CN116374970B - Purification process and device for preparing high-purity phosphorus pentasulfide - Google Patents

Abstract

The invention provides a process and a device for preparing high-purity phosphorus pentasulfide, wherein the process for preparing the high-purity phosphorus pentasulfide adopts a multi-step rectification process, and the process flow comprises the following steps: adding the crude phosphorus pentasulfide product into a multi-step rectifying device, removing various impurities such as heavy salt impurities, light sulfur phosphorus impurities, organic impurities and the like in the crude phosphorus pentasulfide product through multi-step rectification such as heavy salt removal rectification, light impurity removal rectification, organic impurity removal rectification and the like, particularly thoroughly removing the organic impurities, thereby obtaining a high-purity phosphorus pentasulfide product, recycling the separated light sulfur phosphorus impurities as sulfur or phosphorus raw materials, and intensively treating the separated heavy salt impurities and organic impurities as wastes. The device mainly comprises a synthetic feeding device, a multi-step rectifying device, a rectifying component storage device and the like. The invention can effectively improve the purification effect of the coarse phosphorus pentasulfide product, especially can reduce the content of organic impurities, and can obtain the high-purity phosphorus pentasulfide product.

Description

A purification process and device for preparing high-purity phosphorus pentasulfide

Technical Field

The present invention belongs to the technical field of phosphorus pentasulfide production, and in particular relates to a purification process and device for preparing high-purity phosphorus pentasulfide.

Background technique

Phosphorus pentasulfide [P ₂ S ₅ , also known as tetraphosphorus decasulfide (P ₄ S ₁₀ )] is widely used in pesticides (dimethoate, phoxim, ethyl 1605, etc.), lubricant additives, non-ferrous metal flotation agents and pharmaceutical industries, especially lubricant grade (superior grade and above) high-purity phosphorus pentasulfide products, which have very important uses, are in great demand and have very good market prospects.

The purity of phosphorus pentasulfide products is not only related to the content of phosphorus pentasulfide components in the product, but also to the sulfur and phosphorus elements and their polysulfides ( _P4Sx , _x =2,3,5,6,7,9), heavy salts [mainly sulfur-containing salts (such as calcium sulfide, etc.), phosphorus-containing salts (such as calcium phosphate, etc.), sulfur-phosphorus complex salts (thiophosphates, etc.), calcium sulfate] and organic impurities [see national standard GB/T 13258-2016 (Industrial Phosphorus Pentasulfide)]. Organic impurities, in particular, have a great influence on the quality of phosphorus pentasulfide products. When the content of organic impurities exceeds 0.3%, the color and physical properties of phosphorus pentasulfide will change significantly and the quality will deteriorate, which seriously limits the application of phosphorus pentasulfide. For example, when phosphorus pentasulfide is used in the lubricating oil industry, the organic impurities cannot exceed 0.1%.

Therefore, if a high-purity phosphorus pentasulfide product is to be obtained, the crude phosphorus pentasulfide product produced by synthesis must be purified to remove impurities such as phosphorus polysulfide, phosphorus salts, sulfur salts, and especially organic impurities.

At present, the purification of crude phosphorus pentasulfide products mainly adopts distillation technology. The existing distillation technology used for phosphorus pentasulfide can be divided into normal pressure simple distillation technology and reduced pressure distillation technology according to different operating pressures.

Atmospheric pressure simple distillation technology is to purify the crude product under normal pressure (or slightly positive pressure) and high temperature (about 515 ℃) to obtain high-purity phosphorus pentasulfide product, such as patent 200610019731.6. This type of technical process is relatively simple and is operated at normal pressure. It is easy to operate and has low air tightness requirements for equipment. However, the distillation purification effect is poor, impurities such as polysulfide are not completely removed, and the product quality is poor. In particular, it is difficult to remove organic impurities, and the distillation temperature is high, and the energy consumption is also high.

The vacuum distillation technology is to purify the crude product under negative pressure (20 KPaA or lower) and relatively low temperature (about 380 °C) to obtain a high-purity phosphorus pentasulfide product, such as patents CN101712464A, 200810233489.1, CN101844755A and CN101402450B. Compared with simple distillation at normal pressure, vacuum distillation has a lower distillation temperature, lower energy consumption, higher content of phosphorus pentasulfide components, and better product quality. However, it is also impossible to completely remove organic impurities, which seriously affects the purity and quality of the phosphorus pentasulfide product.

In addition, the impurity composition of the crude phosphorus pentasulfide product is very complex and difficult to separate. It contains unreacted elemental sulfur, elemental phosphorus and by-product polysulfide phosphides ( _{P4Sx ,} x=2,3,5,6,7,9), heavy salt impurities with higher boiling points [mainly sulfur-containing salts (such as calcium sulfide, etc.), phosphorus-containing salts (such as calcium phosphate, etc.), sulfur-phosphorus complex salts (thiophosphates, etc.), calcium sulfate], and organic impurities. It is difficult to remove so many impurities, especially organic impurities, through a single distillation.

Therefore, it is of great significance to develop a purification technology that can deeply remove impurities, especially organic impurities, from the product to obtain high-purity phosphorus pentasulfide.

Summary of the invention

Due to the complex physical properties of crude phosphorus pentasulfide, high melting and boiling points, and toxic, flammable and explosive properties, separation and processing requires almost all of the harsh chemical process technologies, such as high-temperature operation and molten salt heat exchange. The processing technology is difficult, energy consumption is high, and accident prevention requirements are high. Compared with distillation technology, rectification technology is more complex, more difficult to implement, has higher energy consumption, and higher equipment investment and operating costs. Therefore, the combination of the purification of phosphorus pentasulfide, which has high requirements for separation and treatment, and the distillation technology, which has higher technical implementation difficulty and more complex technology, has high technical difficulty in implementation, which basically exceeds the current technical level of phosphorus pentasulfide separation and treatment, and the investment is also high. Under the condition of low product quality requirements and the lowest possible cost operation, distillation with low technical difficulty, low investment and low cost is generally used instead of distillation. However, when higher requirements are placed on product purity and quality, such as achieving a phosphorus pentasulfide product with a purity of more than 99.0wt%, a total impurity content of less than 0.4wt%, of which the organic impurity content is less than 0.1wt%, a phosphorus content of more than 28.0%, and a sulfur content of more than 71.0%, which meets the requirements of the superior high-purity phosphorus pentasulfide product specified in the National Standard of the People's Republic of China "Industrial Phosphorus Pentasulfide" (GB/T13258-2016), the traditional distillation technology cannot meet the requirements, and it is necessary to use a more advanced distillation technology with better separation effect.

In view of the shortcomings of the prior art, the object of the present invention is to provide a process and an apparatus for preparing high-purity phosphorus pentasulfide. The present invention adopts a distillation method to purify a crude product to obtain high-purity phosphorus pentasulfide, which not only increases the content of phosphorus pentasulfide in the product, but also reduces the content of impurities such as polysulfide phosphides, especially can completely remove organic impurities, and can produce a high-purity phosphorus pentasulfide product with low organic impurities.

In a first aspect, the present invention provides a purification process for preparing high-purity phosphorus pentasulfide.

Among them, the impurities in the crude product of phosphorus pentasulfide are very numerous and complex, containing heavy salt impurities with higher boiling points than phosphorus pentasulfide [mainly sulfur-containing salts (such as calcium sulfide, etc.), phosphorus-containing salts (such as calcium phosphate, etc.), sulfur-phosphorus complex salts (thiophosphates, etc.), calcium sulfate and other high-boiling impurities with higher boiling points than phosphorus pentasulfide], light sulfur-phosphorus impurities with lower boiling points than phosphorus pentasulfide [mainly polysulfur phosphides, elemental phosphorus (white phosphorus), elemental sulfur (sulfur), etc.], and organic impurities with lower boiling points than phosphorus pentasulfide. Most of the organic impurities are elemental sulfur, the raw material required in the synthesis of phosphorus pentasulfide, and organic matter with a boiling point of 150-280 ℃ carried by elemental sulfur.

The content of pure phosphorus pentasulfide in the crude phosphorus pentasulfide product is generally 85-90 wt.%;

The impurity content of heavy salts with higher boiling points than phosphorus pentasulfide is generally 3-5 wt.%, and its boiling point is 520-550 °C;

The impurity content of light sulfur phosphorus, which has a lower boiling point than phosphorus pentasulfide, is generally 5-8 wt.%, and its boiling point is 286-510 °C;

The content of organic impurities with a lower boiling point than phosphorus pentasulfide is generally 2-4 wt.%, and its boiling point is 120-280 °C.

Based on the physical properties of crude phosphorus pentasulfide, which has many impurity components and complex composition, this process uses a multi-step distillation purification process to purify the crude phosphorus pentasulfide product to obtain high-purity phosphorus pentasulfide. The specific process flow is as follows.

The crude product of phosphorus pentasulfide is added to a multi-step distillation device in a certain phase form for purification. First, heavy salt removal distillation is performed. At a certain temperature and pressure, the crude product is distilled and separated into heavy components mainly composed of heavy salt impurities with higher boiling points than phosphorus pentasulfide and light components mainly composed of phosphorus pentasulfide and light sulfur impurities with lower boiling points than phosphorus pentasulfide and organic impurities, and the impurities are discharged.

The discharged heavy components (mainly heavy salt impurities) of the heavy salt removal distillation are treated as waste in a centralized manner.

The discharged light components (mainly phosphorus pentasulfide, light sulfur phosphorus impurities and organic impurities) of the heavy salt removal distillation are subjected to light impurity removal distillation. Under a certain temperature and pressure, the light components of the heavy salt removal distillation are separated by distillation into heavy components mainly composed of phosphorus pentasulfide and light impurity components mainly composed of light sulfur phosphorus impurities and organic impurities and are discharged.

The heavy components of the distillation for removing light impurities mainly containing phosphorus pentasulfide are recovered as phosphorus pentasulfide product.

The discharged light components (mainly light sulfur and phosphorus impurities and organic impurities) of the light impurity removal distillation are subjected to organic impurity removal distillation. Under a certain temperature and pressure, the light components of the light impurity removal distillation are separated by distillation into heavy components mainly composed of light sulfur and phosphorus impurities and light components mainly composed of organic impurities and discharged.

The discharged heavy components (mainly light sulfur and phosphorus impurities) from the removal of organic impurities distillation are returned to the phosphorus pentasulfide synthesis unit as sulfur and phosphorus raw materials for reuse, while the discharged light components (mainly organic impurities) from the removal of organic impurities distillation are treated as waste in a centralized manner.

Various impurities, especially organic impurities, in the crude phosphorus pentasulfide product are removed by multiple distillation steps such as heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation to obtain a high-purity phosphorus pentasulfide product, and sulfur- or phosphorus-containing impurities such as polysulfide phosphides, elemental phosphorus and elemental sulfur in the impurities can be recycled as sulfur and phosphorus raw materials.

Among them, during the distillation feeding, the crude phosphorus pentasulfide product can be in gaseous state or in liquid state.

The multi-step distillation may be atmospheric distillation, vacuum distillation, or a combination of atmospheric distillation and vacuum distillation, with vacuum distillation being preferred.

Among them, in atmospheric distillation, vacuum distillation or a combination of atmospheric distillation and vacuum distillation, the distillation pressure should be as low as possible to reduce the boiling point of the corresponding distillation temperature, thereby reducing the distillation operating temperature.

That is, when it is atmospheric distillation, the distillation pressure is zero pressure (gauge pressure) or slightly positive pressure. Preferably, the operating pressure of atmospheric distillation is 100-110 KPaA.

When vacuum distillation is used, the distillation pressure is absolute zero pressure (absolute vacuum) or slightly greater than absolute zero pressure (high vacuum). Preferably, the operating pressure of vacuum distillation is 10-20 KPaA.

Correspondingly, whether it is atmospheric distillation or vacuum distillation, the distillation temperature is determined by the distillation physical properties (boiling point) and the operating pressure. That is, the distillation operating temperature is the boiling point temperature of the distillation light component corresponding to the operating pressure.

In the heavy salt removal distillation stage, the light impurity removal distillation stage and the organic impurity removal distillation stage, the light components are respectively a mixture of phosphorus pentasulfide and materials with a boiling point lower than phosphorus pentasulfide, a mixture of materials with a boiling point lower than phosphorus pentasulfide, and organic impurities. In these three distillation sections, the operating temperatures are the boiling points of the corresponding mixtures.

The multi-step distillation may be batch distillation or continuous distillation, and continuous distillation is preferred.

In the multi-step distillation, the crude phosphorus pentasulfide product feed can be in gaseous form or in liquid form, preferably in liquid form.

The multi-step distillation mainly includes the steps of heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation, etc., which can be carried out step by step according to the above step sequence, or according to the steps of light impurity removal distillation, organic impurity removal distillation and heavy salt removal distillation, or the steps of organic impurity removal distillation, light impurity removal distillation and heavy salt removal distillation, or other step sequences. It is preferably carried out in sequence according to the steps of heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation.

On the other hand, the present invention provides a purification device required for realizing the process of preparing high-purity phosphorus pentasulfide, and the device mainly comprises: a feeding device, a multi-step distillation device, and a distillation component storage device. Among them, the multi-step distillation device mainly comprises a heavy salt removal distillation device, a sulfur phosphorus removal distillation device, and an organic impurity removal distillation device. The distillation component storage device mainly comprises a heavy salt impurity storage device, a high-purity phosphorus pentasulfide product storage device, a light sulfur phosphorus impurity storage device, and an organic impurity storage device.

The feeding equipment can be gaseous feeding equipment or liquid feeding equipment, the feeding port of which is connected to the phosphorus pentasulfide synthesis system, and the discharging port of which is connected to the feeding port of the multi-step distillation equipment.

The multi-step distillation equipment mainly includes a heavy salt removal distillation equipment, a light impurity removal distillation equipment and an organic impurity removal distillation equipment, wherein the feed port is connected to the feed port of the feed equipment, and the heavy salt impurity outlet, phosphorus pentasulfide outlet, light sulfur phosphorus impurity outlet and organic impurity outlet are respectively connected to the heavy salt impurity inlet, phosphorus pentasulfide inlet, light sulfur phosphorus impurity inlet and organic impurity inlet of the distillation component storage device.

Among them, the multi-step distillation equipment mainly includes heavy salt removal distillation equipment, light impurity removal distillation equipment and organic impurity removal distillation equipment. The multi-step distillation equipment can be an integrated equipment in which the heavy salt removal distillation equipment, the light impurity removal distillation equipment and the organic impurity removal distillation equipment are integrated, or it can be a combined equipment in which the heavy salt removal distillation equipment, the light impurity removal distillation equipment and the organic impurity removal distillation equipment are independently dispersed, and the combined equipment is optimized.

The heavy salt removal distillation equipment, light impurity removal distillation equipment and organic impurity removal distillation equipment constituting the multi-step distillation equipment can be atmospheric pressure distillation equipment or vacuum pressure distillation equipment, preferably vacuum pressure distillation equipment.

The heavy salt removal distillation equipment, light impurity removal distillation equipment and organic impurity removal distillation equipment constituting the multi-step distillation equipment can be intermittent distillation equipment or continuous distillation equipment, preferably continuous distillation equipment.

The heavy salt removal distillation equipment, light impurity removal distillation equipment and organic impurity removal distillation equipment constituting the multi-step distillation equipment can be packed distillation equipment, can be tower plate distillation equipment, and can also be a combined packing and tower plate distillation equipment, preferably a packed distillation equipment.

Compared with the distillation purification technology used in the existing high-purity phosphorus pentasulfide production, the present invention adopts a multi-step distillation method. Due to the use of distillation technology, its separation and purification effect is much better than distillation, and the distillation is carried out in multiple steps, and the components are separated one by one, which enhances the separation effect. Therefore, the technology of the present invention can remove impurities in the crude phosphorus pentasulfide product step by step, with good removal effect, especially can completely remove organic impurities, to achieve organic impurities below 0.1%, greatly improve the purity of phosphorus pentasulfide products, the product quality is good, and can meet the needs of industries such as the lubricating oil industry that have higher requirements for the quality of phosphorus pentasulfide products.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a purification process for preparing high-purity phosphorus pentasulfide, 1: feeding equipment, 1-1: feeding equipment outlet, 2: multi-step distillation equipment, 2A: heavy salt removal distillation equipment, 2B: light impurity removal distillation equipment, 2C: organic impurity removal distillation equipment, 2-1: multi-step distillation equipment feeding port, 2-2: multi-step distillation equipment heavy salt impurity outlet, 2-3: multi-step distillation equipment phosphorus pentasulfide outlet, 2-4: multi-step distillation equipment light sulfur phosphorus impurity outlet, 2-5: multi-step distillation equipment organic impurity outlet, 3: distillation component storage equipment, 3A: heavy salt storage equipment, 3B: high-purity phosphorus pentasulfide storage equipment, 3C: light sulfur phosphorus impurity storage equipment, 3D: organic impurity storage equipment, 3-1: distillation component storage equipment heavy salt impurity inlet, 3-2: distillation component storage equipment phosphorus pentasulfide inlet, 3-3: The distillation component storage device enters the light sulfur phosphorus impurity port, 3-4: the distillation component storage device enters the organic impurity port.

FIG2 is another schematic diagram of a purification process for preparing high-purity phosphorus pentasulfide, 1: feed equipment, 1-1: feed equipment outlet, 2: multi-step distillation equipment, 2A: heavy salt removal distillation equipment, 2B: light impurity removal distillation equipment, 2C: organic impurity removal distillation equipment, 2-1: multi-step distillation equipment feed inlet, 2-2: multi-step distillation equipment outlet for heavy salt impurities, 2-3: multi-step distillation equipment outlet for phosphorus pentasulfide, 2-4: multi-step distillation equipment outlet for light sulfur phosphorus impurities, 2-5: multi-step distillation equipment outlet for organic impurities, 3: distillation component storage equipment, 3A: heavy salt storage equipment, 3B: high-purity phosphorus pentasulfide storage equipment, 3C: light sulfur phosphorus impurity storage equipment, 3D: organic impurity storage equipment, 3-1: distillation component storage equipment inlet for heavy salt impurities, 3-2: distillation component storage equipment inlet for phosphorus pentasulfide, 3-3: The distillation component storage device enters the light sulfur phosphorus impurity port, 3-4: the distillation component storage device enters the organic impurity port, a: crude phosphorus pentasulfide product, b: heavy salt impurities, c: high-purity phosphorus pentasulfide, d: light sulfur phosphorus impurities, e: organic impurities.

FIG3 is a schematic diagram of another process flow for preparing high-purity phosphorus pentasulfide, 1: feeding equipment, 1-1: feeding equipment outlet, 2: multi-step distillation equipment, 2A: heavy salt removal distillation equipment, 2B: light impurity removal distillation equipment, 2C: organic impurity removal distillation equipment, 2-1: multi-step distillation equipment feeding port, 2-2: multi-step distillation equipment outlet for heavy salt impurities, 2-3: multi-step distillation equipment outlet for phosphorus pentasulfide, 2-4: multi-step distillation equipment outlet for light sulfur phosphorus impurities, 2-5: multi-step distillation equipment outlet for organic impurities, 2-6: outlet for light components of heavy salt removal distillation equipment, 2-7: feeding port of light impurity removal distillation equipment, 2-8: outlet for light components of light impurity removal distillation equipment, 2-9: feeding port of organic impurity removal distillation equipment, 3: distillation component storage equipment, 3A: heavy salt storage equipment, 3B: High-purity phosphorus pentasulfide storage equipment, 3C: light phosphorus pentasulfide impurity storage equipment, 3D: organic impurity storage equipment, 3-1: distillation component storage equipment inlet for heavy salt impurities, 3-2: distillation component storage equipment inlet for phosphorus pentasulfide, 3-3: distillation component storage equipment inlet for light phosphorus pentasulfide impurities, 3-4: distillation component storage equipment inlet for organic impurities. a: crude phosphorus pentasulfide product, b: heavy salt impurities, c: high-purity phosphorus pentasulfide, d: light phosphorus pentasulfide impurities, e: organic impurities.

Detailed ways

As shown in Figure 1, the process flow is as follows:

The crude phosphorus pentasulfide product a is fed into a multi-step distillation device 2 in a certain phase form through a feed device 1 for purification. First, a heavy salt removal distillation is performed. At a certain temperature and pressure, the crude product a is distilled and separated into a heavy component mainly composed of a heavy salt impurity b with a higher boiling point than phosphorus pentasulfide and a light component mainly composed of phosphorus pentasulfide c and light sulfur impurities d with a lower boiling point than phosphorus pentasulfide and organic impurities e and the like, and the components are discharged.

The heavy components (mainly heavy salt impurities b) of the heavy salt removal distillation discharged from the multi-step distillation device 2 are collected by the distillation component storage device 3 and collected as waste for centralized treatment.

The light components (mainly phosphorus pentasulfide c, light sulfur phosphorus impurities d and organic impurities e) discharged from the multi-step distillation equipment 2 are subjected to light impurity removal distillation. At a certain temperature and pressure, the light components of the heavy salt removal distillation are distilled and separated into heavy components mainly composed of phosphorus pentasulfide c and light impurity components mainly composed of light sulfur phosphorus impurities d and organic impurities e, and are discharged.

The heavy components of the light impurity removal distillation, mainly phosphorus pentasulfide c, are discharged from the multi-step distillation device 2 and collected by the distillation component storage device 3 and recovered as phosphorus pentasulfide product.

The discharged light components of the light impurity removal distillation (mainly light sulfur and phosphorus impurities d and organic impurities e) are subjected to organic impurity removal distillation. At a certain temperature and pressure, the light components of the light impurity removal distillation are distilled and separated into heavy components mainly composed of light sulfur and phosphorus impurities d and light components mainly composed of organic impurities e and are discharged.

The discharged heavy components (mainly light sulfur and phosphorus impurities) of the organic impurity removal distillation are discharged from the multi-step distillation equipment 2, collected by the distillation component storage equipment 3 and returned to the phosphorus pentasulfide synthesis unit as sulfur and phosphorus raw materials for reuse, while the discharged light components (mainly organic impurities) of the organic impurity removal distillation are discharged from the multi-step distillation equipment 2, collected by the distillation component storage equipment 3 and treated as waste in a centralized manner.

Various impurities, especially organic impurities, in the crude phosphorus pentasulfide product are removed by multiple distillation steps such as heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation to obtain a high-purity phosphorus pentasulfide product, and sulfur- or phosphorus-containing impurities such as polysulfide phosphides, elemental phosphorus and elemental sulfur in the impurities can be recycled as sulfur and phosphorus raw materials.

Among them, during the distillation feeding, the crude phosphorus pentasulfide product can be in gaseous state or in liquid state.

The multi-step distillation may be batch distillation or continuous distillation, and continuous distillation is preferred.

In the multi-step distillation, the phosphorus pentasulfide product feed can be in gaseous form or in liquid form, preferably in liquid form.

The multi-step distillation in the above steps mainly includes the steps of heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation, etc., which can be carried out step by step in the above step sequence, or in the steps of light impurity removal distillation, organic impurity removal distillation and heavy salt removal distillation, or in the order of organic impurity removal distillation, light impurity removal and heavy salt removal distillation, or other step sequences. It is preferably carried out in the order of heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation.

The content of pure phosphorus pentasulfide in the crude phosphorus pentasulfide product is generally 85-90 wt.%, the content of heavy salt impurities with a boiling point of 520-550°C is generally 3-5 wt.%, the content of light sulfur impurities with a boiling point of 286-510°C is generally 5-8 wt.%, and the content of organic impurities with a boiling point of 120-280°C is generally 2-4 wt.%.

The multi-step distillation may be atmospheric distillation, vacuum distillation, or a combination of atmospheric distillation and vacuum distillation, with vacuum distillation being preferred.

Among them, in atmospheric distillation, vacuum distillation or a combination of atmospheric distillation and vacuum distillation, the distillation pressure should be as low as possible to reduce the boiling point of the corresponding distillation temperature, thereby reducing the distillation operating temperature.

That is, when it is atmospheric distillation, the distillation pressure is zero pressure (gauge pressure) or slightly positive pressure. Preferably, the operating pressure of atmospheric distillation is 100-110 KPaA.

When vacuum distillation is used, the distillation pressure is absolute zero pressure (absolute vacuum) or slightly greater than absolute zero pressure (high vacuum). Preferably, the operating pressure of vacuum distillation is 10-20 KPaA.

Correspondingly, whether it is atmospheric distillation or vacuum distillation, the distillation temperature is determined by the distillation physical properties (boiling point) and the operating pressure. That is, the distillation operating temperature is the boiling point temperature of the distillation light component corresponding to the operating pressure.

In the heavy salt removal distillation stage, the light impurity removal distillation stage and the organic impurity removal distillation stage, the light components are respectively phosphorus pentasulfide and a mixture of materials with a boiling point lower than phosphorus pentasulfide, a mixture of materials with a boiling point lower than phosphorus pentasulfide, and organic impurities. In these three distillation sections, the operating temperatures are the boiling points of the corresponding mixtures, specifically:

In atmospheric distillation, when the distillation temperature is 520-550°C, the separation of the mixture consisting of heavy salt impurities and phosphorus pentasulfide and materials with a boiling point lower than phosphorus pentasulfide is achieved; further, when the distillation temperature is 286-510°C, the separation of phosphorus pentasulfide and a mixture consisting of materials with a boiling point lower than phosphorus pentasulfide (specifically light phosphorus pentasulfide impurities and organic impurities) is achieved; further, when the distillation temperature is 120-280°C, the separation of light phosphorus pentasulfide impurities and organic impurities is achieved.

In the vacuum distillation, at 10-20KPaA, when the distillation temperature is 390-430°C, the separation of the mixture consisting of heavy salt impurities and phosphorus pentasulfide and materials with a boiling point lower than phosphorus pentasulfide is achieved; further, when the distillation temperature is 190°C-380°C, the separation of phosphorus pentasulfide and a mixture consisting of materials with a boiling point lower than phosphorus pentasulfide (specifically light phosphorus pentasulfide impurities and organic impurities) is achieved; further, when the distillation temperature is 60-160°C, the separation of light phosphorus pentasulfide impurities and organic impurities is achieved.

Compared with the traditional distillation technology, the technical solution of the present invention adopts the distillation technology with better separation effect. The separation effect of distillation is better than that of distillation because a) distillation is a special form of distillation, which is equivalent to multi-stage distillation; b) distillation has only a stripping section, while distillation has not only a stripping section, but also a distillation section, which enhances the separation effect; c) distillation has reflux and reheating, which can generate steam in the lower part and realize reverse exchange with the liquid condensed and refluxed by the upper steam, and this exchange can be carried out many times, which greatly enhances the gas-liquid mass transfer effect, so that the clear components in the liquid phase can enter the gas phase more thoroughly, and enhance the separation effect. Distillation adopts multi-step distillation to gradually separate the components in the crude product one by one, which enhances the separation effect.

Example 1

Based on the above process introduction, this embodiment is described in detail by taking the continuous atmospheric distillation purification of gaseous feed in an integrated multi-step distillation device as an example. The process flow and the purification device used are shown in FIG2 .

The purification device used in this embodiment mainly includes: a feed device 1, a multi-step distillation device 2, and a distillation component storage device 3. The multi-step distillation device used is a baffle plate distillation tower.

The feeding device 1 is a centrifugal gas delivery pump, which mainly supplies crude phosphorus pentasulfide product to the multi-step distillation device, and its discharge port 1-1 is connected to the feeding port 2-1 of the multi-step distillation device 2.

The multi-step distillation equipment 2 is an integrated baffle plate distillation tower, which is mainly used for distilling and purifying crude phosphorus pentasulfide products. The lower part of the distillation tower body is divided into two zones by a baffle. The side close to the feed inlet is the light impurity removal distillation equipment (section) 2B, and the other side is the heavy salt removal distillation equipment (section) 2A. The upper part of the distillation tower is the organic impurity removal distillation equipment (section) 2C.

The lower part of the tower kettle of the multi-step distillation equipment 2 is provided with a heavy salt impurity outlet 2-2, which is connected to the heavy salt impurity inlet of the distillation component storage device 3; the tower top of the multi-step distillation equipment 2 is provided with an organic impurity outlet 2-5, which is connected to the organic impurity inlet 2-5 of the distillation component storage device 3; the side wall of the heavy salt removal distillation equipment (section) 2A of the multi-step distillation equipment 2 is provided with a phosphorus pentasulfide outlet 2-3, which is connected to the phosphorus pentasulfide inlet 2-3 of the distillation component storage device 3; the side wall of the organic impurity removal equipment (section) 2C of the multi-step distillation equipment 2 is provided with a light sulfur phosphorus impurity outlet 2-4, which is connected to the light sulfur phosphorus impurity inlet 2-3 of the distillation component storage device 3.

The distillation component storage device 3 mainly includes a heavy salt storage device 3A, a high-purity phosphorus pentasulfide storage device 3B, a light phosphorus sulfur impurity storage device 3C, and an organic impurity storage device 3D.

The heavy salt impurity inlet 3-1 of the distillation component storage device 3 is connected to the heavy salt impurity outlet 2-2 of the multi-step distillation device 2, so as to transport the heavy salt impurities to the heavy salt impurity storage device 3A; the phosphorus pentasulfide inlet 3-2 of the distillation component storage device 3 is connected to the phosphorus pentasulfide outlet 2-3 of the multi-step distillation device 2, so as to transport the phosphorus pentasulfide to the phosphorus pentasulfide storage device 3B; the light phosphorus sulfur impurity inlet 3-3 of the distillation component storage device 3 is connected to the light phosphorus sulfur impurity outlet 2-4 of the multi-step distillation device 2, so as to transport the light phosphorus sulfur impurities to the light phosphorus sulfur impurity storage device 3C; the organic impurity inlet 3-4 of the distillation component storage device 3 is connected to the organic impurity inlet 2-5 of the multi-step distillation device 2, so as to transport the organic impurities to the organic impurity inlet 3D.

A gaseous crude phosphorus pentasulfide product a is supplied to a multi-step distillation device 2 with a tower top pressure of 110 KPaA by means of a feeding device 1 at a feeding rate of 1 t/h. The crude phosphorus pentasulfide product has a temperature of 570°C and a boiling point of 510°C. Its composition is as follows: the content of pure phosphorus pentasulfide with a boiling point of 515°C is 90 wt.%, the content of heavy salt impurities with a boiling point of 520-550°C is 3 wt.%, the content of light sulfur phosphorus impurities with a boiling point of 286-510°C is 5 wt.%, and the content of organic impurities with a boiling point of 120-280°C is 2 wt.%.

After the crude phosphorus pentasulfide product a enters the multi-step distillation device 2, it exchanges heat and mass with the liquid coming down from the organic impurity removal distillation device (section) 2C of the multi-step distillation device 2 to cool down, and the light sulfur phosphorus impurities d and organic impurities e with lower boiling points in the crude phosphorus pentasulfide product a rise in the form of a gas mixture and enter the organic impurity removal device (section) 2C, while the phosphorus pentasulfide c and heavy salt impurities b with higher boiling points enter the tower bottom in the form of a liquid mixture.

The mixed gas of light sulfur phosphorus impurity c and organic impurity d entering the organic impurity removal device (section) 2C exchanges heat and mass with the liquid material coming down from the upper part of the organic impurity removal device (section) 2C to cool down. When the temperature drops to about 286°C, the main component of the mixed gas with a higher boiling point, light sulfur phosphorus impurity d, begins to liquefy and is discharged from the light sulfur phosphorus impurity outlet 2-4 located on the side wall of the organic impurity removal device (section) 2C, thereby separating the light sulfur phosphorus impurity d from the mixed gas of light sulfur phosphorus impurity c and organic impurity d. Among them, the discharge amount of the discharged light sulfur phosphorus impurity d is 0.049 t/h, and the contents of pure light sulfur phosphorus impurity, organic impurities, pure phosphorus pentasulfide and heavy salt impurities are 93 wt.%, 1 wt.%, 5.5 wt.% and 0.5 wt.%, respectively, and the recovery rate of light sulfur phosphorus impurities is 91.14%.

The material mainly composed of light phosphorus pentasulfide impurities d discharged from the light phosphorus pentasulfide impurity outlet 2-4 enters the light phosphorus pentasulfide impurity storage device of the distillation component storage device 3 through the light phosphorus pentasulfide impurity inlet 3-3 for storage 3C, and is returned to the phosphorus pentasulfide synthesis system for reuse as sulfur or phosphorus raw material.

After the light sulfur phosphorus impurity d is separated, the remaining gas, which is mainly composed of organic impurities e, continues to rise and cool down. When the temperature drops to 280°C, it is discharged from the top of the tower. After condensation treatment, it is discharged from the organic impurity outlet 2-5 at the top of the tower in the form of a liquid with a temperature of 280°C.

The material mainly composed of organic impurities e discharged from the organic impurity outlet 2-5 enters the organic impurity storage device 3D of the distillation component storage device 3 through the organic impurity inlet 3-4 for storage so as to be centrally processed.

The gas mainly composed of organic impurities e with a lower boiling point in the mixed gas continues to rise and cool down. When the temperature drops to 280°C, it is discharged from the top of the tower. After condensation, it is discharged from the organic impurity outlet 2-5 at the top of the tower in the form of liquid with a temperature of 280°C. The light sulfur phosphorus impurity d with a higher boiling point is liquefied due to the drop in temperature and enters the tower kettle in the form of a very small amount of diphosphorus pentasulfide c and heavy salt impurities b.

The mixture of phosphorus pentasulfide c and heavy salt impurity b that is cooled and liquefied in the light impurity removal distillation device (section) 2B of the multi-step distillation device 2 and flows into the tower kettle is reheated to about 520°C and vaporized and enters the heavy salt removal distillation device (section) 2A, where it exchanges heat and mass with the liquid coming down from the upper part to cool down, wherein the material mainly composed of heavy salt impurity b with a higher boiling point is reliquefied and enters the tower kettle and exits from the heavy salt impurity outlet 2-1 located at the bottom of the tower kettle, while the pure phosphorus pentasulfide with a lower boiling point continues to rise in the form of gas and cools down. When the temperature drops to 515°C, the material mainly composed of phosphorus pentasulfide c is discharged from the phosphorus pentasulfide outlet located on the side wall of the heavy salt removal distillation device (section) 2A, thereby separating phosphorus pentasulfide and heavy salt impurities.

The discharge rate of the material mainly composed of phosphorus pentasulfide c discharged from the phosphorus pentasulfide outlet located on the side wall of the heavy salt removal distillation equipment (section) 2A is 0.89 t/h. The contents of phosphorus pentasulfide, organic impurities, light sulfur phosphorus impurities and heavy salt impurities are 99.5 wt.%, 0.05 wt.%, 0.25 wt.% and 0.1 wt.%, respectively. The recovery rate of phosphorus pentasulfide components reaches 88.56%, of which the phosphorus content is 28.1% and the sulfur content is 71.85%. The phosphorus pentasulfide storage device 3B of the distillation component storage device 3 is stored as a high-purity phosphorus pentasulfide product through the phosphorus pentasulfide inlet.

The material mainly composed of heavy salt impurities b discharged from the heavy salt impurity outlet at the bottom of the tower is entered into the heavy salt impurity storage device 3A of the distillation component storage device 3 through the heavy salt impurity inlet 2-2 for storage for centralized processing.

Through this embodiment, the crude product of phosphorus pentasulfide can be distilled and separated into phosphorus pentasulfide product, light sulfur phosphorus impurities, heavy salt impurities and organic impurities. The contents of phosphorus pentasulfide, organic impurities, light sulfur phosphorus impurities and heavy salt impurities in the obtained phosphorus pentasulfide product are 99.5 wt.%, 0.05 wt.%, 0.25 wt.% and 0.1 wt.%, respectively, the phosphorus content is 28.1%, and the sulfur content is 71.85%, which meets the requirements of the superior high-purity phosphorus pentasulfide product specified in the National Standard of the People's Republic of China "Industrial Phosphorus Pentasulfide" (GB/T13258-2016), and the organic impurity content is low, which is 0.05 wt.%, and meets the quality requirements of phosphorus pentasulfide products in industries such as lubricating oil manufacturing that have high requirements for phosphorus pentasulfide products, and the recovery rate of phosphorus pentasulfide components is 88.55%, and the recovery rate of phosphorus pentasulfide components is high. At the same time, 91.14% of the light sulfur phosphorus impurities can be recovered, and the recovery rate is high.

Example 2

Based on the above process introduction, this embodiment is described in detail by taking the intermittent reduced pressure distillation purification method of liquid feed in a multi-device combined distillation device as an example. The process flow and the purification device used are shown in Figure 3.

The purification device used in this embodiment mainly includes: a feed device 1, a multi-step distillation device 2, and a distillation component storage device 3. Among them, the multi-step distillation device used is a multi-device combined distillation device.

The feeding device 1 is a liquid delivery pump, which mainly supplies crude phosphorus pentasulfide product to the multi-step distillation device, and its discharge port 1 - 1 is connected to the feeding port 2 - 1 of the multi-step distillation device 2 .

The multi-step distillation equipment 2 is a multi-device combined distillation equipment, which is mainly used for distilling and purifying the crude product of phosphorus pentasulfide, and is mainly composed of a heavy salt removal distillation tower (heavy salt removal distillation equipment) 2A, a light impurity removal distillation tower (light impurity removal distillation equipment) 2B and an organic impurity removal distillation tower (organic impurity removal distillation equipment) 2C.

The heavy salt removal distillation tower 2A is a composite distillation tower composed of tower plates and fillers, with fillers in the distillation section and tower plates in the stripping section. Its feed port 2-1 is connected to the discharge port 1-1 of the feed equipment 1, its heavy salt impurity outlet 2-2 at the bottom of the tower is connected to the heavy salt impurity inlet of the distillation component storage device 3, and the light impurity outlet 2-6 at the top of the tower is connected to the feed port 2-7 of the light impurity removal distillation tower (light impurity removal distillation equipment) 2B.

The light impurity removal distillation tower 2B is a packed distillation tower, whose feed port 2-7 is connected to the light impurity outlet 2-6 of the heavy salt removal distillation tower 2A, the phosphorus pentasulfide outlet 2-3 of the tower bottom is connected to the heavy salt impurity inlet 3-2 of the distillation component storage device 3, and the light impurity outlet 2-8 at the top of the tower is connected to the feed port 2-9 of the organic impurity removal distillation tower 2C.

The organic impurity removal distillation tower 2C is a packed distillation tower, whose feed port 2-9 is connected to the light impurity outlet port 2-8 at the top of the organic impurity removal distillation tower 2A, its light sulfur and phosphorus impurity outlet port 2-4 at the bottom of the tower is connected to the light sulfur and phosphorus impurity inlet port 3-3 of the distillation component storage device 3, and the organic impurity outlet port 2-5 at the top of the tower is connected to the organic impurity inlet port 3-4 of the distillation component storage device 3.

The distillation component storage device 3 mainly includes a heavy salt storage device 3A, a high-purity phosphorus pentasulfide storage device 3B, a light phosphorus sulfur impurity storage device 3C, and an organic impurity storage device 3D.

The heavy salt impurity inlet 3-1 of the distillation component storage device 3 is connected to the heavy salt impurity outlet 2-2 of the multi-step distillation device 2, so as to transport the heavy salt impurities to the heavy salt impurity storage device 3A; the phosphorus pentasulfide inlet 3-2 of the distillation component storage device 3 is connected to the phosphorus pentasulfide outlet 2-3 of the multi-step distillation device 2, so as to transport the phosphorus pentasulfide to the phosphorus pentasulfide storage device 3B; the light phosphorus sulfur impurity inlet 3-3 of the distillation component storage device 3 is connected to the light phosphorus sulfur impurity outlet 2-4 of the multi-step distillation device 2, so as to transport the light phosphorus sulfur impurities to the light phosphorus sulfur impurity storage device 3C; the organic impurity inlet 3-4 of the distillation component storage device 3 is connected to the organic impurity inlet 2-5 of the multi-step distillation device 2, so as to transport the organic impurities to the organic impurity inlet 3D.

A feeding device 1 is used to supply a liquid crude phosphorus pentasulfide product a to a multi-step distillation device 2 with a tower top pressure of 101 KPaA. The crude phosphorus pentasulfide product has a temperature of 510°C, a boiling point of 510°C, and a composition of: a pure phosphorus pentasulfide content of 90 wt.%, a boiling point of 515°C (101 KPaA)/385°C (10 KPaA);

The heavy salt impurity content is 3 wt.%, the boiling point is 520 ℃ (101 KPaA)/390 ℃ (10 KPaA)-550 ℃ (101 KPaA)/430 ℃ (10 KPaA);

The light sulfur phosphorus impurity is 5 wt.%, and the boiling point is 286 ℃ (101 KPaA)/190 ℃ (10 KPaA)-510 ℃ (101 KPaA)/380 ℃ (10 KPaA);

The organic impurities are 2 wt.%, and the boiling points are 120 ℃ (101 KPaA)/60 ℃ (10 KPaA)-280 ℃ (101 KPaA)/160 ℃ (10 KPaA).

After the crude phosphorus pentasulfide product a enters the multi-step distillation equipment 2, it first enters the heavy removal distillation tower 2A for heavy removal distillation.

The crude phosphorus pentasulfide product a entering the de-heavy distillation tower 2A conducts heat and mass transfer with the high-temperature gas rising from the stripping section of the de-heavy distillation tower 2A and is heated to about 520°C. The components with lower boiling points (phosphorus pentasulfide c, light sulfur phosphorus impurities d and organic impurities e) in the crude phosphorus pentasulfide product a are vaporized into gas and enter the distillation section, and are gradually cooled by heat and mass exchange with the liquid from the upper part of the distillation section. The components with higher boiling points (mainly heavy salt impurities) carried therein are re-liquefied and returned to the stripping section, thereby separating the components with higher boiling points from the components with lower boiling points. When the gas drops to about 515°C, the gas is discharged from the top of the tower and condensed into light components of the de-heavy distillation tower and discharged from the light component outlet 2-6.

The liquid components that cannot be vaporized gradually enter the tower kettle and are heated to about 525°C. The liquid is vaporized again and enters the distillation section to exchange heat and mass with the low-temperature liquid coming down from the upper part and is cooled. The components with lower boiling points enter the distillation section in gaseous form, while the components with higher boiling points re-enter the tower kettle, thereby realizing the separation of components in the liquid material. The separated heavy salt impurities b with higher boiling points are discharged as heavy components through the heavy salt impurity outlet 2-2 at the bottom of the tower kettle.

The heavy salt impurities b discharged from the heavy salt impurities outlet 2-2 at the bottom of the heavy salt impurities removal distillation tower kettle enter the heavy salt impurities storage device 3A in the distillation component storage device 3 through the heavy salt impurities inlet 3-1 for storage in order to be centrally processed.

The light components c+d+e (mainly phosphorus pentasulfide, light sulfur phosphorus impurities and organic impurities) discharged from the light component outlet 2-6 at the top of the heavy salt impurity removal distillation tower enter the light impurity removal distillation tower 2B through the feed inlet 2-7 for light impurity removal distillation.

The light components c+d+e of the heavy salt impurity removal distillation entering the light impurity removal distillation tower 2B are subjected to light impurity removal distillation. The operating pressure and temperature at the top of the light impurity removal distillation tower 2B are 10 KPaA and 380°C, respectively. The light components c+d+e of the heavy salt impurity removal distillation are separated into light components d+e (mainly light sulfur and phosphorus impurities d and organic impurities e) of light impurity removal distillation and heavy components c (mainly phosphorus pentasulfide c) of light impurity removal distillation, and are discharged from the light component outlet 2-8 at the top of the light impurity removal distillation tower 2B and the phosphorus pentasulfide outlet 2-3 of the tower bottom, respectively.

The heavy component c of the light impurity removal distillation discharged from the phosphorus pentasulfide outlet 2-3 of the light impurity removal distillation tower 2B enters the phosphorus pentasulfide storage device 3B in the distillation component storage device 3 through the phosphorus pentasulfide inlet 3-2 and is used as a high-purity phosphorus pentasulfide product. Among them, the mass of the discharged high-purity phosphorus pentasulfide product is 0.895 t, and the contents of phosphorus pentasulfide, organic impurities, light sulfur phosphorus impurities and heavy salt impurities are 99.7 wt.%, 0.08 wt.%, 0.18 wt.% and 0.02 wt.%, respectively. The recovery rate of phosphorus pentasulfide components reaches 99.15%, of which the phosphorus content is 28.0% and the sulfur content is 71.97%.

The light components d+e discharged from the light component outlet 2-8 of the light impurity removal distillation tower 2B enter the organic impurity removal distillation tower 2C through the feed inlet 2-9 for organic impurity removal distillation.

The light component d+e of the delight impurity distillation entering the delight impurity distillation tower 2C is delighted with organic impurities. The operating pressure and temperature of the tower top of the delight impurity distillation tower 2B are 10 KPaA and 160 °C, respectively. The light component d+e of the delight impurity distillation is separated into the light component e of the delight impurity distillation (mainly organic impurities e) and the heavy component d of the delight impurity distillation (mainly light sulfur and phosphorus impurities d) and discharged from the organic impurity outlet 2-5 located at the top of the delight impurity distillation tower 2C and the light sulfur and phosphorus impurity outlet 2-4 of the tower bottom, respectively. Among them, the mass of the discharged high-purity phosphorus pentasulfide product is 0.0495 t, and the contents of pure light sulfur and phosphorus impurities, organic impurities, pure phosphorus pentasulfide and heavy salt impurities are 94 wt.%, 0.5 wt.%, 5.0 wt.% and 0.5 wt.%, respectively. The recovery rate of light sulfur and phosphorus impurities is 93.06%.

The heavy component d of the organic impurity removal distillation discharged from the light sulfur phosphorus impurity outlet 2-4 of the organic impurity removal distillation tower 2C enters the light sulfur phosphorus impurity equipment 3C in the distillation component storage device 3 through the light sulfur phosphorus impurity inlet 3-3 for storage, and then returns to the phosphorus pentasulfide synthesis system for reuse as sulfur phosphorus raw material.

The light component d of the organic impurity removal distillation discharged from the organic impurity outlet 2-5 of the organic impurity removal distillation tower 2C enters the organic impurity device 3C in the distillation component storage device 3 through the organic impurity inlet 3-4 for storage so as to be processed centrally.

Through this embodiment, the crude phosphorus pentasulfide product can be distilled and separated into phosphorus pentasulfide product, light sulfur phosphorus impurities, heavy salt impurities and organic impurities. Thus, a phosphorus pentasulfide product is obtained, and the contents of phosphorus pentasulfide, organic impurities, light sulfur phosphorus impurities and heavy salt impurities in the phosphorus pentasulfide product are 99.7 wt.%, 0.08 wt.%, 0.18 wt.% and 0.02 wt.%, respectively, the phosphorus content is 28.0%, and the sulfur content is 71.97%, which meets the requirements of the superior high-purity phosphorus pentasulfide product specified in the National Standard of the People's Republic of China "Industrial Phosphorus Pentasulfide" (GB/T13258-2016), and the organic impurity content is low, which is 0.08 wt.%, and meets the quality requirements of phosphorus pentasulfide products in industries such as lubricating oil manufacturing that have high requirements for phosphorus pentasulfide products, and the recovery rate of phosphorus pentasulfide components is 99.15%, and the recovery rate of phosphorus pentasulfide components is high. At the same time, 93.06% of the light sulfur phosphorus impurities can be recovered, and the recovery rate is relatively high. In addition, compared with Example 1, the negative pressure distillation is adopted, and the distillation temperature is greatly reduced, which can effectively reduce the energy consumption in the purification process of phosphorus pentasulfide, and the energy saving effect is remarkable.

Claims (16)

1. A method for preparing a purified high-purity phosphorus pentasulfide, characterized in that: The crude phosphorus pentasulfide product is added to a multi-step distillation device in a certain phase state for multi-step purification; The purification steps in the multi-step distillation device include three purification steps: heavy salt removal distillation, light impurity removal distillation and organic impurity removal distillation; The heavy salt removal distillation is to separate the phosphorus pentasulfide product into heavy components mainly composed of heavy salt impurities and light components with a boiling point of phosphorus pentasulfide or lower at a certain temperature and pressure; The light impurity removal distillation is to separate the crude phosphorus pentasulfide product into heavy components mainly composed of phosphorus pentasulfide and light impurity components with a boiling point lower than that of phosphorus pentasulfide by distillation at a certain temperature and pressure; The organic impurity removal distillation is to separate the light impurity components of the light impurity removal distillation into heavy components mainly composed of light sulfur and phosphorus impurities and light components mainly composed of organic impurities at a certain temperature and pressure and discharge them, thereby achieving the purification of phosphorus pentasulfide. 2. The purification method for preparing high-purity phosphorus pentasulfide according to claim 1, characterized in that the crude phosphorus pentasulfide product is in a gaseous form or a liquid form during the distillation feed. 3. The purification method for preparing high-purity phosphorus pentasulfide according to claim 2 is characterized in that, in the multi-step purification steps carried out in the multi-step distillation device, the order of heavy salt removal distillation, light impurity removal distillation, and organic impurity removal distillation is not fixed and can be arbitrarily adjusted. 4. The purification method for preparing high-purity phosphorus pentasulfide according to claim 3, characterized in that in the multi-step purification steps in the multi-step distillation device, purification is carried out in the order of heavy salt removal distillation, light impurity removal distillation, and organic impurity removal distillation; Alternatively, purification is carried out in the order of distillation for light impurities removal, distillation for organic impurities removal and distillation for heavy salt removal; Alternatively, purification is carried out in the order of distillation to remove organic impurities, distillation to remove light impurities and distillation to remove heavy salts. 5. The purification method for preparing high-purity phosphorus pentasulfide according to claim 4, characterized in that, in the purification process according to the order of heavy salt removal distillation, light impurity removal distillation, and organic impurity removal distillation, the crude product is distilled and separated into heavy components mainly composed of heavy salt impurities with a higher boiling point than phosphorus pentasulfide and light components mainly composed of phosphorus pentasulfide and light sulfur impurities and organic impurities with a lower boiling point than phosphorus pentasulfide at a certain temperature and pressure, and discharged; The discharged light components of the heavy salt removal distillation are subjected to light impurity removal distillation. At a certain temperature and pressure, the light components of the heavy salt removal distillation are separated by distillation into heavy components mainly composed of phosphorus pentasulfide and light impurity components mainly composed of light sulfur phosphorus impurities and organic impurities, and then discharged; The discharged light components of the light impurity removal distillation are subjected to organic impurity removal distillation. Under a certain temperature and pressure, the light components of the light impurity removal distillation are separated by distillation into heavy components mainly composed of light sulfur and phosphorus impurities and light components mainly composed of organic impurities and discharged. 6. The purification method for preparing high-purity phosphorus pentasulfide according to claim 5, characterized in that the content of pure phosphorus pentasulfide in the crude phosphorus pentasulfide product is 85-90 wt.%, the content of heavy salt impurities with a boiling point of 520-550°C is 3-5 wt.%, the content of light sulfur impurities with a boiling point of 286-510°C is 5-8 wt.%, and the content of organic impurities with a boiling point of 120-280°C is 2-4 wt.%. 7. The purification method for preparing high-purity phosphorus pentasulfide according to claim 6, characterized in that the multi-step distillation is atmospheric distillation, or vacuum distillation, or a combination of atmospheric distillation and vacuum distillation. 8. The purification method for preparing high-purity phosphorus pentasulfide according to claim 7, characterized in that: When it is atmospheric distillation, the distillation pressure is zero pressure or slightly positive pressure, and the operating pressure of atmospheric distillation is 100-110 KPaA; In the case of vacuum distillation, the distillation pressure is absolute zero pressure, and the operating pressure of vacuum distillation is 10-20 KPaA. 9. The purification method for preparing high-purity phosphorus pentasulfide according to claim 8, characterized in that: In the atmospheric distillation, vacuum distillation, or the combination of atmospheric distillation and vacuum distillation, the distillation temperature is determined by the boiling point of the distillation property and the operating pressure; the distillation temperature is the boiling point temperature of the distillation light component corresponding to the distillation pressure; In the heavy salt removal distillation stage, the light impurity removal distillation stage and the organic impurity removal distillation stage, the light components are respectively a mixture of phosphorus pentasulfide and materials with a boiling point lower than phosphorus pentasulfide, a mixture of materials with a boiling point lower than phosphorus pentasulfide, and organic impurities. In these three distillation sections, the operating temperatures are the boiling points of the corresponding mixtures. 10. A purification device for preparing high-purity phosphorus pentasulfide, used in the method according to any one of claims 1 to 9, characterized in that: The device comprises a feeding device (1), a multi-step distillation device (2), and a distillation component storage device (3); The feed device (1) is connected to the feed port (2-1) of the multi-step distillation device (2). The feed device is a gaseous feed device or a liquid feed device. Its feed port is connected to the phosphorus pentasulfide synthesis system, and its discharge port is connected to the feed port (2-1) of the multi-step distillation device. The multi-step distillation equipment (2) is a multi-device combined distillation equipment, comprising a heavy salt removal distillation tower (2A), a light impurity removal distillation tower (2B) and an organic impurity removal distillation tower (2C); The heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are integrated into one whole device; Or the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are independently dispersed combined equipment, and the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are atmospheric pressure distillation equipment or vacuum distillation equipment; The distillation component storage device (3) includes a heavy salt storage device (3A), a high-purity phosphorus pentasulfide storage device (3B), a light phosphorus sulfur impurity storage device (3C), and an organic impurity storage device (3D). 11. The purification device for preparing high-purity phosphorus pentasulfide according to claim 10, characterized in that: When the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are integrated whole equipment or independently dispersed combined equipment, the sequence of the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) is not fixed; That is, when the whole device is integrated, the upper part of the whole device is any one of the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C), and the lower part of the whole device is another one or two distillation towers; In the case of independently dispersed combined equipment, from front to back, they are a heavy salt removal distillation tower (2A), a light impurity removal distillation tower (2B) and an organic impurity removal distillation tower (2C); or a light impurity removal distillation tower (2B), an organic impurity removal distillation tower (2C) and a heavy salt removal distillation tower (2A); or an organic impurity removal distillation tower (2C), a light impurity removal distillation tower (2B) and a heavy salt removal distillation tower (2A). 12. The purification device for preparing high-purity phosphorus pentasulfide according to claim 11, characterized in that: When the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are integrated into one whole device, the multi-step distillation equipment (2) is an integrated baffle plate distillation tower, and the lower part of the distillation tower body is divided into two areas by a baffle, the side close to the feed inlet (2-1) is the light impurity removal distillation tower (2B), and the other side is the heavy salt removal distillation tower (2A), and the upper part of the distillation tower is the organic impurity removal distillation tower (2C). 13. The purification device for preparing high-purity phosphorus pentasulfide according to claim 11, characterized in that: The bottom of the tower kettle of the multi-step distillation device (2) is provided with a heavy salt impurity outlet (2-2), which is connected to the heavy salt impurity inlet (3-1) of the heavy salt storage device (3A); The top of the multi-step distillation device (2) is provided with an organic impurity outlet (2-5), which is connected to an organic impurity inlet (3-4) of an organic impurity storage device (3D); A phosphorus pentasulfide outlet (2-3) is provided on the side wall of the heavy salt removal distillation tower (2A) of the multi-step distillation device (2), and the phosphorus pentasulfide outlet (2-3) is connected to a phosphorus pentasulfide inlet (3-2) of a high-purity phosphorus pentasulfide storage device (3B); A light sulfur phosphorus impurity outlet (2-4) is provided on the side wall of the organic impurity removal distillation tower (2C) of the multi-step distillation device (2), and the light sulfur phosphorus impurity outlet (2-4) is connected to a light sulfur phosphorus impurity inlet (3-3) of the light sulfur phosphorus impurity storage device (3C). 14. The purification device for preparing high-purity phosphorus pentasulfide according to claim 13, characterized in that the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are independently dispersed combined equipment, the feed equipment outlet (1-1) of the feed equipment (1) is connected to the feed inlet (2-1) of the heavy salt removal distillation tower (2A), and the heavy salt removal distillation equipment light outlet group (2-6) at the top of the heavy salt removal distillation tower (2A) is connected to the feed inlet (2-7) in the middle of the light impurity removal distillation tower (2B); The light component outlet (2-8) of the light impurity removal distillation equipment at the top of the light impurity removal distillation tower (2B) is connected to the feed inlet (2-9) in the middle of the organic impurity removal distillation tower (2C). 15. The purification device for preparing high-purity phosphorus pentasulfide according to claim 14, characterized in that the heavy salt impurity outlet (2-2) of the heavy salt removal distillation tower (2A) is connected to the heavy salt impurity inlet (3-1) of the heavy salt storage device (3A); The phosphorus pentasulfide outlet (2-3) of the light impurity removal distillation tower (2B) is connected to the phosphorus pentasulfide inlet (3-2) of the high-purity phosphorus pentasulfide storage device (3B); The light sulfur and phosphorus impurity outlet (2-4) of the organic impurity removal distillation tower (2C) is connected to the light sulfur and phosphorus impurity inlet (3-3) of the organic impurity storage device (3D); The organic impurity outlet (2-5) of the organic impurity removal distillation tower (2C) is connected to the organic impurity inlet (3-4) of the organic impurity storage device (3D). 16. The purification device for preparing high-purity phosphorus pentasulfide according to claim 10, characterized in that the heavy salt removal distillation tower (2A), the light impurity removal distillation tower (2B) and the organic impurity removal distillation tower (2C) are packed distillation equipment, or plate distillation equipment, or a combined packing and plate distillation equipment.