阅读说明：本技术 一种单质砷的制备方法 (Preparation method of simple substance arsenic ) 是由 丘克强 丁杰 于 2019-04-19 设计创作，主要内容包括：本发明属于有害固废处理技术领域,具体公开了一种单质砷的制备方法,其特征在于,将硫化砷原料、金属碳化物的混合物在保护气氛下反应,随后将反应产物进行负压蒸馏,得到单质砷。本发明通过硫化砷原料、金属碳化物在所述的温度条件下进行反应,配合后续的负压蒸馏,可以出人意料地获得晶态单质砷,不仅如此,还能够显著提升单质砷的收率和纯度。(The invention belongs to the technical field of harmful solid waste treatment, and particularly discloses a preparation method of elemental arsenic. According to the invention, the arsenic sulfide raw material and the metal carbide react under the temperature condition, and the subsequent negative pressure distillation is matched, so that the crystalline elemental arsenic can be unexpectedly obtained, and the yield and the purity of the elemental arsenic can be remarkably improved.)

1. A preparation method of simple substance arsenic is characterized in that a mixture of arsenic sulfide raw materials and metal carbide is reacted for not less than 30min in a protective atmosphere at the temperature of not less than 550 ℃, and then a reaction product is subjected to negative pressure distillation to obtain the simple substance arsenic.

2. The method of claim 1, wherein the metal carbide is at least one of calcium carbide, magnesium carbide, sodium carbide, chromium carbide and aluminum carbide; preferably calcium carbide.

3. The method for preparing elemental arsenic according to claim 1 or 2, wherein the metal carbide is not less than the theoretical molar amount of fully reacting the arsenic sulfide raw material, preferably 1 to 2: 1.

4. the method of claim 1, wherein the arsenic sulfide raw material is arsenic sulfide slag.

5. The method for preparing elemental arsenic according to claim 4, wherein the arsenic sulfide slag is subjected to negative pressure distillation purification treatment before mixing;

preferably, the temperature of the negative pressure distillation purification treatment process is 400-600 ℃, and the pressure is 10-100 Pa.

6. The method of preparing elemental arsenic according to claim 1, wherein the reaction temperature is not less than 575 ℃; preferably 575-.

7. The method of claim 1, wherein the reaction time is 30-90 min.

8. The method of claim 1, wherein the pressure of the negative pressure distillation process is 15-25 Pa; the temperature is 450-600 ℃.

9. The method of claim 8, wherein the negative pressure distillation time is not less than 60 min; preferably 60-90 min.

10. A method for recovering elemental arsenic from arsenic sulfide slag, which is characterized in that the arsenic sulfide slag is used as an arsenic sulfide raw material, and the arsenic sulfide slag is treated and the elemental arsenic is co-produced by adopting the preparation method of any one of claims 1 to 9.

Technical Field

The invention relates to the field of resource treatment of arsenide, in particular to a method for recovering simple substance arsenic from arsenic sulfide slag by utilizing the reaction of arsenic sulfide and calcium carbide.

Background

Arsenic is a very harmful metalloid element widely present in nature, and hundreds of currently known arsenic-containing minerals are present. Arsenic compounds are almost all toxic, the toxicity depends mainly on their chemical forms, the toxicity of arsenic in different forms is very different, and the toxicity of inorganic arsenic is higher than that of organic arsenic. Arsenic has special applications in the fields of agriculture, electronics, medicine, metallurgy, chemical industry and the like. The nanometer silicon dioxide/nanometer silicon. The second generation semiconductor material gallium arsenide prepared by taking high-purity arsenic as a raw material has a plurality of better performances compared with the traditional silicon semiconductor material, and the demand of the gallium arsenide semiconductor material is increasing with the coming of the 5G era and the Internet of things. In the smelting process of arsenic-containing ores, a large amount of arsenic enters waste acid wastewater, and the waste acid wastewater treated by a smelting plant mostly adopts a vulcanization process to ensure that the arsenic finally enters arsenic sulfide slag. Because the arsenic sulfide slag is difficult to treat and dispose, a plurality of smelting plants adopt direct stacking, stabilized landfill and other manners to dispose. Such disposal methods not only cause serious harm to the soil environment and human health, but also fail to meet the requirements of full utilization of resources and sustainable development of national economy.

As the arsenic content in the arsenic sulfide slag is very high, the resource utilization of arsenic in the arsenic sulfide slag has very wide prospect. At present, aiming at the resource utilization of arsenic sulfide slag, the main treatment processes include a fire method and a wet method. In the pyrogenic process, arsenic sulfide slag is oxidized and roasted, wherein the arsenic sulfide is converted into arsenic trioxide to be directly volatilized into flue gas, and then the arsenic trioxide is recovered by condensation. The method has the defects of poor product quality, high arsenic content of associated sulfur dioxide flue gas, difficult treatment and serious secondary pollution. The wet process mainly adopts acid leaching, alkali leaching or salt leaching for treatment, arsenic is firstly separated from slag, then arsenic products are further recycled or harmless treatment is carried out, and the products mainly comprise arsenic trioxide, arsenate and the like. The wet treatment has the advantages of no dust generation, low energy consumption and less pollution, but the wet treatment generally has complex production flow and higher treatment cost. The product is arsenic compound arsenic trioxide or arsenate with high toxicity no matter the pyrogenic process or the wet process, and the market demand is limited.

Patent CN106756113A discloses a method for directly producing metallic arsenic by reducing, sulfur-fixing and roasting arsenic sulfide slag, wherein arsenic sulfide slag is used as a raw material, copper oxide and a reducing agent are added, the mixture is reduced, sulfur-fixing and roasting are carried out at a high temperature, and a roasted product is subjected to vacuum separation to obtain elemental arsenic. The copper oxide used by the method is expensive, the copper oxide consumed by obtaining the unit mass of the elemental arsenic product is large in mass, the treatment cost is high, the purity of the obtained elemental arsenic is low, and the recovery rate is low. In addition, the raw material used in the method is the unrefined arsenic sulfide slag which contains a large amount of other metal sulfides, so that the contact between copper oxide and arsenic sulfide is poor, the target reaction efficiency is low, the energy consumption is increased, and the use efficiency of equipment is reduced.

Patent CN103922294A discloses a method for recovering arsenic from arsenic sulfide slag, wherein arsenic sulfide slag is used as a raw material, the arsenic sulfide slag is firstly treated by a segmented vacuum distillation method to obtain pure arsenic sulfide, then iron powder and arsenic sulfide are mixed to react at a high temperature, and the reaction product is subjected to vacuum separation to obtain simple substance arsenic. The method has simple process, and the arsenic sulfide slag can better contact and react with iron powder after being purified. However, the cost of the iron powder required by the method is high, the generated simple substance arsenic and iron generate side reaction to generate an arsenic-iron compound, the utilization rate of the iron powder is reduced, and the recovery rate of the arsenic is also reduced.

The method disclosed in CN 101386915 a utilizes arsenic acid to react with hydrochloric acid and tin dichloride to produce metallic arsenic, and although the reaction in the method is simple, the price of tin dichloride required by the reaction is relatively high, and the purity of the obtained metallic arsenic is not high.

Disclosure of Invention

In order to solve the problems of the prior art, the invention provides a method for preparing simple substance arsenic by arsenic sulfide, and aims to provide a method for preparing simple substance arsenic with high purity, high yield and low cost.

The second purpose of the invention is to provide a method for recovering simple substance arsenic from arsenic sulfide slag, so as to realize resource high-value recovery of arsenic sulfide slag.

A method for preparing simple substance arsenic comprises the steps of reacting a mixture of an arsenic sulfide raw material and a metal carbide in a protective atmosphere at a temperature of not lower than 550 ℃ for not less than 30min, and then carrying out negative pressure distillation on a reaction product to obtain the simple substance arsenic.

The research of the invention unexpectedly finds that the raw material of arsenic sulfide and metal carbide react under the temperature condition and are matched with the subsequent negative pressure distillation, the crystalline simple substance arsenic can be unexpectedly obtained, and the yield and the purity of the simple substance arsenic can be obviously improved.

The invention innovatively provides a concept of preparing simple substance arsenic by reacting arsenic sulfide with metal carbide.

The metal carbide of the present invention includes, but is not limited to, calcium carbide, and may also be metal carbides such as magnesium carbide, sodium carbide, chromium carbide, aluminum carbide, etc.

Preferably, the metal carbide is calcium carbide. Researches show that the calcium carbide has low cost, and can obtain simple substance arsenic with good crystalline state, high yield and high purity.

Preferably, the calcium carbide is not less than the theoretical molar weight of completely reacting the arsenic sulfide raw material, and preferably 1-2: 1.

the arsenic sulfide raw material can be any material containing arsenic sulfide, such as pure arsenic sulfide, or waste residue containing arsenic sulfide, mineral, and the like.

Preferably, the arsenic sulfide raw material is arsenic sulfide slag. According to the method, the arsenic sulfide slag can be recycled, high-quality elemental arsenic is co-produced, and high-value utilization of waste is realized.

Preferably, the arsenic sulfide slag is subjected to negative pressure distillation purification treatment in advance before mixing. Researches find that the negative pressure distillation purification treatment is more beneficial to the preparation of the simple substance arsenic and can greatly reduce the cost of the separation and utilization of the full components of the arsenic sulfide slag.

Preferably, the temperature of the negative pressure distillation purification treatment process is 400-600 ℃, and the pressure is 10-100 Pa. The time of the negative pressure distillation purification treatment can be determined according to the impurity (such as elemental sulfur, arsenic oxide and the like) condition of the arsenic sulfide slag.

In the invention, in order to successfully prepare the simple substance arsenic, the temperature needs to be controlled at 550 ℃ or above.

Preferably, the reaction temperature is not lower than 575 ℃, and more preferably is 575-.

The reaction is preferably carried out under a protective atmosphere, for example nitrogen or an inert gas.

Preferably, the reaction time is not less than 30 min; preferably 30-90 min.

In the present invention, preferably, the method of negative pressure distillation is adopted to recover the simple substance arsenic from the reaction product.

Preferably, the pressure of the negative pressure distillation process is 15-25 Pa; the temperature is 450-600 ℃.

Preferably, the negative pressure distillation time is not less than 60 min; preferably 60-90 min.

The invention also provides a method for recovering the simple substance arsenic from the arsenic sulfide slag, which takes the arsenic sulfide slag as an arsenic sulfide raw material, uses analytically pure calcium carbide as a metal carbide, and adopts the preparation method of the simple substance arsenic to treat the arsenic sulfide slag and produce the simple substance arsenic.

The invention discloses a preferable method for recovering simple substance arsenic from arsenic sulfide slag, which comprises the following steps:

(1) mixing and grinding arsenic sulfide and excessive calcium carbide powder, and reacting at 575-; the reaction time is preferably 30 to 90 min.

(2) Distilling the reaction product obtained in the step (1) under the conditions of the pressure of 15-25Pa and the temperature of 450-600 ℃ to obtain a condensate of simple substance arsenic; the distillation time is preferably 60-90 min.

The metal carbide of the invention takes calcium carbide as an example, and the preparation mechanism is as follows:

As₂S₃+3CaC₂＝2As+3CaS+6C (1)

as can be converted by the innovative preparation mechanism of the invention₂S₃High-efficiency conversion, and can directly obtain crystalline arsenic, and moreover, byproducts are not easy to generate, and the recovery rate of arsenic and the purity of the synthesized arsenic are higher.

The invention has the advantages of

1. The method of the invention provides a brand-new As₂S₃The conversion of the arsenic into elemental arsenic is discovered through research, the crystalline elemental arsenic can be unexpectedly prepared through the brand-new preparation mechanism, side reactions in the prior art can be avoided, the yield and purity of the product can be further improved, and the recovery rate of the arsenic is found to reach more than 98 percentThe purity can reach 100 percent by EDS. The method has the advantages of short process flow, easily controlled operation conditions, safe and environment-friendly whole process, and the obtained high-purity arsenic product can be directly applied to industry or further refined into high-purity arsenic for semiconductor industry. The raw material calcium carbide powder for reducing arsenic sulfide has high efficiency and relatively low price, and the cost for recovering arsenic is greatly reduced.

2. By adopting the method, the arsenic sulfide slag is recycled, and the simple substance arsenic is co-produced on the premise of realizing the high-efficiency treatment of the arsenic sulfide slag, so that a new technical scheme is provided for the resource utilization of the arsenic sulfide waste slag, the risk of stockpiled wastes is greatly reduced, and the method has remarkable economic benefit and environmental protection benefit, and is worthy of popularization and application.

Drawings

FIG. 1 is a diagram showing the results of XRD (X-ray diffractometer) measurement of the distillate obtained in example 1 of the present invention.

It can be seen from the figure that the boil-off is elemental arsenic.

FIG. 2 is a graph showing the results of detection by an EDS (energy dispersive X-ray fluorescence Spectroscopy) of the distillate obtained in example 1 of the present invention.

It can be seen from the figure that the obtained elemental arsenic has a high purity and no other impurities.

Detailed Description

The following examples are intended to illustrate the invention without further limiting it.

The arsenic sulfide slag (dry slag) of the experiment comprises the main components (wt.%) As 35.6, S36.12, Pb 1.15 and Ca9.29. The arsenic sulfide slag is distilled under 10-100Pa and 450 ℃ to remove a small amount of elemental sulfur and arsenic oxide in the arsenic sulfide slag, and the treated material is used as a pure arsenic sulfide raw material in the following cases.