Method and equipment for separating, enriching and preparing hafnium chloride from zirconium chloride

Abstract

The invention belongs to the technical field of zirconium and hafnium element separation, and particularly relates to a method and equipment for preparing hafnium chloride from zirconium chloride through separation and enrichment. According to the separation method, zirconium chloride powder associated with hafnium is subjected to a reaction under the environment that the temperature is 140-180 DEG C and the vacuum degree is smaller than or equal to 30 Pa, so that hafnium chloride is in a gaseous state, and zirconium chloride is in a solid state. According to the method, the hafnium chloride associated with hafnium is taken as a raw material, the hafnium chloride is effectively separated and extracted from the hafnium chloride associated with hafnium by adopting a vacuum reduced-pressure fractionation process at a low temperature in a short process, and meanwhile, the grade of the hafnium chloride can be continuously improved through multiple times of cyclic enrichment.

Description

Technical Field

[0001] The invention belongs to the technical field of zirconium and hafnium element separation, and specifically relates to a method and equipment for separating and enriching hafnium chloride from zirconium chloride. Background Art

[0002] Zirconium and hafnium are important strategic rare metal elements. The content of zirconium (Zr) and hafnium (Hf) in the earth's crust belongs to the IVB group, respectively in the fifth and sixth periods of the periodic table of chemical elements. The two coexist and have very similar chemical properties. It is difficult to separate them from each other. Hafnium accounts for about 2% of the zirconium content. Sixth period. Zirconium has a small thermal neutron absorption cross section of only (0.18±0.02)*10 - 28 m 2 / atom, and has excellent corrosion resistance, making it an ideal structural material and cladding material for nuclear reactors. Atomic-grade hafnium has a high thermal neutron absorption cross section and can be used to prepare control rods for nuclear submarine reactors. At the same time, high-purity hafnium compounds can also be used in the field of semiconductor stress covariant layers. Hafnium fully replaces silicon dioxide as the latest generation of semiconductor high dielectric constant materials, breaking the limit of Moore's Law for the first time.

[0003] At present, people have carried out a lot of scientific research on the separation of zirconium and hafnium, and have developed a variety of separation process technologies, which can be roughly divided into two categories according to their characteristics: pyrometallurgy and hydrometallurgy.

[0004] Molten salt distillation is the only pyrometallurgical zirconium and hafnium separation process that has been industrialized. The specific steps are shown in the Chinese invention patents with announcement numbers CN112209436B and CN111994951B. It has the advantages of short process, low reagent consumption, and easy connection with front-end and back-end production processes. However, this type of process has high operating temperature, high energy consumption, high equipment investment and maintenance costs, and is difficult to promote and apply on a large scale. Molten salt extraction is another important pyrometallurgical zirconium and hafnium separation process. Its biggest advantage is the high single-step separation efficiency. Nuclear-grade quality products can be obtained through a one-step reaction, but the difficulty lies in the selection of alloys and molten salt systems. The current research system generally has the problem of low process efficiency and is difficult to meet the requirements of industrial applications.

[0005] The methods of hydrometallurgical separation of zirconium and hafnium mainly include fractional crystallization, ion exchange and solvent extraction, among which solvent extraction is the most important method for separating zirconium and hafnium in industry. Although traditional extractants MIBK and TBP can achieve selective extraction and separation of zirconium and hafnium, the single-step separation efficiency is low, and multi-stage extraction-strip extraction is required to obtain high-purity zirconium / hafnium products. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a method and equipment for separating and enriching hafnium chloride from zirconium chloride with high separation efficiency and good separation effect.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for separating and enriching hafnium chloride from zirconium chloride, reacting zirconium chloride powder with hafnium in an environment with a temperature of 140-180°C and a vacuum degree of ≤30Pa to obtain gaseous hafnium chloride and solid zirconium chloride, and then collecting the gaseous hafnium chloride.

[0008] Another technical solution adopted by the present invention is: a device for separating and enriching hafnium chloride from zirconium chloride, which is used in the above-mentioned method for separating and enriching hafnium chloride from zirconium chloride; the device includes a distillation furnace, a condensation collector connected to the distillation furnace in sequence, an air flow purifier and a vacuum pump system.

[0009] The beneficial effects of the present invention are as follows: the present invention designs a non-standard vacuum distillation furnace for the small difference in sublimation points between zirconium chloride and hafnium chloride; the distillation furnace uses liquid metal as a heating and heat transfer layer, can achieve precise temperature control, and improve separation efficiency; the present invention uses zirconium chloride associated with hafnium as a raw material, adopts vacuum reduced pressure fractionation process technology, effectively separates and extracts hafnium chloride from zirconium chloride associated with hafnium in a low temperature and short process, and can continuously improve the grade of hafnium chloride through multiple cycles of enrichment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of a device in a specific implementation manner of the present invention;

[0011] Description of labels:

[0012] 1. distillation furnace; 11. inner shell; 12. liquid metal layer; 13. outer shell; 14. rotating drum;

[0013] 2. Control power supply;

[0014] 3. Heating device;

[0015] 4. Condensation collector;

[0016] 5. Airflow purifier;

[0017] 6. Vacuum pump system; 61. Mechanical pump; 62. Screw pump. DETAILED DESCRIPTION

[0018] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0019] A method for preparing hafnium chloride by separation and enrichment from zirconium chloride, comprising reacting zirconium chloride powder associated with hafnium at a temperature of 140-180°C and a vacuum degree of ≤30Pa to obtain gaseous hafnium chloride and solid zirconium chloride, and then collecting the gaseous hafnium chloride.

[0020] From the above description, it can be seen that the beneficial effects of the present invention are: the current industrialization adopts solvent extraction wet technology, which has the problems of lengthy process flow, strong corrosion of equipment by the use of acids and alkalis, difficult-to-solve emulsification and coagulation during the reaction process of the extractant, and large output of three wastes.

[0021] The vacuum degree is inversely correlated with the sublimation temperature of hafnium chloride. The higher the vacuum degree is, the lower the sublimation temperature in the furnace is. The present invention uses a vacuum decompression fractionation process to separate zirconium chloride and hafnium chloride, and uses zirconium chloride associated with hafnium as a raw material to separate, enrich and extract hafnium chloride at low temperature and in a short process under a vacuum environment. The separation method is effective, has high separation efficiency, and is environmentally friendly.

[0022] Furthermore, after adding the zirconium chloride powder with associated hafnium, the powder is first evacuated to a vacuum degree of ≤1Pa, and then heated to a temperature of 140-180°C and a vacuum degree of ≤30Pa.

[0023] Preferably, after adding the zirconium chloride powder with associated hafnium, the powder is first evacuated to a vacuum degree of ≤1Pa, and then heated to a temperature of 150-170°C and a vacuum degree of 5-10Pa, 15-20Pa, or 25-30Pa.

[0024] From the above description, it can be seen that before heating, the vacuum degree in the equipment system is evacuated to ≤1Pa to reduce the influence of water vapor.

[0025] Furthermore, during the reaction process, the material is stirred at a speed of 1 to 20 r / min.

[0026] Preferably, the materials are stirred at a speed of 5 to 15 r / min during the reaction.

[0027] From the above description, it can be seen that the material reacts in a rotating state, and the reaction is more uniform.

[0028] Further, the gaseous hafnium chloride is collected by condensation.

[0029] Furthermore, the sum of the contents of zirconium chloride and hafnium chloride in the zirconium chloride powder containing associated hafnium is ≥ 98%.

[0030] From the above description, it can be seen that the higher the content of zirconium chloride and hafnium chloride, the less impurities, and the higher the grade of the separated hafnium chloride.

[0031] Furthermore, the particle size of the zirconium chloride powder associated with hafnium is ≤40 mesh.

[0032] From the above description, it can be seen that the finer the powder is, the larger the specific surface area is, and the more conducive it is to the sublimation of hafnium chloride.

[0033] Please refer to Figure 1 Another technical solution adopted by the present invention is: an equipment for separating and enriching hafnium chloride from zirconium chloride, characterized in that it is used in the above-mentioned method for separating and enriching hafnium chloride from zirconium chloride; the equipment includes a distillation furnace, a condensation collector connected to the distillation furnace in sequence, an air flow purifier and a vacuum pump system.

[0034] Furthermore, the distillation furnace includes an inner shell, a liquid metal layer, a heat-insulating layer and an outer shell which are arranged in sequence from the inside to the outside, and a rotating drum is arranged in the distillation furnace.

[0035] From the above description, it can be seen that during use, the zirconium chloride powder with associated hafnium is added to the drum, the distillation furnace is closed, and the vacuum in the complete set of equipment is evacuated to a vacuum degree of ≤1Pa by a vacuum pump system; then the distillation furnace is heated, and the temperature in the furnace is slowly raised to 140-180°C through the liquid metal layer in the distillation furnace, and the corresponding vacuum degree in the furnace is maintained at ≤30Pa; the material rotation system of the drum is synchronously turned on, and the speed is controlled to be 1-20r / min for reaction. The reaction lasts for a certain period of time, so that the hafnium chloride enters the condensation trap in gaseous form, and the condensation trap is connected to the airflow purifier to prevent trace powder from overflowing to the rear end; zirconium chloride is retained in the drum in solid form. After the reaction is completed, the temperature is lowered and the vacuum is released in turn, and the hafnium chloride material is collected in the condensation trap, and the zirconium chloride material is collected in the fractionation furnace body.

[0036] The equipment of the present invention realizes temperature control through the liquid metal layer, and the temperature control accuracy is ±1.0°C; the temperature of the liquid metal heat transfer layer is transferred to the furnace by setting the insulation layer, thereby reducing the heat loss. A rotating drum is set in the distillation furnace to make the material react dynamically, balance the heat in the furnace, and facilitate the effective and timely sublimation separation of hafnium chloride.

[0037] Furthermore, it also includes a control power supply, which is connected to the condensation collector, the airflow purifier and the vacuum pump system through electric wires.

[0038] Furthermore, it also includes a heating device arranged below the distillation furnace.

[0039] Furthermore, the heating device is any existing heating device.

[0040] It can be seen from the above description that the heating device is used to heat the liquid metal layer.

[0041] Furthermore, it also includes a temperature measuring system, which is used to measure the temperature inside the rotating drum.

[0042] Furthermore, the temperature measurement system includes a temperature sensor, and the temperature sensor is arranged on the inner wall of the drum.

[0043] Furthermore, the rotating drum is driven by an external motor to control the rotation speed and direction.

[0044] Furthermore, the equipment is placed in a dry and clean room with an air humidity of ≤8%.

[0045] From the above description, it can be seen that the equipment is placed in a dry and clean room to reduce the impact of water vapor.

[0046] Furthermore, the vacuum pump system includes a mechanical pump and a screw pump which are interconnected.

[0047] Furthermore, the condensate trap is cooled by jacket water.

[0048] Please refer to Figure 1 , Embodiment 1 of the present invention is: a device for separating and enriching hafnium chloride from zirconium chloride, comprising a distillation furnace 1, a control power supply 2, a temperature measurement system, a heating device 3 arranged below the distillation furnace 1, and a condensation collector 4, an airflow purifier 5 and a vacuum pump system 6 connected to the distillation furnace 1 in sequence. The distillation furnace 1 comprises an inner shell 11, a liquid metal layer 12, a heat preservation layer and an outer shell 13 arranged in sequence from the inside to the outside, and a rotating drum 14 is arranged in the distillation furnace 1, and the rotating drum 14 is controlled by an external motor drive to control the rotation speed and direction. The control power supply 2 is connected to the condensation collector 4, the airflow purifier 5 and the vacuum pump system 6 through wires. The temperature measurement system comprises a temperature sensor, which is arranged on the inner wall of the rotating drum 14 and is used to measure the temperature inside the rotating drum 14. The vacuum pump system 6 comprises a mechanical pump 61 and a screw pump 62 connected to each other. The condensation collector 4 is cooled by jacket water. The equipment is placed in a dry and clean room with an air humidity of ≤8%.

[0049] Embodiment 2 of the present invention is: a method for separating and enriching hafnium chloride from zirconium chloride using the equipment of embodiment 1, the steps are as follows:

[0050] In a dry and purified room with an air humidity of 8%, 20.0 kg of zirconium chloride powder raw material with a purity of 98.62% (including 0.745% hafnium chloride) and a particle size of ≤80 mesh is weighed, and the above raw materials are added into the drum 14, the distillation furnace 1 is closed, and the mechanical pump 61 is first turned on to evacuate the vacuum in the equipment to a vacuum degree of ≤500Pa, and then the screw pump 62 is turned on to evacuate the vacuum in the equipment to a vacuum degree of 1Pa; then the heating device 3 is turned on to heat the distillation furnace 1, and the material rotation system of the drum 14 is turned on synchronously, and the speed is controlled to be 5r / min. The temperature in the furnace is slowly raised to 170±1°C through the liquid metal layer 12 in the distillation furnace 1, and the corresponding vacuum degree in the furnace is maintained at 25-30Pa. The reaction lasts for 420 minutes, and the hafnium chloride enters the condensation collector 4 in gaseous form, and the excess airflow enters the airflow purifier 5 to prevent trace powder from overflowing to the rear end; the zirconium chloride is retained in the drum 14 in a solid form. After the reaction is completed, the heating is stopped, and the distillation furnace 1 is cooled naturally. When the temperature is lower than 60° C., the vacuum is released, and the hafnium chloride material is collected in the condensation collector 4, and the zirconium chloride material is collected in the furnace body of the fractionation furnace.

[0051] The material collected once by the condensation trap 4 was analyzed: 0.916 kg of hafnium chloride-rich material was collected by the condensation trap 4, and the hafnium chloride content thereof was 9.75 wt % as detected by ICP analysis.

[0052] The above method is used to repeatedly treat the hafnium chloride-rich material collected by the condensation trap 4 under the same conditions N times to continuously improve the purity of hafnium chloride. Take N=10 times for verification, and ICP analysis detects that the hafnium chloride content in the 10th collection material in the condensation trap 4 is 45.73wt%.

[0053] Embodiment 3 of the present invention is: a method for separating and enriching hafnium chloride from zirconium chloride using the equipment of embodiment 1, the steps are as follows:

[0054] In a dry and purified room with an air humidity of 8%, 20.0 kg of zirconium chloride powder raw material with a purity of 98.62% (including 0.745% hafnium chloride) and a particle size of ≤80 mesh is weighed, and the above raw materials are added into the drum 14, the distillation furnace 1 is closed, and the mechanical pump 61 is first turned on to evacuate the vacuum in the equipment to a vacuum degree of ≤500 Pa, and then the screw pump 62 is turned on to evacuate the vacuum in the equipment to a vacuum degree of 0.851 Pa; then the heating device 3 is turned on to heat the distillation furnace 1, and the material rotation system of the drum 14 is turned on synchronously, and the speed is controlled to 8 r / min. The temperature in the furnace is slowly raised to 160±1°C through the liquid metal layer 12 in the distillation furnace 1, and the corresponding vacuum degree in the furnace is maintained at 15-20 Pa. The reaction lasts for 640 minutes, and the hafnium chloride enters the condensation collector 4 in the gaseous form, and the excess airflow enters the airflow purifier 5 to prevent trace powder from overflowing to the rear end; the zirconium chloride is retained in the drum 14 in the solid form. After the reaction is finished, the heating is stopped, and the distillation furnace 1 is cooled naturally. When the temperature is lower than 60° C., the vacuum is released, and the hafnium chloride material is collected in the condensation collector 4, and the zirconium chloride material is collected in the fractionation furnace body.

[0055] The material collected once by the condensation trap 4 was analyzed: 0.806 kg of hafnium chloride-rich material was collected by the condensation trap 4, and the hafnium chloride content thereof was 11.38 wt % as detected by ICP analysis.

[0056] The above method is used to repeatedly treat the hafnium chloride-rich material collected by the condensation trap 4 under the same conditions N times to continuously improve the purity of hafnium chloride. Take N=10 times for verification, and ICP analysis detects that the hafnium chloride content in the 10th collection material in the condensation trap 4 is 52.51wt%.

[0057] Embodiment 4 of the present invention is: a method for separating and enriching hafnium chloride from zirconium chloride using the equipment of embodiment 1, the steps are as follows:

[0058] In a dry and purified room with an air humidity of 8%, 20.0 kg of zirconium chloride powder raw material with a purity of 98.62% (including 0.745% hafnium chloride) and a particle size of ≤80 mesh is weighed, and the above raw materials are added into the drum 14, the distillation furnace 1 is closed, and the mechanical pump 61 is first turned on to evacuate the vacuum in the equipment to a vacuum degree of ≤500 Pa, and then the screw pump 62 is turned on to evacuate the vacuum in the equipment to a vacuum degree of 0.51 Pa; then the heating device 3 is turned on to heat the distillation furnace 1, and the material rotation system of the drum 14 is turned on synchronously, and the speed is controlled to be 12 r / min. The temperature in the furnace is slowly raised to 150±1°C through the liquid metal layer 12 in the distillation furnace 1, and the corresponding vacuum degree in the furnace is maintained at 5-10 Pa. The reaction lasts for 540 minutes, and the hafnium chloride enters the condensation collector 4 in the gaseous form, and the excess airflow enters the airflow purifier 5 to prevent trace powder from overflowing to the rear end; the zirconium chloride is retained in the drum 14 in the solid form. After the reaction is finished, the heating is stopped, and the distillation furnace 1 is cooled naturally. When the temperature is lower than 60° C., the vacuum is released, and the hafnium chloride material is collected in the condensation collector 4, and the zirconium chloride material is collected in the fractionation furnace body.

[0059] The material collected once by the condensation trap 4 was analyzed: 0.795 kg of hafnium chloride-rich material was collected by the condensation trap 4, and the hafnium chloride content thereof was 11.97 wt % as detected by ICP analysis.

[0060] The above method is used to repeatedly treat the hafnium chloride-rich material collected by the condensation trap 4 under the same conditions N times to continuously improve the purity of hafnium chloride. Take N=10 times for verification, and ICP analysis detects that the hafnium chloride content in the 10th collection material in the condensation trap 4 is 57.48wt%.

[0061] Embodiment 5 of the present invention is:

[0062] The only technical features that distinguish the fifth embodiment from the first embodiment are that the reaction temperature is 180° C. and the rotation speed is 20 r / min.

[0063] Embodiment 6 of the present invention is:

[0064] The technical features that differ between Example 6 and Example 1 are that the temperature during the reaction is 140° C. and the rotation speed is 1 r / min.

[0065] Embodiment 7 of the present invention is: a method for separating and enriching hafnium chloride from zirconium chloride, adding 20.0 kg of zirconium chloride powder with a purity of 98.62% (wherein the hafnium chloride content is 0.745%) and a particle size of ≤80 mesh, first evacuating to a vacuum degree of 1 Pa, then heating to a temperature of 170° C., a vacuum degree of 25-30 Pa and reacting for 10 minutes, during the reaction process, the material is stirred at a speed of 5 r / min to obtain gaseous hafnium chloride and solid zirconium chloride, and the gaseous hafnium chloride is collected by condensation.

[0066] In summary, the method and device for separating and enriching hafnium chloride from zirconium chloride provided by the present invention have the following advantages:

[0067] 1. The vacuum decompression fractionation process technology is used to separate zirconium chloride and hafnium chloride, realizing low-temperature, short-process separation, enrichment and extraction of hafnium chloride. This separation method is effective, has high separation efficiency and is environmentally friendly.

[0068] 2. Before vacuum decompression fractionation, first evacuate the equipment system and place the equipment in a dry room to reduce the influence of water vapor.

[0069] 3. The material reacts in a rotating state, which improves the uniformity of the reaction and facilitates the effective and timely sublimation separation of hafnium chloride.

[0070] 4. Accurate temperature control is achieved through the liquid metal layer.

[0071] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for separating and enriching hafnium chloride from zirconium chloride, characterized in that: The zirconium chloride powder associated with hafnium is reacted at a temperature of 140-180° C. and a vacuum degree of ≤30 Pa to obtain gaseous hafnium chloride and solid zirconium chloride, and then the gaseous hafnium chloride is collected.

2. The method for separating and enriching hafnium chloride from zirconium chloride according to claim 1, characterized in that: After adding the zirconium chloride powder associated with hafnium, the vacuum is firstly evacuated to a degree of vacuum of ≤1Pa, and then heated to a temperature of 140-180°C and a degree of vacuum of ≤30Pa.

3. The method for separating and enriching hafnium chloride from zirconium chloride according to claim 1, characterized in that: During the reaction, the materials are stirred at a speed of 1 to 20 r / min.

4. The method for separating and enriching hafnium chloride from zirconium chloride according to claim 1, characterized in that: The gaseous hafnium chloride is collected by condensation.

5. The method for separating and enriching hafnium chloride from zirconium chloride according to claim 1, characterized in that: The sum of the contents of zirconium chloride and hafnium chloride in the zirconium chloride powder associated with hafnium is ≥98%.

6. The method for separating and enriching hafnium chloride from zirconium chloride according to claim 1, characterized in that: The particle size of the zirconium chloride powder associated with hafnium is ≤40 meshes.

7. A device for separating and enriching hafnium chloride from zirconium chloride, characterized in that: A method for separating and enriching hafnium chloride from zirconium chloride as described in any one of claims 1 to 6; the equipment comprises a distillation furnace, a condensation collector connected to the distillation furnace in sequence, an air flow purifier and a vacuum pump system.

8. The distillation furnace comprises an inner shell, a liquid metal layer, a heat-insulating layer and an outer shell which are arranged in sequence from the inside to the outside, and a rotating drum is arranged inside the distillation furnace.

9. The device according to claim 7, characterized in that The device also includes a control power supply, which is connected to the condensation collector, the airflow purifier and the vacuum pump system through electric wires.

10. The device according to claim 7, characterized in that The invention also comprises a heating device arranged below the distillation furnace.

Images