A method for converting high-purity yellow phosphorus into red phosphorus

Abstract

A method for converting high-purity yellow phosphorus into red phosphorus involves first setting up a conversion system, and then using the system to convert the high-purity yellow phosphorus into red phosphorus. The conversion system includes a heating furnace (1) equipped with a heating regulator (7), a heating tank (2) for heating high-purity yellow phosphorus, a condenser (3), a receiving tank (4) with a vent valve (13), a vacuum pump (5), and an alkaline absorption tank (6). The heating tank contains a storage bottle (11) with a valve for sealing high-purity yellow phosphorus. A nitrogen input pipe (8) and a pressure gauge (9) are installed on the tank body. A tail gas pipe with a tail gas valve (12) is connected to the top cover of the heating tank. An asbestos sleeve (10) is installed between the heating tank and the storage bottle. A control valve (14) is installed on the pipeline connecting the condenser and the receiving tank. This invention can automatically convert high-purity yellow phosphorus into red phosphorus, which is safe, reliable, energy-efficient, has a high red phosphorus yield, and is clean and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the technical field of red phosphorus preparation methods, specifically to a method for converting high-purity yellow phosphorus into red phosphorus. Background Technology

[0002] High-purity phosphorus is mainly used in the preparation of III-V compound semiconductors, high-purity alloys, and germanium and silicon single crystal dopants. With the development of related materials industries, represented by semiconductor materials, especially the gallium phosphide and indium phosphide industries, the demand for high-purity phosphorus is gradually increasing. Currently, the main methods for preparing high-purity phosphorus are chlorination, distillation, and reduction. Because the high-purity yellow phosphorus (99.999% purity) obtained by the reduction reaction is solid at room temperature and has spontaneous combustion properties, for safety and quality assurance requirements, high-purity yellow phosphorus is generally stored in quartz storage bottles filled with pure water. For ease of use, yellow phosphorus must be converted into red phosphorus. Currently, there are two main methods for converting yellow phosphorus into red phosphorus. One method is the closed-loop steel pot conversion method. Yellow phosphorus is added to a sealed cast iron or steel pot and heated to a temperature slightly below 420°C using gas or electricity for several hours in the absence of air to convert it into red phosphorus. After cooling, the material in the conversion pot is a dark red to purple solid, still containing trace amounts of yellow phosphorus. After crushing, the yellow phosphorus is removed by boiling in a dilute caustic soda solution, followed by wet sieving, filtration and washing in a rotary filter, and vacuum drying to obtain the finished red phosphorus product. The other method is the ball mill converter conversion method. Before adding yellow phosphorus, the ball mill is purged with inert gas. Before the temperature reaches 180–190°C, the converter is connected to a water seal for about 2 hours to remove all water vapor. Then, under sealed conditions, the yellow phosphorus is heated to 270°C for about 20 hours. At this point, an exothermic reaction begins, and the temperature is raised to 290°C within 4 hours. After the exothermic reaction ceases, the temperature is reheated to 360℃ for approximately 5 hours. The red phosphorus contains less than 0.1% yellow phosphorus, which is removed by boiling in a dilute sodium hydroxide solution after cooling. Then, 1% magnesium oxide is added to stabilize the red phosphorus. After filtration, washing, and vacuum drying, the finished red phosphorus product is obtained. This process suffers from poor automation, high energy consumption, low yield, and environmental pollution. Therefore, developing a safe production system and method for converting yellow phosphorus to red phosphorus that is automatically controlled, energy-efficient, has a high yield, and causes minimal environmental pollution is of great significance. Summary of the Invention

[0003] The purpose of this invention is to solve the problems existing in the prior art and provide a method that can automatically convert high-purity yellow phosphorus into red phosphorus, which is safe, reliable, reduces energy consumption, increases yield, and is clean and environmentally friendly.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for converting high-purity yellow phosphorus into red phosphorus involves first setting up a conversion system, and then using the system to convert high-purity yellow phosphorus into red phosphorus.

[0006] The conversion system includes a heating furnace, a heating tank for heating high-purity yellow phosphorus connected sequentially to the heating furnace via pipelines, a condenser, a receiving tank with a vent valve, a vacuum pump, and an alkaline absorption tank. The heating furnace is equipped with a heating regulator to adjust the heating temperature. The heating tank contains a valved storage bottle for liquid-sealed high-purity yellow phosphorus. The tank body is equipped with a nitrogen input pipe and a pressure gauge. The top cover of the heating tank is externally connected to a tail gas pipe with a tail gas valve. An asbestos sleeve is installed between the heating tank and the storage bottle. A control valve is installed on the pipeline connecting the condenser and the receiving tank.

[0007] The method for converting high-purity yellow phosphorus into red phosphorus using the aforementioned system is as follows:

[0008] S1. Store high-purity yellow phosphorus in a storage bottle, open the valve of the storage bottle and place it into the heating tank, cover the top of the heating tank, open the valve, and turn on the vacuum pump and condenser. When the pressure gauge shows that the pressure reaches -0.008MPa, turn on the heating regulator and heat the heating tank through the heating furnace. Maintain the furnace temperature at 55-65℃ and run for 1-2 hours. The water in the storage bottle will begin to evaporate and enter the receiving tank, and the tail gas will enter the alkali tank.

[0009] S2. Close the tail gas valve, open the vent valve of the receiving tank, stop the vacuum pump, and introduce high-purity nitrogen into the heating tank through the nitrogen input pipe to restore the pressure of the heating tank to 0MPa;

[0010] S3. Adjust the heating regulator to slowly raise the furnace temperature to 300-350℃, until the pressure inside the heating tank reaches 0.1-0.3MPa. Maintain the temperature and pressure for 30-35 hours to obtain red phosphorus with a density greater than 70%.

[0011] The storage bottle of this invention is a quartz storage bottle. The top cover of the heating tank is a conical top cover. The high-purity yellow phosphorus is yellow phosphorus with a purity of 99.999%.

[0012] The present invention has the following advantages:

[0013] 1. The conversion system and conversion method of the present invention realize the conversion of high-purity yellow phosphorus into red phosphorus in a fully enclosed state, which is safe, reliable and automatic.

[0014] 2. The water in the storage bottle of liquid-sealed high-purity yellow phosphorus is distilled at low temperature, which not only prevents the volatilization of high-purity yellow phosphorus from corroding the equipment and reducing the weight of raw materials, thus improving the yield, but also effectively reduces energy consumption.

[0015] 3. High-purity yellow phosphorus is converted into red phosphorus by pressurization. The resulting red phosphorus product has high density and a high direct recovery rate, which can reach more than 70%, meeting the needs of synthesizing products such as indium phosphide.

[0016] 4. The exhaust gas from the vacuum pump is treated through an alkaline absorption tank and is not discharged externally to prevent environmental pollution and avoid harm to workers from toxic substances. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the conversion system described in this invention. Detailed Implementation

[0018] The invention will now be further described in conjunction with the accompanying drawings and embodiments.

[0019] A system for converting high-purity yellow phosphorus into red phosphorus, such as Figure 1 As shown, the system includes a heating furnace 1, a heating tank 2 for heating high-purity yellow phosphorus connected sequentially to the heating furnace via pipelines, a condenser 3, a receiving tank 4 with a vent valve 13, a vacuum pump 5, and an alkali absorption tank 6. The heating furnace 1 is equipped with a heating regulator 7 to adjust the heating temperature. The heating tank 2 contains a valved storage bottle 11 for liquid-sealed high-purity yellow phosphorus. A nitrogen inlet pipe 8 and a pressure gauge 9 are installed on the tank body. A tail gas pipe with a tail gas valve 12 is connected to the top cover of the heating tank, with the other end of the tail gas pipe connected to the condenser 3. An asbestos sleeve 10 is installed between the heating tank and the storage bottle, providing good protection for the storage bottle. A control valve 14 is installed on the pipeline connecting the condenser 3 and the receiving tank 4. The heating furnace and its heating regulator can be existing technology equipment. The valved storage bottle for liquid-sealed high-purity yellow phosphorus, the receiving tank, and the alkali absorption tank are all existing technology devices.

[0020] use Figure 1 The system shown converts high-purity yellow phosphorus into red phosphorus using the following method:

[0021] S1. For safety, high-purity yellow phosphorus (99.999%) is stored in a valved quartz storage bottle 11 containing pure water. The storage bottle valve is opened and placed inside the heating tank 2. The conical top cover of the heating tank is then closed, valve 12 is opened, and the vacuum pump 5 and condenser 4 are turned on. When the pressure gauge 9 shows a pressure of -0.008 MPa, the heating regulator 7 is turned on, and the heating tank 2 is heated through the heating furnace 1, maintaining the furnace temperature at 55-65℃ for 1-2 hours. The water in the storage bottle begins to slowly evaporate and enters the receiving tank 4, while the exhaust gas enters the alkali solution tank 6. This step allows the water in the storage bottle to evaporate at low temperature. The exhaust gas extracted by the vacuum pump is condensed by the condenser and collected by the receiving tank. The exhaust gas from the vacuum pump is treated through the alkali solution absorption tank and is not discharged externally to avoid environmental pollution.

[0022] S2. Close the tail gas valve 12, open the vent valve 13 of the receiving tank, and stop the vacuum pump 5 to balance the pressure in the system and prevent backflow of alkali solution from the alkali tank. Introduce high-purity nitrogen (99.999%) into the heating tank 2 through the nitrogen inlet pipe 8 to restore the pressure in the heating tank to 0 MPa, so as to avoid accelerating material volatilization under negative pressure and to prevent air from being drawn in due to pressure difference after conversion.

[0023] S3. Adjust the heating regulator 7 to slowly raise the temperature of the heating furnace to 300-350℃, until the pressure inside the heating tank 2 reaches 0.1-0.3MPa. Maintain the temperature and pressure for 30-35 hours. Under oxygen-free and slightly positive pressure conditions, high-purity yellow phosphorus is slowly heated and converted in the storage bottle to obtain red phosphorus with a density greater than 70%, which can meet the requirements for synthesizing products such as indium phosphide.

Claims

1. A method for converting high-purity yellow phosphorus into red phosphorus, characterized by, First, a conversion system is set up, and then the conversion system is used to convert high-purity yellow phosphorus into red phosphorus; The conversion system includes a heating furnace (1), a heating tank (2) for heating high-purity yellow phosphorus connected sequentially to the heating furnace (1) via pipelines, a condenser (3), a receiving tank (4) with a vent valve (13), a vacuum pump (5), and an alkaline absorption tank (6); the heating furnace (1) is equipped with a heating regulator (7) for adjusting the heating temperature, the heating tank (2) is equipped with a storage bottle (11) with a valve for sealing high-purity yellow phosphorus, the heating tank (2) is equipped with a nitrogen input pipe (8) and a pressure gauge (9), the heating tank (2) is equipped with a tail gas pipe with a tail gas valve (12) connected to the top cover of the heating tank (2), an asbestos sleeve (10) is provided between the heating tank (2) and the storage bottle (11), and a control valve (14) is provided on the pipeline connecting the condenser (3) and the receiving tank (4); The method for converting high-purity yellow phosphorus into red phosphorus using the aforementioned system is as follows: S1. Store high-purity yellow phosphorus in a storage bottle (11), open the storage bottle valve and place it in the heating tank (2), cover the top of the heating tank, open the tail gas valve (12), turn on the vacuum pump (5) and condenser (3), when the pressure gauge (9) shows that the pressure reaches -0.008MPa, turn on the heating regulator (7), heat the heating tank (2) through the heating furnace (1), keep the furnace temperature of the heating furnace (1) at 55-65℃, run for 1-2 hours, the water in the storage bottle (11) begins to evaporate and enter the receiving tank (4), and the tail gas enters the alkaline absorption tank (6); S2. Close the tail gas valve (12), open the vent valve (13) of the receiving tank (4), stop the vacuum pump (5), and introduce high-purity nitrogen into the heating tank (2) through the nitrogen input pipe (8) to restore the pressure of the heating tank (2) to 0MPa; S3. Adjust the heating regulator (7) to slowly raise the temperature of the heating furnace (1) to 300-350℃, until the pressure inside the heating tank (2) reaches 0.1-0.3MPa. Maintain the temperature and pressure for 30-35 hours to obtain red phosphorus with a density greater than 70%.

2. The method of converting high purity yellow phosphorus to red phosphorus according to claim 1, characterized in that, The storage bottle (11) is a quartz storage bottle.

3. A process for converting high-purity yellow phosphorus into red phosphorus according to claim 1 or 2, characterized in that, The top cover of the heating tank is a conical top cover.

4. The method of converting high purity yellow phosphorus to red phosphorus according to claim 1, characterized in that, The high-purity yellow phosphorus is yellow phosphorus with a purity of 99.999%.

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