Fluidized coal-based pre-reduced nickel laterite ore melting system and molten iron preparation method

Abstract

A fluidized coal-based pre-reduction subsystem and a method for preparing molten iron from laterite nickel ore are disclosed, belonging to the field of laterite nickel ore reduction roasting technology. The system includes a preheating oxidation system, a fluidized coal-based pre-reduction system, a high-temperature molten iron subsystem, and a hot air circulation system; wherein the preheating oxidation system, the fluidized coal-based pre-reduction system, and the high-temperature molten iron subsystem are connected sequentially, and the hot air circulation system connects all systems into a closed loop. The method for preparing nickel-containing molten iron using the above system includes the following steps: 1. Feeding and preheating oxidation operation; 2. Fluidized coal-based pre-reduction operation; 3. High-temperature molten iron subsystem operation. The method for preparing nickel-containing molten iron using the fluidized coal-based pre-reduction-molten iron subsystem has advantages such as no need for coke, low reducing agent consumption, large processing capacity, low power consumption, environmental friendliness, compact process, and high degree of automation.

Description

Technical Field

[0001] This invention belongs to the field of laterite nickel ore reduction roasting technology, specifically relating to a fluidized coal-based pre-reduced ore hot melting subsystem for laterite nickel ore and a method for preparing molten iron. Background Technology

[0002] Nickel is an important strategic metal, widely used in stainless steel, defense, aerospace, and transportation, primarily as a metallic material, in electroplating, and in non-alloy applications. Laterite nickel ore is the main source of nickel resources, but its complex mineralogical properties make physical methods unsuitable for producing high-grade nickel concentrate, necessitating metallurgical methods. The rotary kiln-electric furnace process is one of the most effective means of processing laterite nickel ore. The process flow is as follows: after crushing, the raw ore is first dried in a first-stage rotary kiln to remove most of the free water; then, in the low-temperature section (700℃~800℃) of the second-stage rotary kiln, crystal water is removed, followed by selective pre-reduction in the high-temperature section (920℃~1000℃) of the rotary kiln (with a carbon deficiency and 4%~6% coal blend); the pre-reduced roasted ore is then fed into an electric arc furnace where semi-coke is used as a reducing agent for final reduction, achieving slag-iron separation.

[0003] In production practice, some shortcomings and deficiencies have been found in the rotary kiln-electric furnace process. For example, during the pre-reduction of the mixture in the high-temperature section of the rotary kiln, ring formation occurs due to the softening and melting of the material. In production, the pre-reduction temperature is lowered (<1000℃) to avoid ring formation, but low temperatures are not conducive to carbon gasification, thus affecting the pre-reduction rate. Due to the low pre-reduction temperature, the reduction of nickel oxide in laterite nickel ore is inhibited, ultimately relying mainly on the molten reduction in the electric arc furnace to achieve the reduction of nickel and iron and the slag-iron separation, resulting in high energy consumption. The contact between the pulverized coal and the laterite nickel ore particles is insufficient, and the reduction effect needs to be improved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a fluidized coal-based pre-reduction and smelting system for laterite nickel ore. This system employs fluidized roasting technology to avoid the ring formation problem in rotary kilns while achieving close contact and efficient gas-solid reaction between laterite nickel ore and low-sulfur coal powder. The material is heated to 1000–1200°C through a preheating oxidation system, increasing the reduction rate of iron and nickel in the laterite nickel ore. The reduction of nickel and iron is accomplished jointly by the fluidized pre-reduction reactor (8) and the high-temperature smelting furnace (10). Through these systems, this invention achieves three-stage operations: preheating oxidation, fluidized coal-based pre-reduction, and high-temperature smelting of laterite nickel ore, realizing fluidized coal-based pre-reduction and smelting of laterite nickel ore to prepare qualified nickel-containing molten iron products.

[0005] A fluidized coal-based pre-reduction ore melting subsystem for laterite nickel ore includes a preheating oxidation system, a fluidized coal-based pre-reduction system, a high-temperature ore melting subsystem, and a hot air circulation system; wherein the preheating oxidation system, the fluidized coal-based pre-reduction system, and the high-temperature ore melting subsystem are connected sequentially, and the hot air circulation system connects the systems into a closed loop.

[0006] The preheating oxidation system includes a silo (1), a loss-in-weight scale (2), a primary cyclone separator (3), a primary sealing valve (4), a preheating oxidation reactor (5), and a secondary cyclone separator (6). The silo (1) is connected to the feed port of the primary cyclone separator (3) via the loss-in-weight scale (2). The primary cyclone separator (3), the primary sealing valve (4), the preheating oxidation reactor (5), and the secondary cyclone separator (6) are connected in sequence. An air inlet is provided at the lower part of the primary sealing valve (4).

[0007] The fluidized coal-based pre-reduction system includes a secondary sealing valve (7), a fluidized pre-reduction reactor (8), and a tertiary cyclone separator (11). The secondary sealing valve (7) and the fluidized pre-reduction reactor (8) are provided with nitrogen inlets at the bottom, and the tertiary cyclone separator (11) is provided with a feed inlet on the side. The inner wall of the fluidized pre-reduction reactor (8) is provided with heating wires. The secondary sealing valve (7) and the fluidized pre-reduction reactor (8) are connected, and a low-sulfur coal feed port is also provided at the connection. The feed port of the tertiary cyclone separator (11) is connected to the discharge port of the fluidized pre-reduction reactor (8), and the bottom ash outlet of the tertiary cyclone separator (11) is connected to the middle of the fluidized pre-reduction reactor (8).

[0008] The high-temperature ferroalloy melting subsystem includes a three-stage sealing valve (9) and a high-temperature ferroalloy melting sub-furnace (10); the three-stage sealing valve (9) is provided with a nitrogen inlet at the bottom, and the high-temperature ferroalloy melting sub-furnace (10) is provided with a nickel-containing molten iron outlet and a tailings outlet at the bottom; the three-stage sealing valve (9) and the high-temperature ferroalloy melting sub-furnace (10) are connected in sequence.

[0009] The hot air circulation system includes a dust collector (12), a fan (13), a hot air furnace (14), and a chimney (15). The dust collector (12), the fan (13), and the hot air furnace (14) are connected in sequence. The chimney (15) is located in the middle of the pipeline connecting the fan (13) and the hot air furnace (14). The hot air furnace (14) has a flue gas outlet at the top and a natural gas and air inlet on one side.

[0010] Furthermore, the dust collector (12) of the hot air circulation system is connected to the first-stage cyclone separator (3) of the preheating oxidation system; the hot air furnace (14) of the hot air circulation system is connected to the preheating oxidation reactor (5) of the preheating oxidation system, thus forming a closed-loop circulation of hot air. The main airflow circulation has an air inlet and an exhaust chimney (15) installed in the pipeline between the blower (13) and the hot air furnace (14).

[0011] The main gas flow direction in the system is: hot blast stove (14) → preheating oxidation reactor (5) → secondary cyclone separator (6) → primary cyclone separator (3) → dust collector (12) → fan (13) → hot blast stove (14).

[0012] Furthermore, the material flow in the system is as follows: silo (1) → loss-in-weight scale (2) → primary cyclone separator (3) → primary sealing valve (4) → preheating oxidation reactor (5) → secondary cyclone separator (6) → secondary sealing valve (7) → fluidized pre-reduction reactor (8) → tertiary sealing valve (9) → high-temperature ferroelectric melting furnace (10).

[0013] A method for preparing nickel-containing molten iron, using the aforementioned laterite nickel ore fluidized coal-based pre-reduced ore thermal melting subsystem, includes the following steps:

[0014] Step 1: Feeding and Preheating Oxidation Operation

[0015] Lateritic nickel ore with a nickel grade of 0.5-2.8%, an iron grade of 15-55%, a particle size of -2.5mm, and a moisture content of 10-40% is fed into the fluidized coal-based pre-reduction system at a rate of 60-110 kg / h. The lateritic nickel ore is fed from the silo (1) through the loss-in-weight weigher (2) into the inlet of the primary cyclone separator (3). Under the action of wind, the lateritic nickel ore and hot flue gas enter the primary cyclone separator (3) together and undergo gas-solid separation in the cyclone separator. The flue gas is discharged from the top outlet of the cyclone separator. The material enters the bottom inlet of the preheating oxidation reactor (5) through the primary airlock valve from the bottom outlet of the primary cyclone separator (3).

[0016] The function of the sealing valve is to ensure unidirectional flow of materials and to isolate gas flow.

[0017] Furthermore, laterite nickel ore is carried upwards from bottom to top in the preheating oxidation reactor (5) by hot flue gas to the secondary cyclone separator (6); the preheating and oxidation of the material are achieved in the preheating oxidation reactor (5) and the secondary cyclone separator (6); at this time, the material is gradually heated to 1000-1200°C by hot flue gas, and the heat from the combustion of air and natural gas in the hot blast stove (14) is transferred to the circulating hot flue gas through the internal heat exchanger and fed into the preheating oxidation reactor (5);

[0018] The hot flue gas is supplied by a hot blast stove (14), a fluidized bed pre-reduction reactor (8), and a high-temperature submerged arc furnace (10).

[0019] Step 2: Fluidized coal-based pre-reduction operation

[0020] After preheating and oxidation, the laterite nickel ore enters the fluidized bed pre-reduction reactor (8) through the lower outlet of the secondary cyclone separator (6) and the secondary sealing valve (7). Low-sulfur coal (20-80 kg / h) is used as the sole reducing agent and is fed into the fluidized bed pre-reduction reactor (8). The carbonaceous material in the coal burns, creating a CO reducing atmosphere inside the reactor. During the flow from the first chamber to the fourth chamber, the hematite in the laterite nickel ore is gradually reduced to magnetite. Simultaneously, the material is heated to 22-38 m³ / h. 3 Under the action of nitrogen gas, the material moves in a fluidized state within the four chambers. The inner wall of the fluidized pre-reduction reactor (8) is equipped with heating wires to ensure that the internal material temperature is 1000-1200℃.

[0021] It should be noted that in the gas circulation of the fluidized bed pre-reduction reactor (8), nitrogen is fed into the lower part of the fluidized bed pre-reduction reactor (8) and discharged from the discharge port. The flue gas at the discharge port of the fluidized bed pre-reduction reactor (8) is mainly composed of nitrogen. The CO produced by the low-sulfur coal has been completely consumed. The flue gas, mixed with fine particles, enters the three-stage cyclone separator (11), where gas-solid separation is achieved. The flue gas is discharged from the upper part of the three-stage cyclone separator (11) into the preheating oxidation reactor (5).

[0022] Step 3: High-temperature ore smelting operation

[0023] The high-temperature laterite nickel ore, after fluidization pre-reduction, enters the high-temperature ferroalloy smelting furnace (10) through a three-stage sealing valve (9). The furnace temperature is controlled at 1300–1500℃. At this time, the nickel in the original ore is reduced to metallic nickel, and the magnetite is deeply reduced to metallic iron. Because nickel mainly exists in iron minerals in an isomorphous form, the final product is nickel-iron molten iron.

[0024] In the nickel-containing molten iron, the nickel recovery rate is ≥85% and the iron recovery rate is ≥85%.

[0025] The key features of the fluidized coal-based pre-reduced ore thermal melting subsystem for laterite nickel ore provided by this invention are:

[0026] 1. This invention employs fluidized bed roasting technology. During the roasting process, it is necessary to ensure that the gas supply to the reactor and sealing valve is appropriate to ensure that the material is in a fluidized state.

[0027] 2. The sealing valve should prevent gas leakage and completely isolate the oxygen atmosphere in the preheating oxidation system to ensure that the fluidized pre-reduction reactor (8) is an oxygen-free reduction environment.

[0028] 3. The low-sulfur coal content in the fluidized bed pre-reduction reactor (8) should be appropriate. On the one hand, it is necessary to ensure that the CO generated by combustion can fully reduce the hematite, and on the other hand, excessive CO should not be generated to avoid the exhaust gas from the fluidized bed pre-reduction reactor (8) entering the preheating oxidation reactor (5) and affecting the oxidation effect.

[0029] The present invention discloses a fluidized coal-based pre-reduced ore hot melting subsystem for laterite nickel ore and a method for preparing molten iron. Compared with traditional technologies, its advantages and innovations are as follows:

[0030] 1. No coke required and low reducing agent consumption: Low-sulfur coal can be used as a reducing agent, without the use of coke or semi-coke. Furthermore, the fluidized bed heating effect is high, the gas-solid reaction is complete, the reduction efficiency is high, and the coal consumption is more than 20% lower than that of a rotary kiln.

[0031] 2. High processing capacity: In the deep reduction roasting process, the pre-reduction feed has a high ferrous oxide content and a high material temperature, which effectively reduces the heating time and reduction reaction time of the material in the electric arc furnace, greatly improving the reaction efficiency. The processing capacity of the electric furnace of the same power is 50-100% higher than that of the RKEF process.

[0032] 3. Low power consumption: 20-50% lower than the rotary kiln-electric furnace process;

[0033] 4. Environmentally friendly: The fluidized bed roasting system of this process has its own denitrification and dust removal devices, eliminating the need for new waste gas treatment devices and achieving ultra-low emissions.

[0034] 5. Compact process: The process is in a closed state, with a compact flow, and the entire process achieves continuous heat delivery of materials.

[0035] 6. High degree of automation: This process has a high degree of automation and can be remotely controlled, reducing the number of operators by 30-50% compared to the rotary kiln-electric furnace process. Attached Figure Description

[0036] Figure 1 A schematic diagram of the structure of a thermal melting subsystem for fluidized coal-based pre-reduced laterite nickel ore;

[0037] In the diagram, 1 is the silo, 2 is the loss-in-weight scale, 3 is the primary cyclone separator, 4 is the primary sealing valve, 5 is the preheating oxidation reactor, 6 is the secondary cyclone separator, 7 is the secondary sealing valve, 8 is the fluidized bed pre-reduction reactor, 9 is the tertiary sealing valve, 10 is the high-temperature submerged arc furnace, 11 is the tertiary cyclone separator, 12 is the dust collector, 13 is the blower, 14 is the hot blast stove, and 15 is the chimney. Detailed Implementation

[0038] Combined with appendix Figure 1This invention provides a clear and complete description of the technical solutions implemented in this patent. It should be noted that the examples described in this invention are for further explanation and illustration only, and not for limiting its scope of application. All other embodiments obtained by those skilled in the art based on this invention without inventive effort are within the protection scope of this patent.

[0039] Example 1

[0040] A fluidized coal-based pre-reduced ore thermal melting subsystem for lateritic nickel ore, such as Figure 1 As shown, it mainly includes a preheating oxidation system, a fluidized coal-based pre-reduction system, a high-temperature ferroalloy melting subsystem, and a hot air circulation system. The preheating oxidation system, the fluidized coal-based pre-reduction system, and the high-temperature ferroalloy melting subsystem are connected sequentially, and the hot air circulation system connects the various systems into a closed loop.

[0041] The preheating oxidation system includes a silo (1), a loss-in-weight scale (2), a primary cyclone separator (3), a primary sealing valve (4), a preheating oxidation reactor (5), and a secondary cyclone separator (6). The silo (1) is connected to the feed port of the primary cyclone separator (3) via the loss-in-weight scale (2). The primary cyclone separator (3), the primary sealing valve (4), the preheating oxidation reactor (5), and the secondary cyclone separator (6) are connected in sequence. An air inlet is provided at the bottom of the primary sealing valve (4).

[0042] The fluidized coal-based pre-reduction system includes a secondary sealing valve (7), a fluidized pre-reduction reactor (8), and a tertiary cyclone separator (11). The secondary sealing valve (7) and the fluidized pre-reduction reactor (8) are provided with nitrogen inlets at the bottom, and the tertiary cyclone separator (11) is provided with a feed inlet on the side. The inner wall of the fluidized pre-reduction reactor (8) is provided with heating wires. The secondary sealing valve (7) and the fluidized pre-reduction reactor (8) are connected, and a low-sulfur coal feed port is also provided at the connection. The feed port of the tertiary cyclone separator (11) is connected to the discharge port of the fluidized pre-reduction reactor (8), and the bottom ash outlet of the tertiary cyclone separator (11) is connected to the middle of the fluidized pre-reduction reactor (8).

[0043] The high-temperature ferroalloy melting subsystem includes a three-stage sealing valve (9) and a high-temperature ferroalloy melting sub-furnace (10); the three-stage sealing valve (9) is provided with a nitrogen inlet at the bottom, and the high-temperature ferroalloy melting sub-furnace (10) is provided with a nickel-containing molten iron outlet and a tailings outlet at the bottom; the three-stage sealing valve (9) and the high-temperature ferroalloy melting sub-furnace (10) are connected in sequence.

[0044] The hot air circulation system includes a dust collector (12), a fan (13), a hot air furnace (14), and a chimney (15). The dust collector (12), the fan (13), and the hot air furnace (14) are connected in sequence. The chimney (15) is located in the middle of the pipeline connecting the fan (13) and the hot air furnace (14). The hot air furnace (14) has a flue gas outlet at the top and a natural gas and air inlet on one side.

[0045] The dust collector (12) of the hot air circulation system is connected to the primary cyclone separator (3) of the preheating oxidation system; the hot air furnace (14) of the hot air circulation system is connected to the preheating oxidation reactor (5) of the preheating oxidation system, thus forming a closed-loop circulation of hot air. In this embodiment, the main gas flow direction is: hot air furnace (14) → preheating oxidation reactor (5) → secondary cyclone separator (6) → primary cyclone separator (3) → dust collector (12) → fan (13) → hot air furnace (14). In addition, an air inlet and a chimney (15) for exhaust are provided in the pipeline between the fan (13) and the hot air furnace (14) of the main airflow circulation.

[0046] The material flow path in this embodiment is as follows: silo (1) → loss-in-weight scale (2) → primary cyclone separator (3) → primary sealing valve (4) → preheating oxidation reactor (5) → secondary cyclone separator (6) → secondary sealing valve (7) → fluidized bed pre-reduction reactor (8) → tertiary sealing valve (9) → high-temperature ferroalloy melting furnace (10).

[0047] A method for preparing nickel-containing molten iron from a laterite nickel ore in Indonesia using fluidized bed coal-based pre-reduction ore thermal fusion:

[0048] Step 1, Feeding and Preheating Oxidation: Lateritic nickel ore with a Ni content of 1.34%, a TFe content of 43.49%, a particle size of -2.5 mm, and a moisture content of 10% is fed into the fluidized coal-based pre-reduction system at a rate of 60 kg / h. The lateritic nickel ore is fed from the silo (1) through the loss-in-weight weigher (2) into the inlet of the primary cyclone separator (3). Under the action of wind, the lateritic nickel ore and hot flue gas enter the primary cyclone separator (3) together and undergo gas-solid separation in the cyclone separator. The flue gas is discharged from the top outlet of the cyclone separator. The material enters the bottom inlet of the preheating oxidation reactor (5) through the primary airlock valve from the bottom outlet of the primary cyclone separator (3).

[0049] Furthermore, the laterite nickel ore is carried upwards by the hot flue gas in the preheating oxidation reactor (5) to the secondary cyclone separator (6). The preheating and oxidation of the material are achieved in the preheating oxidation reactor (5) and the secondary cyclone separator (6). At this time, the material is gradually heated to 1000°C by the hot flue gas.

[0050] Step 2, Fluidized Coal-Based Pre-Reduction Operation: After preheating and oxidation, the laterite nickel ore enters the fluidized pre-reduction reactor (8) through the lower outlet of the secondary cyclone separator (6) and the secondary sealing valve (7). 20 kg / h of low-sulfur coal is fed into the fluidized pre-reduction reactor (8) as the sole reducing agent, and the carbonaceous material in it burns to form a CO reducing atmosphere inside the reactor. Therefore, the hematite in the laterite nickel ore is gradually reduced to magnetite as it flows from the first chamber to the fourth chamber. Simultaneously, the material is at 25 m... 3 Under the action of nitrogen gas, the material moves in a fluidized state within the four chambers of the W-shaped structure. The inner wall of the fluidized pre-reduction reactor (8) is equipped with heating wires to ensure that the internal material temperature is 1000℃.

[0051] Step 3, High-Temperature Sub-Metal Melting Operation: The high-temperature laterite nickel ore, after fluidization pre-reduction, enters the high-temperature sub-metallic smelting furnace (10) through a three-stage sealing valve (9). The furnace temperature is controlled at 1300℃. At this time, the nickel in the original ore is reduced to metallic nickel, and the magnetite is deeply reduced to metallic iron. Because nickel mainly exists in iron minerals in an isomorphous form, the final product is nickel-iron molten iron. The nickel recovery rate in the nickel-iron molten iron is 85.28%, and the iron recovery rate is 87.85%.

[0052] Example 2

[0053] Using a laterite nickel ore from Sichuan as raw material, a method for preparing nickel-containing molten iron from fluidized coal-based pre-reduced ore using the system described in Example 1 is as follows:

[0054] Step 1, Feeding and Preheating Oxidation: Lateritic nickel ore with a Ni content of 1.26%, a TFe content of 36.51%, a particle size of -2mm, and a moisture content of 25% is fed into the fluidized coal-based pre-reduction system at a rate of 80kg / h. The lateritic nickel ore is fed from the silo (1) through the loss-in-weight weigher (2) into the inlet of the primary cyclone separator (3). Under the action of wind, the lateritic nickel ore and hot flue gas enter the primary cyclone separator (3) together and undergo gas-solid separation in the cyclone separator. The flue gas is discharged from the top outlet of the cyclone separator. The material enters the bottom inlet of the preheating oxidation reactor (5) through the primary airlock valve from the bottom outlet of the primary cyclone separator (3).

[0055] Furthermore, the laterite nickel ore is carried upwards by the hot flue gas in the preheating oxidation reactor (5) to the secondary cyclone separator (6). The preheating and oxidation of the material are achieved in the preheating oxidation reactor (5) and the secondary cyclone separator (6). At this time, the material is gradually heated to 1100°C by the hot flue gas.

[0056] Step 2, Fluidized Coal-Based Pre-Reduction Operation: After preheating and oxidation, the laterite nickel ore enters the fluidized pre-reduction reactor (8) through the lower outlet of the secondary cyclone separator (6) and the secondary sealing valve (7). 30 kg / h of low-sulfur coal is fed into the fluidized pre-reduction reactor (8) as the sole reducing agent, and the carbonaceous material in it burns to form a CO reducing atmosphere inside the reactor. Therefore, the hematite in the laterite nickel ore is gradually reduced to magnetite as it flows from the first chamber to the fourth chamber. Simultaneously, the material at 34 m... 3 Under the action of nitrogen gas, the material moves in a fluidized state within the four chambers of the W-shaped structure. The inner wall of the fluidized pre-reduction reactor (8) is equipped with heating wires to ensure that the internal material temperature is 1100℃.

[0057] Step 3, High-Temperature Sub-Metal Melting Operation: The high-temperature laterite nickel ore, after fluidization pre-reduction, enters the high-temperature sub-metallic smelting furnace (10) through a three-stage sealing valve (9). The furnace temperature is controlled at 1400℃. At this time, the nickel in the original ore is reduced to metallic nickel, and the magnetite is deeply reduced to metallic iron. Because nickel mainly exists in iron minerals in an isomorphous form, the final product is nickel-iron molten iron. The nickel recovery rate in the nickel-iron molten iron is 98.27%, and the iron recovery rate is 95.24%.

[0058] Example 3

[0059] Using a laterite nickel ore from Indonesia as raw material, a method for preparing nickel-containing molten iron from fluidized coal-based pre-reduced ore using the system described in Example 1 is as follows:

[0060] Step 1, Feeding and Preheating Oxidation: Lateritic nickel ore with a Ni content of 1.34%, a TFe content of 43.49%, a particle size of -1.5 mm, and a moisture content of 40% is fed into the fluidized coal-based pre-reduction system at a rate of 110 kg / h. The lateritic nickel ore is fed from the silo (1) through the loss-in-weight weigher (2) into the inlet of the primary cyclone separator (3). Under the action of wind, the lateritic nickel ore and hot flue gas enter the primary cyclone separator (3) together and undergo gas-solid separation in the cyclone separator. The flue gas is discharged from the top outlet of the cyclone separator. The material enters the bottom inlet of the preheating oxidation reactor (5) through the primary airlock valve from the bottom outlet of the primary cyclone separator (3).

[0061] Furthermore, the laterite nickel ore is carried upwards by the hot flue gas in the preheating oxidation reactor (5) to the secondary cyclone separator (6). The preheating and oxidation of the material are achieved in the preheating oxidation reactor (5) and the secondary cyclone separator (6). At this time, the material is gradually heated to 1000°C by the hot flue gas.

[0062] Step 2, Fluidized Coal-Based Pre-Reduction Operation: After preheating and oxidation, the laterite nickel ore enters the fluidized pre-reduction reactor (8) through the lower outlet of the secondary cyclone separator (6) and the secondary sealing valve (7). 50 kg / h of low-sulfur coal is fed into the fluidized pre-reduction reactor (8) as the sole reducing agent, and the carbonaceous combustion within it creates a CO reducing atmosphere inside the reactor. Therefore, the hematite in the laterite nickel ore is gradually reduced to magnetite as it flows from the first chamber to the fourth chamber. Simultaneously, the material at 35 m... 3 Under the action of nitrogen gas, the material moves in a fluidized state within the four chambers of the W-shaped structure. The inner wall of the fluidized pre-reduction reactor (8) is equipped with heating wires to ensure that the internal material temperature is 1100℃.

[0063] Step 3, High-Temperature Sub-Metal Melting Operation: The high-temperature laterite nickel ore, after fluidized bed pre-reduction, enters the high-temperature sub-metallic smelting furnace (10) through a three-stage sealing valve (9). The furnace temperature is controlled at 1500℃. At this point, the nickel in the original ore is reduced to metallic nickel, and the magnetite is deeply reduced to metallic iron. Because nickel mainly exists in iron minerals in an isomorphous form, the final product is nickel-iron molten iron. The nickel recovery rate in the nickel-iron molten iron is 98.84%, and the iron recovery rate is 98.54%.

[0064] Example 4

[0065] Using a laterite nickel ore from Indonesia as raw material, a method for preparing nickel-containing molten iron from fluidized coal-based pre-reduced ore using the system described in Example 1 is as follows:

[0066] Step 1, Feeding and Preheating Oxidation Operation:

[0067] Lateritic nickel ore with a Ni content of 1.34%, a TFe content of 43.49%, a particle size of -1.5 mm, and a moisture content of 15% is fed into the fluidized coal-based pre-reduction system at a rate of 100 kg / h. The lateritic nickel ore is fed from the silo (1) through the loss-in-weight weigher (2) into the inlet of the primary cyclone separator (3). Under the action of wind, the lateritic nickel ore and hot flue gas enter the primary cyclone separator (3) together and undergo gas-solid separation within the cyclone separator. The flue gas is discharged from the top outlet of the cyclone separator. The material enters the bottom inlet of the preheating oxidation reactor (5) through the primary airlock valve from the bottom outlet of the primary cyclone separator (3).

[0068] Furthermore, the laterite nickel ore is carried upwards by the hot flue gas in the preheating oxidation reactor (5) to the secondary cyclone separator (6). The preheating and oxidation of the material are achieved in the preheating oxidation reactor (5) and the secondary cyclone separator (6). At this time, the material is gradually heated to 1000°C by the hot flue gas.

[0069] Step 2, Fluidized coal-based pre-reduction operation:

[0070] After preheating and oxidation, the laterite nickel ore enters the fluidized bed pre-reduction reactor (8) through the lower outlet of the secondary cyclone separator (6) and the secondary sealing valve (7). 50 kg / h of low-sulfur coal is fed into the fluidized bed pre-reduction reactor (8) as the sole reducing agent, and the carbonaceous combustion within it creates a CO reducing atmosphere inside the reactor. The hematite in the laterite nickel ore is gradually reduced to magnetite as it flows from the first chamber to the fourth chamber. Simultaneously, the material is subjected to a 30m... 3 Under the action of nitrogen gas, the material moves in a fluidized state within the four chambers of the W-shaped structure. The inner wall of the fluidized pre-reduction reactor (8) is equipped with heating wires to ensure that the internal material temperature is 1200℃.

[0071] Step 3, High-Temperature Mineral Thermal Melting Operation:

[0072] The high-temperature lateritic nickel ore, after fluidization pre-reduction, enters the high-temperature ferroalloy smelting furnace (10) through a three-stage sealing valve (9). The furnace temperature is controlled at 1450℃. At this point, the nickel in the ore is reduced to metallic nickel, and the magnetite is further reduced to metallic iron. Because nickel mainly exists in iron minerals in an isomorphous form, the final product is nickel-iron molten iron. The nickel recovery rate in the nickel-iron molten iron is 96.54%, and the iron recovery rate is 97.98%.

[0073] Example 5

[0074] Similar to Example 3, except that the low-sulfur coal feed rate is reduced to 25 kg / h. Nickel-containing molten iron can still be produced at this time, with the nickel recovery rate reduced to 92.58% and the iron recovery rate to 93.32%.

[0075] Example 6

[0076] Similar to Example 1, except that the low-sulfur coal feed rate is 70 kg / h. The resulting nickel-containing molten iron product has a nickel recovery rate of 96.34% and an iron recovery rate of 96.15%.

[0077] Example 7

[0078] Similar to Example 2, except that the low-sulfur coal feed rate is reduced to 20 kg / h. Nickel-containing molten iron can still be produced at this time, with the nickel recovery rate reduced to 94.26% and the iron recovery rate to 93.70%.

[0079] Comparative Example 1

[0080] Similar to Example 2, the difference is that preheating oxidation roasting is not performed in this example; the material is directly fed into the fluidized bed pre-reduction reactor (8). Although nickel-containing ferrous metals can still be produced, the nickel recovery rate is only 85.21%, and the iron recovery rate is only 85.95%. Compared with Example 2, the power consumption in this example increases by 40%. This is because the limonite in the raw ore is not pre-oxidized to hematite, and the ferrous reduction degree of the product from direct reduction roasting of limonite is low. In addition, the room temperature material is not preheated and needs to be heated by the fluidized bed pre-reduction reactor (8) and the ferroalloy melting furnace, resulting in a significant increase in overall power consumption.

[0081] Comparative Example 2

[0082] Similar to Example 3, the difference is that preheating oxidation roasting is not performed in this example; the material is directly fed into the fluidized bed pre-reduction reactor (8). Although nickel-containing molten iron can still be produced, the nickel recovery rate is only 86.45%, and the iron recovery rate is only 87.38%. Compared with Example 3, the power consumption in this example increases by 50%. This is because the limonite in the raw ore is not pre-oxidized to hematite, and the ferrous reduction degree of the product from direct reduction roasting of limonite is low. In addition, the room temperature material is not preheated and needs to be heated by the fluidized bed pre-reduction reactor (8) and the ferroalloy melting furnace, resulting in a significant increase in overall power consumption.

[0083] Comparative Example 3

[0084] Similar to Example 2, but without fluidized coal-based pre-reduction roasting; the preheated oxidation product is directly fed into the ore-smelting furnace. Although nickel-containing molten iron is ultimately produced, the nickel recovery rate is only 85.34%, and the iron recovery rate is only 82.23%. Compared to Example 2, the power consumption in this example increases by 28%.

Claims

1. A fluidized bed coal-based pre-reduction ore thermal melting subsystem for laterite nickel ore, characterized in that, It includes a preheating oxidation system, a fluidized coal-based pre-reduction system, a high-temperature smelting subsystem, and a hot air circulation system; wherein, the preheating oxidation system, the fluidized coal-based pre-reduction system, and the high-temperature smelting subsystem are connected in sequence, and the hot air circulation system connects each system into a closed loop; The preheating oxidation system includes a silo (1), a loss-in-weight scale (2), a primary cyclone separator (3), a primary sealing valve (4), a preheating oxidation reactor (5), and a secondary cyclone separator (6); the silo (1) is connected to the feed port of the primary cyclone separator (3) through the loss-in-weight scale (2), and the primary cyclone separator (3), the primary sealing valve (4), the preheating oxidation reactor (5), and the secondary cyclone separator (6) are connected in sequence, and an air inlet is provided at the bottom of the primary sealing valve (4); The fluidized coal-based pre-reduction system includes a secondary sealing valve (7), a fluidized pre-reduction reactor (8), and a tertiary cyclone separator (11); the secondary sealing valve (7) and the fluidized pre-reduction reactor (8) are provided with nitrogen inlets at the bottom, the tertiary cyclone separator (11) is provided with a feed inlet on the side, and the inner wall of the fluidized pre-reduction reactor (8) is provided with heating wires; the secondary sealing valve (7) and the fluidized pre-reduction reactor (8) are connected, and a low-sulfur coal feed port is also provided at the connection point; the feed port of the tertiary cyclone separator (11) is connected to the discharge port of the fluidized pre-reduction reactor (8), and the bottom ash outlet of the tertiary cyclone separator (11) is connected to the middle of the fluidized pre-reduction reactor (8); The high-temperature molten metal melting subsystem includes a three-stage sealing valve (9) and a high-temperature molten metal melting sub-furnace (10); the three-stage sealing valve (9) is provided with a nitrogen inlet at the bottom, and the high-temperature molten metal melting sub-furnace (10) is provided with a nickel-containing molten iron outlet and a tailings outlet at the bottom; the three-stage sealing valve (9) and the high-temperature molten metal melting sub-furnace (10) are connected in sequence. The primary sealing valve (4), secondary sealing valve (7), and tertiary sealing valve (9) are designed to ensure unidirectional material flow and isolate gas flow. The fluidized pre-reduction reactor (8) has heating wires on its inner wall and a W-shaped four-chamber structure inside; The hot air circulation system includes a dust collector (12), a fan (13), a hot air furnace (14), and a chimney (15); the dust collector (12), the fan (13), and the hot air furnace (14) are connected in sequence, the chimney (15) is located in the middle of the pipeline connecting the fan (13) and the hot air furnace (14), the hot air furnace (14) is provided with a flue gas outlet at the top and a natural gas and air inlet on one side; The dust collector (12) of the hot air circulation system is connected to the first-stage cyclone separator (3) of the preheating oxidation system; the hot air furnace (14) of the hot air circulation system is connected to the preheating oxidation reactor (5) of the preheating oxidation system to form a closed-loop circulation of hot air. An air inlet and a chimney (15) for exhaust are provided in the pipeline between the blower (13) and the hot air furnace (14). The main gas flow direction in the system is: hot blast stove (14) → preheating oxidation reactor (5) → secondary cyclone separator (6) → primary cyclone separator (3) → dust collector (12) → fan (13) → hot blast stove (14); The flue gas outlets of the three-stage cyclone separator (11) and the high-temperature smelting furnace (10) are both connected to the bottom of the preheating oxidation reactor (5).

2. The fluidized coal-based pre-reduction ore thermal melting subsystem for laterite nickel ore according to claim 1, characterized in that, The material flow in the system is as follows: silo (1) → loss-in-weight scale (2) → primary cyclone separator (3) → primary sealing valve (4) → preheating oxidation reactor (5) → secondary cyclone separator (6) → secondary sealing valve (7) → fluidized bed pre-reduction reactor (8) → tertiary sealing valve (9) → high temperature ferroelectric melting furnace (10).

3. A method for preparing nickel-containing molten iron, implemented using the laterite nickel ore fluidized coal-based pre-reduction ore thermal melting subsystem described in claim 1, characterized in that... Includes the following steps: Step 1: Feeding and Preheating Oxidation Operation Lateritic nickel ore with a nickel grade of 0.5-2.8%, an iron grade of 15-55%, a particle size of -2.5mm, and a moisture content of 10-40% is fed into the fluidized coal-based pre-reduced ore hot melting subsystem at a rate of 60-110 kg / h. The lateritic nickel ore is fed from the silo (1) through the loss-in-weight scale (2) into the feed inlet of the first-stage cyclone separator (3). Under the action of wind, the lateritic nickel ore and hot flue gas enter the first-stage cyclone separator (3) together and undergo gas-solid separation in the cyclone separator. The flue gas is discharged from the top outlet of the cyclone separator. The material enters the bottom inlet of the preheating oxidation reactor (5) through the bottom outlet of the primary cyclone separator (3) and the primary sealing valve (4); Laterite nickel ore is fed from bottom to top into the secondary cyclone separator (6) in the preheating oxidation reactor (5) along with the hot flue gas; the preheating and oxidation of the material are achieved in the preheating oxidation reactor (5) and the secondary cyclone separator (6); the material is gradually heated to 1000~1200 ℃ by the hot flue gas; the heat from the combustion of air and natural gas in the hot blast stove (14) is transferred to the circulating hot flue gas through the internal heat exchanger and fed into the preheating oxidation reactor (5); The hot flue gas is supplied by a hot blast stove (14), a fluidized bed pre-reduction reactor (8), and a high-temperature submerged arc furnace (10); Step 2: Fluidized coal-based pre-reduction operation After preheating and oxidation, the laterite nickel ore enters the fluidized bed pre-reduction reactor (8) through the lower outlet of the secondary cyclone separator (6) and the secondary sealing valve (7); 20~80 kg / h of low-sulfur coal is used as the only reducing agent and is fed into the fluidized bed pre-reduction reactor (8) through the feed port. Carbon combustion forms a CO reducing atmosphere inside the fluidized bed pre-reduction reactor (8); The hematite in the laterite nickel ore is gradually reduced to magnetite as it flows from the first chamber to the fourth chamber; simultaneously, the material is at a depth of 22-38 m. 3 Under the action of nitrogen gas, the material moves in a fluidized state in the four chambers; the inner wall of the fluidized pre-reduction reactor (8) is equipped with heating wires to ensure that the internal material temperature is 1000~1200 ℃; In the gas circulation of the fluidized pre-reduction reactor (8), nitrogen is fed in from the bottom of the fluidized pre-reduction reactor (8) and discharged from the discharge port; the flue gas mixed with fine particles enters the three-stage cyclone separator (11), where gas-solid separation is achieved; the flue gas is discharged from the top of the three-stage cyclone separator (11) to the preheating oxidation reactor (5); Step 3: High-temperature ore smelting operation The high-temperature laterite nickel ore, after fluidization pre-reduction, enters the high-temperature smelting furnace (10) through a three-stage sealing valve (9); the temperature of the smelting furnace is controlled at 1300~1500 ℃; the nickel in the raw ore is reduced to metallic nickel, and the magnetite is reduced to metallic iron; the nickel element mainly exists in the iron mineral in the form of isomorphism, and nickel iron is produced in the form of nickel-containing molten iron; The recovery rate of nickel in nickel-containing iron molten metal is ≥85%, and the recovery rate of iron is ≥85%.

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