Method for removing dithionate ions in manganese sulfate solution

Abstract

The invention provides a method for removing dithionate ions in a manganese sulfate solution, and belongs to the technical field of inorganic salt purification, and the method comprises the following steps: adding a catalyst electrolytic manganese dioxide according to the content of dithionate ions in a manganese sulfate fine filtrate, and supplementing concentrated sulfuric acid until the solution reaches a set concentration; a proper amount of hydrogen peroxide is added after the reaction, the manganese sulfate solution with dithionate ions removed is obtained through filtration after the reaction is performed for a certain time, the treated solution can pass electrolysis verification, and high-quality production of subsequent products is ensured. According to the method provided by the invention, the catalyst can catalytically oxidize the dithionate to generate the sulfate radical under the acidic condition, the catalyst is simple and easy to obtain, other impurities are not introduced in the reaction process, and the removal effect of the dithionate radical and the high quality of subsequent products are ensured.

Description

Technical Field

[0001] The present application belongs to the technical field of inorganic salt purification and relates to a method for removing dithionate ions in a manganese sulfate solution. Background Art

[0002] In the electrolytic manganese industrial production, the sulfur dioxide reduction method has the advantages of fast leaching rate and high manganese extraction rate, and is the main process for producing manganese sulfate using pyrolusite. However, the production process will generate incomplete oxidation products such as manganese dithionate, which is difficult to remove, and it is difficult to separate manganese dithionate from manganese sulfate, resulting in a serious decline in the quality of the manganese sulfate product and an adverse effect on the subsequent production of manganese-based materials, which has become a technical bottleneck and key issue limiting the large-scale application of the sulfur dioxide leaching pyrolusite process.

[0003] In existing reports, there is almost no effective method to completely eliminate dithionate in manganese sulfate solution: dithionate is extremely stable at room temperature and is not easily oxidized, so manganese dithionate cannot be removed by ordinary oxidation methods. The energy consumption required for removing dithionate by solid phase decomposition method is extremely high, and the production cost cannot be supported. In addition, the quality of the products obtained by this method is uneven and cannot be applied in industry. Therefore, there is an urgent need for an economical and efficient method to remove dithionate, a by-product in the sulfur dioxide leaching process of pyrolusite. Summary of the invention

[0004] The present application provides a method for removing dithionate ions in a manganese sulfate solution, which aims to solve the problem that the byproduct dithionate ions in the sulfur dioxide leaching process of pyrolusite cannot be completely eliminated to a certain extent.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for removing dithionate ions in a manganese sulfate solution, comprising the following steps:

[0006] S1. According to the content of dithionate in the manganese sulfate filtrate, a catalyst is added and stirred to obtain a first solution;

[0007] S2, adding concentrated sulfuric acid to the first solution until the solution reaches a set concentration, reacting at a set temperature to obtain a second solution;

[0008] S3, adding excess hydrogen peroxide to the second solution for reaction, and filtering to obtain a manganese sulfate solution from which dithionate ions have been removed.

[0009] The method provided by the present invention removes dithionate ions in the solution after the reaction under the conditions of low acid concentration and low temperature. Compared with the prior art, the present invention has the following beneficial effects: 1. The catalyst can catalytically oxidize dithionate to generate sulfate under acidic conditions, and the catalyst is simple and easy to obtain, with low cost and high efficiency, and other impurities will not be introduced during the reaction, thereby ensuring the removal effect of dithionate and the high quality of subsequent products; 2. When the amount of catalyst electrolytic manganese dioxide is increased, the decomposition rate of dithionate in the solution can be accelerated, the time required for the reaction is shorter, and the energy consumption required for production can be further reduced. DETAILED DESCRIPTION

[0010] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0011] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0012] In the present application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all mean: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, where a, b, c can be single or multiple, respectively.

[0013] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. For example, without departing from the scope of the implementation regulations of this application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0014] The terms used in the embodiments of the present application are only for the purpose of describing specific implementation rules, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the implementation rules of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0015] It should be understood that in the various embodiments of the present application, the size of the serial number of each process does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the implementation regulations of this application.

[0016] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0017] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0018] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0019] A method for removing dithionate ions from a manganese sulfate solution comprises the following steps:

[0020] S1. According to the content of dithionate in the manganese sulfate filtrate, a catalyst is added and stirred to obtain a first solution;

[0021] S2, adding concentrated sulfuric acid to the first solution until the solution reaches a set concentration, reacting at a set temperature to obtain a second solution;

[0022] S3, adding excess hydrogen peroxide to the second solution for reaction, and filtering to obtain a manganese sulfate solution from which dithionate ions have been removed.

[0023] In one embodiment, the manganese sulfate concentrate filtrate is a crude product of the process of removing sulfur dioxide from leaching pyrolusite, specifically: after slurrying the ore powder, desulfurization and manganese extraction are carried out in a multi-stage series countercurrent absorption combined reactor system to obtain a manganese sulfate crude liquid; after the manganese sulfate crude liquid is impurity-removed and filtered, a manganese sulfate concentrate filtrate is obtained.

[0024] In the sulfur dioxide leaching process of pyrolusite, the generation of by-product dithionite can be preliminarily controlled during the first leaching, and the concentration will not be too high. Therefore, during the subsequent removal, the concentration of concentrated sulfuric acid required is lower, the reaction conditions are more gentle, and the requirements for production equipment are lower, which is conducive to further reducing the production cost.

[0025] The manganese sulfate solution is a solution containing dithionate, such as a manganese sulfate solution containing a high concentration of dithionate in which manganese dioxide and sulfur dioxide are combined, a leaching solution of manganese ore and sulfur dioxide, etc. In the present invention, the amount of electrolytic manganese dioxide used as an oxidant has an effect on the decomposition rate of dithionate. When the amount of electrolytic manganese dioxide is increased, it is conducive to the positive reaction and more conducive to the rapid decomposition of dithionate.

[0026] In one embodiment, the catalyst is electrolytic manganese dioxide.

[0027] In one embodiment, the molar mass of the catalyst in step S1 is 2-5 times that of the dithionate.

[0028] The amount of catalyst electrolytic manganese dioxide used in step S1 has a significant effect on the removal rate of dithionate; when the dithionate content is high, the amount of catalyst electrolytic manganese dioxide required for the reaction increases, and a slight excess of electrolytic manganese dioxide is more conducive to the forward reaction and to increasing the removal rate of dithionate.

[0029] In one embodiment, the dithionate content in step S1 is measured by distillation-iodine titration.

[0030] In one embodiment, the set concentration of the solution in step S2 is concentrated sulfuric acid controlled at 5-100 g / L, more preferably 5-20 g / L.

[0031] In one embodiment, the set temperature in step S2 is 80-200° C. If the reaction temperature is too low, the dithionate in the solution cannot be effectively decomposed. If the temperature is too high, the equipment requirements are high and the production cost is too high.

[0032] In one embodiment, when hydrogen peroxide is added to react in step S3, the reaction temperature is ≤70° C. If the temperature is too high, hydrogen peroxide will decompose.

[0033] In one embodiment, when hydrogen peroxide is added in step S2, the reaction time is 2 hours to 10 hours. If the reaction time is too short, the reaction effect cannot be achieved.

[0034] In one embodiment, in the manganese sulfate solution from which dithionate ions are removed in step S3, the concentration of dithionate ions is less than 0.2 g / L.

[0035] In the leaching compound solution containing dithionate, a certain amount of electrolytic manganese dioxide is added, and the concentrated sulfuric acid content is supplemented to an appropriate concentration. Under corresponding temperature conditions, dithionate is decomposed, and then hydrogen peroxide is used for subsequent treatment to obtain a high-purity manganese sulfate solution; the obtained treated solution is further subjected to electrolysis testing, and the voltage during electrolysis is normal, and the obtained product MnO2 content (>92%) and Cu (<0.9) are normal. It is determined that the very small amount of dithionate remaining has no adverse effect on the subsequent electrolysis, and has the advantages of low cost and high removal rate. The solution treated by this method is measured by distillation-iodine titration to obtain a dithionate content in the solution after the reaction that is less than 0.2g / L or less than the detectable range.

[0036] The technical solution of the present application is illustrated below through specific embodiments and comparative examples.

[0037] In order to enable the above implementation details and operations of the present application to be clearly understood by those skilled in the art, as well as to demonstrate the significant improvement in performance of the embodiments of the present application, the above technical solutions are illustrated by means of multiple embodiments below.

[0038] Embodiment 1:

[0039] A method for removing dithionate ions from manganese sulfate solution:

[0040] Obtaining manganese sulfate solution: Manganese dioxide is introduced into sulfur dioxide to produce a solution containing high concentration of dithionate (S2O6 2- ,M=160, the same below) manganese sulfate solution is diluted and added with high purity manganese sulfate to prepare a manganese sulfate concentration of about 300g / L and a dithionate ion concentration of 9g / L.

[0041] S1. Take 500 mL of the prepared solution into a high temperature reaction kettle and add 10 g of catalyst electrolytic manganese dioxide (MnO2, M=87, the same below);

[0042] S2. Add concentrated sulfuric acid to make the concentration of the solution 100g / L; react at 100℃ for 5h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0043] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution using distillation-iodine titration. No dithionate ion is detected in the solution, and the removal rate reaches 100%.

[0044] The solution obtained by multiple reactions was electrolyzed, and the voltage was normal during electrolysis. The MnO2 content (92.63%) and Cu content (0.78 μg / g) of the obtained product were normal. It was proved that the solution treated in this way did not affect the subsequent production, and the next step of production could be carried out to obtain qualified products.

[0045] Embodiment 2:

[0046] A method for removing dithionate ions from manganese sulfate solution:

[0047] The difference between this embodiment and embodiment 1 is that the concentration of sulfuric acid used is different, which is reduced to 50 g / L compared with 100 g / L in embodiment 1, and the effect is the same.

[0048] S1. As in Example 1, 500 mL of the prepared solution was placed in a high temperature reaction kettle, and 10 g of electrolytic manganese dioxide was added;

[0049] S2. Add concentrated sulfuric acid to make the concentration of the solution 50g / L; react at 100℃ for 5h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0050] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration method. No dithionate ion is detected in the solution, and the removal rate reaches 100%. The solution obtained by multiple reactions is electrolyzed. The voltage during electrolysis is normal, and the MnO2 content (92.48%) and Cu content (0.87 μg / g) of the obtained product are normal.

[0051] Embodiment 3:

[0052] A method for removing dithionate ions from manganese sulfate solution:

[0053] The difference between this embodiment and embodiment 1 is that the acid concentration is reduced to 10 g / L and the reaction temperature is increased to 120° C. In this reaction, when the acid concentration is low, the required temperature increases to achieve the removal effect.

[0054] S1. As in Example 1, 500 mL of the prepared solution was placed in a high temperature reaction kettle, and 10 g of electrolytic manganese dioxide was added;

[0055] S2. Add concentrated sulfuric acid to make the concentration of the solution 10g / L; react at 120℃ for 5h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0056] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 0.032 g / L. The solution obtained by multiple reactions is electrolyzed. The voltage during electrolysis is normal. The MnO2 content (92.58%) and Cu content (0.75 μg / g) of the obtained product are both normal.

[0057] Embodiment 4:

[0058] A method for removing dithionate ions from manganese sulfate solution:

[0059] The difference between this embodiment and embodiment 1 is that the concentration is reduced to 5 g / L and the reaction temperature is increased to 150° C., which is the optimization of conditions during the experiment. When the concentration is lower, the equipment requirements are also lower.

[0060] S1. As in Example 1, 500 mL of the prepared solution was placed in a high temperature reaction kettle, and 10 g of electrolytic manganese dioxide was added;

[0061] S2. Add concentrated sulfuric acid to make the concentration of the solution 5g / L; react at 150℃ for 5h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0062] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 0.128 g / L. The solution obtained by multiple reactions is electrolyzed. The voltage during electrolysis is normal. The MnO2 content (92.32%) and Cu content (0.88 μg / g) of the obtained product are both normal.

[0063] Experimental Example 5:

[0064] A method for removing dithionate ions from manganese sulfate solution:

[0065] The difference between this embodiment and embodiment 3 is that the amount of electrolytic manganese dioxide is reduced to 5 g / L, which is the optimization of conditions in this experimental process. When the amount of catalyst is reduced, the reaction time is longer.

[0066] S1. As in Example 3, 500 mL of the prepared solution was placed in a high temperature reaction kettle, and 5 g of electrolytic manganese dioxide was added;

[0067] S2. Add concentrated sulfuric acid to make the concentration of the solution 10g / L; react at 120℃ for 10h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0068] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 0.032 g / L. The solution obtained by multiple reactions is electrolyzed. The voltage during electrolysis is normal. The MnO2 content (92.38%) and Cu content (0.78 μg / g) of the obtained product are both normal.

[0069] Experimental Example 6:

[0070] A method for removing dithionate ions from manganese sulfate solution:

[0071] The difference between this embodiment and embodiment 4 is that the amount of electrolytic manganese dioxide is reduced to 5 g / L, which is the optimization of conditions in this experimental process. When the amount of catalyst is reduced, the reaction time is longer.

[0072] S1. As in Example 4, 500 mL of the prepared solution was placed in a high temperature reaction kettle, and 5 g of electrolytic manganese dioxide was added;

[0073] S2. Add concentrated sulfuric acid to make the concentration of the solution 10g / L; react at 120℃ for 10h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0074] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 0.032 g / L. The solution obtained by multiple reactions is electrolyzed. The voltage during electrolysis is normal. The MnO2 content (92.32%) and Cu content (0.79 μg / g) of the obtained product are both normal.

[0075] Embodiment 7:

[0076] A method for removing dithionate ions from manganese sulfate solution:

[0077] It is confirmed through Examples 4 and 6 that a good dithionate ion removal effect can be achieved under the condition of 5 g / L acid; usually in experiments, the dithionate ion content will be lower than the prepared solution used in Example 1. Therefore, the difference between this embodiment and Example 1 is that the acid concentration is maintained at 5 g / L, and the combined experimental leaching solution is used, and the dithionate ion content is lower, and the amount of electrolytic manganese dioxide is reduced accordingly according to the dithionate content.

[0078] S1. Take a manganese ore and use sulfur dioxide to reduce the leached chemical solution to remove iron and heavy metals. The content of dithionate in the solution is 2.35g / L, and 3g / L of electrolytic manganese dioxide is added;

[0079] S2, add concentrated sulfuric acid to make the concentration of the solution 5g / L, react at 150℃ for 5h, put the solution into a 3L beaker after the reaction, heat it to 60℃ in a water bath and then cool it naturally;

[0080] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 0.064 g / L. The solution obtained by multiple reactions is electrolyzed. The voltage during electrolysis is normal. The MnO2 content (92.52%) and Cu content (0.76 μg / g) of the obtained product are both normal.

[0081] Comparative Example 1:

[0082] A method for removing dithionate ions from manganese sulfate solution:

[0083] The difference between this comparative example and Example 1 is that a chemical solution with a lower content of dithionate ions is used, the amount of electrolytic manganese dioxide is reduced to 1.5 g / L, and the concentration of sulfuric acid is 10 g / L.

[0084] S1. Take a manganese ore and use sulfur dioxide to reduce the leached chemical solution to remove iron and heavy metals. The content of dithionate in the solution is 2.35g / L, and 1.5g / L of electrolytic manganese dioxide is added;

[0085] S2. Add concentrated sulfuric acid to make the concentration of the solution 10g / L; react at 120℃ for 5h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0086] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 1.52 g / L. The solution obtained by multiple reactions is electrolyzed. The electrolysis process is abnormal, and gray-black turbidity appears.

[0087] The chemical solution used in this example has a lower content of dithionate ions, and the sulfuric acid concentration is 10 g / L. When the amount of electrolytic manganese dioxide is reduced to 1.5 g / L, the removal effect does not meet the requirements when the temperature reaches 120°C and the reaction is carried out for 5 hours. This comparative example proves that the catalyst must be excessive in the experiment to increase the reaction rate.

[0088] Comparative Example 2:

[0089] A method for removing dithionate ions from manganese sulfate solution:

[0090] The difference between this comparative example and Example 1 is that a chemical solution with a lower content of dithionate ions is used, the amount of electrolytic manganese dioxide is reduced to 3 g / L, the concentration of sulfuric acid is 10 g / L, and the reaction time is shortened to 3 h.

[0091] S1. As in Comparative Example 1, 500 mL of the compound solution with a lower content of dithionate ions was placed in a high-temperature reaction kettle, and 3 g of electrolytic manganese dioxide was added;

[0092] S2. Add concentrated sulfuric acid to make the concentration of the solution 10g / L; react at 120℃ for 3h. After the reaction, place the solution in a 3L beaker, heat to 60℃ in a water bath and then cool naturally;

[0093] S3. Add 30 mL of 30% hydrogen peroxide solution, stir mechanically for 4 hours, filter, and detect the resulting solution by distillation-iodine titration. The amount of dithionate detected in the solution is 1.12 g / L. The solution obtained by multiple reactions is electrolyzed. The electrolysis process is abnormal, and gray-black turbidity appears.

[0094] The chemical solution used in this example has a lower content of dithionate ions, and the sulfuric acid concentration is 10g / L. When the amount of electrolytic manganese dioxide is reduced to 3g / L, when the temperature reaches 120°C and the reaction time is shortened to 3h, the removal effect does not meet the requirements. This comparative example proves that when the catalyst is appropriate in the experiment, sufficient reaction time is also required to achieve better results.

[0095] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0096] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for removing dithionate ions from a manganese sulfate solution, characterized in that: The following steps are involved: S1. According to the content of dithionate in the manganese sulfate filtrate, a catalyst is added and stirred to obtain a first solution; S2, adding concentrated sulfuric acid to the first solution until the solution reaches a set concentration, reacting at a set temperature to obtain a second solution; S3, adding excess hydrogen peroxide to the second solution for reaction, and filtering to obtain a manganese sulfate solution from which dithionate ions have been removed.

2. The method according to claim 1, characterized in that The manganese sulfate concentrate filtrate is a crude product in the process of removing sulfur dioxide from leaching pyrolusite, specifically: after slurrying the ore powder, desulfurization and manganese extraction are carried out in a multi-stage series countercurrent absorption combined reactor system to obtain a manganese sulfate crude liquid; after the manganese sulfate crude liquid is impurity-removed and filtered, a manganese sulfate concentrate filtrate is obtained.

3. The method according to claim 1, characterized in that The catalyst is electrolytic manganese dioxide.

4. The method according to claim 1, characterized in that: The molar mass of the catalyst in step S1 is 2-5 times that of the dithionate.

5. The method according to claim 1, characterized in that The dithionate content in step S1 is measured by distillation-iodine titration.

6. The method according to claim 1, characterized in that The set concentration of the solution in step S2 is that the concentration of concentrated sulfuric acid is controlled at 5-100 g / L.

7. The method according to claim 1, characterized in that The set temperature in step S2 is 80-200°C.

8. The method according to claim 1, characterized in that When hydrogen peroxide is added to react in step S2, the reaction temperature is ≤70°C.

9. The method according to claim 1, characterized in that: When hydrogen peroxide is added to react in step S2, the reaction time is 2h-10h.

10. The method according to claim 1, characterized in that In the manganese sulfate solution from which dithionate ions are removed in step S3, the concentration of dithionate ions is lower than 0.2 g / L.