APPARATUS AND METHOD FOR PREPARING HIGH-PURITY SPHERICAL MAGNESIUM AND/OR HIGH-PURITY MAGNESIUM POWDER

Abstract

An apparatus and method for preparing high-purity spherical magnesium and/or high-purity magnesium powder are provided. The apparatus includes a vertical furnace body, a heating zone, and a condensing zone, where a periphery of the condensing zone is provided with a first thermal insulation device and a second thermal insulation device sequentially from bottom to top, and each of the first thermal insulation device and the second thermal insulation device is removably arranged; the periphery of the condensing zone is further provided with a liquid cooling device; a gas inlet and a gas outlet are formed in the condensing zone; and an inner wall of the condensing zone is provided with an arrangement structure configured to arrange a collection device. A heating temperature of a material and condensation conditions in the condensing zone are controlled to make an evaporated magnesium vapor condensed on the collection device in the condensing zone.

Description

CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is a continuation application of International Application No. PCT/CN2023/082066, filed on Mar. 17, 2023, which is based upon and claims priority to Chinese Patent Application No. 202211022901.1, filed on Aug. 25, 2022, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to the technical field of preparation of high-purity metal materials, and in particular relates to an apparatus and method for preparing high-purity spherical magnesium and/or a high-purity magnesium powder.

BACKGROUND

Magnesium is widely used in fields such as automobiles, aerospace, rail transit, electronic communications, national defense and military industry due to its advantages such as high specific strength, high specific stiffness, easy forming, excellent damping and shock absorption, and strong electromagnetic shielding ability, so, it is considered as green engineering material in the 21st century. Magnesium is also be recognized as a revolutionary medical metal material due to its excellent biocompatibility and biodegradability. In addition, magnesium is used in steel desulfurization and as a strategic metallic reducing agent due to its active chemical properties. Spherical magnesium and magnesium powder have a large specific surface area (SSA) and a strong surface activity, so, spherical magnesium and magnesium powder can be used for producing chemical products, explosives, fireworks, or the like and can also be used as efficient reducing agents, desulfurizing agents, and 3D printing raw materials. Besides, magnesium powder can also be used in high-tech fields such as exclusive magnesium powder pigments for automobile and building industries and conductive pastes for solar photovoltaic (PV) cell back sheets.

In China, magnesium resource are very abundant, magnesium ingot output has ranked first in the world for many years, and after recent decades of development, great progress has been made in the research on applications of magnesium in fields such as alloy production, hydrogen storage materials, and medical materials. However, the research on preparation of magnesium powder started late and developed slowly in China. Currently, methods for producing magnesium powder mainly include atomization method, cutting method, and ball-milling method, and the like. The above methods have defects such as complicated devices, large noises, unstable product sizes, low production efficiency, and low product purity. Research on preparation of spherical magnesium is rarely reported. Therefore, it is of great significance to develop a simple and efficient method for preparation of high-purity spherical magnesium and high-purity magnesium powder.

The patent 201710726429.2 provides a method for preparing high-purity magnesium powder, which indicated that: sublimation and condensation of raw materials in a tubular furnace at 700-1500° C. (preferably 1,000-1,300° C.) can prepare high purity magnesium powder with a purity of 99.9%, however, this method is suitable for a small scale production and the purity of the product is limited. The patent 201310082862.9 provides a method for producing high-purity fine spherical magnesium powder based on pneumatic atomization, the spherical magnesium powder is prepared through argon atomization and nitrogen cooling. But this method requires the use of nitrogen and argon, the cooling and separation devices are expensive and the process is complex.

The patent 202011059832.2 discloses a device and method for producing spheroidic magnesium powder, near spherical magnesium particles are prepared through cutting magnesium ingot. However, this method cannot guarantee a uniform particle size of the magnesium powder, and has disadvantages such as complicated devices, large noises, and unstable product particle sizes.

The patent 202111623596.7 discloses a device and method for preparing high-purity ultra-fine spherical magnesium powder, this method includes: 120 g magnesium ingot was heated for 40 min, and then under the combined action of evaporative furnace, particle condenser, cyclone dust collector, gas filter, and gas cooler, magnesium powder with purity of 99.9% was obtained. However, this method is suitable for small scale production and has a low product purity.

In summary, the existing methods have technical problems such as unavailable large-scale production, low product purity, complicated devices, and complicated processes.

SUMMARY

The present disclosure provides an apparatus and method for preparing high-purity spherical magnesium and/or a high-purity magnesium powder to solve at least one of the problems such as small preparation scale, low product purity, and complicated process and device faced by the methods for preparing high-purity spherical magnesium and a high-purity magnesium powder in the prior art.

In the first aspect, the present disclosure provides an apparatus for preparing high-purity spherical magnesium and/or high-purity magnesium powder, the apparatus including a vertical furnace body which has a heating zone and a condensing zone, where the heating zone and the condensing zone are arranged in the vertical furnace body, and the heating zone is located below the condensing zone; a heating unit is arranged around the heating zone; a first thermal insulation device and a second thermal insulation device are arranged successively from the bottom to the top at the periphery of the condensing zone, and each of the first thermal insulation device and the second thermal insulation device can be disassembled or installed respectively; the periphery of the condensing zone is further provided with a liquid cooling device; a gas inlet and a gas outlet are formed in the condensing zone; and the inner wall of the condensing zone is provided with an arrangement structure configured to arrange a collection device.

Further, the apparatus further includes a filtering device removably arranged between the heating zone and the condensing zone.

Further, the apparatus further includes a plurality of collection devices, where the width of each collection device is greater than a half of the diameter of the vertical furnace body and smaller than the diameter of the vertical furnace body, and the plurality of collection devices are staggered on the inner wall of the condensing zone.

Further, the condensing zone includes a cooling liquid inlet, a cooling liquid outlet, and a cooling pipeline; the cooling liquid outlet is arranged at the top of a side wall surface of the vertical furnace body corresponding to the condensing zone; the cooling pipeline is coiled on an outer wall surface of the heating zone and/or the condensing zone; and the cooling liquid inlet is arranged at the bottom of a side wall surface of the vertical furnace body corresponding to the heating zone or the condensing zone.

Further, the apparatus further includes: a vacuum pump and a gas storage device, where the vacuum pump is connected to the gas outlet through a pipeline and a first control valve, and the gas storage device is connected to the gas inlet through a pipeline, a second control valve, and a flow meter.

Further, the apparatus further includes a control system, where the control system includes a heating control system, a gas control system, and a cooling liquid-circulation system; the heating control system is connected to the heating unit and temperature sensors which are respectively arranged in the heating zone and the condensing zone; the gas control system is connected to the vacuum pump, the first control valve, the second control valve, and the flow meter; and the cooling liquid-circulation system is connected to a liquid pump configured to make a cooling liquid circularly flow in the liquid cooling device.

Further, the apparatus further includes a crucible arranged in the heating zone.

In a second aspect, the present disclosure provides a method for preparing high-purity spherical magnesium and/or a high-purity magnesium powder with the apparatus for preparing high-purity spherical magnesium and/or a high-purity magnesium powder described above, including the following steps:

• • S10. Adding crude magnesium or magnesium ingot to the crucible, placing the crucible in the heating zone, arranging the filtering device and the plurality of collection devices above the crucible sequentially, and sealing the vertical furnace body;
  • S20. Turning on the vacuum pump and the first control valve to allow vacuuming; when the vacuum degree in the vertical furnace body reaches the preset vacuum degree, starting to heat the heating zone, and turning on both the second control valve and the cooling liquid-circulation system to make a gas and a cooling liquid flow, where the gas is a gas that does not react with a magnesium vapor;
  • controlling a temperature of the heating zone at 650° C. to 1,500° C., adjusting a gas flow rate by the second control valve to 1 LPM to 500 LPM, adjusting a cooling liquid flow rate to 1 LPM to 100 LPM, and controlling a temperature of the condensing zone at 100° C. to 700° C.;
  • S30. When the crude magnesium or the magnesium ingot evaporates completely, stopping heating; and when the temperature in furnace drops to room temperature, turning off the gas control system and the cooling liquid-circulation system, and taking the plurality of collection devices out to collect the high-purity spherical magnesium and/or the high-purity magnesium powder.

Further, when the temperature of the heating zone is controlled at 650° C. to 900° C., the gas flow rate is adjusted by the second control valve to 200 LPM to 500 LPM, the cooling liquid flow rate is adjusted to 50 LPM to 100 LPM, and the temperature of the condensing zone is controlled at 100° C. to 400° C., the high-purity magnesium powder alone is obtained; when the temperature of the heating zone is controlled at 900° C. to 1,500° C., the gas flow rate is adjusted by the second control valve to 1 LPM to 200 LPM, the cooling liquid flow rate is adjusted to 1 LPM to 50 LPM, and the temperature of the condensing zone is controlled at 400° C. to 700° C., the high-purity spherical magnesium alone is obtained; and when the temperature of the heating zone is controlled at 800° C. to 1,300° C. and preferably 900° C. to 1,200° C., the gas flow rate is controlled at 100 LPM to 400 LPM and preferably 200 LPM and 300 LPM, the cooling liquid flow rate is controlled at 30 LPM to 70 LPM and preferably 40 LPM to 60 LPM, and a temperature of a condensate is controlled at 200° C. to 600° C., both the high-purity spherical magnesium and the high-purity magnesium powder are obtained.

Further, when preparing high purity magnesium powder alone, the first thermal insulation device and the second thermal insulation device are removed; when the high-purity spherical magnesium alone is prepared, the first thermal insulation device and the second thermal insulation device are arranged; and when both the high-purity spherical magnesium and the high-purity magnesium powder are prepared, the first thermal insulation device is arranged, and the second thermal insulation device is removed.

Compared with the prior art, the apparatus and method for preparing high-purity spherical magnesium and/or a high-purity magnesium powder provided in the present disclosure at least have the following beneficial effects:

• • (1) In the apparatus of the present disclosure, raw material evaporation, metal vapor filtration and purification, metal vapor condensation, and product collection devices are effectively integrated into a vertical furnace body, and through the efficient cooperation of the these devices, the raw material purification and product preparation processes are implemented in one apparatus, which solves the problem that the existing apparatus systems are complicated, have a high production cost and low product purity.
  • (2) In the apparatus of the present disclosure, the first and second thermal insulation devices are detachable arranged respectively, the first and second thermal insulation devices can cooperate with a liquid cooling device and a cooling gas to flexibly control the temperature in condensing zone and effectively control the temperature distribution and temperature gradient in the apparatus, which avoids the problem that the two-stage heating temperature-control commonly used in the conventional apparatus results in apparatus complexity and increased energy consumption. With the apparatus of the present disclosure, two types of products can be prepared in batches or simultaneously in the same apparatus; and high-purity spherical magnesium and high-purity magnesium powders of different particle sizes can be obtained in a same batch, and then products of different specifications can be separated through sieving, which allows the production of diversified products in the same apparatus.
  • (3) In the method of the present disclosure, according to the principles such as different saturation vapor pressures of elements in crude magnesium or a magnesium ingot, magnesium vapor volatilization and condensation, molecular collision, and metal vapor nucleation crystallization, based on the apparatus design and condition control, the magnesium is purified through vacuum distillation and filtration, and different products are obtained by controlling condensation conditions, the product of the present disclosure has a purity of 99.999%, which can meet the use requirements in different fields. Therefore, the method of the present disclosure avoids the disadvantages such as small preparation scale, low product purity, and complicated process and apparatus in existing method. The cooling liquid and gas used in the present disclosure can be recycled, which meets the requirements of green and sustainable development in metallurgical and material industries.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the present disclosure clearly, the accompanying drawings required for describing the embodiments of the present disclosure or the prior art are briefly introduced below. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and persons of ordinary skill in the art may still derive other accompanying drawings from these accompanying drawings without creative efforts.

FIG. 1 is a schematic structural diagram of the device for preparing high-purity spherical magnesium and/or a high-purity magnesium powder in Example 1 of the present disclosure;

FIGS. 2A-2D show scanning electron microscopy (SEM) images of high-purity spherical magnesium and high-purity magnesium powder prepared in an embodiment of the present disclosure.

In FIG. 1, 1: control system; 2: vacuum pump; 3: vertical furnace body; 4: collection device; 5: top cover; 6: second thermal insulation device; 7: cooling liquid outlet; 8: first thermal insulation device; 9: gas storage device; 10: flow meter; 11: raw material, 12: crucible, 13: heating unit; 14: cooling liquid inlet; and 15: filtering device.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following description provides many different embodiments or examples for implementing different features of the present disclosure. The elements and arrangements described in the following specific examples are only intended to concisely express the present disclosure, and are only for illustration purposes, rather than for limiting the present disclosure.

Example 1

As shown in FIG. 1, an apparatus for preparing high-purity spherical magnesium and/or a high-purity magnesium powder is provided, including vertical furnace body 3, a heating zone, and a condensing zone, where the heating zone and the condensing zone are arranged in the vertical furnace body 3, and the heating zone is located below the condensing zone;

• • the periphery of the heating zone is arranged with heating unit 13; first thermal insulation device 8 and second thermal insulation device 6 are arranged at the outside of the condensing zone from bottom to top, and each of the first thermal insulation device 8 and the second thermal insulation device 6 is removably arranged; the periphery of the condensing zone is further provided with a liquid cooling device; a gas inlet and a gas outlet are formed in the condensing zone; and an inner wall of the condensing zone is provided with an arrangement structure configured to arrange a collection device.

The first thermal insulation device and the second thermal insulation device can be removable high temperature-resistant and thermal insulating material such as a graphite felt or thermally-insulating cotton, and are each directly wrapped around the periphery of the condensing zone. According to whether high-purity spherical magnesium or high-purity magnesium powder is prepared, the first thermal insulation device and/or the second thermal insulation device are/or selectively arranged. For example, when high-purity magnesium powder needs to be prepared, the first thermal insulation device and the second thermal insulation device are removed, a circulating cooling effect of cooling liquid in the liquid cooling device is enhanced, and an inert gas flow rate is controlled at a relatively-high level, such that the temperature of the condensing zone is controlled at 100° C. to 400° C. When high-purity spherical magnesium needs to be prepared, the first thermal insulation device and the second thermal insulation device are arranged, and a cooling liquid flow rate and an inert gas flow rate are both controlled at relatively-low levels, such that a temperature of the condensing zone is controlled at 400° C. to 700° C. When high-purity spherical magnesium and a high-purity magnesium powder need to be prepared simultaneously, the first thermal insulation device is arranged, and the second thermal insulation device is removed, such that a temperature of the condensing zone is controlled at 200° C. to 600° C.

The liquid cooling device on the periphery of the condensing zone is configured to make the cooling liquid flow through the periphery of the condensing zone, and is generally wound on an outer wall of the condensing zone in a form of pipeline, the manner of the winding may be spiral winding or other conventional winding, they are all conventional technologies in this field, which will not be repeated here. The cooling liquid can be selected according to specific situation, such as water or other types of cooling liquids in the art, they are all conventional technologies in this field, which will not be repeated here.

The condensing zone includes cooling liquid inlet 14, cooling liquid outlet 7, and cooling pipeline; the cooling liquid outlet is formed at a top of a side wall surface of the vertical furnace body corresponding to the condensing zone; the cooling pipeline is coiled on the outer wall surface of the heating zone and/or the condensing zone; and the cooling liquid inlet is formed at the bottom of another side wall surface of the vertical furnace body corresponding to the heating zone or the condensing zone. The cooling liquid includes, but is not limited to, cooling water, cooling oil, and other cooling media that can cool the furnace body.

It should be noted that the cooling pipeline can only be coiled on the periphery of the condensing zone and only cool the condensing zone, in which case the cooling liquid inlet is arranged at the bottom of the side wall surface of the vertical furnace body corresponding to the condensing zone; and the cooling pipeline can also be coiled on the peripheries of both the condensing zone and the heating zone and thus can cool both the condensing zone and the heating zone during production, that is, there is no need to additionally provide a separate cooling device to cool the heating zone and the entire apparatus can be easily cooled after experiment, in which case the cooling liquid inlet can be arranged at the bottom of a side wall surface of the vertical furnace body corresponding to the heating zone.

In an experiment, the liquid cooling device is connected to a liquid pump, and the cooling liquid is pumped by the liquid pump into the liquid cooling device, such that the cooling liquid flows on an outer wall surface of the condensing zone to take away heat inside the condensing zone; and in order to control the cooling liquid flow rate, a corresponding valve and a flow meter are further arranged.

The gas inlet and the gas outlet in the condensing zone are preferably arranged as follows: the gas inlet is formed at a bottom of one side wall surface of the vertical furnace body corresponding to the condensing area, and the gas outlet is formed at a top of the other side wall surface of the vertical furnace body corresponding to the condensing zone, such that the gas can pass through the entire condensing zone from bottom to top to allow an optimal effect, which not only ensures that the volatilized magnesium vapor can be fully in contact with the low-temperature gas, but also makes a magnesium vapor be carried to the collection device in the condensing zone under a synergistic effect of the gas flow and the pumping force of the vacuum pump.

In experiment, vacuum pump 2 and gas storage device 9 are further provided, where the vacuum pump 2 is connected to the gas outlet through a pipeline and a first control valve, and the gas storage device 9 is connected to the gas inlet through a pipeline, a second control valve, and flow meter 10. The pumping speed and flow rate of the vacuum pump are controlled by the first control valve, and the speed and flow rate of introduced gas are controlled by the second control valve. The gas introduced into the condensing zone is a gas that does not react with magnesium, including, but not limited to, an inert gas such as helium, neon, argon, krypton, xenon, and radon.

The apparatus further includes a filtering device removably arranged between the heating zone and the condensing zone. The filtering device can be a porous material made of graphite, ceramic, or metals, and the filtering device can effectively filter ash and large-particle impurities in a raw material out to improve purity of the prepared high-purity spherical magnesium and/or high-purity magnesium powder.

The apparatus further includes plurality of collection devices 4, where the width of each collection device is greater than a half of the diameter of the vertical furnace body and smaller than the diameter of the vertical furnace body; the plurality of collection devices are staggered on the inner wall of the condensing zone; and the plurality of collection devices can each be round graphite or stainless steel tower tray. The collection devices are configured to collect the prepared high-purity spherical magnesium and/or high-purity magnesium powder.

The apparatus further includes crucible 12 arranged in the heating zone. Those skilled in the art can understand that the crucible is configured to hold raw material 11.

The apparatus further includes control system 1, where the control system includes a heating control system, a gas control system, and a cooling liquid-circulation system; the heating control system is connected to the heating unit and temperature sensors respectively arranged in the heating zone and the condensing zone; the gas control system is connected to the vacuum pump, the first control valve, the second control valve, and the flow meter; and the cooling liquid-circulation system is connected to a liquid pump configured to make a cooling liquid circularly flow in the liquid cooling device. The heating control system can further include temperature-measuring thermocouples respectively arranged in the heating zone and the condensing zone, where the temperature-measuring thermocouples are configured to measure temperatures of the heating zone and the condensing zone, respectively, control the heating of the heating unit according to a set temperature range, and adjust actuations of the cooling liquid-circulation system and the gas control system according to measured temperatures.

The apparatus further includes top cover 5. Those skilled in the art can understand that the top cover 5 has a similar function to a furnace door, and the internal space of the furnace body can be opened or closed by opening or closing the top cover 5 to place or take out the raw material.

Example 2

A method for preparing high-purity spherical magnesium and/or a high-purity magnesium powder with the apparatus for preparing high-purity spherical magnesium and/or a high-purity magnesium powder in Example 1 was provided, including the following steps:

• • S10. Crude magnesium or a magnesium ingot was added to the crucible, the crucible was placed in the heating zone, the filtering device and the plurality of collection devices were arranged sequentially above the crucible, and the vertical furnace body was sealed.
  • S20. The vacuum pump and the first control valve were turned on to allow vacuuming. When a vacuum degree in the vertical furnace body reached a preset vacuum degree, heating of the heating zone was started, both the second control valve and the cooling liquid-circulation system were turned on, and an inert gas was introduced into the condensing zone.

A temperature of the heating zone was controlled at 650° C. to 1,500° C., a gas flow rate was adjusted by the second control valve to 1 LPM to 500 LPM, a cooling liquid flow rate was adjusted by the cooling liquid-circulation system to 1 LPM to 100 LPM, and a temperature of the condensing zone was controlled at 100° C. to 700° C. The temperature of the heating zone, the temperature of the condensing zone, the gas flow rate, and the cooling liquid flow rate were set according to a specific product to be prepared. For example, when the temperature of the heating zone was controlled at 650° C. to 900° C., the gas flow rate was adjusted by the second control valve to 200 LPM to 500 LPM, the cooling liquid flow rate was adjusted to 50 LPM to 100 LPM, and the temperature of the condensing zone was controlled at 100° C. to 400° C., the high-purity magnesium powder alone was obtained; when the temperature of the heating zone was controlled at 900° C. to 1,500° C., the gas flow rate was adjusted by the second control valve to 1 LPM to 200 LPM, the cooling liquid flow rate was adjusted to 1 LPM to 50 LPM, and the temperature of the condensing zone was controlled at 400° C. to 700° C., the high-purity spherical magnesium alone was obtained; and when the temperature of the heating zone was controlled at 800° C. to 1,300° C. and preferably 900° C. to 1,200° C., the gas flow rate was controlled at 100 LPM to 400 LPM and preferably 200 LPM and 300 LPM, the cooling liquid flow rate was controlled at 30 LPM to 70 LPM and preferably 40 LPM to 60 LPM, and a temperature of a condensate was controlled at 200° C. to 600° C., both the high-purity spherical magnesium and the high-purity magnesium powder were obtained.

• • S30. When the crude magnesium or the magnesium ingot evaporated completely, the heating was stopped; and when a temperature of a product dropped to room temperature, the gas circulation system and the cooling liquid-circulation system were turned off, and the plurality of collection devices were taken out to collect the high-purity spherical magnesium and/or the high-purity magnesium powder.

The apparatus and method of the present disclosure are implemented as follows: Based on principles such as different saturation vapor pressures of different elements, evaporation and condensation, molecular collision, and nucleation crystallization, crude magnesium or a magnesium ingot is taken as a raw material, the raw material is heated at an appropriate temperature to make magnesium evaporated and impurities with low saturation vapor pressures remain, then the evaporated magnesium vapor is further purified by the filtering device, and the purified magnesium vapor collides with introduced gas molecules to varying degrees to lose heat and carried by the gas flow to the condensing zone. Through dual cooling effects of water cooling outside the furnace body and gas cooling inside the furnace body, combined with the flexible arrangement of the thermal insulation devices in the condensing zone, and the adjustment of condensation water and gas flow rates, a nucleation crystallization process of the magnesium vapor is controlled such that the magnesium vapor is condensed to produce high-purity spherical magnesium or a high-purity magnesium powder.

Specifically, if a high-purity magnesium powder needs to be prepared, a heating temperature is controlled at a relatively-low level and is preferably controlled at 650° C. to 900° C. to prevent a large amount of magnesium from volatilizing simultaneously and growing in an agglomeration manner in the condensing zone; and a gas flow rate and a cooling water flow rate are controlled at relatively-high levels and are preferably controlled at 200 LPM to 500 LPM and 50 LPM to 100 LPM, respectively. During heating process, the raw material volatilizes slowly, and the magnesium vapor purified by the filtering device fully collides with introduced low-temperature gas molecules to lose a large amount of heat, and enters the condensing zone under a combined effect of the introduced gas flow and the pumping force of the vacuum pump. Due to there is no thermal insulation devices placed outside the condensing zone and a combined effect of introduced gas and liquid cooling, the temperature of the condensing zone can be controlled at 100° C. to 400° C., such that the magnesium vapor is cooled into solid particles after nucleation without growing up; and high-purity magnesium powders of different particle sizes collected on the collection devices can be sieved to obtain high-purity magnesium powder products of different specifications.

If high-purity spherical magnesium needs to be prepared, the heating temperature is controlled at a relatively-high level and is preferably controlled at 900° C. to 1,500° C. to ensure that an enough amount of magnesium vapor grows in an agglomeration manner in the condensing zone; and the gas flow rate and the cooling water flow rate are controlled at relatively-low levels and are preferably controlled at 1 LPM to 200 LPM and 1 LPM to 50 LPM, respectively. During heating process, the raw material volatilizes rapidly, and magnesium vapor purified by the filtering device collides with a low-temperature gas slowly introduced to lose a part of heat, and enters the condensing zone under a combined effect of the introduced gas flow and the pumping force of the vacuum pump. Due to the arrangement of the thermally-insulating materials and the control of the gas and cooling water flow rates at relatively-low levels, the temperature of the condensing zone can be controlled at 400° C. to 700° C., and a magnesium vapor is slowly cooled to produce spherical magnesium under an action of a surface tension. Spherical magnesium particles of different particle sizes collected by the collection devices at different locations can be sieved to obtain high-purity spherical magnesium products of different specifications.

If high-purity spherical magnesium and high-purity magnesium powder need to be prepared simultaneously, moderate production conditions are provided, that is, the temperature of the heating zone is controlled at 800° C. to 1,300° C., the gas flow rate is controlled at 100 LPM to 400 LPM, the cooling water flow rate is controlled at 30 LPM to 70 LPM, and the temperature of a condensate is controlled at 200° C. to 600° C. (preferably, the temperature of the heating zone is controlled at 900° C. to 1,200° C., the gas flow rate is controlled at 200 LPM to 300 LPM, and the cooling water flow rate is controlled at 40 LPM to 60 LPM). The magnesium vapor volatilized during heating collides with gas molecules and is carried by a gas flow to the condensing zone; in a lower condensing zone with a thermally-insulating layer arranged, due to a relatively-high temperature, the magnesium vapor is slowly cooled to produce the high-purity spherical magnesium; and in an upper condensing zone without a thermally-insulating layer arranged, the magnesium vapor is rapidly condensed into a solid state without growing up to produce the high-purity magnesium powder. That is, high-purity spherical magnesium and high-purity magnesium powder can be prepared simultaneously.

In the above processes, the introduced gas and cooling water can be collected and reused. According to test results, purities of the prepared high-purity spherical magnesium and high-purity magnesium powder products can reach 99.999%.

Example 3

(1) Material Loading

5 kg of crude magnesium was added to the crucible, the crucible was placed in the heating zone, the filtering device, the collection devices, and the top cover were arranged sequentially above the crucible; and the furnace cover was closed, and the apparatus was sealed.

(2) Vacuuming

When it was checked that the apparatus was normal and the arrangement was correct, the heating zone was heated to 700° C. and kept at this temperature for 120 min, and the vacuum pump was turned on and kept running.

(3) Preparation of a High-Purity Magnesium Powder

The heating program was started, the gas flow rate was controlled at 400 LPM, and the cooling water flow rate was controlled at 80 LPM. During the heating process, the raw material volatilized slowly; and the magnesium vapor purified by the filtering device collided with introduced low-temperature gas molecules to lose a large amount of heat, and entered the condensing zone under the combined effect of the introduced gas flow and the vacuum pump. Due to no arrangement of thermal insulation devices in the condensing zone and a combined effect of an introduced large gas flow and water cooling, the temperature of the condensing zone was controlled at 200° C., and the magnesium vapor was directly transformed from a gas phase into a solid phase on the collection devices after nucleation without growing up to produce the high-purity magnesium powder. High-purity magnesium powders collected on the collection devices were sieved to obtain products of different specifications. The cooling water and introduced gas could be collected and reused.

Example 4

(1) Material Loading

5 kg of a magnesium ingot was added to the crucible, the crucible was placed in the heating zone, the filtering device, the collection devices, and the top cover were arranged sequentially above the crucible, and the first and second thermal insulation devices were arranged at peripheries of the collection devices; and the furnace cover was closed, and the apparatus was sealed.

(2) Vacuuming

When it was checked that the apparatus was normal and the arrangement was correct, the heating zone was heated to 1,200° C. and kept at this temperature for 60 min, and the vacuum pump was turned on and kept running.

(3) Preparation of High-Purity Spherical Magnesium

The heating program was started, the gas flow rate was controlled at 100 LPM, and the cooling water flow rate was controlled at 30 LPM. During the heating process, the raw material volatilized rapidly; and the magnesium vapor purified by the filtering device collided with introduced low-temperature gas molecules to lose a part of heat, and entered the condensing zone under the combined effect of the introduced gas flow and the vacuum pump. Due to the arrangement of thermal insulation devices in the condensing zone and relatively-low gas and cooling water flow rates, a temperature of the condensing zone was controlled at 650° C., and the magnesium vapor was not cooled immediately after entering the condensing zone, but was transformed into liquid state and underwent nucleation and growth on the collection devices to produce the high-purity spherical magnesium. High-purity spherical magnesium collected on the collection devices was sieved to obtain products of different specifications. The cooling water and introduced gas could be collected and reused.

Example 5

(1) Material Loading

5 kg of a magnesium ingot was added to the crucible, the crucible was placed in the heating zone, the filtering device, the collection devices, and the top cover were arranged sequentially above the crucible, and the first thermal insulation device was arranged at a periphery of the condensing zone; and the furnace cover was closed, and the apparatus was sealed.

(2) Vacuuming

When it was checked that the apparatus was normal and the arrangement was correct, the heating zone was heated to 850° C. and kept at this temperature for 90 min, and the vacuum pump was turned on and kept running.

(3) Preparation of High-Purity Spherical Magnesium and High-Purity Magnesium Powder

The heating program was started, the gas flow rate was controlled at 200 LPM, and the cooling water flow rate was controlled at 50 LPM. When the raw material volatilized, the magnesium vapor passed through the filtering device and then entered the condensing zone, which had the same principle as in the above examples. Because a temperature gradient between the lower condensing zone and the heating zone was small, the magnesium vapor was slowly cooled and grew up to produce the spherical magnesium; and because a temperature gradient between the upper condensing zone and the heating zone was large, the magnesium vapor was condensed into the magnesium powder without growing up. Products collected on the collection devices were sieved to obtain products of different specifications. The cooling water and introduced gas could be collected and reused.

Impurity contents and purities of the high-purity spherical magnesium and high-purity magnesium powder prepared by the apparatus and method of the present disclosure were shown in Table 1, and SEM images of the high-purity spherical magnesium and high-purity magnesium powder were shown in FIGS. 2A-2D.

TABLE 1
Impurity contents and purity (ppm) of the high-purity spherical magnesium and
high-purity magnesium powder
	Al	Mn	Si	Fe	Cu	Ni	Pb	Sn	Ca	Ti	Zn	Na	K
Spherical	0.7	1.8	2	0.5	0	0.3	0.4	0.3	1	0.01	1	0.8	1
magnesium
Magnesium	0.5	1.2	4	0.1	0.1	0	0.5	0	2	0.01	0.2	0.3	0.5
powder

It can be seen that the impurity content in high-purity spherical magnesium and high-purity magnesium powder prepared in the present disclosure are both less than 5 ppm and the purity are greater than 5 N, where the purity can be calculated by a subtraction method. The high-purity spherical magnesium has excellent sphericity; and the high-purity magnesium powder has a smooth surface and distinct particles. The two products both have a high purity and a large SSA, and can be sieved to obtain spherical magnesium and magnesium powder products of different specifications, which can meet the use requirements in fields such as reducing agents, desulfurizing agents, chemical products, and 3D printing.

It should be noted that the apparatus and method for preparing high-purity spherical magnesium and/or high-purity magnesium powder involved in the embodiments of the present disclosure may be used in experimental research or normal production.

The above descriptions are merely preferred examples of the present disclosure, and not intended to limit the present disclosure. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present disclosure should fall within the protection scope of the present disclosure.

Claims

1. An apparatus for preparing high-purity spherical magnesium and/or a high-purity magnesium powder, comprising a vertical furnace body, a heating zone, and a condensing zone, wherein the heating zone and the condensing zone are arranged in the vertical furnace body, and the heating zone is located below the condensing zone;

a periphery of the heating zone is provided with a heating unit;

a periphery of the condensing zone is provided with a first thermal insulation device and a second thermal insulation device sequentially from bottom to top, and each of the first thermal insulation device and the second thermal insulation device is removably arranged;

the periphery of the condensing zone is further provided with a liquid cooling device;

a gas inlet and a gas outlet are arranged in the condensing zone;

an inner wall of the condensing zone is provided with an arrangement structure configured to arrange a collection device.

2. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 1, further comprising a filtering device removably arranged between the heating zone and the condensing zone.

3. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 2, further comprising a plurality of collection devices, wherein a width of each of the plurality of collection devices is greater than a half of a diameter of the vertical furnace body and smaller than the diameter of the vertical furnace body, and the plurality of collection devices are staggered on the inner wall of the condensing zone.

4. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 1, wherein the liquid cooling device comprises a cooling liquid inlet, a cooling liquid outlet, and a cooling pipeline; the cooling liquid outlet is formed at a top of a side wall surface of the vertical furnace body corresponding to the condensing zone; the cooling pipeline is coiled on an outer wall surface of the heating zone and/or the condensing zone; and the cooling liquid inlet is formed at a bottom of the side wall surface of the vertical furnace body corresponding to the heating zone or the condensing zone.

5. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 4, further comprising: a vacuum pump and a gas storage device, wherein the vacuum pump is connected to the gas outlet through a pipeline and a first control valve, and the gas storage device is connected to the gas inlet through a pipeline, a second control valve, and a flow meter.

6. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 5, further comprising a control system, wherein the control system comprises a heating control system, a gas control system, and a cooling liquid-circulation system;

the heating control system is connected to the heating unit and temperature sensors respectively arranged in the heating zone and the condensing zone;

the gas control system is connected to the vacuum pump, the first control valve, the second control valve, and the flow meter;

the cooling liquid-circulation system is connected to a liquid pump configured to make a cooling liquid circularly flow in the liquid cooling device.

7. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 6, further comprising a crucible arranged in the heating zone.

8. A method for preparing high-purity spherical magnesium and/or a high-purity magnesium powder with the apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 1, comprising the following steps:

S10, adding crude magnesium or a magnesium ingot to a crucible, placing the crucible in the heating zone, sequentially arranging a filtering device and a plurality of collection devices above the crucible, and sealing the vertical furnace body;

S20, turning on a vacuum pump and a first control valve to allow vacuuming; when a vacuum degree in the vertical furnace body reaches a preset vacuum degree, starting to heat the heating zone, and turning on both a second control valve and a cooling liquid-circulation system to make a gas and a cooling liquid flow, wherein the gas is a gas that does not react with a magnesium vapor, and the cooling liquid is a cooling medium of water or oil; and

controlling a temperature of the heating zone at 650° C. to 1,500° C., adjusting a gas flow rate by the second control valve to 1 LPM to 500 LPM, adjusting a cooling liquid flow rate to 1 LPM to 100 LPM, and controlling a temperature of the condensing zone at 100° C. to 700° C.; and

S30, when the crude magnesium or the magnesium ingot evaporates completely, stopping the heating; and when a temperature in a furnace drops to room temperature, turning off a gas control system and the cooling liquid-circulation system, and taking the plurality of collection devices out to obtain the high-purity spherical magnesium and/or the high-purity magnesium powder.

9. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 8, wherein when the temperature of the heating zone is controlled at 650° C. to 900° C., the gas flow rate is adjusted by the second control valve to 200 LPM to 500 LPM, the cooling liquid flow rate is adjusted to 50 LPM to 100 LPM, and the temperature of the condensing zone is controlled at 100° C. to 400° C., the high-purity magnesium powder alone is obtained; when the temperature of the heating zone is controlled at 900° C. to 1,500° C., the gas flow rate is adjusted by the second control valve to 1 LPM to 200 LPM, the cooling liquid flow rate is adjusted to 1 LPM to 50 LPM, and the temperature of the condensing zone is controlled at 400° C. to 700° C., the high-purity spherical magnesium alone is obtained; and when the temperature of the heating zone is controlled at 800° C. to 1,300° C. and preferably 900° C. to 1,200° C., the gas flow rate is controlled at 100 LPM to 400 LPM and preferably 200 LPM and 300 LPM, the cooling liquid flow rate is controlled at 30 LPM to 70 LPM and preferably 40 LPM to 60 LPM, and a temperature of a condensate is controlled at 200° C. to 600° C., both the high-purity spherical magnesium and the high-purity magnesium powder are obtained.

10. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 9, wherein when the high-purity magnesium powder alone is prepared, the first thermal insulation device and the second thermal insulation device are removed; when the high-purity spherical magnesium alone is prepared, the first thermal insulation device and the second thermal insulation device are arranged; and when both the high-purity spherical magnesium and the high-purity magnesium powder are prepared, the first thermal insulation device is arranged, and the second thermal insulation device is removed.

11. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 2, wherein the liquid cooling device comprises a cooling liquid inlet, a cooling liquid outlet, and a cooling pipeline; the cooling liquid outlet is formed at a top of a side wall surface of the vertical furnace body corresponding to the condensing zone; the cooling pipeline is coiled on an outer wall surface of the heating zone and/or the condensing zone; and the cooling liquid inlet is formed at a bottom of the side wall surface of the vertical furnace body corresponding to the heating zone or the condensing zone.

12. The apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 3, wherein the liquid cooling device comprises a cooling liquid inlet, a cooling liquid outlet, and a cooling pipeline; the cooling liquid outlet is formed at a top of a side wall surface of the vertical furnace body corresponding to the condensing zone; the cooling pipeline is coiled on an outer wall surface of the heating zone and/or the condensing zone; and the cooling liquid inlet is formed at a bottom of the side wall surface of the vertical furnace body corresponding to the heating zone or the condensing zone.

13. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 8, wherein the apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder further comprises the filtering device removably arranged between the heating zone and the condensing zone.

14. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 13, wherein the apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder further comprises the plurality of collection devices, a width of each of the plurality of collection devices is greater than a half of a diameter of the vertical furnace body and smaller than the diameter of the vertical furnace body, and the plurality of collection devices are staggered on the inner wall of the condensing zone.

15. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 8, wherein the liquid cooling device comprises a cooling liquid inlet, a cooling liquid outlet, and a cooling pipeline; the cooling liquid outlet is formed at a top of a side wall surface of the vertical furnace body corresponding to the condensing zone; the cooling pipeline is coiled on an outer wall surface of the heating zone and/or the condensing zone; and the cooling liquid inlet is formed at a bottom of the side wall surface of the vertical furnace body corresponding to the heating zone or the condensing zone.

16. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 15, wherein the apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder further comprises the vacuum pump and a gas storage device, wherein the vacuum pump is connected to the gas outlet through a pipeline and the first control valve, and the gas storage device is connected to the gas inlet through a pipeline, the second control valve, and a flow meter.

17. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 16, wherein the apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder further comprises a control system, wherein the control system comprises a heating control system, the gas control system, and the cooling liquid-circulation system;

the heating control system is connected to the heating unit and temperature sensors respectively arranged in the heating zone and the condensing zone;

the gas control system is connected to the vacuum pump, the first control valve, the second control valve, and the flow meter;

the cooling liquid-circulation system is connected to a liquid pump configured to make a cooling liquid circularly flow in the liquid cooling device.

18. The method for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder according to claim 17, wherein the apparatus for preparing the high-purity spherical magnesium and/or the high-purity magnesium powder further comprises the crucible arranged in the heating zone.