A method for preparing a sodium permanganate solution with low heavy metal and low sulfate content.

Abstract

This invention provides a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, relating to the field of inorganic chemical technology. The method involves mixing concentrated sodium permanganate solution and a desulfurizing agent for a first reaction, then mixing the resulting reactants with a pH adjuster and performing a first solid-liquid separation to obtain a clear desulfurized solution. The clear desulfurized solution is then mixed with a heavy metal adsorbent for a second reaction and a second solid-liquid separation to obtain an adsorbed solution. Finally, the adsorbed solution is mixed with a diluent for a third solid-liquid separation to obtain a sodium permanganate solution. The method first involves reacting the desulfurizing agent with the concentrated sodium permanganate solution, producing sulfate precipitates in crystalline form within the system. After adding a pH adjuster, solid-liquid separation is performed to obtain the clear desulfurized solution. The heavy metal adsorbent forms coordination bonds with the heavy metals in the clear desulfurized solution, thereby selectively separating the heavy metals from the solution. This method can meet the needs of different industries for high-quality sodium permanganate solutions.

Description

Technical Field

[0001] This application relates to the field of inorganic chemical technology, and in particular to a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content. Background Technology

[0002] Sodium permanganate (NaMnO4) is a strong oxidizing agent that is highly soluble in water. It has a wide range of applications in electronics, chemicals, drinking water treatment, aquaculture, textiles, environmental protection, animal husbandry, and military industries. With the continuous expansion of its application areas, more stringent technical requirements have been placed on the quality of sodium permanganate products.

[0003] However, the sulfate and heavy metal content in sodium permanganate solutions prepared by existing technologies is generally high. Therefore, it is crucial to provide a new method for preparing sodium permanganate solutions. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, so as to solve the above-mentioned problems.

[0005] To achieve the above objectives, this application provides a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, comprising:

[0006] The sodium permanganate concentrate and the desulfurizing agent were mixed to carry out the first reaction. The resulting reactants were mixed with a pH adjuster and then subjected to the first solid-liquid separation to obtain the desulfurized clear liquid.

[0007] The desulfurized liquid and heavy metal adsorbent are mixed to carry out a second reaction and a second solid-liquid separation to obtain the adsorbed liquid.

[0008] The adsorbed clear liquid and diluent are mixed and subjected to a third solid-liquid separation to obtain a sodium permanganate solution.

[0009] Optionally, the method for preparing the sodium permanganate concentrate includes:

[0010] Sodium fluorosilicate and potassium permanganate were mixed and subjected to a third reaction and a fourth solid-liquid separation to obtain crude sodium permanganate solution.

[0011] The crude sodium permanganate solution was evaporated and concentrated to obtain the concentrated sodium permanganate solution.

[0012] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0013] A. The mass fraction of the crude sodium permanganate solution is 9% to 15%;

[0014] B. The mass fraction of the sodium permanganate concentrate is 54%–63%.

[0015] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0016] A. The desulfurizing agent includes BaCO3 and / or Ba(OH)2;

[0017] B. The pH adjuster includes sulfuric acid.

[0018] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0019] A. The temperature of the first reaction is 50℃~80℃, and the time is 4h~6h;

[0020] B. The mixture obtained by mixing the reactants and the pH adjuster has a pH value of 6 to 6.5;

[0021] C. The pore size of the filter membrane for the first solid-liquid separation is 0.1 μm to 0.2 μm.

[0022] Optionally, the heavy metal adsorbent includes silica.

[0023] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0024] A. The temperature of the second reaction is 50℃~80℃, and the time is 1h~4h;

[0025] B. The pore size of the filter membrane for the second solid-liquid separation is 0.1 μm to 0.2 μm.

[0026] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0027] A. The mass of the desulfurizing agent is 2.0967 × the mass percentage of sulfate ions in the sodium permanganate concentrate to 2.2612 × the mass percentage of sulfate ions in the sodium permanganate concentrate.

[0028] B. The mass ratio of the desulfurized solution to the heavy metal adsorbent is 1:0.5% to 2%.

[0029] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0030] A. The diluent includes deionized water;

[0031] B. The mass fraction of the sodium permanganate solution is 40.0% to 40.2%;

[0032] C. The pore size of the filter membrane for the third solid-liquid separation is 0.1μm to 0.2μm.

[0033] Optionally, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0034] A. The potassium content in the sodium permanganate solution is less than or equal to 0.15%;

[0035] B. The chloride content in the sodium permanganate solution is less than or equal to 0.001%;

[0036] C. The water-insoluble matter content in the sodium permanganate solution is less than or equal to 0.001%;

[0037] D. The barium content in the sodium permanganate solution is less than or equal to 0.001%;

[0038] E. The lead content in the sodium permanganate solution is less than or equal to 0.0001%;

[0039] F. The cadmium content in the sodium permanganate solution is less than or equal to 0.0001%;

[0040] G. The sulfate content in the sodium permanganate solution is less than or equal to 0.001%;

[0041] H. The pH value of the sodium permanganate solution is 6-7;

[0042] I. The content of water-insoluble matter in the sodium permanganate solution is less than or equal to 0.001%.

[0043] Compared with the prior art, the beneficial effects of this application include:

[0044] The method for preparing a low-heavy-metal, low-sulfate sodium permanganate solution provided in this application involves first reacting a desulfurizing agent with concentrated sodium permanganate solution. During the reaction, sulfate precipitates are generated in crystalline form within the system. A pH adjuster is then added to adjust the pH value of the system. Solid-liquid separation is then performed to obtain a desulfurized clarified solution. A heavy metal adsorbent forms coordinate bonds with heavy metals such as Ba, Cd, and Pb in the desulfurized clarified solution, thereby selectively separating the heavy metals from the solution. Solid-liquid separation yields an adsorbed clarified solution. A diluent is added to the adsorbed clarified solution, and solid-liquid separation is performed again to obtain a low-heavy-metal, low-sulfate sodium permanganate solution. Using the method provided in this application, the prepared sodium permanganate solution can meet the needs of different industries for high-quality sodium permanganate solutions. Attached Figure Description

[0045] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0046] Figure 1 The graph shows the regression analysis model of sodium permanganate mass percentage and Baume degree.

[0047] Figure 2 The graph shows the regression analysis model of sodium permanganate mass percentage and potassium mass percentage.

[0048] Figure 3 This is a schematic diagram of the preparation process of the sodium permanganate solution with low heavy metal and low sulfate content provided in this application. Detailed Implementation

[0049] As used in this article:

[0050] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0051] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0052] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0053] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0054] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0055] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0056] This application provides a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, comprising:

[0057] The sodium permanganate concentrate and the desulfurizing agent were mixed to carry out the first reaction. The resulting reactants were mixed with a pH adjuster and then subjected to the first solid-liquid separation to obtain the desulfurized clear liquid.

[0058] The desulfurized liquid and heavy metal adsorbent are mixed to carry out a second reaction and a second solid-liquid separation to obtain the adsorbed liquid.

[0059] The adsorbed clear liquid and diluent are mixed and subjected to a third solid-liquid separation to obtain a sodium permanganate solution.

[0060] In some embodiments, the method for preparing the sodium permanganate concentrate includes:

[0061] Sodium fluorosilicate and potassium permanganate were mixed and subjected to a third reaction and a fourth solid-liquid separation to obtain crude sodium permanganate solution.

[0062] The crude sodium permanganate solution was evaporated and concentrated to obtain the concentrated sodium permanganate solution.

[0063] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0064] A. The mass fraction of the crude sodium permanganate solution is 9% to 15%;

[0065] Optionally, the mass fraction of the crude sodium permanganate solution can be 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value between 9% and 15%.

[0066] B. The mass fraction of the sodium permanganate concentrate is 54%–63%.

[0067] Optionally, the mass fraction of the sodium permanganate concentrate can be any value between 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, or 54% to 63%.

[0068] It should be noted that, under specific temperature conditions, the higher the mass percentage of sodium permanganate in the sodium permanganate concentrate, the lower the content of impurities such as potassium permanganate. A detailed analysis follows:

[0069] This application tested the regression analysis model of sodium permanganate mass percentage content and Baume degree at a temperature of 20℃. The test data are shown in Table 1, and the curves of the test results are shown in Table 1. Figure 1 As shown;

[0070] Table 1. Data from the regression analysis model of sodium permanganate mass percentage and Baume degree.

[0071]

[0072]

[0073] Based on the regression analysis model of sodium permanganate mass percentage and Baume degree, the regression analysis model of potassium mass percentage and potassium mass percentage was analyzed. The test data are shown in Table 2, and the test results are plotted as follows: Figure 2 As shown;

[0074] Table 2. Regression analysis model data of sodium permanganate and potassium permanganate mass percentages.

[0075]

[0076] Therefore, when the mass content of the concentrated sodium permanganate solution after evaporation and concentration is 50%–54%, and it is diluted with deionized water to a product with a sodium permanganate content of 40.0% (mass percentage), the potassium permanganate content in this product is 0.15%–0.18% (mass percentage). When the mass content of the concentrated sodium permanganate solution after evaporation and concentration is 54%–63%, and it is diluted with deionized water to a product with a sodium permanganate content of 40.0% (mass percentage), the potassium permanganate content in this product is 0.10%–0.15% (mass percentage). In order to meet the requirement of a low heavy metal, low sulfate, high-quality sodium permanganate solution (40.0wt%–40.2wt%) with a potassium mass content of less than 0.15%, it is preferred that the mass content of the concentrated sodium permanganate solution after evaporation and concentration is 54%–63%.

[0077] It should also be noted that sodium permanganate has limited solubility in water. If the concentration of sodium permanganate in the solution is too high (greater than or equal to 65%), sodium permanganate crystals will precipitate.

[0078] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0079] A. The desulfurizing agent includes BaCO3 and / or Ba(OH)2;

[0080] For example, the chemical reaction that occurs when a desulfurizing agent removes sulfuric acid:

[0081] (1): BaCO3(s) + SO4 2- →BaSO4(s) + CO3 2- (-Q);

[0082] (2): CO3 2- +Pb 2+ +SO4 2- →PbCO3(s)+BaSO4(s)(-Q;

[0083] (3):

[0084] (4):

[0085] The solubility product constant of BaSO4(s) at 298.15 K (25℃) is Ksp = 1.08 × 10⁻⁶. -10 The solubility product constant of BaCO3(s) is Ksp = 2.58 × 10⁻⁶. -9 The solubility product constant of PbSO4(s) is Ksp = 2.53 × 10⁻⁶. -8 The solubility product constant of PbCO3(s) is Ksp = 7.4 × 10⁻⁶. -14 Based on the Ksp values ​​of the above substances at 298.15K (25℃), theoretically, reactions (1) and (2) can proceed.

[0086] The solubility product constant of BaCO3(s) at 298.15 K (25℃) is Ksp = 2.58 × 10⁻⁶. -9 The value is very small, the reaction speed is very slow, and the time taken to reach the endpoint is very long, which does not meet the requirements of large-scale industrial production.

[0087] B. The pH adjuster includes sulfuric acid.

[0088] It is important to note that sulfuric acid is chosen as a pH adjuster because the sulfate ions in sulfuric acid can react with the desulfurizing agent to form precipitates without introducing new elemental components.

[0089] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0090] A. The temperature of the first reaction is 50℃~80℃, and the time is 4h~6h;

[0091] Optionally, the temperature of the first reaction can be any value between 50℃, 60℃, 70℃, 80℃ or 50℃~80℃, and the time can be any value between 4h, 5h, 6h or 4h~6h.

[0092] Theoretically, the solubility product constant Ksp of sparingly soluble electrolytes increases with increasing temperature. Based on this principle, this application selected the desulfurization reaction temperature of the desulfurizing agent as 50℃~80℃ and the reaction time as 4~6 hours through experiments. Table 3 shows the comparison of reaction parameters at 25℃, 35℃, 50℃, 60℃, 70℃ and 80℃.

[0093] Table 3. Reaction conditions for desulfurization by desulfurizing agent and SO4 2- Relationship of content

[0094]

[0095] Based on the data in Table 3, the optimal reaction temperature for desulfurization of the selected desulfurizing agent in this application is 50℃~80℃, and the optimal reaction time is 4~6 hours.

[0096] B. The mixture obtained by mixing the reactants and the pH adjuster has a pH value of 6 to 6.5;

[0097] Optionally, the pH value of the mixture obtained by mixing the reactants and the pH adjuster can be 6, 6.1, 6.2, 6.3, 6.4, 6.5 or any value between 6 and 6.5;

[0098] Optionally, when the pH value of the mixture obtained by mixing the reactants and the pH adjuster is 6 to 6.5, it can not only meet the product requirements of the final product sodium permanganate solution, but also provide pH conditions for the subsequent reaction of heavy metal adsorbents.

[0099] C. The pore size of the filter membrane for the first solid-liquid separation is 0.1 μm to 0.2 μm.

[0100] Optionally, the pore size of the filter membrane for the first solid-liquid separation can be 0.1 μm, 0.15 μm, 0.2 μm, or any value between 0.1 μm and 0.2 μm.

[0101] It should be noted that the BaSO4 crystals and PbCO3 crystals produced in the first reaction process exist in the system in crystalline form, with crystal diameters of more than 0.2 micrometers. In order to filter out the BaCO3, BaSO4, PbCO3 and other crystals present in the reaction system, a filter with a membrane pore size of 0.1 to 0.2 micrometers is selected to filter the desulfurization liquid.

[0102] In some embodiments, the heavy metal adsorbent comprises silica.

[0103] It is important to note that silica, also known as hydrated silica or light silica, is mainly composed of silica. It is a white amorphous powder that is light and loose, insoluble in water, solvents, and acids (except hydrofluoric acid), but can react with strong alkalis. It is heat-resistant, non-flammable, tasteless, and odorless. Its molecular formula and structural formula can be represented by SiO2.nH2O, where nH2O exists as hydroxyl groups (-OH) at the interface of the three-dimensional aggregates of SiO2 molecules. The hydroxyl groups (-OH) mainly exist in three forms: adjacent hydroxyl groups (-OH), isolated hydroxyl groups (-OH), and siloxy hydroxyl groups (-OH). When the hydroxyl groups (-OH) at the interface of the three-dimensional aggregates of SiO2 molecules are oxidized to -OOH bonds in a strong oxidizing solution of sodium permanganate at a pH of 6-6.5 and a temperature of 50℃-80℃, the -OOH bonds have lone pairs of electrons and have a strong coordination ability, forming coordinate bonds with the empty orbitals of heavy metals such as barium, cadmium, and lead: (-OOH)→Ba, (-OOH)→Cd, (-OOH)→Pb.

[0104] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0105] A. The temperature of the second reaction is 50℃~80℃, and the time is 1h~2h;

[0106] Optionally, the temperature of the second reaction can be any value between 50℃, 60℃, 70℃, 80℃ or 50℃~80℃, and the time can be any value between 1h, 2h, 3h, 4h or 1h~4h.

[0107] B. The pore size of the filter membrane for the second solid-liquid separation is 0.1 μm to 0.2 μm.

[0108] Optionally, the pore size of the filter membrane for the second solid-liquid separation can be 0.1 μm, 0.15 μm, 0.2 μm, or any value between 0.1 μm and 0.2 μm.

[0109] It should be noted that since the diameter of silica (hydrated silica) particles is greater than 0.2 micrometers, a filter with a membrane pore size of 0.1 to 0.2 micrometers is used to remove heavy metal elements.

[0110] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0111] A. The mass of the desulfurizing agent is 2.0967 × the mass percentage of sulfate ions in the sodium permanganate concentrate to 2.2612 × the mass percentage of sulfate ions in the sodium permanganate concentrate.

[0112] It should be noted that the amount of desulfurizer added, 2.0967 ml × the mass percentage of sulfate ions in sodium permanganate concentrate, is greater than the theoretical weight of sulfate ions in sodium permanganate concentrate, meaning there is an excess. This excess portion exists in the system in crystalline form.

[0113] For example, a sample of sodium permanganate concentrate with a mass content of 54%–63% was first taken for analysis to determine the sulfate (SO4) content. 2- The weight percentage of ions is a. Then, a concentrated sodium permanganate solution weighing m1 kg is placed in a desulfurization reactor equipped with a stirring device, saturated steam is introduced to raise the temperature, and then 2.0967 m1×a ~ 2.2612 m1×a kg of desulfurizing agent is added.

[0114] B. The mass ratio of the desulfurized solution to the heavy metal adsorbent is 1:0.5% to 2%.

[0115] Optionally, the mass ratio of desulfurized cleaning solution to heavy metal adsorbent can be any value between 1:0.5%, 1:1%, 1:1.5%, 1:2%, or 1:0.5% to 2%.

[0116] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0117] A. The diluent includes deionized water;

[0118] B. The mass fraction of the sodium permanganate solution is 40.0% to 40.2%;

[0119] Optionally, the mass fraction of the sodium permanganate solution can be 40.0%, 40.1%, 40.2%, or any value between 40.0% and 40.2%.

[0120] C. The pore size of the filter membrane for the third solid-liquid separation is 0.1μm to 0.2μm.

[0121] Optionally, the pore size of the filter membrane for the third solid-liquid separation can be 0.1 μm, 0.15 μm, 0.2 μm, or any value between 0.1 μm and 0.2 μm.

[0122] In some embodiments, the method for preparing the sodium permanganate solution with low heavy metal and low sulfate content satisfies at least one of the following conditions:

[0123] A. The potassium content in the sodium permanganate solution is less than or equal to 0.15%;

[0124] Optionally, the potassium content in the sodium permanganate solution can be 0.01%, 0.05%, 0.1%, 0.15%, or any value less than or equal to 0.15%.

[0125] B. The chloride content in the sodium permanganate solution is less than or equal to 0.001%;

[0126] Optionally, the chloride content in the sodium permanganate solution can be 0.00001%, 0.0001%, 0.001%, or any value less than or equal to 0.001%.

[0127] C. The water-insoluble matter content in the sodium permanganate solution is less than or equal to 0.001%;

[0128] It should be noted that the water-insoluble matter content in sodium permanganate solution can be 0.00001%, 0.0001%, 0.001%, or any value less than or equal to 0.001%.

[0129] D. The barium content in the sodium permanganate solution is less than or equal to 0.001%;

[0130] Optionally, the barium content in the sodium permanganate solution can be 0.00001%, 0.0001%, 0.001%, or any value less than or equal to 0.001%.

[0131] E. The lead content in the sodium permanganate solution is less than or equal to 0.0001%;

[0132] Optionally, the lead content in the sodium permanganate solution can be 0.00001%, 0.00005%, 0.0001%, or any value less than or equal to 0.0001%.

[0133] F. The cadmium content in the sodium permanganate solution is less than or equal to 0.0001%;

[0134] Optionally, the cadmium content in the sodium permanganate solution can be 0.00001%, 0.00005%, 0.0001%, or any value less than or equal to 0.0001%.

[0135] G. The sulfate content in the sodium permanganate solution is less than or equal to 0.001%;

[0136] Optionally, the sulfate content in the sodium permanganate solution can be 0.00001%, 0.0001%, 0.001%, or any value less than or equal to 0.001%.

[0137] H. The pH value of the sodium permanganate solution is 6-7;

[0138] Optionally, the pH value of the sodium permanganate solution can be 6, 6.5, 7, or any value between 6 and 7;

[0139] I. The content of water-insoluble matter in the sodium permanganate solution is less than or equal to 0.001%.

[0140] Optionally, the water-insoluble matter content in the sodium permanganate solution can be 0.00001%, 0.0001%, 0.001%, or any value less than or equal to 0.001%.

[0141] For example, the steps of a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content provided in this application are as follows:

[0142] The prepared crude sodium permanganate solution was evaporated and concentrated to obtain a concentrated sodium permanganate solution. The concentrated sodium permanganate solution and desulfurizing agent were added to a desulfurization reactor, and saturated steam was introduced to carry out the desulfurization reaction. The reactants obtained from the desulfurization were adjusted to pH using sulfuric acid as a pH adjuster, filtered to remove solid particles, and then the resulting desulfurized clear liquid was transferred to an adsorption reactor. Hydrated silica was added to carry out a heavy metal adsorption and heat preservation reaction. After filtration, the liquid was transferred to a dilution reactor, diluted with deionized water, and filtered again to obtain the final sodium permanganate solution. The specific steps are as follows: Figure 3 As shown.

[0143] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0144] The sodium permanganate concentrate provided in this application is prepared by reacting sodium fluorosilicate and potassium permanganate as raw materials, filtering the reactants to obtain crude sodium permanganate solution (9wt% to 15wt%), and then evaporating and concentrating the crude sodium permanganate solution to obtain concentrated sodium permanganate solution (54% to 63%).

[0145] The sodium permanganate concentrates used in the examples and comparative examples were prepared from the same batch of products. The specific substance content of the sodium permanganate concentrates is shown in Table 4.

[0146] Table 4. Substance content of sodium permanganate concentrate

[0147]

[0148]

[0149] Example 1

[0150] This embodiment provides a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, the specific steps of which include:

[0151] S1, Desulfate removal: Add 5 tons of concentrated sodium permanganate solution to the desulfurization reactor, and take a sample for analysis. The sodium permanganate content is 54.2% (mass percentage), and the sulfate content (SO4) is...2- The ion content was 0.0196% (mass percentage). Stirring was started, and the temperature was raised to 50℃ by saturated steam. Then, 2.0967 × 5000 × 0.0196% = 2.055 kg of barium carbonate was added, and the mixture was stirred and kept at this temperature for 6 hours. Samples were taken at 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours to analyze the sulfate (SO4) content. 2- The mass percentage of ions is shown in Table 5.

[0152] Table 5. Mass percentage of sulfate ions during desulfate removal process.

[0153] reaction time 1 hour 2 hours 3 hours 4 hours 5 hours 6 hours <![CDATA[SO4 2- / wt%]]> 0.0116 0.0054 0.0015 0.0009 0.0008 0.0008

[0154] S2. Add an appropriate amount of 30% (mass percentage) sulfuric acid to the reactants obtained in step S1, adjust the pH of the solution to 6.2, filter the solution using a filter with a pore size of 0.2 micrometers to obtain desulfurized clear liquid, and take samples of the desulfurized clear liquid for analysis. The mass percentage of each component in the desulfurized clear liquid is shown in Table 6.

[0155] Table 6. Mass percentage of each component in the desulfurization solution

[0156] <![CDATA[NaMnO4]]> <![CDATA[SO4 2- ]]> <![CDATA[Cl - ]]> Ba Cd Pb 50.1％ 0.0009％ 0.0010％ 0.0092％ 0.0015％ 0.0010％

[0157] S3. Adsorption of heavy metals: 5.41 tons of the above desulfurized liquid were transferred into the adsorption vessel, stirring was started, and the temperature was kept to 50°C. Then 27.1 kg of fumed silica (hydrated silicon dioxide) was added, and the mixture was stirred and kept at the temperature for 4 hours. Samples were taken at 1 hour, 2 hours, 3 hours and 4 hours to analyze the mass percentage of each component, as shown in Table 7.

[0158] Table 7. Mass percentage of each component during the heavy metal adsorption process.

[0159] Components 1 hour 2 hours 3 hours 4 hours <![CDATA[SO4 2- ]]> 0.0008％ 0.0007％ 0.0007％ 0.0007％ <![CDATA[Cl - ]]> 0.0009％ 0.0008％ 0.0008％ 0.0008％ Ba 0.0015％ 0.0010％ 0.0008％ 0.0007％ Cd 0.0003％ 0.0001％ 0.00008％ 0.00007％ Pb 0.0001％ 0.00006％ 0.00005％ 0.00005％

[0160] S4. Filter the product obtained in step S3 using a filter with a membrane pore size of 0.2 micrometers to obtain an adsorbed clear liquid;

[0161] S5. Deionized water dilution: Transfer the adsorbed clear liquid cooled to room temperature into a dilution vessel equipped with a stirrer, add an appropriate amount of deionized water to dilute to a finished sodium permanganate solution containing 40.0wt% to 40.2wt% sodium permanganate, stir evenly, and then filter using a filter with a membrane pore size of 0.2 micrometers to obtain 6.7 tons of product sodium permanganate solution with a sodium permanganate content of 40.08wt%. Take samples to analyze the mass percentage content of each component, as shown in Table 8.

[0162] Table 8. Mass percentage of each component in sodium permanganate solution

[0163]

[0164] Example 2

[0165] This embodiment provides a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, the specific steps of which include:

[0166] S1, Desulfate removal: Add 5 tons of concentrated sodium permanganate solution to the desulfurization reactor, and take a sample for analysis. The sodium permanganate content is 54.2% (mass percentage), and the sulfate content (SO4) is... 2- The ion content was 0.0196% (mass percentage). Stirring was started, and the temperature was raised to 55℃ by saturated steam. Then, 2.1500 × 5000 × 0.0196% = 2.11 kg of barium carbonate was added, and the mixture was stirred and kept at this temperature for 6 hours. Samples were taken at 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours to analyze the sulfate (SO4) content. 2- The mass percentage of ions is shown in Table 9.

[0167] Table 9. Mass percentage of sulfate ions during desulfate removal process.

[0168] reaction time 1 hour 2 hours 3 hours 4 hours 5 hours 6 hours <![CDATA[SO4 2- / wt%]]> 0.0111 0.0057 0.0013 0.0011 0.0008 0.0008

[0169] S2. Add an appropriate amount of 30% (mass percentage) sulfuric acid to the reactants obtained in step S1, adjust the pH of the solution to 6.3, filter it with a filter with a pore size of 0.2 micrometers to obtain desulfurized clear liquid, and take samples of the desulfurized clear liquid for analysis. The mass percentage of each component in the desulfurized clear liquid is shown in Table 10.

[0170] Table 10. Mass percentage of each component in the desulfurized cleaning liquid

[0171] <![CDATA[NaMnO4]]> <![CDATA[SO4 2- ]]> <![CDATA[Cl - ]]> Ba Cd Pb 49.8％ 0.0008％ 0.0011％ 0.0097％ 0.0017％ 0.0012％

[0172] S3. Adsorption of heavy metals: 5.44 tons of the above desulfurized liquid were transferred into the adsorption vessel, stirring was started, and the temperature was kept to 50°C. Then 30.5 kg of fumed silica (hydrated silicon dioxide) was added, and the mixture was stirred and kept at the temperature for 4 hours. Samples were taken at 1 hour, 2 hours, 3 hours and 4 hours to analyze the mass percentage of each component, as shown in Table 11.

[0173] Table 11. Mass percentage of each component during the heavy metal adsorption process.

[0174] Components 1 hour 2 hours 3 hours 4 hours <![CDATA[SO4 2- ]]> 0.0008％ 0.0007％ 0.0007％ 0.0007％ <![CDATA[Cl - ]]> 0.0009％ 0.0008％ 0.0008％ 0.0008％ Ba 0.0017％ 0.0012％ 0.0009％ 0.0007％ Cd 0.0005％ 0.0001％ 0.00008％ 0.00007％ Pb 0.0002％ 0.00007％ 0.00005％ 0.00005％

[0175] S4. Filter the product obtained in step S3 using a filter with a membrane pore size of 0.2 micrometers to obtain an adsorbed clear liquid;

[0176] S5. Deionized water dilution: Transfer the adsorbed clear liquid cooled to room temperature into a dilution vessel equipped with a stirrer, add an appropriate amount of deionized water to dilute to a finished sodium permanganate solution containing 40.0wt% to 40.2wt% sodium permanganate, stir evenly, and then filter using a filter with a membrane pore size of 0.2 micrometers to obtain 6.7 tons of finished sodium permanganate solution with a sodium permanganate content of 40.10wt%. Take samples to analyze the mass percentage content of each component, as shown in Table 12.

[0177] Table 12. Mass percentage of each component in sodium permanganate solution

[0178]

[0179] Example 3

[0180] This embodiment provides a method for preparing a sodium permanganate solution with low heavy metal and low sulfate content, the specific steps of which include:

[0181] S1, Desulfate removal: Add 5 tons of concentrated sodium permanganate solution to the desulfurization reactor, and take a sample for analysis. The sodium permanganate content is 54.2% (mass percentage), and the sulfate content (SO4) is... 2- The ion content was 0.0196% (mass percentage). Stirring was started, and the temperature was raised to 50℃ by saturated steam. Then, 2.2612 × 5000 × 0.0196% = 2.22 kg of barium carbonate was added, and the mixture was stirred and kept at this temperature for 6 hours. Samples were taken at 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours to analyze the sulfate (SO4) content. 2- The mass percentage of ions is shown in Table 13.

[0182] Table 13. Mass percentage of sulfate ions during desulfate removal process.

[0183] reaction time 1 hour 2 hours 3 hours 4 hours 5 hours 6 hours <![CDATA[SO4 2- / wt%]]> 0.0107 0.0053 0.0013 0.0011 0.0008 0.0008

[0184] S2. Add an appropriate amount of 30% (mass percentage) sulfuric acid to the reactants obtained in step S1, adjust the pH of the solution to 6.5, filter it with a filter membrane with a pore size of 0.2 micrometers to obtain desulfurized clear liquid, and take samples of the desulfurized clear liquid for analysis. The mass percentage of each component in the desulfurized clear liquid is shown in Table 14.

[0185] Table 14. Mass percentage of each component in the desulfurization solution

[0186] <![CDATA[NaMnO4]]> <![CDATA[SO4 2- ]]> <![CDATA[Cl - ]]> Ba Cd Pb 50.3％ 0.0008％ 0.0011％ 0.0105％ 0.0017％ 0.0012％

[0187] S3. Adsorption of heavy metals: 5.38 tons of the above desulfurized liquid were transferred into the adsorption vessel, stirring was started, and the temperature was kept to 55°C. Then 107.6 kg of fumed silica (hydrated silicon dioxide) was added, and the mixture was stirred and kept at the temperature for 4 hours. Samples were taken at 1 hour, 2 hours, 3 hours and 4 hours to analyze the mass percentage of each component, as shown in Table 15.

[0188] Table 15. Mass percentage of each component during the heavy metal adsorption process.

[0189] Components 1 hour 2 hours 3 hours 4 hours <![CDATA[SO4 2- ]]> 0.0008％ 0.0007％ 0.0007％ 0.0007％ <![CDATA[Cl - ]]> 0.0009％ 0.0008％ 0.0008％ 0.0008％ Ba 0.0023％ 0.0013％ 0.0009％ 0.0007％ Cd 0.0005％ 0.0001％ 0.00008％ 0.00007％ Pb 0.0002％ 0.00007％ 0.00005％ 0.00005％

[0190] S4. Filter the product obtained in step S3 using a filter with a membrane pore size of 0.2 micrometers to obtain an adsorbed clear liquid;

[0191] S5. Deionized water dilution: Transfer the adsorbed clear liquid cooled to room temperature into a dilution vessel equipped with a stirrer, add an appropriate amount of deionized water to dilute to a finished sodium permanganate solution containing 40.0wt% to 40.2wt% sodium permanganate. After stirring evenly, filter using a filter with a membrane pore size of 0.2 micrometers to obtain 6.7 tons of finished sodium permanganate solution with a sodium permanganate content of 40.15wt%. Take samples to analyze the mass percentage content of each component, as shown in Table 16.

[0192] Table 16. Mass percentage of each component in sodium permanganate solution

[0193]

[0194] Comparative Example 1

[0195] The sodium permanganate concentrate is diluted directly with clean tap water without undergoing the two-step process of desulfate treatment and heavy metal adsorption. The specific method is as follows:

[0196] Add 5 tons of concentrated sodium permanganate solution to the dilution vessel, start stirring, add an appropriate amount of clean tap water to dilute, stir evenly, and then filter using an ordinary filter press with 800 mesh filter cloth to obtain 6.7 tons of sodium permanganate solution. Take samples to analyze the mass percentage content of each component, as shown in Table 17.

[0197] Table 17. Mass percentage of each component in sodium permanganate solution

[0198]

[0199] Comparative Example 2

[0200] The difference from Example 1 is that sulfuric acid is not added after desulfate removal, but instead added after heavy metal adsorption. That is, step S2 in Example 1 is placed between steps S4 and S5. The sodium permanganate solution prepared by the above method is sampled and the mass percentage of each component is analyzed, as shown in Table 18.

[0201] Table 18. Mass percentage of each component in sodium permanganate solution

[0202]

[0203] As can be seen from Comparative Example 2, the order in which sulfuric acid is added as a pH additive cannot be changed arbitrarily.

[0204] In addition, the mass content requirements of each component in the high-quality sodium permanganate solution with low heavy metals and low sulfates are shown in Table 19.

[0205] Table 19 Requirements for the Mass Content of Each Component in High-Quality Sodium Permanganate Solution with Low Heavy Metals and Low Sulfates

[0206] project index <![CDATA[Content of sodium permanganate (NaMnO4) / (%)]]> ≧40.0 Water-insoluble matter / % ≦ ≦0.001 Potassium (K) content (%) ≦0.15 pH value 6～7 Chloride (as Cl) content (%) ≦0.001 Sulfate content (as SO4) / (%) ≦0.001 Barium (as Ba) content (%) ≦0.001 Cadmium (Cd) content (%) ≦0.0001 Lead (as Pb) content (%) ≦0.0001

[0207] analyze:

[0208] As can be seen from the above examples and comparative examples, sodium permanganate solutions that do not undergo desulfate and heavy metal adsorption processes cannot meet the performance requirements of high-quality sodium permanganate solutions with low heavy metals and low sulfates in terms of the mass content of each component.

[0209] By using the method for preparing sodium permanganate solution with low heavy metal and low sulfate content provided by this invention, the quality and technical indicators of the produced sodium permanganate solution meet the technical requirements for sodium permanganate solution with low heavy metal and low sulfate content, filling a market gap and having significant economic value.

[0210] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0211] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for the preparation of a low heavy metal, low sulfate sodium permanganate solution, characterized in that, The application relates to a preparation method of a high-concentration sodium permanganate solution. The method comprises the following steps: mixing a sodium permanganate concentrated solution and a desulfurizing agent to carry out a first reaction, mixing the obtained reaction product and a pH regulator, carrying out a first solid-liquid separation to obtain a desulfurized clear solution; Mixing the desulfurized clear solution and a heavy metal adsorbent to carry out a second reaction and a second solid-liquid separation to obtain an adsorbed clear solution; Mixing the adsorbed clear solution and a diluent to carry out a third solid-liquid separation to obtain the high-concentration sodium permanganate solution. The desulfurizing agent comprises BaCO3. The pH regulator comprises sulfuric acid. The heavy metal adsorbent is white carbon black. The preparation method of the sodium permanganate concentrated solution comprises the following steps: mixing sodium fluosilicate and potassium permanganate to carry out a third reaction, carrying out a fourth solid-liquid separation to obtain a sodium permanganate crude solution; Carrying out evaporation concentration on the sodium permanganate crude solution to obtain the sodium permanganate concentrated solution. The mass fraction of the sodium permanganate crude solution is 9% to 15%. The mass fraction of the sodium permanganate concentrated solution is 54% to 63%. The temperature of the first reaction is 50 DEG C to 80 DEG C, and the time is 4 h to 6 h. The pH value of the mixture obtained by mixing the reaction product and the pH regulator is 6 to 6.

5. The pore size of the filter membrane of the first solid-liquid separation is 0.1 mu m to 0.2 mu m.

2. The method of producing a low heavy metal, low sulfate sodium permanganate solution according to claim 1, characterized in that, At least one of the following conditions is met:

3. The method of producing a low heavy metal, low sulfate sodium permanganate solution according to claim 1, characterized in that, A. The temperature of the second reaction is 50 DEG C to 80 DEG C, and the time is 1 h to 4 h; B. The pore size of the filter membrane of the second solid-liquid separation is 0.1 mu m to 0.2 mu m. The mass ratio of the desulfurized clear solution to the heavy metal adsorbent is 1:0.005 to 0.

02.

4. The method of claim 1, wherein the low heavy metal, low sulfate sodium permanganate solution is prepared by, At least one of the following conditions is met:

5. The method for preparing a sodium permanganate solution with low heavy metal and low sulfate content according to claim 1, characterized in that, A. The diluent comprises deionized water; B. The mass fraction of the sodium permanganate solution is 40.0% to 40.2%; C. The pore size of the filter membrane of the third solid-liquid separation is 0.1 mu m to 0.2 mu m. At least one of the following conditions is met:

6. The process for the preparation of a low heavy metal, low sulphate sodium permanganate solution according to any one of claims 1 to 5, characterized in that, A. The potassium content in the sodium permanganate solution is less than or equal to 0.15%; B. The chloride content in the sodium permanganate solution is less than or equal to 0.001%; C. The water-insoluble substance content in the sodium permanganate solution is less than or equal to 0.001%; D. The barium content in the sodium permanganate solution is less than or equal to 0.001%; E. The lead content in the sodium permanganate solution is less than or equal to 0.0001%; F. The cadmium content in the sodium permanganate solution is less than or equal to 0.0001%; G. The sulfate content in the sodium permanganate solution is less than or equal to 0.001%; H. The pH value of the sodium permanganate solution is 6 to 7. ​

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