A process for recycling sodium sulfite solution in copper anode mud hydrometallurgy

Abstract

The present invention discloses a process for recycling sodium sulfite solution in copper anode mud hydrometallurgy, comprising the following steps: Step 1, aeration and chlorine removal: subjecting the tellurium reduction liquid to room temperature aeration treatment, and absorbing the tail gas with a sodium hydroxide solution; Step 2, acidification and aeration: adding the silver reduction liquid to the tellurium reduction liquid after aeration and chlorine removal in small amounts and multiple times, stirring and aerating; Step 3, alkali solution absorption: absorbing the gas generated by the aeration in Step 2 with a sodium hydroxide solution to obtain a sodium sulfite solution for recycling; the silver reduction liquid mainly comprises sodium sulfite, with a pH of 7-9; the tellurium reduction liquid mainly comprises sulfuric acid and chloride ions, with a pH of <1. Beneficial effects: The silver reduction liquid and tellurium reduction liquid generated in the copper anode mud hydrometallurgy process are comprehensively utilized, and sodium sulfite is regenerated from the silver reduction liquid, thereby enabling the sodium sulfite to be recycled to the copper anode mud hydrometallurgy process.

Description

Technical Field

[0001] The invention relates to the technical field of copper anode mud hydrometallurgy, and in particular to a process for recycling sodium sulfite solution in copper anode mud hydrometallurgy. Background Art

[0002] Copper anode slime is a valuable material rich in precious and dispersed metals such as gold, silver, selenium, tellurium, platinum, and palladium. A significant portion of the world's gold and silver production comes from copper anode slime. Over the past decade, with the continuous rise in gold prices, the efficient recovery of precious metals such as gold and silver from copper anode slime, as well as the comprehensive utilization of other valuable metals, has received increasing attention.

[0003] The hydrometallurgical smelting process of copper anode mud extracts a variety of precious metals, such as gold, silver, platinum, and palladium. The production process is generally lengthy, involving numerous chemical reactions, including leaching, reduction, displacement, complexation, neutralization, and precipitation. Sodium sulfite is often used as a reducing or complexing agent to facilitate the separation of different components, and is used in high concentrations and large quantities. Furthermore, in practice, to achieve high reaction yields, the sodium sulfite solution used is often overdosed. After the sodium sulfite leaching reaction, a large amount of sodium sulfite remains in the silver reduction solution. This, when mixed with other components, produces wastewater with high COD levels, typically reaching tens of thousands of milligrams per liter.

[0004] Currently, wastewater containing sodium sulfite is typically treated using methods such as air / oxygen aeration and Fenton oxidation to convert the remaining sodium sulfite into sodium sulfate, or by mixing it into the waste acid treatment system to produce calcium salts. While this can reduce the COD value in the water, the resulting sodium sulfate forms mixed salts with other components and cannot be recycled, increasing the salinity in the wastewater. Therefore, oxidizing excess unreacted sodium sulfite not only increases the difficulty and cost of comprehensive wastewater treatment, but also increases sodium sulfite waste, hindering the recycling of effective resources. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a process for recycling sodium sulfite solution in copper anode mud wet smelting. The process comprehensively utilizes the silver-reduced liquid and tellurium-reduced liquid generated in the copper anode mud wet smelting process, regenerates sodium sulfite from the silver-reduced liquid, and realizes the recycling of sodium sulfite to the copper anode mud wet smelting process.

[0006] The object of the present invention is achieved by the following technical measures: A process for recycling sodium sulfite solution in copper anode mud hydrometallurgy, comprising the following steps:

[0007] Step 1: Aeration and chlorine removal: The tellurium reduction solution is aerated at room temperature, and the tail gas is absorbed with sodium hydroxide solution;

[0008] Step 2, acidification and aeration: add the silver reduction liquid into the tellurium reduction liquid after aeration and chlorine removal in small amounts and multiple times, and stir and aerate;

[0009] Step 3, alkali solution absorption: the gas generated by aeration in step 2 is absorbed by sodium hydroxide solution to obtain sodium sulfite solution, which is reused;

[0010] The main component of the silver reduction solution includes sodium sulfite, pH = 7-9;

[0011] The tellurium reduction solution mainly comprises sulfuric acid and chloride ions, and has a pH value of <1.

[0012] Furthermore, the method further includes tail water treatment, wherein the tail water treatment comprises neutralizing, removing weight, and evaporating the mixed wastewater produced in step 2 with an alkaline solution to obtain waste salt and distilled water, and reusing the distilled water.

[0013] Furthermore, in step 1, the aeration time is 15-40 minutes, and the aeration gas source is air.

[0014] Furthermore, in step 2, when the pH of the mixed wastewater rises to about 3-4, the addition of the silver reduction liquid is stopped, and the aeration gas source is air.

[0015] Furthermore, in step 3, the concentration of the sodium hydroxide solution is 140-170 g / L; the absorption end point is when the pH drops to about 9, and aeration is stopped.

[0016] Furthermore, the alkaline solution used for neutralization in the tail gas treatment is a 1-2% sodium hydroxide solution or alkaline wastewater, and the alkaline wastewater includes one or more of flue gas purification wastewater and acid mist purification wastewater.

[0017] Furthermore, the weight removal in the tail gas treatment adopts electrochemical weight removal or chemical weight removal.

[0018] Furthermore, triple-effect evaporation is used for the evaporation in the tail gas treatment.

[0019] Compared with the prior art, the present invention offers the following advantages: By comprehensively treating the high-concentration sodium sulfite-containing silver reduction liquor and the highly acidic tellurium reduction liquor generated during the copper anode mud hydrometallurgy process, the present invention reduces the COD value of the wastewater generated during the copper anode mud hydrometallurgy process, regenerates and reuses sodium sulfite, increases sodium sulfite utilization, and reduces solid waste. The present invention utilizes the highly acidic tellurium reduction liquor instead of the traditional sulfuric acid to produce sulfur dioxide, thereby utilizing resources and reducing reagent costs. Furthermore, the present invention utilizes alkaline wastewater for neutralization in the tailwater treatment process, further reducing the need for additional reagents and neutralization costs. The present invention simultaneously removes heavy metals by mixing and neutralizing the silver reduction liquor and tellurium reduction liquor, avoiding the need for separate weight removal of multiple wastewaters and saving space. The de-weighted water undergoes triple-effect evaporation, and the distilled water is returned to the process.

[0020] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a process flow chart of sodium sulfite solution recycling.

[0022] Figure 2 It is a process flow chart of the copper anode mud hydrometallurgy process. DETAILED DESCRIPTION

[0023] like Figures 1 to 2 As shown, a process for recycling sodium sulfite solution in copper anode mud hydrometallurgy comprises the following steps:

[0024] Step 1, aeration and chlorine removal: the tellurium reduction liquid is aerated at room temperature to discharge volatile hydrogen chloride gas. The aeration time is 15-40 minutes. The aeration gas source is air, and the tail gas is absorbed by a sodium hydroxide solution with a mass fraction of 1-2%.

[0025] Step 2, acidification and aeration: Add the silver reduction liquid in small amounts and multiple times to the tellurium reduction liquid after aeration and chlorine removal, and stir and aerate to produce sulfur dioxide gas and mixed wastewater until the pH of the mixed wastewater rises to about 3-4. Stop adding the silver reduction liquid. The aeration gas source is air, and the main chemical reaction is SO3 2- +2H + =H2O+SO2.

[0026] Step 3, alkali solution absorption: The gas generated by aeration in step 2 is absorbed by a sodium hydroxide solution with a concentration of 140-170g / L to obtain a sodium sulfite solution. When the pH drops to about 9, the absorption end point is reached and aeration is stopped. The concentration of the obtained sodium sulfite solution can reach 200-250g / L and can be directly returned to the process section for use, such as returning to the sodium sulfite silver separation process. The main chemical reaction that occurs is SO2 + 2OH - =SO3 2- +H2O.

[0027] The silver reduction liquid comprises sodium sulfite and water, wherein the main component thereof comprises sodium sulfite, and the pH value is 7-9. The silver reduction liquid mainly comes from the following process steps: ① separating the copper slag by chlorination to separate the gold to obtain the gold separation liquid and the gold separation slag; ② separating the gold separation slag by sodium sulfite to separate the silver to obtain the silver separation liquid and the silver separation slag; and ③ separating the silver separation liquid to obtain the silver powder and the silver reduction liquid.

[0028] The tellurium reduction liquid includes sulfuric acid, hydrochloric acid and water, as well as trace heavy metal impurity ions. Its main components include sulfuric acid and chloride ions, and the pH is less than 1. The tellurium reduction liquid mainly comes from the following process steps: ① copper slag is chlorinated to separate gold to obtain gold separation liquid and gold separation slag; ② the gold separation liquid is reduced to obtain gold, platinum, palladium, tellurium, etc. and tellurium reduction liquid.

[0029] The process also includes tail water treatment, which involves neutralizing the mixed wastewater produced in step 2 with an alkaline solution, removing weight, and evaporating the mixture to obtain waste salt and distilled water, which is then reused. The alkaline solution used for neutralization in the tail gas treatment is a 1-2% sodium hydroxide solution or alkaline wastewater, which may include one or more of flue gas purification wastewater and acid mist purification wastewater. The tail gas treatment utilizes electrochemical or chemical weight removal for weight removal. The tail gas treatment utilizes triple-effect evaporation for evaporation.

[0030] Example 1

[0031] During the hydrometallurgical smelting process of copper anode mud, the main components of a batch of tellurium reduction solution and silver reduction solution are as follows:

[0032] Tellurium reduction solution: H + (1.82g / L), SO4 2- (52.8 g / L), Cl - (25.4 g / L), heavy metal ions (<1 g / L);

[0033] Silver reduction solution: Na2SO3 (240 g / L), pH = 8;

[0034] Step 1: Take 3L of the tellurium reduction solution and aerate it with room temperature air for 40 minutes to remove volatile HCl gas. Then, absorb the HCl gas with a 1-2% sodium hydroxide solution. The composition of the tellurium reduction solution after aeration is as follows:

[0035] H + (1.60g / L)SO4 2- (52.6g / L), Cl-(17.7g / L), and heavy metal ions (<1g / L).

[0036] Step 2: Add 1.2 L of silver-reduced liquid to the aerated 3 L of tellurium-reduced liquid wastewater in small amounts and multiple times, accompanied by stirring and aeration. When the pH rises to 3, stop adding the silver-reduced liquid.

[0037] Step 3: Absorb the sulfur dioxide gas generated in step 2 with a 160 g / L sodium hydroxide solution. When the pH of the absorption liquid drops to about 9, stop aeration. The absorption liquid at this time is a sodium sulfite solution with a concentration of about 247.2 g / L, which can be directly returned to the section requiring the sodium sulfite solution for use.

[0038] Step 4: After the tellurium reduction solution is mixed with the silver reduction solution and aerated, it is neutralized with flue gas purification wastewater containing approximately 2% sodium hydroxide to a pH of 8. 4 g of a de-heaving agent and 0.2 g of a PAM flocculant are added to remove heavy metals. After filtration, the solution is subjected to triple-effect evaporation to obtain 3 L of evaporated water. This evaporated water can be returned to the process for reuse, and the evaporated mixed salt can be used as reduced solid waste.

[0039] Example 2

[0040] During the hydrometallurgical smelting process of copper anode mud, the main components of a batch of tellurium reduction solution and silver reduction solution are as follows:

[0041] Tellurium reduction solution: H + (1.74g / L), SO4 2- (60.1 g / L), Cl - (23.1 g / L), heavy metal ions (<1 g / L);

[0042] Silver reduction solution: Na2SO3 (225 g / L), pH = 8;

[0043] Step 1: Take 1m 3 The tellurium reduction liquid wastewater is aerated with air at room temperature for 20 minutes to remove the volatile HCl gas, and 1-2% sodium hydroxide solution is used to absorb the HCl gas. The composition of the tellurium reduction liquid after aeration is as follows: + (1.61g / L)SO4 2- (60.2g / L), Cl - (18.5g / L), heavy metal ions (<1g / L).

[0044] Step 2: Transfer 400L of silver reduction liquid to the 1m 3Add the tellurium reduction solution in small amounts and multiple times, accompanied by stirring and aeration. When the pH rises to 4, stop adding the silver reduction solution.

[0045] Step 3: Absorb the sulfur dioxide gas generated in step 2 with a 140 g / L sodium hydroxide solution. When the pH of the absorption liquid drops to about 9, stop aeration. The absorption liquid at this time is a sodium sulfite solution with a concentration of about 213 g / L, which can be directly returned to the section requiring the sodium sulfite solution for use.

[0046] Step 4: After the tellurium reduction solution is mixed with the silver reduction solution and aerated, it is neutralized with flue gas purification wastewater containing about 2% sodium hydroxide to a pH of 8. 1 kg of de-heavy agent and 50 g of PAM flocculant are added to remove heavy metals. After filtration, triple-effect evaporation is performed to obtain 1.1 m 3 The evaporated water can be returned to the process for use, and the evaporated mixed salt can be used as reduced solid waste.

[0047] In the description of the present invention, it should be understood that the terms "upper", "middle", "outer", "inner" and the like indicating directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0048] Those skilled in the art will appreciate that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for recycling sodium sulfite solution in copper anode mud hydrometallurgy, characterized in that: The following steps are involved: Step 1: Aeration and chlorine removal: The tellurium reduction solution is aerated at room temperature, and the tail gas is absorbed with sodium hydroxide solution; Step 2, acidification and aeration: add the silver reduction liquid into the tellurium reduction liquid after aeration and chlorine removal in small amounts and multiple times, and stir and aerate; Step 3, alkali solution absorption: The gas generated by the aeration in step 2 is absorbed by sodium hydroxide solution to obtain a sodium sulfite solution with a sodium sulfite concentration of 200-250g / L, which is directly returned to the sodium sulfite silver separation process; The main component of the silver reduction solution includes sodium sulfite, pH=7-9; The tellurium reduction solution mainly comprises sulfuric acid and chloride ions, and has a pH value of less than 1.

2. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 1, characterized in that: The process also includes tail water treatment, wherein the mixed wastewater produced in step 2 is neutralized with an alkaline solution, subjected to weight removal, and evaporated to obtain waste salt and distilled water, and the distilled water is reused.

3. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 1, characterized in that: The aeration time in step 1 is 15-40 minutes, and the aeration gas source is air.

4. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 1, characterized in that: In step 2, when the pH of the mixed wastewater rises to about 3-4, the addition of the silver reduction solution is stopped, and the aeration gas source is air.

5. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 1, characterized in that: The concentration of the sodium hydroxide solution in step 3 is 140-170 g / L; the absorption end point is when the pH drops to about 9, and aeration is stopped.

6. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 2, characterized in that: The alkaline solution used for neutralization in the tail water treatment is 1-2% sodium hydroxide solution or alkaline wastewater, and the alkaline wastewater includes one or more of flue gas purification wastewater and acid mist purification wastewater.

7. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 2, characterized in that: The weight removal in the tail water treatment is carried out by electrochemical weight removal or chemical weight removal.

8. The process for recycling sodium sulfite solution in copper anode mud hydrometallurgy according to claim 2, characterized in that: The evaporation in the tail water treatment adopts triple-effect evaporation.

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