CN114854992B - Method for separating arsenic and antimony from arsenic caustic sludge leaching solution by deep oxidation - Google Patents

Abstract

The invention discloses a method for deep oxidation and separation of arsenic and antimony from arsenic-alkali residue leachate. The method is to place the arsenic-alkali residue leachate in a reaction vessel; add soluble manganese salt to the arsenic-alkali residue leachate according to a certain As(III)/Mn molar ratio. into the leachate, and stir by blowing oxygen-containing gas into the leachate. After completing the oxidation reaction, filter to obtain oxidized residue and post-oxidation liquid; leave the post-oxidation liquid to stand and then separate to obtain post-antimony precipitated liquid and sodium pyroantimonate. The invention has the advantages of simple operation process, high oxidation efficiency, low cost, and recyclable catalyst, and solves the current problems of high oxidation cost, low efficiency, and difficulty in arsenic and antimony separation of As(III) in arsenic-alkali residue leach solution.

Description

A method for deep oxidation separation of arsenic and antimony from arsenic-alkali residue leaching solution

Technical field

The invention relates to the technical field of hydrometallurgy, and in particular to a method for deep oxidation separation of arsenic and antimony from arsenic-alkali residue leaching solution.

Background technique

Arsenic-alkali residue is a typical by-product of the antimony refining process. It mainly contains 15-20% arsenic, 18-22% antimony and a certain amount of caustic alkali. Arsenic mainly exists in the form of sodium arsenite and sodium arsenate. In addition to antimony existing as sodium antimonite and sodium antimonate, there is also a small amount of metallic antimony. The composition of arsenic-alkali slag is relatively simple and rich in valuable metal antimony. However, due to the similar properties of arsenic and antimony, it is difficult to separate arsenic and antimony. As a result, the disposal of arsenic-alkali slag has always been a thorny issue in the antimony smelting industry. The current mainstream technology for arsenic-alkali residue treatment is the water immersion-oxidation process.

In addition to completing the separation of arsenic and antimony, reducing arsenic toxicity and facilitating arsenic solidification is another purpose of oxidation treatment of arsenic-alkali residue leachate. Therefore, oxidation treatment is one of the necessary steps in the treatment of solutions containing As(Ⅲ). The oxidants reported so far for solutions containing As(Ⅲ) mainly include hydrogen peroxide, chlorine, ozone, potassium permanganate, etc. Among them, hydrogen peroxide is the most commonly used. Excess hydrogen peroxide can act as an effective arsenic oxidant in a wide pH range, especially in alkaline solutions, and can reduce the As(III) concentration in the solution by 10-15 times in a short period of time. There is no doubt that the above-mentioned strong oxidants have high oxidation efficiency for As(Ⅲ) and the oxidation effect of As(III) is very ideal. However, it is an indisputable fact that it consumes a lot and is expensive. At the same time, most oxidants also have the problem of introducing impurities. Therefore, , developing low-cost As(III) oxidation methods is one of the current hot topics in arsenic-containing material processing research.

Air/pure oxygen is undoubtedly the most ideal oxidant, it is cheap and easy to obtain, and does not introduce impurities. It is thermodynamically feasible to oxidize As(III) using air/pure oxygen, but due to kinetic reasons, the oxidation efficiency is low. The oxidation rate of As(III) with oxygen is very slow, and its half-life is as long as about 1 year. Therefore, it has become a consensus among researchers to introduce catalysts into the air/pure oxygen oxidation As(III) reaction system to improve reaction efficiency. For example, patent CN113754040A discloses a method of using micro/nano activated carbon powder to oxidize trivalent arsenic in water. The method is to add micro/nano activated carbon powder to a solution containing trivalent arsenic, and use alkali to adjust the pH of the solution to slightly Alkaline (pH around 7 to 9.5), air/oxygen stirring and reaction for 1 to 3 days can oxidize As(III) in polluted water to As(V). For example, patent CN110204030A discloses a method of using biochar to oxidize trivalent arsenic in groundwater. The method is to add biochar to groundwater containing As(III), and at the same time, oxygen-containing gas is introduced, and the reaction is stirred for 1 to 3 days. As(III) in groundwater can be oxidized to As(V). However, it still takes a long time to completely oxidize As(III) to As(V), and the catalyst cannot be reused. How to further improve the catalytic oxidation rate of As(III) and reuse the catalyst is a key development direction of the industry. .

Contents of the invention

The invention relates to a method for deep oxidation and separation of arsenic and antimony from arsenic and alkali residue leaching solutions, achieving the purpose of deep and efficient oxidation and separation of arsenic and antimony in the arsenic and alkali residue leaching solution and reusing the catalyst.

In order to achieve the above objectives, the present invention proposes a method for deep oxidation separation of arsenic and antimony from arsenic-alkali residue leachate, including the following steps:

Place the arsenic-alkali residue leach solution into the reaction vessel;

Add soluble manganese salt to the leach solution according to a certain As(III)/Mn molar ratio, and bubble oxygen-containing gas into the leach solution for stirring. After completing the oxidation reaction, filter to obtain oxidized slag and oxidized liquid;

The oxidized liquid is allowed to stand and then separated to obtain the antimony precipitated liquid and sodium pyroantimonate.

Preferably, the soluble manganese salt is added in solution.

Preferably, the As(III)/Mn molar ratio is 1.27-50.96:1.

Preferably, the oxygen-containing gas is selected from one of air and industrial pure oxygen, and its flow rate is 0 to 1.2L/min.

Preferably, the temperature inside the reaction vessel is 30 to 90°C.

Preferably, during stirring, the stirring speed is controlled to be 200 to 500 r/min.

Preferably, an aeration strip is installed in the reaction vessel.

Preferably, the oxidation reaction time is controlled to be 1 to 5 hours.

Preferably, the oxidation residue circulation is used to oxidize new arsenic-alkali residue leachate.

Preferably, the resting time of the oxidized liquid is controlled to be 6 to 12 hours.

The technical principles and concepts of the present invention are as follows:

In an open system, As(III) in alkaline solution mainly exists in the form of AsO ₂ ^- ; Mn(II) exists in solid form in alkaline solution, such as Mn(OH) ₂ , MnO ₂ ·nH ₂ O, Mn ₃ O ₄ , MnOOH, MnO _2, etc., pass oxygen-containing gas into the arsenic-alkali residue leaching solution and introduce manganese salt. MnSO ₄ will provide Mn(II) ions. When there are free Mn(II) ions in the solution, The dissolved oxygen will react with it and oxidize it to MnOOH, MnO ₂ , and then directly oxidize it with As(III) in the solution or catalyze the air/pure oxygen oxidation reaction to oxidize As(III) to As(V). The direct oxidation process of As(Ⅲ) by MnO ₂ is divided into two steps: first, As(Ⅲ) is oxidized to As(Ⅴ), usually accompanied by the reduction of Mn(IV) to Mn(III), and then Mn(III) passes through The electron transfer mechanism further reduces to dissolved Mn(II) ions. Therefore, the reactions that may occur inside the system are as shown in the following formulas (1)-(6):

2Μn(II)+Ο ₂ +4OH ^- →2Μn ^IV Ο ₂ +2H ₂ O (1)

4Mn(II)+Ο ₂ +8OH-→4Μn ^III ΟOH+2H ₂ O(2)4Μn ^III ΟOH+Ο ₂ →4Μn ^IV Ο ₂ +2H ₂ O

(3)

2Μn ^IV Ο ₂ +AsO ₂ ^- +2OH ^- →2Μn ^III ΟOH+AsO ₄ ^3- (4)

2Μn ^III ΟOH+AsO ₂ ^- +2H ⁺ →2Mn(II)+AsO ₄ ^3- +2H ₂ O (5)

During the oxidation process of As(III), the oxidation of Sb(III) is also accompanied. After Sb(III) is oxidized to Sb(V), it combines with Na ⁺ and OH ^- in the solution to form NaSb(OH) ₆ precipitate. The chemical reactions involved in this process are shown in the following formulas (7)-(8):

MnO ₂ +Sb(OH) ₃ +4H ₂ O+OH ^- →Sb(OH) ₆ ^- +Mn(OH) ₂ (7)

The catalytic oxidation reaction of As(Ⅲ) and the cyclic regeneration process of MnO ₂ will consume dissolved oxygen. With the continuous blowing of air, the dissolved oxygen in the solution is continuously replenished. Therefore, theoretically, after the MnO ₂ in the solution is recycled and regenerated, the dissolved oxygen in the solution The MnO ₂ content will remain unchanged, providing better direct oxidation and catalytic oxidation performance. After the oxidation reaction, the filtered MnO ₂ can be returned to the oxidation process for reuse.

Compared with the existing technology, the present invention has the following advantages:

(1) The invention is clean and efficient, has low cost, is simple to operate, has low energy consumption, has no special equipment requirements, is convenient for subsequent processing processes, and is easy to realize industrialization.

(2) The technical solution of the present invention adopts a one-step synthesis of manganese-based catalysts in a solution system. The input amount of catalyst raw materials is small, and the oxidant is a cheap and easily available oxygen-containing gas. It can efficiently and completely oxidize As(III) in the leach solution, and realize the removal of arsenic and antimony. Deep separation reduces the concentration of antimony in the solution after antimony precipitation to less than 37 mg/L, ensuring the recovery and utilization of antimony.

(3) The filter residue after completing the oxidation of the leachate in the present invention is MnO ₂ , which has strong recycling performance and can be returned to the oxidation process to continue oxidizing a new portion of the leachate to achieve reusability. Therefore, it is environmentally friendly and does not produce waste gas or waste residue. .

Description of the drawings

Figure 1 is a schematic flow chart of a method for deep oxidation separation of arsenic and antimony from arsenic-alkali residue leaching solution proposed by the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the following examples are based on the technical solution and provide detailed implementation modes and specific operating processes. However, the protection scope of the present invention is not limited to this invention. Example.

Example 1:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, control the As(III)/Mn molar ratio to 1.27:1, 4.25:1, 6.37:1, 12.74:1, 25.48:1 and 50.96:1 respectively, add manganese sulfate monohydrate in solution form, and keep The temperature of the solution is 90°C, then air is blown in, the air flow rate is 1L/min, the stirring speed is 300r/min, stir and oxidize under normal pressure for 2 hours, and the As(III) content of the liquid samples tested is 0mg/L. , 0mg/L, 0mg/L, 0mg/L, 181.4mg/L, 393.1mg/L, the oxidation rates of As(III) to As(Ⅴ) are 100%, 100%, 100%, 100%, respectively. 72.09%, 39.53%.

Example 2:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, add anhydrous manganese chloride in the form of a solution at an As(III)/Mn molar ratio of 25.48:1, keep the solution temperature at 90°C, and then blow in air, the air flow rate is 1L/min, and the stirring speed is 300r/min, stir and oxidize under normal pressure for 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, and 3 hours respectively. The As(III) contents of liquid samples tested were respectively 476.16mg/L, 370.35mg/L, 249.42mg/L, 181.40mg/L, and 0mg/L. The oxidation rate of As(III) to As(Ⅴ) They are 26.74%, 43.02%, 61.63%, 72.09%, 88.37% and 100.00% respectively.

Example 3:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, add manganese nitrate in the form of a solution at an As(III)/Mn molar ratio of 12.74:1, then blow in air, the air flow rate is 1L/min, the stirring speed is 300r/min, stir and oxidize under normal pressure 2 hours, controlling the reaction temperature to 30°C, 45°C, 60°C, 75°C, and 90°C respectively. The As(III) contents of the liquid samples tested were 211.63 mg/L, 181.40 mg/L, 136.05 mg/L, 60.47 mg/L, and 0 mg/L respectively. The oxidation rate of As(III) to As(Ⅴ) They are 67.44%, 72.09%, 79.07%, 90.70% and 100.00% respectively.

Example 4:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, add manganese sulfate in the form of a solution at an As(III)/Mn molar ratio of 12.74:1, keep the solution temperature at 90°C, then blow in air, the stirring speed is 300r/min, stir and oxidize under normal pressure For 2 hours, control the reverse air flow rate to 0L/min, 0.6L/min, 1L/min, and 1.2L/min respectively. The As(III) contents of liquid samples tested were 453.49 mg/L, 90.70 mg/L, 0 mg/L, and 0 mg/L respectively. The oxidation rates of As(III) to As(V) were 30.23% and 86.05 respectively. %, 100%, 100.00%.

Example 5:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, add manganese sulfate in the form of a solution at an As(III)/Mn molar ratio of 12.74:1, keep the solution temperature at 90°C, then blow in air with an air flow rate of 1L/min, stir and oxidize under normal pressure For 2 hours, control the stirring speed to 200r/min, 300r/min, 400r/min, and 500r/min. The As(III) content of the liquid samples tested are 45.35mg/L, 0mg/L, and 15.12mg/L respectively. , 30.23mg/L, the oxidation rates of As(III) to As(Ⅴ) are 93.02%, 100%, 97.67%, and 95.35% respectively.

Example 6:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, add manganese chloride tetrahydrate in the form of a solution at an As(III)/Mn molar ratio of 12.74:1, keep the solution temperature at 90°C, and then blow in air, the air flow rate is 1L/min, and the stirring speed is 300r/min, stir and oxidize under normal pressure for 2 hours, collect the oxidized filter residue, and oxidize a new portion of the leachate, and repeat this cycle 5 times. The As(III) contents of the liquid samples taken from each oxidized solution were 0 mg/L, 0 mg/L, 0 mg/L, 7.63 mg/L, and 20.05 mg/L respectively. As(III) is oxidized to As( The oxidation rates of V) are 100%, 100%, 100%, 98.83%, and 96.92% respectively, indicating that the catalyst has strong recycling performance.

Example 7:

The sample was collected from an antimony smelting plant in my country. The main components of the leachate obtained from leaching different arsenic-alkali residues vary greatly. The initial pH of the solution is 13.4. The main components are as follows:

Take 1.2L of the leaching solution, add anhydrous manganese chloride in the form of a solution at an As(III)/Mn molar ratio of 12.74:1, keep the solution temperature at 90°C, and then blow in air, the air flow rate is 1L/min, and the stirring speed is 300r/min, stir and oxidize under normal pressure for 2 hours, let the oxidized liquid stand still, control the standing time to be 0 hours, 6 hours, and 12 hours respectively. The antimony content of each liquid sample taken for testing is 173.55mg/L. , 117.82mg/L, 36.69mg/L, and the precipitation rates of antimony were 8.66%, 37.99%, and 80.69% respectively, indicating that extending the standing time can effectively deeply separate arsenic and antimony.

For those skilled in the art, various corresponding changes and modifications can be made based on the above technical solutions and concepts, and all these changes and modifications should be included in the protection scope of the claims of the present invention.

Claims (6)

1. The method for separating arsenic and antimony from the arsenic caustic sludge leaching solution by deep oxidation is characterized by comprising the following steps:

placing arsenic caustic sludge leaching liquid into a reaction container;

adding soluble manganese salt into the leaching solution according to a certain As (III)/Mn molar ratio, bubbling oxygen-containing gas into the leaching solution, stirring, and filtering after the oxidation reaction is completed to obtain oxidizing slag and oxidized solution;

standing the oxidized solution, and separating to obtain an antimony-precipitated solution and sodium pyroantimonate;

wherein the soluble manganese salt is added in the form of a solution; the molar ratio of As (III)/Mn is 1.27-50.96:1; the oxygen-containing gas is selected from one of air and industrial pure oxygen, and the flow rate is 0-1.2L/min; the temperature in the reaction vessel is 30-90 ℃.

2. The method for separating arsenic and antimony by deep oxidation from arsenic caustic sludge leaching liquid according to claim 1, wherein the stirring speed is controlled to be 200-500 r/min during stirring.

3. The method for separating arsenic and antimony by deep oxidation from arsenic caustic sludge leaching solution according to claim 1, wherein aeration strips are added in the reaction vessel.

4. The method for deep oxidation separation of arsenic and antimony from arsenic caustic sludge leaching solution according to claim 1, wherein the oxidation reaction time is controlled to be 1-5 h.

5. The method for the deep oxidation separation of arsenic and antimony from arsenic caustic sludge leachate according to claim 1, wherein the oxidation sludge cycle is used for oxidation of new arsenic caustic sludge leachate.

6. The method for separating arsenic and antimony by deep oxidation from arsenic caustic sludge leaching liquid according to claim 1, wherein the standing time of the oxidized liquid is controlled to be 6-12 hours.