Process for producing red phosphorus by high-temperature closed method

Abstract

The invention relates to a process method of red phosphorus, in particular to a process for producing red phosphorus by a high-temperature closed method, which comprises the following steps: S1, preparing yellow phosphorus; s2, melting is conducted; s3, high-temperature conversion; s4, crushing; s5, alkali boiling; s6, rinsing and filtering; s7, dehydrating; s8, drying is conducted; the method for producing a slurry containing red phosphorus particles according to the present invention is advantageous in that it is a method advantageous for industrial production, it is possible to obtain a slurry containing red phosphorus particles in which phosphine gas can be generated in a short time and with stable quality, and in which the dissolution and precipitation of an oxyacid of phosphorus are reduced, and it is also possible to produce a slurry containing red phosphorus particles. According to the present invention, the red phosphorus particles obtained by a method for producing a slurry containing red phosphorus particles can be used as a raw material for production, and stabilized red phosphorus in which the amount of phosphine gas generated and the amount of oxyacid dissolution and precipitation of phosphorus are effectively suppressed can be obtained; in the whole preparation process, the labor intensity is reduced, the production efficiency is improved, and the production safety is ensured.

Description

Technical Field

[0001] The invention relates to a process for producing red phosphorus, in particular to a process for producing red phosphorus by a high-temperature closed method. Background Art

[0002] At present, the process flow of producing red phosphorus is: yellow phosphorus → melting in a pot → high temperature conversion → ball milling → alkali boiling → cleaning → centrifugal dehydration → vacuum drying → packaging and storage. The conversion principle is: the loaded yellow phosphorus is heated to about 295℃-300℃ for a long time in the case of air isolation, which can be converted into red phosphorus. After grinding, alkali boiling reaction, cleaning, dehydration and drying, the finished red phosphorus is obtained. The entire red phosphorus production process consists of conversion, ball milling, alkali boiling, washing, dehydration, drying and packaging.

[0003] The existing process for producing red phosphorus is: after melting in the conversion pot, the conversion pot is directly hoisted into the conversion furnace, the furnace cover is closed, and power is supplied for conversion. After 72 hours of conversion, it is hoisted out of the conversion furnace; then, water is added to the ball mill for wet grinding, and the material is fed to the alkali boiling high-level tank, and the slurry is sent to the alkali boiling pot. After indirectly heating to 50°C with steam under stirring, 60% sodium hydroxide solution is slowly added to remove a small amount of yellow phosphorus. Generally, after 2.5 hours, the pH value reaches 8-8.5; after the alkali boiling is completed, the slurry is placed in a cleaning tank for water washing, and then dehydrated, dried, and packaged.

[0004] The above-mentioned thermal conversion reaction is carried out by the formation, growth and combination of tiny red phosphorus nuclei. While the conversion rate increases, the formation of aggregate particles is promoted by the combination between particles. As a result, the generated red phosphorus particles rapidly coarsen and soon solidify into block-like red phosphorus.

[0005] Generally, since the solidified block red phosphorus is a coarse particle group, when it is used as a raw material for a red phosphorus flame retardant, the block red phosphorus is crushed, the particulate components are removed by a water winnowing method, etc., and the product is adjusted to the desired particle size characteristics. However, when the particulate components are removed from the red phosphorus by a water winnowing method, in order to improve the removal accuracy, not only a long processing time is required, a huge device is required, and because the sedimentation difference between large and small particles under mild conditions is used, if the water winnowing method is used to perform a continuous classification process, it is difficult to manage the operating conditions. In addition, the slurry containing the red phosphorus particles obtained in this way has the disadvantage that it is difficult to obtain a stable quality product with the particulate components removed. Summary of the invention

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: a process for producing red phosphorus by a high-temperature closed method, which comprises the following steps:

[0007] S1, yellow phosphorus is prepared by an electric furnace method, and the prepared yellow phosphorus is placed in a yellow phosphorus pool for cooling and forming to obtain a yellow phosphorus block;

[0008] S2, melting, powdering the yellow phosphorus block, then putting the yellow phosphorus into a phosphorus dissolving tank, heating it with an electric heating tube, and after the yellow phosphorus is dissolved, loading it into a conversion pot in batches, sealing the conversion pot, and loading 5-10 pots per batch;

[0009] S3, high temperature conversion, using a conversion furnace group composed of a plurality of conversion furnaces arranged in a rectangular array as equipment, putting the melted yellow phosphorus in step S2 into a vacuum drying oven for drying, and then placing the dried yellow phosphorus into a sealed conversion kettle for graded heating, the first stage heating time is 10 to 15 hours, the heating temperature is 280°C to 285°C; the second stage heating time is 7 to 9 hours, the heating temperature is 285°C to 300°C; the third stage heating time is 5 to 6 hours, the heating temperature is 350°C to 370°C; after graded high-pressure closed kettle heating reaction, the yellow phosphorus powder is converted into red phosphorus blocks;

[0010] S4, crushing, cooling the red phosphorus block obtained in step S3, using a tower mill to perform the wet crushing treatment of the first step, so that the content of red phosphorus particles with a particle size of less than 50 μm contained in the slurry is more than 50 weight % of the total amount of red phosphorus particles, and treating the prepared slurry with a liquid cyclone separator to prepare a slurry that at least reduces the content of red phosphorus particles with a particle size of less than 5 μm contained in the slurry.

[0011] S5, alkali boiling, injecting the cooled slurry into the alkali boiling tank with a non-clogging mechanical pump, and then the slurry is subjected to alkali boiling reaction in the alkali boiling tank to the alkali boiling pot for 3-4 hours;

[0012] S6, rinsing and filtering, rinsing and filtering the slurry after alkali boiling in step S5 with distilled water;

[0013] S7, dehydration, the slurry rinsed in step S6 is vacuum-pumped to remove water through a filter tank;

[0014] S8, drying, placing the red phosphorus powder that has been alkali-boiled in step S7 in a vacuum drying oven for drying, and finally obtaining a red phosphorus finished product.

[0015] As an improvement, a slurry is prepared in which the content of red phosphorus particles having a particle size of less than 5 μm is less than 5% by weight of the total amount of red phosphorus particles.

[0016] As an improvement, in the step of removing red phosphorus particles having a particle size exceeding 45 μm from the slurry, a sieve is used to remove red phosphorus particles having a particle size exceeding 50 μm.

[0017] As an improvement, the synthetic raw materials of the thermosetting resin or its initial condensate are added to the red phosphorus slurry to carry out a polymerization reaction.

[0018] As an improvement, the volume of the phosphorus dissolving tank is 10 times larger than that of the conversion pot.

[0019] The advantages of the present invention over the prior art are as follows: the method for manufacturing a slurry containing red phosphorus particles according to the present invention is a method that is beneficial to industrial production, and can obtain a slurry containing red phosphorus particles with less generation of phosphine gas and less dissolution of phosphorus oxygen acids in a short time and with stable quality, and the red phosphorus particles obtained by the method for manufacturing a slurry containing red phosphorus particles can be used as a manufacturing raw material to obtain stabilized red phosphorus with effectively suppressed generation of phosphine gas and dissolution of phosphorus oxygen acids; the entire preparation process reduces labor intensity, improves production efficiency, and ensures production safety. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] The present application fully explains the problems of the prior art in the technical background, and there are no superordinate or general problems. The problems to be solved by the present application are described in detail in the following invention content and specific implementation methods, the technical problems to be solved by the technical scheme are clarified, and it is determined that the technical scheme of the present application has beneficial effects relative to the objective prior art.

[0022] It is technically difficult to coat the surface of red phosphorus particles with a particle size of 1 μm or less contained as the microparticle component to stabilize them. In addition, it is well known that if the content of these red phosphorus particles increases, the amount of phosphine gas generated and the amount of phosphorus oxygen acid dissolved and precipitated will tend to increase (for example, refer to Patent Documents 1 to 4). An embodiment provided by the present invention:

[0023] A process for producing red phosphorus by a high-temperature closed method comprises the following steps:

[0024] S1, yellow phosphorus is prepared by an electric furnace method, and the prepared yellow phosphorus is placed in a yellow phosphorus pool for cooling and forming to obtain a yellow phosphorus block;

[0025] S2, melt, powderize the yellow phosphorus block, and then put the yellow phosphorus into the phosphorus dissolving tank, the volume of which is 10 times larger than that of the conversion pot. Use electric heating tubes for heating, and after the yellow phosphorus is dissolved, load it into the conversion pot in batches, close the conversion pot, and load 5-10 pots per batch; improve to centralized phosphorus dissolution or batch loading, firstly, reduce labor intensity and improve productivity, and secondly, greatly improve safety factor;

[0026] S3, high temperature conversion, using a conversion furnace group composed of a plurality of conversion furnaces arranged in a rectangular array as equipment, putting the melted yellow phosphorus in step S2 into a vacuum drying oven for drying, and then placing the dried yellow phosphorus into a sealed conversion kettle for graded heating, the first stage heating time is 10 to 15 hours, the heating temperature is 280°C to 285°C; the second stage heating time is 7 to 9 hours, the heating temperature is 285°C to 300°C; the third stage heating time is 5 to 6 hours, the heating temperature is 350°C to 370°C; after graded high-pressure closed kettle heating reaction, the yellow phosphorus powder is converted into red phosphorus blocks;

[0027] S4, crushing, cooling the red phosphorus block obtained in step S3, and preparing a slurry containing 5 to 60 parts by weight, preferably 10 to 55 parts by weight, of the coarse red phosphorus particles in 100 parts by weight of water. Specifically, the slurry is prepared by adding a given amount of water to the coarse red phosphorus particles;

[0028] The wet pulverizing treatment of the first step is carried out using a tower mill, which reduces labor intensity, shortens pulverizing time, avoids the generation of impurities to the greatest extent, and ensures product quality; the content of red phosphorus particles with a particle size of less than 50 μm in the slurry is made to be more than 50 weight % of the total amount of red phosphorus particles, and the prepared slurry is treated with a liquid cyclone separator to be prepared into a slurry that at least reduces the content of red phosphorus particles with a particle size of less than 5 μm in the slurry.

[0029] S5, alkali boiling, injecting the cooled slurry into the alkali boiling tank with a non-clogging mechanical pump, and then the slurry is subjected to alkali boiling reaction in the alkali boiling tank to the alkali boiling pot for 3-4 hours;

[0030] S6, rinsing and filtering, rinsing and filtering the slurry after alkali boiling in step S5 with distilled water;

[0031] S7, dehydration, the slurry rinsed in step S6 is vacuum-pumped to remove water through a filter tank;

[0032] S8, drying, placing the red phosphorus powder that has been alkali-boiled in step S7 in a vacuum drying oven for drying, and finally obtaining a red phosphorus finished product.

[0033] Preferably, a slurry is prepared in which the content of red phosphorus particles with a particle size less than 5 μm is less than 5 weight % of the total amount of red phosphorus particles; and a step of removing red phosphorus particles with a particle size exceeding 45 μm from the slurry is performed by using a sieve to remove the red phosphorus particles with a particle size exceeding 50 μm.

[0034] Preferably, a synthetic raw material of a thermosetting resin or an initial condensate thereof is added to a slurry of red phosphorus to carry out a polymerization reaction.

[0035] Preferably, the red phosphorus particles used as a raw material are coarse-grained red phosphorus particles, for example, red phosphorus in the form of blocks obtained by converting yellow phosphorus into red phosphorus by heating, wherein the content of particles with a particle size exceeding 75 μm accounts for more than 10 weight % of the total amount of the red phosphorus particles, and the content of particles with a particle size of 45 μm or less accounts for less than 50 weight % of the total amount of the red phosphorus particles. In addition, although there are no specific restrictions on other physical properties, the content of Fe contained in the red phosphorus particles, which serves as a decomposition catalyst for red phosphorus, is less than 0.1 weight %, preferably less than 0.05 weight %, and the content of yellow phosphorus, which is chemically unstable and flammable and serves as an important cause of the dissolution and precipitation of phosphorus oxygen acids and the generation of phosphine gas, is less than 0.005 weight %, preferably less than 0.002 weight %. Outside this range, these impurities can be removed by performing the following acid treatment or alkali treatment to further reduce the generation of phosphine gas and the dissolution and precipitation of phosphorus oxygen acids.

[0036] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope of the present application is indicated by the claims.

[0037] It should be understood that the present application is not limited to the above description, and various modifications and changes can be made without departing from its scope. The above-described embodiments of the present application do not constitute a limitation on the scope of protection of the present application.

Claims

1. A process for producing red phosphorus by a high-temperature closed method, characterized in that: The following steps are involved: S1, yellow phosphorus is prepared by an electric furnace method, and the prepared yellow phosphorus is placed in a yellow phosphorus pool for cooling and forming to obtain a yellow phosphorus block; S2, melting, powdering the yellow phosphorus block, then putting the yellow phosphorus into a phosphorus dissolving tank, heating it with an electric heating tube, and after the yellow phosphorus is dissolved, loading it into a conversion pot in batches, sealing the conversion pot, and loading 5-10 pots per batch; S3, high temperature conversion, using a conversion furnace group composed of a plurality of conversion furnaces arranged in a rectangular array as equipment, putting the melted yellow phosphorus in step S2 into a vacuum drying oven for drying, and then placing the dried yellow phosphorus into a sealed conversion kettle for graded heating, the first stage heating time is 10 to 15 hours, the heating temperature is 280°C to 285°C; the second stage heating time is 7 to 9 hours, the heating temperature is 285°C to 300°C; the third stage heating time is 5 to 6 hours, the heating temperature is 350°C to 370°C; after graded high-pressure closed kettle heating reaction, the yellow phosphorus powder is converted into red phosphorus blocks; S4, crushing, cooling the red phosphorus block obtained in step S3, using a tower mill to perform the wet crushing treatment of the first step, so that the content of red phosphorus particles with a particle size of less than 50 μm contained in the slurry is more than 50 weight % of the total amount of red phosphorus particles, and treating the prepared slurry with a liquid cyclone separator to prepare a slurry that at least reduces the content of red phosphorus particles with a particle size of less than 5 μm contained in the slurry. S5, alkali boiling, injecting the cooled slurry into the alkali boiling tank with a non-clogging mechanical pump, and then the slurry is subjected to alkali boiling reaction in the alkali boiling tank to the alkali boiling pot for 3-4 hours; S6, rinsing and filtering, rinsing and filtering the slurry after alkali boiling in step S5 with distilled water; S7, dehydration, the slurry rinsed in step S6 is vacuum-pumped to remove water through a filter tank; S8, drying, placing the red phosphorus powder that has been alkali-boiled in step S7 in a vacuum drying oven for drying, and finally obtaining a red phosphorus finished product.

2. The process for producing red phosphorus by a high temperature closed method according to claim 1, characterized in that: A slurry is prepared in which the content of red phosphorus particles having a particle size of less than 5 μm is 5% by weight or less of the total amount of red phosphorus particles.

3. The process for producing red phosphorus by a high temperature closed method according to claim 1, characterized in that: The step of removing red phosphorus particles having a particle size exceeding 45 μm from the slurry includes removing red phosphorus particles having a particle size exceeding 50 μm using a sieve.

4. The process for producing red phosphorus by a high temperature closed method according to claim 1, characterized in that: A synthetic raw material for a thermosetting resin or its initial condensate is added to a slurry of red phosphorus to carry out a polymerization reaction.

5. The process for producing red phosphorus by a high temperature closed method according to claim 1, characterized in that: The volume of the phosphorus dissolving tank is 10 times larger than that of the conversion pot.