Production method of high-purity red phosphorus

Abstract

The invention relates to a production method of high-purity red phosphorus, which comprises the following steps: placing high-purity white phosphorus in an inner-layer high-purity quartz tube, inserting the inner-layer high-purity quartz tube into an outer-layer high-purity quartz tube after the high-purity white phosphorus is cooled and solidified, installing a stainless steel tube joint at an opening of the outer-layer high-purity quartz tube, inserting the closed outer-layer high-purity quartz tube into an infrared electric heater, and heating the outer-layer high-purity quartz tube to obtain the high-purity red phosphorus. After the infrared electric heater is plugged into the stainless steel sealed pressure container, a sealing head is mounted; the stainless steel sealed pressure container is sealed; preheating and liquefying the high-purity white phosphorus in a nitrogen protection normal pressure state until the moisture of the high-purity white phosphorus is completely evaporated; pressurizing the outer layer high-purity quartz tube, maintaining the balance of the internal pressure and the external pressure, and heating to 350-380 DEG C; and when the temperature is reduced to be within 250 DEG C, forced cooling and discharging are carried out on the stainless steel sealed pressure container. According to the invention, the nested inner-layer high-purity quartz tube and outer-layer high-purity quartz tube are adopted, discharging is carried out in the inner-layer high-purity quartz tube, red phosphorus is convenient to take out, nitrogen is filled inside and outside the outer-layer high-purity quartz tube, pressure balance inside and outside the outer-layer high-purity quartz tube is maintained, and safety is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of element phosphorus, and in particular to a method for producing high-purity red phosphorus. Background Art

[0002] High-purity red phosphorus can be used to synthesize semiconductor materials such as indium phosphide (InP), gallium phosphide (GaP), aluminum gallium arsenide phosphide (AlGaAsP), indium gallium arsenide phosphide (InGaAsP), and gallium arsenide phosphide (GaAsP). These materials have the advantages of high electron mobility, high frequency response, and low noise, and are key components of high-performance electronic and optoelectronic devices.

[0003] At present, the method of producing high-purity red phosphorus is basically to directly convert yellow phosphorus (white phosphorus) into red phosphorus. The conversion forms are roughly divided into two types: 1. High-pressure conversion: Patent CN101214935B discloses the "production process of electronic-grade red phosphorus". High-purity yellow phosphorus is transferred into a conversion pot, and 1-2 kg of inert gas is added at 20°C-80°C, 2-4 kg of inert gas is added at 80°C-200°C, no inert gas is added at 200°C-250°C, 1-2 kg of inert gas is added at 250°C-280°C, and 1-2 kg of inert gas is added at 280°C-300°C. The product is naturally cooled to room temperature to obtain a 99.9999% high-purity red phosphorus product. However, this method has relatively high requirements on equipment, and high-pressure conditions also pose safety risks.

[0004] 2. Normal pressure conversion: In the latest technology of converting yellow phosphorus into high-purity red phosphorus at normal pressure, patent number CN109081320A discloses "a device and method for converting electronic grade high-purity yellow phosphorus into red phosphorus". The device consists of a converter, a heater, a temperature controller, a condenser, and an exhaust water seal. The method is as follows: (1) placing high-purity yellow phosphorus in a converter, covering it with ultra-high purity water, and heating the converter until the water is completely evaporated; (2) continuously passing warm water into the condenser to condense the yellow phosphorus vapor, and at the same time controlling the heater to slowly heat the converter to 350°C, and then controlling the temperature within the range of 350°C to 370°C for 24 hours; (3) after the yellow phosphorus is completely converted into red phosphorus, stop heating, cool it naturally, and at the same time pass an inert gas into the converter. After it cools to room temperature, place the converter in pure water and smash the converter to obtain red phosphorus. This method has losses during the reaction process, and the yield of high-purity red phosphorus is not high, at about 92%. Under the same conversion efficiency, the time is long or the conversion cannot be complete, and post-processing such as alkaline solution purification and washing is required to ensure quality. Summary of the invention

[0005] The object of the present invention is to overcome the above-mentioned shortcomings and provide a production method of high-purity red phosphorus, which can realize batch production of high-purity red phosphorus of 6N (99.9999%) to 9N (99.999999%) grades, can effectively stabilize the quality of red phosphorus products, maintain high yield requirements, reduce safety risks, have strong operability, reliable system and relatively low cost.

[0006] The object of the present invention is achieved in that: A method for producing high-purity red phosphorus comprises the following steps: Step 1, placing high-purity white phosphorus in an inner high-purity quartz tube, covering the high-purity white phosphorus with high-purity water, inserting the inner high-purity quartz tube into the outer high-purity quartz tube after the high-purity white phosphorus is cooled and solidified, installing a stainless steel pipe joint at the opening of the outer high-purity quartz tube, inserting the sealed outer high-purity quartz tube into the infrared electric heater, inserting the infrared electric heater into a stainless steel sealed pressure vessel, installing a head, and sealing the stainless steel sealed pressure vessel; Step 2: Use a vacuum system and a nitrogen system to evacuate and inject nitrogen into the outer high-purity quartz tube, and after the air in the outer high-purity quartz tube is completely replaced, turn on the infrared electric heater to preheat the high-purity white phosphorus in the inner high-purity quartz tube to liquefy the high-purity white phosphorus, and supplement nitrogen during this period to make the pressure in the inner quartz tube at normal pressure; Step 3: Continue to slowly raise the temperature to 120°C-150°C, and perform vacuum treatment again until the water content of the high-purity white phosphorus is completely evaporated; The outer high-purity quartz tube is filled with nitrogen and the pressure is slowly increased to 0.2MPa-0.5MPa, then the nitrogen valve is closed, and while the pressure in the outer high-purity quartz tube is increased, nitrogen is introduced synchronously through the nitrogen filling and discharging port of the stainless steel sealed pressure vessel, and the positive pressure difference between the inner and outer layers of the outer high-purity quartz tube is maintained at 0.05MPa-0.10MPa, and then the temperature is slowly increased in stages until the temperature reaches 350℃-380℃; Step 4: After the heating is completed, cool naturally for a period of time, and when the temperature drops to below 250°C, start forced cooling and discharging of the stainless steel sealed pressure container.

[0007] Preferably, in the step 1, some high-purity hot water is first added to the inner high-purity quartz tube through a feeding system to a position of one-third of the volume, and the temperature of the high-purity hot water is controlled at 60°C-80°C. Then, the feeding tube is inserted into the through hole of the inner high-purity quartz tube to below the liquid level of the high-purity hot water, and a measured amount of liquid high-purity white phosphorus is injected. Then, the inner high-purity quartz tube with white phosphorus is placed in water at a temperature of 20°C to cool and solidify the white phosphorus.

[0008] Preferably, in the step 2, the temperature is stopped after preheating to 80°C-90°C, and then a vacuum pump is started to perform a vacuum operation, and the vacuum degree can be controlled at 200 mmHg-400 mmHg to gradually and completely volatilize the moisture on the surface of the white phosphorus.

[0009] Preferably, in step three, the temperature is continued to rise to a range of 350° C.-380° C. from the time when the water in the white phosphorus is completely evaporated, and the time lasts for 40 hours, during which the heating is suspended twice.

[0010] Preferably, in step 4, the circulating water pump is started, and the circulating water enters and exits the jacket of the stainless steel sealed pressure vessel for cooling. As the temperature drops, the pressure difference between the inside and outside of the outer high-purity quartz tube changes. At this time, the nitrogen is automatically released or supplemented by coordinating two automatic control regulating valves, so that the pressure difference between the inside and outside of the quartz tube can always be controlled within a pressure difference of 0.1 MPa.

[0011] Preferably, in step one, the stainless steel pipe joint extends out of the sealing head of the stainless steel sealed pressure vessel and is respectively connected to a nitrogen system and a vacuum system. The stainless steel sealed pressure vessel is also provided with a nitrogen charging and discharging port, and the nitrogen charging and discharging port is connected to the nitrogen system.

[0012] Preferably, the nitrogen system includes a nitrogen buffer tank and a nitrogen bottle, the vacuum system includes a vacuum buffer tank and a vacuum pump, the nitrogen bottle is connected to the nitrogen buffer tank, the nitrogen buffer tank is respectively connected to the nitrogen charging and discharging ports and the stainless steel pipe joint through pipelines, the stainless steel pipe joint is also connected to the vacuum buffer tank in parallel, the vacuum buffer tank is connected to the exhaust buffer tank through the vacuum pump, the exhaust vacuum tank is provided with an exhaust port and a nitrogen replenishing port, and the nitrogen replenishing port is connected to the nitrogen buffer tank.

[0013] Preferably, the wires of the infrared electric heater extend out of the stainless steel sealed pressure container and are sealed and insulated by a wire sealing and heat-insulating assembly.

[0014] The beneficial effects of the present invention are: 1. It can realize the conversion of white phosphorus under relatively high pressure. At the same time, it can balance and control the heated quartz tube and its connection seal at a high temperature of 350℃ by adjusting the filling and releasing of nitrogen through the internal and external pressure difference control, thereby reducing the risk of seal failure and leakage due to high internal pressure; 2. By adding sufficient nitrogen pressure into the outer high-purity quartz tube, the boiling point of white phosphorus can be increased so that it does not volatilize at the boiling point of 280°C to produce white phosphorus vapor, which causes the gaseous white phosphorus to overflow from the inner high-purity quartz tube during conversion and enter the outer high-purity quartz tube for conversion, thereby reducing the need to clean the red phosphorus in the outer high-purity quartz tube and increasing the total yield of the finished red phosphorus; 3. Installing a stainless steel sealed pressure vessel outside the infrared electric heater can prevent the safety risk of white phosphorus liquid or gas leakage caused by quartz tube aging and cracking due to thermal expansion and contraction; 4. Infrared heating is adopted, with precise temperature control. At the same time, it can heat without conventional conduction method of material contact. The characteristic of infrared heating is that radiation heat transfer is the main method, accounting for about 90%. Radiation heat transfer is mainly used to transfer heat to the inner layer of high-purity quartz tube, making the design of inner and outer layer high-purity quartz tube possible; when discharging, only the low-cost inner layer high-purity quartz tube needs to be broken, and the high-cost outer layer high-purity quartz tube can be reused, which greatly reduces the equipment cost; 5. The wires of the infrared electric heater extend out of the stainless steel sealed pressure vessel and are sealed and insulated through the wire sealing and insulation components to ensure the sealing and safety of the container. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a schematic structural diagram of a high-purity red phosphorus production device.

[0016] Figure 2 It is a schematic diagram of the assembly structure of the stainless steel sealed pressure vessel of the present invention.

[0017] Figure 3 This is a schematic diagram of the assembly structure of the wire sealing and insulation component.

[0018] Figure 4 It is a production process flow chart of the present invention.

[0019] Wherein: stainless steel sealed pressure vessel 1; nitrogen filling and discharging port 1.1; end cap 1.2; infrared electric heater 2; outer high-purity quartz tube 3; inner high-purity quartz tube 4; through hole 4.1; stainless steel pipe joint 5; nitrogen buffer tank 6; nitrogen bottle 7; vacuum buffer tank 8; vacuum pump 9; exhaust buffer tank 10; wire sealing and insulation assembly 11; air-cooling connector 11.1; stainless steel sheath 11.2; stainless steel capillary tube 11.3; porcelain tube 11.4; high-temperature resin 11.5; cable external interface plug 11.6; cooling water tank 12; circulating water pump 13; fixed base 14. DETAILED DESCRIPTION

[0020] See also Figure 1-4The present invention relates to a production device of high-purity red phosphorus, comprising a stainless steel sealed pressure vessel 1, an infrared electric heater 2, an outer high-purity quartz tube 3, an inner high-purity quartz tube 4, a nitrogen system, a vacuum system and a circulating water system. The stainless steel sealed pressure vessel 1 is equipped with an infrared electric heater 2, an outer high-purity quartz tube 3 is arranged inside the infrared electric heater 2, an inner high-purity quartz tube 4 is arranged inside the outer high-purity quartz tube 3, the infrared electric heater 2, the outer high-purity quartz tube 3 and the inner high-purity quartz tube 4 are all concentrically arranged, the inner high-purity quartz tube 4 is cylindrical, the two ends of the inner high-purity quartz tube 4 are closed, and two through holes 4.1 are arranged on the circumferential surface, the through holes have two functions, one is ventilation to balance the pressure; the other is used for high-purity white phosphorus and high-purity water to enter the inner high-purity quartz tube 4, the wall thickness of the inner high-purity quartz tube 4 is 2-6mm, and it does not bear pressure.

[0021] The outer high-purity quartz tube 3 is also cylindrical, and the wall thickness of the outer high-purity quartz tube 3 is 6 mm to 20 mm. It needs to withstand pressure, has high cost, and can be reused many times. One end of the outer high-purity quartz tube 3 is closed, and the other end is provided with an opening for the inner high-purity quartz tube 4 to enter. The opening is sealed and connected to a stainless steel pipe joint 5. The stainless steel pipe joint 5 extends out of the head 1.2 of the stainless steel sealed pressure vessel 1 and is respectively connected to a nitrogen system and a vacuum system. The gap between the stainless steel pipe joint 5 and the stainless steel sealed pressure vessel 1 is sealed.

[0022] The stainless steel sealed pressure container 1 is also provided with a nitrogen charging and discharging port 1.1, and the nitrogen charging and discharging port 1.1 is connected to a nitrogen system.

[0023] The nitrogen system includes a nitrogen buffer tank 6 and a nitrogen bottle 7, and the vacuum system includes a vacuum buffer tank 8, a vacuum pump 9 and an exhaust buffer tank 10. The nitrogen bottle 7 is connected to the nitrogen buffer tank 6. The nitrogen buffer tank 6 is respectively connected to the nitrogen charging and discharging port 1.1 and the stainless steel pipe joint 5 through pipelines. The stainless steel pipe joint 5 is also connected to the vacuum buffer tank 8 in parallel. The vacuum buffer tank 8 is used to collect condensed water vapor. The vacuum buffer tank 8 is connected to the exhaust buffer tank 10 through the vacuum pump 9. The exhaust vacuum tank 10 is provided with an exhaust port and a nitrogen replenishing port. The nitrogen replenishing port is connected to the nitrogen buffer tank 6. The nitrogen buffer tank 6 continuously releases nitrogen to the exhaust vacuum tank 10 to ensure that there is sufficient nitrogen in the exhaust buffer tank to prevent the danger of air backflow caused by the return gas backflow caused by abnormal stop or operation of the vacuum pump.

[0024] The wire of the infrared electric heater 2 extends out of the stainless steel sealed pressure vessel 1 and is sealed and insulated by a wire sealing and heat-insulating assembly 11. The wire sealing and heat-insulating assembly 11 includes an air-cooling connector 11.1, a stainless steel sheath 11.2 and a stainless steel capillary 11.3. The stainless steel sealed pressure vessel 1 is provided with a flange corresponding to the wire of the infrared electric heater 2. The air-cooling connector 11.1 is sealedly connected to the flange of the stainless steel sealed pressure vessel 1. The air-cooling connector 11.1 is connected to the stainless steel sheath 11.2. Three stainless steel capillary 11.3 are provided in the stainless steel sheath 11.2. One end of the stainless steel capillary 11.3 is welded to the air-cooling connector 11.1, and the other end is cast and fixed by a high-temperature resin 11.5. A porcelain tube 11.4 is arranged inside the steel capillary tube 11.3, and a conducting wire is arranged inside the porcelain tube 11.4. The porcelain tube 11.4 through which the conducting wire is passed isolates the conducting wire from the stainless steel sheath and the stainless steel capillary tube, thereby avoiding the danger of a short circuit caused by the conducting wire contacting the stainless steel. The conducting wire is connected to the cable external interface plug 11.6 through the porcelain tube 11.4. The three conducting wires in the cable external interface plug 11.6 are combined into one and then connected to an external power supply. A water cooling cavity is formed between the high temperature resin 11.5 in the stainless steel sheath 11.2 and the air cooling connector 11.1. Circulating cooling water is arranged in the water cooling cavity. The high temperature gas and heat generated by the internal heating of the stainless steel sealed pressure vessel are prevented from being conducted to one end of the high temperature resin through water cooling, thereby effectively preventing thermal damage and sealing failure of the high temperature resin.

[0025] The stainless steel sealed pressure vessel 1 is provided with a cooling jacket, and circulating water is arranged in the jacket to facilitate cooling after the conversion of high-purity white phosphorus is completed.

[0026] The circulating water system cools the conductor sealing and heat-insulating assembly 11 and the stainless steel sealed pressure vessel at the same time. The circulating water system comprises a cooling water tank 12 and a circulating water pump 13. The circulating water in the cooling water tank 12 is pumped to the jacket of the stainless steel sealed pressure vessel 1 and the water cooling cavity of the conductor sealing and heat-insulating assembly 11 respectively by the circulating water pump 13, and then flows into the cooling water tank 12 after heat exchange.

[0027] The stainless steel sealed pressure container 1 is cylindrical and placed horizontally, and a fixed base 14 is provided at the bottom of the stainless steel sealed pressure container 1 .

[0028] The infrared electric heater 2 mainly utilizes radiation heat transfer to conduct heat to the inner layer of high-purity quartz tube, making it possible to design inner and outer layer high-layer quartz tubes. The infrared electric heater is equipped with a temperature controller, which can accurately control the temperature rise and the white phosphorus conversion temperature. The temperature rise range and temperature rise speed or staged temperature rise can be freely adjusted.

[0029] A method for producing high-purity red phosphorus comprises the following steps: Step 1: Place the measured high-purity white phosphorus with a purity of 6N-9N in the inner high-purity quartz tube 4. For safe operation, the high-purity white phosphorus is covered with high-purity water. The high-purity water and high-purity white phosphorus enter through the through hole 4.1, and the through hole is arranged upward; First, some high-purity hot water is added to the inner high-purity quartz tube through the feeding system to one-third of the volume, and the temperature of the high-purity hot water is controlled at 60°C-80°C. Then, the feeding tube is inserted into the through hole of the inner high-purity quartz tube to below the liquid level of the high-purity hot water, and a measured amount of liquid high-purity white phosphorus is injected. Then, the inner high-purity quartz tube with white phosphorus is placed in water at a temperature of 20°C to cool to solidify the white phosphorus. After the liquid white phosphorus is solidified, the inner high-purity quartz tube is inserted into the outer high-purity quartz tube, and a stainless steel pipe joint is installed in the outer high-purity quartz tube. At the same time, the outer high-purity quartz tube is inserted into the infrared electric heater. The infrared electric heater is inserted into a stainless steel sealed pressure vessel and a head is installed.

[0030] Step 2: vacuuming and injecting nitrogen into the outer high-purity quartz tube using a vacuum system and a nitrogen system, replacing the air in the outer high-purity quartz tube with nitrogen for 3-4 times, reducing the oxygen content in the outer high-purity quartz tube to less than 100 ppm, starting the infrared electric heater to preheat the high-purity white phosphorus in the inner high-purity quartz tube, slowly heating (20°C / hour) to 80°C-90°C and then stopping the heating to liquefy the high-purity white phosphorus, and then starting the vacuum pump to perform vacuuming operation, the vacuum degree can be controlled at 200 mmHg-400 mmHg, gradually volatilizing the moisture on the surface of the white phosphorus until the vacuum degree is increased to more than 730 mmHg, and then replenishing nitrogen to make the pressure in the inner quartz tube normal pressure state; Step 3, continue to slowly increase the temperature (30℃ / hour) to 120℃-150℃, and evacuate again until the vacuum degree reaches more than 730 mmHg, maintain for about 15 minutes, then add nitrogen, evacuate again and replace with nitrogen two to three times. After replacement, fill the outer high-purity quartz tube with nitrogen and slowly increase the pressure to 0.2MPa-0.5MPa, then close the nitrogen valve, while increasing the pressure in the outer high-purity quartz tube, simultaneously introduce nitrogen through the nitrogen filling and discharging port 1.1 of the stainless steel sealed pressure vessel 1, maintain the positive pressure difference between the inside and outside of the outer high-purity quartz tube at 0.05MPa-0.10MPa, and then continue to slowly increase the temperature in stages, and end when the temperature reaches 350℃-380℃; By adjusting the internal and external pressures, an operating pressure of at least 0.2MPa-0.5MPa is maintained in the inner high-purity quartz tube to increase the boiling point of white phosphorus, reduce the white phosphorus volatilizing out of the inner high-purity quartz tube 4 and accumulating on the inner wall surface of the outer high-purity quartz tube 3, and reduce the cleaning of broken red phosphorus formed on the inner wall surface of the outer high-purity quartz tube in the later stage and the reduction of the amount of finished red phosphorus.

[0031] The temperature starts at about 150℃ and rises to the range of 350℃-380℃ for about 40 hours, during which the heating is suspended twice. Specifically, the heating rate is controlled at 2℃ to 3℃ per hour. When the temperature rises to 265℃, the heating is suspended. At this time, the white phosphorus in the inner quartz tube will automatically start to heat up for a period of time due to the conversion to red phosphorus. After the automatic temperature rise ends, wait for the temperature to stabilize for 20 minutes, then continue to slowly heat up to 285℃, and then pause the heating for the second time. Maintain it for 20 minutes to observe whether the temperature continues to rise. After the temperature is constant, continue to turn on the infrared heating and control the heating rate to 2℃ per hour until the temperature reaches 330℃ and maintain it for 2 hours, and then heat it to 350℃ and maintain it for 3 hours.

[0032] Step 4: After the heating is completed, the material is naturally cooled for about 5 hours. When the temperature drops to below 250°C, the stainless steel sealed pressure vessel is forced to cool and discharge the material; Start the circulating water pump, and the circulating water enters and exits the jacket of the stainless steel sealed pressure vessel to cool down. As the temperature drops, the pressure difference between the inner and outer layers of the outer high-purity quartz tube will change. At this time, the nitrogen is automatically released or supplemented by the coordinated cooperation of two automatic control regulating valves, so that the pressure difference between the inner and outer layers of the quartz tube can always be controlled within the pressure difference of 0.1MPa. After the system temperature drops to room temperature, open the stainless steel sealed pressure vessel, take out the outer high-purity quartz tube and the inner high-purity quartz tube synchronously and place them in a high-purity water container under the water surface to isolate the air, and break the inner high-purity quartz tube 4 underwater to obtain block high-purity red phosphorus. After the block high-purity red phosphorus is cut into small particles with a special tool, take it out and place it in a vacuum drying oven with nitrogen protection at above 80°C for drying. After drying, the high-purity red phosphorus is weighed and packaged, and packaged in a brown clean glass container or a special bottle filled with nitrogen protection for storage. After passing the test, it can be sold. Example 1

[0033] A method for producing high-purity red phosphorus comprises the following steps: (1) 6 kg of high-purity yellow phosphorus with a purity of 6N-9N is placed in an inner high-purity quartz tube, covered with ultra-high-purity water, and the inner high-purity quartz tube containing solid white phosphorus is installed and placed in the outer high-purity quartz tube after cooling and solidification, and all pipelines are sealed and connected. After the system pressure test and leak test are normal, the vacuum pump is turned on, and the outer high-purity quartz tube is connected to evacuate four times, and at the same time, it is replaced with high-purity nitrogen four times to reduce the air in the outer high-purity quartz tube to less than 100PPm, and then nitrogen is added to normal pressure, and the infrared heater is turned on to heat the temperature in the outer high-purity quartz tube to 85°C, and then the heating is stopped, and the vacuum pump is turned on to evacuate until the water on the upper part of the white phosphorus in the outer high-purity quartz tube is completely evaporated and the vacuum degree rises to a level that no longer rises; (2) Add nitrogen to the quartz tube to maintain normal pressure, continue to turn on the infrared heater to slowly raise the temperature of the white phosphorus in the quartz tube to 130°C, and start the vacuum pump again to completely evaporate the bound water that may exist in the system and the water vapor that may exist in the bottom area of ​​the white phosphorus; (3) High-purity nitrogen is introduced again, and the pressure of high-purity nitrogen is inflated to 0.3MPa. At the same time, the pressure of the nitrogen outside the outer quartz tube is supplemented to offset the internal pressure, so as to balance and control the pressure difference between the inner and outer layers of the outer quartz tube to operate at a relatively low pressure difference. The pressure difference control method can be controlled by automatic control; (4) After the nitrogen filling is completed, the temperature control system is turned on to increase the temperature. The temperature rise rate is controlled at 8°C per hour. When the temperature rises to 265°C, the temperature rise is stopped. At this time, the white phosphorus in the inner quartz tube will automatically rise in temperature for a period of time due to the conversion to red phosphorus. After the automatic temperature rise ends, the temperature is slowly raised to 290°C. The temperature rise rate is controlled at 8°C per hour. The heating is stopped and maintained for 30 minutes to observe whether the temperature continues to rise. After the temperature is constant, the infrared heating gas is turned on to increase the temperature. The heating rate is controlled at 5°C per hour until the temperature rises to 330°C and maintained for 2 hours, and then the temperature rises to 350°C and maintained for 2 hours. Then stop heating, let the temperature drop naturally for about 3 hours, and start cooling and discharging.

[0034] (5) During the cooling operation, when the temperature in the jacket is lower than 250°C, start the water pump and control the slow water intake of the jacket to prevent the jacket from cooling sharply and causing uneven stress on the shell. The cooling water tank should be properly replenished with fresh cooling water. After cooling to room temperature, the container can be opened, the quartz tube can be disassembled, and the inner high-purity quartz tube containing red phosphorus can be taken out and placed in high-purity water for further cooling. Then the quartz tube can be broken, the red phosphorus can be taken out, and the red phosphorus can be cut into small particles underwater with a special tool and taken out. The particles are placed in a vacuum drying system for drying, and then weighed and packaged in brown clean glass containers protected by nitrogen to obtain 5.95 kg of high-purity red phosphorus.

[0035] After product sampling and processing, it was tested by a professional testing agency, and the test and analysis results of the impurity content are shown in Table 1.

[0036] Table 1 Impurity content detection and analysis results of Example 1 (unit: ppb, ND means not detected)

[0037] It can be seen that the quality of the product obtained by the method of the present invention fully meets the quality requirements of red phosphorus required for compound semiconductors such as indium phosphide (InP) and gallium phosphide (GaP). Example 2

[0038] A method for producing high-purity red phosphorus comprises the following steps: (1) 8 kg of high-purity yellow phosphorus with a purity of 6N-9N is placed in an inner high-purity quartz tube, covered with ultra-high-purity water, and the inner high-purity quartz tube containing solid white phosphorus is installed and placed in the outer high-purity quartz tube after cooling and solidification, and all pipelines are connected in a sealed manner. After the system pressure test and leak test are normal, the vacuum pump is turned on, and the outer high-purity quartz tube is connected to evacuate four times, and at the same time, it is replaced with high-purity nitrogen four times to reduce the air in the outer high-purity quartz tube to less than 100PPm, and then nitrogen is added to normal pressure, and the infrared heater is turned on to heat the temperature in the outer high-purity quartz tube to 90°C, and then the heating is stopped, and the vacuum pump is turned on to evacuate until the water on the upper part of the white phosphorus in the outer high-purity quartz tube is completely evaporated and the vacuum degree rises to a level that no longer rises; (2) Add nitrogen to the quartz tube to maintain normal pressure, continue to turn on the infrared heater to slowly raise the temperature of the white phosphorus in the quartz tube to 150°C, and start the vacuum pump again to completely evaporate the bound water that may exist in the system and the water vapor that may exist in the bottom area of ​​the white phosphorus; (3) High-purity nitrogen is introduced again, and the pressure of high-purity nitrogen is inflated to 0.3MPa. At the same time, the pressure of the nitrogen outside the outer quartz tube is supplemented to offset the internal pressure, so as to balance and control the pressure difference between the inner and outer layers of the outer quartz tube to operate at a relatively low pressure difference. The pressure difference control method can be controlled by automatic control; (4) After the nitrogen filling is completed, the temperature control system is turned on to increase the temperature. The temperature rise rate is controlled at 9°C per hour. When the temperature rises to 265°C, the temperature rise is stopped. At this time, the white phosphorus in the inner quartz tube will automatically rise in temperature for a period of time due to the conversion to red phosphorus. After the automatic temperature rise ends, the temperature is slowly raised to 290°C. The temperature rise rate is controlled at 9°C per hour. The heating is stopped and maintained for 30 minutes to observe whether the temperature continues to rise. After the temperature is constant, the infrared heating gas is turned on to increase the temperature. The heating rate is controlled at 6°C per hour until the temperature rises to 330°C and maintained for 2 hours, and then the temperature rises to 350°C and maintained for 1 hour. Then stop heating, let the temperature drop naturally for about 3 hours, and start cooling and discharging.

[0039] (5) During the cooling operation, when the temperature in the jacket is lower than 250°C, start the water pump and control the slow water intake of the jacket to prevent the jacket from cooling rapidly and causing uneven stress on the shell. The cooling water tank should be properly replenished with fresh cooling water. After cooling to room temperature, the container can be opened, the quartz tube can be disassembled, and the inner high-purity quartz tube containing red phosphorus can be taken out and placed in high-purity water for further cooling. Then the quartz tube can be broken, the red phosphorus can be taken out, and the red phosphorus can be cut into small particles underwater with a special tool and taken out. The particles are placed in a vacuum drying system for drying, and then weighed and packaged in brown clean glass containers protected by nitrogen to obtain 7.9 kg of high-purity red phosphorus.

[0040] After product sampling and processing, it was tested by a professional testing agency, and the test and analysis results of the impurity content are shown in Table 2.

[0041] Table 2 Impurity content detection and analysis results of Example 2 (unit: ppb, ND means not detected)

[0042] It can be seen that the quality of the product obtained by the method of the present invention fully meets the quality requirements of red phosphorus required for compound semiconductors such as indium phosphide (InP) and gallium phosphide (GaP). Example 3

[0043] A method for producing high-purity red phosphorus comprises the following steps: (1) 10 kg of high-purity yellow phosphorus with a purity of 6N-9N is placed in an inner high-purity quartz tube, covered with ultra-high-purity water, and the inner high-purity quartz tube containing solid white phosphorus is installed and placed in the outer high-purity quartz tube after cooling and solidification, and all pipelines are sealed and connected. After the system pressure test and leak test are normal, the vacuum pump is turned on, and the outer high-purity quartz tube is connected to evacuate four times, and at the same time, it is replaced with high-purity nitrogen four times to reduce the air in the outer high-purity quartz tube to less than 100PPm, and then nitrogen is added to normal pressure, and the infrared heater is turned on to heat the temperature in the outer high-purity quartz tube to 86°C, and then the heating is stopped, and the vacuum pump is turned on to evacuate until the water on the upper part of the white phosphorus in the outer high-purity quartz tube is completely evaporated and the vacuum degree rises to a level that no longer rises; (2) Add nitrogen to the quartz tube to maintain normal pressure, continue to turn on the infrared heater to slowly raise the temperature of the white phosphorus in the quartz tube to 145°C, and start the vacuum pump again to completely evaporate the bound water that may exist in the system and the water vapor that may exist in the bottom area of ​​the white phosphorus; (3) High-purity nitrogen is introduced again, and the pressure of high-purity nitrogen is inflated to 0.3MPa. At the same time, the pressure of the nitrogen outside the outer quartz tube is supplemented to offset the internal pressure, so as to balance and control the pressure difference between the inner and outer layers of the outer quartz tube to operate at a relatively low pressure difference. The pressure difference control method can be controlled by automatic control; (4) After the nitrogen filling is completed, the temperature control system is turned on to increase the temperature. The temperature rise rate is controlled at 10°C per hour. When the temperature rises to 270°C, the temperature rise is stopped. At this time, the white phosphorus in the inner quartz tube will automatically rise in temperature for a period of time due to the conversion to red phosphorus. After the automatic temperature rise ends, the temperature is slowly raised to 295°C. The temperature rise rate is controlled at 10°C per hour. The heating is stopped and maintained for 30 minutes to observe whether the temperature continues to rise. After the temperature is constant, the infrared heating gas is turned on to increase the temperature. The heating rate is controlled at 8°C per hour until the temperature rises to 330 degrees and maintained for 3 hours, and then the temperature rises to 350°C and maintained for 1 hour. Then stop heating, let the temperature drop naturally for about 2.5 hours, and start cooling and discharging.

[0044] (5) During the cooling operation, when the temperature in the jacket is lower than 250°C, start the water pump and control the slow water intake of the jacket to prevent the jacket from cooling sharply and causing uneven stress on the shell. The cooling water tank should be properly replenished with fresh cooling water. After cooling to room temperature, the container can be opened, the quartz tube can be disassembled, and the inner high-purity quartz tube containing red phosphorus can be taken out and placed in high-purity water for further cooling. Then the quartz tube can be broken, the red phosphorus can be taken out, and the red phosphorus can be cut into small particles underwater with a special tool and taken out. The particles are placed in a vacuum drying system for drying, and then weighed and packaged in brown clean glass containers protected by nitrogen to obtain 9.85 kg of high-purity red phosphorus.

[0045] After product sampling and processing, it was tested by a professional testing agency, and the test and analysis results of the impurity content are shown in Table 3.

[0046] Table 3 Impurity content detection and analysis results of Example 3 (unit: ppb, ND means not detected)

[0047] It can be seen that the quality of the product obtained by the method of the present invention fully meets the quality requirements of red phosphorus required for compound semiconductors such as indium phosphide (InP) and gallium phosphide (GaP).

[0048] In addition to the above embodiments, the present invention also includes other implementation modes. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the protection scope of the claims of the present invention.

Claims

1. A method for producing high-purity red phosphorus, characterized in that: The following steps are involved: Step 1, placing high-purity white phosphorus in an inner high-purity quartz tube, covering the high-purity white phosphorus with high-purity water, inserting the inner high-purity quartz tube into the outer high-purity quartz tube after the high-purity white phosphorus is cooled and solidified, installing a stainless steel pipe joint at the opening of the outer high-purity quartz tube, inserting the sealed outer high-purity quartz tube into the infrared electric heater, inserting the infrared electric heater into a stainless steel sealed pressure vessel, installing a head, and sealing the stainless steel sealed pressure vessel; Step 2: Use a vacuum system and a nitrogen system to evacuate and inject nitrogen into the outer high-purity quartz tube, and after the air in the outer high-purity quartz tube is completely replaced, turn on the infrared electric heater to preheat the high-purity white phosphorus in the inner high-purity quartz tube to liquefy the high-purity white phosphorus, and supplement nitrogen during this period to make the pressure in the inner quartz tube at normal pressure; Step 3: Continue to slowly raise the temperature to 120°C-150°C, and perform vacuum treatment again until the water content of the high-purity white phosphorus is completely evaporated; The outer high-purity quartz tube is filled with nitrogen and the pressure is slowly increased to 0.2MPa-0.5MPa, then the nitrogen valve is closed, and while the pressure in the outer high-purity quartz tube is increased, nitrogen is introduced synchronously through the nitrogen filling and discharging port of the stainless steel sealed pressure vessel, and the positive pressure difference between the inner and outer layers of the outer high-purity quartz tube is maintained at 0.05MPa-0.10MPa, and then the temperature is slowly increased in stages until the temperature reaches 350℃-380℃; Step 4: After the heating is completed, cool naturally for a period of time, and when the temperature drops to below 250°C, start forced cooling and discharging of the stainless steel sealed pressure container.

2. A method for producing high-purity red phosphorus according to claim 1, characterized in that: In the step 1, some high-purity hot water is first added to the inner high-purity quartz tube through the feeding system to a position of one-third of the volume, and the temperature of the high-purity hot water is controlled at 60° C.-80° C., and then the feeding tube is inserted into the through hole of the inner high-purity quartz tube to below the liquid level of the high-purity hot water, and a measured amount of liquid high-purity white phosphorus is injected, and then the inner high-purity quartz tube added with white phosphorus is placed in water at a temperature of 20° C. to cool and solidify the white phosphorus.

3. A method for producing high-purity red phosphorus according to claim 1, characterized in that: In the step 2, the temperature is stopped after preheating to 80° C.-90° C., and then the vacuum pump is started to perform a vacuum operation. The vacuum degree can be controlled at 200 mmHg-400 mmHg to gradually and completely volatilize the moisture on the surface of the white phosphorus.

4. The method for producing high-purity red phosphorus according to claim 1, characterized in that: In the step 3, the temperature is continuously raised to a range of 350° C. to 380° C. after the white phosphorus water is completely evaporated, and the time lasts for 40 hours, during which the heating is suspended twice.

5. The method for producing high-purity red phosphorus according to claim 1, characterized in that: In step 4, the circulating water pump is started, and the circulating water enters and exits the jacket of the stainless steel sealed pressure vessel for cooling. As the temperature drops, the pressure difference between the inside and outside of the outer high-purity quartz tube changes. At this time, the nitrogen is automatically released or supplemented by the coordinated cooperation of the two automatic control regulating valves, so that the pressure difference between the inside and outside of the quartz tube can always be controlled within the pressure difference of 0.1 MPa.

6. The method for producing high-purity red phosphorus according to claim 1, characterized in that: In the step 1, the stainless steel pipe joint extends out of the sealing head of the stainless steel sealed pressure vessel and is respectively connected to the nitrogen system and the vacuum system. The stainless steel sealed pressure vessel is also provided with a nitrogen charging and discharging port, and the nitrogen charging and discharging port is connected to the nitrogen system.

7. A method for producing high-purity red phosphorus according to claim 6, characterized in that: The nitrogen system includes a nitrogen buffer tank and a nitrogen bottle, and the vacuum system includes a vacuum buffer tank and a vacuum pump. The nitrogen bottle is connected to the nitrogen buffer tank, and the nitrogen buffer tank is respectively connected to the nitrogen charging and discharging ports and the stainless steel pipe joint through pipelines. The stainless steel pipe joint is also connected to the vacuum buffer tank in parallel. The vacuum buffer tank is connected to the exhaust buffer tank through the vacuum pump. The exhaust vacuum tank is provided with an exhaust port and a nitrogen replenishing port, and the nitrogen replenishing port is connected to the nitrogen buffer tank.

8. The method for producing high-purity red phosphorus according to claim 1, characterized in that: The wire of the infrared electric heater extends out of the stainless steel sealed pressure container and is sealed and insulated by a wire sealing and heat-insulating assembly.

Images