Method for efficiently recovering copper, antimony and rare and precious metals from copper anode slime

Abstract

The present application relates to copper anode slime leaching technical field, specifically to a kind of copper anode slime copper, antimony and rare and precious metal high-efficiency recovery method, including according to batch to mixed equipment input quantitative copper anode slime and deionized water, and slurry is prepared according to certain liquid-solid mass ratio, and uniform suspension slurry is obtained;Sulfuric acid and sodium chloride are added to the uniform suspension slurry, heated to preset temperature, and reacted for a certain time to obtain reaction material;The reaction material is filtered and washed, and sodium hydroxide is added to the filtrate to separate and recover antimony and bismuth, the filter residue is dried and weighed, and the content of each element is analyzed, the method first prepares copper anode slime suspension, and by adjusting the content of added sulfuric acid, sodium chloride and sodium hydroxide, the pH value is adjusted, and then antimony and bismuth are precipitated respectively, the leaching rate of antimony and bismuth reaches 71% and 90% respectively, solves the problem that the existing method for recovering antimony and bismuth from copper-depleted anode slime cannot achieve satisfactory leaching effect.

Description

Technical Field

[0001] This invention relates to the field of copper anode mud leaching technology, and in particular to a method for the efficient recovery of copper, antimony and rare precious metals from copper anode mud. Background Technology

[0002] Copper anode sludge is a byproduct of copper electrolytic refining. During the electrolytic refining of copper, various valuable metals insoluble in the electrolyte are enriched in the copper anode sludge. The composition of the anode sludge is complex, containing gold, silver, copper, lead, selenium, tellurium, antimony, bismuth, arsenic, and platinum group metals. Because the electrode potentials of antimony and bismuth are close to those of copper, they are difficult to deposit at the cathode during copper electrolytic refining. However, as the anode copper dissolves during electrolysis, these elements dissolve and enter the electrolyte. Most react to form corresponding salts, which eventually settle to the bottom of the tank and become anode sludge. The remaining portion accumulates in the electrolyte, causing a continuous increase in the impurity content. The antimony and bismuth that enter the copper anode sludge are usually tightly bound, generally existing in the form of oxides or arsenates. Antimony and bismuth are further enriched in the pre-treatment copper removal slag, from which antimony and bismuth can be recovered.

[0003] There are two main methods for recovering antimony and bismuth from anode mud after copper removal: pyrometallurgical processes and hydrometallurgical processes. While the pyrometallurgical process for recovering antimony and bismuth from anode mud is simple to operate, the separation of antimony and bismuth is relatively difficult, and vacuum distillation is sometimes used to recover them. Hydrometallurgical processes are currently the focus of research, and are divided into alkaline and acidic systems depending on the leaching process. Alkaline systems mainly use sodium hydroxide; acidic systems have been extensively studied using hydrochloric acid or hydrochloric acid + sulfuric acid + sodium chloride, and are already being used in some production processes. Some literature indicates that using a single acid system of sulfuric acid + sodium chloride results in excessively high chloride ion concentrations, leading to a large amount of metal entering the solution, especially precious metals, which are easily leached. The leaching rates for gold and silver exceeded 1% and 2%, respectively, failing to achieve satisfactory leaching results. Summary of the Invention

[0004] The purpose of this invention is to provide a highly efficient method for recovering copper, antimony, and rare and precious metals from copper anode mud, aiming to solve the problem that existing methods for recovering antimony and bismuth from copper-removed anode mud cannot achieve satisfactory leaching results.

[0005] To achieve the above objectives, the present invention provides a method for efficient recovery of copper, antimony and rare and precious metals from copper anode mud, comprising the following steps; A fixed amount of copper anode mud and deionized water are added to the mixing equipment in batches, and the mixture is adjusted according to a certain liquid-solid mass ratio to obtain a uniform suspension slurry. Sulfuric acid and sodium chloride are added to the homogeneous suspension slurry, and the mixture is heated to a preset temperature and reacted for a certain period of time to obtain the reaction material. The reactants were filtered and washed, and sodium hydroxide was added to the filtrate to separate and recover antimony and bismuth. The filter residue was dried, weighed, and the content of each element was analyzed.

[0006] The specific method for adding quantitative copper anode mud and deionized water to the mixing equipment in batches and adjusting the slurry according to a certain liquid-solid mass ratio to obtain copper anode mud slurry is as follows: Dry and uniformly sized copper anode mud was selected and reduced to the required amount for the experiment using the quartering method to obtain a quantitative amount of copper anode mud. A fixed amount of copper anode mud and calculated deionized water are added to the mixing equipment in batches, and the mixture is adjusted according to a certain liquid-solid mass ratio to form a uniform suspension slurry.

[0007] The specific method for adding sulfuric acid and sodium chloride to the uniform suspension slurry, heating to a preset temperature, and reacting for a certain period of time to obtain the reactants is as follows: Keep the mixing equipment stirring, and slowly add concentrated sulfuric acid and sodium chloride solid to the uniform suspension slurry; Set the temperature of the constant temperature water bath to the preset reaction temperature, react for a certain period of time, and obtain the reaction materials.

[0008] During the process of slowly adding concentrated sulfuric acid and adding solid sodium chloride, it is necessary to sample and test the mass fraction of sulfuric acid and the concentration of chloride ions in the slurry.

[0009] The specific method for filtering and washing the reaction materials, adding sodium hydroxide to the filtrate to separate and recover antimony and bismuth, drying the filter residue, weighing it, and analyzing the content of each element is as follows: The reactants are filtered to separate the solid and liquid components into a filtrate. Add 10% sodium hydroxide solution to the filtrate at room temperature to adjust to a certain pH value, filter, and obtain antimony slag. Add 10% sodium hydroxide solution to the filtrate to adjust to a certain pH value, filter, and obtain bismuth slag. The filter paper with the filter cake was transferred to a porcelain crucible and dried in a forced-air drying oven to obtain the filter residue. Weigh a quantitative amount of the filter residue, digest it, and dilute it to volume with deionized water to obtain the test solution; The content of each element in the test solution was determined and analyzed.

[0010] The specific method for filtering the reactants and separating the solid-liquid filtrate is as follows: The reactants are transferred to a Buchner funnel pre-lined with filter paper for filtration. Gently scrape the filter cake with a scraper, add deionized water at the reaction temperature to the Buchner funnel, wash repeatedly, filter, and obtain the filtrate.

[0011] This invention discloses a method for the efficient recovery of copper, antimony, and rare precious metals from copper anode mud. The method involves batch-wise feeding of quantitative copper anode mud and deionized water into a mixing device, adjusting the mixture according to a specific liquid-to-solid mass ratio to obtain a uniform suspension slurry. Sulfuric acid and sodium chloride are added to the uniform suspension slurry, and the mixture is heated to a preset temperature and reacted for a certain time to obtain reactant material. The reactant material is then filtered and washed, and sodium hydroxide is added to the filtrate to separate and recover antimony and bismuth. The filter residue is dried, weighed, and the content of each element is analyzed. This method first prepares a copper anode mud suspension, and by adjusting the content of added sulfuric acid, sodium chloride, and sodium hydroxide, its pH value is adjusted, thereby precipitating antimony and bismuth separately. The leaching rates of antimony and bismuth reach 71% and 90%, respectively, solving the problem that existing methods for recovering antimony and bismuth from copper anode mud cannot achieve satisfactory leaching results. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This invention provides a process for the efficient recovery of copper, antimony, and rare and precious metals from copper anode mud.

[0014] Figure 2 This is a flowchart of a method for efficient recovery of copper, antimony, and rare and precious metals from copper anode mud provided by the present invention.

[0015] Figure 3 This is a flowchart illustrating the specific process of adding quantitative amounts of copper anode mud and deionized water to a mixing device in batches and adjusting the mixture according to a certain liquid-solid mass ratio to obtain copper anode mud slurry.

[0016] Figure 4 This is a flowchart illustrating the specific method of adding sulfuric acid and sodium chloride to the homogeneous suspension slurry, heating it to a preset temperature, and reacting it for a certain period of time to obtain the reactant material.

[0017] Figure 5 The flowchart describes a specific method for filtering and washing the reaction materials, adding sodium hydroxide to the filtrate to separate and recover antimony and bismuth, drying the filter residue, weighing it, and analyzing the content of each element. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] Please see Figures 1 to 5 This invention provides a method for efficient recovery of copper, antimony and rare precious metals from copper anode mud, comprising the following steps; S1 feeds a quantitative amount of copper anode mud and deionized water into the mixing equipment in batches, and adjusts the slurry according to a certain liquid-solid mass ratio to obtain a uniform suspension slurry. Specific methods: S11 Select dry and uniformly sized copper anode mud, and reduce it to the required amount for the experiment using the quartering method to obtain a quantitative amount of copper anode mud; In this embodiment of the invention, dry copper anode mud with uniform particle size is selected and reduced to the required amount for the experiment using the quartering method. The amount added in each batch must be accurately weighed (the recommended accuracy is 0.001g).

[0020] S12 feeds a quantitative amount of copper anode mud and calculated deionized water into the mixing equipment in batches, and adjusts the slurry according to a certain liquid-solid mass ratio to form a uniform suspension slurry.

[0021] In this embodiment of the invention, a calculated amount of deionized water (recorded volume V of water) is added to the mixing device, which is then placed on a constant temperature water bath support. A stirring paddle (1-2 cm from the bottom of the container), a thermometer (inserted to a depth ≥3 cm into the liquid), and a condenser (if necessary to prevent water evaporation) are installed. The stirring is turned on (speed controlled at 200-300 r / min to ensure uniform slurry), and the weighed copper anode mud (m1) is slowly added. Stirring continues for 10-15 minutes to form a uniform suspension slurry. At this point, the liquid-to-solid mass ratio must meet a preset value (this can be fine-tuned by adding water or anode mud).

[0022] S2 adds sulfuric acid and sodium chloride to the uniform suspension slurry, heats it to a preset temperature, and reacts it for a certain period of time to obtain the reaction material; Specific methods: S21 Keep the mixing equipment stirring and slowly add concentrated sulfuric acid and sodium chloride solid to the uniform suspension slurry; In this embodiment of the invention, while maintaining stirring, the calculated amount of concentrated sulfuric acid is slowly added dropwise (the dropping rate is controlled at 1-2 mL / min to avoid local overheating and splashing of the slurry). After the addition is completed, stirring is continued for 20 minutes to ensure uniform dispersion of the sulfuric acid. At this point, the mass fraction of sulfuric acid in the slurry is detected by sampling (acid-base titration can be used: take 1 mL of slurry, dilute it to 100 mL, and titrate it with 0.1 mol / L sodium hydroxide standard solution until phenolphthalein changes color, and calculate the sulfuric acid concentration). If the target value is not reached, a small amount of concentrated sulfuric acid is added until the requirement is met (record the actual total amount of sulfuric acid used, m = sulfuric acid). Add the weighed sodium chloride solid (m sodium chloride) to the slurry and stir for 30 minutes until completely dissolved. Take a sample to test the chloride ion concentration (using the silver nitrate titration method: take 1 mL of slurry, dilute to 100 mL, add 5% potassium chromate indicator, and titrate with 0.1 mol / L silver nitrate standard solution until a brick-red precipitate is formed, and calculate the chloride ion concentration). If the concentration is too low, add sodium chloride solid to the preset value (record the actual total amount of sodium chloride used, m total sodium chloride).

[0023] S22 sets the temperature of the constant temperature water bath to the preset reaction temperature, reacts for a certain time, and obtains the reaction material.

[0024] In this embodiment of the invention, the temperature of the constant temperature water bath is set to the preset reaction temperature (e.g., 60-90℃), the heating switch is turned on, and the temperature is slowly increased at a rate of 5-10℃ / h to avoid excessively rapid heating that could lead to violent local reactions.

[0025] S3 Filter and wash the reaction materials, and add sodium hydroxide to the filtrate to separate and recover antimony and bismuth. The filter residue is dried, weighed, and the content of each element is analyzed.

[0026] Specific methods: S31 Filter the reaction materials to separate the solid and liquid components into filtrate; Specific methods: S311 The reactants are transferred to a Buchner funnel with pre-laid filter paper for filtration. In this embodiment of the invention, the reactants are transferred to a Buchner funnel pre-laid with filter paper (dried to constant weight at 105°C, and the mass of the filter paper is recorded as m) for filtration. A vacuum pump is connected for filtration, and the vacuum level is kept stable (0.06-0.08 MPa) during the filtration process. S312 uses a scraper to gently level the filter cake, and adds deionized water at the reaction temperature to the Buchner funnel. After repeated washing and filtration, the filtrate is obtained.

[0027] In this embodiment of the invention, after the slurry has been basically dried, the filter cake is gently scraped flat with a scraper to prevent it from breaking and causing leakage. The start time of filtration is recorded to ensure that filtration is completed within 1 hour (if the filtration rate is too slow, the vacuum level can be reduced or the filter paper can be replaced). Deionized water at 60-70°C (close to the reaction temperature to avoid the filter cake shrinking due to cold and affecting the washing effect) is slowly added to the Buchner funnel. The amount of water should be enough to cover the filter cake. After soaking for 5 minutes, filtration is started. The washing is repeated 3-5 times. After each washing, a small amount of filtrate is taken and tested with silver nitrate solution (no white precipitate is formed after adding the solution, indicating that chloride ions have been washed away). After the last washing, filtration continues for 30 minutes to remove as much water as possible from the filter cake. The total mass of the filter cake and filter paper, m_total, is recorded (it needs to be weighed again after drying).

[0028] S32 Add 10% sodium hydroxide solution to the filtrate at room temperature to adjust to a certain pH value, filter, and obtain antimony slag. Continue to add 10% sodium hydroxide solution to the filtrate to adjust to a certain pH value, filter, and obtain bismuth slag. S33 Transfer the filter paper with the filter cake to a porcelain crucible, place it in a forced-air drying oven to dry, and obtain filter residue; In this embodiment of the invention, the filter paper containing the filter cake is transferred to a numbered porcelain crucible (the porcelain crucible has been dried to constant weight at 105°C, and its mass is recorded as m_crucible), placed in a forced-air drying oven, and dried at 105°C for 4-6 hours (adjusted according to the thickness of the filter cake). Every hour, the porcelain crucible is removed and placed in a desiccator to cool to room temperature (approximately 30 minutes). The mass is measured using an electronic balance until the difference between two weighings is ≤0.002g, which is considered constant weight. The total mass at this point is recorded as m_crucible + filter cake + filter paper. The mass of the filter residue is calculated as: m_residue = m_crucible + filter cake + filter paper - m_crucible - m_filter paper.

[0029] S34 Weigh a quantitative amount of the filter residue, digest it, and dilute it to volume with deionized water to obtain the test solution; In this embodiment of the invention, 0.1-0.2 g of dried filter residue (accurate to 0.0001 g, denoted as m analytical sample) is weighed and placed in a polytetrafluoroethylene digestion vessel. 5 mL of nitric acid (1:1), 2 mL of hydrofluoric acid, and 1 mL of perchloric acid are added. After capping, the vessel is placed in a microwave digester and digested according to a preset program (e.g., heating to 180°C and holding for 20 min). After digestion, the vessel is cooled to room temperature and transferred to a 50 mL volumetric flask. The volume is adjusted to the mark with deionized water and shaken well to obtain the test solution (if there is precipitation, it needs to be filtered again).

[0030] S35 determines and analyzes the content of each element in the test solution.

[0031] In this embodiment of the invention, the concentrations (unit: mg / L) of target elements such as copper, antimony, bismuth, gold, and silver in the test solution are determined using ICP-OES or AAS. Calibration (using standard solutions to plot standard curves) and detection are performed according to the instrument's operating instructions. The leaching rate of each element is calculated as follows: n = [(m0 *n0 - m1 *n1) / (m0 * n0)] × 100%, where: m0 is the mass of the copper-removing mud (g); m1 is the mass of the leaching residue (g); n0 is the mass fraction of the element in the copper-removing mud (%); and n1 is the mass fraction of the element in the leaching residue (%).

[0032] To better understand this technical solution, the following embodiments are provided for further explanation: I. Effect of liquid-to-solid mass ratio on antimony and bismuth leaching rates Different liquid-to-solid mass ratios were used to prepare the slurry. The reaction temperature was controlled at 70℃, the sulfuric acid concentration in the solution was adjusted to 80 g / L, and sodium chloride was added to control the chloride ion concentration at 100 g / L. The reaction time was 2 hours. The experiment showed that the leaching rates of antimony and bismuth increased with increasing liquid-to-solid mass ratio. This is because a higher liquid-to-solid mass ratio reduces the viscosity of the reaction system, improving diffusion conditions. Furthermore, the total amount of reagents added increases, leading to a more positive reaction and a more complete reaction. However, an excessively high liquid-to-solid mass ratio not only increases the total amount of reactants but also increases power and reagent consumption, requiring larger reaction equipment and increasing overall processing costs. Considering all factors, a liquid-to-solid mass ratio of 4:1 is more suitable, at which the leaching rates of antimony and bismuth reached 71% and 90%, respectively.

[0033] II. Effect of Solution Acidity on Antimony and Bismuth Leaching Rates The reaction was conducted with a liquid-to-solid mass ratio of 4:1, a reaction temperature of 70℃, and varying sulfuric acid concentrations. Sodium chloride was added to maintain a chloride ion concentration of 100 g / L, and the reaction time was 2 hours. When the sulfuric acid concentration in the reaction system was too low, the leaching rates of antimony and bismuth were both low. This is because Sb³* and Bi³* in the leachate require a relatively high acidity to stably combine with Cl- to form stable SbCl3 and BiCl3. If the acidity is insufficient (solution pH not less than 0.5), the remaining H+ in the system is insufficient during the reaction, causing some SbCl3 and BiCl3 to hydrolyze to form SbOC1 and BiOC1, thus reducing the leaching rate. As the concentration of sulfuric acid in the reaction system increases, the leaching rates of antimony and bismuth increase significantly. When the sulfuric acid concentration reaches 120 g / L, the leaching rates of antimony and bismuth increase to 82.5% and 91.9%, respectively. Further increases in solution acidity do not significantly improve the leaching rates of antimony and bismuth, and excessively high acidity will increase the amount of alkali required for subsequent neutralization treatment to recover antimony and bismuth, thus increasing processing costs. Therefore, a sulfuric acid concentration of 120 g / L is more suitable.

[0034] III. Effect of Chloride Ion Concentration on Antimony and Bismuth Leaching Rates The reaction was conducted with a liquid-to-solid mass ratio of 4:1, a reaction temperature of 70℃, and a sulfuric acid concentration of 120 g / L. Sodium chloride was added to adjust the chloride ion concentration at different levels, and the reaction time was 2 hours. The leaching rates of antimony and bismuth increased with increasing chloride ion concentration. This is because increasing chloride ion concentration shifts the reaction towards the forward direction, further increasing the formation of SbCl and BiCl in the solution. Increasing chloride ion concentration also expands the stable existence regions of SbCl and BiCl. Furthermore, since the copper removal slag contains a significant amount of lead, other forms of antimony and bismuth encapsulated in the material particles further participate in the reaction during the conversion of lead sulfate to lead chloride, increasing the leaching rates of antimony and bismuth. Further increasing the chloride ion concentration leads to an increase in the leaching rates of other elements, especially lead. The leaching solution exhibits a large amount of lead chloride crystallization as the temperature decreases, which is detrimental to solid-liquid separation in production. Continuing to increase the chloride ion concentration increases the probability of the reaction occurring after completion. Therefore, considering all factors, a chloride ion concentration of 140 g / L is deemed most suitable.

[0035] IV. Effect of reaction temperature on antimony and bismuth leaching rates A liquid-to-solid mass ratio of 4:1 was used in the reaction. Different reaction temperatures were controlled, the sulfuric acid concentration was adjusted to 120 g / L, and sodium chloride was added to control the chloride ion concentration at 140 g / L. The reaction time was 2 hours. Reaction temperature significantly affected the leaching rates of antimony and bismuth. Lower reaction temperatures resulted in lower leaching rates for both antimony and bismuth. At temperatures above 80℃, the leaching rates reached 85.9% and 97.8%, respectively. Further increases in reaction temperature did not significantly improve the leaching rates. This is because, in actual leaching processes, temperature affects both the chemical reaction rate and the diffusion rate. Higher temperatures enhance the ability to break or weaken chemical bonds, increase the number of activated molecules, and accelerate the leaching rate. Simultaneously, higher temperatures also accelerate the diffusion rate. In this experiment, increasing the temperature primarily improved the chemical reaction rate. However, excessively high reaction temperatures can lead to increased costs, chloride ion volatilization, deterioration of the reaction environment, and accelerated corrosion of reaction equipment. Therefore, considering all factors, a reaction temperature of 80℃ was deemed most suitable.

[0036] The above-disclosed embodiments are merely preferred embodiments of the efficient recovery method of copper, antimony, and rare and precious metals from copper anode mud according to the present invention. Of course, they should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for efficient recovery of copper, antimony, and rare and precious metals from copper anode mud, characterized in that, Includes the following steps; A fixed amount of copper anode mud and deionized water are added to the mixing equipment in batches, and the mixture is adjusted according to a certain liquid-solid mass ratio to obtain a uniform suspension slurry. Sulfuric acid and sodium chloride are added to the homogeneous suspension slurry, and the mixture is heated to a preset temperature and reacted for a certain period of time to obtain the reaction material. The reactants were filtered and washed, and sodium hydroxide was added to the filtrate to separate and recover antimony and bismuth. The filter residue was dried, weighed, and the content of each element was analyzed.

2. The method for efficient recovery of copper, antimony, and rare and precious metals from copper anode mud as described in claim 1, characterized in that... ； The specific method for adding quantitative copper anode mud and deionized water to the mixing equipment in batches and adjusting the slurry according to a certain liquid-solid mass ratio to obtain copper anode mud slurry is as follows: Dry and uniformly sized copper anode mud was selected and reduced to the required amount for the experiment using the quartering method to obtain a quantitative amount of copper anode mud. A fixed amount of copper anode mud and calculated deionized water are added to the mixing equipment in batches, and the mixture is adjusted according to a certain liquid-solid mass ratio to form a uniform suspension slurry.

3. The method for efficient recovery of copper, antimony, and rare and precious metals from copper anode mud as described in claim 1, characterized in that... ； The specific method for adding sulfuric acid and sodium chloride to the homogeneous suspension slurry, heating to a preset temperature, and reacting for a certain period of time to obtain the reactants is as follows: Keep the mixing equipment stirring, and slowly add concentrated sulfuric acid and sodium chloride solid to the uniform suspension slurry; Set the temperature of the constant temperature water bath to the preset reaction temperature, react for a certain period of time, and obtain the reaction materials.

4. The method for efficient recovery of copper, antimony, and rare and precious metals from copper anode mud as described in claim 3, characterized in that; During the slow dripping of concentrated sulfuric acid and the addition of sodium chloride solid, it is necessary to sample and test the mass fraction of sulfuric acid and the concentration of chloride ions in the slurry.

5. The efficient recovery method for copper, antimony, and rare and precious metals from copper anode mud as described in claim 1. Its characteristics are: The specific method for filtering and washing the reaction materials, adding sodium hydroxide to the filtrate to separate and recover antimony and bismuth, drying the filter residue, weighing it, and analyzing the content of each element is as follows: The reactants are filtered to separate the solid and liquid components into a filtrate. Add 10% sodium hydroxide solution to the filtrate at room temperature to adjust to a certain pH value, filter, and obtain antimony slag. Add 10% sodium hydroxide solution to the filtrate to adjust to a certain pH value, filter, and obtain bismuth slag. The filter paper with the filter cake was transferred to a porcelain crucible and dried in a forced-air drying oven to obtain the filter residue. Weigh a quantitative amount of the filter residue, digest it, and dilute it to volume with deionized water to obtain the test solution; The content of each element in the test solution was determined and analyzed.

6. The efficient recovery method for copper, antimony, and rare and precious metals from copper anode mud as described in claim 5. Its characteristics are: The specific method for filtering the reactants and separating the solid-liquid filtrate is as follows: The reactants are transferred to a Buchner funnel pre-lined with filter paper for filtration. Gently scrape the filter cake with a scraper, add deionized water at the reaction temperature to the Buchner funnel, wash repeatedly, filter, and obtain the filtrate.

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