of the inner cavity of the rod mold through an external powder adding device; this cycle continues until all casting is completed; when the solidified round rod is rotated to the demolding station, it will automatically fall off and cool. The product required by the user is then obtained. The high-frequency molten iron condenser has a high-frequency vibration function, maintaining vibration throughout the casting process. Its functions are: 1) to accelerate the solidification of high-temperature molten iron, refine grains, and improve product quality; 2) to maintain relative movement between the precision mold and the injected molten iron, preventing the high-temperature liquid metal from adhering to the mold wall and keeping the casting rod slightly separated from the mold; and 3) to allow the solidified casting rod to detach from the mold at the demolding station. The vibration frequency of this high-frequency molten iron condenser is 50-10000Hz. The drive mechanism drives the frame to rotate intermittently. The frame, through spring steel plates, drives the platform to rotate periodically in a "stop-rotate-stop" cycle, with an indexing period of 0.5-5 seconds. The inner diameter of the inner mold of the rod-making mold... The height of the rod-making mold is 300-1500mm.

[0020] The vertically connected double-chamber DC furnace includes a dehydration chamber, an upper section of the DC furnace, a middle section of the DC furnace, and a lower section of the DC furnace arranged from top to bottom.

[0021] The dehydration chamber is directly fixed to the top plate of the upper section of the DC furnace, without a cover plate or bottom plate. A material level detector is installed on its top, and a furnace gas detector is installed inside the chamber.

[0022] The upper section of the DC furnace has a furnace gas outlet at its top, and a No. 2 furnace gas temperature and flow meter is installed at the furnace gas outlet. From bottom to top, an annular furnace gas box and an annular mixing gas box are arranged on the outer bottom of the upper section of the DC furnace. The furnace chamber of the upper section of the DC furnace is a bottomless furnace chamber. A refractory material layer is provided on the inner wall of the furnace shell of the upper section of the DC furnace, and permeable walls are provided at the locations of the annular furnace gas box and the annular mixing gas box. The furnace chamber of the upper section of the DC furnace is connected to the annular furnace gas box and the annular mixing gas box through the air gaps in the permeable walls. A high-temperature mixing gas chamber is provided on the side wall of the annular mixing gas box. At the gas inlet, a furnace temperature measuring thermocouple is inserted above the annular mixing gas box; the upper section of the DC furnace is integrally sealed and installed above the middle section of the DC furnace and fixed with bolts; a tunnel that semi-penetrates the furnace chamber of the upper section of the DC furnace is provided at the lower part of the upper section of the DC furnace, the tunnel starts from the furnace shell and ends in the furnace chamber, and is integrally sealed with the furnace chamber; a DC power conductor, an insulating frame supporting the DC power conductor, and an electrode clamp device are horizontally arranged in the tunnel, and a cathode is vertically installed in the electrode clamp device, the tunnel height is matched with the cathode length and cathode stroke.

[0023] The middle section of the DC furnace is insulated and sealed on the upper plane of the lower section. It has electrode through-holes in its center, surrounded by multiple high-temperature pre-reducing material descending channels. High-temperature furnace gas ascending channels are distributed circumferentially outside these channels. The outer shell of the middle section is a steel shell, while the interior, except for the locations of the holes, is entirely made of high-temperature steel bars and steel fiber reinforced high-temperature refractory material. Embedded heat-resistant pipes and electrode sealing devices are installed in the electrode through-holes. The electrode sealing device comprises three layers of seal: the upper and lower layers are elastic high-temperature fiber felt seals, and the middle layer is a self-aligning graphite seal. The self-aligning graphite seal is annular, with its inner circumference in tight sliding contact with the electrode. Its outer circumference is connected to the pre-embedded heat-resistant pipe via several horizontally radially symmetrically arranged compression springs and insulating material. A pressure plate is provided on the upper surface of the upper seal, and the pressure plate is fixed to the top flange of the pre-embedded heat-resistant pipe. The pressure plate has a through hole in its center, the diameter of which is larger than the cathode diameter. Except for the high-temperature pre-reducing raw material descending channel, the furnace charge in the upper section of the DC furnace is in direct contact with the refractory material in the middle section of the DC furnace. The furnace charge in the high-temperature pre-reducing raw material descending channel is in contact with the material layer in the lower section of the furnace through the high-temperature pre-reducing raw material descending channel set in the middle section.

[0024] The upper part of the lower section of the DC furnace, from the outside to the inside, consists of a furnace shell, high-temperature insulating material, refractory material, and a reaction furnace. The lower part of the lower section of the DC furnace is the furnace bottom, from the outside to the inside, consisting of a furnace shell, high-temperature insulating material, refractory material, and a vertical anode at the furnace bottom. The lower section of the DC furnace is connected to the upper section of the DC furnace through a high-temperature pre-reducing raw material descending channel opened in the middle section of the DC furnace. The upper part of the lower section of the DC furnace has a cathode vertically inserted through an electrode through-hole in the middle section of the DC furnace. A vertical anode is provided at the bottom of the lower section of the DC furnace, and a horizontal anode extending outside the furnace is connected to the bottom of the vertical anode. The reaction furnace, from bottom to top, consists of a permanent anode zone, a metallic phase zone, a slag phase zone, a reaction phase mixing zone, a charge buffer zone, and a furnace gas cavity.

[0025] The furnace gas cavity is a variable cross-section annular furnace gas cavity formed by the furnace wall of the upper part of the lower section of the DC furnace and the natural stacking angle of the raw materials, and a near-quincunx-shaped furnace gas cavity formed by the natural stacking angle of the raw materials flowing out from the high-temperature pre-reduced raw material descending channel at different positions; the near-quincunx-shaped furnace gas cavity is connected to the annular furnace gas cavity; the annular furnace gas cavity is connected to the annular furnace gas box of the upper section of the DC furnace through the high-temperature furnace gas rising channel set in the middle section of the DC furnace; the outer side of the lower section of the DC furnace is provided with an iron tapping port corresponding to the metallic phase region and a slag tapping port corresponding to the reaction phase mixing region.

[0026] The advantages of this invention compared to the prior art are:

[0027] 1) The process flow of this invention reduces the number of steps by 50% and the power capacity of the production line by 80%.

[0028] 2) This invention fully utilizes the physical sensible heat and chemical heat of high-temperature furnace gas to heat raw materials and thermally decompose and pre-reduce furnace charge. The high-temperature furnace gas can be used directly without purification.

[0029] 3) The integrated vertical series double-chamber DC furnace of this invention realizes the integration of five processes: raw material dehydration, raw material heating, raw material thermal decomposition, pre-reduction and direct reduction, and melting. There is no charge transfer process, the charge does not come into contact with the outside air throughout the process, and there is almost no heat loss. Except for the melting process, no external energy is required for the entire process. The physical sensible heat, part of the chemical heat, and the sensible heat of the dust-containing high-temperature furnace gas generated by the reaction itself and the sensible heat of the recovered slag can raise the temperature of the charge entering the lower section of the DC furnace to a high temperature of 800-1200℃. Moreover, all the minerals in the charge are converted into low-valence metal oxides and part of them are converted into metals. Only a small amount of electrical energy needs to be input into the furnace chamber in the lower section of the DC furnace to meet the energy requirements of the smelting process.

[0030] 4) The reaction crucible of this invention has a strong stirring function. Under the impact of a high-speed electron beam of tens of thousands of amperes from top to bottom, the liquid mineral phase and solid coke form strong convection, resulting in excellent kinetic conditions. The redox reaction is completed almost instantaneously. Under strong electromagnetic stirring, the heat transfer rate is fast, the temperature gradient inside the furnace is low, the homogenization time is short, and the temperature of the molten reaction zone is uniform.

[0031] 5) This invention fully utilizes the furnace gas generated by the chemical reaction in the lower section of the DC furnace, which mainly consists of carbon monoxide and hydrogen, to carry out solid-state reduction of elements such as iron and nickel in the raw materials; it also fully utilizes the physical sensible heat and part of the chemical properties of the furnace gas to dehydrate and heat the raw materials, converting high-valence metal oxides into low-valence metal oxides and partially into the metallic phase; and it fully utilizes the physical sensible heat of the slag to produce high-temperature mixed gas, raising the temperature of the combustion air entering the furnace to a high temperature; thereby achieving energy saving, carbon reduction, and emission reduction.

[0032] 6) This invention is simple to control, with only a single series load circuit from the vertical electrode at the bottom of the furnace to the cathode. By simply adjusting the electrode arc voltage, the ratio of the material to the reaction energy can be easily adjusted, making it easy to match the melting speed with the reaction speed.

[0033] 7) This invention has a low failure rate, fewer power equipment throughout the process, and no copper tiles or pressure rings in the high-temperature lower section of the furnace, thus making the entire line more reliable.

[0034] 8) This invention uses solid multilayer high-temperature sealing material to seal the electrode through hole, and uses spring self-aligning and high-elastic material automatic compression self-aligning technology to ensure that the sealing effect remains unchanged when the electrode vibrates during lifting and lowering movements; the device has good sealing performance, is safe and reliable, and does not require investment in large nitrogen generation equipment compressors and pipeline construction.

[0035] 9) The present invention requires less cooling water, and the conductive components (electrode clamps) that need cooling are located outside the furnace. The amount of cooling water required is 70-80% less than that required by conventional copper tiles and pressure rings. Attached Figure Description

[0036] Figure 1 This is a process flow diagram of a low-carbon and energy-saving ore reduction method and apparatus according to the present invention.

[0037] Figure 2 This is a schematic diagram of a vertically connected double-chamber DC furnace in a low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0038] Figure 3 This is a schematic diagram of the cathode sealing between the cathode and the cathode section of the DC furnace in the present invention, which is a low-carbon and energy-saving ore reduction method and apparatus.

[0039] Figure 4This is a cross-sectional schematic diagram of the middle section AA of the vertically connected double-chamber DC furnace in the low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0040] Figure 5 This is an enlarged cross-sectional schematic diagram of the cathode sealing device in the low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0041] Figure 6 This is a cross-sectional schematic diagram of the vertically connected double-chamber DC furnace BB in the ore reduction method and apparatus of the present invention.

[0042] Figure 7 This is a schematic diagram of the lower section of the DC furnace in the ore reduction method and apparatus of the present invention.

[0043] Figure 8 This is a schematic diagram of the slag sensible heat recovery device in the ore reduction method and apparatus of the present invention.

[0044] Figure 9 This is a partially enlarged schematic diagram of the sensible heat recovery device in the low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0045] Figure 10 This is a schematic diagram of a high-frequency molten iron condenser in a low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0046] Figure 11 This is a schematic diagram of the valve core and lever position of the casting station of the high-frequency molten iron condenser in the low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0047] Figure 12 This is a schematic diagram of the valve core and lever positions at the demolding station of a high-frequency molten iron condenser, which is part of a low-carbon and energy-saving ore reduction method and apparatus according to the present invention.

[0048] Figure 13 This is a schematic diagram of the precision rod mold in the low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0049] Figure 14 This is a schematic diagram showing the installation positions of the frame and precision rod-making mold in the ore reduction method and apparatus of the present invention.

[0050] Figure 15 This is a schematic diagram of the installation of valve seat, valve core, valve core lever, and roller in a low-carbon and energy-saving ore reduction method and apparatus of the present invention.

[0051] Figure 16 This is a schematic diagram of the guide rail in a low-carbon and energy-saving ore reduction method and apparatus of the present invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0053] In the description of the embodiments of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "front," and "rear," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationships commonly used when the product is in use. These are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0054] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0055] In the description of the embodiments of the present invention, "multiple" means at least two.

[0056] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0057] Example:

[0058] Combined with appendix Figure 1-16 This embodiment discloses a low-carbon and energy-saving ore reduction method and apparatus. The production method of this embodiment includes the following steps:

[0059] (1) Using the waste heat of furnace gas to remove adsorbed water from raw materials: The raw materials prepared by the batching station are put into the dehydration chamber at the top of the vertical series double-chamber DC furnace; the bottom of the dehydration chamber is connected to the upper section of the DC furnace with a large open size. The mixed raw materials in the chamber are baked by the waste heat of the medium temperature furnace gas in the upper section of the DC furnace. The temperature gradually rises from room temperature to 120℃-250℃. The adsorbed water in the raw materials is converted into steam. The generated water vapor slowly overflows from the material surface of the dehydration chamber, thereby avoiding the water vapor from entering the recovered furnace gas and reducing the calorific value of the furnace gas.

[0060] (2) Use the furnace gas generated by its own reaction to remove the residual water of crystallization in the raw materials and to pre-reduce the metal oxides: blow the high-temperature mixed gas prepared in step (4) into the upper section of the DC furnace; the combustible furnace gas in the furnace gas burns after contacting the mixed gas, releasing a large amount of heat; at the same time, the water vapor in the high-temperature mixed gas reacts with the hot coke to obtain CO and H2, and CO and H2 react with O2 to release heat; the heat obtained from the above reactions together raises the furnace temperature to the required temperature, so that the raw materials in the furnace chamber of the upper section of the DC furnace are heated to above 800°C;

[0061] The chemical reactions that occur in the upper section of the DC furnace include:

[0062] 2CO + O2 = 2CO2↑ (1)

[0063] Fe₂O₃=FeO+O₂↑ (2)

[0064] H2O (g) +C=H2↑+CO↑ (3)

[0065] H2O (g) =H2 (g) +0.5O 2(g) (4)

[0066] H 2(g) +0.5O 2(g) =H2O (g) (5)

[0067] H2O (l) =H2O (g) (6)

[0068] FeO + C = Fe + CO↑ (7)

[0069] FeO + H2 = Fe + H2O (g) ↑ (8)

[0070] The gas generated by the above reaction and the furnace gas that did not participate in the reaction from the lower section 4 of the DC furnace move countercurrently to the furnace charge. During the upward movement of these furnace gases, they continuously exchange heat with the slowly descending furnace charge. When the furnace gas overflows from the surface of the furnace charge in the upper section 2 of the DC furnace in the furnace chamber, the temperature of the furnace gas has dropped to 150 - 250 °C. The furnace gas overflowing from the surface of the furnace charge enters the furnace gas purification system under the suction of the induced draft fan in the purification system; due to the recovery and utilization of the sensible heat of the furnace gas at about 1000 °C in the lower section of the DC furnace and the sensible heat of the high-temperature mixed gas produced by the slag sensible heat recovery device, and using part of the chemical energy of the furnace gas to heat the furnace charge to above 800 °C, and preparing a pre-reduced furnace charge in a low valence state or metal state, this step can achieve a power saving of 20 - 25%;

[0071] (3) Smelting separation and deep reduction: The high-temperature pre-reduced raw materials after the reaction in the upper section of the DC furnace continuously enter the lower section of the DC furnace from the high-temperature pre-reduced raw material descending channel in the middle section of the DC furnace; direct current is introduced into the lower section of the DC furnace. Under the action of a high-power power supply, the temperature of the pre-reduced raw materials rapidly rises to the melting point in the lower section of the DC furnace and quickly melts under the action of the direct current arc; after melting, the metal phase and slag phase in the pre-reduced raw materials are separated, and the slag phase in the pre-reduced raw materials is mixed with the flux to form a new low-melting-point slag phase; the unreduced metal oxides in the low-melting-point slag phase react with coke in a liquid-solid reaction, and after the reaction, a liquid alloy and a waste slag phase with components meeting the product standards are obtained; the following physical and chemical reactions occur in the lower section 4 of the DC furnace. Still taking chromite as an example:

[0072] Fe (S) =Fe (l) (9)

[0073] FeO (S) =FeO (l) (10)

[0074] Cr2O 3(S) =Cr2O 3(l) (11)

[0075] FeO + C = Fe + CO↑ (12)

[0076] △G° = 148003.38 - 150.31T; T 开 =985K

[0077] 2 / 3Cr2O3 + 26 / 9C = 4 / 9Cr3C2 + 2CO↑ (13)

[0078] △G° = 114410 - 83.05T Tstart = 1373K

[0079] 2 / 3Cr2O3 + 18 / 7C = 4 / 21Cr7C3 + 2CO↑ (14)

[0080] △G° = 115380 - 82.09T T 开 = 1403K

[0081] 2 / 3Cr2O3 + 54 / 23C = 4 / 69Cr 23 C6 + 2CO↑ (15)

[0082] △G° = 118270 - 81.75T; T onset = 1448K

[0083] 2 / 3Cr2O3, + 2C = 4 / 3Cr + 2CO↑ (16)

[0084] △G° = 123970 - 81.22T; T onset = 1523K

[0085] 14 / 5Cr3C 2(l) + 2 / 3Cr2O 3(l) = 4 / 3Cr (l) + 6 / 5Cr7C 3(l) + 2CO↑ (17)

[0086] △G° = 130050 - 74.03T; T onset = 1763K

[0087] Due to the rapid temperature rise of the raw materials to the melting point, rapid heating and rapid reaction in the lower section of the DC furnace, the above reactions will mainly be (15) and (16), and finally the product will have a lower carbon content. Also, due to the vertical directional convection movement of the molten iron and slag in the reaction zone and the formation zone, the small bubbles and oxidation inclusions in the molten iron are more easily adsorbed by the slag or float to the surface and be discharged. Therefore, the main element content of the product is higher, the oxygen content is lower, the bubbles and inclusions are fewer, and the quality is better;

[0088] The reaction produces a liquid alloy, liquid slag and high-temperature furnace gas mainly composed of CO with compositions meeting the design requirements;

[0089] (4) Producing a mixed high-temperature gas: Transfer the liquid slag obtained in step (3) to the adiabatic container 36 of the slag sensible heat recovery device; in the adiabatic container 36, the small amount of metal phase existing in the liquid slag will be completely separated from the liquid slag. After separation, the metal phase precipitates at the bottom of the adiabatic container 36, and the slag phase floats on the surface of the metal phase; the separated liquid slag phase is used to provide heat energy for producing the mixed high-temperature gas and for producing granular products such as refractory sand and construction sand; the metal phase is discharged at intervals from the liquid alloy outlet pipe at the bottom of the device;

[0090] Production process: Input a control signal to move the lifting device 37.9 at the bottom of the insulated container 36 downward to the set position, and the circular cone 37.2 moves downward synchronously by an equal distance; at this time, liquid sludge will flow out from the circular cone 37.2; start the rotation drive device to drive the circular cone 37.2 to rotate at high speed, and the liquid sludge will disperse and fly out from the centrifugal half hole of the circular cone 37.2 as droplets; while the circular cone 37.2 moves downward synchronously, high-pressure air and high-pressure water are introduced; the droplets undergo strong heat exchange with the high-pressure air and water mist, resulting in the water mist vaporizing into high-temperature water vapor, and the high-pressure air being heated into high-temperature gas; the droplets are transformed into low-temperature granular products;

[0091] The physical and chemical changes that occur during this process are as follows:

[0092] H2O (l) =H2O (g) (Main Change)

[0093] H2O (g) =H2 + 0.5O2 (small amount)

[0094] Normal temperature air → High temperature air

[0095] High-temperature liquid slag → low-temperature granular solid product

[0096] This process produces a mixture of high-temperature gas (air, water vapor, and hydrogen) and granular solid products at temperatures exceeding 700°C.

[0097] Under the pressure of a high-pressure blower, the mixed high-temperature gas is transported through a cyclone separator and insulated pipes to the input interface of the annular mixing gas box in the upper section of the once-through furnace.

[0098] (5) The liquid alloy obtained in step (3) is continuously injected into the high-frequency molten iron condenser at a constant flow rate; the high-frequency molten iron condenser has dozens to hundreds of fast-solidifying precision rod molds 53, and the precision rod molds 53 are circulated with a high-speed cooling medium, which can make the liquid solidify quickly; the inner cavity of the precision rod mold 53 is a frustum shape with a smaller top and a larger bottom; after one precision rod mold 53 is filled with molten iron, it automatically rotates out of the casting station under the action of the drive mechanism 50, and the next precision rod mold 53 is simultaneously rotated into the casting station; this cycle continues until all casting is completed; when the solidified round rod is rotated to the demolding station, it will automatically fall off, and after cooling, the product required by the user is obtained; The high-frequency molten iron condenser features high-frequency vibration, maintaining constant vibration throughout the casting process. Its functions are threefold: first, to accelerate the solidification of high-temperature molten iron, refine grain size, and improve product quality; second, to maintain relative movement between the precision mold and the injected molten iron, preventing the high-temperature liquid metal from adhering to the mold wall and ensuring a slight separation between the cast rod and the mold; and third, to facilitate the detachment of the solidified cast rod from the mold. The vibration frequency of this high-frequency molten iron condenser is 50-10000Hz. The drive mechanism drives the frame to rotate intermittently. The frame, via spring steel plates, drives the platform in a periodic "stop-rotate-stop" rotation, with a rotation cycle of 0.5-5 seconds. The inner diameter of the inner mold of the rod-making die... The height of the rod-making mold is 300-1500mm.

[0099] (6) Intelligent control

[0100] 1) Dewatering bin level control: When the material level measuring instrument detects that the raw material level is lower than the lower limit, the external feeding device automatically replenishes the material in the bin;

[0101] 2) Furnace gas flow control: The furnace gas purification system uses a variable frequency induced draft fan. When the furnace gas flow detector in the dehydration chamber detects the passage of furnace gas, the speed of the induced draft fan in the purification system is increased; when the furnace gas flow detector in the dehydration chamber detects the reverse flow of cold air, the speed of the induced draft fan in the purification system is reduced.

[0102] 3) High-temperature mixed gas control: When the temperature sensor in the upper section of the DC furnace detects a temperature lower than the set temperature, the high-pressure air flow rate of the slag sensible heat recovery device is increased while the high-pressure water flow rate is reduced; conversely, the high-pressure air flow rate is reduced while the high-pressure water flow rate is increased.

[0103] 4) DC parameter control: When the molten iron temperature is too low and the metal recovery rate decreases, reduce the DC voltage while keeping the power fed into the furnace constant; when the molten iron temperature is too high and the smelting power consumption increases, reduce the DC voltage, raise the electrodes, and keep the power fed into the furnace constant.

[0104] The apparatus used in the above method includes a vertically connected double-chamber DC furnace, and a slag sensible heat recovery device including an insulated container and a high-frequency molten iron condenser.

[0105] The vertically connected double-chamber direct current furnace includes a dehydration chamber 1, an upper section 2, a middle section 3, and a lower section 4 arranged from top to bottom. The dehydration chamber 1 is directly fixed to the top plate of the upper section 2 of the direct current furnace. It is shaped like an inverted truncated cone, without a cover plate or bottom plate. A material level detector 34 is installed on the top, and a furnace gas detector 35 is installed inside the chamber. The functions of the dehydration chamber 1 are: first, to receive raw materials; second, to dry the furnace charge with the waste heat of the furnace gas and remove the adsorbed water from the furnace charge, allowing the adsorbed water to overflow from the top of the chamber, thus preventing water vapor from mixing into the externally supplied furnace gas, i.e., raw coal gas, thereby improving the purity of the furnace gas; and third, to lock the air. By setting a reasonable material level height, the geometric specifications of the inverted cone, and controlling the speed of the induced draft fan of the furnace gas purifier, it can prevent the furnace gas from overflowing from the top surface of the dehydration chamber 1, as well as prevent cold air and water vapor generated during dehydration in the dehydration chamber 1 from entering the furnace gas.

[0106] A furnace gas outlet 5 is provided at the top of the upper section 2 of the DC furnace, and a No. 2 furnace gas temperature and flow detector 63 is installed at the furnace gas outlet 5; an annular furnace gas box 10 and an annular mixing gas box 11 are arranged from bottom to top on the outer side of the bottom of the upper section 2 of the DC furnace; the furnace chamber of the upper section 2 of the DC furnace is a bottomless furnace chamber; a refractory material layer 6 is provided on the inner wall of the furnace shell of the upper section 2 of the DC furnace, and a permeable wall 12 is provided at the annular furnace gas box 10 and the annular mixing gas box 11; the furnace chamber of the upper section 2 of the DC furnace is connected to the annular furnace gas box 10 and the annular mixing gas box 11 through the air gap of the permeable wall 12; a high temperature mixing gas box 11 is provided on the side wall of the annular mixing gas box 11. A gas inlet 16 is connected to a furnace temperature measuring thermocouple 64 above the annular mixing box 11; the upper section 2 of the DC furnace is installed in a sealed manner above the middle section 3 of the DC furnace and fixed with bolts; a tunnel 8 that semi-penetrates the furnace chamber of the upper section 2 of the DC furnace is provided in the lower part of the upper section 2 of the DC furnace, the tunnel 8 starts from the furnace shell and ends in the furnace chamber, and is completely sealed with the furnace chamber; a DC power conductor 65, an insulating frame supporting the DC power conductor 65 and an electrode clamp device 27 are horizontally arranged in the tunnel 8, and a cathode 9 is vertically installed in the electrode clamp device 27; the height of the tunnel 8 matches the length and stroke of the cathode 9.

[0107] The functions of the upper section 2 of the DC furnace are: first, to seamlessly receive the dehydrated furnace charge from the dehydration furnace; second, to transfer the waste heat of the flue gas to the furnace charge in the dehydration chamber 1; third, to remove the residual crystal water in the furnace charge by using the sensible heat and chemical heat of the high-temperature furnace gas generated in the lower section 4 of the DC furnace and the high-temperature mixed gas produced by the slag recovery device; fourth, to heat the raw materials to the set high temperature and decompose high-valence oxides into low-valence oxides; and fifth, to use the reducing properties of the furnace gas to reduce easily reducible metal oxides into metals and reduce incompletely decomposed high-valence oxides into low-valence oxides.

[0108] The middle section 3 of the DC furnace is insulated and sealed on the upper surface of the lower section 4 of the DC furnace. It has an electrode through hole 66 in the middle. There are multiple high-temperature pre-reducing raw material descending channels 13 around the electrode through hole 66. High-temperature furnace gas rising channels 14 are distributed circumferentially outside the high-temperature pre-reducing raw material descending channels 13. The middle section 3 of the DC furnace is connected to a No. 1 furnace gas temperature and flow detector 15. The outer shell of the middle section 3 of the DC furnace is a steel shell. Except for the positions of the holes, the interior is entirely made of high-temperature steel bars and steel fiber reinforced high-temperature refractory material 7. An electrode sealing device is set in the electrode through hole 66. The electrode sealing device includes a self-aligning graphite seal 28 set on the part of the cathode 9 that penetrates the high-temperature bridging material layer 7. The self-aligning graphite seal 28 is connected to the heat-resistant tube 31 through a compression spring 29 and an insulating material 30. The top of the heat-resistant tube 31 extends out of the high-temperature bridging material layer 7 and is connected to the sealing pressure plate 32. The space between the heat-resistant tube 31 and the cathode 9 is filled with high-density alumina fiber felt 33.

[0109] The functions of the middle section 3 of the DC furnace are: first, to bear the mass of the furnace body containing the furnace charge in the upper section 2 of the DC furnace; second, to allow the cathode 9 to be inserted into the furnace chamber of the lower section 4 of the DC furnace in a sealed manner; third, to transfer the high-temperature pre-reduction furnace charge produced in the upper section 2 of the DC furnace to the furnace chamber of the lower section 4 of the DC furnace with almost no heat loss; and fourth, to directly transport the dust-containing high-temperature furnace gas to the annular furnace gas box 10 of the upper section 2 of the DC furnace without loss.

[0110] Except for the high-temperature pre-reducing raw material descending channel 13, the furnace charge in the upper section 2 of the DC furnace is in direct contact with the refractory material in the middle section 3 of the DC furnace. The furnace charge in the high-temperature pre-reducing raw material descending channel 13 is in contact with the material layer in the lower section of the DC furnace through the high-temperature pre-reducing raw material descending channel 13 set in the middle section.

[0111] The upper part of the lower section 4 of the DC furnace is the furnace chamber, which consists of the furnace shell, high-temperature insulating material 17, refractory material 18, and reaction furnace chamber 19 from the outside to the inside; the lower part is the furnace bottom, which consists of the furnace shell, high-temperature insulating material 17, refractory material 18, and anode 20 from the outside to the inside; the furnace chamber of the lower section 4 of the DC furnace is connected to the furnace chamber of the upper section 2 of the DC furnace through the high-temperature pre-reducing raw material descending channel 13 opened in the middle section 3 of the DC furnace; the upper part of the furnace chamber of the lower section 4 of the DC furnace has the cathode 9 vertically inserted through the electrode through hole 66 of the middle section 3 of the DC furnace; the bottom of the furnace chamber of the lower section 4 of the DC furnace is provided with a vertical anode 20 corresponding to the cathode 9, and a horizontal anode extending out of the furnace is connected to the bottom of the vertical anode 20; the reaction furnace chamber 19 is provided with a permanent anode area 21, a metallic phase area 22, a slag phase area 23, a reaction phase mixing area 24, a charge buffer area 67, and a furnace gas cavity 68 from bottom to top;

[0112] The furnace gas cavity 68 is a variable cross-section annular furnace gas cavity 69 formed by the furnace wall above the lower section 4 of the DC furnace and the natural stacking angle of the raw materials, and a near-quincunx-shaped furnace gas cavity formed by the natural stacking angle of the raw materials flowing out from the high-temperature pre-reduced raw material descending channel 13 at different positions; the near-quincunx-shaped furnace gas cavity is connected to the annular furnace gas cavity 69; the annular furnace gas cavity 69 is connected to the annular furnace gas box 10 of the upper section 2 of the DC furnace through the high-temperature furnace gas rising channel 14 set in the middle section 3 of the DC furnace; the lower section 4 of the DC furnace is provided with an iron tapping port 25 corresponding to the metal phase region 22 and a slag tapping port 26 corresponding to the slag phase region 23.

[0113] The slag sensible heat recovery device includes an insulated container 36, a heat exchanger 37, and a gravity separator 38. The insulated container 36 has an insulation cover 39 on top and a boss 40 on the bottom. A refractory tube 43, penetrating the bottom of the insulated container 36, is vertically installed at the center of the boss 40. The upper surface of the refractory tube 43 is flush with the boss 40, and its lower end passes through the shell of the heat exchanger 37 into the heat exchange chamber 42. The boss 40 allows denser molten metal droplets to be stored at the bottom of the insulated container 36, preventing molten metal from flowing into the refractory tube 43, thus separating the slag from the metal. The heat exchanger 37 consists of a heat exchange chamber shell 37.1, a circular cone 37.2, a frequency converter 37.3, and a lifting device 38 that drives the frequency converter 37.3 to move up and down. 7.9 Composition: The heat exchange chamber shell 37.1 is located directly below the insulation container 36. Multiple high-pressure water nozzles are mounted on the top plate, with high-pressure water pipes 37.4 connected to the nozzle interfaces. A high-pressure air interface 37.5 is installed on one side of the heat exchange chamber shell 37.1, and a gas-slag mixture output interface is on the other side. A circular hole 37.6 is opened in the bottom plate. A circular cone 37.2 is installed in the space between the top and bottom plates of the heat exchange chamber shell 37.1. A frequency converter drive 37.3 is installed directly below the heat exchange chamber shell 37.1. Its drive shaft passes through the circular hole 37.6 in the bottom plate of the heat exchange chamber shell 37.1 and is inserted into the heat exchange chamber 42, connecting to the circular cone 37.2. A space is provided between the circular hole 37.6 in the bottom plate and the drive shaft 37.7 of the circular cone 37.2. The sealing material and the frequency converter drive 37.3 drive the circular cone 37.2 to rotate horizontally, which disperses the liquid slag. The outer edge of the circular cone 37.2 is provided with a semi-circular hole 37.8 for centrifugal dispersing of liquid slag. The lifting device 37.9 is located directly below the frequency converter drive 37.3. When the circular cone 37.2 moves up and down driven by the lifting device 37.9, it acts as a valve. When the circular cone 37.2 moves upward and is in contact with the bottom outlet of the refractory tube 43, the liquid waste slag is shut off and cannot flow out. When it moves downward, the circular cone 37.2 separates from the bottom outlet of the refractory tube 43, and the liquid waste slag 41 flows out from the bottom outlet of the refractory tube 43. The gas-slag mixture output interface of the heat exchange chamber 42 shell is connected to the heavy-duty pipe 37.10. The gravity separator 38 is connected; the upper part of the gravity separator 38 is a cylindrical container with a mixed gas pipe 44 vertically installed in the center. The mixed gas pipe 44 extends from the top of the gravity separator 38 and is then connected to the interface of the annular mixed gas box 11 of the upper section 2 of the DC furnace through an insulated air pipe; the lower part of the gravity separator 38 is an inverted frustum-shaped container. A plate heat exchanger 45 is installed inside the inverted frustum-shaped container. The air interface of the plate heat exchanger 45 is connected to a high-pressure blower, and the outlet is connected to the high-pressure air interface 37.5 of the heat exchanger through a hot air pipe 46. The gaps of the plate heat exchanger 45 are filled with hot solid slag particles 47 moving from top to bottom; the bottom surface of the insulated container 36 is provided with an insulation material layer 47 and a refractory material layer 48 from bottom to top.

[0114] The high-frequency molten iron condenser includes a frame 49, a drive mechanism 50 supporting and driving the frame 49 to rotate, spring steel plates 51, a platform 52, a precision bar-making mold 53, an annular pouring cup 54, a bottom valve 55, a high-frequency vibrator 56, and a molten iron cleaning machine 57. The platform 52 is circumferentially connected to the outer edge of the frame 49 via multiple sets of spring steel plates 51. An annular base plate 52.1 is provided at the bottom of the platform 52, and an annular panel 52.2 is provided at the top. A cylindrical connecting plate 52.3 is provided between the annular panel 52.2 and the annular base plate 52.1. One side of the cylindrical connecting plate 52.3 is connected to the spring steel plate 51 via an inner flange plate 52.4, and the other side is provided with a bar-making mold mounting position 52.5. A spring assembly fixing hole 52.6 is provided on the inner flange plate 52.4. The annular base plate 52.1... The frame 52 is equipped with a rod demolding hole 52.7, a tie rod screw hole 52.8, and a bottom valve seat positioning screw hole 52.9. Cooling water pipe passage holes 52.10 are provided at both the top and bottom of the cylindrical connecting plate 52.3. Dozens to hundreds of precision rod molds 53 are mounted on the frame 52. The bottom plane of the precision rod mold 53 is mounted on the upper plane of the annular base plate 52.1. The height from the upper plane of the annular base plate 52.1 to the annular panel 52.2 is equal to the height of the rod mold. The bottom plane of the annular pouring cup 54, fixed to the annular panel 52.2, is pressed against the upper plane of the precision rod mold 53 by bolts and tie rods 53. The bottom of the annular pouring cup 54 has a through hole consistent with the mold position. The annular pouring cup 54 holds liquid alloy from a ladle or other container and injects the liquid alloy into the precision rod mold through the through hole. The precision rod mold 53 has a rod release hole 52.7 at the corresponding position of the annular base plate 52.1. The rod release hole 52.7 is coaxial with the rod mold and its diameter is larger than the maximum diameter of the rod. The bottom valve 55 includes a valve seat 55.1, a positioning pin 55.2 for the valve seat 55.1, a compression spring 55.3 for the valve seat 55.1, a valve core 55.4, a valve core lever 55.5, a roller 55.6, and a guide rail 55.7. The bottom valve 55 is installed directly below the annular base plate 52.1 corresponding to the mold position. The valve seat 55.1 is provided with a positioning hole 55.1.1, a valve core hole 55.1.2, and a lever groove 55.1.3. The positioning pin 55.2 passes through the positioning hole 55.1.1 of the valve seat 55.1 and is then vertically screwed into the bottom plane of the annular base plate 52.1. The valve seat 55.1 is in close contact with the bottom plane of the annular base plate 52.1 by the elastic force of the compression spring 55.3 through the screw hole 52.9. A valve core 55.4 is installed inside the valve seat 55.1, and a valve core lever 55.5 is installed on the valve core 55.4. The compression spring 55.3 is vertically positioned between the lower plane of the valve seat 55.1 and the upper plane of the guide rail 55.7. The upper plane of the compression spring 55.3 presses against the bottom plane of the valve seat 55.1, and the lower plane of the compression spring 55.3 presses against the upper plane of the guide rail 55.7. The guide rail 55.7 is located below the compression spring 55.3 and is horizontally fixed to the guide rail base plane. The guide rail 55.7 is an annular planar thick plate with a locally outwardly gradually displaced shape. A closed-loop guide rail groove 55.8 is provided on the upper surface of the annular planar thick plate.8. The guide rail 55.7 gradually shifts outwards smoothly; all rollers 55.6 connected to the valve core levers 55.5 are set in the guide rail grooves 55.8; several high-frequency vibrators 56 are set on the frame 52, with a vibration frequency of 50-10000Hz; the molten iron cleaning machine 57 includes a molten iron cleaning machine bracket independently fixed outside the outer circumference of the frame 52, and the cleaning blade 57.1 of the molten iron cleaning machine 57 extends into the annular pouring cup, with the bottom plane and side of the blade respectively clearance-fitted with the bottom and side of the pouring cup to prevent iron particles from sticking to the inner cavity of the pouring cup; the drive mechanism 50 drives the frame 49, and the frame 49 drives the frame 52 to perform a periodic intermittent rotation of "stop-rotate-stop" through the spring steel plate 51, with an indexing period of 0.5-5S (corresponding to a frequency of 2-0.2Hz), of which the stopping time accounts for 70%-85% of the periodic time and the indexing time accounts for 15%-30% of the periodic time. .

[0115] Between several mold positions before and after the demolding station, the centerline trajectory of the guide rail groove 55.8 deviates from the planar projection circle of the centerline of the precision rod mold 53, causing the roller 55.6 to drive the valve core lever 55.5 to move, so that the valve core 55.4 is in a state of gradual opening or gradual closing. When it moves to the demolding station, the valve core 55.4 is in a fully open state. Outside of several mold positions before and after the demolding station, the centerline circle of the guide rail groove 55.8 coincides with the planar projection circle of the centerline of the precision rod mold 53, so that the valve core 55.4 is in a static closed state.

[0116] The precision rod-making mold 53 includes an inner mold 53.1 and an outer mold 53.2 spaced apart. A cooling water channel 53.3 is formed between the inner mold 53.1 and the outer mold 53.2. A cooling water inlet pipe 53.4 communicating with the cooling water channel 53.3 is provided at the top of the precision rod-making mold 53, and a cooling water outlet pipe 53.5 communicating with the cooling water channel 53.3 is provided at the bottom. A sealing ring 53.6 is provided between the tops of the inner mold 53.1 and the outer mold 53.2.

[0117] I. Example (Smelting FeMn68Si18) Parameters and Implementation Results:

[0118] (1) Raw material conditions:

[0119] The overall composition of the raw materials after mixing is shown in Table 1:

[0120] Table 1

[0121]

[0122] (2) The system operating parameters and operating results are shown in Table 2:

[0123] Table 2

[0124]

[0125]

[0126]

[0127] II. The present invention achieves the following technical effects compared to the prior art:

[0128] (1) The comprehensive energy consumption limit for FeMn68Si18 at the first-level standard specified in GB 31341-2017 is 860 kgce / t, and the smelting power consumption per unit product is 3800 kWh / t. The most advanced domestic level generally cannot reach the first-level standard of this invention. The power consumption per unit product of this invention is 2811-3013 kWh / t, and the comprehensive energy consumption per ton of product is 779-819 kgce (excluding the standard coal equivalent of recovered furnace gas), which are 20.71%-26.03% and 4.72-9.41% lower than the national first-level energy consumption limit, respectively; the recovered furnace gas (coal gas) per unit product is 1000 Nm³. 3 / t, calorific value 4500-5500 kJ / Nm 3 The unit product recovered furnace gas is equivalent to 154-188 kgce / t of standard coal; if the output coal gas is considered, the comprehensive energy consumption is about 630 kgce / t, which is 26.65% lower than the first-level limit.

[0129] (2) The coke consumption per unit FeMn68Si18 alloy molten iron is 439-463 kg / t, which is 7.4-12.2% lower than the domestic counterparts' 500 kg / t; the manganese metal recovery rate is 87.86-93.21%, which is 2.86-8.21% higher than the domestic advanced level of 85%; and the molten iron yield is increased by 4.36-5.21%.

[0130] (3) The high-temperature furnace gas at a temperature of about 1000℃ is used directly for pre-reduction or heat exchange with the cold material in the upper furnace. Its exhaust temperature is less than 300℃. The physical sensible heat of the furnace gas recovered per ton of FeMn68Si18 product is 97-108kJ / t, which is equivalent to 33-37kg of standard coal.

[0131] (4) High-temperature mixed gas at 650-710℃ is obtained by quenching liquid high-temperature slag with high-pressure air and water mist. The high-temperature mixed gas is directly used to assist the combustion of reducing gas in the upper section of the furnace and to pre-reduce iron oxide in the furnace charge, thereby recovering 151-165 kJ / t of physical sensible heat of slag, equivalent to 51-56 kg of standard coal.

[0132] (5) Molten iron is directly cast into high-quality rod-shaped products with fast cooling speed, dense structure and low powdering rate. There is almost no splashing during the molten iron casting process. The yield of molten iron is 97.36-98.21%, which is 4.36-5.21% higher than the domestic advanced level of 93%, and reduces the energy consumption of qualified products by about 72 kgce / t.

[0133] (6) The material layer thickness in the lower section of the DC furnace is thinner than that of conventional methods. The large amount of reducing gas generated by reduction can pass through the material layer smoothly, avoiding "slag overturning". Therefore, low-grade raw materials, powders and low-strength reducing agents can be used.

[0134] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A low-carbon and energy-saving ore reduction method, characterized in that, Includes the following steps: (1) Using the waste heat of furnace gas to remove adsorbed water from raw materials: The raw materials prepared by the batching station are put into the dehydration chamber at the top of the vertical series double-chamber DC furnace; the bottom of the dehydration chamber is connected to the upper section of the DC furnace with a large open size. The mixed raw materials in the chamber are baked by the waste heat of the medium temperature furnace gas in the upper section of the DC furnace. The temperature gradually rises from room temperature to 120℃-250℃. The adsorbed water in the raw materials is converted into steam, and the generated water vapor slowly overflows from the surface of the dehydration chamber. (2) Use the furnace gas generated by its own reaction to remove the residual water of crystallization in the raw materials and to pre-reduce the metal oxides: blow the high-temperature mixed gas prepared in step (4) into the upper section of the DC furnace; the combustible furnace gas in the furnace gas comes into contact with the mixed gas and burns, releasing a large amount of heat; through the combustion of the furnace gas and the combustion of CO and H2 generated by the reaction of the mixed gas in the upper section of the DC furnace, the raw materials in the furnace are heated to above 800°C; in the upper section of the DC furnace, the furnace charge moves from top to bottom and the furnace gas moves from bottom to top in a countercurrent motion, and the furnace gas overflows from the furnace surface and enters the furnace gas purification system from the top of the furnace; (3) Melting and deep reduction: The high-temperature pre-reducing raw material after the reaction in the upper section of the DC furnace continuously enters the lower section of the DC furnace from the high-temperature pre-reducing raw material descending channel in the middle section of the DC furnace; DC power is applied to the lower section of the DC furnace, and under the action of the high-power power supply, the temperature of the pre-reducing raw material in the lower section of the DC furnace rises rapidly to the melting point and melts rapidly under the action of DC arc; after melting, the metal phase and slag phase in the pre-reducing raw material separate, and the slag phase in the pre-reducing raw material mixes with the flux to form a new low-melting-point slag phase; the unreduced metal oxides in the low-melting-point slag phase undergo a liquid-solid reaction with coke, and after the reaction, a liquid alloy with a composition that meets the product standard, a discarded slag phase, and a high-temperature furnace gas mainly composed of CO are obtained; (4) Preparation of mixed high-temperature gas: The liquid slag obtained in step (3) is transported to the insulated container of the slag sensible heat recovery device; high-pressure air and high-pressure water mist are introduced into the heat exchanger chamber of the recovery device. The high-pressure air and high-pressure water mist undergo intense heat exchange with the slag in the heat exchanger chamber, resulting in the water mist being vaporized into high-temperature water vapor and the high-pressure air being heated into high-temperature gas. The slag is transformed into low-temperature granular products; the high-temperature mixed gas is directly transported to the upper section of the DC furnace for use; in the insulated container, the small amount of metal phase in the liquid slag will be completely separated from the liquid slag phase. After separation, the metal phase precipitates at the bottom of the insulated container and is discharged from the liquid alloy outlet pipe at the bottom of the device after a period of time. After solidification and cooling, qualified products are obtained. (5) The liquid alloy obtained in step (3) is continuously injected into a high-frequency molten iron condenser at a constant flow rate; the high-frequency molten iron condenser has dozens to hundreds of fast-solidifying precision rod molds, and the precision rod molds are circulated with a high-speed cooling medium, which can make the liquid solidify quickly; the inner cavity of the precision rod mold is a frustum shape with a smaller upper part and a larger lower part; after a precision rod mold is filled with molten iron, it is automatically rotated out of the casting station under the action of the drive mechanism, and the next precision rod mold is simultaneously rotated into the casting station; before rotating into the casting station, a certain amount of alloy powder is added through an external powder adding device. The material is added to the bottom of the mold cavity inside the rod-making mold; this cycle continues until all casting is complete; the solidified round rod automatically detaches when rotated to the demolding station, and after cooling, the product required by the user is obtained; the high-frequency molten iron condenser has a high-frequency vibration function, vibrating throughout the casting process; the vibration frequency of this high-frequency molten iron condenser is 50-10000Hz, the drive mechanism drives the frame to rotate intermittently, and the frame drives the platform to rotate periodically in a "stop-rotate-stop" cycle through spring steel plates, with an indexing cycle of 0.5-5 seconds, and the inner diameter of the rod-making mold... The height of the rod-making mold is 300-1500mm.

2. The low-carbon and energy-saving ore reduction method according to claim 1, characterized in that, The vertically connected double-chamber DC furnace includes a dehydration chamber, an upper section of the DC furnace, a middle section of the DC furnace, and a lower section of the DC furnace arranged from top to bottom. The dehydration chamber is directly fixed to the top plate of the upper section of the DC furnace, without a cover plate or bottom plate. A material level detector is installed on its top, and a furnace gas detector is installed inside the chamber. The upper section of the DC furnace has a furnace gas outlet at its top, and a No. 2 furnace gas temperature and flow meter is installed at the furnace gas outlet. From bottom to top, an annular furnace gas box and an annular mixing gas box are arranged on the outer bottom of the upper section of the DC furnace. The furnace chamber of the upper section of the DC furnace is a bottomless furnace chamber. A refractory material layer is provided on the inner wall of the furnace shell of the upper section of the DC furnace, and permeable walls are provided at the locations of the annular furnace gas box and the annular mixing gas box. The furnace chamber of the upper section of the DC furnace is connected to the annular furnace gas box and the annular mixing gas box through the air gaps in the permeable walls. A high-temperature mixing gas chamber is provided on the side wall of the annular mixing gas box. At the gas inlet, a furnace temperature measuring thermocouple is inserted above the annular mixing gas box; the upper section of the DC furnace is integrally sealed and installed above the middle section of the DC furnace and fixed with bolts; a tunnel that semi-penetrates the furnace chamber of the upper section of the DC furnace is provided at the lower part of the upper section of the DC furnace, the tunnel starts from the furnace shell and ends in the furnace chamber, and the tunnel is integrally sealed with the furnace chamber; a DC power conductor, an insulating frame supporting the DC power conductor, and an electrode clamping device are horizontally arranged in the tunnel, and a cathode is vertically installed in the electrode clamping device, the tunnel height is matched with the cathode length and cathode stroke.

3. The low-carbon and energy-saving ore reduction method according to claim 2, characterized in that, The middle section of the DC furnace is insulated and sealed on the upper plane of the lower section. It has electrode through-holes in its center, surrounded by multiple high-temperature pre-reducing material descending channels. High-temperature furnace gas ascending channels are distributed circumferentially outside these channels. The outer shell of the middle section is a steel shell, while the interior, except for the locations of the holes, is entirely made of high-temperature steel bars and steel fiber reinforced high-temperature refractory material. Embedded heat-resistant pipes and electrode sealing devices are installed in the electrode through-holes. The electrode sealing device comprises three layers of seal: the upper and lower layers are elastic high-temperature fiber felt seals, and the middle layer is a self-aligning graphite seal. The self-aligning graphite seal is annular, with its inner circumference in tight sliding contact with the electrode. Its outer circumference is connected to the pre-embedded heat-resistant pipe via several horizontally radially symmetrically arranged compression springs and insulating material. A pressure plate is provided on the upper surface of the upper seal, and the pressure plate is fixed to the top flange of the pre-embedded heat-resistant pipe. The center of the pressure plate is in a through hole, the diameter of which is larger than the cathode diameter. Except for the high-temperature pre-reducing raw material descending channel, the furnace charge in the upper section of the DC furnace is in direct contact with the refractory material in the middle section of the DC furnace. The furnace charge in the high-temperature pre-reducing raw material descending channel is in contact with the material layer in the lower section of the furnace through the high-temperature pre-reducing raw material descending channel set in the middle section.

4. The low-carbon and energy-saving ore reduction method according to claim 2, characterized in that, The upper part of the lower section of the DC furnace, from the outside to the inside, consists of a furnace shell, high-temperature insulating material, refractory material, and a reaction furnace. The lower part of the lower section of the DC furnace is the furnace bottom, from the outside to the inside, consisting of a furnace shell, high-temperature insulating material, refractory material, and a vertical anode at the furnace bottom. The lower section of the DC furnace is connected to the upper section of the DC furnace through a high-temperature pre-reducing raw material descending channel opened in the middle section of the DC furnace. The upper part of the lower section of the DC furnace has a cathode vertically inserted through an electrode through-hole in the middle section of the DC furnace. A vertical anode is provided at the bottom of the lower section of the DC furnace, and a horizontal anode extending outside the furnace is connected to the bottom of the vertical anode. The reaction furnace, from bottom to top, consists of a permanent anode zone, a metallic phase zone, a slag phase zone, a reaction phase mixing zone, a charge buffer zone, and a furnace gas cavity.

5. The low-carbon and energy-saving ore reduction method according to claim 4, characterized in that, The furnace gas cavity is a variable cross-section annular furnace gas cavity formed by the furnace wall of the upper part of the lower section of the DC furnace and the natural stacking angle of the raw materials, and a near-quincunx-shaped furnace gas cavity formed by the natural stacking angle of the raw materials flowing out from the high-temperature pre-reduced raw material descending channel at different positions; the near-quincunx-shaped furnace gas cavity is connected to the annular furnace gas cavity; the annular furnace gas cavity is connected to the annular furnace gas box of the upper section of the DC furnace through the high-temperature furnace gas rising channel set in the middle section of the DC furnace; the outer side of the lower section of the DC furnace is provided with an iron tapping port corresponding to the metallic phase region and a slag tapping port corresponding to the reaction phase mixing region.

6. The low-carbon and energy-saving ore reduction method according to claim 1, characterized in that, The slag sensible heat recovery device includes an insulated container, a heat exchanger, and a gravity separator. The insulated container has an insulated cover on top and a boss at the bottom. A refractory pipe is vertically installed at the center of the boss, penetrating the bottom of the insulated container. The upper surface of the refractory pipe is flush with the boss, and its lower end passes through the heat exchanger shell and enters the heat exchange chamber in a sealed manner. The heat exchanger consists of a heat exchange chamber shell, a circular cone, a frequency converter, and a lifting device that drives the frequency converter up and down. The heat exchange chamber shell is located directly below the insulated container. Multiple high-pressure water nozzles are installed on the top plate, with high-pressure water pipes connected to the nozzle interfaces. A high-pressure air interface is installed on one side of the heat exchange chamber shell, and a gas-slag mixture output interface is located on the other side. The bottom plate has a circular hole; a circular cone is installed in the space between the top and bottom plates of the heat exchange chamber shell, and a semi-circular hole for liquid-sludge centrifugation is provided on the outer edge of the circular cone; a frequency converter is installed directly below the heat exchange chamber shell, and its drive shaft passes through the circular hole in the bottom plate of the heat exchange chamber shell and is inserted into the heat exchange chamber to connect with the circular cone. A sealing material is provided between the circular hole in the bottom plate and the drive shaft of the circular cone. The frequency converter drives the circular cone to rotate horizontally; a lifting device is located directly below the frequency converter and acts as a valve when the circular cone is driven to move up and down by the lifting device; the gas-sludge mixture output interface of the heat exchange chamber shell is connected to the gravity separator through an insulation pipe.

7. The low-carbon and energy-saving ore reduction method according to claim 6, characterized in that, The upper part of the gravity separator is a cylindrical container with a mixed gas pipe vertically installed at its center. The mixed gas pipe extends from the top of the gravity separator and is then connected to the interface of the annular mixed gas box in the upper section of the once-through furnace through an insulation pipe. The lower part of the gravity separator is an inverted frustum-shaped container with a plate heat exchanger installed inside. The air interface of the plate heat exchanger is connected to a high-pressure blower, and the outlet is connected to a high-pressure air interface that is connected to the heat exchange chamber shell through a hot air pipe. The gaps of the plate heat exchanger are filled with hot solid slag particles that move from top to bottom.

8. The low-carbon and energy-saving ore reduction method according to claim 1, characterized in that, The high-frequency molten iron condenser includes a frame, a drive mechanism supporting and driving the frame to rotate intermittently, multiple sets of spring steel plates, a platform, a precision rod-making mold, an annular pouring cup, a bottom valve, a high-frequency vibrator, and a molten iron cleaning machine. The outer edge of the frame is circumferentially connected to the platform via multiple sets of spring steel plates. An annular base plate is provided at the bottom of the platform, and an annular panel is provided at the top. A cylindrical connecting plate is provided between the annular panel and the annular base plate. One side of the cylindrical connecting plate is connected to the spring steel plate via an inner flange plate, and the other side is provided with a rod-making mold mounting position. The inner flange plate has spring assembly fixing holes. The annular base plate has rod-making demolding holes, tie rod screw holes, and bottom valve seat positioning screw holes. The cylindrical connecting plate… Cooling water pipe through holes are provided at the top and bottom of the connecting plate; several precision rod molds are set on the frame, and the bottom plane of the precision rod mold is installed on the upper plane of the annular base plate. The height from the upper plane of the annular base plate to the annular panel is equal to the height of the rod mold; the bottom plane of the annular pouring cup, which is fixed to the annular panel, is pressed against the upper plane of the precision rod mold by bolts and tie rods; the bottom of the annular pouring cup has a through hole consistent with the mold position. The annular pouring cup holds the liquid alloy poured from the molten iron ladle and injects the liquid alloy into the precision rod mold through the through hole. A rod demolding hole is opened at the corresponding position of the annular base plate at the bottom of the precision rod mold. The rod demolding hole is coaxial with the rod mold and its diameter is larger than the maximum diameter of the rod. The bottom valve includes a valve seat, a locating pin for the valve seat, a pressure spring for the valve seat, a valve core, a valve core lever, a roller, and a guide rail. The bottom valve is installed directly below the annular base plate corresponding to the mold position. The valve seat is provided with a locating hole, a valve core hole, and a lever groove. The locating pin passes through the locating hole of the valve seat and is then screwed vertically into the locating screw hole from the bottom plane of the annular base plate. The valve seat is in close contact with the bottom plane of the annular base plate by the elastic force of the pressure spring. The valve core is provided inside the valve seat, and a valve core lever is provided on the valve core. The pressure spring is vertically... The spring is positioned between the lower plane of the valve seat and the upper plane of the guide rail. The upper plane of the spring presses against the bottom plane of the valve seat, and the lower plane of the spring presses against the upper plane of the guide rail. The guide rail is positioned below the spring and fixed to the base plane of the guide rail. The guide rail is an annular flat plate with a gradually outward displacement. A closed-loop guide rail groove is provided on the upper surface of the annular flat plate. The guide rail groove smoothly moves outward at the point of gradual outward displacement. All rollers connected to the valve core lever are located within the guide rail groove. Several high-frequency vibrators are installed on the test stand, with a vibration frequency of 50-10000Hz. The molten iron cleaning machine includes a support frame that is independently fixed outside the outer circumference of the test stand. The cleaning blade of the molten iron cleaning machine extends into the annular pouring cup, and the bottom plane and side plane of the blade are respectively clearance-fitted with the bottom plane and side plane of the pouring cup. The drive mechanism drives the frame to rotate intermittently, and the frame then drives the test stand to rotate periodically in a "stop-rotate-stop" cycle through spring steel plates. The rotation period is 0.5-5 seconds, of which the stopping time accounts for 70%-85% of the cycle time and the rotation time accounts for 15%-30% of the cycle time.

9. The low-carbon and energy-saving ore reduction method according to claim 1, characterized in that, Between several mold positions before and after the demolding station, the guide rail groove deviates from the axis of the precision rod mold in a smoothly changing curve, causing the roller to drive the valve core lever to move, so that the valve core is in a state of gradual opening or gradual closing. When it moves to the demolding station, the valve core is fully open. Outside the mold positions before and after the demolding station, the center line circle of the guide rail groove coincides with the plane projection circle of the axis of the precision rod mold, so that the valve core is in a static closed state.

10. A low-carbon and energy-saving ore reduction method according to claim 9, characterized in that, The precision rod-making mold includes an inner mold and an outer mold spaced apart, with a cooling water channel formed between the inner mold and the outer mold. The top of the precision rod-making mold is provided with a cooling water inlet pipe communicating with the cooling water channel, and the bottom is provided with a cooling water outlet pipe communicating with the cooling water channel. A sealing ring is provided between the tops of the inner mold and the outer mold.

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