A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate

Abstract

This application relates to the field of active manganese dioxide preparation, specifically disclosing a method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate, comprising the following steps: S1, impurity removal: waste industrial manganese carbonate raw material is mixed with dilute hydrochloric acid, then fluoride is added, precipitation occurs, and the filtrate and precipitate are separated. The precipitate is calcined to obtain metal oxides. A composite adsorbent is added to the filtrate to remove fluoride, and after filtration, a saturated sodium carbonate solution is added, precipitation occurs, and filtration is performed to obtain impurity-removed manganese carbonate; S2, the impurity-removed manganese carbonate is pyrolyzed to obtain manganese dioxide; S3, the manganese dioxide is soaked in sulfuric acid solution; S4, filtration occurs, the mixture is washed with water until neutral, and dried to obtain active manganese dioxide; wherein, the composite adsorbent in step S1 is mainly composed of activated alumina, polyaluminum chloride, metal oxides, ethyl cellulose, and porous starch. This application has the characteristic of utilizing waste industrial manganese carbonate to produce active manganese dioxide, realizing waste recycling.

Description

Technical Field

[0001] This application relates to the field of active manganese dioxide preparation, and more specifically, it relates to a method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate. Background Technology

[0002] Manganese carbonate ore is a rare primary manganese ore in my country, characterized by high manganese, high sulfur, high silver, high lead, and high zinc content. After electrolytic refining, its product can be used to prepare high-purity manganese carbonate concentrate, widely applied in the steel, aluminum alloy, magnetic materials, and chemical industries. However, my country's manganese resources are scarce, and the grade of manganese ore is low. Furthermore, the electrolytic manganese process generates a massive amount of waste slag after processing manganese carbonate ore; for every ton of metallic manganese extracted, 7-8 tons of manganese carbonate slag are produced. Currently, my country's annual manganese slag discharge exceeds 2 million tons, with extremely low utilization rates. For a long time, no comprehensive and effective method has been found for the treatment of manganese slag; it has primarily relied on stockpiling or landfilling. This has led to a year-on-year increase in land use, groundwater pollution, serious waste of mineral resources, and rising production costs.

[0003] Activated manganese dioxide is produced by crushing, reducing, roasting, acid activation, and then subjecting natural manganese ore to heavy oxidation. In recent years, activated manganese dioxide has been increasingly widely used as an alternative to electrolytic manganese dioxide. Its rapid promotion is due not only to its low price, but also primarily to its excellent liquid absorption and discharge performance, especially its continuous discharge performance under heavy loads.

[0004] Most existing active manganese dioxide is prepared using manganese ore or specialized manganese solutions. However, manganese ore deposits are small in scale, mostly small to medium-sized manganese mines, with poor ore quality, complex ore bodies, and high mining difficulty. Therefore, using waste industrial manganese carbonate for refining and producing active manganese dioxide can improve the utilization rate of industrial manganese carbonate, realize waste recycling, and is of great significance for the preparation of active manganese dioxide. Summary of the Invention

[0005] In order to utilize waste industrial manganese carbonate to produce active manganese dioxide and realize waste recycling, this application provides a method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate.

[0006] This application provides a method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate, which employs the following technical solution:

[0007] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate includes the following steps:

[0008] S1. Impurity removal: Waste industrial manganese carbonate raw material is mixed with dilute hydrochloric acid, then fluoride is added, precipitation occurs, and the filtrate and precipitate are separated. The precipitate is then calcined to obtain metal oxides.

[0009] A composite adsorbent was added to the filtrate to remove fluoride. After filtration, a saturated sodium carbonate solution was added, and the precipitate was collected and filtered to obtain purified manganese carbonate.

[0010] S2. Pyrolyze the purified manganese carbonate to obtain manganese dioxide;

[0011] S3. Soak manganese dioxide in sulfuric acid solution;

[0012] S4. Filter, wash with water until neutral, dry, and obtain active manganese dioxide;

[0013] In step S1, the composite adsorbent is mainly composed of activated alumina, polyaluminum chloride, metal oxides, ethyl cellulose, and porous starch.

[0014] By adopting the above technical solution, this application first removes impurity ions, mainly calcium and magnesium, from the waste industrial manganese carbonate raw material, then pyrolyzes it to obtain manganese dioxide, and then soaks it in sulfuric acid to remove low-valence manganese and other impurities from the system. Finally, it is washed and dried to obtain active manganese dioxide. This realizes the production of active manganese dioxide from waste industrial manganese carbonate as raw material, realizing waste utilization. Moreover, it provides a new route for the preparation of active manganese dioxide. In addition, by soaking manganese dioxide in sulfuric acid, low-valence manganese and other impurities are directly removed without the need for valence enhancement to achieve the requirements of active manganese dioxide, reducing the number of processing steps.

[0015] In this application, during the purification process of waste industrial manganese carbonate raw materials, it is first mixed with dilute hydrochloric acid to obtain a solution mainly composed of manganese chloride, calcium chloride, and magnesium chloride. Then, fluoride precipitates are added to obtain calcium fluoride and magnesium fluoride insolubles, thereby achieving the separation of manganese fluoride and calcium fluoride from manganese fluoride. The result is a filtrate mainly composed of manganese fluoride and calcium fluoride and magnesium fluoride precipitates. To address the problem that the introduction of fluoride ions in the filtrate can easily be adsorbed into the product, leading to excessive fluoride content, this application adds a composite adsorbent to the filtrate for fluoride removal. The activated alumina in the composite adsorbent adsorbs fluoride ions in the filtrate through adsorption, while the flocculation effect of polyaluminum chloride removes fluoride ions from the filtrate. The precipitate is then calcined to obtain calcium oxide and magnesium oxide, which are then added as composite adsorbents. The calcium and magnesium ions formed after being added to the filtrate react with the fluoride ions in the filtrate to form calcium fluoride and magnesium fluoride precipitates, thereby achieving fluoride ion removal and waste recycling, and reducing the amount of activated alumina and other additives required.

[0016] Optionally, the pyrolysis temperature in step S2 is 300-400℃, and the pyrolysis time is 1-2h.

[0017] Optionally, in step S3, the sulfuric acid soaking temperature is 40-60℃ and the soaking time is 1-1.5h.

[0018] Optionally, the composite adsorbent is prepared from the following raw materials in parts by weight:

[0019] 20-30 parts activated alumina, 10-15 parts polyaluminum chloride, 30-45 parts metal oxides, 8-15 parts ethyl cellulose, 10-18 parts ethanol, and 30-40 parts porous starch.

[0020] Optionally, the composite adsorbent is prepared by the following method:

[0021] Activated alumina, polyaluminum chloride, and metal oxides were ground and mixed to obtain a solid mixture;

[0022] Ethyl cellulose was mixed with ethanol and stirred. Then, a solid mixture and porous starch were added and stirred to obtain a paste. The paste was granulated and dried to obtain a composite adsorbent.

[0023] By adopting the above technical solution, the composite adsorbent in this application, when using aluminum salt for fluoride removal, is combined with calcium-containing metal oxides to form a complex composed of calcium, fluoride, and aluminum, which has a better removal effect on fluoride. Furthermore, porous starch and ethyl cellulose are added during its preparation. Ethyl cellulose, dissolved in ethanol, combines with aluminum salt and starch to form a framework with pores of various sizes. The aluminum salt can be loaded onto the porous starch, thereby increasing the contact area between the adsorbent and the filtrate, increasing the specific surface area, and thus improving the fluoride removal effect. Moreover, after the composite adsorbent adsorbs and removes fluoride in the filtrate, adjacent adsorbent particles easily settle due to hydrogen bonding between ethyl cellulose and porous starch, resulting in an even better fluoride removal effect.

[0024] Optionally, the amount of composite adsorbent added is 3-5 wt% of the filtrate.

[0025] Optionally, the fluoride in step S1 may be one or both of ammonium fluoride and sodium fluoride.

[0026] Optionally, in step S1, the calcination temperature of the precipitate is 800-900℃, and the calcination time is 2-3h.

[0027] Optionally, the pH value of the mixture obtained by mixing the waste industrial manganese carbonate raw material with dilute hydrochloric acid in step S1 is 4-4.5.

[0028] By adopting the above technical solution, a lower pH value of 4-4.5 is more conducive to the adsorption and removal of fluoride, resulting in a better fluoride removal effect.

[0029] Optionally, in step S1, the obtained purified manganese carbonate is washed sequentially with ammonium chloride solution and liquid ammonia before proceeding to step S2.

[0030] By adopting the above technical solution, manganese carbonate is insoluble in liquid ammonia, while calcium carbonate and magnesium carbonate are soluble in ammonium chloride solution. In this application, the manganese carbonate in step S1 is first washed with ammonium chloride solution to remove the small amount of calcium carbonate and magnesium carbonate that were not completely removed from the manganese carbonate. Then it is washed with liquid ammonia to further remove impurities from the manganese carbonate and obtain manganese carbonate with higher purity.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. In this application, waste industrial manganese carbonate raw material is first purified to remove impurity ions, mainly calcium and magnesium, and then pyrolyzed to obtain manganese dioxide. Then, it is soaked in sulfuric acid to remove low-valence manganese and other impurities in the system. Finally, it is washed and dried to obtain active manganese dioxide. This realizes the use of waste industrial manganese carbonate as raw material to produce active manganese dioxide, realizes waste utilization, and provides a new route for the preparation of active manganese dioxide.

[0033] 2. In the process of removing impurities from waste industrial manganese carbonate raw materials in this application, it is first mixed with dilute hydrochloric acid to obtain a solution mainly composed of manganese chloride, calcium chloride, and magnesium chloride. Then, fluoride precipitates are added to obtain calcium fluoride and magnesium fluoride insolubles, thereby achieving the separation of manganese fluoride and calcium fluoride from manganese fluoride. The result is a filtrate mainly composed of manganese fluoride and calcium fluoride and magnesium fluoride precipitates. A composite adsorbent is added to the filtrate for fluoride removal. The activated alumina in the composite adsorbent adsorbs fluoride ions in the filtrate through adsorption, and at the same time, the flocculation effect of polyaluminum chloride removes fluoride ions from the filtrate. The precipitates are calcined to obtain calcium oxide and magnesium oxide, which are then added as composite adsorbents. The calcium and magnesium ions formed after being added to the filtrate will react with the fluoride ions in the filtrate to form calcium fluoride and magnesium fluoride precipitates, thereby achieving the removal of fluoride ions and realizing the recycling of waste, reducing the amount of activated alumina and other additives.

[0034] 3. In this application, the composite adsorbent uses aluminum salts for fluoride removal, combined with calcium-containing metal oxides to form a complex of calcium, fluoride, and aluminum, which exhibits better fluoride removal efficiency. Furthermore, porous starch and ethyl cellulose are added during preparation. Ethyl cellulose, dissolved in ethanol, combines with aluminum salts and starch to form a framework with pores of various sizes. The aluminum salts can be loaded onto the porous starch, increasing the contact area between the adsorbent and the filtrate, thus increasing the specific surface area and further enhancing fluoride removal. Moreover, after the composite adsorbent removes fluoride from the filtrate, adjacent adsorbent particles easily settle due to hydrogen bonding between ethyl cellulose and porous starch, resulting in even better fluoride removal.

[0035] 4. In this application, the manganese carbonate in step S1 is first washed with ammonium chloride solution to remove any remaining small amounts of calcium carbonate and magnesium carbonate. Then it is washed with liquid ammonia to further remove impurities from the manganese carbonate, resulting in manganese carbonate with higher purity. Detailed Implementation

[0036] The following detailed description of this application is provided in conjunction with the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments are all from commercially available sources.

[0037] The porous starch used in the following examples is from Bolin Biotechnology, with product number BL-2022508008.

[0038] Example 1

[0039] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate includes the following steps:

[0040] S1. Impurity removal: The waste industrial manganese carbonate raw material is mixed with dilute hydrochloric acid with a mass concentration of 10% and the pH value of the mixture is 4. Then sodium fluoride is added to precipitate the mixture. The amount of sodium fluoride added is increased until no more precipitation occurs. The filtrate and precipitate are separated. The precipitate is calcined to obtain metal oxides. The calcination temperature of the precipitate is 850℃ and the calcination time is 2.5h.

[0041] A composite adsorbent is added to the filtrate to remove fluoride. The amount of composite adsorbent added is 4 wt% of the filtrate. After filtration, a saturated sodium carbonate solution is added to precipitate the filtrate. The saturated sodium carbonate solution is added until no more precipitate is formed. After filtration, manganese carbonate with impurities removed is obtained. The waste industrial manganese carbonate is initially purified to achieve a certain purity.

[0042] The composite adsorbent is prepared by the following method:

[0043] 25 kg of activated alumina, 12 kg of polyaluminum chloride and 38 kg of precipitate were calcined and then ground and mixed to obtain a solid mixture.

[0044] 10 kg of ethyl cellulose was mixed with 15 kg of 80 wt% ethanol and stirred. Then, a solid mixture and 35 kg of porous starch were added and stirred to obtain a paste. The paste was granulated and dried to obtain a composite adsorbent.

[0045] S2. Manganese carbonate after impurity removal is pyrolyzed in a fluidized bed furnace to obtain manganese dioxide. The pyrolysis temperature is 350℃ and the pyrolysis time is 1.5h.

[0046] S3. Soak manganese dioxide in a 37wt% sulfuric acid solution at a temperature of 50℃ for 80 minutes.

[0047] S4. Filter, wash with water until neutral, dry, and after pyrolysis and acid washing, some impurities and manganese dioxide remain in the manganese carbonate to obtain active manganese dioxide.

[0048] Example 2

[0049] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate includes the following steps:

[0050] S1. Impurity removal: The waste industrial manganese carbonate raw material is mixed with dilute hydrochloric acid with a mass concentration of 10%. The pH value of the mixture is 4. Then sodium fluoride is added to precipitate the mixture. The amount of sodium fluoride added is increased until no more precipitation occurs. The filtrate and precipitate are separated. The precipitate is calcined to obtain metal oxides. The calcination temperature of the precipitate is 800℃ and the calcination time is 3h.

[0051] A composite adsorbent is added to the filtrate to remove fluoride. The amount of composite adsorbent added is 3 wt% of the filtrate. After filtration, a saturated sodium carbonate solution is added to precipitate the filtrate. The saturated sodium carbonate solution is added until no more precipitate is formed. After filtration, manganese carbonate with impurities removed is obtained. The waste industrial manganese carbonate is initially purified to achieve a certain purity.

[0052] The composite adsorbent is prepared by the following method:

[0053] 20 kg of activated alumina, 10 kg of polyaluminum chloride and 30 kg of precipitate obtained by calcination were ground and then mixed to obtain a solid mixture.

[0054] 8 kg of ethyl cellulose was mixed with 10 kg of 80 wt% ethanol and stirred. Then, a solid mixture and 30 kg of porous starch were added and stirred to obtain a paste. The paste was granulated and dried to obtain a composite adsorbent.

[0055] S2. The purified manganese carbonate is pyrolyzed in a fluidized bed furnace to obtain manganese dioxide. The pyrolysis temperature is 300℃ and the pyrolysis time is 2h. S3. The manganese dioxide is soaked in a 37wt% sulfuric acid solution at a temperature of 40℃ for 1.5h.

[0056] S4. Filter, wash with water until neutral, dry, and after pyrolysis and acid washing, some impurities and manganese dioxide remain in the manganese carbonate to obtain active manganese dioxide.

[0057] Example 3

[0058] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate includes the following steps:

[0059] S1. Impurity removal: The waste industrial manganese carbonate raw material is mixed with dilute hydrochloric acid with a mass concentration of 10%. The pH value of the mixture is 4.5. Then sodium fluoride is added to precipitate the mixture. The amount of sodium fluoride added is increased until no more precipitation occurs. The filtrate and precipitate are separated. The precipitate is calcined to obtain metal oxides. The calcination temperature of the precipitate is 900℃ and the calcination time is 2h.

[0060] A composite adsorbent is added to the filtrate to remove fluoride. The amount of composite adsorbent added is 5 wt% of the filtrate. After filtration, a saturated sodium carbonate solution is added to precipitate the filtrate. The saturated sodium carbonate solution is added until no more precipitate is formed. After filtration, manganese carbonate with impurities removed is obtained. The waste industrial manganese carbonate is initially purified to achieve a certain purity.

[0061] The composite adsorbent is prepared by the following method:

[0062] 30 kg of activated alumina, 15 kg of polyaluminum chloride and 45 kg of precipitate were calcined and then ground and mixed to obtain a solid mixture.

[0063] 15 kg of ethyl cellulose was mixed with 18 kg of 80 wt% ethanol and stirred. Then, a solid mixture and 40 kg of porous starch were added and stirred to obtain a paste. The paste was granulated and dried to obtain a composite adsorbent.

[0064] S2. The purified manganese carbonate is pyrolyzed in a fluidized bed furnace to obtain manganese dioxide. The pyrolysis temperature is 400℃ and the pyrolysis time is 1h. S3. The manganese dioxide is soaked in a 37wt% sulfuric acid solution at a soaking temperature of 60℃ for 1h.

[0065] S4. Filter, wash with water until neutral, dry, and after pyrolysis and acid washing, some impurities and manganese dioxide remain in the manganese carbonate to obtain active manganese dioxide.

[0066] Example 4

[0067] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that the pH value of the mixture after mixing the waste industrial manganese carbonate raw material with dilute hydrochloric acid in step S1 is 5.5.

[0068] Example 5

[0069] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that in step S1, the obtained impurity-removed manganese carbonate is washed with a 20wt% ammonium chloride solution before proceeding to step S2.

[0070] Example 6

[0071] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that in step S1, the obtained impurity-removed manganese carbonate is cleaned with liquid ammonia before step S2.

[0072] Example 7

[0073] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that in step S1, the obtained purified manganese carbonate is washed sequentially with 20wt% ammonium chloride solution and liquid ammonia before proceeding to step S2.

[0074] Comparative Example 1

[0075] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that the waste industrial manganese carbonate in step S1 is not purified and is directly subjected to the pyrolysis step in step S2.

[0076] Comparative Example 2

[0077] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that no metal oxide is added to the composite adsorbent.

[0078] Comparative Example 3

[0079] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that ethyl cellulose is not added to the composite adsorbent.

[0080] Comparative Example 4

[0081] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that porous starch is not added to the composite adsorbent raw material.

[0082] Comparative Example 5

[0083] A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate is carried out according to the method in Example 1, except that the metal oxides in the composite adsorbent are replaced with calcium chloride in equal amounts.

[0084] Performance testing

[0085] The active manganese dioxide obtained in this application was tested for manganese dioxide content, as well as the contents of impurities calcium and magnesium, fluorine, and heavy metal impurity iron. The test results are shown in Table 1 below:

[0086] Table 1:

[0087]

[0088] Continued from Table 1:

[0089]

[0090] Referring to the results in Table 1 above, it can be seen that the active manganese dioxide prepared in this application has a high manganese dioxide content, low calcium and magnesium impurity content, and even lower content of heavy metal impurities such as Fe and Cu.

[0091] Based on the test results of Examples 1 and 4, when the pH value of the mixed solution after adding dilute hydrochloric acid in Example 4 was 5.5, its effect on removing impurities from calcium and magnesium was reduced compared to Example 1. Furthermore, based on the test results of Examples 5-7, the effect on removing impurities from calcium and magnesium was further improved after the manganese carbonate obtained in step S1 was washed with ammonium chloride solution and / or liquid ammonia solution. Referring to the test results of Example 1 and Comparative Example 1, when manganese carbonate in Comparative Example 1 was not purified, its calcium and magnesium impurity content was high, and its manganese dioxide content was significantly reduced. Combining the test results of Comparative Example 2 and Comparative Example 5, it can be seen that when no metal oxide was added in Comparative Example 2, its calcium and magnesium removal effect was reduced, its manganese dioxide content was reduced, and its fluorine content was relatively high. However, when the metal oxide was replaced with an equal amount of calcium chloride in Comparative Example 5, it can be seen that its fluorine content was comparable to that of Example 1, its calcium content was slightly higher, and its manganese dioxide content was slightly lower. Moreover, waste utilization was also achieved in this application. Referring to the test results of Example 1, Comparative Example 3, and Comparative Example 4, when ethyl cellulose and porous starch were not added to the composite additive, its fluorine removal effect was significantly reduced.

[0092] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate, characterized in that, Includes the following steps: S1. Impurity removal: waste industrial manganese carbonate raw material is mixed with dilute hydrochloric acid, then fluoride is added, precipitation occurs, and the filtrate and precipitate are separated. The precipitate is then roasted to obtain metal oxides. A composite adsorbent was added to the filtrate to remove fluoride. After filtration, a saturated sodium carbonate solution was added, and the precipitate was collected and filtered to obtain purified manganese carbonate. S2. Pyrolyze the purified manganese carbonate to obtain manganese dioxide; S3. Soak manganese dioxide in sulfuric acid solution; S4. Filter, wash with water until neutral, dry, and obtain active manganese dioxide; In step S1, the composite adsorbent is prepared from the following raw materials in parts by weight: 20-30 parts activated alumina, 10-15 parts polyaluminum chloride, 30-45 parts metal oxides, 8-15 parts ethyl cellulose, 10-18 parts ethanol, 30-40 parts porous starch; The pH value of the mixture obtained by mixing the waste industrial manganese carbonate raw material with dilute hydrochloric acid in step S1 is 4-4.5; In step S1, the obtained purified manganese carbonate is washed sequentially with ammonium chloride solution and liquid ammonia before proceeding to step S2. The composite adsorbent is prepared by the following method: Activated alumina, polyaluminum chloride, and metal oxides were ground and mixed to obtain a solid mixture; Ethyl cellulose was mixed with ethanol and stirred. Then, a solid mixture and porous starch were added and stirred to obtain a paste. The paste was granulated and dried to obtain a composite adsorbent; The amount of composite adsorbent added is 3-5 wt% of the filtrate.

2. The method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate according to claim 1, characterized in that: In step S2, the pyrolysis temperature is 300-400℃ and the pyrolysis time is 1-2h.

3. The method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate according to claim 1, characterized in that: In step S3, the sulfuric acid soaking temperature is 40-60℃, and the soaking time is 1-1.5h.

4. The method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate according to claim 1, characterized in that: The fluoride used in step S1 can be one or both of ammonium fluoride and sodium fluoride.

5. The method for preparing high-performance active manganese dioxide from by-product industrial manganese carbonate according to claim 1, characterized in that: In step S1, the calcination temperature of the precipitate is 800-900℃, and the calcination time is 2-3h.

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