Process for removing molybdenum by in-situ reaction and deep adsorption of sodium permanganate based on manganese sulfate solution

Abstract

The invention discloses a manganese sulfate solution-based sodium permanganate in-situ reaction deep adsorption molybdenum removal process, which comprises the following steps of: taking a manganese sulfate solution, and pouring the manganese sulfate solution into a container; the PH value of the solution in the container is adjusted to 3.0-3.5, and the temperature in the container is increased to 60 DEG C or above; sodium permanganate is added into the manganese sulfate solution, manganese sulfate is oxidized by permanganate radicals in the sodium permanganate, chemical manganese dioxide is directly generated in the container, and molybdenum in the container is adsorbed by the chemical manganese dioxide. The method has the beneficial effects that potassium ions are not remained in the solution after the oxidant is added, the problem of overhigh concentration of the potassium ions in the solution can be directly avoided, and when the concentration of the potassium ions in the electrolytic manganese dioxide for preparing the alkaline zinc-manganese battery is overhigh, the corrosion of a zinc negative electrode in the alkaline zinc-manganese battery can be reduced, and the service life of the alkaline zinc-manganese battery is prolonged. The molybdenum removal process has the advantage that the concentration of the residual potassium ions in the manganese sulfate solution is relatively low.

Description

Technical Field

[0001] The invention relates to the technical field of molybdenum removal technology, and in particular to a molybdenum removal technology based on in-situ reaction of manganese sulfate solution and sodium permanganate with deep adsorption. Background Art

[0002] Electrolytic manganese dioxide (EMD) is a key material in the battery industry, used in the production of alkaline zinc-manganese and lithium-manganese batteries. Currently, the production of EMD requires manganese sulfate as a raw material for the electrolytic reaction. The divalent manganese ions in the manganese sulfate are oxidized to tetravalent manganese at the anode, producing EMD at the anode. During the electrolytic deposition process, molybdenum co-crystallizes with the manganese dioxide, forming lattice defects. These defects significantly reduce the electronic conductivity and electrochemical activity of the EMD, leading to a decrease in the battery's discharge capacity and an increase in the self-discharge rate. Especially for mercury-free batteries, the presence of molybdenum accelerates corrosion of the zinc anode, shortening the battery life. Therefore, molybdenum must be removed from the manganese sulfate solution during the EMD production process.

[0003] Chinese invention patent publication CN103570073B discloses a method for deep molybdenum removal from electrolytic manganese dioxide using a manganese sulfate solution. The method comprises the following steps: heating the manganese sulfate solution, adjusting the pH, adding a nascent manganese dioxide suspension, subjecting the solution to microwave radiation, adding a filter aid, and stirring for 30 minutes. The filtrate is then solid-liquid separated to obtain a purified manganese sulfate solution. The microwave radiation is conducted at a power of 400-700W for 10-15 minutes. Using nascent manganese dioxide as the adsorbent, the method significantly improves molybdenum adsorption under microwave radiation, achieving a molybdenum adsorption rate exceeding 99.0%. After molybdenum removal, the molybdenum mass concentration in the manganese sulfate solution is less than 0.003 mg / L, fully meeting the requirements for producing electrolytic manganese dioxide specifically for mercury-free alkaline zinc-manganese batteries.

[0004] In the aforementioned method for deep molybdenum removal from electrolytic manganese dioxide using a manganese sulfate solution, potassium ions remain in the manganese sulfate solution after molybdenum removal. When the potassium ion concentration in the electrolytic manganese dioxide used to prepare alkaline zinc-manganese batteries is too high, this can accelerate corrosion of the zinc negative electrode in the alkaline zinc-manganese battery, leading to a decrease in the battery capacity of the mercury-free alkaline battery. Therefore, existing molybdenum removal processes suffer from the technical problem of excessively high potassium ion concentrations remaining in the manganese sulfate solution. Summary of the Invention

[0005] In order to solve the above technical problems, the object of the present invention is to provide a process for deep molybdenum removal by in-situ adsorption of sodium permanganate in manganese sulfate solution, which comprises the following steps: taking a manganese sulfate solution and pouring the manganese sulfate solution into a container; adjusting the pH value of the solution in the container to 3.0-3.5, and heating the temperature in the container to above 60°C; adding sodium permanganate to the manganese sulfate solution, wherein the permanganate in the sodium permanganate oxidizes the manganese sulfate directly to produce chemical manganese dioxide in the container, and the chemical manganese dioxide adsorbs the molybdenum in the container. The process for deep molybdenum removal by in-situ adsorption of sodium permanganate in manganese sulfate solution has the advantage of a low residual potassium ion concentration.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0007] The process of deep adsorption and molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate includes the following steps:

[0008] S1. Take manganese sulfate solution and pour it into a container;

[0009] S2. Adjust the pH value of the solution in the container to 3.0-3.5 and heat the temperature in the container to above 60°C;

[0010] S3. Sodium permanganate is added to the manganese sulfate solution. The permanganate in the sodium permanganate oxidizes the manganese sulfate to directly generate chemical manganese dioxide in the container. The chemical manganese dioxide adsorbs the molybdenum in the container.

[0011] Preferably, in step S3, the following steps are further included:

[0012] Sodium permanganate was diluted with water before being added to the manganese sulfate solution at a dilution ratio of 1:2.

[0013] Preferably, after step S3, the method further comprises the following steps:

[0014] S4. Stir.

[0015] Preferably, after step S4, the method further comprises the following steps:

[0016] S5, sampling and testing the molybdenum content in the manganese sulfate solution, if the molybdenum content is higher than the target value, proceed to step S3;

[0017] Preferably, in step S5, the following steps are further included:

[0018] If the molybdenum content is lower than the target value, proceed to step S6;

[0019] After step S5, the method further includes the following steps:

[0020] S6. Screen out the chemical manganese dioxide in the manganese sulfate solution.

[0021] Preferably, in step S6, the following steps are further included:

[0022] The manganese sulfate solution was filter-pressed.

[0023] Preferably, in step S5, the following steps are further included:

[0024] The target value is 0.005 ppm.

[0025] Preferably, in step S4, the following steps are further included:

[0026] Stir for 30 minutes.

[0027] Preferably, in step S3, the following steps are further included:

[0028] Add 1 kg of sodium permanganate to every 7 cubic meters of manganese sulfate solution.

[0029] Preferably, in step S3, the following steps are further included:

[0030] The reaction time was 60 minutes.

[0031] Compared with the prior art, the present invention has achieved beneficial technical effects:

[0032] Permanganate is used to directly oxidize the manganese sulfate in the solution into chemical manganese dioxide (CMD). This in-situ generated chemical manganese dioxide is very fine and can form suspended particles of water and manganese dioxide in the solution. Under certain pH conditions, it can also adsorb molybdenum. No potassium ions remain in the solution after the addition of the oxidant, directly avoiding the problem of excessive potassium ion concentration in the solution. When the potassium ion concentration in the electrolytic manganese dioxide used to prepare alkaline zinc-manganese batteries is too high, it can reduce corrosion of the zinc negative electrode in the alkaline zinc-manganese battery, helping to ensure the battery capacity of mercury-free alkaline batteries. This molybdenum removal process has the advantage of a low residual potassium ion concentration in the manganese sulfate solution. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the embodiments, but the scope of protection claimed in the present invention is not limited to the following specific embodiments.

[0034] The process of deep adsorption and molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate includes the following steps:

[0035] S1. Take manganese sulfate solution and pour it into a container.

[0036] S2. Adjust the pH value of the solution in the container to 3.0-3.5 and heat the temperature in the container to 60°C-80°C.

[0037] S3. Add sodium permanganate to the manganese sulfate solution. Add 1 kg of sodium permanganate to every 7 cubic meters of manganese sulfate solution. Dilute the sodium permanganate with water before adding it to the manganese sulfate solution. The dilution ratio is 1:2. The permanganate in the sodium permanganate oxidizes the manganese sulfate to produce chemical manganese dioxide directly in the container. The reaction equation between sodium permanganate and manganese sulfate is:

[0038] 2NaMnO4+3MnSO4+2H2O⇄5MnO2↓+Na2SO4+2H2SO4

[0039] The reaction time is 60 minutes. Chemical manganese dioxide is used to adsorb the molybdenum in the container. After 60 minutes of reaction time, the solution in the container is observed to see whether it is turbid or clear. If it is clear, it indicates that little or no chemical manganese dioxide has been produced. If the solution is turbid, it can be preliminarily determined that chemical manganese dioxide has been produced. Therefore, the turbidity of the solution can be used to determine whether the reaction is proceeding normally and whether chemical manganese dioxide is normally produced in the solution, ensuring that the process can be carried out reliably.

[0040] S4. Stir for 30 minutes.

[0041] S5. Sample the manganese sulfate solution for molybdenum content using a detector or other conventional detection method. If the molybdenum content is higher than a target value, the process proceeds to step S3; if the molybdenum content is lower than the target value, the process proceeds to step S6. The target value is 0.005 ppm.

[0042] S6. Screening out the chemical manganese dioxide in the manganese sulfate solution, and performing filter press on the manganese sulfate solution to filter out the chemical manganese dioxide in the manganese sulfate solution and the molybdenum adsorbed on the chemical manganese dioxide.

[0043] This embodiment has the following advantages:

[0044] Manganese sulfate in solution is directly oxidized using permanganate to form chemical manganese dioxide (CMD). This in-situ generated CMD is very fine and can form a suspension of water and manganese dioxide in solution. Under certain pH conditions, it can also adsorb molybdenum. Sodium permanganate is used as the oxidant to avoid the introduction of potassium ions. Therefore, by carefully controlling the amount of MnO2 generated and the solution pH, keeping the pH near the isoelectric point of CMD, molybdenum removal can be achieved. Furthermore, the addition of the oxidant leaves no potassium ions in the solution, directly avoiding the problem of excessive potassium ion concentrations. When the potassium ion concentration in the electrolytic manganese dioxide used to prepare alkaline zinc-manganese batteries is too high, this can reduce corrosion of the zinc anode in alkaline zinc-manganese batteries, thereby ensuring the battery capacity of mercury-free alkaline batteries. This molybdenum removal process also has the advantage of a low residual potassium ion concentration in the manganese sulfate solution.

[0045] Chemical manganese dioxide is generated in a container filled with manganese sulfate solution, not added externally. The chemical manganese dioxide particles of this original health city are finer and more conducive to the formation of hydrates. In addition, the total surface area of ​​the chemical manganese dioxide particles generated in the container is larger, and the water and hydroxyl groups formed are more abundant, so the adsorption potential is greater, and the adsorption efficiency of molybdenum is higher under the same conditions.

[0046] This process does not require the addition of flocculants, and the sodium permanganate is also in solution. Consequently, the target product, chemical manganese dioxide, is produced in low amounts. Consequently, the amount of residue removed by filter press after molybdenum removal is minimal, significantly reducing the amount of residue to be processed. This is more environmentally friendly and saves time and effort. Therefore, this process simplifies molybdenum removal operations, shortens process time, and improves efficiency.

[0047] By monitoring the molybdenum content in step S5, if the molybdenum content is not lower than the target value, the process proceeds to step S3 again to add sodium permanganate to ensure that there is enough chemical manganese dioxide in the solution to adsorb molybdenum, thereby further ensuring the adsorption effect of molybdenum.

[0048] Sodium permanganate is diluted with water before being added to the manganese sulfate solution so that the sodium permanganate can be mixed more evenly after being added to the manganese sulfate solution, thereby generating chemical manganese dioxide more evenly in the manganese sulfate solution.

[0049] Based on the disclosure and teachings of the above description, those skilled in the art may also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and any modifications and variations of the invention should also fall within the scope of protection of the claims of the present invention. In addition, although certain specific terms are used in this description, these terms are for convenience of description only and do not constitute any limitation to the invention.

Claims

1. A process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate, characterized in that: The following steps are involved: S1. Take manganese sulfate solution and pour it into a container; S2. Adjust the pH value of the solution in the container to 3.0-3.5 and heat the temperature in the container to above 60°C; S3. Sodium permanganate is added to the manganese sulfate solution. The permanganate in the sodium permanganate oxidizes the manganese sulfate to directly generate chemical manganese dioxide in the container. The chemical manganese dioxide adsorbs the molybdenum in the container.

2. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 1, characterized in that: In the step S3, the following steps are also included: Sodium permanganate was diluted with water before being added to the manganese sulfate solution at a dilution ratio of 1:

2.

3. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 1, characterized in that: After step S3, the method further includes the following steps: S4. Stir.

4. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 1, characterized in that: After step S4, the method further includes the following steps: S5. Sampling is performed to detect the molybdenum content in the manganese sulfate solution. If the molybdenum content is higher than the target value, the process proceeds to step S3.

5. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 4, characterized in that: In the step S5, the following steps are also included: If the molybdenum content is lower than the target value, proceed to step S6; After step S5, the method further includes the following steps: S6. Screen out the chemical manganese dioxide in the manganese sulfate solution.

6. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 5, characterized in that: In the step S6, the following steps are also included: The manganese sulfate solution was filter-pressed.

7. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 4, characterized in that: In the step S5, the following steps are also included: The target value is 0.005 ppm.

8. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 3, characterized in that: In the step S4, the following steps are also included: Stir for 30 minutes.

9. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 1, characterized in that: In the step S3, the following steps are also included: Add 1 kg of sodium permanganate to every 7 cubic meters of manganese sulfate solution.

10. The process for deep molybdenum removal based on in-situ reaction of manganese sulfate solution and sodium permanganate according to claim 1, characterized in that: In the step S3, the following steps are also included: The reaction time was 60 minutes.