A method and device for multi-layer droplet vacuum distillation

Abstract

A method and apparatus for multi-layer droplet vacuum distillation, comprising an upper cover, a furnace body, and a distillation chamber formed by the upper cover and the furnace body; a feed pipe is mounted on the upper cover, and a vacuum displacement chamber is provided on the feed pipe; a condensation outlet is provided on the furnace body, a discharge port is provided at the bottom of the furnace body, and a plurality of heating wires are provided within the furnace wall; the distillation chamber is provided with a plurality of layers of porous trays mounted on the furnace body, and a plurality of holes are distributed on the bottom surface of the porous trays. The method mainly comprises the following steps: loading - solution droplet droplet droplet droplet droplet droplet droplet droplet polymerization - repeated distillation - purified solution collection. The present invention increases the proportion of atomized droplets, increases the droplet gas-liquid interface, and prolongs the duration of the droplet atomization state by providing a plurality of layers of porous trays, thereby improving the distillation efficiency of the device.

Description

Technical Field

[0001] The present invention relates to the field of metal purification, and in particular to a method and a device for multi-layer dripping vacuum distillation. Background Art

[0002] Metals primarily exist in nature as minerals. Purification of these minerals is necessary to obtain metallic elements. However, minerals contain a variety of impurities in addition to metallic elements. Therefore, the metal materials obtained after mineral purification often contain a variety of impurities. The presence of these impurities can severely impact the intrinsic properties and performance of the metal. Therefore, the more thoroughly impurity elements are removed, the higher the purity of the metal and the greater its application value.

[0003] Vacuum distillation is a commonly used metal purification method. It separates low-boiling-point elements by exploiting the differences in their saturated vapor pressures at specific temperatures and vacuum levels. The temperature and vacuum level for each element during distillation are relatively fixed values, and elements with adjacent higher saturated vapor pressures have a correlation with temperature. Therefore, the vacuum distillation temperature and vacuum level for a specific element fall within a relatively clear range. However, controlling the vacuum distillation process primarily relies on time, leading to high energy consumption and low efficiency.

[0004] Later, people found that the gas-liquid interface area of ​​the solution had a significant impact on the distillation rate during vacuum distillation. The gas-liquid interface area of ​​the solution could be used as the main factor in regulating the distillation rate. Based on this, people made various attempts:

[0005] In the patent document with the authorization announcement number CN206345893U and the authorization announcement date of 2017.07.21, the subject title is "A high-purity metal vacuum distillation device", which discloses a method of enhancing the distillation rate by mechanically stirring the metal solution to continuously replace the liquid-solid interface. This method partially improves the outward diffusion of low-melting-point elements in the solution, but the proportion of the atomized liquid is small and the effect is limited.

[0006] Research by Xi'an Jiaotong University found that in the patent document with application publication number CN113621823A and application publication date 2021.11.09, the subject name is "A method and device for preparing high-purity metals or alloys by an efficient distillation method", a one-time atomization method using centrifugal atomization to enhance the gas-liquid interface is disclosed. This method is suitable for the separation of elements with low boiling point and high saturated vapor pressure (magnesium and calcium, etc.), and can achieve 100% atomization of the solution, significantly increasing the gas-liquid interface area of ​​the solution, but the droplet atomization state lasts for a short time; in the patent document with authorized patent announcement number CN215975977U and authorization announcement date 2022.03.08, the subject name is "A device for in-situ atomization of flying liquid paddles to enhance the distillation of metals or alloys", the flying slurry atomization technology is disclosed. This method prolongs the liquid atomization time and increases the distillation volume by multiple atomization of the metal solution. This technology can be atomized multiple times, but the droplet atomization state lasts for a short time, and the atomized liquid volume of the solution accounts for about 10-20%, which is relatively low and more suitable for the separation of elements with low distillation efficiency.

[0007] Therefore, the existing technologies provided by the above three patent documents have the problems of small gas-liquid interface area, short duration of droplet atomization state, and low proportion of atomized droplets of the solution. These problems lead to low distillation efficiency of vacuum distillation, and the above technologies all require the introduction of external power (stirring or atomizing the solution through mechanical transmission to enhance the gas-liquid interface area). The introduction of external power will not only increase the power consumption of the equipment and bring about high energy consumption problems, but also affect the vacuum degree of the distillation process due to the dynamic sealing structure, thereby affecting the distillation efficiency.

[0008] To sum up, in addition to the influence of vacuum degree and temperature, the key to improving distillation efficiency is to achieve a larger proportion of atomized droplets, a larger droplet gas-liquid interface and a longer droplet atomization state duration. To continue to improve the efficiency of vacuum distillation based on existing technology, in addition to increasing the gas-liquid interface area of ​​the solution, it is also necessary to consider how to achieve a higher solution atomization liquid proportion and a longer droplet atomization state duration. Summary of the Invention

[0009] The purpose of the present invention is to overcome the problems of high energy consumption and low distillation efficiency in the prior art and provide a method and apparatus for multi-layer droplet vacuum distillation with low energy consumption and high distillation efficiency.

[0010] The device of the present invention includes an upper cover, a furnace body and a distillation chamber formed by the upper cover and the furnace body; a feed pipe with a vacuum replacement chamber is installed on the upper cover; a condensation outlet connected to a condensation device is opened at the upper end of the side wall of the furnace body, a discharge port is opened at the bottom of the furnace body, and a heating wire is arranged in the furnace wall of the furnace body; and a plurality of layers of porous trays with gaps between the tray and the furnace wall are arranged in the distillation chamber.

[0011] The porous tray is a D-shaped structure.

[0012] The discharge port is connected to a collecting device.

[0013] A thermocouple is installed on the upper cover.

[0014] The upper cover is provided with an air outlet.

[0015] The furnace wall is composed of an inner lining, a thermal insulation layer and an outer lining from the inside to the outside, and a heating wire is arranged in the thermal insulation layer.

[0016] An air inlet or vacuum port is provided on the furnace wall.

[0017] The upper cover is detachably covered on the top of the furnace body.

[0018] The inlet and outlet of the vacuum replacement chamber are both equipped with a feed valve and a discharge valve.

[0019] The method for performing multi-layer dripping vacuum distillation based on the above device comprises the following steps:

[0020] 1) Loading

[0021] Open the feed valve, close the discharge valve, and vacuum or replace the air in the vacuum replacement chamber. After completion, open the discharge valve and gradually put the raw materials in. The primary purity metal on the porous tray in the distillation chamber melts to form a metal solution.

[0022] 2) Solution dropletization

[0023] The metal solution falls freely under the action of gravity and forms several droplets after passing through several holes in the porous tray;

[0024] 3) Distillation

[0025] Distillation of low-boiling-point elements occurs at the gas-liquid interface of the solution and droplets;

[0026] 4) Droplet polymerization

[0027] Several droplets passing through the holes will experience a short period of free fall and efficient distillation, and then fall in the next layer of porous tray in an "impact" manner to force mixing;

[0028] 5) Repeated distillation

[0029] The droplets and liquid repeat steps 2)-5) between the following multi-layer porous trays;

[0030] 6) Collection of purified solution

[0031] The high-purity metal solution that has completed the above distillation process is dripped and rectified through the last layer of porous tray and then flows out from the discharge port.

[0032] The beneficial effects of the present invention are:

[0033] (1) The device and method provided by the present invention can realize multiple liquefaction of metal droplets without introducing external power, so the device does not need a dynamic sealing structure, the vacuum degree of the device is high; and when no external force stirring or atomization is required, the energy consumption is low.

[0034] (2) The device and method provided by the present invention increase the proportion of atomized droplets, increase the droplet gas-liquid interface, and prolong the duration of the droplet atomization state by setting up several layers of porous trays, thereby improving the distillation efficiency of the device. Because at the same height, multi-layer dropletization can allow the metal solution to be repeatedly distilled, and the process of "solution dropletization-distillation-droplet polymerization" is continuously circulated, which can achieve efficient atomization and dropletization without the introduction of external power; and when the droplets are in free fall at a certain height, the number of droplets in the multi-layer drip flow and the time they stay in the air are much higher than those in the single drip flow state; and this setting can also increase the proportion of atomized liquid and increase the atomized gas-liquid interface area. In addition, the number, size and speed of droplets in the multi-layer drip flow process can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall structure of the heating furnace device;

[0036] Figure 2 It is a schematic diagram of the partial enlarged structure of the furnace wall in the device;

[0037] Figure 3 is a top view of the porous tray in the device;

[0038] Figure 4 is a side cross-sectional view of a perforated tray.

[0039] In the figure, 1-heating furnace device, 2-condensing device, 3-vacuum replacement chamber, 4-porous tray, 41-hole, 5-collecting device, 6-thermocouple, 7-upper cover, 8-furnace body, 11-distillation chamber, 12-furnace wall, 121-inner lining, 122-insulation layer, 123-heating wire, 124-outer lining, 13-air inlet or vacuum port, 14-condensation outlet, 15-feed pipe, 16-air outlet, 17-discharge port. Specific embodiments

[0040] The structural principle and working principle of the present invention are further explained below with reference to the accompanying drawings and embodiments.

[0041] like Figure 1As shown, the heating furnace apparatus 1 provided by the present invention includes an upper cover 7, a furnace body 8, and a distillation chamber 11 formed by the upper cover 7 and the furnace body 8. The upper cover 7 is removably attached to the top of the furnace body 8 to facilitate placement of primary purity metal, while the distillation chamber 11 provides a distillation space for the primary purity metal. The upper cover 7 is provided with an air outlet 16 to discharge exhaust gases generated during the reaction process. The upper cover 7 is also equipped with a thermocouple 6 for detecting the temperature within the distillation chamber 11 (to assist in the startup and shutdown of the heating furnace apparatus 1), as well as a feed pipe 15 for a vacuum chamber 3. The inlet and outlet of the vacuum chamber 3 are both equipped with feed and discharge valves. The added raw materials are evacuated or replaced with air through the vacuum chamber 3. The furnace body 8 is provided with an air inlet or vacuum port 13 and a condensation outlet 14 connected to the condensation device 2. The air inlet or vacuum port 13 is used for evacuation and replenishment of inert gas, and the condensation outlet 14 is used to discharge the distilled gaseous metal, thereby achieving metal purification. The bottom of the furnace body 8 is provided with a discharge port 17 connected to the collection device 5. The distillation chamber 11 is provided with several layers of D-shaped porous trays 4 mounted on the furnace body 8, such as Figure 3 、 Figure 4 As shown, a plurality of holes 41 are distributed on the bottom surface of the porous tray 4 .

[0042] like Figure 2 As shown, the furnace wall 12 of the furnace body 8 is composed of an inner lining 121, an insulating layer 122, and an outer lining 124 from the inside to the outside. A heating wire 123 is provided in the insulating layer 122, which can heat the primary purity metal or alloy to a molten state.

[0043] The method for carrying out multi-layer dripping vacuum distillation with the above-mentioned apparatus comprises the following steps:

[0044] 1) Loading

[0045] Open the feed valve, close the discharge valve, and vacuum or replace the air in the vacuum replacement chamber (3). After completion, open the discharge valve and gradually put the raw materials down. This process can ensure the vacuum degree or atmosphere environment of the distillation chamber 11. As the temperature in the distillation chamber 11 increases, the primary purity metal on the porous tray 4 melts to form metal liquid.

[0046] 2) Solution dropletization

[0047] The metal solution falls freely under the action of gravity and forms a number of droplets after passing through the multiple holes 41 of the porous tray 4. The size of the droplets is determined by the diameter of the porous tray 4 and the viscosity of the solution. The number of droplets is determined by the number of holes 41 of the porous tray 4. The falling speed of the droplets is determined by parameters such as the diameter of the hole 41, the viscosity of the liquid, and the layer height between the upper and lower trays.

[0048] 3) Distillation

[0049] Distillation of low-boiling-point elements occurs at the gas-liquid interface of the solution and the droplets; the distillation efficiency is related to the total area of ​​the liquid-gas-liquid interface, which includes the surface area of ​​all droplets and the surface area of ​​the solution in the tray.

[0050] 4) Droplet polymerization

[0051] Several droplets passing through the hole 41 will experience a short period of free fall and efficient distillation. After this process, the concentration of volatile elements on the droplet surface decreases and the distillation efficiency decreases. At this time, several droplets fall in an "impact" manner into the next layer of porous tray 4 and are forced to mix. At this time, the distilled elements inside the solution will become relatively uniform, enhancing the diffusion rate in the droplets during the next distillation.

[0052] 5) Repeated distillation

[0053] The droplets and liquid repeat steps 2) to 5) between the following 4 multi-layer porous trays to achieve multiple efficient distillations.

[0054] 6) Collection of purified solution

[0055] After the high-purity metal solution has completed the above distillation process, it is rectified by the last layer of porous tray 4 and flows out from the discharge port 17. It can directly enter the mold and form a product of a certain shape after cooling.

[0056] The working principle of the present invention is: by arranging several layers of porous trays 4 in the distillation chamber 11, the triple effects of increasing the proportion of atomized droplets, extending the duration of the droplet atomization state, and increasing the atomized gas-liquid interface area are achieved without external power conditions.

[0057] (1) Prolonging the duration of the droplet atomization state: When droplets fall freely at the same height, dividing the height into multiple layers can prolong the time the droplets stay in the air. The following is a specific example to illustrate this principle: Assuming that a droplet falls freely under the action of gravity, the time it takes for the droplet to drip from a height of 1.0m is 0.144s. If the height of 1.0m is divided into 10 layers, each layer is 0.1m high, the time it takes for the droplet to drip from the 1.0m height divided into 10 layers is 0.456s, and the time the droplet stays in the air is increased by 3.17 (0.456 / 0.144=3.17) times. In other words, if the same number and volume of droplets fall simultaneously in each layer, after the height is divided into 10 layers, the time the droplets stay in the air can be extended by 3.17 times, which has a very significant effect on the distillation rate.

[0058] (2) Increase the proportion of atomized liquid: The proportion of atomized liquid is the ratio of the total amount of liquid that exists in the form of droplets to the total amount of liquid. The higher the ratio, the greater the proportion of atomized liquid. Atomized liquid volume = number of micropores per disk × number of disks. The more layers, the greater the atomized liquid volume.

[0059] (3) Increase the gas-liquid interface area: The total gas-liquid interface area of ​​the liquid includes the surface area of ​​all droplets and the surface area of ​​the liquid in the tray. The surface area of ​​the liquid in the tray = the area of ​​a single tray × the number of layers. The higher the number of layers, the larger the surface area of ​​the liquid in the tray. Similarly, the surface area of ​​the droplet = the area of ​​a single droplet × the amount of atomized liquid = the area of ​​a single droplet × the number of micropores in a single tray × the number of trays. As the number of trays and the number of micropores in a single tray increase, the droplet surface area increases. It can be seen that as the number of tray layers increases, the gas-liquid interface area of ​​the distilled liquid increases significantly.

[0060] The device provided by the present invention can be used for both removing low-boiling-point impurities and purifying low-boiling-point metals; it can be used under both vacuum and gas shielding conditions. The device provided by the present invention is not only highly efficient and energy-efficient, but also, through a "space capsule" approach, enables continuous distillation and large-scale production. Metals purified by the device provided by the present invention can be molded or pelletized online, thus having a wide range of applications.

Claims

1. A multi-layer droplet vacuum distillation apparatus, characterized in that: The invention comprises an upper cover (7), a furnace body (8) and a distillation chamber (11) formed by the upper cover (7) and the furnace body (8); a feed pipe (15) with a vacuum replacement chamber (3) is installed on the upper cover (7); a condensation outlet (14) connected to a condensation device 2 is provided at the upper end of the side wall of the furnace body (8), a discharge port (17) is provided at the bottom of the furnace body (8), and a heating wire (123) is provided in the furnace wall (12) of the furnace body (8); and a plurality of layers of porous trays (4) with gaps between the tray and the furnace wall are provided in the distillation chamber (11).

2. A multi-layer droplet vacuum distillation apparatus according to claim 1, characterized in that: The porous tray (4) is a D-shaped structure.

3. A multi-layer dripping vacuum distillation apparatus according to claim 1, characterized in that: The discharge port (17) is connected to the collecting device (5).

4. A multi-layer dripping vacuum distillation apparatus according to claim 1, characterized in that: A thermocouple (6) is installed on the upper cover (7).

5. A multi-layer dripping vacuum distillation apparatus according to claim 1, characterized in that: The upper cover (7) is provided with an air outlet (16).

6. A multi-layer dripping vacuum distillation apparatus according to claim 1, characterized in that: The furnace wall (12) is composed of an inner lining (121), a heat-insulating layer (122), and an outer lining (124) from the inside to the outside, and a heating wire (123) is arranged in the heat-insulating layer (122).

7. The multi-layer droplet vacuum distillation apparatus according to claim 1, characterized in that: An air inlet or vacuum port (13) is provided on the furnace wall (12).

8. The multi-layer droplet vacuum distillation apparatus according to claim 1, characterized in that: The upper cover (7) is detachably covered on the top of the furnace body (8).

9. The multi-layer dripping vacuum distillation apparatus according to claim 1, characterized in that: The inlet and outlet of the vacuum replacement chamber (3) are both equipped with a feed valve and a discharge valve.

10. A method for multi-layer droplet vacuum distillation using the apparatus according to any one of claims 1 to 9, characterized in that: The following steps are involved: 1) Loading Open the feed valve, close the discharge valve, and vacuum or replace the air in the vacuum replacement chamber (3). After completion, open the discharge valve and gradually put the raw materials in. The primary purity metal on the porous tray (4) in the distillation chamber (11) melts to form a metal solution; 2) Solution dropletization The metal solution falls freely under the action of gravity and forms a plurality of metal droplets after passing through a plurality of holes (41) of the porous tray (4); 3) Distillation Distillation of low-boiling-point elements occurs at the gas-liquid interface of the metal solution and metal droplets; 4) Droplet polymerization The metal droplets passing through the hole (41) will experience a short period of free fall and efficient distillation, and then fall in the next layer of porous tray (4) in an "impact" manner to be forced to mix; 5) Repeated distillation The metal droplets and the metal solution repeat steps 2) to 5) between the next-level multi-layer porous tray (4); 6) Collection of purified solution The high-purity metal solution that has completed the above-mentioned distillation process is dripped and rectified through the last layer of porous tray (4) and then flows out from the discharge port (17).

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