Method for judging oxidation impurity removal reaction endpoint

Abstract

The invention provides a method for judging an oxidation impurity removal reaction endpoint. The method comprises the following steps: S1, carrying out oxidation impurity removal on a solution to be subjected to impurity removal containing impurity metal ions by adopting an oxidizing agent, and meanwhile, adding a neutralizing agent to carry out a neutralization reaction, so as to obtain a reaction system; and step S2, starting to add an oxidizing agent into the solution to be subjected to impurity removal as a timing starting point, detecting the consumption amount of the neutralizing agent in a fixed time interval, recording the result of the first detection as the initial consumption amount of the neutralizing agent until the ratio of the final consumption amount to the initial consumption amount of the neutralizing agent is less than or equal to 0.55: 1, and taking the result as a reaction endpoint of oxidation impurity removal, an impurity-removed solution is obtained; wherein the pH value of oxidation impurity removal is 4.5-5; the mass concentration of impurity metal ions in the solution after impurity removal is less than 1mg / L. According to the method, the oxidation impurity removal effect can be guaranteed, the process cost can be effectively reduced, and therefore good economic benefits are obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of oxidation and impurity removal reactions, and in particular to a method for determining an end point of an oxidation and impurity removal reaction. Background Art

[0002] The oxidation precipitation process is an effective impurity removal method in the current hydrometallurgical process. It utilizes the characteristic that high-valent metal ions have a lower pH value when they precipitate to oxidize low-valent metal ions into high-valent metal ions, thereby achieving the purpose of removing impurity ions.

[0003] Oxidants are commonly used in oxidation precipitation processes. Common solid oxidants, such as KMnO4 and Na2S2O8, can easily introduce other impurity ions while performing their oxidation, resulting in suboptimal performance. Gaseous oxidants, including O2, O3, and mixed SO2 and O2 gases, can effectively avoid the introduction of impurity ions. However, these gaseous oxidants generate acid during use, necessitating the addition of a neutralizer to stabilize the pH within a certain range. For this reason, the amount of neutralizer used has become a key economic indicator for oxidation precipitation processes.

[0004] The Chinese patent application with the patent application publication number CN116445728A provides a method for removing Cu-containing 2+ Mn in leachate 2+ method, and SO2 / O2 oxidizes Mn 2+ The generated acid is used to leach Cu from copper oxides 2+ , to obtain higher Mn 2+ removal rate and free acid utilization rate. Although this method can achieve solution pH control, it can also 2+ Leaching into the solution achieves effective utilization of acid, but in order to ensure that Cu 2 + To achieve the best leaching effect, the pH value of the system needs to be controlled in a lower range (pH value is 1-2), so, except for Mn 2+ The effect of Mn removal still has room for improvement, and it takes a long time to remove Mn. 2+ Mn in the post-liquid 2+ The mass concentration is relatively high (0.25g / L).

[0005] The Chinese patent application with the patent publication number CN116732326A provides a method for enriching and recovering Mn from a cobalt-containing low-copper raffinate, using calcium oxide, calcium carbonate, calcium hydroxide or activated magnesium oxide as a neutralizer, first controlling the pH value to 1.5-5.5 and using SO2 / O2 to oxidize Fe 2+ Then control the pH value to 2.5-5.5 and the potential to >800mV to make Mn2+ Oxidation precipitation into slag, the manganese slag as a secondary resource to recover Mn. This method provides a process for the resource of impurity element Mn, but its manganese removal time is long and the Mn removal 2+ Post-Mn 2+ The mass concentration is relatively high (0.15g / L), and neither the neutralizer utilization rate nor the manganese removal effect has reached the ideal level.

[0006] Current oxidation precipitation processes lack a clear definition of the extent of the oxidation-removal reaction, leading to high neutralizer usage, waste, and poor economic efficiency. Online monitoring of elemental content as the endpoint for SO₂ / O₂ removal is difficult to sustain in continuous production due to the large number of impurities and the dense sampling nodes. Therefore, a method for determining the extent of the oxidation-removal reaction is urgently needed. Summary of the Invention

[0007] The main purpose of the present invention is to provide a method for determining the end point of the oxidation and impurity removal reaction, so as to solve the problem in the prior art that the degree of the oxidation and impurity removal reaction is difficult to determine, resulting in a large amount of neutralizer used and poor overall process economy.

[0008] To achieve the above-mentioned object, according to one aspect of the present invention, a method for determining the endpoint of an oxidation and impurity removal reaction is provided, the method comprising: step S1, performing oxidation and impurity removal on a solution to be removed containing impurity metal ions using an oxidant, and simultaneously adding a neutralizer for neutralization reaction to obtain a reaction system; and step S2, taking the start of the addition of the oxidant to the solution to be removed as a timing starting point, detecting the consumption of the neutralizer within a fixed time interval, and recording the result of the first detection as the initial consumption of the neutralizer, until the ratio of the final consumption of the neutralizer to the initial consumption is ≤0.55:1, which is used as the endpoint of the oxidation and impurity removal reaction to obtain a solution after impurity removal; wherein the pH value of the oxidation and impurity removal is 4.5-5; and the mass concentration of the impurity metal ions in the solution after impurity removal is less than 1 mg / L.

[0009] Furthermore, the oxidant is selected from any one or more of a mixed gas of SO2 gas and O2 gas, and flue gas.

[0010] Furthermore, the oxidant is a mixed gas of SO2 gas and O2 gas, and the volume ratio of SO2 gas to O2 gas is ≤0.5.

[0011] Furthermore, the volume ratio of the oxidant to the solution to be removed is 0.2-1.16:1.5.

[0012] Furthermore, the total initial mass concentration of the impurity metal ions in the solution to be removed is ≥5 g / L, and / or the impurity metal ions in the solution to be removed are selected from Mn 2+ ions, Fe2+ ions, Fe 3+ ions and Cu 2+ Any one or more ions.

[0013] Furthermore, the oxidation and impurity removal is carried out under stirring conditions, with a stirring speed of 1000-1500 r / min; and / or the temperature of the oxidation and impurity removal is 20-25° C., and / or the time of the oxidation and impurity removal is 1.5-4 h.

[0014] Furthermore, the fixed time interval is determined according to the total initial mass concentration of the impurity metal ions in the solution to be removed, and preferably the fixed time interval is 30 to 60 minutes.

[0015] Furthermore, the neutralizing agent is selected from any one or more of 10-20 wt% MgO slurry, 10-20 wt% CaO slurry, NaOH and Ca(OH)2.

[0016] Furthermore, the consumption of the neutralizer is the mass difference of the reaction system within each fixed time interval.

[0017] Furthermore, the ratio of the final consumption to the initial consumption is 0.4-0.55:1.

[0018] Application of the technical scheme of the present invention, the application is judged by the consumption of neutralizer to remove the valence-varying impurity metal ion, i.e., the degree of progress of oxidation and impurity removal reaction, guide the time of impurity removal, so that the utilization of neutralizer is more efficient, and then reduce the cost of oxidation and impurity removal process. Specifically, due to the significant weakening of its reaction degree in the oxidation and impurity removal reaction later stage, and acid generation reaction is dominant, causing the consumption of neutralizer to increase and waste, therefore, the application is by detecting the consumption of neutralizer in fixed time intervals, controlling the final consumption of neutralizer and the ratio of initial consumption in the above-mentioned range, it is possible to effectively reduce the additional consumption of neutralizer in the oxidation and impurity removal reaction later stage. The pH value of the preferred control oxidation and impurity removal is in the above-mentioned range, it is possible to ensure the effective precipitation of foreign metal ions, while reducing the loss of valuable metals, thereby improving its rate of recovery, simultaneously, it is also possible to further improve the use efficiency of neutralizer, prevent the acid generated due to oxidation reaction of oxidant from causing pH value too low, thereby ensuring the continuing of oxidation and impurity removal reaction, avoid the waste of overacidification and neutralizer. Furthermore, the determination method of the present application can not only ensure the effectiveness of oxidation removal, ensuring that the mass concentration of impurity metal ions in the solution after removal reaches the above range, but also effectively reduce process costs, thereby achieving good economic benefits. This method has good applicability to dynamically changing production processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It shows that Mn in Example 1 of this application 2+ Graph showing changes in ion mass concentration and neutralizer consumption;

[0021] Figure 2 It shows that Mn in Example 2 of this application 2+ Graph showing changes in ion mass concentration and neutralizer consumption;

[0022] Figure 3 It shows that Mn in Comparative Example 1 of this application 2+ Graph showing changes in ion mass concentration and neutralizer consumption;

[0023] Figure 4 It shows that Mn in Comparative Example 2 of this application 2+ Graph showing changes in ion mass concentration and neutralizer consumption. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0025] As analyzed in the background technology of this application, the existing oxidation precipitation process has the problem that the degree of oxidation and impurity removal reaction is difficult to determine, resulting in a large amount of neutralizer used and poor overall process economy. In order to solve the above problems, this application provides a method for determining the end point of the oxidation and impurity removal reaction.

[0026] In a typical embodiment of the present application, a method for determining the endpoint of an oxidation and impurity removal reaction is provided, the method comprising: step S1, performing oxidation and impurity removal on a solution to be removed containing impurity metal ions using an oxidant, and simultaneously adding a neutralizer for a neutralization reaction to obtain a reaction system; and step S2, taking the start of the addition of the oxidant to the solution to be removed as a timing starting point, detecting the consumption of the neutralizer within a fixed time interval, and recording the result of the first detection as the initial consumption of the neutralizer, until the ratio of the final consumption of the neutralizer to the initial consumption is ≤0.55:1, which is used as the endpoint of the oxidation and impurity removal reaction to obtain a solution after impurity removal; wherein the pH value of the oxidation and impurity removal is 4.5-5; and the mass concentration of the impurity metal ions in the solution after impurity removal is <1 mg / L.

[0027] The application is judged by the consumption of neutralizer to remove the valence-varying impurity metal ion, i.e., the degree of progress of oxidation and impurity removal reaction, instructs the time of impurity removal, so that the utilization of neutralizer is more efficient, and then reduces the cost of oxidation and impurity removal process. Specifically, due to the significant weakening of its reaction degree in the oxidation and impurity removal reaction later stage, and acid generation reaction is dominant, causing the consumption of neutralizer to increase and waste, therefore, the application is by detecting the consumption of neutralizer in fixed time intervals, controlling the final consumption of neutralizer and the ratio of initial consumption in the above-mentioned range, it is possible to effectively reduce the additional consumption of neutralizer in the oxidation and impurity removal reaction later stage. The pH value of the preferred control oxidation and impurity removal is in the above-mentioned range, it is possible to ensure the effective precipitation of foreign metal ions, while reducing the loss of valuable metals, thereby improving its rate of recovery, simultaneously, it is also possible to further improve the use efficiency of neutralizer, prevent the acid generated due to oxidation reaction of oxidant from causing pH value too low, thereby ensuring the continuing of oxidation and impurity removal reaction, avoid the waste of overacidification and neutralizer. Furthermore, the determination method of the present application can not only ensure the effectiveness of oxidation removal, ensuring that the mass concentration of impurity metal ions in the solution after removal reaches the above range, but also effectively reduce process costs, thereby achieving good economic benefits. This method has good applicability to dynamically changing production processes.

[0028] In one embodiment of the present application, the oxidant is selected from any one or more of a mixed gas of SO2 gas and O2 gas, and flue gas.

[0029] The type of oxidant is preferably within the above range, which helps to reduce the introduction of impurity ions and thus improve the impurity removal effect of oxidation removal.

[0030] In one embodiment of the present application, the oxidant is a mixed gas of SO 2 gas and O 2 gas, and the volume ratio of SO 2 gas to O 2 gas is ≤0.5.

[0031] The preferred oxidant is a mixture of SO2 gas and O2 gas, and the volume ratio of SO2 gas to O2 gas is controlled within the above range, which helps to further promote the generation of HSO5 from SO2 and O2 at a pH of 4.5 to 5. - The generation of free radicals has a strong oxidizing ability for metal ions, which helps to further accelerate the oxidation and precipitation process of the impurity metals. When the mixed gas is passed into the solution to be removed containing impurity metal ions, a gas dispersion device (including but not limited to a microbubble generator, a gas injector or a vortex nozzle) can be used to increase the gas-liquid contact area, thereby improving the impurity removal effect of the oxidation removal.

[0032] When the volume of the solution to be removed is 1.5 L, the total flow rate of the mixed gas of SO 2 gas and O 2 gas is preferably 240 to 1160 mL / min.

[0033] In order to further improve the efficiency and effect of oxidation impurity removal, in one embodiment of the present application, the volume ratio of the oxidant to the solution to be removed is 0.2-1.16:1.5.

[0034] In one embodiment of the present application, the total initial mass concentration of the impurity metal ions in the solution to be removed is ≥5 g / L, and / or the impurity metal ions in the solution to be removed are selected from Mn 2+ ions, Fe 2+ ions, Fe 3+ ions and Cu 2+ Any one or more ions.

[0035] In addition, the solution to be removed may also include Al 3+ ions, Ni 2+ ions, Co 3+ ions, Mg 2+ ions and Cr 6+ Ions, etc., for the solution to be removed whose total initial mass concentration and types of impurity metal ions are within the above range, even if the types of ions in the solution to be removed are relatively complex, the method of the present application has good selectivity for the impurity metal ions, thereby achieving better precipitation and removal of the impurity metal ions.

[0036] In one embodiment of the present application, the oxidation and impurity removal is carried out under stirring conditions, and the stirring speed is 1000-1500 r / min; and / or the temperature of the oxidation and impurity removal is 20-25° C., and / or the time of the oxidation and impurity removal is 1.5-4 h.

[0037] The temperature and stirring speed of the oxidation removal process are preferably controlled within the above ranges to facilitate uniform distribution of the oxidant and impurity metal ions, thereby mitigating localized overly rapid or slow reactions and thereby improving the uniformity and effectiveness of the oxidation removal reaction. Stirring the oxidation removal process also helps reduce the accumulation of precipitates generated during the oxidation process at the bottom of the container, leading to localized low pH values, thereby improving the efficiency of the oxidation removal process.

[0038] In one embodiment of the present application, the fixed time interval is determined according to the total initial mass concentration of the impurity metal ions in the solution to be removed, and preferably the fixed time interval is 30 to 60 minutes.

[0039] The formula for calculating the fixed time interval is: Among them, T min Refers to the shortest time required for impurity removal, unit min, C Ini is the initial content of impurity ions, g / L, S Max is the maximum removal rate of impurity ions (g / L / min). 2+ In terms of test conditions, the measured S Maxis 0.04g / L / min, when C Ini At the 5g / L level, T min It is about 125min. But it is worth mentioning that it is difficult to continue to remove impurity ions after the concentration is removed to a certain extent, so the impurity removal time is generally longer than T min . Select a sampling interval of 0.25 to 0.5 times the T min That is, a fixed time interval of 30 to 60 minutes is more appropriate.

[0040] The preferred fixed time interval falls within the above range. This helps to simplify the operational process while ensuring the effectiveness of oxidation impurity removal, eliminating the need for frequent sampling and analysis, reducing the burden on operators. It also reduces the potential for errors introduced by frequent testing and improves the accuracy and repeatability of testing. Furthermore, a 30-60 minute interval is suitable for a variety of hydrometallurgical operations, whether continuous or intermittent production processes. Adjusting the testing frequency based on actual conditions helps ensure the stability of the impurity removal process.

[0041] In one embodiment of the present application, the neutralizing agent is selected from any one or more of 10-20 wt% MgO slurry, 10-20 wt% CaO slurry, NaOH and Ca(OH)2.

[0042] The type of neutralizing agent is preferably controlled within the above range to help regulate the pH of the reaction system. For example, when using SO2 and O2 as oxidants to remove metal impurities, additional sulfuric acid is produced. The use of a neutralizing agent helps neutralize this acid and maintain the pH of the oxidative impurity removal within an appropriate range, thereby helping to accelerate the oxidation rate of impurities and thereby improve the efficiency of the entire impurity removal process.

[0043] In one embodiment of the present application, the consumption of the neutralizer is the mass difference of the reaction system within each fixed time interval.

[0044] Since the oxidation of impurity ions is accompanied by the generation of acid, a neutralizer is required to maintain a stable pH in the system (to facilitate the continued removal of impurities). Therefore, there is a positive and stable correlation between the amount of neutralizer used and the oxidation of impurity metal ions. Therefore, the difference between the mass of the reaction system tested each time and the mass of the reaction system tested previously can be used to determine the amount of neutralizer consumed, helping to better reflect the degree of impurity removal achieved by oxidation-induced impurity removal.

[0045] In order to improve the utilization rate of the neutralizer and reduce the cost of the impurity removal process, in one embodiment of the present application, the ratio of the final consumption to the initial consumption is 0.4-0.55:1.

[0046] The beneficial effects of the present application will be further illustrated below with reference to embodiments.

[0047] Example 1

[0048] 40 mL / min SO2 gas and 200 mL / min O2 gas were introduced into 1.5 L of 5 g / L Mn 2+ The nickel, cobalt, copper and zinc hydrometallurgical extraction liquid is oxidized and impurities are removed, and 10wt% MgO slurry neutralizer is added to carry out neutralization reaction to obtain an initial reaction system.

[0049] The time is taken as the starting point of the timing when the oxidant is introduced into the solution, and the reaction system is weighed every 30 minutes. The consumption of the neutralizer is the mass difference of the reaction system within every 30 minutes. The result of the first test, that is, the difference between the mass of the first reaction system and the mass of the initial reaction system, is recorded as the initial consumption of the neutralizer. The ratio of the final consumption of the neutralizer to the initial consumption is 0.41:1 (the initial consumption is 79.04g and the final consumption is 32.19g). This is taken as the end point of the oxidation and impurity removal reaction to obtain the impurity-removed solution. The final oxidation and impurity removal time is 3h to terminate the reaction.

[0050] The neutralizing agent was continuously added during the whole process of the above oxidation and impurity removal by stirring, the pH value of the oxidation and impurity removal was 4.5, the temperature of the oxidation and impurity removal was 25° C., and the rotation speed of the oxidation and impurity removal was 1000 r / min.

[0051] Example 2

[0052] The difference from Example 1 is that the oxidant is 160 mL / min of SO2 gas and 1000 mL / min of O2 gas, and the ratio of final consumption to initial consumption is 0.49:1 (initial consumption is 272.3 g, and final consumption is 110.78 g). This is used as the end point of the oxidation and impurity removal reaction to obtain a de-impurity solution, and the final oxidation and impurity removal time is 1.5 h to terminate the reaction.

[0053] Example 3

[0054] The difference from Example 1 is that the pH value of the oxidation and impurity removal is 5, and the ratio of the final consumption to the initial consumption is 0.5:1 (the initial consumption is 72.01 g, and the final consumption is 36.67 g). This is used as the reaction end point of the oxidation and impurity removal to obtain the impurity-removed solution. The final oxidation and impurity removal time is 2.5 hours to terminate the reaction.

[0055] Example 4

[0056] The difference from Example 1 is that the Mn 2+The initial mass concentration of the ions was 5 g / L, the fixed time interval was 60 min, and the ratio of the final consumption to the initial consumption was 0.48:1 (the initial consumption was 145.27 g, and the final consumption was 69.88 g). This was used as the end point of the oxidation and impurity removal reaction to obtain the impurity-removed solution. The final oxidation and impurity removal time was 4 h to terminate the reaction.

[0057] Example 5

[0058] The difference from Example 1 is that the total flow rate of SO2 gas and O2 gas is 240 mL / min, the volume ratio of SO2 gas to O2 gas is 0.5:1, and the ratio of final consumption to initial consumption is 0.54:1 (initial consumption is 65.94 g, and final consumption is 35.83 g). This is used as the end point of the oxidation and impurity removal reaction to obtain a decontaminated solution, and the final oxidation and impurity removal time is 2.5 h to terminate the reaction.

[0059] Comparative Example 1

[0060] The difference from Example 1 is that the temperature of the oxidative decontamination is 40°C, the pH value of the oxidative decontamination is 4.5, the ratio of the consumption of the neutralizer to the initial consumption after oxidative decontamination for 4 hours is 0.71 (the initial consumption is 70g, and the consumption after oxidative decontamination for 4 hours is 50g), the reaction endpoint is not reached, and a decontaminated solution is obtained.

[0061] Comparative Example 2

[0062] The difference from Example 2 is that the pH value of the oxidative decontamination is 4.5, the ratio of the consumption of the neutralizer to the initial consumption after oxidative decontamination for 4 hours is 0.56 (the initial consumption is 90 g, and the consumption after oxidative decontamination for 4 hours is 50 g), the reaction endpoint is not reached, and a decontaminated solution is obtained.

[0063] Test method:

[0064] The mass concentration of impurity metal ions in the solution was determined using inductively coupled plasma mass spectrometry (ICP-MS) in accordance with HG781-2016.

[0065] Neutralizer consumption: measured by weighing method.

[0066] The impurity metal ions Mn in the solution after impurity removal in the above examples and comparative examples are 2+ The mass concentration of the test was tested, and the test results are shown in Table 1.

[0067] Table 1

[0068]

[0069] in, Figure 1 Mn in Example 1 2+The graph of the change of mass concentration of ions and consumption of neutralizer, from Figure 1 It can be seen that as the oxidation and impurity removal reaction proceeds, Mn 2+ The concentration of ions decreased significantly, and the consumption of neutralizer also showed a downward trend. The test was carried out every 30 minutes. When the final consumption of neutralizer was less than 1 / 2 of the initial consumption (dashed line position) after 3 hours of oxidation and impurity removal reaction, the Mn in the solution 2+ The ions are almost completely removed. According to the test results, the mass concentration is only about 0.67 mg / L. Therefore, controlling the ratio of the final consumption of the neutralizer to the initial consumption is ≤0.55 as the reaction end point, which can effectively ensure that Mn 2+ The removal depth of ions and the waste of neutralizer are avoided.

[0070] Figure 2 Mn in Example 2 2+ The graph of the change of mass concentration of ions and consumption of neutralizer, from Figure 2 It can be seen that when the final consumption of the neutralizer is less than 1 / 2 of the initial consumption (dashed line position) after 2.5h of oxidation and impurity removal reaction, the Mn in the solution 2+ The ions are almost completely removed, and according to the test results, their mass concentration is only about 0.10 mg / L.

[0071] Figure 3 Mn in Comparative Example 1 2+ The graph of the change of mass concentration of ions and consumption of neutralizer, from Figure 3 It can be seen that the final consumption of the neutralizer is still greater than 1 / 2 of the initial consumption (dashed line position) after 4 hours of oxidation and impurity removal reaction. According to the test results, the Mn 2+ The mass concentration of the ions was approximately 958.7 mg / L, and the end point of the impurity removal reaction was not reached, which proved the reliability of the method of the present application.

[0072] Figure 4 Mn in Comparative Example 2 2+ The graph of the change of mass concentration of ions and consumption of neutralizer, from Figure 4 It can be seen that the final consumption of the neutralizer is still greater than 1 / 2 of the initial consumption (dashed line position) after 4 hours of oxidation and impurity removal reaction. According to the test results, the Mn 2+ The mass concentration of the ions was approximately 912.7 mg / L, and the end point of the impurity removal reaction was not reached, which proved the reliability of the method of the present application.

[0073] It can be seen from the test results of Example 1 and Example 2 and Comparative Examples 1 and 2 that the determination method of the present application not only has a good oxidation and impurity removal effect on impurity metal ions, but also has good accuracy and repeatability in detecting the end point of the oxidation and impurity removal reaction.

[0074] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0075] The application is judged by the consumption of neutralizer to remove the valence-varying impurity metal ion, i.e., the degree of progress of oxidation and impurity removal reaction, instructs the time of impurity removal, so that the utilization of neutralizer is more efficient, and then reduces the cost of oxidation and impurity removal process. Specifically, due to the significant weakening of its reaction degree in the oxidation and impurity removal reaction later stage, and acid generation reaction is dominant, causing the consumption of neutralizer to increase and waste, therefore, the application is by detecting the consumption of neutralizer in fixed time intervals, controlling the final consumption of neutralizer and the ratio of initial consumption in the above-mentioned range, it is possible to effectively reduce the additional consumption of neutralizer in the oxidation and impurity removal reaction later stage. The pH value of the preferred control oxidation and impurity removal is in the above-mentioned range, it is possible to ensure the effective precipitation of foreign metal ions, while reducing the loss of valuable metals, thereby improving its rate of recovery, simultaneously, it is also possible to further improve the use efficiency of neutralizer, prevent the acid generated due to oxidation reaction of oxidant from causing pH value too low, thereby ensuring the continuing of oxidation and impurity removal reaction, avoid the waste of overacidification and neutralizer. Furthermore, the determination method of the present application can not only ensure the effectiveness of oxidation removal, ensuring that the mass concentration of impurity metal ions in the solution after removal reaches the above range, but also effectively reduce process costs, thereby achieving good economic benefits. This method has good applicability to dynamically changing production processes.

[0076] The above are merely embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for determining the end point of an oxidation and impurity removal reaction, characterized in that: The method comprises: Step S1, using an oxidant to oxidize and remove impurities from a solution containing impurity metal ions, and simultaneously adding a neutralizer to carry out a neutralization reaction to obtain a reaction system; and Step S2, starting from the time when the oxidant is first added to the solution to be decontaminated, detecting the consumption of the neutralizer within a fixed time interval, and recording the result of the first detection as the initial consumption of the neutralizer, until the ratio of the final consumption of the neutralizer to the initial consumption is ≤0.55:1, which is used as the reaction endpoint of the oxidation decontaminated reaction, to obtain a decontaminated solution; The pH value of the oxidation and impurity removal is 4.5 to 5; the mass concentration of impurity metal ions in the solution after impurity removal is less than 1 mg / L.

2. The method according to claim 1, characterized in that The oxidant is selected from any one or more of a mixed gas of SO2 gas and O2 gas, and flue gas.

3. The method according to claim 2, characterized in that The oxidant is a mixed gas of the SO2 gas and the O2 gas, and the volume ratio of the SO2 gas to the O2 gas is ≤0.

5.

4. The method according to any one of claims 1 to 3, characterized in that The volume ratio of the oxidant to the solution to be removed is 0.2-1.16:1.

5.

5. The method according to any one of claims 1 to 4, characterized in that The total initial mass concentration of the impurity metal ions in the solution to be removed is ≥5g / L, and / or the impurity metal ions in the solution to be removed are selected from Mn 2+ ions, Fe 2+ ions, Fe 3+ ions and Cu 2+ Any one or more ions.

6. The method according to any one of claims 1 to 5, characterized in that The oxidation and impurity removal is carried out under stirring conditions, the stirring speed is 1000-1500 r / min; and / or the temperature of the oxidation and impurity removal is 20-25° C., and / or the time of the oxidation and impurity removal is 1.5-4 hours.

7. The method according to claim 5, characterized in that The fixed time interval is determined according to the total initial mass concentration of the impurity metal ions in the solution to be removed, and preferably the fixed time interval is 30 to 60 minutes.

8. The method according to any one of claims 1 to 7, characterized in that The neutralizing agent is selected from any one or more of 10-20 wt% MgO slurry, 10-20 wt% CaO slurry, NaOH and Ca(OH)2.

9. The method according to any one of claims 1 to 8, characterized in that The consumption of the neutralizer is the mass difference of the reaction system within each fixed time interval.

10. The method according to any one of claims 4 to 9, characterized in that The ratio of the final consumption to the initial consumption is 0.4 to 0.55:1.

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