Neutralization reactor for solvent regeneration for separating zirconium and hafnium through MIBK method centrifugal extraction

Abstract

The invention relates to the technical field of hydrometallurgy production equipment, in particular to a neutralization reactor for regeneration of a solvent for separating zirconium and hafnium through MIBK method centrifugal extraction, which comprises a reactor body, a stirrer communicated with the reactor body and a cooling structure arranged in the reactor body, the reactor body is a hollow cylinder, and the stirrer comprises a stirring shaft rotationally connected in the middle of the interior of the reactor body and a stirring paddle fixed at the lower end of the stirring shaft; the reactor body comprises a lower shell and an upper shell, and the lower shell comprises an inner shell, an outer shell and a cavity located between the inner shell and the outer shell; the cooling structure comprises a spiral guide plate arranged in the cavity, a cooling liquid inlet formed in the lower end of the shell and a cooling liquid outlet formed in the upper end of the shell, and the cooling liquid inlet and the cooling liquid outlet are communicated with the cavity. By means of the reactor of a special structure, neutralization reaction heat in the solvent regeneration process can be removed in time, solvent decomposition and polymerization are prevented, and the extraction efficiency of the solvent is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgical production equipment, in particular to a neutralization reactor for solvent regeneration in centrifugal extraction and separation of zirconium and hafnium using a MIBK method. Background Art

[0002] Zirconium and hafnium are important materials in the nuclear industry. Hafnium, due to its large thermal neutron cross-section, is primarily used in the manufacture of control rods for nuclear reactors. Zirconium, due to its small thermal neutron cross-section, is primarily used in the manufacture of cladding and other structural materials for uranium fuel elements in nuclear reactors. Hafnium does not exist as a single mineral in nature; it is always found in association with zirconium ores. Due to the lanthanide contraction of zirconium and hafnium, their atomic and ionic radii are similar, resulting in very similar physical and chemical properties, making their separation extremely difficult. Hafnium is considered one of the most difficult elements to separate.

[0003] Currently, the most industrially viable process for separating zirconium and hafnium is methyl isobutyl ketone (MIBK) extraction. This method requires corresponding equipment, such as the prior art "Extraction Equipment for Hafnium and Zirconium Separation Process" (Publication No. CN220907580U). However, this equipment primarily focuses on the extraction and separation of hafnium and zirconium, and is unable to recycle the solvent. During the extraction and separation of zirconium and hafnium, the organic phase MIBK extractant loses its extraction capacity after multiple extraction cycles. To restore the MIBK extractant's extraction capacity and regenerate the solvent for recycling, ammonia is typically used to neutralize MIBK loaded with thiocyanate (HSCN) to produce ammonium thiocyanate (NH4SCN) and MIBK, allowing the NH4SCN and MIBK to be recycled. However, HSCN is extremely unstable. At temperatures above 20°C, it decomposes and polymerizes, forming large amounts of yellow elemental sulfur or polythiocyanate precipitates. These precipitates can emulsify the extraction system, resulting in a three-phase product, severely impacting extraction separation and production efficiency. Currently, solvent regeneration is mostly performed using a mixed-clarifier extractor or a neutralization reactor combined with an extraction tower. The mixed-clarifier extractor, however, cannot promptly remove the heat of the neutralization reaction, leading to localized overheating and partial decomposition and polymerization of the HSCN. This results in an emulsified, phase-inseparated extraction system and extremely low extraction efficiency. The neutralization reactor combined with an extraction tower is a complex system with numerous components, requiring significant space and space. This also fails to promptly remove the heat of the neutralization reaction, resulting in HSCN decomposition and polymerization, and a significant amount of emulsion remaining in the extraction system. Therefore, the market urgently needs a solvent regeneration device that can promptly remove the heat of the neutralization reaction. Summary of the Invention

[0004] The present invention provides a neutralization reactor for solvent regeneration in the centrifugal extraction and separation of zirconium and hafnium by the MIBK method, which can solve the problem that the existing solvent regeneration device cannot remove the neutralization reaction heat in time, causing the extraction system to emulsify and not separate into phases, thereby reducing the extraction efficiency.

[0005] The present application provides the following technical solution: a neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method, comprising a reactor body, an agitator connected to the reactor body, and a cooling structure disposed within the reactor body; The reactor body is a hollow cylinder, and the stirrer includes a stirring shaft rotatably connected to the middle of the reactor body and a stirring paddle fixed to the lower end of the stirring shaft; The reactor body includes a lower shell and an upper shell fixed above the lower shell, the lower shell includes an inner shell, an outer shell and a cavity located between the inner shell and the outer shell; the cooling structure includes a spiral guide plate arranged in the cavity, a cooling liquid inlet arranged at the lower end of the outer shell and a cooling liquid outlet arranged at the upper end of the outer shell, and the cooling liquid inlet and the cooling liquid outlet are connected to the cavity.

[0006] Beneficial effects: 1. Efficiently and quickly remove the reaction heat, preventing the HSCN in the solvent from decomposing or polymerizing due to the reaction heat to produce elemental sulfur or polymerized thiocyanate precipitates, thereby avoiding the subsequent emulsification of the extraction medium and improving the extraction efficiency of the extraction solvent. This device uses a reactor with a special structure as a solvent regeneration device. Compared with the existing solvent regeneration device, when the solvent is added to the reactor body, the stirring shaft is set in the middle of the reactor body. In this way, the neutralization reaction occurs in the center of the reactor inner shell during stirring. The stirring of the stirring paddle causes the mixed phase to diffuse toward the inner wall of the inner shell and gradually mix and transport upward. During this process, the coolant continuously enters the cavity between the inner shell and the outer shell from the coolant inlet. When the mixed phase contacts the inner shell, it will be cooled. The reaction heat generated by the neutralization of the solvent during stirring is transferred to the coolant. The coolant is finally discharged from the coolant outlet, thereby removing the reaction heat from the reactor body, achieving efficient and rapid removal of the reaction heat, preventing the regenerated extraction solvent from emulsification, and improving the extraction efficiency of the regenerated extraction solvent in subsequent recycling.

[0007] 2. Improved heat exchange efficiency. A spiral guide plate is used in the closed cavity formed by the inner and outer shells to force the coolant to flow upward along a spiral path within the cavity. On the one hand, its flow direction is the same as the upward discharge direction of the mixed phase during stirring, so that the mixed phase is in a heat exchange state throughout the process, improving heat exchange efficiency. On the other hand, the spiral guide plate extends the coolant flow path, increasing the contact area between the coolant and the inner shell, allowing the reaction heat inside the inner shell to be more fully transferred, significantly extending the heat exchange time, and further improving heat exchange efficiency.

[0008] Furthermore, the level of the coolant inlet is the same as the level of the stirring paddle.

[0009] Beneficial effects: The coolant inlet is at the same level as the stirring paddle, allowing the coolant to directly act on the mixing area in the reactor where the reaction is most intense and the heat release is most concentrated after entering the cavity, achieving precise cooling of the core reaction area. This design can quickly remove the local high heat generated during the stirring process, avoiding solvent degradation and polymerization caused by a sudden temperature rise in this area, thereby further reducing the risk of solvent emulsification, ensuring that the neutralization reaction is carried out efficiently at a stable temperature, and improving the quality of solvent regeneration and subsequent extraction efficiency.

[0010] Furthermore, the upper shell is connected with a solvent inlet and an ammonia water inlet, and a solvent feeding pipe is provided at the solvent inlet. If an ammonia water feeding pipe is provided at the ammonia water inlet, the solvent feeding pipe and the ammonia water feeding pipe are symmetrically arranged.

[0011] Beneficial effect: The solvent feeding pipe and the ammonia feeding pipe are symmetrically arranged, which enables the solvent and ammonia to enter from both sides of the upper part of the reactor at the same time and converge at the position of the stirring paddle, so that the two phases can achieve uniform contact at the early stage of the reaction, thereby improving the uniformity and efficiency of the neutralization reaction.

[0012] Furthermore, the lower ends of the solvent feeding pipe and the ammonia feeding pipe are bent toward the center of the stirring paddle.

[0013] Beneficial effects: The lower ends of the solvent feeding tube and the ammonia feeding tube are bent toward the center of the stirring paddle, which can enable the solvent and ammonia to be directly injected into the high-speed stirring area of ​​the stirring paddle. The strong shear force of the stirring paddle is used to achieve instant mixing, avoiding the materials from adhering to the wall of the vessel before sufficient contact or local accumulation due to gravity sedimentation, reducing the risk of local overheating caused by uneven reaction, and ensuring that the acidic degradation products react fully with the ammonia, thereby improving the neutralization efficiency.

[0014] Furthermore, the upper portion of the shell is also connected to a mixed phase outlet, and the setting height of the coolant outlet is higher than the setting height of the mixed phase outlet.

[0015] Beneficial effect: The coolant outlet height is higher than the mixed phase outlet, which makes the heat exchange area of ​​the inner wall of the inner shell larger, ensures that the coolant is fully filled in the cavity, and ensures that the mixed phase in the reactor can completely contact the inner wall of the inner shell for heat exchange before being discharged, so that the mixed phase undergoes a complete cooling process before being discharged, avoiding the problem of insufficient heat exchange of the mixed phase due to the short flow path of the coolant, thereby improving the effectiveness of heat exchange.

[0016] Furthermore, the stirrer also includes a motor and a coupling arranged above the upper shell, and the driving shaft of the motor is fixedly connected to the upper end of the stirring shaft through the coupling.

[0017] Beneficial effects: The structure in which the motor is connected to the stirring shaft through a coupling can ensure that the power of the motor main shaft is efficiently and stably transmitted to the stirring shaft, reducing power loss and transmission deviation, allowing the stirring paddle to maintain a uniform and stable speed, ensuring uniform mixing of the reaction system, and improving the reliability and stability of the overall operation of the equipment.

[0018] Furthermore, a pH meter, a thermometer and a liquid level meter are installed above the upper shell. The pH meter and the thermometer are arranged on one side away from the mixed phase outlet, and the liquid level meter is arranged at a symmetrical position on the other side.

[0019] Beneficial effects: The pH meter, thermometer and liquid level gauge installed above the upper shell can monitor the key parameters of the reaction system in real time. The pH meter and thermometer are located on the outlet side of the mixed phase, which can timely capture the pH and temperature changes after the neutralization reaction between the solvent and ammonia water, facilitating rapid adjustment of the amount of ammonia water added or the flow rate of the coolant; the liquid level gauge can accurately control the liquid level height of the mixed phase in the reactor to avoid material overflow due to excessively high liquid level or affecting the stirring effect due to too low liquid level.

[0020] Furthermore, a nitrogen inlet and an exhaust port for nitrogen sealing are connected above the upper shell.

[0021] Beneficial effects: The nitrogen inlet for nitrogen sealing connected to the top of the upper shell can introduce nitrogen into the reactor to seal the liquid surface, thereby preventing the organic vapor generated by solvent volatilization from forming an explosive mixed gas with the air above, and leaking out from the seal to encounter electrical sparks or other hot bodies (such as motor shafts, etc.) and explode; the exhaust port connected to the top of the upper shell is connected to a control valve, which can promptly discharge ammonia, MIBK vapor and water vapor generated during the neutralization reaction, avoid continuous accumulation of gas in the reactor, and balance the air pressure inside and outside the reactor, ensuring the stability of the feed and the controllability of the reaction system pressure, and ensuring the continuous and efficient progress of the neutralization reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the structural front view of the present invention. DETAILED DESCRIPTION

[0023] The following is further described in detail through specific implementation methods: The marks in the drawings of the specification include: reactor drain outlet 1, cavity drain outlet 2, lower shell 3, outer shell 301, cavity 302, inner shell 303, coolant outlet 4, thermometer 5, pH meter 6, solvent feeding pipe 7, solvent inlet 8, stirring shaft 9, coupling 10, motor 11, ammonia inlet 12, ammonia feeding pipe 13, exhaust port 14, liquid level meter 15, mixed phase outlet 16, stirring paddle 17, coolant inlet 18, upper shell 19, nitrogen inlet 20.

[0024] Example 1 like Figure 1 As shown, a neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by MIBK method includes a reactor body, an agitator connected to the reactor body, and a cooling structure arranged in the reactor body.

[0025] The reactor body is a hollow, approximately cylindrical body comprising a lower shell 3 and an upper shell 19 fixed above the lower shell 3. The lower shell 3 comprises an inner shell 303, an outer shell 301, and a cavity 302 formed by the inner shell 303 and the outer shell 301. The inner shell 303 and the outer shell 301 are fixed by welding, and the upper shell 19 is fixed to the upper end of the inner shell 303 by a flange. The bottom of the inner shell 303 is connected to the reactor sewage outlet 1, the bottom of the outer shell 301 is connected to the cavity sewage outlet 2, and the upper part of the outer shell 301 is also connected to the mixed phase outlet 16. Three vertical baffles evenly distributed in an annular direction are welded and fixed to the inner wall of the inner shell 303, which are omitted in the figure. They are used to increase the turbulence of the fluid and improve the efficiency of the chemical reaction. The entire upper shell 19 and the inner shell 303 are made of titanium, and the outer shell 301 is made of stainless steel.

[0026] The agitator includes a variable-frequency motor 11 mounted above the upper housing 19, a stirring shaft 9 rotatably connected to the center of the upper housing 19, and a stirring paddle 17 welded to the lower end of the stirring shaft 9. The drive shaft of the motor 11 is fixedly connected to the upper end of the stirring shaft 9 via a coupling 10. During installation, the motor 11 is screwed to a mounting bracket at the actual site. The stirring paddle 17 is located near the bottom of the inner housing 303.

[0027] The upper shell 19 is also connected to a solvent inlet 8 and an ammonia water inlet 12. A solvent feeding pipe 7 is installed at the solvent inlet 8, and an ammonia water feeding pipe 13 is provided at the ammonia water inlet 12. The solvent feeding pipe 7 and the ammonia water feeding pipe 13 are symmetrically arranged, and the lower ends of the solvent feeding pipe 7 and the ammonia water feeding pipe 13 are bent toward the center of the stirring paddle 17.

[0028] A pH meter 6, a thermometer 5, and a liquid level gauge 15 are also mounted above the upper housing 19. The pH meter 6 and thermometer 5 are positioned on a side away from the mixed phase outlet 16, while the liquid level gauge 15 is positioned symmetrically on the other side. The pH meter 6, thermometer 5, and liquid level gauge 15 are all inserted through the mounting opening into the cavity of the inner housing 303 to monitor the pH value, temperature, and liquid level within the reactor. The thermometer 5 and pH meter 6 are provided with protective tubes uniformly perforated with small holes to protect the thermometers 5 and 6 from fluid impact. A nitrogen inlet 20 and an exhaust port 14 are also connected above the upper housing 19. The exhaust port 14 is connected to a solenoid valve and is used to discharge waste gases such as ammonia, MIBK vapor, and water vapor generated within the reactor. The nitrogen inlet 20 allows nitrogen to enter the reactor to seal the liquid surface, preventing organic vapors generated by solvent evaporation from forming an explosive mixture with the air above. Leakage through the seal could cause an explosion upon contact with electrical sparks or other hot objects (such as a motor shaft).

[0029] The cooling mechanism includes a spiral guide plate arranged in the cavity 302, a coolant inlet 18 arranged at the lower end of the shell 301 and a coolant outlet 4 arranged at the upper end of the shell 301. The coolant inlet 18 and the coolant outlet 4 are connected to the cavity 302. The spiral guide plate is spirally wound upward in the cavity 302, so that the cooling medium entering from the coolant inlet 18 will gradually flow upward along the spiral guide plate, and finally be discharged through the coolant outlet 4. The spiral guide plate in the figure is omitted.

[0030] The level of the cooling liquid inlet 18 is the same as that of the stirring paddle 17, so that the cooling liquid can directly act on the mixing area in the reactor where the reaction is most intense and the heat release is most concentrated after entering the cavity 302, thereby achieving precise cooling of the reaction core area.

[0031] The setting height of the coolant outlet 4 is higher than the setting height of the mixed phase outlet 16, which can increase the heat exchange area of ​​the inner wall of the inner shell 303 and ensure that the mixed phase in the reactor can completely contact the inner wall of the inner shell 303 for heat exchange before being discharged, so that the mixed phase undergoes a complete cooling process before being discharged, avoiding the problem of insufficient heat exchange of the mixed phase due to the short flow path of the coolant, thereby improving the effectiveness of heat exchange.

[0032] The method of using this device is as follows: During use, the MIBK solvent to be regenerated is added to the inner shell 303 through the solvent feeding pipe 7. At the same time, ammonia water is injected into the inner shell 303 through the ammonia water feeding pipe 13. The two materials flow to the center of the stirring paddle 17 under the guidance of the feeding pipe. The stirring shaft 9 and the stirring paddle 17 are driven by the variable frequency motor 11 to stir. The vertical baffle of the inner shell 303 enhances turbulence to promote the neutralization reaction. At the same time, the cooling medium is introduced from the cooling liquid inlet 18 at the lower end of the outer shell 301. The cooling medium flows upward along the spiral guide plate in the cavity 302, exchanges heat with the reaction system in the inner shell 303, and is discharged from the cooling liquid outlet 4 at the upper end. Since the cooling liquid inlet 18 and the stirring paddle 17 are located at the same height, the cooling medium is discharged from the upper end of the cooling liquid outlet 4. The coolant outlet 4 is higher than the mixed phase outlet 16, which can accurately control the temperature of the reaction core area; during the reaction, the pH meter 6 and thermometer 5 of the upper shell 19 are used to monitor the reaction pH and temperature on the side of the solvent inlet 8 in real time, the liquid level meter 15 monitors the liquid level on the side of the ammonia inlet 12, and the exhaust port 14 discharges the waste gas generated by the reaction in time. The mixed phase after the reaction is completed is discharged by overflow through the mixed phase outlet 16 on the upper part of the outer shell 301. If it is necessary to clean the dirt in the inner shell 303 or the cavity 302, the residue can be discharged through the reactor drain port 1 at the bottom of the inner shell 303 and the cavity drain port 2 at the bottom of the outer shell 301 respectively.

[0033] The above are only embodiments of the present invention. The invention is not limited to the fields involved in this implementation case. Common knowledge such as the specific structure and characteristics of the scheme are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A neutralization reactor for solvent regeneration in the centrifugal extraction and separation of zirconium and hafnium by the MIBK method, characterized in that: It includes a reactor body, an agitator connected to the reactor body, and a cooling structure arranged in the reactor body; The reactor body is a hollow cylinder, and the stirrer includes a stirring shaft rotatably connected to the middle of the reactor body and a stirring paddle fixed to the lower end of the stirring shaft; The reactor body includes a lower shell and an upper shell fixed above the lower shell, the lower shell includes an inner shell, an outer shell and a cavity located between the inner shell and the outer shell; the cooling structure includes a spiral guide plate arranged in the cavity, a cooling liquid inlet arranged at the lower end of the outer shell and a cooling liquid outlet arranged at the upper end of the outer shell, and the cooling liquid inlet and the cooling liquid outlet are connected to the cavity.

2. The neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 1, characterized in that: The level of the coolant inlet is the same as that of the stirring paddle.

3. A neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 2, characterized in that: The upper shell is connected with a solvent inlet and an ammonia water inlet. A solvent feeding pipe is provided at the solvent inlet. If an ammonia water feeding pipe is provided at the ammonia water inlet, the solvent feeding pipe and the ammonia water feeding pipe are symmetrically arranged.

4. A neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 3, characterized in that: The lower ends of the solvent feeding pipe and the ammonia water feeding pipe are bent toward the center of the stirring paddle.

5. The neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 4, characterized in that: The upper portion of the shell is also connected to a mixed phase outlet, and the setting height of the coolant outlet is higher than the setting height of the mixed phase outlet.

6. The neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 5, characterized in that: The stirrer further comprises a motor and a coupling arranged above the upper shell, and the driving main shaft of the motor is fixedly connected to the upper end of the stirring shaft through the coupling.

7. A neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 6, characterized in that: A pH meter, a thermometer and a liquid level meter are also installed above the upper shell. The pH meter and the thermometer are arranged on the mixed phase outlet side, and the liquid level meter is arranged at a symmetrical position on the other side.

8. The neutralization reactor for solvent regeneration for centrifugal extraction and separation of zirconium and hafnium by the MIBK method according to claim 7, characterized in that: The upper portion of the upper shell is also connected with a nitrogen inlet and an exhaust port.

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