Crude arsenic purification method and application

Abstract

The invention provides a crude arsenic purification method and application. The crude arsenic purification method comprises the following steps: placing a crude arsenic raw material in a vacuum environment with the pressure not greater than 1Pa, the hot end temperature of 600-900 DEG C and the cold end temperature of 400-700 DEG C, and carrying out vacuum sublimation by adding a reducing agent and a purifying agent to obtain a sublimation product; and cooling the obtained sublimation product to normal temperature, and crushing under the protection of inert gas to obtain the purified elemental arsenic product, so that the impurity content of the obtained arsenic product is greatly reduced, and the purity is remarkably improved. According to the method, the sublimation temperature of arsenic is reduced under the high vacuum condition, and the difference among the saturated vapor pressure, the volatilization rate and the boiling point of arsenic and impurity metal at the low sublimation temperature is utilized; the low-value metal crude arsenic is converted into a low-impurity-content and high-value simple substance arsenic product, and the method is widely applied to crude arsenic purification.

Description

Technical Field

[0001] The invention relates to the field of arsenic extraction, and in particular to a crude arsenic purification method and application. Background Art

[0002] Smelting processes such as lead and zinc smelting and copper smelting will produce a large amount of arsenic-containing waste slag. Crude arsenic is usually a by-product of non-ferrous metal smelting. Among them, the output of crude arsenic increases with the increase of non-ferrous metal output. Therefore, in areas with large non-ferrous metal output, the output of crude arsenic is particularly significant. As a toxic heavy metal element, arsenic will cause serious damage to soil, water sources and ecosystems if it is discharged directly into the environment without treatment.

[0003] Elemental arsenic is an important semiconductor material with a wide range of applications in electronic and optoelectronic devices; however, arsenic is highly chemically active and is easily contaminated by impurities during the preparation process, especially the doping of elements such as antimony, which not only affects the performance of arsenic, but also severely restricts its application in the field of high-end technology. Currently, traditional methods for purifying crude arsenic, such as pyrolysis, can effectively remove certain low-melting-point impurities, but have limited effects on certain high-melting-point metal impurities, and the energy consumption caused by high-temperature operation makes its cost relatively high. In addition, the overall processing efficiency of wet extraction is low, and the solubility differences of most components are small, making it difficult to purify crude arsenic in depth.

[0004] In view of the technical challenges of crude arsenic processing and purification, as well as the dual demands of environmental protection and industrial application, the present invention aims to propose a crude arsenic purification method and application to solve or at least alleviate the technical problems of difficulty in deep processing and purification of crude arsenic materials and difficulty in removing impurity elements. Summary of the invention

[0005] The main purpose of the present invention is to provide a crude arsenic purification method and application, so as to solve the technical problems that the crude arsenic material is difficult to be deeply processed and purified, and the impurity elements are difficult to remove, especially the elements of the same group are difficult to remove; the crude arsenic is innovatively purified by adding a purifying agent and a reducing agent in a vacuum environment, so as to improve the purity and quality of elemental arsenic and meet the demand of modern industry for high-purity arsenic products.

[0006] To achieve the above object, the present invention provides a method for purifying crude arsenic, comprising: The crude arsenic, the reducing agent and the purifying agent are mixed to obtain a mixed arsenic material; The mixed arsenic material is placed in a sealed high vacuum environment, which includes a hot end and a cold end. The mixed arsenic material sublimates at the hot end and condenses at the cold end. The condensate at the cold end is collected to obtain arsenic element. The vacuum pressure in the high vacuum environment is not greater than 1Pa. The temperature of the hot end is 600~900℃, and the temperature difference between the hot end and the cold end is not less than 200℃; the temperature of the cold end is 400~700℃.

[0007] Furthermore, the vacuum pressure in the high vacuum environment is 0.001~0.1Pa.

[0008] Furthermore, the reducing agent includes one or more of zinc powder, iron powder, magnesium powder, and carbon powder.

[0009] Furthermore, the purifying agent includes one or more of copper powder, cadmium powder, lead powder, and sulfuric acid.

[0010] Furthermore, the purity of the crude arsenic is 1N to 3N; the impurity elements in the crude arsenic include antimony and sulfur; and the oxygen content of the crude arsenic is >5%.

[0011] Furthermore, the amount of reducing agent added is 1-5% of the mass of crude arsenic.

[0012] Furthermore, the amount of the purifying agent added is 2-10% of the mass of the crude arsenic.

[0013] Furthermore, in the process of sublimating the mixed arsenic material at the hot end and condensing at the cold end, and collecting the condensate at the cold end to obtain the arsenic element, the sublimation time at the hot end is not less than 2 hours.

[0014] Furthermore, the process of sublimating the mixed arsenic material at the hot end and condensing at the cold end, and collecting the condensate at the cold end to obtain the arsenic element also includes transferring the arsenic element to an inert atmosphere, and performing crushing and screening in sequence; wherein the crushing time is 5 to 30 minutes, and the particle size of the screening treatment is 200 to 400 meshes.

[0015] The present invention provides an application of any one of the above crude arsenic purification methods in the production of elemental arsenic and arsenide.

[0016] The beneficial effects of the present invention are as follows: The present invention controls the vacuum pressure in the vacuum environment to be no more than 1Pa, reduces the sublimation temperature of arsenic, utilizes the difference between the saturated vapor pressure, volatilization rate and boiling point of arsenic and the main impurity antimony at low sublimation temperature to separate the two, effectively alleviates the problem of difficult impurity separation in the sublimation process of crude arsenic, and obtains high-purity elemental arsenic. In addition, by adding a reducing agent and a purifying agent, the oxide of arsenic is reduced to elemental arsenic, and a reducing environment is maintained at high temperature to prevent the reoxidation of arsenic, thereby avoiding the arsenic oxide from escaping to the cold end due to the larger saturated vapor pressure and diffusion. This process not only improves the volatilization efficiency of arsenic, but also enhances its ability to dissociate from the oxide. On the other hand, purifying agents such as copper powder and cadmium powder effectively separate these impurities from arsenic by forming non-volatile compounds with sulfur. These compounds remain in the solid residue during the sublimation process, preventing the volatilization of impurities. The use of the purifying agent also enhances the chemical stability of the system, avoids the occurrence of side reactions, and ensures the specificity and efficiency of the purification process. During the sublimation process, arsenic changes directly from solid to gas, and its particles or molecules have greater activity and a wider distribution range in the gaseous state. In addition, the temperature at the hot end is sufficient to provide the required activation energy for the oxidation process of arsenic. At this time, high vacuum condition control is necessary. High vacuum technology significantly reduces the introduction of impurities, reduces the risk of oxidation, and improves the chemical purity and crystal quality of elemental arsenic.

[0017] The present invention mixes crude arsenic with a reducing agent, which, on the one hand, avoids the negative effects of oxidized impurities (such as high-valent arsenic oxides) on the sublimation efficiency of arsenic and the purity of the product. The addition of an appropriate amount of reducing agent can reduce these oxidized impurities to low-valent arsenic that is easier to sublimate, and at the same time, the addition of a purifying agent fixes the impurities and purifies the arsenic, thereby making the purification of arsenic relatively thorough. On the other hand, the reducing agent can create a reducing atmosphere to ensure that the arsenic is not oxidized during the sublimation process.

[0018] The present invention achieves high-efficiency purification of arsenic resources by purifying arsenic from crude arsenic or other arsenic-containing byproducts. This method not only increases the value of arsenic resources, but also reduces the environmental risks caused by arsenic waste, and has both economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0020] Figure 1 Schematic diagram of the process of crude arsenic purification in an embodiment of the present invention; Figure 2 1 is an elemental analysis diagram of the crude arsenic raw material in Examples 1 to 9 of the present invention and Comparative Examples 1 to 5; Figure 3 1 is a purity analysis chart of crude arsenic raw materials in Examples 1 to 9 of the present invention and Comparative Examples 1 to 5; Figure 4 is the XRD diagram of the crude arsenic raw material in Examples 1 to 9 of the present invention and Comparative Examples 1 to 5; Figure 5 This is a purity analysis chart of all elements of pure arsenic obtained in Example 4 of the present invention.

[0021] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in 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 creative work are within the scope of protection of the present invention.

[0023] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0024] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] like Figure 1 As shown, the present invention provides a method for purifying crude arsenic, comprising the following steps: S1, crude arsenic, reducing agent and purifying agent are mixed to obtain mixed arsenic material.

[0026] Crude arsenic is an arsenic product prepared from arsenic oxide through a carbon reduction process. It has a high impurity content and low economic value. It is usually a by-product of non-ferrous metal smelting, such as lead and zinc smelting, copper smelting, etc. These smelting processes produce a large amount of arsenic-containing waste slag. The output of crude arsenic increases with the increase in non-ferrous metal output. Therefore, in areas with large non-ferrous metal output, the output of crude arsenic is particularly high.

[0027] The utilization of crude arsenic has important environmental significance. Arsenic is a toxic heavy metal element. If it is discharged directly into the environment without treatment, it will cause serious damage to the soil, water sources and ecosystems. Secondly, the reuse of crude arsenic helps to reduce the exploitation of natural resources, promotes the recycling of resources, and is in line with the concept of sustainable development. In addition, by converting crude arsenic into valuable purified arsenic products, it can bring economic benefits to related companies and also promote the development and application of environmental protection technologies.

[0028] The main impurity of crude arsenic is antimony. Since arsenic and antimony belong to the VA group elements and have similar chemical properties, they are difficult to separate under normal conditions. However, by controlling the reaction temperature under high vacuum conditions and taking advantage of the significant difference in saturated vapor pressure and maximum volatilization rate between arsenic and antimony under high vacuum and low temperature conditions, the residual amount of antimony can be effectively reduced. At this temperature, the volatilization rate of arsenic is significantly higher than that of antimony, so that arsenic can be sublimated to the cold end first, which improves the purity of the product and reflects the innovation of the present invention.

[0029] The calculation formula for the saturated vapor pressure of each metal is: According to the above formula, the saturated vapor pressure of each metal is calculated as: The present invention controls the vacuum pressure in the vacuum environment to be no more than 1Pa, and utilizes the differences in saturated vapor pressure, volatilization rate and boiling point between arsenic and the main impurity antimony to separate the two, effectively alleviating the problem of difficulty in separating impurities during the sublimation of crude arsenic, thereby obtaining high-purity elemental arsenic.

[0030] The high vacuum environment provides a preparation condition with almost no interference from gas molecules, which helps to reduce the introduction of impurities and improve the purification efficiency. Under high vacuum conditions, elemental arsenic can be purified through the sublimation process, in which solid substances are directly converted into gas without passing through the liquid state; in a high vacuum environment, the sublimation process can be carried out more efficiently because the interference of gas molecules on the sublimation process is reduced.

[0031] During the purification process, elemental arsenic is heated to the sublimation point, and the arsenic molecules will detach from the solid surface and enter the vacuum environment. Due to the different sublimation temperatures of arsenic and antimony, the separation of arsenic and antimony can be achieved by precisely controlling the temperature of the hot end. In addition, a high vacuum environment also helps to reduce the oxidation and hydrolysis of arsenic during the sublimation process, thereby ensuring the chemical purity of the purified elemental arsenic. High vacuum sublimation purification technology combined with precise temperature control and atmosphere management provides a new way to prepare high-purity elemental arsenic, which can not only improve the purity of elemental arsenic, but also reduce by-products and operational risks in the preparation process, which is of great significance for promoting the development of semiconductor material technology.

[0032] In some embodiments of the present invention, the particle size of the crude arsenic can be 0.5~3cm, and the purity of the crude arsenic can be 1N~3N. For example, the purity of the crude arsenic can be 1N~2N; for another example, the purity of the crude arsenic can be 2N; it should be noted that, taking 2N grade crude arsenic as an example, 2N grade crude arsenic is an arsenic element with an impurity content ≤1% and >0.1%.

[0033] Quantitative element analysis of crude arsenic shows that the Sb content in crude arsenic can reach 1~1500ppm, for example, the antimony content in crude arsenic can be 500~1500ppm; for example, the antimony content in crude arsenic can be 1000~1500ppm, antimony is the impurity element with the highest content in crude arsenic, and other impurity elements include Si, S, and B, with contents of 40~60ppm, 4~5ppm, and 1~2ppm respectively; impurities in crude arsenic can specifically include Sb and S, and the contents are described above; the oxygen content of crude arsenic is >5% or ≤5%; further, the oxygen content in crude arsenic can be 5~10%. It should be noted that the oxygen content of crude arsenic here refers to the mass fraction of oxygen in crude arsenic.

[0034] In some embodiments, the reducing agent may not include aluminum powder; exemplary, the reducing agent may include one or more of zinc powder, iron powder, magnesium powder, and carbon powder. Exemplary, the reducing agent may include one or more of zinc powder, iron powder, and carbon powder.

[0035] In some embodiments, the particle size of the reducing agent may be 200 mesh.

[0036] The present invention mixes crude arsenic with a reducing agent, which, on the one hand, avoids the negative impact of oxidized impurities (such as high-valent arsenic oxides) on the sublimation efficiency of arsenic and the purity of the product. The addition of an appropriate amount of reducing agent can reduce these oxidized impurities to low-valent arsenic that is easier to sublimate, thereby making the purification of arsenic relatively thorough. On the other hand, the reducing agent can create a reducing atmosphere to ensure that the arsenic is not oxidized during the sublimation process.

[0037] In some embodiments, the amount of reducing agent added may be 1-5% of the mass of crude arsenic.

[0038] In some specific embodiments, crude arsenic, a purifying agent and a reducing agent can be placed in an inert atmosphere in proportion and fully ground and mixed in a mixer to obtain a mixed arsenic material. The mixed arsenic material is then placed in a vacuum container, which is sealed and evacuated to 0.001-0.1 Pa and then placed in a furnace structure having a hot end and a cold end.

[0039] In the present invention, the purifying agent may include one or more of copper powder, cadmium powder, lead powder, and sulfuric acid.

[0040] In some embodiments of the present invention, when the purifying agent is sulfuric acid, the concentration of the sulfuric acid may be 90-95%.

[0041] In some embodiments of the present invention, the purifying agent may include copper powder and / or sulfuric acid.

[0042] In the present invention, the amount of the purifying agent added can be 2-10% of the mass of the crude arsenic.

[0043] In some preferred embodiments, the reducing agent may be one of carbon powder, zinc powder, and iron powder, and the purifying agent may be one of copper powder and sulfuric acid; In some preferred embodiments, the reducing agent may be one of carbon powder and iron powder, and the purifying agent may be copper powder; In some preferred embodiments, the reducing agent is carbon powder and the purifying agent is copper powder; In some preferred embodiments, the reducing agent is carbon powder and the purifying agent is sulfuric acid.

[0044] S2, placing the mixed arsenic material in a sealed high vacuum environment, the high vacuum environment includes a hot end and a cold end, the mixed arsenic material sublimates at the hot end and condenses at the cold end, and the condensate at the cold end is collected to obtain arsenic element.

[0045] In some embodiments, the vacuum pressure in the high vacuum environment is no greater than 1 Pa.

[0046] In some embodiments, the vacuum pressure in the high vacuum environment may be 0.001-0.1 Pa. It should be noted that the vacuum pressure here is equivalent to the vacuum degree, that is, it expresses the specific apparent pressure value of the gas in the vacuum environment.

[0047] In some embodiments, the temperature of the hot end is 600-900°C, and the temperature difference between the hot end and the cold end is not less than 200°C; the temperature of the cold end is 400-700°C.

[0048] Among them, when the cold end temperature is lower than 300°C, the adsorption energy will be too low, and it will be difficult for arsenic gas molecules to adhere to the cold end medium.

[0049] In some specific embodiments, the temperature of the hot end may be 600-800° C., and the temperature of the cold end may be 400-600° C. In some more specific embodiments, the temperature of the hot end may be 600-700° C., and the temperature of the cold end may be 400-500° C.

[0050] For example, when the vacuum degree is 0.001 Pa, the hot end temperature can be set to 650° C. and the cold end temperature can be set to 450° C.

[0051] In the present invention, the duration of hot-end sublimation is not less than 2 hours; further, the duration of hot-end sublimation can be 2 to 8 hours; illustratively, the duration of hot-end sublimation can be 6 to 8 hours.

[0052] The mixed arsenic material is sublimated at the hot end and condensed at the cold end, and the step of collecting the arsenic element also includes transferring the arsenic element to an inert atmosphere and crushing the arsenic element in turn; wherein the crushing time is 5 to 30 minutes, and the particle size of the screening treatment is 200 to 400 meshes.

[0053] The inert atmosphere can be nitrogen or argon. The crushing process is to crush the material with a crushing mill and sieve to obtain purified arsenic powder.

[0054] The crushing process can be to use a crushing mill to crush the material and screen it to obtain purified arsenic powder. The crushing time is 5 to 30 minutes, and the sieved particle size can be 200 to 400 meshes.

[0055] The preparation method of the present invention has high impurity removal efficiency and deoxidation performance. By accurately controlling the ratio of additives and reaction conditions, high-purity elemental arsenic can be prepared on a large scale to meet the market demand for high-quality arsenic products. At the same time, the standardized process of this method is also easy to implement in industrial production, ensuring the consistency and reliability of product quality.

[0056] The present invention also provides an application of any one of the above crude arsenic purification methods in the production of elemental arsenic.

[0057] For further understanding of the present invention, examples are given below: It should be noted that the crude arsenic in Examples 1 to 9 and Comparative Examples 1 to 5 all come from crude arsenic products produced by an enterprise in Henan Province through arsenic oxide reduction.

[0058] Example 1 This example adopts the following experimental steps: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0059] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0060] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0061] In this embodiment, the purity of the purified arsenic powder is 99.95%, the antimony content is 286.5 mg / kg, and the oxygen content is 0.31%.

[0062] Example 2 Compared with Example 1, only the dosage of the reducing agent in step 1 is changed: 1. First, place 100 g of crude arsenic, 3 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and add the mixed arsenic material into a vacuum container.

[0063] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0064] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0065] In this embodiment, the purity of the purified arsenic powder is 99.95%, the antimony content is 265.2 mg / kg, and the oxygen content is 0.38%.

[0066] Example 3 Compared with Example 1, only the dosage of the reducing agent in step 1 is changed: 1. First, place 100g of crude arsenic, 1g of carbon powder and 10g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and add the mixed arsenic material into a vacuum container.

[0067] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0068] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0069] In this embodiment, the purity of the purified arsenic powder is 99.95%, the antimony content is 234.3 mg / kg, and the oxygen content is 0.47%.

[0070] Example 4 Compared with Example 1, only the temperature of the hot and cold ends in step 2 is changed: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0071] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 650°C, the cold end temperature is 450°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0072] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0073] In this embodiment, the purity of the purified arsenic powder is 99.99%, the antimony content is 180.7 mg / kg, and the oxygen content is 0.36%.

[0074] Example 5 Compared with Example 1, only the vacuum degree in step 2 is changed: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0075] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.01Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it down to obtain a purified arsenic block.

[0076] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0077] In this embodiment, the purity of the purified arsenic powder is 99.95%, the antimony content is 253.2 mg / kg, and the oxygen content is 0.33%.

[0078] Example 6 Compared with Example 1, only the vacuum degree in step 2 is changed: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0079] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.1Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0080] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0081] In this embodiment, the purity of the purified arsenic powder is 99.95%, the antimony content is 223.5 mg / kg, and the oxygen content is 0.39%.

[0082] Example 7 Compared with Example 1, only the type of reducing agent in step 1 is changed: 1. First, place 100g of crude arsenic, 5g of iron powder and 10g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0083] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0084] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0085] In this embodiment, the purity of the purified arsenic powder is 99.95%, the antimony content is 316.5 mg / kg, and the oxygen content is 0.71%.

[0086] Example 8 Compared with Example 1, only the type of purifying agent in step 1 is changed: 1. First, place 100g of crude arsenic, 5g of carbon powder and 10g of sulfuric acid with a mass concentration of 98% in an inert atmosphere, fully mix them through a mixer to obtain a mixed arsenic material, and add the mixed arsenic material into a vacuum container.

[0087] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0088] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0089] In this embodiment, the purity of the purified arsenic powder is 99.9%, the antimony content is 389.7 mg / kg, and the oxygen content is 0.64%.

[0090] Example 9 Compared with Example 1, only the type of reducing agent in step 1 is changed: 1. First, place 100 g of crude arsenic, 5 g of zinc powder, and 10 g of copper powder in an inert atmosphere, fully mix them with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0091] 2. Evacuate the vacuum container containing the mixed material, seal it after the vacuum degree is drawn to 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0092] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0093] In this embodiment, the purity of the purified arsenic powder is 99.9%, the antimony content is 564.5 mg / kg, and the oxygen content is 0.87%.

[0094] Comparative Example 1 Compared with Example 1, only the type of reducing agent in step 1 is changed: 1. First, place 100g of crude arsenic, 5g of aluminum powder and 10g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0095] 2. Evacuate the vacuum container containing the mixed material, seal it after the vacuum degree is drawn to 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0096] 3. Take out the purified arsenic block under an inert atmosphere, crush it with a grinding machine and then sieve it. Set the crusher time to 10 minutes and the sieve mesh to 200 meshes to finally obtain a purified arsenic powder product that meets the requirements.

[0097] In this comparative example, the purity of the purified arsenic powder is 99.6%, the antimony content is 873.8 mg / kg, and the oxygen content is 1.21%. Due to the poor reduction performance of the reducing agent, arsenic oxide and antimony oxide with high saturated vapor pressure are continuously generated and dissipated to the cold end, resulting in a significant increase in the antimony content concentration in the purified arsenic powder.

[0098] Comparative Example 2 Compared with Example 1, only the temperature of the hot and cold ends in step 2 is changed: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0099] 2. The vacuum container with the mixed material was evacuated to a vacuum degree of 0.001Pa and then sealed. The sealed vacuum container was placed in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature was 450°C, the cold end temperature was 250°C, and the sublimation time was 6 hours. As the volatilization temperature was too low, the arsenic was not completely volatilized.

[0100] Comparative Example 3 Compared with Example 1, only the vacuum degree in step 2 is changed: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0101] 2. The vacuum container with the mixed material was evacuated to 100Pa and then sealed. The sealed vacuum container was placed in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature was 700°C, the cold end temperature was 500°C, and the sublimation time was 6h. Due to the high vacuum pressure, the arsenic was not completely volatilized.

[0102] Comparative Example 4 Compared with Example 1, only the vacuum degree in step 2 is changed: 1. First, place 100 g of crude arsenic, 5 g of carbon powder and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0103] 2. Under normal pressure, the sealed container was placed in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature was 700°C, the cold end temperature was 500°C, and the sublimation time was 6 hours. Due to the lack of vacuum environment, arsenic was not completely volatilized.

[0104] Comparative Example 5 Compared with Example 1, only the purifying agent is added without the reducing agent: 1. First, place 100 g of crude arsenic and 10 g of copper powder in an inert atmosphere, mix them thoroughly with a mixer to obtain a mixed arsenic material, and then add the mixed arsenic material into a vacuum container.

[0105] 2. Evacuate the vacuum container, seal it after the vacuum degree is 0.001Pa, and place the sealed vacuum container in a vacuum sublimation furnace with multiple temperature zones for sublimation reaction. The hot end temperature is 700°C, the cold end temperature is 500°C, and the sublimation time is 6h. After the sublimation reaction is completed, cool it to obtain a purified arsenic block.

[0106] In this comparative example, the purity of the purified arsenic powder is 99.3%, the antimony content is 853.52 mg / kg, and the oxygen content is 4.56%; since no reducing agent is added, the oxidized impurities are difficult to be reduced to low-valent arsenic that is easier to sublime, so the arsenic purification effect is poor, and most of the oxidized arsenic remaining in the crude arsenic is not reduced.

[0107] Analysis example 1 Characterization analysis of crude arsenic used in Examples 1 to 9 and Comparative Examples 1 to 5: 1. Carry out elemental quantitative analysis on crude arsenic. The analysis results are as follows: Figure 2 As shown. Figure 2 It can be observed that the Sb content is as high as 1326.2ppm, which is the impurity element with the highest content. Other impurity elements include Si, S, B, etc. The contents of Si, S, and B are 52.3ppm, 4.6ppm, and 1.5ppm respectively. In addition, the oxygen content is as high as 7.4%. It should be noted that the purity of crude arsenic is 99.1%, which belongs to 2N grade crude arsenic.

[0108] 2. If Figure 3 As shown, the crude arsenic was fully scanned for element content, and the purity was analyzed by the difference method. The analysis results basically corresponded to the results of element quantitative analysis. Sb was the most important impurity in the crude arsenic, with an impurity content of up to 0.18%. Other important impurities included Ca, Fe, K, Na, Se, etc., and the contents of Ca, Fe, K, Na, and Se were 0.0019%, 0.0053%, 0.0010%, 0.0038%, and 0.0037%, respectively.

[0109] 3. Perform XRD phase analysis on crude arsenic. The analysis results are as follows: Figure 4 As shown. Figure 4 It can be observed that the mineral composition of crude arsenic mainly contains elemental arsenic as well as a large amount of arsenic oxide.

[0110] Analysis example 2 Analysis of the purified elemental arsenic and antimony content and optimized purity in Examples 1 to 9 and Comparative Examples 1 to 5: 1. According to the distribution results of the antimony element content of the purified elemental arsenic prepared in Examples 1 to 9 and Comparative Examples 1 to 5, the amount of carbon additive has no obvious effect on the removal of antimony impurities. Compared with the condition of 700°C, the removal of antimony impurities is better under the condition of a lower hot end temperature of 650°C due to the difference in the saturated vapor pressure and the maximum volatilization rate between arsenic and antimony under vacuum conditions. A lower vacuum degree is more conducive to reducing the sublimation temperature, thereby achieving differentiated separation between arsenic and antimony.

[0111] 2. Comprehensive optimal embodiment, under the conditions of hot end temperature 650℃, cold end temperature 450℃, sublimation time 6h, adding 5% carbon powder and 10% copper powder, and vacuum degree 0.001Pa, it can obtain better impurity removal performance, such as Figure 5 As shown, the purity of the pure arsenic prepared in Example 4 was determined by full element determination, and it was found that the antimony content was greatly reduced by more than 89% after vacuum sublimation, and the purity of the crude arsenic after volatilization was increased from 2N to 4N, achieving a good purification effect.

[0112] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for purifying crude arsenic, characterized in that: include: The crude arsenic, the reducing agent and the purifying agent are mixed to obtain a mixed arsenic material; The mixed arsenic material is placed in a sealed high vacuum environment, wherein the high vacuum environment includes a hot end and a cold end, the mixed arsenic material is sublimated at the hot end and condensed at the cold end, and the condensate at the cold end is collected to obtain arsenic element, wherein the vacuum pressure in the high vacuum environment is not greater than 1 Pa; The temperature of the hot end is 600-900°C, and the temperature difference between the hot end and the cold end is not less than 200°C; the temperature of the cold end is 400-700°C.

2. The method for purifying crude arsenic according to claim 1, characterized in that: The vacuum pressure in the high vacuum environment is 0.001~0.1Pa.

3. The method for purifying crude arsenic according to claim 1, characterized in that: The reducing agent includes one or more of zinc powder, iron powder, magnesium powder and carbon powder.

4. The method for purifying crude arsenic according to claim 1, characterized in that: The purifying agent includes one or more of copper powder, cadmium powder, lead powder and sulfuric acid.

5. The method for purifying crude arsenic according to claim 1, characterized in that: The purity of the crude arsenic is 1N to 3N; the impurity elements in the crude arsenic include antimony and sulfur; and the oxygen content of the crude arsenic is >5%.

6. The method for purifying crude arsenic according to claim 1, characterized in that: The amount of the reducing agent added is 1-5% of the mass of the crude arsenic.

7. The method for purifying crude arsenic according to claim 1, characterized in that: The amount of the purifying agent added is 2-10% of the mass of the crude arsenic.

8. The method for purifying crude arsenic according to claim 1, characterized in that: The mixed arsenic material is sublimated at the hot end and condensed at the cold end, and the condensate at the cold end is collected to obtain arsenic element. The sublimation time at the hot end is not less than 2 hours.

9. The method for purifying crude arsenic according to claim 1, characterized in that: The mixed arsenic material is sublimated at the hot end and condensed at the cold end, and the process of collecting the condensate at the cold end to obtain arsenic element also includes transferring the arsenic element to an inert atmosphere, and performing crushing and screening in sequence; wherein the crushing time is 5 to 30 minutes, and the particle size of the screening treatment is 200 to 400 meshes.

10. Use of the crude arsenic purification method according to any one of claims 1 to 9 in the production of elemental arsenic and arsenide.

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