阅读说明：本技术 粗碲的提纯回收工艺 (Purification and recovery process of crude tellurium ) 是由 罗鑫 陈应红 王波 梁鉴华 于 2020-12-09 设计创作，主要内容包括：本公开提供一种粗碲的提纯回收工艺,其包括步骤：步骤一,酸性氧化：将粗碲加入装有水的装置配成悬浊液,然后向其中加入盐酸调节pH值在0.6～2之间,再向该装置中加入氯酸钠升温至80～85℃氧化,最终pH控制在3～5,搅拌1h～2h；步骤二,压滤：氧化结束后进行压滤,得到滤液和滤渣,滤渣为碲料；步骤三,滤渣除杂：碲料中加入氢氧化钠调节pH≥14搅拌2～3h,再加入硫化钠溶液除去溶液中的除碲外的重金属,再进行压滤,得到除杂液和滤渣；步骤四,除杂液电解：除杂液分析合格压滤清亮后,除杂滤液转入电解槽开始电解,之后电解出的碲经过洗涤烘干后即得到单质碲。本公开的方法流程短、简便易行、工艺稳定、碲直收率高、得到的碲锭纯度高。(The present disclosure provides a process for purifying and recovering crude tellurium, which comprises the steps of: step one, acid oxidation: adding the crude tellurium into a device filled with water to prepare a suspension, adding hydrochloric acid into the suspension to adjust the pH value to be 0.6-2, adding sodium chlorate into the device, heating to 80-85 ℃ for oxidation, controlling the pH value to be 3-5, and stirring for 1-2 hours; step two, filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residues, wherein the filter residues are tellurium materials; step three, filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to be more than or equal to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues; step four, electrolyzing impurity removing liquid: and (4) after the impurity removal liquid is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain the simple substance tellurium. The method disclosed by the invention has the advantages of short flow, simplicity, convenience, easiness, stable process, high tellurium direct yield and high purity of the obtained tellurium ingot.)

1. A process for purifying and recovering crude tellurium is characterized by comprising the following steps:

step one, acid oxidation: adding the crude tellurium into a device filled with water to prepare a suspension, adding hydrochloric acid into the suspension to adjust the pH value to be 0.6-1, adding sodium chlorate into the device, heating to 80-85 ℃ for oxidation, controlling the pH value to be 3-4, and stirring for 1-2 hours;

step two, filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residues, wherein the filter residues are tellurium materials;

step three, filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to be more than or equal to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues;

step four, electrolyzing impurity removing liquid: and (4) after the impurity removal liquid is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain the simple substance tellurium.

2. The process of claim 1, wherein in step one, the raw materials are fed in a solid-to-liquid ratio of (1:4) - (1:5), and the device filled with water is a stirred tank.

3. The process of claim 1, wherein in the first step, the mass ratio of tellurium to sodium chlorate is (1:0.3) - (1: 0.53).

4. The process of claim 1, wherein in step three, sodium hydroxide is added to adjust the pH to 14.

5. The process for purifying and recovering crude tellurium according to claim 1, wherein in the third step, stirring is carried out for 2 hours.

6. The process of claim 1, wherein in step three, the amount of the sodium sulfide solution added is reacted until the content of copper, lead and bismuth in the solution is less than 2 ppm.

7. The process of claim 1, wherein the heavy metals in step three include Cu, Pb and Bi.

8. The process of claim 1, wherein in step four, the solution for washing the tellurium metal is water.

9. The process of claim 1, wherein in step four, the drying is performed at a temperature of not higher than 100 ℃.

10. The process of purifying and recovering crude tellurium as claimed in claim 1, wherein the process of purifying and recovering crude tellurium further comprises:

and fifthly, carrying out melt casting molding on the washed and dried simple substance tellurium.

Technical Field

The disclosure relates to the technical field of non-ferrous metal smelting, and more particularly relates to a process for purifying and recovering crude tellurium.

Background

Tellurium is a basic material for the preparation of compound semiconductor materials, for example cadmium telluride can be used in the manufacture of light emitting diodes, radiation detectors and solar cells; the tellurium-mercury-cadmium alloy is the best material for the infrared emitter and the detector; the tellurium-bismuth-selenium-antimony alloy is an important thermoelectric material for generating electricity and refrigerating, such as refrigerating of civil products such as water dispensers, refrigerators, air conditioners and the like, and can also be used in space power systems, aviation, high-altitude weather recording instruments, military radar coolers and submarine air conditioners.

The tellurium in the crude tellurium exists mainly in a 0-valent form, and the leaching rate of the tellurium often greatly influences the recovery rate of the tellurium. Crude tellurium can be used as an important raw material for extracting tellurium, and the main components of the crude tellurium comprise: 70 to 99 percent of Te, 0.1 to 1 percent of Se and the water content is less than 30 percent. Therefore, the technical problem to be solved by the research in the technical field is to establish a tellurium purification process method which is low in cost, short in flow, simple and easy to implement, stable in process, high in tellurium direct yield and high in purity of the obtained tellurium ingot.

Disclosure of Invention

In view of the problems in the background art, the present disclosure aims to provide a process for purifying and recovering crude tellurium, which can obtain elemental tellurium with high purity.

In order to achieve the above object, the present disclosure provides a process for purifying and recovering crude tellurium, which comprises the steps of: step one, acid oxidation: adding the crude tellurium into a device filled with water to prepare a suspension, adding hydrochloric acid into the suspension to adjust the pH value to be 0.6-2, adding sodium chlorate into the device, heating to 80-85 ℃ for oxidation, controlling the pH value to be 3-5, and stirring for 1-2 hours; step two, filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residues, wherein the filter residues are tellurium materials; step three, filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to be more than or equal to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues; step four, electrolyzing impurity removing liquid: and (4) after the impurity removal liquid is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain the simple substance tellurium.

In some embodiments, in the first step, the raw materials are fed according to the solid-to-liquid ratio (1:4) - (1:5), and the device filled with water is a stirring kettle.

In some embodiments, in step one, the mass of tellurium to mass of sodium chlorate is (1:0.3) to (1: 0.54).

In some embodiments, in step three, sodium hydroxide is added to adjust the pH to 14.

In some embodiments, in step three, stirring is for 2 h.

In some embodiments, in step three, the amount of sodium sulfide solution added reacts until the copper, lead, bismuth content in the solution is less than 2 ppm.

In some embodiments, the heavy metals in step three include Cu, Pb, Bi.

In some embodiments, in step four, the solution for washing tellurium metal is water.

In some embodiments, in step four, the drying is performed at a temperature of not higher than 100 ℃.

In some embodiments, step five, the washed and dried elemental tellurium is formed by melt casting.

The beneficial effects of this disclosure are as follows:

the purification and recovery process of the crude tellurium disclosed by the invention is short in flow, simple and easy to implement, stable in process, high in direct tellurium yield and high in purity of the obtained tellurium ingot.

Detailed Description

The process for purifying and recovering crude tellurium according to the present disclosure is explained in detail as follows.

The process for purifying and recovering the crude tellurium comprises the following steps: step one, acid oxidation: adding the crude tellurium into a device filled with water to prepare a suspension, adding hydrochloric acid into the suspension to adjust the pH value to be 0.6-2, adding sodium chlorate into the device, heating to 80-85 ℃ for oxidation, controlling the pH value to be 3-5, and stirring for 1-2 hours; step two, filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residues, wherein the filter residues are tellurium materials; step three, filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to be more than or equal to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues; step four, electrolyzing impurity removing liquid: and (4) after the impurity removal liquid is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain the simple substance tellurium.

Wherein, the main components of the crude tellurium comprise 70 to 99 percent of Te, 0.1 to 1 percent of Se and the balance of impurities.

In some embodiments, in the step one, the raw materials are fed according to the solid-to-liquid ratio (1:4) - (1: 5).

In some embodiments, in step one, the apparatus containing water is a stirred tank. The solution is strong acid solution, and the stirring kettle can resist strong acid.

In the first step, hydrochloric acid is added to adjust the pH value to be 0.6-2, the strong acidity of the solution is maintained, and the simple substance tellurium can be directly changed into an oxidation state after sodium chlorate is added.

In the first step, the aim of keeping the final pH value at 3-5 is to enable tellurium in the solution to generate water-insoluble tellurium dioxide.

In the first step, the oxidation reaction is stirred for 1-2 hours. In this time frame, the oxidation reaction proceeds relatively completely.

In some embodiments, in the step one, the mass of tellurium to the mass of sodium chlorate is 1:0.3 to 1: 0.54. The amount of sodium chlorate in the range can oxidize tellurium in the raw material and adjust the pH to be finally kept between 3 and 5.

In step one, the reaction principle involved is:

3Te+2ClO₃ ^-＝3TeO₂↓+2Cl^-

te reacts easily to tellurium dioxide in a +4 valence state under an acidic condition, so that the tellurium dioxide is precipitated.

In addition, NaClO₃The reaction principle involved is also:

2NaClO₃+4HCl＝2ClO₂+Cl₂↑+2NaCl+2H₂O

and (5) treating the filtrate generated in the pressure filtration in the step two as waste liquid.

In the third step, sodium hydroxide is added into the tellurium material to adjust the pH value to be more than or equal to 14. And a strong alkaline environment is kept. After the crude tellurium is subjected to oxidation leaching, the tellurium in the leaching slag is mainly TeO₂In the form of Se, SeO₂、SeO₃And the like. The chemical property of tellurium is similar to that of sulfur and selenium, but tellurium is more alkaline than sulfur and selenium, and tellurium dioxide is easily dissolved in a strong alkali solution to generate tellurite.

In step three, the reaction equation involved is:

TeO₂+2OH^-＝TeO₃ ^2-+H₂O

in some embodiments, in step three, sodium hydroxide is added to adjust the pH to 14. Namely, strong alkaline conditions are kept, which is beneficial to tellurium dioxide to generate tellurite.

In the third step, sodium hydroxide is added into the tellurium material and then the mixture is stirred for 2-3 hours. The tellurium dioxide and the sodium hydroxide are not completely reacted when the stirring time is too short; the stirring time is too long, and the recovery period is prolonged.

In some embodiments, in step three, the tellurium material is stirred for 2 hours after adding the sodium hydroxide.

In the third step, the alkaline leaching solution contains a small amount of impurities such as Cu, Pb, Bi and the like, and a proper amount of sodium sulfide is added into the alkaline leached sodium tellurite solution to remove impurities insoluble in alkaline solution and impurities such as Cu, Pb, Bi and the like. In other words, the heavy metals in step three include Cu, Pb, Bi. The reaction equation involved is:

Na₂S+Na₂PbO₂+2H₂O＝PbS↓+4NaOH

Na₂S+Na₂CuO₂+2H₂O＝CuS↓+4NaOH

bismuth ions generate bismuth hydroxide under alkaline conditions, and the bismuth hydroxide is insoluble in alkali, so that heavy metal bismuth can be removed under alkaline conditions.

In some embodiments, in step three, the amount of sodium sulfide solution added reacts until the copper, lead, bismuth content in the solution is less than 2 ppm. The sodium sulfide is used for removing metal impurities in the materials, and complete removal can be considered when the content of copper, lead and bismuth in the solution is less than 2 ppm.

And returning filter residues generated by filter pressing in the third step to the first step for acidic oxidation treatment.

In the fourth step, the reaction principle involved in the electrolysis is as follows:

Na₂TeO₃+H₂O＝Te↓+2NaOH+O₂↑

the anode reaction is as follows: 4OH^-＝2H₂O+O₂↑+4e^-

The cathode reaction is as follows: TeO₃ ^2-+3H₂O+4e＝Te↓+6OH^-

In some embodiments, in step four, the solution for washing tellurium is water. The tellurium is insoluble in water, and the alkaline solution on the surface of the tellurium can be washed clean by water without influencing the purity of the tellurium.

In the fourth step, the standard that the analysis of the impurity removing liquid is qualified is that the content of the impurities of copper, lead and bismuth in the solution is less than 2 ppm.

In the fourth step, the solution is clear and transparent after filter pressing.

In some embodiments, in step one, the drying is performed at a temperature of not higher than 100 ℃. The drying refers to a process of introducing hot air to evaporate and take away water in the materials, and the water on the surface can be dried under the condition of being less than 100 ℃, so that higher temperature is not needed.

In some embodiments, the elemental tellurium after washing and drying in the fifth step is formed by melting and casting. The melting point of the simple substance tellurium is relatively low, and the simple substance tellurium can be melted and cast into a required product according to requirements.

Finally, a test process is given.

Example 1

The method comprises the following steps: acid oxidation: adding 486g of crude tellurium (Te is 81.9 percent and Se is 0.12 percent) material into a stirring kettle filled with water according to the solid-to-liquid ratio of 1:4 to prepare suspension, then adding 22.5g of 31 percent hydrochloric acid into the suspension to adjust the pH value to 1.5, then adding 135g of sodium chlorate into the stirring kettle, heating to 80-85 ℃ for oxidation, stirring for reaction and oxidation for 1 hour, and finally controlling the pH value to be 3-5.

Step two: and (3) filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residue, wherein the mass of the filter residue is 337.5g, and the filter residue is a tellurium material;

step three: and (3) filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues;

step four, electrolyzing impurity removing liquid: and (3) after the impurity removal solution is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain elemental tellurium (the electrolysis mother solution is recycled), wherein the purity of the analyzed tellurium is 99.99%.

Example 2

The method comprises the following steps: acid oxidation: adding 500g of crude tellurium (Te is 78.76% and Se is 0.11%) into a stirring kettle filled with water according to a solid-to-liquid ratio of 1:4 to prepare suspension, adding 25.5g of 31% hydrochloric acid into the suspension to adjust the pH value to 0.6, adding 158g of sodium chlorate into the stirring kettle, heating to 80-85 ℃ for oxidation, stirring for reaction and oxidation for 1h, and finally controlling the pH value to be 3-5.

Step two: and (3) filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residue, wherein the mass of the filter residue is 349g, and the filter residue is a tellurium material;

step three: and (3) filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues;

step four, electrolyzing impurity removing liquid: and (3) after the impurity removal solution is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain elemental tellurium (the electrolysis mother solution is recycled), wherein the purity of the analyzed tellurium is 99.99%.

Example 3

The method comprises the following steps: acid oxidation: adding 260g of crude tellurium (Te is 98.5 percent and Se is 0.28 percent) material into a stirring kettle filled with water according to the solid-to-liquid ratio of 1:4 to prepare suspension, then adding 26.5g of 31 percent hydrochloric acid into the suspension to adjust the pH value to be 1, then adding 137g of sodium chlorate into the stirring kettle, heating to 80-85 ℃ for oxidation, stirring for reaction and oxidation for 1 hour, and finally controlling the pH value to be 3-5.

Step two: and (3) filter pressing: carrying out filter pressing after the oxidation is finished to obtain filtrate and filter residues, wherein the mass of the filter residues is 386g, and the filter residues are tellurium materials;

step three: and (3) filtering residues and removing impurities: adding sodium hydroxide into the tellurium material to adjust the pH value to 14, stirring for 2-3 h, adding a sodium sulfide solution to remove heavy metals except tellurium in the solution, and performing filter pressing to obtain impurity-removed liquid and filter residues;

step four, electrolyzing impurity removing liquid: and (3) after the impurity removal solution is qualified in analysis, performing filter pressing and clearing, transferring the impurity removal filtrate into an electrolytic cell to start electrolysis, and then washing and drying the electrolyzed tellurium to obtain elemental tellurium (the electrolysis mother solution is recycled), wherein the purity of the analyzed tellurium is 99.99%.

The above-disclosed features are not intended to limit the scope of practice of the present disclosure, and therefore, all equivalent variations that are described in the claims of the present disclosure are intended to be included within the scope of the claims of the present disclosure.