阅读说明：本技术 一种从粗硒中脱除杂质汞的方法 (Method for removing impurity mercury from crude selenium ) 是由 徐宝强 罗欢 杨斌 蒋文龙 刘浪 查国正 熊恒 田阳 孔令鑫 李一夫 王飞 杨 于 2021-09-13 设计创作，主要内容包括：本发明公开一种粗硒中脱除杂质汞的方法,属于稀散金属提纯脱杂技术领域。本发明所述方法为：向破碎至200目以下的粗硒渣中加入硫化剂,均匀混合压块得到混合物料,将混合物料放入密闭炉,在惰性气氛下加热硫化；硫化后的硒进行真空蒸馏,硒进入气相以挥发物的形式被收集,生成汞的硫化物以及有价元素富集进入残留物；然后为了进一步脱汞将得到硒进行二次蒸馏。本发明所述方法工艺简单,过程安全可控,操作方便,最终硒产品中汞含量小于5ppm,硒的直收率大于96%,汞的脱除率大于99.8%。(The invention discloses a method for removing impurity mercury from crude selenium, belonging to the technical field of rare dispersion metal purification and impurity removal. The method comprises the following steps: adding a vulcanizing agent into the crude selenium slag crushed to be below 200 meshes, uniformly mixing and briquetting to obtain a mixed material, putting the mixed material into a closed furnace, and heating and vulcanizing under an inert atmosphere; vacuum distillation is carried out on the selenium after sulfuration, the selenium enters a gas phase and is collected in the form of volatile matters, and sulfide of mercury and valuable elements are generated and enter residues after being enriched; the selenium obtained is then subjected to a secondary distillation for further demercuration. The method has the advantages of simple process, safe and controllable process and convenient operation, and the final selenium product has the mercury content of less than 5ppm, the direct yield of selenium of more than 96 percent and the removal rate of mercury of more than 99.8 percent.)

1. A method for removing impurity mercury from crude selenium is characterized by comprising the following steps: adding a vulcanizing agent into the crushed crude selenium slag, uniformly mixing and briquetting to obtain a mixed material, putting the mixed material into a closed furnace, and heating and vulcanizing under an inert atmosphere; vacuum distillation is carried out on the selenium after sulfuration, the selenium enters a gas phase and is collected in the form of volatile matters, and the generated mercury sulfide and valuable elements are enriched in residues; the selenium obtained is then subjected to a secondary distillation for further demercuration.

2. The method for removing impurity mercury from crude selenium according to claim 1, wherein: crushing the crude selenium powder to below 200 meshes, and briquetting under the pressure of 4-8 Mpa after mixing.

3. The method for removing impurity mercury from crude selenium according to claim 1, wherein: the molar ratio of mercury to sulfur in the vulcanization reaction stage is 1: 10-1: 20; the vulcanizing agent is elemental sulfur or sulfide.

4. The method for removing impurity mercury from crude selenium according to claim 1, wherein: under inert atmosphere, the vulcanization temperature is 150-300 ℃, the reaction time is 15-60 min, and the heating rate is 5-25 ℃/min.

5. The method for removing impurity mercury from crude selenium according to claim 1, wherein: the temperature of the primary vacuum distillation is 240-280 ℃, the pressure is 1-30 Pa, the reaction time is 20-100 min, and the heating rate is 5-25 ℃/min.

6. The method for removing impurity mercury from crude selenium according to claim 1, wherein: the secondary vacuum distillation temperature is 200-250 ℃, the pressure is 1-10 Pa, the reaction time is 30-60 min, and the temperature rise rate is 5-25 ℃/min.

Technical Field

The invention relates to a method for removing impurity mercury from crude selenium, belonging to the technical field of rare dispersion metal purification and impurity removal.

Technical Field

Selenium has excellent physical and chemical properties and is widely applied in the high-tech field, but in the process of purifying selenium, the content of selenium products is higher due to the volatility of mercury, and the quality of the selenium products is seriously influenced. Mercury is also classified as a hazardous waste due to its high toxicity, bio-accumulation, and is recognized globally as threatening human and environmental health. Therefore, the removal of mercury from the crude selenium waste is a key problem to be solved urgently in the development of the selenium industry.

At present, the methods for removing mercury from crude selenium mainly comprise a wet precipitation process and a pyrogenic distillation process. The wet precipitation process is already applied, and the typical process mainly comprises hydrochloric acid-NaClO oxidation and Na₂SO₃Reducing selenium and hydrazine hydrate to obtain Se and HgCl₂. The recovery rate of selenium and mercury is high, but the problems of long process flow, high cost, small market and the like exist. The pyrogenic distillation process is the most widely used treatment process for removing harmful impurity mercury from selenium-containing waste at present. The process comprises pretreatment (lime addition, granulation, drying), roasting distillation, condensation and purification. The specific process comprises adding calcium to extract selenium, and combining selenium in the material with CaO to form a compositeVolatile CaSeO₃Separating selenium from mercury, leaching, purifying the solution to remove mercury, SO₂Reducing selenium. In order to separate mercury from selenium in the process, a large amount of lime needs to be added, so that the energy consumption is high, the cost is high, and the process is complex.

CN105039747A discloses a method for separating selenium and mercury from acid sludge produced by roasting gold concentrate, which comprises the steps of adding concentrated sulfuric acid into a material for producing acid sludge by roasting gold concentrate, mixing the concentrated sulfuric acid into the material, adding a catalyst A, stirring the mixture uniformly, carrying out catalytic oxidation roasting to obtain roasted flue gas and roasted slag, introducing the roasted flue gas into a tail gas absorption system, wherein an absorption solution is an alkali solution, after the flue gas absorption is finished, obtaining mercury concentrate and a selenium-containing solution, realizing selenium and mercury separation, and then adding sulfuric acid into the selenium-containing alkali solution to form sulfurous acid and sodium selenite to directly carry out a reduction reaction, so as to obtain crude selenium and a reduced solution; returning the reduced solution to the selenium-containing alkali liquor for secondary reduction. The invention has complex process, needs to repeatedly oxidize and reduce selenium, and has larger reagent consumption and higher cost.

Disclosure of Invention

The invention provides a method for removing impurity mercury from crude selenium, which has the advantages of simple process, safe and controllable process, convenient operation, direct selenium yield of more than 98 percent and mercury removal rate of more than 99.8 percent.

The technical scheme of the invention is as follows: adding a vulcanizing agent into the crude selenium slag crushed to be below 200 meshes, uniformly mixing and briquetting to obtain a mixed material, putting the mixed material into a closed furnace, and heating and vulcanizing under an inert atmosphere; vacuum distillation is carried out on the selenium after sulfuration, the selenium enters a gas phase and is collected in the form of volatile matters, and the generated mercury sulfide and valuable elements are enriched in residues; the selenium obtained is then subjected to a secondary distillation for further demercuration.

Preferably, the crude selenium powder is crushed to below 200 meshes, and when the particle size of the crude selenium is in the range, the crude selenium powder is directly used; and when the particle size of the crude selenium raw material does not meet the range, crushing the crude selenium raw material.

Preferably, the pressure of the mixed briquetting is 4-8 Mpa, the purpose of briquetting is to inhibit volatilization of the vulcanizing agent, and the crude selenium and the vulcanizing agent can be uniformly mixed and then briquetted, so that the contact area of the vulcanizing agent and mercury selenide can be increased, and the rate of replacement reaction is increased; sulfur becomes gaseous and flows between the pores of the bulk feed during sulfidizing smelting, which facilitates contact between the reactants.

Preferably, the molar ratio of mercury to sulfur in the vulcanization reaction stage is 1: 10-1: 20. The vulcanizing agent can be elemental sulfur or sulfide, and the sulfide can be sodium sulfide, ferric sulfide, ferrous disulfide and the like.

Preferably, the vulcanization temperature is 150-300 ℃, and the reaction time is 15-60 min.

Preferably, the primary vacuum distillation temperature is 240-280 ℃, the pressure is 1-30 Pa, and the reaction time is 20-100 min.

Preferably, the secondary vacuum distillation temperature is 200-250 ℃, the pressure is 1-10 Pa, and the reaction time is 30-60 min.

In the invention, the heating rate of heating to the vulcanization temperature and the vacuum distillation temperature is 5-25 ℃/min, and more preferably 5-15 ℃/min; the invention controls the sulfuration temperature and the heating rate of vacuum distillation within the above range, which is beneficial to fully reacting sulfur and mercury.

The mass fraction of Se in the crude selenium is 90-97%, the mass fraction of Hg is 3200ppm, and the mass fraction of Pb is 2-2.5%.

In the invention, the product of vacuum distillation is selenium, and the sulfide product is subjected to vacuum distillation to obtain a residue and a volatile matter, wherein the residue is the enrichment of mercury sulfide and valuable elements, and the volatile matter is selenium which escapes upwards to a condensation disc in a vacuum furnace and is obtained by condensation.

The principle of the invention is as follows: because mercury in the crude selenium mainly exists in the form of mercury selenide, and the saturated vapor pressure of the mercury selenide is similar to that of the selenium, the mercury cannot be removed by adopting single vacuum distillation; therefore, by utilizing the affinity difference between the metal mercury and selenium and sulfur or sulfide, the mercury and the sulfur are more easily combined so as to easily replace the selenium in the mercury selenide, the generated mercury sulfide and selenium have larger saturated vapor pressure difference, and then the obtained sulfide product is subjected to vacuum distillation so as to realize the separation of the selenium and the mercury sulfide; finally, selenium enters a gas phase to be collected in the form of volatile matters, and generated mercuric sulfide and valuable elements are enriched into residues; and further carrying out secondary distillation on the condensate selenium to deeply remove the impurity mercury.

The invention has the beneficial effects that: adding a vulcanizing agent into crude selenium slag crushed to be less than 200 meshes, uniformly mixing and briquetting to obtain a mixed material, putting the mixed material into a vacuum furnace for heating, and separating selenium from mercury by a vulcanization-vacuum distillation method mainly according to the characteristics that the affinity of metal mercury, selenium and sulfur or sulfide is different, and the saturated vapor pressure of the generated mercury sulfide and selenium is different; finally, selenium enters a gas phase and is collected in the form of volatile matters, and mercury sulfide and valuable elements are generated and enter residues in an enriched mode; the method has the advantages of simple process, safe and controllable process and convenient operation, the content of impurity mercury in the finally obtained selenium product is less than 5ppm, the requirement of the content of impurity mercury in a 3N selenium product is met, the direct selenium yield is more than 96%, and the mercury removal rate is more than 99.8%.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The invention provides a method for removing impurity mercury from crude selenium, and the technical scheme of the invention is clearly and completely described below by combining the embodiment of the invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A method for removing impurity mercury from crude selenium specifically comprises the following steps:

(1) crushing 50g of selenium-containing waste (mercury content 3200 ppm) into powder of below 200 meshes; uniformly mixing the obtained powder with sulfur (according to the mol ratio of mercury to sulfur of 1: 10-1: 20), and briquetting under the pressure of 4 Mpa; putting the mixed material into a closed furnace, and vulcanizing for 60min at the temperature of 150 ℃ and the heating rate of 5 ℃/min in an inert atmosphere to obtain a vulcanized product.

(2) Directly carrying out vacuum distillation on the obtained vulcanized product under the conditions that the heating rate is 5 ℃/min, the temperature is 240 ℃ and the pressure is 1Pa, reacting for 100min, and separating selenium from mercury by a vulcanization-vacuum distillation method according to the characteristics that the affinity of metal mercury, selenium and sulfur is different, and the saturated vapor pressure of the generated mercury sulfide and selenium is different; finally, selenium enters a gas phase and is collected in the form of volatile matters, and mercury sulfide and valuable elements are generated and enter residues in an enriched mode; 47.87g of selenium product is obtained, and the volatilization rate reaches 91.74%; the volatile selenium is detected, wherein the mercury content is 74.43ppm, and the removal rate reaches 97.67%.

(3) And carrying out secondary vacuum distillation on the obtained condensate selenium under the conditions that the temperature rise rate is 5 ℃/min and the vacuum distillation conditions are as follows: obtaining 47.6g of selenium product with the volatilization rate of 99.5 percent at 200 ℃ for 30min under 1 Pa; and (3) detecting volatile selenium, wherein the mercury content is 5ppm, the requirement of impurity mercury content in a 3N selenium product is met, and the removal rate reaches 99.8%.

Example 2

A method for removing impurity mercury from crude selenium specifically comprises the following steps:

(1) crushing 50g of selenium-containing waste (mercury content 3200 ppm) into powder of below 200 meshes; uniformly mixing the obtained powder with iron sulfide (the mol ratio of mercury to iron sulfide is 1: 15), and briquetting under the pressure of 6 Mpa; putting the mixed material into a closed furnace, and vulcanizing for 45min at the temperature of 200 ℃ and the heating rate of 10 ℃/min in an inert atmosphere to obtain a vulcanized product.

(2) Directly carrying out vacuum distillation on the obtained vulcanized product under the conditions that the temperature rising rate is 10 ℃/min, the temperature is 260 ℃ and the pressure is 10Pa, reacting for 80min, and separating selenium from mercury by a vulcanization-vacuum distillation method according to the characteristics that the affinity of metal mercury, selenium and ferric sulfide is different, and the saturated vapor pressure of the generated mercury sulfide and selenium is different; finally, selenium enters the gas phase and is collected in the form of volatile matter, mercury sulfide is generated, and valuable elements are enriched into the residue. 48.53g of selenium product was obtained; the recovery rate reaches 92.71 percent; the volatile selenium is detected, wherein the mercury content is 86.72ppm, and the removal rate reaches 95.94%.

(3) And carrying out secondary vacuum distillation on the obtained condensate selenium under the conditions that the temperature rise rate is 10 ℃/min and the vacuum distillation conditions are as follows: at 220 ℃, 40min and 5Pa, 48.3g of selenium product is obtained, and the volatilization rate reaches 99.7 percent; and (3) detecting a volatile selenium, wherein the mercury content is 7ppm, the requirement of the content of impurity mercury in a 3N selenium product is met, and the removal rate reaches 99.7%.

Example 3

A method for removing impurity mercury from crude selenium specifically comprises the following steps:

(1) crushing 50g of selenium-containing waste (mercury content 3200 ppm) into powder of below 200 meshes; mixing the obtained powder with sodium sulfide (at a molar ratio of mercury to sodium sulfide of 1: 10), and briquetting under 8 Mpa; and putting the mixed material into a closed furnace, and vulcanizing for 30min at the temperature of 250 ℃ and the heating rate of 15 ℃/min in an inert atmosphere to obtain a vulcanized product.

(2) Directly carrying out vacuum distillation on the obtained vulcanized product under the conditions that the temperature rise rate is 15 ℃/min, the temperature is 280 ℃ and the pressure is 20Pa, reacting for 20min, and separating selenium from mercury by a vulcanization-vacuum distillation method according to the characteristics that the affinity of metal mercury, selenium and sodium sulfide is different, and the saturated vapor pressure of the generated mercury sulfide and selenium is different; finally, selenium enters the gas phase and is collected in the form of volatile matter, mercury sulfide is generated, and valuable elements are enriched into the residue. 46.25g of selenium product was obtained; the recovery rate reaches 92.51 percent; and (3) detecting the volatile selenium, wherein the mercury content is 151ppm, and the removal rate reaches 95.28%.

(3) And carrying out secondary vacuum distillation on the obtained condensate selenium under the conditions that the temperature rise rate is 15 ℃/min and the vacuum distillation conditions are as follows: at 230 ℃, 50min and 10Pa, 46.1g of selenium product is obtained, and the volatilization rate reaches 99.8 percent; and (3) detecting the volatile selenium, wherein the mercury content is 15ppm, and the removal rate reaches 99.5%.

Example 4

A method for removing impurity mercury from crude selenium specifically comprises the following steps:

(1) crushing 50g of selenium-containing waste (mercury content 3200 ppm) into powder of below 200 meshes; uniformly mixing the obtained powder with ferrous disulfide (according to the mol ratio of mercury to ferrous disulfide being 1: 20), and briquetting under the pressure of 8 Mpa; and putting the mixed material into a closed furnace, and vulcanizing for 15min at the temperature of 300 ℃ at the heating rate of 5 ℃/min under the inert atmosphere to obtain a vulcanized product.

(2) Directly carrying out vacuum distillation on the obtained vulcanized product under the conditions that the temperature rise rate is 5 ℃/min, the temperature is 280 ℃ and the pressure is 30Pa, reacting for 40min, and separating selenium from mercury by a vulcanization-vacuum distillation method according to the characteristics that the affinity of metal mercury, selenium and ferrous disulfide is different, and the saturated vapor pressure of the generated mercury sulfide and selenium is different; finally, selenium enters the gas phase and is collected in the form of volatile matter, mercury sulfide is generated, and valuable elements are enriched into the residue. 46.25g of selenium product was obtained; the recovery rate reaches 96.15 percent; and (3) detecting the volatile selenium, wherein the mercury content is 201ppm, and the removal rate reaches 93.72%.

(3) And carrying out secondary vacuum distillation on the obtained condensate selenium under the conditions that the temperature rise rate is 10 ℃/min and the vacuum distillation conditions are as follows: at 250 ℃, 60min and 1Pa, 46.3g of selenium product is obtained, and the volatilization rate reaches 99.7 percent; the volatile selenium is detected, wherein the mercury content is 18ppm, and the removal rate reaches 99.4%.

Example 5

Comparative experiment: firstly, 50g of selenium-containing waste (mercury content of 3200 ppm) is crushed into powder with the granularity of less than 200 meshes; directly carrying out vacuum distillation under the conditions that the temperature rise rate is 10 ℃/min, the temperature is 300 ℃ and the pressure is 30Pa, reacting for 30min, and collecting the selenium entering the gas phase in the form of volatile matters. The volatilization rate of selenium is 64.8 percent, and the recovery rate reaches 84.6 percent; and (3) detecting volatile selenium, wherein the mercury content is 1381ppm, the removal rate reaches 43.15%, and other valuable elements are enriched in residues.

In summary, according to the method for removing the impurity mercury from the crude selenium provided by the invention, the vulcanizing agent is added into the crude selenium slag which is crushed to be below 200 meshes, the mixture is uniformly mixed and pressed into blocks to obtain a mixed material, the mixed material is placed into a closed furnace, and the heating and the vulcanizing are carried out under the inert atmosphere; vacuum distillation is carried out on the selenium after sulfuration, the selenium enters a gas phase and is collected in the form of volatile matters, and sulfide of mercury and valuable elements are generated and enter residues after being enriched; the selenium obtained is then subjected to a secondary distillation for further demercuration.

The method has the advantages of simple process, safe and controllable process and convenient operation, the content of impurity mercury in the finally obtained selenium product is less than 5ppm, the requirement of the content of impurity mercury in a 3N selenium product is met, the direct selenium yield is more than 96%, the mercury removal rate is more than 99.8%, and other valuable elements are enriched in residues.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.