Method for synthesizing mercuric sulfide by full-wet method

Abstract

The invention relates to a method for synthesizing mercuric sulfide by an all-wet method, which adopts industrial crude mercury and a sodium sulfide purified solution as raw materials, takes a solution phase controllable reaction as a core, breaks through the bottlenecks in raw material limitation, reaction conditions, product regulation and environmental protection in the prior art, and aims to solve the problems that the prior art depends on a high-temperature or high-pressure environment, the reaction process is uncontrollable and the like. And through precise regulation and control of solution phase parameters, mild reaction conditions and controllable process are realized, and the method is suitable for application scenes such as electronics and medicines. Crystal form orientation is realized through dual control of crystallization rate and additives, beta-HgS is generated through rapid crystallization, and alpha-HgS is generated through slow crystallization; the problem of mercury pollution or other toxic gas pollution in actual operation is solved, a traditional method for synthesizing mercuric sulfide from mercury and sulfur or hydrogen sulfide is replaced, and a low-pollution and low-energy-consumption synthesis method is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic compound preparation, in particular to a method for synthesizing mercuric sulfide by a full-wet method. BACKGROUND

[0002] Mercuric sulfide red, also known as sulfide salt of mercury, red mercuric sulfide, cinnabar, and vermilion, is a compound of a metal and a non-metal, having red hexagonal (or powder) and black cubic (or amorphous powder). Mercuric sulfide is toxic and insoluble in hydrochloric acid and nitric acid.

[0003] Mercuric sulfide has a wide range of applications, such as being used as a colorant for pigments, fire paint, preservatives, and traditional Chinese medicine preparation, and being used as a rubber pigment for the pharmaceutical industry and pigment manufacturing. The bright red pigment is mainly used for indoor coatings. It is also used as a red pigment for lacquer, ink, printing oil, and painting. Natural mercuric sulfide is the main raw material for manufacturing mercury. It is also used in colored wax sealing, plastics, rubber, medicine, and preservatives. As an important inorganic material, mercuric sulfide has wide application value in the fields of chemical industry, medicine, pesticide, dye, and electronic industry. Its unique chemical properties, excellent photoelectric performance, and wide application prospects make mercuric sulfide one of the important directions of current scientific research and technological innovation. In the future, with the continuous development of science and technology and the deepening of people's understanding of the performance of mercuric sulfide, its application in various fields will be more extensive and in-depth.

[0004] Among all mercury compounds, mercuric sulfide is the most important one. Cinnabar is one of the traditional products in the production of mercury industry in China. There are three production methods: first, the ore with high HgS grade and obvious cinnabar crystal body is mined from mercury deposits. After being crushed, the cinnabar is separated from the gangue by gravity separation method, and then the iron filings are removed by strong magnetic separation. After drying, the cinnabar is obtained by water flying (an operation process of washing cinnabar with water). The actual yield of cinnabar is generally 30%-35%. Most of the mercury mines in China use this method to produce cinnabar. The other two methods are artificial synthesis and wet method (i.e. chemical precipitation method), which can also be used to produce cinnabar. However, the former has serious mercury pollution, and the latter has not been widely used in industrial production. The following are several common methods for producing mercuric sulfide researched in recent years: (1) Sublimation method This is a traditional production method. Sulfur is melted and added to mercury in proportion, and a little water is added for stirring. Black particles are formed. Then, the black particles are calcined at 600°C to sublimate, and the sublimated material is cooled to obtain mercuric sulfide product.

[0005] (2) Wet production method Hydrogen sulfide is passed into a mercury salt solution to obtain black mercuric sulfide. The black mercuric sulfide is heated to sublimate, which can be converted into red mercuric sulfide.

[0006] (3) Anhydrous mercury chloride and lithium sulfide reaction method This is a relatively novel synthesis method, which can be carried out at a lower temperature. Anhydrous mercury chloride and lithium sulfide are loaded into a sealed reactor under vacuum or protective atmosphere, heated to 100-300 DEG C, and kept at a constant temperature for 0.1-100 h. After the reaction is completed, the solid product is separated and mercury sulfide is obtained.

[0007] (4) Preparation of nano mercury sulfide For applications that require the preparation of nano-sized mercury sulfide, sodium thiosulfate can be used as a raw material to synthesize mercury thiosulfate precursor by room temperature liquid phase reaction. The nano mercury sulfide is obtained by decomposing in an autoclave at a suitable temperature and pressure.

[0008] In view of the fact that the production of mercury sulfide requires high temperature or pressure, and in actual operation, there is a problem of mercury pollution or pollution by other toxic gases, the present application uses the solid-liquid deposition technology of industrial crude mercury and sodium sulfide purification liquid to replace the traditional method of synthesizing mercury sulfide from mercury and sulfur or hydrogen sulfide, forming a low-pollution and low-energy consumption synthesis method. SUMMARY

[0009] The present application uses industrial crude mercury and sodium sulfide purification liquid as raw materials, and takes "solution phase controllable reaction" as the core, breaking the bottleneck of the prior art in raw material limitation, reaction conditions, product control and environmental protection. In view of the fact that the prior art relies on high temperature or high pressure environment, and the reaction process is uncontrollable, through precise control of solution phase parameters, the reaction conditions are mild and the process is controllable, which is suitable for electronic, pharmaceutical and other application scenarios. Through the dual control of "crystallization rate + additives", the crystal form is oriented - β-HgS (excellent conductivity, suitable for sensors) is generated by rapid crystallization, and α-HgS (good photoelectric performance, suitable for infrared detection) is generated by slow crystallization; overcome the problem of mercury pollution or pollution by other toxic gases in actual operation, replace the traditional method of synthesizing mercury sulfide from mercury and sulfur or hydrogen sulfide, form a low-pollution and low-energy consumption synthesis method.

[0010] The present application is implemented by the following technical scheme: a method for synthesizing mercury sulfide by full wet process, comprising the following steps: (1) Purification of sulfur source A sulfide solution with a mass concentration of 10-50% is prepared, and hydrogen peroxide with a mass concentration of 0.1-5% is added and oxidized for 30-90 minutes to oxidize Fe 2+ to Fe 3+Slowly add 40% concentration of sodium hydroxide solution to the solution, control the pH value at 10-13, precipitate for 60-70 minutes, filter, and then adsorb the filtrate on D401 chelating resin, to ensure that the Fe≤0.005g / L and Mg≤0.002g / L in the purified sulfurization solution system; (2) Elemental mercury dissolution Prepare an oxidation-sulfurization solution system, mix the oxidant, S 2- and Hg 0 in a molar ratio of 1-3:1-5:1-8, control the temperature at ≥40℃, the stirring rate at 300-400rpm, and the reaction time at 4-12 hours, during which the pH value is controlled at ≥11 by using alkali, the elemental mercury is dissolved in the form of complex state into the solution by using alkali metal sulfide solution, and the dissolution rate is ≥98%; (3) Mercury sulfide precipitation Slowly add acid to the solution containing mercury sulfur complex, adjust the pH value of the solution to 1-6, and HgS2 2- is gradually dissociated and forms fine HgS particles, which are agglomerated into larger mercury sulfide crystals; (4) Precipitate washing Wash to remove the surface-adsorbed Na + and Cl - , and dry until the water content is ≤0.5%, to obtain mercury sulfide with a purity of ≥98.5%.

[0011] Further preferred technical solutions are that, in the step (1), the sulfide is one of sodium sulfide, sodium hydrosulfide and sodium thiosulfate.

[0012] Further preferred technical solutions are that, in the step (2), the elemental mercury Hg 0 has a purity of ≥99.9%.

[0013] Further preferred technical solutions are that, in the step (2), the oxidant is one of oxygen, hydrogen peroxide, sodium chlorate and sodium hypochlorite.

[0014] Further preferred technical solutions are that, in the step (3), when the mercury concentration in the supernatant is ≤0.1mg / L, it is determined that the precipitation is complete.

[0015] Further preferred technical solutions are that, in the step (4), the surface-adsorbed Na + and Cl - are removed by washing with deionized water for 3-5 times; and finally, the washing is performed once with anhydrous ethanol, the temperature is controlled at 60-90℃, and the drying time is 10-15h.

[0016] The present application has the following advantages: 1. The HgS precipitation rate is ≥98%, and the purity is ≥98.5%.

[0017] 2. In the traditional synthesis process of mercury sulfide, it is often difficult to avoid the mixing of impurities due to the limitations of reaction conditions and raw materials. The present application has a significant advantage in reducing the mixing of impurities; 3. In some traditional synthesis processes, mercury-containing wastewater, waste gas and waste residue are generated. The reaction system of the present application is relatively closed, which can effectively reduce the generation of harmful by-products. Compared with traditional technology, the present application also has obvious environmental protection advantages in the process of product separation and purification. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the specific embodiments, structures, features and effects according to the present application are described in detail as follows.

[0019] The present embodiment provides a method for synthesizing mercury sulfide by full wet process, I. Control conditions: The purity and form of the raw material system are the basis of the synthesis reaction, and the purity of mercury source, the selection of sulfur source and the pretreatment of impurities need to be controlled to avoid interference in the subsequent reaction.

[0020] (1) Elemental mercury (Hg 0 ) purity ≥ 99.9%.

[0021] (2) Sulfur source is sodium sulfide, sodium hydrosulfide or sodium thiosulfate, etc.

[0022] II. The synthesis steps are as follows: Example 1

[0023] Step 1: Sulfur source purification For the Fe 0.1%~0.5%, Mg 0.05%~0.2% contained in the industrial grade sulfide solution system, based on the solubility product difference of iron, magnesium ions and other ions in the sulfide solution system, the separation is realized by "chemical precipitation-depth adsorption" combined process, and the deep purification of sulfur source is realized. 10% sodium sulfide solution is configured, 1% hydrogen peroxide is added and oxidized for 30 minutes, Fe 2+ is oxidized to Fe 3+ , and then 40% concentration of sodium hydroxide (NaOH) solution is slowly added to the solution, the pH value is controlled at 10, and the precipitation reaction is filtered for 60 minutes. After filtration, it is adsorbed by D401 chelating resin to ensure that the Fe in the purified sulfide solution system is ≤0.005 g / L and Mg is ≤0.002 g / L.

[0024] Step 2: Elemental mercury dissolution Based on the low chemical activity of elemental mercury itself (standard electrode potential E°(Hg 2Mercury (Hg) = 0.851V cannot react directly with low-concentration sodium sulfide solution; oxidative dissolution conditions must be created by controlling the solution environment. In preparing an oxidation-sulfide solution system, the oxidant is the "key trigger" for the dissolution of elemental mercury and must be stable in the sulfide solution and not react with sulfur. 2- Oxidizing agents that react violently include, but are not limited to, oxygen, hydrogen peroxide, sodium chlorate, and sodium hypochlorite. This embodiment will be described according to oxygen, S... 2- With Hg 0 Mix thoroughly at a molar ratio of 1:1:2, maintain a temperature ≥40℃, a stirring speed of 300 rpm, and a reaction time of 4 hours, during which the pH is maintained at ≥11 using alkali. At this point, elemental mercury dissolves in the alkali metal sulfide solution to form a complex state (such as Na2HgS2) and enters the solution, with a solubility ≥98%.

[0025] Step 3: Mercuric sulfide precipitation Slowly add hydrochloric acid to the solution containing the mercury-sulfur complex to adjust the pH to 1. At this point, HgS2 2- The mercury gradually dissociates and forms fine HgS particles, which then aggregate into larger mercury sulfide crystals. The mercury concentration in the supernatant is determined by atomic fluorescence spectrometry; precipitation is considered complete when the concentration is ≤0.1 mg / L.

[0026] Step 4: Sedimentation and Washing Wash three times with deionized water at pH 7 to remove adsorbed Na from the surface. + Cl - Finally, it was washed once with anhydrous ethanol and dried at 60℃ for 10 hours to ensure that the moisture content was ≤0.5%, thus obtaining mercuric sulfide with a purity of 98.5%. Example 2

[0027] Step 1: Sulfur source purification Prepare a 30% sodium hydrosulfide solution, add 3% hydrogen peroxide, and oxidize for 60 minutes to remove Fe. 2+ Oxidized to Fe 3+ Then, slowly add a 40% sodium hydroxide solution dropwise to the solution, controlling the pH value at 12, and allow the precipitation reaction to proceed for 70 minutes before filtration. The filtered solution is then adsorbed onto a D401 type isochelating resin to ensure that the purified sulfurized solution system contains Fe ≤ 0.005 g / L and Mg ≤ 0.002 g / L.

[0028] Step 2: Dissolving elemental mercury According to hydrogen peroxide, S 2- With Hg 0 Mix the mercury in a molar ratio of 3:5:8 until homogeneous, maintain a temperature ≥40℃, a stirring speed of 400 rpm, and a reaction time of 12 hours, during which the pH is maintained at ≥11 using alkali. At this point, elemental mercury dissolves in the alkali metal sulfide solution to form a complex and enters the solution, with a solubility ≥98%.

[0029] Step 3: Mercury sulfide precipitation Slowly add sulfuric acid to the solution containing mercury sulfur complex, adjust the solution pH to 6, at this time HgS2 2- Gradually dissociate and generate fine HgS particles, which agglomerate into larger mercury sulfide crystals. The mercury concentration in the supernatant is ≤0.1 mg / L (atomic fluorescence spectrometry), which is determined to be completely precipitated.

[0030] Step 4: Precipitate washing Wash 5 times with deionized water pH 7 to remove surface-adsorbed Na + , Cl - ; finally wash once with anhydrous ethanol, dry at a temperature controlled at 90°C for 15h, ensure the water content ≤0.5%, get mercury sulfide with purity of 99.2%. Example 3

[0031] Step 1: Purification of sulfur source Prepare a 50% sodium thiosulfate solution, add 5% hydrogen peroxide and oxidize for 90 minutes, oxidize Fe 2+ to Fe 3+ , then slowly add 40% sodium hydroxide (NaOH) solution to the solution, control the pH value to 13, precipitate for 70 minutes and filter. After filtration, the liquid is adsorbed by D401 type chelating resin to ensure that the Fe content in the purified sulfur solution system is ≤0.005 g / L and the Mg content is ≤0.002 g / L.

[0032] Step 2: Mercury dissolution Mix sodium hypochlorite, S 2- and Hg 0 in a molar ratio of 3:3:5, control the temperature to ≥40°C, the stirring rate is 400 rpm, the reaction time is 8 hours, and the pH is controlled to ≥11 with alkali during the reaction. At this time, the elemental mercury is dissolved in the form of alkali metal sulfide solution to form a complex state in the solution, and the dissolution rate is ≥98%.

[0033] Step 3: Mercury sulfide precipitation Slowly add hydrochloric acid to the solution containing mercury sulfur complex, adjust the solution pH to 3, at this time HgS2 2- Gradually dissociate and generate fine HgS particles, which agglomerate into larger mercury sulfide crystals. The mercury concentration in the supernatant is ≤0.1 mg / L (atomic fluorescence spectrometry), which is determined to be completely precipitated.

[0034] Step 4: Precipitate washing Wash 5 times with deionized water pH 8 to remove surface-adsorbed Na + , Cl -; last washed once with anhydrous ethanol, dried at a temperature controlled at 80°C for 13h, ensuring a water content ≤ 0.5%, obtaining mercury sulphide with a purity of 98.8%.

[0035] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with preferred embodiments as above, it is not intended to limit the present application. Any person skilled in the art, without departing from the technical solution of the present application, can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes. However, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the technical solution of the present application, still falls within the scope of the technical solution of the present application.

Claims

1. A method for the all-wet synthesis of mercuric sulfide, characterized in that, Includes the following steps: (1) Sulfur source purification Prepare a sulfide solution with a mass concentration of 10-50%, add hydrogen peroxide with a mass concentration of 0.1-5%, and oxidize for 30-90 minutes to remove Fe. 2+ Oxidized to Fe 3+ Then, slowly add a 40% sodium hydroxide solution to the solution, control the pH value at 10-13, allow the precipitation reaction to proceed for 60-70 minutes, filter, and then adsorb the filtrate with D401 chelating resin to ensure that Fe≤0.005g / L and Mg≤0.002g / L in the purified sulfidation solution system. (2) Dissolution of elemental mercury Prepare an oxidation-sulfurization solution system, and add oxidant and sulfur. 2- With Hg 0 Mix thoroughly at a molar ratio of 1-3:1-5:1-8, control the temperature at ≥40℃, stir at 300-400rpm, and react for 4-12 hours. During this period, use alkali to control the pH at ≥11. Elemental mercury dissolves in alkali metal sulfide solution to form a complex and enters the solution, with a solubility rate of ≥98%. (3) Mercuric sulfide precipitation Slowly add acid to the solution containing mercury-sulfur complex to adjust the pH of the solution to 1-6. (HgS2) 2- Gradually dissociate and generate fine HgS particles that agglomerate into larger mercury sulfide crystals; (4) Precipitation and washing Washing removes adsorbed Na from the surface + Cl - The mercury sulfide was dried until the moisture content was ≤0.5% to obtain mercury sulfide with a purity of ≥98.5%.

2. The method for synthesizing mercuric sulfide using a fully wet process according to claim 1, characterized in that, In step (1), the sulfide is one of sodium sulfide, sodium hydrosulfide, or sodium thiosulfate.

3. The method for synthesizing mercuric sulfide using a fully wet process according to claim 1, characterized in that, In step (2), elemental mercury Hg 0 Purity ≥ 99.9%.

4. The method for synthesizing mercuric sulfide using a fully wet process according to claim 1, characterized in that, In step (2), the oxidant is one of oxygen, hydrogen peroxide, sodium chlorate, or sodium hypochlorite.

5. The method for synthesizing mercuric sulfide using a fully wet process according to claim 1, characterized in that, In step (3), precipitation is considered complete when the mercury concentration in the supernatant is ≤0.1mg / L.

6. The method for synthesizing mercuric sulfide using a fully wet process according to claim 1, characterized in that, In step (4), the surface is washed 3-5 times with deionized water to remove adsorbed Na. + Cl - Finally, wash once with anhydrous ethanol, and dry at 60~90℃ for 10~15 hours.