Feeding device of system for continuously distilling and purifying crude indium and using method of feeding device

Abstract

The invention relates to a feeding device of a system for continuously distilling and purifying crude indium and a using method of the feeding device, and aims to solve the problems of low efficiency, oxidation film pollution and impurity accumulation of traditional batch distillation. The device comprises a distillation furnace, a raw material furnace and a material conveying pipe, seamless connection between normal pressure of the raw material furnace and vacuum of the distillation furnace is realized through a pressure difference self-driven feeding structure, and shutdown cooling is avoided. The bottom of the raw material furnace is provided with a suction groove, the top is additionally provided with a filter ring to intercept an oxide film in real time, micro-positive pressure protection is formed in cooperation with nitrogen purging, and non-metal impurities such as O and C are reduced. The double-circulation parallel mode enables the melting time of the raw material furnace and the working time of the distillation furnace to be overlapped, and the single-batch interval time is shortened. The design of conveying pipe heating and kettle body heat preservation reduces energy consumption, and a circulating water system is optimized to prolong the service life of the crucible. According to the method, the whole process of distillation-feeding-pretreatment is continuous, the finished indium product is high in purity, the equipment utilization rate is increased, and the method is suitable for the production field of high-purity indium such as semiconductors and ITO target materials.

Description

Technical Field

[0001] The invention relates to the technical field of crude indium purification by distillation, and in particular to a feeding device of a continuous distillation crude indium purification system and a use method thereof. Background Art

[0002] At present, industrial purification of crude indium (purity 97%-99.7%) mainly adopts batch vacuum distillation method, and its core defects are as follows:

[0003] Intermittent operation is inefficient: each batch of distillation needs to go through the process of "heating up - distillation - cooling - opening the lid to clean impurities - filling". A single cycle takes 6-8 hours, of which 2.5-3 hours is required to cool to a safe temperature (<150°C), and the equipment utilization rate is insufficient.

[0004] Severe oxide film pollution: The traditional feeding method requires opening the lid, and the indium liquid is exposed to the air to form an oxide film, which enters the distillation furnace with the next batch of raw materials, resulting in a high content of non-metallic impurities in the finished indium, making it difficult to meet the 6N grade (99.9999%) high-purity indium requirements.

[0005] Vicious cycle of impurity accumulation: distillation residue (containing high-boiling point impurities such as Fe and Cu) adheres to the furnace wall and needs to be cleaned manually and mechanically. The residual rate is >5%, resulting in an increase in the impurity concentration gradient of subsequent batches and an increase in the total impurity content.

[0006] Limitations of existing technology improvement attempts:

[0007] Although some semi-continuous feeding designs (such as double furnace alternation) shorten the cooling time, they do not solve the problems of oxide film contamination and impurity accumulation, and the complexity of the equipment is greatly increased.

[0008] Traditional filtration devices rely on manual replacement of filters after shutdown, cannot adapt to continuous production needs, and have limited filtration efficiency. Summary of the invention

[0009] The present invention aims to overcome the above-mentioned shortcomings of the prior art and provides a feeding device for a continuous distillation and purification system of crude indium and a method for using the same.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A feeding device for a continuous distillation and purification system of crude indium, comprising: a distillation furnace, a raw material furnace and a feeding pipe, wherein one end of the feeding pipe is arranged at the bottom of the raw material furnace, and the other end is arranged in the distillation furnace, and a feeding valve is arranged in the middle of the feeding pipe;

[0012] The raw material furnace comprises a raw material crucible, a kettle body and a kettle cover. The kettle body is sleeved on the outside of the raw material crucible. The kettle cover is provided with a vacuum pipeline and a nitrogen pipeline. The kettle body is provided with a circulating water cooling system and a constant temperature heating system.

[0013] Furthermore, the circulating water cooling system is connected to the kettle cover, and the circulating water inlet and outlet are arranged on the kettle cover.

[0014] Furthermore, a suction trough is provided at the bottom of the raw material crucible, and the end of the feed pipe is arranged in the suction trough.

[0015] Furthermore, a filter ring for filtering and isolating the indium oxide film is arranged on the top of the suction trough, and the feed pipe passes through the filter ring.

[0016] Furthermore, the vacuum pipeline and the nitrogen pipeline are both provided with control valves.

[0017] Furthermore, the kettle cover is provided with a pressure gauge for detecting the pressure in the raw material furnace.

[0018] Furthermore, the feed pipe is provided with a heating system, and the outer facade of the kettle is provided with a heat-insulating layer.

[0019] Furthermore, a method for using a feeding device of a continuous distillation and purification system for crude indium comprises the following steps:

[0020] S1: Open the lid of the kettle, put the indium raw material into the raw material crucible and cover the lid of the kettle;

[0021] S2: After starting the circulating water cooling system, open the vacuum system and continue to vacuumize;

[0022] S3: Turn on the constant temperature heating system of the kettle to start the material mixing, and at the same time turn on the heating system of the feed pipe;

[0023] S4: After the materials are dissolved, the vacuum system is closed and high-purity argon gas is introduced into the kettle to normal pressure;

[0024] S5: When the distillation of the previous batch of indium raw materials in the distillation furnace is completed, the feed valve is opened. At this time, the distillation furnace is in a vacuum state, the kettle body is at normal pressure, and the raw materials are sucked into the main furnace through the feed pipe;

[0025] S6: After feeding, close the feed valve and kettle heating, turn on the vacuum system, and turn off the pipeline heating after half an hour; after the whole temperature drops, turn off the vacuum system and wait for the next feeding.

[0026] Furthermore, during the S5 feeding process, raw material furnace pretreatment is performed synchronously, specifically including:

[0027] When the feed valve is opened, the circulating water cooling system of the raw material furnace is cooled to 150-200°C, and high-purity nitrogen is introduced through the nitrogen pipeline to purge the surface of the raw material crucible.

[0028] Furthermore, a dual-loop parallel mode is used to improve continuity, including:

[0029] When the remaining indium liquid in the distillation furnace is ≤10% of the raw material amount, the raw material furnace starts S3 feeding, and the distillation furnace still maintains vacuum distillation at this time; after the previous batch of distillation is completed, S5 feeding is immediately executed.

[0030] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0031] 1. Continuous production: Break through the limitations of batch operation, and use pressure difference to drive the feeding: Utilize the pressure difference between the vacuum of the distillation furnace and the normal pressure of the raw material furnace, and the feeding can be completed without the need for pump drive, thus avoiding the traditional discontinuous process of "cooling - opening the lid - filling".

[0032] Double cycle time staggered: the raw material furnace and the distillation furnace work in parallel, the material time (completely overlaps with the end of distillation (10% indium liquid remaining), the equipment idling time is reduced, and the quasi-continuous production of "discharging and preparing materials at the same time" is realized.

[0033] 2. Purity assurance: intercepting oxide film impurities at the source, filter ring + nitrogen purge: the filter ring at the top of the suction tank intercepts the oxide film on the surface of the indium liquid in real time, and cooperates with high-purity nitrogen micro-positive pressure purge to reduce the amount of oxide film brought in and the content of non-metallic impurities.

[0034] Closed process: The raw material furnace is operated in a closed manner throughout the process to avoid air contact, reduce the oxidation rate of the indium liquid, and eliminate secondary pollution from the source.

[0035] 3. Efficiency improvement: Automatic sewage discharge: The oxide film is discharged regularly through the bottom sewage outlet, and there is no need for manual furnace cleaning.

[0036] 4. Simplified operation: Pressure / temperature closed-loop control: The pressure gauge monitors the raw material furnace pressure in real time and automatically switches between vacuum / nitrogen modes; the frequency of manual intervention is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0038] Markings in the figure:

[0039] 1-distillation furnace, 2-raw material furnace, 3-feeding pipe, 4-feeding valve, 5-raw material crucible, 6-kettle body, 7-kettle cover, 8-vacuum pipeline, 9-nitrogen pipeline, 10-circulating water cooling system, 11-constant temperature heating system, 12-suction trough, 13-filter ring, 14-control valve, 15-pressure gauge, 16-insulation layer, 17-heating system.

[0040] Specific Examples

[0041] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0042] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] Embodiment 1

[0044] In this embodiment, if Figure 1 As shown, a feeding device of a continuous distillation and purification system of crude indium comprises: a distillation furnace, a raw material furnace and a feeding pipe, one end of the feeding pipe is arranged at the bottom of the raw material furnace, and the other end is arranged in the distillation furnace, and a feeding valve is arranged in the middle of the feeding pipe;

[0045] The raw material furnace comprises a raw material crucible, a kettle body and a kettle cover. The kettle body is sleeved on the outside of the raw material crucible. The kettle cover is provided with a vacuum pipeline and a nitrogen pipeline. The kettle body is provided with a circulating water cooling system and a constant temperature heating system.

[0046] Specifically: the distillation furnace (horizontal cylindrical, graphite lining) and the raw material furnace (vertical cylindrical, stainless steel kettle) are connected through a φ60mm feed pipe, and the feed valve is a pneumatic ball valve.

[0047] The suction trough at the bottom of the raw material furnace (50mm deep, 15° inclination) and the end of the feed pipe (10mm from the bottom of the trough) form a "liquid seal" to prevent the distillation furnace from vacuuming and sucking back air.

[0048] By utilizing the pressure difference between the vacuum of the distillation furnace and the normal pressure of the raw material furnace, the indium liquid can flow by itself without the need for a pump to drive it, thus avoiding batch cooling shutdowns.

[0049] Furthermore, the circulating water cooling system is connected to the kettle cover, and the circulating water inlet and outlet are arranged on the kettle cover.

[0050] The lid of the kettle is integrated with a spiral cooling water channel, which is injected from the top to avoid sudden cooling and cracking of the high temperature area at the bottom of the crucible.

[0051] Cooling water evenly cools the crucible from the top, which increases the life of the crucible.

[0052] Furthermore, a suction trough is provided at the bottom of the raw material crucible, and the end of the feed pipe is arranged in the suction trough.

[0053] The suction groove at the bottom of the raw material crucible is inverted cone shape, and 3 sets of guide fins are arranged in the groove to promote the indium liquid to gather to the feeding pipe.

[0054] Four side holes are processed at the end of the feed pipe to prevent the residue at the bottom of the tank from being sucked in.

[0055] The suction chute reduces the waste of raw materials and indirectly improves the purity.

[0056] Furthermore, a filter ring for filtering and isolating the indium oxide film is arranged on the top of the suction trough, and the feed pipe passes through the filter ring.

[0057] The filter ring is a sintered stainless steel mesh, nested on the top of the suction trough, and the feed pipe passes through the center.

[0058] During feeding, the indium liquid passes through the filter ring and the oxide film is intercepted in the tank, intercepting the oxide film impurities at the source and improving the purity.

[0059] Furthermore, the vacuum pipeline and the nitrogen pipeline are both provided with control valves.

[0060] The vacuum pipeline is equipped with a solenoid ball valve, and the nitrogen pipeline is equipped with a pneumatic regulating valve, which is interlocked with the feed valve:

[0061] Before feeding: fully open the vacuum valve and evacuate to vacuum within 30 seconds; when feeding: open the nitrogen valve to maintain a slight positive pressure in the raw material furnace. Avoid air back-inhalation during feeding, which will reduce the oxidation rate of the indium liquid.

[0062] Furthermore, the kettle cover is provided with a pressure gauge for detecting the pressure in the raw material furnace.

[0063] A digital pressure gauge is installed on the kettle cover and linked with the PLC: when the pressure is greater than 0.12MPa, the pressure relief valve is automatically opened; when the pressure is less than 0.08MPa, nitrogen is added.

[0064] The pressure fluctuation is controlled within ±5kPa to prevent the indium liquid from splashing due to excessive feeding and ensure safe operation.

[0065] Furthermore, the feed pipe is provided with a heating system, and the outer facade of the kettle is provided with a heat-insulating layer.

[0066] The feeding pipe is covered with a silicone electric heating belt, and the kettle body insulation layer is a rock wool + aluminum foil reflective layer. The heat loss of the feeding pipe is less than 5%, the surface temperature of the kettle body is ≤60℃, and the energy consumption is lower than that of the traditional process.

[0067] Embodiment 2:

[0068] A method for using a feeding device of a continuous distillation and purification system for crude indium comprises the following steps:

[0069] S1: Open the lid of the kettle, put the indium raw material into the raw material crucible and cover the lid of the kettle;

[0070] Open the raw material furnace cover manually and slide the crude indium block along the inner wall of the raw material crucible to avoid impacting the bottom suction groove.

[0071] When closing the kettle cover, the sealing ring automatically engages with the groove of the kettle body, and even pressure is applied through 4 sets of bolts to ensure airtightness.

[0072] Device association: The kettle cover integrates vacuum pipeline and nitrogen pipeline, and the pressure gauge displays the initial atmospheric pressure in real time.

[0073] S2: After starting the circulating water cooling system, open the vacuum system and continue to vacuumize;

[0074] Start the circulating water system, inject cooling water from the spiral channel on the top of the kettle cover, and lower the outer wall of the raw material crucible within 3 minutes.

[0075] At the same time, the vacuum valve was opened and the mechanical pump + molecular pump group was evacuating the air. After 10 minutes, the pressure gauge showed -0.095MPa (close to the ultimate vacuum).

[0076] Device association: The circulating water inlet and outlet are located on the kettle cover to prevent cooling water from directly flushing the high-temperature crucible.

[0077] S3: Turn on the constant temperature heating system of the kettle to start the material mixing, and at the same time turn on the heating system of the feed pipe;

[0078] The constant temperature heating (electromagnetic induction heating) of the kettle was turned on and the temperature was raised to 430°C within 30 minutes (the indium liquid was completely melted and the surface was mirror-like).

[0079] The heating system of the feed pipe is started synchronously (heating tape at 380°C), and the temperature in the middle of the pipe is detected by an infrared temperature measuring gun to reach 350°C to prevent condensation of indium liquid.

[0080] Maintain vacuum during chemical reaction to avoid oxidation of indium liquid. Occasional oxide films on the liquid surface are intercepted by subsequent filter rings.

[0081] S4: After the materials are dissolved, the vacuum system is closed and high-purity argon gas is introduced into the kettle to normal pressure;

[0082] Close the vacuum valve, slowly open the nitrogen valve, observe the pressure gauge until it reaches 0.1 MPa (normal pressure), and maintain for 30 seconds to purge the residual air in the kettle.

[0083] At this time, the raw material furnace is in a state of "slightly positive pressure + liquid indium", creating pressure difference conditions for S5 self-driven feeding.

[0084] S5: When the distillation of the previous batch of indium raw materials in the distillation furnace is completed, the feed valve is opened. At this time, the distillation furnace is in a vacuum state, the kettle body is at normal pressure, and the raw materials are sucked into the main furnace through the feed pipe;

[0085] Confirm the vacuum degree of the distillation furnace (through the pipeline pressure sensor linkage) and open the feed valve (pneumatic ball valve, 90° rotation to open).

[0086] The indium liquid enters the feed pipe due to the pressure difference and converges through the guide fins of the suction trough, forming a stable liquid flow within 30 seconds.

[0087] Device association: The end of the feed pipe is 10mm away from the bottom of the suction trough to avoid inhaling high-boiling point impurities precipitated at the bottom of the trough.

[0088] S6: After feeding, close the feed valve and kettle heating, turn on the vacuum system, and turn off the pipeline heating after half an hour; after the whole temperature drops, turn off the vacuum system and wait for the next feeding.

[0089] After the feeding is completed, close the feeding valve and immediately restart the vacuum system of the raw material furnace. The feeding pipe is heated for 10 minutes and then closed, and the residual indium liquid is purged using the residual temperature (>300°C) to prevent solidification and blockage.

[0090] The thermal insulation layer of the kettle body allows the residual heat of the chemical materials to maintain the raw material furnace at 150°C, thus reserving heat for the next batch of rapid heating.

[0091] Furthermore, during the S5 feeding process, raw material furnace pretreatment is performed synchronously, specifically including:

[0092] When the feed valve is opened, the circulating water cooling system of the raw material furnace is cooled to 150-200°C, and high-purity nitrogen is introduced through the nitrogen pipeline to purge the surface of the raw material crucible.

[0093] While the feed valve is opened, the circulating water system increases the flow rate (8L / min) and reduces the temperature of the raw material crucible from 430°C to 180°C within 5 minutes (to avoid long-term exposure to high-temperature indium liquid).

[0094] Nitrogen is introduced from the lid of the kettle, and the airflow spirals downward along the inner wall of the crucible, forming an "air curtain" above the liquid surface to inhibit oxidation.

[0095] After completing three feedings, the drain valve at the bottom of the kettle is opened manually to discharge the oxide film slag using the residual nitrogen pressure.

[0096] Furthermore, a dual-loop parallel mode is used to improve continuity, including:

[0097] When the remaining indium liquid in the distillation furnace is ≤10% of the raw material amount, the raw material furnace starts S3 feeding, and the distillation furnace still maintains vacuum distillation at this time; after the previous batch of distillation is completed, S5 feeding is immediately executed.

[0098] Distillation furnace: 0-5.5h (main distillation stage, 1120°C) → 5.5-6h (remaining 10% indium liquid, maintaining vacuum) → 6-6.1h (receiving feed).

[0099] Raw material furnace: 4.5-5.5h (start S3 material in advance, melt at 430℃) → 5.5-6h (wait for the distillation furnace signal) → 6-6.1h (execute S5 feeding).

[0100] Trigger condition: The weighing sensor of the distillation furnace detects that the remaining indium liquid is less than 10kg (preset value through PLC), and automatically sends a "prepare for material processing" signal to the raw material furnace.

[0101] The above description is only a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the invention should be included in the protection scope of the invention.

Claims

1. A feeding device for a continuous distillation and purification system of crude indium, characterized in that: include: A distillation furnace, a raw material furnace and a feed pipe, wherein one end of the feed pipe is arranged at the bottom of the raw material furnace, and the other end is arranged in the distillation furnace, and a feed valve is arranged in the middle of the feed pipe; The raw material furnace comprises a raw material crucible, a kettle body and a kettle cover, wherein the kettle body is sleeved outside the raw material crucible, the kettle cover is provided with a vacuum pipeline and a nitrogen pipeline, and the kettle body is provided with a circulating water cooling system and a constant temperature heating system.

2. A feeding device for a continuous distillation and purification system of crude indium according to claim 1, characterized in that: The circulating water cooling system is connected to the kettle cover, and the circulating water inlet and outlet are arranged on the kettle cover.

3. A feeding device for a continuous distillation and purification system of crude indium according to claim 1, characterized in that: A material suction trough is arranged at the bottom of the raw material crucible, and the end of the material delivery pipe is arranged in the material suction trough.

4. A feeding device for a continuous distillation and purification system of crude indium according to claim 3, characterized in that: A filter ring for filtering and isolating the indium oxide film is arranged on the top of the suction trough, and the feed pipe is arranged through the filter ring.

5. A feeding device for a continuous distillation and purification system of crude indium according to claim 1, characterized in that: The vacuum pipeline and the nitrogen pipeline are both provided with control valves.

6. A feeding device for a continuous distillation and purification system of crude indium according to claim 1, characterized in that: The kettle cover is provided with a pressure gauge for detecting the pressure in the raw material furnace.

7. A feeding device for a continuous distillation and purification system of crude indium according to claim 1, characterized in that: The feed pipe is provided with a heating system, and the outer facade of the kettle is provided with a heat-insulating layer.

8. A method for using a feed device for a continuous distillation purification system for crude indium, applied to a feed device for a continuous distillation purification system for crude indium according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Open the lid of the kettle, put the indium raw material into the raw material crucible and cover the lid of the kettle; S2: After starting the circulating water cooling system, open the vacuum system and continue to vacuumize; S3: Turn on the constant temperature heating system of the kettle to start the material mixing, and at the same time turn on the heating system of the feed pipe; S4: After the materials are dissolved, the vacuum system is closed and high-purity argon gas is introduced into the kettle to normal pressure; S5: When the distillation of the previous batch of indium raw materials in the distillation furnace is completed, the feed valve is opened. At this time, the distillation furnace is in a vacuum state, the kettle body is at normal pressure, and the raw materials are sucked into the main furnace through the feed pipe; S6: After feeding, close the feed valve and kettle heating, turn on the vacuum system, and turn off the pipeline heating after half an hour; after the whole temperature drops, turn off the vacuum system and wait for the next feeding.

9. The method for using a feeding device of a continuous distillation purification system for crude indium according to claim 8, characterized in that: During the S5 feeding process, the raw material furnace pretreatment is performed synchronously, including: When the feed valve is opened, the circulating water cooling system of the raw material furnace is cooled to 150-200°C, and high-purity nitrogen is introduced through the nitrogen pipeline to purge the surface of the raw material crucible.

10. The method for using a feeding device of a continuous distillation purification system for crude indium according to claim 8, characterized in that: The dual-circulation parallel mode is used to improve the continuity of feeding, including: When the remaining indium liquid in the distillation furnace is ≤10% of the raw material amount, the raw material furnace starts S3 feeding, and the distillation furnace still maintains vacuum distillation at this time; after the previous batch of distillation is completed, S5 feeding is immediately executed.

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