CN113462903A - Metal purification device and purification method - Google Patents

Abstract

The invention discloses a metal purification device and a metal purification method, and belongs to the field of metal purification. The device comprises a vacuum box body, wherein the interior of the vacuum box body is in a vacuum state, and a fixing mechanism, a crucible, a heater and a lifting mechanism are arranged in the vacuum box body; the fixing mechanism is used for fixing the crucible, the crucible is provided with an accommodating cavity, the shape and the size of the accommodating cavity are matched with those of a metal sample to be purified, the heater is arranged around the crucible and is matched with the shape of the crucible, and the lifting mechanism is used for lifting the heater. The method adopts the purification device, and effectively solves the problems that the existing vertical zone melting device can not purify large-size metal and has low preparation efficiency.

Description

Metal purification device and purification method

Technical Field

The invention belongs to the technical field of metal purification, and particularly relates to a metal purification device and a metal purification method.

Background

The rapid development of information technology and high-end communication technology makes the requirements of semiconductor industry on the purity of metal raw materials more and more strict, and the improvement of the purity of the metal raw materials usually forms order of magnitude improvement on the performance of the metal raw materials. The purification method of metals such as antimony, indium, germanium and the like which is widely applied at present mainly comprises a vacuum distillation method, a zone melting method, a single crystal Czochralski method and the like. The vacuum distillation method has the advantages that from the practical production perspective, particularly, the high-temperature vacuum distillation greatly reduces the product yield; the single crystal Czochralski method has the disadvantages of large equipment investment, complex process and higher requirement on operators. In contrast, the highly automated zone melting process is receiving increasing attention, and the number of inventions related to purification by the zone melting process is rapidly increasing. However, when the high-purity metal is prepared by the traditional horizontal zone melting method, the cooling system of the zone melting device is difficult to apply, the complex solid-liquid interface shape often causes that the enriched regions formed at the two ends of the impurity element are difficult to fix, and the optimization is often difficult to realize when the horizontal zone melting purified sample is cut at the two ends.

The Chinese patent application numbers are: CN201911239129.7, published date: the patent document 3/27/2020 discloses a zone melting device and a zone melting method for high-purity indium, which adopt targeted overweight reinforcement zone melting and solve the problem of difficult separation when the separation coefficient of part of impurity elements in the traditional horizontal zone melting is close to 1 under the combined action of supergravity and a strong magnetic field. However, the method still belongs to a horizontal zone melting method, and the complex supergravity zone melting environment thereof makes the method difficult to popularize on a large scale, and the optimization is difficult to realize when the two ends of the sample are cut.

The Chinese patent application numbers are: cn201910606312.x, published as: the patent document of 2019, 9 and 20 discloses a device integrating vacuum distillation and vertical zone melting and a preparation method, the precise control of the temperature zone height and the solid-liquid interface shape is realized through the combination of resistance wire heating and a cold trap cooling system, so that impurity elements are completely enriched at two ends of a sample, and the two ends can be cut in parallel after multi-pass vertical zone melting to prepare the ultra-pure indium with the purity level of 99.99999%. Although the device belongs to vertical zone-melting purification, the problems commonly existing in the existing scheme related to the vertical zone-melting method exist, namely the existing vertical zone-melting method commonly adopts a tubular quartz crucible, a ring-shaped resistance wire or an electromagnetic induction heating mode, and the enlargement of the size of a metal sample inevitably causes the aggravation of the axial and radial temperature difference inside the melt, so the invention of the patent for purifying the metal related to the vertical zone-melting disclosed at present is only suitable for small-diameter samples, has low preparation efficiency and is difficult to be applied to the purification of large-size products, thereby greatly limiting the industrial application of the method, and the vertical zone-melting device and the method specially used for purifying the large-size metal do not exist at present.

Disclosure of Invention

1. Problems to be solved

The invention provides a metal purification device and a purification method, aiming at solving the problems that the preparation efficiency of a vertical zone melting device in the prior art is low, the vertical zone melting device cannot be suitable for large-size metal purification, and the industrial application of vertical zone melting is limited.

2. Technical scheme

In order to solve the above problems, the present invention adopts the following technical solutions.

A metal purification device comprises a vacuum box body, wherein the inside of the vacuum box body is in a vacuum state, and a fixing mechanism, a crucible, a heater and a lifting mechanism are arranged in the vacuum box body; the fixing mechanism is used for fixing the crucible, the crucible is provided with an accommodating cavity, the shape and the size of the accommodating cavity are matched with those of a metal sample to be purified, the heater is arranged around the crucible and is matched with the shape of the crucible, and the lifting mechanism is used for lifting the heater.

As a further improvement of the technical scheme, the fixing mechanism comprises a top fixing table, a bottom fixing table and a lifter; the top fixing table is installed at the top of the vacuum box body, the lifter is installed at the bottom of the vacuum box body, and the bottom fixing table is installed on the lifter; the crucible is fixed between the top fixing table and the bottom fixing table.

As a further improvement of the technical scheme, grooves matched with the shape of the crucible are respectively formed in the lower end face of the top fixing table and the upper end face of the bottom fixing table.

As a further improvement of the technical scheme, a screw hole penetrating through the top fixing table or the bottom fixing table is formed in the top fixing table or the bottom fixing table on two sides of the groove, and a fastening bolt penetrates through the screw hole.

As a further improvement of the technical scheme, the crucible heating device further comprises two magnetic field coils which are arranged around the crucible and matched with the shape of the crucible, wherein the two magnetic field coils are an upper end magnetic field coil positioned above the heater and a lower end magnetic field coil positioned below the heater.

As a further improvement of the technical scheme, the lifting mechanism comprises a motor, a sliding block, a screw rod and a bearing; the motor is arranged outside the vacuum box body, the screw rod is vertically arranged inside the vacuum box body, and the bearing is fixed on the inner side wall of the vacuum box body; an output shaft of the motor is in transmission connection with one end of a screw rod, and the other end of the screw rod is connected with a bearing; the screw rod is sleeved with a nut, the nut is fixedly connected with a nut seat, the sliding block is fixedly connected with the nut seat, and the heater and the magnetic field coil are fixedly connected with the sliding block.

As a further improvement of the technical scheme, a middle limiting block is arranged on one side, close to the screw rod, of the bottom fixing table and is located under the sliding block.

As a further improvement of the technical scheme, the cross section of the metal sample to be purified is in a shape of a flat plate, a cambered plate, a curved plate or a circular ring.

As a further improvement of the technical scheme, the ratio of the width to the thickness of the sample is more than or equal to 2, and the maximum thickness of the sample is less than or equal to 2 times of the height of the maximum melting area of the metal.

As a further improvement of the technical scheme, a vacuum pump is arranged outside the vacuum box body and is communicated with the vacuum box body through a vacuumizing pipe; the side wall of the vacuum box body is provided with an air release port, and a sealing plug is plugged in the air release port.

As a further improvement of the technical scheme, a protective gas tank is further arranged outside the vacuum box body and communicated with the vacuum box body through a protective gas pipe.

A metal purification method comprising the following operative steps:

firstly, installing a sample: putting a metal sample into a crucible, and fixing the crucible by a fixing mechanism;

secondly, vacuumizing: sucking air in the vacuum box body to enable the interior of the vacuum box body to reach a set vacuum degree;

thirdly, electrifying: electrifying the heater to a set temperature, and electrifying the magnetic field coil to set parameters if the sample needs to be purified in a magnetic field environment;

fourthly, purification: controlling the heater and the magnetic field coil to ascend from the lower end of the crucible through the lifting mechanism, descending after reaching the upper end of the crucible, and repeatedly lifting the heater and the magnetic field coil until impurity elements are gathered and separated at the upper end and the lower end of the sample;

fifthly, taking out a sample: powering off the heater and the magnetic field coil, enabling the internal and external air pressures of the vacuum box body to be consistent after the sample is cooled, then opening the vacuum box body, enabling the fixing mechanism to loosen the crucible, and then taking out the sample;

sixthly, cutting a sample: cutting off the preset parts of the upper end and the lower end of the sample, wherein the rest part is the purified product.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention relates to a metal purification device, which leads the metal of a heating part to realize the zone melting in a crucible by ascending and descending a heating device in the height direction of a sample, leads impurity elements in the metal of the melting part to move upwards or downwards in a single direction according to the redistribution rule of solute, repeatedly ascends and descends the heater to drive different types of impurity elements to move upwards or downwards in a single direction respectively, in particular, the shape and the size of the crucible of the device are matched with the shape and the size of the sample, when the metal is melted in the crucible and is changed into a melting state, the shape of the metal is basically kept unchanged, so that an oxide layer on the surface of the metal can be still maintained on the surface of the molten metal after the metal is changed into the melting state, the position of the oxide layer is basically kept unchanged after the metal is cooled, thereby playing the role of blocking between the metal and the inner wall of the crucible, and being convenient for taking out the sample from the crucible, meanwhile, the heater is arranged around the crucible and matched with the crucible in shape, so that the heater can uniformly heat the sample along the circumferential direction of the sample, and the problem that the purification effect of the metal is influenced due to uneven metal melting caused by large temperature gradient of the sample in the thickness direction when the existing device heats the large-size sample is solved;

(2) according to the metal purification device, the top fixing table, the bottom fixing table and the lifter can be used for quickly and conveniently fixing large-size samples, so that conditions are provided for realizing high-efficiency purification work of the metal samples;

(3) according to the metal purification device, the grooves matched with the shape of the sample are respectively formed in the lower end face of the top fixing table and the upper end face of the bottom fixing table, so that the sample can be pre-fixed and fixed more accurately, and meanwhile, the fixing effect is further enhanced by arranging the fastening bolts at the two sides of the grooves;

(4) according to the metal purification device, the magnetic field is applied simultaneously in the heating process, the separation efficiency of impurity elements can be accelerated, the impurity elements are concentrated at the upper position or the lower position respectively, the purification of the whole sample is completed, the magnetic field coils are arranged above and below the heater respectively, the stability of the magnetic field intensity acting on the regional molten melt can be ensured, the influence of the magnetic field on the melt of the regional molten melt is further ensured to be relatively stable, and during actual operation, direct current, alternating current and pulse current can be introduced into the magnetic field coils, so that a static magnetic field, an alternating magnetic field and a pulse magnetic field are generated and applied to a metal melt and a solid-liquid interface, the regulation and control of a temperature field, a flow field and a solute field are realized, the operation is flexible, and the adaptability is wide;

(5) according to the metal purification device, the middle limiting block is arranged on one side, close to the screw rod, of the bottom fixing table, so that on one hand, the maximum moving distance of the lower end magnetic field coil can be limited, the lower end magnetic field coil is prevented from being damaged due to collision with the bottom fixing table, on the other hand, the set lowest position of the heater can be positioned, the initial heating position of a sample is more accurate, and the purification effect is improved;

(6) compared with the conventional device which can only purify small-size metal, when large-size metal is purified, metal melting is unstable due to uneven heating of the metal at each position in the thickness direction, and purification is influenced;

(7) the metal purification method can realize vertical zone melting purification of large-size metal and greatly improve the preparation efficiency of a vertical zone melting technology by adopting the purification device.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the heater of FIG. 1 rising to the middle;

FIG. 3 is a schematic view of the top mounting plate of the present invention;

FIG. 4 is a schematic cross-sectional view of various different gauge samples and heaters of the present invention, wherein: (a) the cross section state diagram of a flat plate-shaped sample and a heater is shown, (b) the cross section state diagram of a cambered plate-shaped sample and the heater is shown, (c) the cross section state diagram of a curved plate-shaped sample and the heater is shown, and (d) the cross section state diagram of an annular sample and the heater is shown;

in the figure: 1. a vacuum box body; 2. a top fixed table; 3. a crucible; 4. an upper end magnetic field coil; 5. a heater; 6. a lower end magnetic field coil; 7. protecting the air pipe; 8. a protective gas tank; 9. an air release port; 10. vacuumizing a tube; 11. a vacuum pump; 12. a lifter; 13. a middle limiting block; 14. a motor; 15. a heater controller; 16. a magnetic field power supply controller; 17. a slider; 18. a screw rod; 19. a bearing; 20. fastening a bolt; 21. a connecting table; 22. a bottom fixed table; 23. a valve; 24. a flat plate-like sample; 25. cambered surface plate-shaped samples; 26. a curvilinear plate-like sample; 27. a circular sample.

Detailed Description

The invention is further described with reference to specific embodiments and the accompanying drawings.

Examples

A metal purifying apparatus for purifying metal, especially large-sized metal samples, by a vertical zone melting technique is described in detail below with reference to the specific structure and operation of the apparatus.

As shown in fig. 1 to 2, the apparatus includes a vacuum chamber 1, and a sample fixing mechanism, a crucible 3, a heater 5, a magnetic field coil, and a lifting mechanism are provided in the vacuum chamber 1 during operation.

Wherein the fixing mechanism comprises a top fixing table 2, a bottom fixing table 22 and a lifter 12. The top fixed station 2 is installed at the top of the vacuum box body 1, the lifter 12 is installed at the bottom of the vacuum box body 1, the bottom fixed station 22 is installed on the lifter 12 and is located under the top fixed station 2, and the crucible 3 is fixed between the top fixed station 2 and the bottom fixed station 22. The crucible 3 is provided with a containing cavity for placing a sample, and the shape and the size of the containing cavity are matched with those of a metal sample to be purified, so that when the sample is placed into the crucible 3, gaps between various positions of the sample and the inner wall of the crucible 3 are kept consistent and small (generally not more than 1mm), and therefore when the metal is melted in the crucible 3 and is changed into a molten state, the shape of the metal is basically kept unchanged, and the purification of the metal cannot be influenced by the deformation of the metal. Meanwhile, when the metal is in a solid state, the oxide layer on the surface of the metal can be still maintained on the surface of the molten metal after the metal is changed into a molten state, and the position of the oxide layer basically keeps unchanged after the metal is cooled, so that a separation effect is achieved between the metal and the inner wall of the crucible 3, and a sample can be conveniently taken out of the crucible 3.

Specifically, be provided with a plurality of between 1 top inner wall of top fixed station 2 and vacuum box and connect the platform 21, through connecting platform 21 with top fixed station 2 unsettled fixed. The top of connecting the platform is fixed through welding or other fixed modes with the inside of vacuum box 1, and the bottom of connecting the platform passes top fixed station 2 through the bolt after closely pasting with top fixed station 2, screws up and enters into and connects the platform, fixes top fixed station 2. The lifter 12 may adopt some lifting devices commonly used in the prior art, such as an air cylinder, a hydraulic cylinder, a screw lifting mechanism, etc., and in order to ensure that the operation of the lifter 12 is not affected by the vacuum state, the lifter 12 of the present embodiment has the following structure in consideration of the vacuum state in the vacuum box 1 during operation.

A plurality of threaded holes are formed in the bottom fixing table 22, the lifter 12 comprises a plurality of rotary rods, threads matched with the threaded holes are arranged on the outer sides of the upper half sections of the rotary rods, and the rotary rods are connected in the threaded holes of the bottom fixing table 22 in a threaded mode. Meanwhile, the bottom of each rotating rod is inserted into a bearing, the outside of the bearing is fixed with the bottom of the vacuum box 1, all the rotating rods are connected with a motor arranged outside the vacuum box through a transmission member respectively to realize synchronous driving, the motor drives all the rotating rods to rotate synchronously through the transmission member, and the ascending or descending of the bottom fixing table 22 is realized by controlling the forward rotation or the reverse rotation of the rotating rods. Since the specific connection structure of the motor and the rotating rod belongs to the prior art that should be known to those skilled in the art, it will not be described in detail herein.

In order to further improve the fixing effect of the crucible 3, the lower end surface of the top fixing table 2 and the upper end surface of the bottom fixing table 22 are respectively provided with a groove matched with the shape of the crucible 3. The top fixed station 2 or the bottom fixed station 22 on the two sides of the groove are provided with screw holes penetrating through the top fixed station 2 or the bottom fixed station 22, and fastening bolts 20 penetrate through the screw holes. After the crucible 3 is fixed, the fastening bolt 20 is screwed, and the fastening bolt 20 can be abutted to compress the crucible 3.

When installing the sample, put into crucible 3 with crucible 3 upper end cover sealed with the sample, crucible 3 bottom is inserted in the recess of bottom fixed station 22 at first, then with the fastening bolt 20 of bottom fixed station 22 both sides screw up fixed crucible 3, then rise bottom fixed station 22, let crucible 3's top insert in the recess of top fixed station 2, then fastening bolt 20 of top fixed station 2 both sides screws up fixed crucible 3. When taking out the sample, the fixing bolt 20 at the top of the crucible 3 is loosened, the height of the bottom fixing table 22 is lowered, the top of the crucible 3 is separated from the groove of the top fixing table 2, the bottom fixing table 22 is stopped, the fastening bolt 20 on the bottom fixing table 22 is loosened, the crucible 3 is opened after the crucible 3 is clamped by the clamp, and the sample is clamped from the crucible 3 by the clamp.

In the present embodiment, the shape and number of the grooves are selected according to the shape and number of the crucible 3. When the crucible 3 has a quadrangular cross section, the top fixing table 2 is provided in a structure as shown in fig. 3, so that the crucible 3 can be smoothly inserted into the recess. When the crucible 3 is in the form of a flat plate, a cambered plate, a curved plate or a circular ring as shown in fig. 4, the recess of the holding table should also match the shape of the crucible 3. Meanwhile, the number and shape of the grooves are determined according to the number and shape of the crucibles 3 to be fixed, and a plurality of samples can be purified at the same time.

The heater 5 and the magnetic field coil are arranged around the crucible 3, and the elevating mechanism is used for elevating the heater 5 and the magnetic field coil.

Specifically, the lifting mechanism comprises a motor 14, a slide block 17, a screw rod 18 and a bearing 19. The motor 14 is arranged outside the vacuum box body 1, the screw rod 18 is vertically arranged inside the vacuum box body 1 and close to the inner side wall of the vacuum box body 1, and the bearing 19 is fixed on the inner side wall of the vacuum box body 1. The driving shaft of the motor 14 is connected with a speed reducer, the driving shaft of the speed reducer is inserted into the vacuum box body 1, the driving shaft is connected with one end of a screw rod 18 through a steering connector, the screw rod 18 is driven to rotate when the motor 14 is started, and the other end of the screw rod 18 is connected with a bearing 19. The screw rod 19 is sleeved with a nut which is fixedly connected with a nut seat, the sliding block 17 is fixedly connected with the nut seat, and the heater 5 and the magnetic field coil are fixedly connected with the sliding block 17. The screw rod 18 is driven to rotate by controlling the work of the motor 14, when the screw rod 18 rotates clockwise, the slide block 17 rises, and when the screw rod 18 rotates anticlockwise, the slide block 17 falls.

In the present invention, the number of the magnetic field coils is two, and the two magnetic field coils are an upper end magnetic field coil 4 located above the heater 5 and a lower end magnetic field coil 6 located below the heater 5. The two magnetic field coils and one side of the heater 5 are fixedly connected with a sliding block 17, and the three can be respectively connected with one sliding block 17 or can be jointly connected with the same sliding block 17.

In addition, one side of the bottom fixing table 22 close to the screw rod 18 is provided with a middle limiting block 13, the middle limiting block 13 is positioned under the sliding block 17, and the top of the middle limiting block 13 is higher than the upper surface of the bottom fixing table 22. On one hand, the maximum moving distance of the lower end magnetic field coil 6 can be limited, the lower end magnetic field coil is prevented from being damaged due to collision with the bottom fixing table 22, and on the other hand, the set lowest position of the heater 5 can be positioned, so that the initial heating position of the sample is more accurate, and the purification effect is improved.

It should be noted that in this embodiment, the heater 5 and the magnetic field coil are not simply arranged around the crucible 3, and the specific shape of the ring needs to be changed to match the specific shape of the metal sample, so as to ensure that the minimum distance from each position outside the metal sample to the heater 5 or the magnetic field coil is consistent, so that the purification of the metal sample is uniform, and the purification effect is better, therefore, the metal sample and the crucible 3 need to be kept in a cylindrical structure with the side wall extending along the height direction. As shown in fig. 4, the shape adaptability of the heater 5 and the magnetic field coil changes to accommodate metal samples of different shapes.

It is worth mentioning that since the fixing position of the crucible 3 is preset by the notch of the fixing table, it is possible to secure a uniform minimum distance from the heater 5 or the magnetic field coil at each position outside the metal sample 3 after the crucible 3 is fixed.

In this embodiment, the crucible 3, the heater 5 and the magnetic field coil are all set to the shape and size matched with the shape and size of the sample, so that the device can uniformly heat and melt from the thickness direction of the sample to the center of the sample, and the problem that when the existing device purifies a large-size metal sample, the heating and melting are not uniform due to the large thickness, and the purification is affected is avoided. In view of the above, the present embodiment also provides a corresponding limitation on the size of the sample according to the above arrangement, that is, the ratio of the width to the thickness of the sample is greater than or equal to 2, and the maximum thickness of the sample is less than or equal to 2 times of the height of the maximum melting region of the metal, wherein the cross-sectional shape of the sample is a flat plate shape, a cambered plate shape, a curved plate shape or a circular ring shape. When the sample is in a plate-shaped structure, the thickness of the embodiment refers to the length in the length, width and height of a conventional rectangular article, the width of the embodiment refers to the length in the length, width and height of the conventional rectangular article, and the height does not change; when the structure is a circular ring structure, the thickness refers to the thickness of the ring wall of the circular ring, the width refers to the diameter of the excircle of the circular ring, and the height does not change. When the sample adopts the shape structure, the purification of a large-size metal sample can be realized by matching with the corresponding structure of the device of the embodiment and the limitation on the size of the sample, which is an effect that the existing device cannot achieve, and the existing device can only purify a sample with a cylindrical structure with a small size generally. Meanwhile, by arranging the fixing mechanism corresponding to the shape and the size of the crucible 3, the large-size sample can be fixed accurately and quickly, the stable operation of purification is ensured, and the purification efficiency is improved.

In order to control the temperature of the heater 5 and the magnetic field of the magnetic field coil more precisely, the heater 5 of the present invention is connected with a heater controller 15 for setting the heating power of the heater 5. The motor 14 is connected to a motor controller for setting the operation power of the motor 14 and determining the speed of the rising or falling of the heater 5 and the field coil. The magnetic field coil is connected with a magnetic field power supply controller 16 outside the vacuum box body 1 and used for setting current parameters and determining the type and the strength of an introduced magnetic field.

In order to smoothly establish a vacuum environment in the vacuum chamber 1, a vacuum pump 11 is provided outside the vacuum chamber 1. The vacuum pump 11 is communicated with the vacuum box body 1 through the vacuum pipe 10, the vacuum pipe 10 is provided with a valve 23, and the valve 23 is closed to prevent the gas inside and outside the vacuum box body 1 from flowing through the vacuum pipe 10.

In order to moderate the gas pressure inside the vacuum chamber 1, or some metals need to be purified in a specific protective gas atmosphere, a protective gas tank 8 is also provided outside the vacuum chamber 1. The protective gas tank 8 is communicated with the vacuum box body 1 through the protective gas tank 7, the protective gas pipe 7 is provided with a gate valve and a gas pump, and protective gas in the protective gas tank 7 is pumped into the vacuum box body 1 through the gas pump.

In order to make the air pressure in the vacuum box body 1 consistent with the outside after the purification is finished, the box door of the vacuum box body 1 can be conveniently opened without being limited or influenced by the air pressure, more than one air release port 9 is further formed in the side wall of the vacuum box body 1, and a sealing plug is plugged in the air release port 9. After purification is finished, when the box door needs to be opened, the sealing plug is firstly opened, so that outside air enters the vacuum box body 1, and the air pressure inside and outside the vacuum box body 1 is balanced.

The following is a complete and clear description of how the purification apparatus can purify a metal sample.

Step 1: installing a sample: a solid metal sample is put into the crucible 3, the upper end of the crucible 3 is covered and sealed, the door of the vacuum box body 1 is opened, the height of the bottom fixing table 22 is lowered, the distance between the top fixing table 2 and the bottom fixing table 22 is larger than the height of the crucible 3, and the heater 5 is lowered to the lowest position. At this time, the lowermost end of the slider 17 abuts against the middle stopper 13. The bottom of the crucible 3 is firstly inserted into the groove of the bottom fixing table 22, then the fastening bolts on the two sides of the bottom fixing table are screwed to fix the sample, then the bottom fixing table 22 is lifted, the top of the crucible 3 is inserted into the groove of the top fixing table 2, then the fastening bolts 20 on the two sides of the top fixing table 2 are screwed to fix the crucible 3, and after all the crucibles 3 are sequentially installed and fixed, the door of the vacuum box body 1 is closed.

It should be noted that, in this step, in order to prevent the solidified sample from adhering to the inner wall of the crucible 3 and being difficult to take out, a layer of release agent may be coated on the inner wall of the crucible 3. Therefore, the present embodiment takes the following measures: in the initial preparation of the sample, the sample 3 is poured into a mold having a cavity slightly smaller than the cavity of the crucible 3 (the size difference is not greater than 1mm), the shape is kept uniform, and a mold release agent, graphite in this example, is coated on the inner side wall of the mold. When molten metal for preparing a sample is poured into a mold and then cooled, a layer of compact oxide film is formed on the surface of the solidified sample, so that when the prepared sample is placed into the containing cavity of the crucible 3 again, the shape of the sample is basically kept unchanged during purification and melting, the oxide layer can still be kept on the surface of molten metal, and the position of the oxide layer is basically kept unchanged after the metal is cooled, so that the separation effect is realized between the metal and the inner wall of the crucible 3, and the sample is conveniently taken out of the crucible.

Step 2: vacuumizing: and (3) opening the vacuum pump 11, opening a valve 23 on the vacuumizing pipe, sucking air in the vacuum box body 1 to enable the vacuum box body 1 to reach a preset vacuum degree, closing the valve on the vacuumizing pipe and closing the vacuum pump 10. And (4) if the metal needs to be purified in the protective gas environment, entering the step 3, otherwise, directly entering the step 4.

And step 3: and (3) protective gas filling: and (4) opening a gas pump on the protective gas pipe 7, then opening a gate valve on the protective gas pipe, filling protective gas into the vacuum box body 1 until the air pressure in the vacuum box body 1 reaches a desired value, and if the metal needs to be purified in a magnetic field environment, entering the step 4, otherwise, directly entering the step 5.

And 4, step 4: energizing a magnetic field coil: the field coil is energized by setting current parameters via the field power controller 16.

And 5: the heater 5 is electrified: the heater 5 is electrified until the heater reaches the purification temperature of the corresponding sample, the motor 14 is started, the motor 14 drives the screw rod 18 to rotate, the screw rod 18 drives the sliding block 17 to ascend along the screw rod 18 at a certain speed, the sliding block 17 drives the heater 5 to ascend on the screw rod 18, and the upper end magnetic field coil 4 and the lower end magnetic field coil 6 also ascend through the sliding block connected with the screw rod 18.

Step 6: and (3) purification: after the metal is heated and melted, the metal moves from the bottom to the top of the crucible 3 along with the heater 5 and the magnetic field coil and then moves from the top to the bottom, impurity elements are gathered and separated at the upper end and the lower end of the sample due to selective crystallization in the solidification process, and the circulation process is repeated.

And 7: air bleeding: the heater 5 is powered off, the magnetic field coil is powered off, after the heater 5 and the metal sample 3 are cooled to normal temperature, the sealing plug in the air release port 9 is opened, and air outside the vacuum box body 1 enters the vacuum box body 1 from the air release port until the air pressure inside and outside the vacuum box body 1 is consistent.

And 8: taking out a sample: the heater 5 is lowered to the lowest position, the door of the vacuum box body 1 is opened, the fixing bolt 20 at the top of the crucible 3 is loosened, and the top of the crucible 3 is separated from the groove of the top fixing table 2. Then, the bottom holding table 22 is lowered to the lowest position, the fastening bolts 20 on the bottom holding table 22 are loosened, the crucible 3 is gripped by the gripper, and the crucible 3 is opened to take out the sample therein from the crucible 3 by the gripper.

And step 9: cutting a sample: and cutting off preset parts at the upper end and the lower end of the sample 3, wherein the rest part is a purified product.

The examples described herein are merely illustrative of the preferred embodiments of the present invention and do not limit the spirit and scope of the present invention, and various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A metal purification device is characterized in that: the device comprises a vacuum box body (1), wherein the inside of the vacuum box body (1) is in a vacuum state, and a fixing mechanism, a crucible (3), a heater (5) and a lifting mechanism are arranged in the vacuum box body; the fixed establishment is used for fixed crucible (3), crucible (3) have and hold the chamber, the shape and the size that hold the chamber and wait to purify the shape and the size phase-match of metal sample, heater (5) encircle crucible (3) arrange and with the shape phase-match of crucible (3), elevating system is used for going up and down heater (5).

2. A metal purification apparatus as claimed in claim 1, wherein: the fixing mechanism comprises a top fixing table (2), a bottom fixing table (22) and a lifter (12); the top fixing table (2) is installed at the top of the vacuum box body (1), the lifter (12) is installed at the bottom of the vacuum box body (1), and the bottom fixing table (22) is installed on the lifter (12); the crucible (3) is fixed between the top fixing table (2) and the bottom fixing table (22).

3. A metal purification apparatus as claimed in claim 2, wherein: grooves matched with the shape of the crucible (3) are respectively formed in the lower end face of the top fixing table (2) and the upper end face of the bottom fixing table (22).

4. A metal purification apparatus as claimed in claim 3, wherein: and screw holes penetrating through the top fixing table (2) or the bottom fixing table (22) are formed in the top fixing table (2) or the bottom fixing table (22) on two sides of the groove, and fastening bolts (20) penetrate through the screw holes.

5. A metal purification apparatus as claimed in claim 1, wherein: the crucible heating device is characterized by further comprising two magnetic field coils, wherein the magnetic field coils are arranged around the crucible (3) and matched with the crucible (3) in shape, and the two magnetic field coils are an upper end magnetic field coil (4) located above the heater (5) and a lower end magnetic field coil (6) located below the heater (5).

6. A metal purification apparatus as claimed in claim 5, wherein: the lifting mechanism comprises a motor (14), a sliding block (17), a screw rod (18) and a bearing (19); the motor (14) is arranged outside the vacuum box body (1), the screw rod (18) is vertically arranged inside the vacuum box body (1), and the bearing (19) is fixed on the inner side wall of the vacuum box body (1); an output shaft of the motor (14) is in transmission connection with one end of a screw rod (18), and the other end of the screw rod (18) is connected with a bearing (19); the screw rod (19) is sleeved with a nut, the nut is fixedly connected with a nut seat, the sliding block (17) is fixedly connected with the nut seat, and the heater (5) and the magnetic field coil are fixedly connected with the sliding block (17).

7. A metal purification apparatus as claimed in claim 6, wherein: one side of the bottom fixing table (22) close to the screw rod (18) is provided with a middle limiting block (13), and the middle limiting block (13) is positioned under the sliding block (17).

8. A metal purification apparatus as claimed in any one of claims 1 to 7, wherein: the cross section of the metal sample to be purified is in a shape of a flat plate, a cambered plate, a curved plate or a circular ring.

9. A metal purification apparatus as claimed in any one of claims 1 to 7, wherein: the ratio of the width to the thickness of the sample is more than or equal to 2, and the maximum thickness of the sample is less than or equal to 2 times of the height of the maximum melting area of the metal.

10. A metal purification method using a metal purification apparatus according to any one of claims 1 to 9, characterized in that: the method comprises the following operation steps:

firstly, installing a sample: putting a sample into the crucible (3), and fixing the crucible (3) through a fixing mechanism;

secondly, vacuumizing: sucking air in the vacuum box body (1) to enable the interior of the vacuum box body (1) to reach a set vacuum degree;

thirdly, electrifying: electrifying the heater (5) to a set temperature, and electrifying the magnetic field coil to set parameters if the sample needs to be purified in a magnetic field environment;

fourthly, purification: the heater (5) and the magnetic field coil are controlled by the lifting mechanism to start to rise from the lower end of the crucible (3), then fall after reaching the upper end of the crucible (3), and the heater (5) and the magnetic field coil are repeatedly lifted until impurity elements are gathered and separated at the upper end and the lower end of the sample;

fifthly, taking out a sample: powering off the heater (5) and the magnetic field coil, enabling the internal and external air pressures of the vacuum box body (1) to be consistent after the sample is cooled, then opening the vacuum box body (1), enabling the fixing mechanism to loosen the crucible (3), and then taking out the sample;

sixthly, cutting a sample: cutting off the preset parts of the upper end and the lower end of the sample, wherein the rest part is the purified product.

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