Method for oxidizing and separating manganese and magnesium and preparing basic magnesium carbonate by using manganese dioxide as catalyst

Abstract

The invention discloses a method for oxidizing and separating manganese and magnesium and preparing basic magnesium carbonate by using manganese dioxide as a catalyst. The method comprises the following steps: firstly, adding a carbonization precipitator into a solution containing manganese and magnesium to preferentially precipitate and separate out manganese ions, and filtering to obtain manganese carbonate and filtrate A rich in magnesium ions; an oxidizing agent and a catalyst manganese dioxide are added into the filtrate A to catalyze oxygen residual divalent manganese ions and convert the divalent manganese ions into insoluble manganese dioxide, so that efficient separation of manganese and magnesium in the filtrate is realized, the manganese dioxide generated in the oxidation process forms self-enhanced circulation, catalytic activity is continuously provided, the oxidation efficiency is greatly improved, meanwhile, the dosage of the catalyst is reduced, and the cost is reduced. The oxidation reaction rate is stable; adding a carbonization precipitator and alkali into the treated filtrate, and carrying out staged reaction to enable magnesium ions to form high-purity basic magnesium carbonate precipitate. The process provided by the invention realizes efficient selective separation of manganese and magnesium, and the recovered product has high additional value, and can be widely applied to the fields of battery materials, catalysts, flame-retardant materials and the like.

Description

Technical Field

[0001] The invention relates to the technical field of comprehensive utilization of industrial by-products, and in particular to a method for oxidizing and separating manganese and magnesium by using manganese dioxide as a catalyst to prepare basic magnesium carbonate. Background Art

[0002] In the manganese ore smelting process, rhodochrosite, pyrolusite, etc. are usually used as raw materials to produce high-purity manganese-based material products through acid leaching, purification and electrolysis. In the process of acid leaching manganese, the manganese in the ore (Mn² + ) and magnesium (Mg² + ) ions dissolve into the acidic solution at the same time to form a mixed solution containing manganese and magnesium. In addition, smelting solutions, ore acid leaching solutions, mine acid wastewater generated in industrial production processes, and manganese-magnesium wastewater discharged from chemical and battery material production industries are also widely present. The manganese and magnesium ions in these solutions have very similar physical and chemical properties, especially their solubility is close in acidic systems, making it difficult for traditional separation methods to achieve efficient separation of the two, resulting in poor separation effects, low product purity, and failure to achieve efficient recovery and comprehensive utilization of resources.

[0003] Existing technologies such as chemical precipitation, extraction, ion exchange and sulfide precipitation all have limitations. The chemical precipitation method is sensitive to pH and temperature, has poor separation selectivity and is easy to introduce impurities; the extraction method is costly and difficult to recover the solvent; although the ion exchange method has high purity, the equipment investment is large and the process is complex; the sulfide precipitation method is difficult to filter and has high environmental risks. Some processes rely on concentrated crystallization to form complex salts and landfill, which has high processing costs and occupies land resources, and there is a long-term risk of environmental pollution. Therefore, it is urgent to develop an efficient, economical and environmentally friendly separation and recovery process for manganese and magnesium waste liquid, which is suitable for the treatment of smelting by-products, ore acid leaching waste liquid and industrial wastewater, to achieve efficient separation and resource utilization of manganese and magnesium, produce high value-added products, and meet the needs of sustainable development. Summary of the invention

[0004] In view of the technical problem that it is difficult to selectively separate manganese and magnesium in the prior art, the present invention provides a method for oxidatively separating manganese and magnesium using manganese dioxide as a catalyst and preparing basic magnesium carbonate. Through a three-step process (manganese precipitation - catalytic oxidation to remove manganese - magnesium precipitation), efficient separation is achieved by utilizing the solubility difference and redox characteristics of manganese and magnesium ions. The recovered products exist in a high-purity form and can be used to prepare high-value-added manganese carbonate, manganese dioxide and basic magnesium carbonate products respectively. The process flow is simple and can significantly reduce waste liquid discharge and treatment costs.

[0005] The technical solution adopted by the present invention is as follows: A method for oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst to prepare basic magnesium carbonate comprises the following steps: S1. adding alkali to the manganese-magnesium solution, adjusting the pH to 5.5-7.5, and adding a soluble carbonate as a carbonization precipitant to carry out a magnesium ion carbonization precipitation reaction, the reaction temperature is 20-50° C., the reaction time is 0.5-2h, and filtering to obtain manganese carbonate and filtrate A; S2. Adding a catalyst and an oxidant to the filtrate A obtained in step S1 to carry out a catalytic oxidation reaction, the reaction temperature is 10-40°C, the reaction time is 0.5-6h, and filtering to obtain manganese dioxide (including the added catalyst and manganese dioxide generated during the reaction) and filtrate B; S3. Add a soluble carbonate as a carbonization precipitant to the filtrate B obtained in step S2, and add an alkali to adjust the pH of the solution to 8.5-10.5, and react in two stages, the first stage is a magnesium ion carbonization precipitation reaction at a temperature of 20-55°C and a time of 1-4 h, and the second stage is a magnesium carbonate conversion to basic magnesium carbonate at a temperature of 60-95°C and a time of 2-8 h, and filter to obtain a filter residue and a filtrate C; S4. Wash and dry the filter residue obtained in step S3 to obtain basic magnesium carbonate.

[0006] In order to achieve efficient separation of manganese and magnesium in the solution, the present invention proposes a three-step treatment scheme of manganese precipitation - catalytic oxidation to remove manganese - magnesium precipitation. A soluble carbonate is added to the manganese-magnesium solution as a carbonization precipitant. The solubility product of manganese carbonate is smaller than that of magnesium carbonate under the condition of pH 5.5-7.5, so that manganese ions are preferentially precipitated in the form of manganese carbonate, thereby obtaining high-purity manganese carbonate solid and filtrate A rich in magnesium ions. Secondly, in order to further reduce the residual manganese ion concentration in the filtrate A, a catalyst manganese dioxide and an oxidant are added to remove divalent manganese (Mn 2+ ) is oxidized to high-valent manganese (Mn 4+ ), and precipitated in the form of insoluble manganese oxides. After solid-liquid separation, a filtrate B with extremely low manganese content and rich in magnesium ions is obtained. A soluble carbonate is added to the filtrate B as a carbonization precipitant, and an alkali is added to adjust the solution pH to 8.5-10.5, and the magnesium ions are prompted to generate high-purity basic magnesium carbonate precipitation through staged reactions. Through this three-step process, efficient separation and resource recovery of manganese and magnesium are achieved, the process operation is simple, the separation efficiency is high, and it is suitable for the separation and treatment of manganese and magnesium in complex systems.

[0007] Furthermore, in step S1, the manganese-magnesium solution is an industrial waste liquid, a by-product of a smelting process, an acidic mine wastewater, or a treatment liquid of other manganese-magnesium mixtures, especially a sulfate-type waste liquid generated in a smelting process, a manganese- and magnesium-containing waste acid liquid remaining in a metal smelting process, or a manganese- and magnesium-containing mixed waste liquid after acid leaching of an ore.

[0008] Furthermore, in steps S1 and S3, the alkali is one or more of sodium hydroxide, potassium hydroxide, and ammonia water, and the concentration is 0.25-2 mol / L.

[0009] Further, in step S1, the carbonization precipitant is one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate, the concentration of the carbonization precipitant is 0.25-2 mol / L, and the added amount is a molar ratio of the carbonization precipitant to the manganese ions in the solution greater than or equal to 0.8, preferably 0.8-1.5:1.

[0010] In step S1, the chemical reaction equation of the magnesium ion carbonization precipitation reaction is as follows: , .

[0011] In step S1, the concentration of the carbonized precipitant should not exceed 2 mol / L. Too high a concentration will cause the manganese carbonate crystals to grow too fast, forming larger crystals, which may encapsulate a small amount of magnesium ions and cause magnesium loss. If the amount of carbonized precipitant added is too little, the manganese ion concentration in the filtrate is too high, and the amount of oxidant used in the subsequent catalytic oxidation manganese removal step will increase significantly; if added in excess, the pH value of the solution will increase, which is difficult to control in the range of 5.5-7.5, so that both manganese ions and magnesium ions are precipitated in the form of carbonates, affecting the separation efficiency.

[0012] Furthermore, in step S2, the dosage of the catalyst manganese dioxide is 5-200 mg / L filtrate A (5-200 mg manganese dioxide is added per liter of filtrate A).

[0013] It is worth noting that the catalyst here directly determines the final result of catalytic oxidation. Even if manganese trioxide with similar properties is used, although a certain catalytic effect can be achieved, the catalytic effect is far less than that of manganese dioxide.

[0014] The key reason why manganese dioxide is used as a catalyst to oxidize the manganese ions in the solution is that the direct use of peroxide oxidants cannot effectively oxidize Mn 2+ Although Mn 2+ The redox potential of / MnO2 is 1.69 V, and the redox potential of peroxide oxidant is about 1.77 V. In theory, both have the conditions for redox reaction to occur. However, due to the extremely slow reaction kinetics, low electron transfer rate, and high reaction activation energy, the actual reaction almost does not occur. In addition, peroxide oxidant cannot directly generate highly reactive oxygen species (such as hydroxyl radical •OH or superoxide radical O2• - ), and these active species are highly efficient in oxidizing Mn 2+ The core.

[0015] Manganese dioxide is introduced as a catalyst, which can effectively increase the Mn 2+ Oxidation rate. At the same time, the catalyst dosage can be maintained at a low concentration. The manganese dioxide generated during the reaction has catalytic activity itself and can partially replace the initial catalyst, further increasing the catalytic surface area and active sites, thereby maintaining the high oxidation efficiency of the system. As the reaction proceeds, the precipitation of manganese dioxide continues to form, enhancing the ability to decompose peroxides and generate highly reactive oxygen species (ROS), forming a self-enhanced cycle mechanism. Even if the initial catalyst dosage is low, this cycle mechanism can ensure that the oxidation reaction maintains high efficiency and high rate in the later stage, significantly improving the overall performance of the oxidation treatment.

[0016] Furthermore, in step S2, the oxidant is at least one of magnesium peroxide, sodium peroxide, potassium peroxide, urea peroxide, sodium percarbonate, potassium percarbonate, hydrogen peroxide, and potassium persulfate; and the molar ratio of the oxidant to the manganese ions in the filtrate A is greater than or equal to 1, preferably 1-1.5:1.

[0017] In step S2, the chemical reaction equation of the catalytic oxidation reaction is as follows: Peroxides decompose in aqueous solution (taking metal peroxides as an example), where M represents a cation, such as Na + , Ca 2+ Mg 2+ Etc., the reaction formula is as follows: , In this catalytic reaction, the active sites on the surface of MnO2 can cleave H2O2 to generate peroxy radicals (HO2·) and hydroxyl radicals (·OH). The reaction equation is as follows: , The peroxyl radical (HO2·) further reacts to generate superoxide anion radical O2 - ·), the reaction formula is as follows: , Hydroxyl radicals have strong oxidizing properties and can convert Mn 2+ Oxidation to generate Mn 3+ , the reaction formula is as follows: , In aqueous solution, Mn 3+ It is easy to undergo hydrolysis reaction to form hydroxyl compounds. In this reaction system, MnO(OH) is easily oxidized and converted into MnO2. The reaction formula is as follows: , .

[0018] Further, in step S3, the carbonization precipitant is one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate, and the molar ratio of the carbonization precipitant to the magnesium sulfate in the filtrate B is 2-2.5:1.

[0019] Furthermore, in steps S1 and S3, the carbonization precipitant is added in the form of a solid directly or in the form of a solution. In step S1, the solution is preferably added, and in step S3, the solid is preferably added directly.

[0020] In step S3, the first stage is the magnesium ion carbonization precipitation reaction, and the chemical reaction equation is as follows: , , The second stage is the conversion of magnesium carbonate into basic magnesium carbonate. The chemical reaction equation is as follows: .

[0021] The amount of the carbonized precipitant added in step S3 is slightly greater than the theoretical demand for magnesium sulfate to ensure that the magnesium ions are completely precipitated. During the first stage reaction, alkali is continuously consumed during the precipitation of magnesium carbonate, resulting in a decrease in pH. To accelerate the precipitation of magnesium ions, it is necessary to maintain the pH between 8.5 and 10.5 by addition and subtraction.

[0022] The reaction time during the first stage reaction is 1-4 hours. Considering the processing efficiency, the end of the first stage reaction is characterized by the pH of the filtrate B no longer decreasing, which determines whether the reaction is completed.

[0023] The second stage reaction is the process of converting magnesium carbonate into basic magnesium carbonate. The formation temperature of basic magnesium carbonate is above 60°C. However, the carbonization precipitant will decompose above 60°C. Directly raising the temperature to prepare basic magnesium carbonate will lead to a decrease in the precipitation efficiency of magnesium ions. Therefore, a two-stage reaction is adopted. First, magnesium ions are precipitated into magnesium carbonate, and then the magnesium carbonate is converted into basic magnesium carbonate by increasing the temperature. In order to accelerate the formation of basic magnesium carbonate, the second stage reaction temperature is preferably 60-95°C.

[0024] Compared with the prior art, the beneficial effects of the present invention are: The present invention fully combines the solubility difference and redox property of the two through a three-step process of manganese precipitation-catalytic oxidation to remove manganese-magnesium precipitation, and realizes efficient separation and resource utilization of manganese and magnesium. The present invention adopts the oxidation and manganese removal step with manganese dioxide as a catalyst, which can efficiently oxidize the residual divalent manganese into insoluble manganese dioxide, effectively remove manganese ions in the solution, and create conditions for the subsequent high-purity recovery of magnesium ions. Manganese dioxide is generated during the oxidation process to form a self-enhanced catalytic cycle, greatly improve the oxidation efficiency, and reduce the amount of catalyst used, reflecting the dual advantages of high efficiency and economy. The recovered manganese and magnesium exist in the form of high-purity manganese carbonate, manganese dioxide, and basic magnesium carbonate, which are all high value-added products and have wide application value in the fields of lithium ion batteries, catalysts, flame retardant materials, etc.

[0025] In addition, the process flow of the present invention is simple and easy to operate, which reduces the discharge of waste liquid and solid residue, and reduces environmental pollution and treatment costs. The present invention not only realizes efficient separation and recovery of resources, but also takes into account both economic and environmental protection. It is applicable to a variety of complex systems such as smelting waste liquid, ore acid leaching waste water and industrial manganese-magnesium-containing waste liquid, and has significant industrial application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully below in conjunction with the accompanying drawings and preferred embodiments of the specification, but the protection scope of the present invention is not limited to the following specific embodiments.

[0028] 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 in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0030] The composition of the manganese-magnesium solution involved in the following examples is shown in Table 1.

[0031] Table 1 Elemental analysis and results of manganese and magnesium solutions Example 1

[0032] A method for oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst to prepare basic magnesium carbonate, the process flow chart is as follows: Figure 1 As shown, the following steps are included: (1) Take 300 mL of manganese-magnesium solution and adjust the pH to 6.5; weigh 2.72 g of ammonium bicarbonate, dissolve it in water, prepare 50 mL of ammonium bicarbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 20 ° C for 2 h, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0033] (2) The pH value of filtrate A was adjusted to 7.0, 0.267 g of magnesium peroxide and 0.015 g of manganese dioxide were weighed, and quickly added to filtrate A. The magnetic stirring was turned on to ensure that the reaction system was fully mixed. Then, the mixture was placed in a constant temperature water bath, the temperature was controlled to 20°C, and the reaction was maintained for 0.5 hours. After the reaction was completed, the reaction mixture was filtered to obtain black solid manganese dioxide and filtrate B.

[0034] (3) Adjust the pH value of filtrate B to 9.0, weigh 6.61 g of ammonium bicarbonate, and add it to the continuously stirred filtrate B. Place the reaction system in a 40°C constant temperature water bath and continue the reaction for 2 h. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 80°C and continue the reaction for 4 h. After the reaction is completed, solid-liquid separation is performed by suction filtration to obtain white basic magnesium carbonate solid and filtrate C. Example 2

[0035] (1) Take 500 mL of manganese-containing solution and adjust the pH to 7.1; weigh 3.63 g of ammonium bicarbonate, dissolve it in water, prepare 50 mL of ammonium bicarbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 40 °C and react for 2 h. After the reaction, filter the solution to obtain manganese carbonate and filtrate A.

[0036] (2) The pH value of filtrate A was adjusted to 7.2, 0.708 g of urea peroxide and 0.045 g of manganese dioxide were weighed and quickly added to filtrate A, and magnetic stirring was turned on to ensure that the reaction system was fully mixed. Then, the mixture was placed in a constant temperature water bath, the temperature was controlled to 35°C, and the reaction was maintained for 1 h. After the reaction was completed, the reaction mixture was filtered to obtain black solid manganese dioxide and filtrate B.

[0037] (3) Adjust the pH value of filtrate B to 9.0, weigh 11.02 g of ammonium bicarbonate, and add it to the continuously stirred filtrate B. Place the reaction system at 50°C for 2 h. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 75°C and continue the reaction for 4 h. After the reaction is completed, separate the solid and liquid by suction filtration to obtain white basic magnesium carbonate solid and filtrate C. Example 3

[0038] (1) Take 1L of manganese-magnesium solution and adjust the pH to 6.3; weigh 7.27g of ammonium bicarbonate, dissolve it in water, prepare 70mL of ammonium bicarbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 50℃, react for 2 hours, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0039] (2) Adjust the pH value of filtrate A to 7.4, weigh 2.22 g of sodium percarbonate and 0.09 g of manganese dioxide, quickly add them to filtrate A, and turn on the magnetic stirring to ensure that the reaction system is fully mixed. Then place it in a constant temperature water bath, control the temperature to 20°C, and maintain the reaction for 0.5 h. After the reaction is completed, filter the reaction mixture to obtain black solid manganese dioxide and filtrate B.

[0040] (3) Adjust the pH value of filtrate B to 9.0, weigh 22.05 g of ammonium bicarbonate, and add it to the continuously stirred filtrate B. Place the reaction system in a 45°C constant temperature water bath and continue the reaction for 2 hours. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 90°C and continue the reaction for 4 hours. After the reaction is completed, solid-liquid separation is performed by suction filtration to obtain white basic magnesium carbonate solid and filtrate C. Example 4

[0041] (1) Take 1L of manganese-containing magnesium solution and adjust the pH to 7.3; weigh 12.43g of sodium carbonate, dissolve it in water, prepare 70mL of sodium carbonate solution, transfer it into the manganese-containing solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 50℃, react for 2 hours, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0042] (2) Adjust the pH value of filtrate A to 7.0, weigh 0.89 g of magnesium peroxide and 0.05 g of manganese dioxide, quickly add them to filtrate A, and turn on magnetic stirring to ensure that the reaction system is fully mixed. Then place it in a constant temperature water bath to control the temperature to 20°C and maintain the reaction for 0.5 hours. After the reaction is completed, filter the reaction mixture to obtain black solid manganese dioxide and filtrate B.

[0043] (3) Adjust the pH value of filtrate B to 9.0, weigh 22.2 g of sodium carbonate, and add it to the continuously stirred filtrate B. Place the reaction system in a 40°C constant temperature water bath and continue the reaction for 2 h. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 80°C and continue the reaction for 4 h. After the reaction is completed, separate the solid and liquid by suction filtration to obtain white basic magnesium carbonate solid and filtrate C. Example 5

[0044] (1) Take 1L of manganese-magnesium solution and adjust the pH to 6.7; weigh 15.11g of ammonium carbonate, dissolve it in water, prepare 70mL of ammonium carbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 50℃, react for 2 hours, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0045] (2) Adjust the pH value of filtrate A to 3.0, weigh 2.25 g potassium percarbonate and 0.09 g manganese dioxide and quickly add them to filtrate A, and turn on the magnetic stirring to ensure that the reaction system is fully mixed. Then place it in a constant temperature water bath to control the temperature to 20°C and maintain the reaction for 0.5 h. After the reaction is completed, filter the reaction mixture to obtain black solid manganese dioxide and filtrate B.

[0046] (3) Adjust the pH value of filtrate B to 9.0, weigh 19.25 g of ammonium carbonate, and add it to the continuously stirred filtrate B. Place the reaction system in a 45 °C constant temperature water bath and continue the reaction for 2 hours. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 90 °C and continue the reaction for 4 hours. After the reaction is completed, solid-liquid separation is performed by suction filtration to obtain white basic magnesium carbonate solid and filtrate C.

[0047] Comparative Example 1 (1) Take 300 mL of manganese-containing solution and adjust the pH to 6.3; weigh 3.63 g of ammonium bicarbonate, dissolve it in water, prepare 100 mL of ammonium bicarbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 50°C, react for 2 h, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0048] (2) The pH value of filtrate A was adjusted to 7.0, 0.267 g of magnesium peroxide was weighed and quickly added to filtrate A, and magnetic stirring was turned on to ensure that the reaction system was fully mixed. Then, the mixture was placed in a constant temperature water bath to control the temperature to 20°C and the reaction was maintained for 0.5 hours. After the reaction was completed, the reaction mixture was filtered to obtain no black solid manganese dioxide. The filtrate was filtrate B.

[0049] (3) Adjust the pH value of filtrate B to 9.0, weigh 6.61g of ammonium bicarbonate, and add it to the continuously stirred filtrate B. Place the reaction system in a 40℃ constant temperature water bath and continue the reaction for 2 hours. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 80℃ and continue the reaction for 4 hours. After the reaction is completed, solid-liquid separation is performed by suction filtration to obtain yellow basic magnesium carbonate solid and filtrate C.

[0050] Comparative Example 2 (1) Take 500 mL of manganese-containing solution and adjust the pH to 7.1; weigh 5.44 g of ammonium bicarbonate, dissolve it in water, prepare 50 mL of ammonium bicarbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 40 ° C, react for 2 h, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0051] (2) The pH value of filtrate A was adjusted to 7.2, 0.708 g of urea peroxide was weighed and quickly added to filtrate A, and magnetic stirring was turned on to ensure that the reaction system was fully mixed. Then, the mixture was placed in a constant temperature water bath to control the temperature to 35°C and maintained for 1 h. After the reaction was completed, the reaction mixture was filtered, and no black solid manganese dioxide was obtained. The filtrate was filtrate B.

[0052] (3) Adjust the pH value of filtrate B to 9.0, weigh 11.02 g of ammonium bicarbonate, and add it to the continuously stirred filtrate B. Place the reaction system at 50°C and continue the reaction for 2 h. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 75°C and continue the reaction for 4 h. After the reaction is completed, perform solid-liquid separation by suction filtration to obtain white basic magnesium carbonate solid and filtrate C.

[0053] Comparative Example 3 (1) Take 1L of manganese-containing solution and adjust the pH to 6.3; weigh 7.27g of ammonium bicarbonate, dissolve it in water, prepare 70mLg of ammonium bicarbonate solution, transfer it into the manganese-magnesium solution, turn on magnetic stirring to ensure that the reaction system is fully mixed. Control the temperature to 50℃, react for 2 hours, and filter the solution after the reaction to obtain manganese carbonate and filtrate A.

[0054] (2) Adjust the pH value of filtrate A to 3.0, weigh 2.22 g of sodium percarbonate, quickly add it to filtrate A, and turn on magnetic stirring to ensure that the reaction system is fully mixed. Then place it in a constant temperature water bath to control the temperature to 20 °C and maintain the reaction for 0.5 h. After the reaction is completed, the reaction mixture is filtered, and no black solid manganese dioxide is obtained. The filtrate is filtrate B.

[0055] (3) Adjust the pH value of filtrate B to 9.0, weigh 22.05 g of ammonium bicarbonate, and add it to the continuously stirred filtrate B. Place the reaction system in a 45 °C constant temperature water bath and continue the reaction for 2 h. During this period, the pH value of the reaction system solution needs to be monitored, and ammonia water is added in time according to the measurement results to maintain the pH value of the system stable at 9.0 until the pH no longer changes. Raise the reaction temperature to 90 °C and continue the reaction for 4 h. After the reaction is completed, solid-liquid separation is performed by suction filtration to obtain yellow basic magnesium carbonate solid and filtrate C.

[0056] The data results of the embodiments and comparative examples are shown in Table 2.

[0057] Table 2 Data results of examples and comparative examples

[0058]

[0059] According to the data in Table 2, under the conditions of using manganese dioxide as catalyst and peroxide as oxidant in Examples 1 to 5, the manganese ions (Mn² +) The residual amount is significantly lower than that of Comparative Examples 1 to 3. This indicates that manganese dioxide as a catalyst can effectively remove manganese ions and achieve efficient separation of manganese and magnesium. In contrast, under the condition that manganese dioxide is not introduced as a catalyst, the peroxide used as an oxidant in the comparative experiment fails to play the expected effect, resulting in incomplete separation of manganese and magnesium, and a high content of manganese ions in the filtrate B, thereby affecting the purity and quality of the final product.

[0060] The manganese and magnesium recovery data results of the embodiments and comparative examples are shown in Table 3.

[0061] Table 3 Manganese and magnesium recovery data results of the examples and comparative examples

[0062]

[0063] Table 3 further shows the difference between the embodiment and the comparative example experiment in terms of manganese and magnesium recovery rate. The manganese recovery rate of embodiments 1 to 5 is maintained at more than 97%, and the magnesium recovery rate is also more than 94%. Some experiments even reach a high recovery rate close to 99%, while the manganese recovery rate of comparative examples 1 to 3 is only between 86.5% and 87.5%, and the comparative example experiment fails to effectively separate manganese and magnesium, resulting in a lack of magnesium recovery and an impure product. It shows that the method of the embodiment of the present invention not only performs well in the recovery of manganese, but also ensures the efficient recovery of magnesium, and realizes a high-purity basic magnesium carbonate product.

[0064] The traditional carbonization precipitation method has the problems of incomplete separation, serious magnesium loss and low resource utilization in the process of separating manganese and magnesium. The present invention has made significant improvements on this basis, and combined with the physicochemical properties of manganese and magnesium ions, a technical solution for efficient separation and resource recovery is proposed. Through the carbonization precipitation step, the difference in the solubility product of manganese and magnesium is utilized to make most of the manganese ions preferentially precipitate in the form of manganese carbonate, while the magnesium ions are retained in the solution, thereby achieving the preliminary separation of manganese and magnesium. This process not only effectively removes most of the manganese ions, but also reduces the consumption of oxidants in subsequent oxidation treatments. Subsequently, in the oxidation separation stage, a manganese dioxide catalyst and a peroxide oxidant are introduced, and the residual manganese ions are oxidized to high-valent manganese oxides by catalytic oxidation and separated by precipitation in an insoluble form, further improving the selectivity and efficiency of manganese and magnesium separation. Finally, the process of the present invention realizes the efficient separation of manganese and magnesium resources, and converts them into high-value-added industrial products, including manganese carbonate, manganese dioxide and basic magnesium carbonate, fully realizing the comprehensive utilization of resources and maximizing value enhancement.

[0065] The process of the present invention is simple and efficient, suitable for a variety of complex solution systems containing manganese and magnesium, and has broad industrial application potential. It can be used for the separation and resource recovery of manganese and magnesium in complex systems such as smelting waste liquid, mine acidic wastewater, chemical discharge waste liquid, and battery recycling waste liquid. In addition, the process has important application value in environmental governance (such as treatment of heavy metal wastewater containing manganese and magnesium), preparation of high value-added materials, and other industrial processes containing manganese and magnesium. Compared with traditional methods, the present invention not only significantly improves the separation efficiency of manganese and magnesium, reduces production costs and environmental burdens, reduces the discharge of waste liquid and solid residues, and realizes green recovery and recycling of resources. The process fully meets the dual requirements of modern industry for environmental protection and economic benefits, and has significant economic value and promotion potential.

Claims

1. A method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst, characterized in that: The steps include: S1. adding alkali to the manganese-magnesium solution, adjusting the pH to 5.5-7.5, and adding a soluble carbonate as a carbonization precipitant to carry out a magnesium ion carbonization precipitation reaction, the reaction temperature is 20-50° C., the reaction time is 0.5-2h, and filtering to obtain manganese carbonate and filtrate A; S2. Add manganese dioxide as a catalyst to the filtrate A obtained in step S1, and add an oxidant to carry out a catalytic oxidation reaction, the reaction temperature is 10-40°C, the reaction time is 0.5-6h, and the manganese dioxide and the filtrate B are obtained by filtering; S3. Add a soluble carbonate as a carbonization precipitant to the filtrate B obtained in step S2, and add an alkali to adjust the pH of the solution to 8.5-10.5, and react in two stages, the first stage is a magnesium ion carbonization precipitation reaction at a temperature of 20-55° C. for 1-4 hours, and the second stage is a magnesium carbonate conversion to basic magnesium carbonate at a temperature of 60-95° C. for 2-8 hours, and filter to obtain a filter residue and a filtrate C; S4. Wash and dry the filter residue obtained in step S3 to obtain basic magnesium carbonate.

2. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In step S1, the manganese-magnesium solution is a sulfate waste liquid generated during the smelting process, a manganese- and magnesium-containing waste acid liquid remaining in the metal smelting process, or a manganese- and magnesium-containing mixed waste liquid after acid leaching of ore.

3. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In steps S1 and S3, the alkali is one or more of sodium hydroxide, potassium hydroxide, and ammonia water, and the alkali concentration is 0.25-2 mol / L.

4. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In step S1, the carbonization precipitant is one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate, the concentration of the carbonization precipitant is 0.25-2 mol / L, and the molar ratio of the carbonization precipitant to the manganese ions in the solution is 0.8-1.5:

1.

5. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In step S2, the dosage of the catalyst manganese dioxide is 5-200 mg / L filtrate A.

6. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In step S2, the oxidant is at least one of magnesium peroxide, sodium peroxide, potassium peroxide, urea peroxide, sodium percarbonate, potassium percarbonate, hydrogen peroxide, and potassium persulfate.

7. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In step S2, the molar ratio of the oxidant to the manganese ions in the filtrate A is 1-1.5:

1.

8. The method for preparing basic magnesium carbonate by oxidizing and separating manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In step S3, the carbonization precipitant is one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, ammonium bicarbonate, and ammonium carbonate, and the molar ratio of the carbonization precipitant to the magnesium sulfate in the filtrate B is 2-2.5:

1.

9. The method for preparing basic magnesium carbonate by oxidative separation of manganese and magnesium using manganese dioxide as a catalyst according to claim 1, characterized in that: In steps S1 and S3, the carbonization precipitant is added directly in the form of a solid or in the form of a solution.

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