Manganese-containing material treatment method

Abstract

According to an example aspect of the present invention, there is provided a method of treating a manganese-containing material, comprising: a) leaching the manganese-containing material with sulfuric acid and hydrogen peroxide to produce a first treatment solution comprising manganese sulfate, filtering the first treatment solution, b) measuring the conductivity of the first treatment solution at a temperature, c) determining a manganese concentration based on the conductivity of the first treatment solution measured at the temperature and a correlation between the conductivity and the concentration, d) adding a persulfate according to the determined manganese concentration to produce a second treatment solution and precipitating at least a portion of the manganese oxide, and e) filtering the manganese oxide to produce a manganese-lean treatment solution.

Description

field

[0001] The present invention relates to a method for treating manganese-containing materials, in particular to a method for precipitating manganese oxide by oxidation in a hydrometallurgical process of manganese-containing materials. The present invention also relates to a device for treating manganese-containing materials. Background and Purpose

[0002] Pure manganese is usually leached from the ore by sulfuric acid followed by electrolytic precipitation, which produces manganese dioxide. Approximately 80% of the discovered recoverable manganese resources are located in South Africa, with other notable deposits in Ukraine, Australia, India, China and Brazil. In addition, it is estimated that the seafloor contains 500 billion tons of manganese nodules, of which approximately 25% is manganese.

[0003] Manganese is used in a variety of metallurgical applications where there are no viable substitutes for it. For example, manganese is widely used in steel and aluminum alloys, alkaline and lithium-ion batteries, and as a pigment for ceramics and glass.

[0004] Ammonium persulfate is a strong oxidizing agent commonly used in polymer chemistry or as a standard ingredient in bleaching agents. Ammonium persulfate is produced by electrolysis of acidic ammonium sulfate or ammonium bisulfate solutions at high current densities, usually using a platinum or boron-doped diamond (BDD) cathode. Other persulfates are monoprotic salts, such as sodium persulfate, potassium persulfate or lithium persulfate.

[0005] The use of persulfate for the precipitation of manganese oxide has been used in publications CN111092195A and CN112897584A to produce composite materials, such as lithium-rich cathode materials or Ag-TiO2-MnO2 composite materials. In these publications, the manganese content of the feed material is well known and controlled by always feeding the same amount of manganese, so the dosage of persulfate can be kept constant. Therefore, the reaction time is also always known and can be optimized for the process. These patents are not about pursuing the success rate of manganese precipitation, but about producing manganese products.

[0006] In publication CN109668941A, conductivity is used as an indicator of the amount of alkali added in sulfuric acid titration during electrolytic manganese dioxide production. During electrolytic manganese production, manganese sulfate is electrolyzed to produce solid manganese oxide and sulfuric acid. By titrating the sulfuric acid, the recovery of manganese can be calculated. During the addition of alkali, the conductivity is measured, and using the data from previous experiments, the amount to be added can be determined by comparing the values. This is not an online measurement, so it requires more work and a longer preparation time from sampling to results.

[0007] During the precipitation process, the manganese content may vary over a wide range, depending on the raw materials and formulations used in the leaching step before precipitation. For example, when recovering metals during lithium-ion battery recycling, the manganese content will vary depending on the positive electrode chemistry of the lithium-ion battery. An object of the present invention is to provide a method for accurately measuring the manganese content so that persulfate is not excessive or insufficient. In addition, the reaction time may also vary greatly when different amounts of manganese are precipitated. Another object of some embodiments of the present invention is to provide a method for accurately, online and quickly determining the manganese content before and after treatment and during treatment. Summary of the invention

[0008] According to a first aspect of the present invention, there is provided a method for treating a manganese-containing material, comprising: a) leaching a manganese-containing material using sulphuric acid and hydrogen peroxide to produce a first process solution comprising manganese sulphate, filtering the first process solution, b) measuring the conductivity of the first process solution at a certain temperature, c) determining a manganese concentration based on said conductivity of the first process solution measured at said temperature and a correlation between said conductivity and concentration, d) adding persulfate based on the determined manganese concentration to produce a second treatment solution and precipitating at least a portion of the manganese oxide, and e) filtering the manganese oxide to produce a manganese depleted process liquor.

[0009] According to a second aspect of the present invention, there is provided a device for processing manganese-containing materials, the device comprising: - a reactor for containing a manganese-containing material, sulfuric acid and hydrogen peroxide, configured to produce a first treatment solution comprising manganese sulfate, - a conductivity measuring device configured to measure the conductivity of said first process solution at a certain temperature, a calculation unit configured to determine a manganese concentration based on said conductivity of said first treatment solution at said temperature and a correlation between said conductivity and concentration, a persulfate feed pump configured to add persulfate according to the determined manganese concentration to produce a second treatment solution and to precipitate at least a portion of the manganese oxide, and - a filter configured to filter the manganese oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A method for treating a manganese-containing material according to a first embodiment is shown;

[0011] Figure 2A method for treating a manganese-containing material according to a second embodiment is shown;

[0012] Figure 3 A method for treating a manganese-containing material according to a third embodiment is shown;

[0013] Figure 4 A method for treating a manganese-containing material according to a fourth embodiment is shown;

[0014] Figure 5 A processing device for manganese-containing materials according to an embodiment is shown; and

[0015] Figure 6 A typical conductivity versus manganese concentration plot is shown. Example

[0016] In this context, the term "manganese-containing material" refers to a material containing manganese. The manganese-containing material may be, for example, a lithium-ion (Li-ion) electrode material or a black mass recovered from a lithium-ion battery. The lithium-ion electrode material or the black mass may include varying amounts of manganese, as well as other metals such as nickel, cobalt and lithium.

[0017] This example relates to the precipitation of manganese from a sulfate medium. It was found that the conductivity was directly correlated to the manganese concentration in the sulfate treatment solution: low conductivity values ​​were associated with higher manganese concentrations and vice versa. Therefore, the conductivity of the sulfate treatment solution can be accurately used to determine the amount of manganese and the dosage of persulfate required to precipitate soluble manganese. The process can be followed online without the need for expensive analytical equipment or downtime, which can ensure that the manganese has been completely precipitated before releasing the treatment solution for subsequent stages of the treatment method. "Completely" means at least 90 wt-% of the manganese has been precipitated, preferably at least 95 wt-%, and more preferably at least 99 wt-% of the manganese has been precipitated.

[0018] According to one aspect, a method for treating a manganese-containing material comprises: a) leaching a manganese-containing material using sulphuric acid and hydrogen peroxide to produce a first process solution comprising manganese sulphate, filtering the first process solution, b) measuring the conductivity of the first process solution at a certain temperature, c) determining a manganese concentration based on the conductivity of the first process solution measured at the temperature and a correlation between the conductivity and the concentration, d) adding persulfate based on the determined manganese concentration to produce a second treatment solution and precipitating at least a portion of the manganese oxide, and e) filtering the manganese oxide to produce a manganese-depleted treatment solution.

[0019] The method enables online tracking of the process without the need for expensive analytical equipment or downtime. In addition, the method ensures that the manganese has been completely precipitated before releasing the treatment solution for subsequent stages of the treatment method. The method reduces the risk of off-spec products and reduces operating expenses by optimizing reagent quantities, optimizing reaction times, and reducing operating expenses. Likewise, capital expenditures can be reduced by using low-cost equipment and software instead of other expensive online analytical methods such as X-ray fluorescence (XRF) or inductively coupled plasma optical emission spectroscopy (ICP-OES).

[0020] In step a), a manganese-containing material, such as a lithium ion (Li-ion) electrode material or a black substance, is dissolved in a sulfuric acid medium. The manganese-containing material may also include, for example, nickel, cobalt and / or lithium, as well as other elements commonly found in manganese treatment. After dissolution, the manganese concentration in the sulfuric acid medium is 0-15 g / l, preferably 1-10 g / l.

[0021] Alternatively, the manganese-containing material may be processed by other types of hydrometallurgical processes, such as electrowinning or non-oxidative precipitation.

[0022] The conductivity measurement of the first treatment solution in step b) can be carried out by a conductivity measuring device (e.g., a conductivity electrode). The conductive electrode can be connected to a reactor containing the first treatment solution. The conductive electrode can be placed inside the reactor so that it contacts the first treatment solution. The conductive electrode provides a simple and low-cost method for measuring conductivity online.

[0023] In step b), the conductivity of the first treatment solution may be measured at a temperature of 15-90°C, preferably 70-90°C, more preferably 75-85°C. Most preferably, the conductivity is measured at a temperature of 70-90°C, preferably 80°C, since precipitation of manganese oxide is usually carried out at a temperature of 80°C. However, the conductivity may also be measured at lower temperatures. The conductivity varies with temperature, so it is important to measure the conductivity at or at least close to the temperature at which the precipitation of manganese oxide is carried out. "Close" means that the temperature is within + / - 5°C of the target temperature.

[0024] In step c), the manganese concentration can be determined by comparing the conductivity of the first treatment solution with a database. The database is pre-constructed by measuring the conductivity of manganese solutions with known manganese contents at specific temperatures and plotting the conductivity versus manganese content at specific temperatures. Thus, when the conductivity is measured for a solution with an unknown manganese content, the database can be used to determine the manganese concentration.

[0025] A database can be constructed by determining the conductivity and concentration values ​​of treatment solution samples with known manganese content. The conductivity can be determined using a conductivity measuring device such as a conductivity electrode. The concentration can be determined using an accurate analytical method such as XRF or ICP-OES. A predictive database can then be constructed by plotting the conductivity of the treatment solution samples against the manganese concentration of these treatment solution samples and determining the slope and intercept. This database can be used to determine the manganese concentration during precipitation using only conductivity as an indicator. Using this method, the dosage of persulfate can be determined and the process can be tracked in real time, thereby optimizing the use of reagents and reaction times. Therefore, the database can be used online to determine the dosage of each batch of persulfate and track the changes in manganese concentration during precipitation.

[0026] Step d) may further comprise heating the first treatment solution to 70-90°C, preferably 75-85°C, before adding the persulfate, because the precipitation of manganese oxide usually occurs at around 80°C.

[0027] In step d), the required stoichiometric amount of persulfate can be determined according to the following chemical equation: MnSO4+X2S2O8+H2O→MnO2+Li2SO4+H2SO4, wherein X2S2O8 is persulfate.

[0028] The molar ratio of persulfate to manganese sulfate may be 0.95-1.3:1, preferably 1-1.1:1.

[0029] The persulfate may be a monoprotic persulfate.

[0030] X in the persulfate X2S2O8 may be Na, NH4, K or Li. Thus, the persulfate may be sodium persulfate, ammonium persulfate, potassium persulfate or lithium persulfate.

[0031] In step d), persulfate is added to the reactor. As the precipitation reaction is endothermic, it is recommended to pay close attention to the temperature to ensure that the reaction is carried out under optimal conditions (70-90°C).

[0032] Prior to the addition of persulfate, the conductivity is typically in the range of 3-8 mS / cm, depending on the manganese concentration. Once the manganese sulfate is completely precipitated as manganese oxide, the conductivity increases to 9-11 mS / cm. Increased temperature decreases the conductivity. After the addition of persulfate, the conductivity of the second process solution can be continuously measured and compared to a database. Once the desired conductivity is achieved, the second process solution can be filtered to remove solid manganese oxide from the second process solution and produce a manganese-depleted process solution. "Depleted" means that at least 90 wt-% of the manganese is precipitated, preferably at least 95 wt-%, and more preferably at least 99 wt-% of the manganese is precipitated.

[0033] The method may further comprise a step d') after step d), wherein steps b), c) and d) are repeated to precipitate a third treatment solution, wherein the third treatment solution is obtained after precipitation of the second treatment solution. Step d') may be performed if the desired conductivity is not achieved after the addition of persulfate. Thus, step d') enables the precipitation of manganese sulfate present in the second treatment solution as manganese oxide after the addition of persulfate.

[0034] The second treatment solution may also be filtered to remove solid manganese oxide to obtain a third treatment solution. Thus, optionally, step e) may also be performed before step d'). However, it is not necessary to remove the solid manganese oxide, as the solid manganese oxide has no significant effect on the conductivity of the third treatment solution.

[0035] The method may further comprise a step f) for determining the manganese concentration of the solution obtained after precipitation and filtration using an analytical method. Thus, the manganese concentration in the second or third process solution may be double checked using an analytical method such as XRF or ICP-OES. Thus, step f) may ensure that all manganese is precipitated in the form of manganese oxide.

[0036] The method comprising step f) may also include improving the determination of the manganese concentration using the manganese concentration determined using the online analytical method. Thus, the value determined using the online analytical method may be added to the database to collect more data on the manganese concentration at a given conductivity.

[0037] The database can be constructed to account for the effects of other elements present in the solution. For example, a manganese-containing material may also include nickel, cobalt, and lithium. The database includes the measured conductivity and the corresponding manganese concentration as well as different manganese concentrations. Using this data, the slope and intercept are calculated. The manganese concentration can then be determined by inputting the conductivity using the following equation: [Mn] = (conductivity - slope) / intercept The manganese concentration can be determined by comparing the conductivity of the first process solution to a database. The database is pre-constructed by measuring the conductivity of manganese-containing process solutions with known manganese contents at specific temperatures and plotting the conductivity versus manganese content at the specific temperatures. Thus, when the conductivity is measured for a solution with an unknown manganese content, the manganese concentration can be determined using the database.

[0038] The method may further comprise a step g) for releasing the treated solution to the next step when the conductivity of the solution obtained after precipitation and filtration reaches a threshold value. Thus, once the desired conductivity is reached, the treated solution may be released to the next step and the reactor may be filled with a new batch of manganese-containing material.

[0039] The threshold value may be, for example, above 9.5 mS / cm, preferably 9.5-12 mS / cm, more preferably 9.5-11 mS / cm. The threshold value may vary depending on the raw materials and process parameters.

[0040] According to another aspect, a device for processing manganese-containing materials comprises: - a reactor for containing a manganese-containing material, sulfuric acid and hydrogen peroxide, configured to produce a first treatment solution comprising manganese sulfate, - a conductivity measuring device configured to measure the conductivity of the first process solution at a certain temperature, a calculation unit configured to determine a manganese concentration based on the conductivity of the first treatment solution at the temperature and a correlation between the conductivity and the concentration, a persulfate feed pump configured to add persulfate according to the determined manganese concentration to produce a second treatment solution and to precipitate at least a portion of the manganese oxide, and - a filter configured to filter the manganese oxide.

[0041] The device is able to determine the manganese concentration and thus the persulfate dosage required to precipitate the manganese as manganese oxide. Thanks to the determination performed by a simple and low-cost conductivity measuring device and a calculation unit, the device is able to track the process online without the need for expensive analytical equipment or downtime. In addition, the device ensures, with the help of the conductivity measuring device and the calculation unit, that the manganese is completely precipitated before releasing the treatment solution for the subsequent stages of the treatment method. The device thus optimizes reaction times, reduces the risk of off-spec products and reduces operating expenses by optimizing reagent quantities. Likewise, capital expenditures are reduced due to low-cost equipment and software instead of other expensive online analytical methods such as XRF or ICP-OES.

[0042] The reactor may include, for example, heating equipment and mixing means for producing the first process solution.

[0043] Furthermore, the reactor may include a valve for releasing the process solution to the next step.

[0044] The conductivity measuring device is configured to measure the conductivity of the first process solution. The conductivity measuring device may be, for example, a conductivity electrode.

[0045] The conductivity measuring device may include a computing unit capable of determining the manganese concentration based on the conductivity of the first treatment solution, or may include a transmitter configured to transmit information to an external device for processing. The device may also include a computing unit and a transmitter. The device may also include a processing unit for controlling the various components of the device, but it does not perform the determination itself. If the device includes a computing unit configured to determine the manganese concentration based on the conductivity of the first treatment solution, it generally also includes or is connected to a database containing manganese concentration data at a given conductivity. In addition to or in lieu of the database, the computing unit may apply an equation or slope determined by the conductivity measurement to determine the manganese concentration at a given conductivity. Therefore, the determination of the manganese concentration is based on a comparison of the measured conductivity and the manganese concentration, where the conductivity is measured by the conductivity measuring device. Therefore, the device may also include or be connected to a database containing manganese concentration data at a given conductivity.

[0046] If the manganese concentration is determined on the apparatus itself based on the conductivity of the first process solution, it may still include a transmitter for transmitting the determination to an external location.

[0047] The computing unit may be configured to calculate the required amount of persulfate using the database and control the persulfate feed pump accordingly to feed persulfate into the first treatment solution to form the second treatment solution and precipitate at least a portion of the manganese oxide.

[0048] When the conductivity of the solution obtained after precipitation and filtration reaches a threshold value, the computing unit can be configured to issue a command to the valve of the reactor to release the treated solution to the next step. Thus, once the desired conductivity is reached, the treated solution can be released to the next step and the reactor can be filled with a new batch of manganese-containing material. Detailed description with drawings

[0049] Figure 1 A method for treating a manganese-containing material according to a first embodiment is shown. In step a), the manganese-containing material is leached 101 using sulfuric acid and hydrogen peroxide to produce a first treatment solution containing manganese sulfate, and the first treatment solution is filtered. In step b), the conductivity of the first treatment solution is measured 102. In step c), the manganese concentration is determined 103 based on the conductivity of the first treatment solution. In step d), persulfate is added 104 based on the determined manganese concentration to produce a second treatment solution, and at least a portion of the manganese oxide is precipitated. In step e), the manganese oxide is filtered 105.

[0050] Figure 2 A method for treating a manganese-containing material according to a second embodiment is shown. The method further comprises a step d') after step d), wherein steps b), c) and d) are repeated for a third treatment solution, wherein the third treatment solution is obtained after precipitation of the second treatment solution.

[0051] Figure 3 A method for treating a manganese-containing material according to a third embodiment is shown. The method further comprises a step f) for determining the manganese concentration of the solution obtained after precipitation and filtration using an analytical method. The method further comprises using the manganese concentration determined by the analytical method to improve the determination of the manganese concentration.

[0052] Figure 4 A method for treating a manganese-containing material according to a fourth embodiment is shown. The method further comprises a step g) for releasing the treated solution to the next step when the conductivity of the solution obtained after precipitation and filtration reaches a threshold value.

[0053] Figure 5 A treatment device for manganese-containing material is shown. The device includes a reactor 201, a conductivity measuring device 202, a computing unit 203, a persulfate feed pump 204, and a filter 205. The reactor 201 contains manganese-containing material, sulfuric acid, and hydrogen peroxide, and is used to produce a first treatment solution containing manganese sulfate. The conductivity measuring device 202 is connected to the reactor 201 for measuring the conductivity of the first treatment solution. The computing unit 203 is connected to the conductivity measuring device 202 for determining the manganese concentration according to the conductivity of the first treatment solution. The computing unit 203 is also connected to the persulfate feed pump 204 for adding persulfate according to the determined manganese concentration to produce a second treatment solution and precipitating at least a portion of manganese oxide. The conductivity measuring device 202 is connected to the filter 205 and is configured to control the filter 205 connected to the reactor 201. The filter 205 is configured to filter the manganese oxide. Example Example 1

[0054] A mixture of raw materials (black material and nickel dihydroxide) containing different amounts of manganese oxide was dissolved in a solution of sulfuric acid and hydrogen peroxide. The proportions of the different raw materials in the mixture were chosen so that the final total metal concentration in the solution was about 35-40 g / l. Solutions with different manganese contents were prepared. The solutions were filtered and analyzed for metal content using ICP-OES. The conductivity was measured at 80°C and 20°C and plotted against the manganese concentration, as shown in Figure 2. Figure 6 Using the data, we calculate the slope and intercept to get the following equation: At 20°C: [Mn] = (conductivity - 10.7009) / - 0.0008 At 80°C: [Mn] = (conductivity - 5.6416) / - 0.0004

[0055] This equation is then used to determine the manganese content in the example described below. When measuring conductivity and building a database, it is important to measure and record the temperature because increasing temperature decreases conductivity. Example 2

[0056] 10 grams of black material (total metal content of about 35%) (containing nickel, cobalt, manganese and lithium) was dissolved in 100 milliliters of 10 wt-% sulfuric acid (80°C), and then 4 wt-% hydrogen peroxide was added. One (1) hour after the addition of hydrogen peroxide, the mixture was filtered and the filtrate conductivity was measured to be 3.195 mS / cm. According to the database, the manganese content was calculated to be 10053 ppm. The metal content measured using ICP-OES was 10290 ppm. Therefore, the accuracy of the conductivity measurement was 97.7%.

[0057] The amount of persulfate required to precipitate all the manganese sulfate as manganese oxide was calculated to be 46 g (a molar ratio of 1:1.1). Four hours after the required amount of persulfate was added, the conductivity was measured to be 9.751 mS / cm, which according to the model indicated a Mn content of 0 ppm. To double-check the manganese content, the mixture was filtered and analyzed by ICP-OES to give a manganese concentration of 7 ppm and a manganese oxide yield of 99.9%.

[0058] It should be understood that the embodiments of the present invention disclosed are not limited to the specific structures, process steps or materials disclosed herein, but are extended to their equivalents recognized by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used to describe specific embodiments and are not intended to be limiting.

[0059] Furthermore, the described features, structures or characteristics may be combined in any suitable manner in one or more embodiments.In the description, many specific details are provided, such as examples of length, width, shape, etc., to provide a thorough understanding of the embodiments of the present invention.

[0060] The verbs "to comprise" and "to include" are used in this document as open limitations, neither excluding nor requiring the presence of unrecited features. Unless expressly stated otherwise, the features recited in the dependent claims may be freely combined with each other. Furthermore, it should be understood that the use of "a" or "an" in this document, i.e. the singular, does not exclude a plural form.

Claims

1. A method for treating a manganese-containing material, comprising: a) leaching a manganese-containing material using sulphuric acid and hydrogen peroxide to produce a first process solution comprising manganese sulphate, filtering the first process solution, b) measuring the conductivity of the first process solution at a certain temperature, c) determining a manganese concentration based on said conductivity of the first process solution measured at said temperature and a correlation between said conductivity and concentration, d) adding persulfate based on the determined manganese concentration to produce a second treatment solution and precipitating at least a portion of the manganese oxide, and e) filtering the manganese oxide to produce a manganese-depleted treatment solution.

2. The method according to claim 1, wherein: The conductivity of the first treatment solution is measured at a temperature of 15-90°C, preferably 70-90°C, more preferably 75-85°C.

3. A method as claimed in any one of the preceding claims, wherein: Step d) further comprises heating the first treatment solution to a temperature of 70-90°C, preferably 75-85°C, before adding the persulfate.

4. A method as claimed in any one of the preceding claims, wherein: The molar ratio of the persulfate to manganese sulfate is 0.95-1.3:1, preferably 1-1.1:

1.

5. A method as claimed in any one of the preceding claims, wherein: The persulfate is a monoprotic persulfate.

6. A method as claimed in any one of the preceding claims, wherein: The persulfate is sodium persulfate, ammonium persulfate, potassium persulfate or lithium persulfate.

7. The method according to any one of the preceding claims, further comprising a step d') after step d), wherein: Steps b), c) and d) are repeated for a third treatment solution, wherein the third treatment solution is obtained after precipitation of the second treatment solution.

8. The method according to any one of the preceding claims, further comprising a step f) for determining the manganese concentration of the solution obtained after precipitation and filtration by analytical methods.

9. The method of claim 8, further comprising improving the determination of manganese concentration using the manganese concentration determined by an on-line analytical method.

10. The method according to any one of the preceding claims, further comprising a step g) for releasing the treated solution to the next step when the conductivity of the solution obtained after precipitation and filtration reaches a threshold value.

11. The method of claim 10, wherein: The threshold value is higher than 9.5 mS / cm, preferably 9.5-12 mS / cm, more preferably 9.5-11 mS / cm.

12. A device for processing manganese-containing materials, the device comprising: - a reactor for containing a manganese-containing material, sulfuric acid and hydrogen peroxide, configured to produce a first treatment solution comprising manganese sulfate, - a conductivity measuring device configured to measure the conductivity of said first process solution at a certain temperature, a calculation unit configured to determine a manganese concentration based on said conductivity of said first treatment solution at said temperature and a correlation between said conductivity and concentration, a persulfate feed pump configured to add persulfate according to the determined manganese concentration to produce a second treatment solution and to precipitate at least a portion of the manganese oxide, and - a filter configured to filter the manganese oxide.

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