Method for deep removal of nickel and cobalt from wastewater solution

Abstract

The present invention relates to the technical field of wastewater treatment, and in particular to a method for deep removal of nickel and cobalt from wastewater solution. The method comprises sampling and monitoring to comprehensively recover cadmium-rich solution; zinc powder displacement to remove cadmium; cobalt removal agent to remove cobalt and nickel; and cobalt slag pickling. The present invention dissolves soluble metals (such as zinc, cadmium, etc.) in mixed slag into liquid through a leaching process, and removes cadmium by using zinc powder for displacement reaction in the obtained leaching solution. After removing cadmium, a cobalt removal agent is used to simultaneously remove cobalt and nickel in the solution. The cobalt removal agent is a selective chemical reagent that can effectively react with cobalt and nickel to form a precipitate, thereby removing them from the solution. The cobalt slag is pickled to recover metallic zinc, and the addition process of the cobalt removal agent is monitored in real time and the treatment effect is evaluated, thereby improving the automation and intelligence level of the operation, improving the removal efficiency, reducing the content of cobalt and nickel in the wastewater, and achieving a better wastewater treatment effect.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for deeply removing nickel and cobalt from a wastewater solution. Background Art

[0002] As the complexity of the raw material composition increases, the proportion of zinc oxide liquid in the middle and upper supernatant increases, resulting in the enrichment of impurities in the clean liquid workshop. This increases the unit consumption of zinc powder, and the new liquid cannot meet the requirements of deep purification. The cathode zinc precipitation in the electrolytic workshop is often poor, the electrical efficiency is low, and the unit consumption of DC power is high. In the hydrometallurgical zinc smelting, nickel is enriched in the system for a long time, resulting in an increase in the nickel content in the middle and upper supernatant, affecting the production of subsequent processes. The current main method of open-circuit nickel is to regularly send a batch of two-clean slag to the Austrian furnace for smelting and treatment to achieve the purpose of open-circuit nickel, but the current coal price is high, the processing cost is high, and the Austrian furnace needs to process other materials such as leached slag, and the processing of two-clean slag will occupy the Austrian furnace time. Therefore, it is considered to remove nickel while removing cobalt by using wet treatment methods in comprehensive recovery.

[0003] The existing zinc powder replacement cobalt removal has the following three disadvantages: (1) The reaction temperature is required to reach 85°C, which requires a large amount of steam, but the steam supply is unstable at this stage; (2) Although the test results of various conventional element indicators of the new liquid are often within the normal range, the zinc precipitation at the electrolytic cathode is not good, indicating that the comprehensive impurity removal ability is poor; (3) The first and second clean slags contain incompletely reacted zinc powder. In order to recover this part of the metal, some impurities will be leached into the liquid during the subsequent acid leaching process, resulting in the enrichment of impurities.

[0004] The patent document of Chinese patent application publication number CN117003441A discloses a process for recovering cobalt and nickel from cobalt-containing wastewater, which comprises the following steps: 1) removing the organic phase from the cobalt-containing wastewater to obtain wastewater A; 2) adding a carbon source to the waste material for grinding, heating and heat preservation, cooling to room temperature, adding dilute nitric acid, adjusting the pH value for reaction, filtering, and obtaining wastewater B; 3) mixing wastewater A and wastewater B, adjusting the pH value, adding sodium sulfide aqueous solution, heating for reaction, filtering, and obtaining filtrate A; 4) adding the filtrate to the filtrate. A) adds an oxidant, adjusts the pH value, and filters to obtain a filtrate B; wherein the oxidant is hypochlorite or chlorate; 5) grinds the carbonate and adds deionized water thereto, adjusts the pH value and concentration to obtain a slurry, sprays the slurry into the filtrate B, controls the temperature for reaction, and filters to obtain a filtrate C; 6) adds a sulfide salt to the filtrate C, heats the reaction, and filters to obtain a filter residue D; Therefore, in the existing wet zinc smelting process, there is a lack of stirring treatment steps for accurately monitoring impurity elements, controlling cadmium content, and ensuring that indium extraction is not affected, resulting in poor impurity removal ability. Summary of the invention

[0005] To this end, the present invention provides a method for deep removal of nickel and cobalt from a wastewater solution, so as to overcome the problem in the prior art of lack of precise monitoring and adjustment of the nickel stirring process for cobalt removal, resulting in poor nickel and cobalt removal effect.

[0006] To achieve the above object, the present invention provides a method for deep removal of nickel and cobalt from wastewater, comprising:

[0007] Step S1, collecting the comprehensive recovery cadmium-rich liquid at the water outlet of the comprehensive recovery workshop, sampling and monitoring the comprehensive recovery cadmium-rich liquid to obtain an initial zinc content, an initial cobalt content, an initial nickel content, an initial iron content and an initial cadmium content;

[0008] Step S2, calculating the total amount of zinc powder added according to the initial cadmium content, adding zinc powder to the comprehensive recovery cadmium-rich solution with the total amount of zinc powder added, stirring and reacting for 30 minutes under the first water bath temperature condition, filtering the liquid with suction, the filtrate is a cadmium-poor liquid, and the filter residue is a sponge cadmium, determining the first actual content of zinc, cadmium, cobalt, nickel, and iron in the filtrate, and calculating the total amount of cobalt removal agent added according to the first actual content;

[0009] Step S3, taking the cadmium-depleted solution, adding an activator under the second water bath temperature condition, stirring the reaction for 10 minutes, and then slurrying a corresponding mass of a cobalt removal agent at a preset addition rate to form a mixed solution, and monitoring the process of adding the cobalt removal agent to the mixed solution in real time until it is determined that the cobalt-nickel removal process is completed, obtaining a purified liquid and filtering it, obtaining a filtrate as a cobalt-removed liquid, and a filter residue as a cobalt removal agent residue;

[0010] The uniformity of the mixed solution is analyzed according to the detection data of each arranged sampling point, and when the mixed solution is determined to be non-uniform, the real-time rotation speed variation is determined to control the stirring paddle to extend at a standard displacement distance, or to analyze whether the stirring state is abnormal;

[0011] Step S4, performing pickling treatment on the cobalt slag to obtain pickling solution and cobalt slag.

[0012] Further, real-time monitoring of the process of adding the cobalt removal agent to the mixed solution includes:

[0013] The real-time content difference corresponding to each sampling point is sequentially obtained in a preset monitoring period, the maximum content difference is calculated according to the real-time content difference, the standard content difference is compared with the maximum content difference, and whether the mixed solution is uniform is analyzed according to the comparison result;

[0014] When it is determined that the mixed solution is not uniform, the real-time speed variation is obtained, and the real-time speed variation is determined according to the standard speed variation to control the extension of the stirring paddle or obtain the analysis point;

[0015] Analyze the position of the analysis point, and determine whether the stirring is abnormal according to the analysis result;

[0016] When there is no abnormality in stirring, adjust the preset addition speed;

[0017] The cobalt content of the mixed solution at any sampling point is obtained at a preset sampling interval, a curve of the cobalt content of the mixed solution changing over time is drawn, the change curve is analyzed, and whether the cobalt-nickel removal process is completed is determined based on the analysis result.

[0018] Further, analyzing whether the mixed solution is uniform according to the comparison result includes:

[0019] When the maximum content difference is less than or equal to the standard content difference, the mixed solution is determined to be uniform;

[0020] When the maximum content difference is greater than the standard content difference, the mixed solution is determined to be uneven, the real-time stirring speed and the preset stirring speed are obtained, the absolute value of the difference between the real-time stirring speed and the preset stirring speed is calculated, and the real-time rotation speed variation is obtained.

[0021] Further, when determining that the mixed solution is not uniform, determining the real-time speed variation according to the standard speed variation includes:

[0022] When the real-time speed variation is less than or equal to the standard speed variation, the stirring paddle is controlled to extend at the standard displacement distance;

[0023] When the real-time speed variation is greater than the standard speed variation, the collection point corresponding to the maximum content difference is obtained to obtain the analysis point, the position of the analysis point is analyzed, and whether the stirring is abnormal is determined according to the analysis result;

[0024] Among them, the standard displacement distance is 1 / 5 of the distance between the stirring paddle and the bottom of the tank;

[0025] Further, when the real-time speed variation is greater than the standard speed variation, analyzing the position of the analysis point includes:

[0026] If the analysis point is in the bottom area, it is determined that the stirring is normal, the preset addition speed is adjusted to a corrected addition speed, and the cobalt removal agent is added to the solution at the preset addition speed;

[0027] If the analysis point is located in a non-bottom area, it is determined that the stirring is abnormal, and the preset stirring speed is adjusted to a corrected stirring speed;

[0028] Among them, Uc'=Uc×[1+(ΔQs-ΔQb) / ΔQs], Vc'=Vc×[1+(ΔQs-ΔQb) / ΔQs], Uc' is the corrected addition speed, Uc is the preset addition speed, Vc' is the corrected stirring speed, Vc is the preset stirring speed, ΔQs is the real-time speed deviation, and ΔQb is the standard speed deviation.

[0029] Further, analyzing the change curve includes:

[0030] Obtain the slope of the line segment between any adjacent sampling points for determination. When the slope is less than or equal to zero, continue to obtain the real-time content difference corresponding to each sampling point in the next preset monitoring period for analysis and determination;

[0031] When the slope is greater than zero, the standard reaction time is obtained, and it is determined that the cobalt-nickel removal process is completed.

[0032] Further, calculating the maximum content difference according to the real-time content difference includes,

[0033] The reaction tank is divided into a number of equally spaced areas using a straight line parallel to the tank bottom to obtain corresponding monitoring area units;

[0034] For any of the monitoring area units, respectively obtain the real-time cobalt content collected at each sampling point, and calculate the average cobalt content of the monitoring area unit as the unit cobalt content;

[0035] Add the cobalt content of each unit and divide it by the number of units in the monitoring area to obtain the real-time cobalt content of the reaction tank;

[0036] Subtract the cobalt content of each unit from the real-time cobalt content to obtain the difference of cobalt content of several units;

[0037] The absolute value of the cobalt content difference of each unit is taken, and the maximum value among the absolute values ​​is obtained as the maximum content difference of the reaction tank.

[0038] Furthermore, the total amount of zinc powder added is 0.9 times the initial cadmium content, and the temperature condition of the first water bath is a constant temperature of 45-50°C.

[0039] Furthermore, the total amount of the cobalt removal agent added is 5-10 times the sum of the mass of cobalt and nickel, or 4-8 times the sum of the mass of cadmium and iron; the amount of the activator added is one tenth of the amount of the cobalt removal agent added;

[0040] The cobalt removal agent is sodium dimethyldithiocarbamate.

[0041] Furthermore, the pickling process is as follows:

[0042] Add sulfuric acid solution to the cobalt removal agent slag under preset pickling conditions for pickling, keep the water bath at a constant temperature of 75-80° C., stir and react for 60 minutes, and then filter the liquid to obtain a pickling solution and cobalt slag;

[0043] Among them, the preset pickling conditions are the initial acid sulfuric acid concentration and the liquid-solid ratio. The initial acid sulfuric acid concentration is between 100g / L-200g / L, and the liquid-solid ratio is 5:1.

[0044] Compared with the prior art, the beneficial effect of the present invention lies in that the soluble metals (such as zinc, cadmium, etc.) in the mixed slag are dissolved into the liquid through the leaching process, and the cadmium is removed by using zinc powder to carry out a replacement reaction in the obtained leaching solution. After the cadmium is removed, a cobalt removal agent is used to simultaneously remove the cobalt and nickel in the solution. The cobalt removal agent is a selective chemical reagent that can effectively react with cobalt and nickel to form a precipitate, thereby removing them from the solution, and the cobalt slag is pickled to recover the metallic zinc.

[0045] Furthermore, an intelligent monitoring method is used to realize automatic control of the removal of cobalt and nickel from the cadmium-depleted solution, thereby improving production efficiency, reducing manual intervention, and improving product quality.

[0046] Furthermore, by sampling and testing the cobalt content at different positions and depths in the reaction tank, the specific area and degree of unevenness can be determined so that more targeted adjustments and optimizations can be made. By testing the cobalt content in the solution and analyzing its distribution uniformity, the addition process of the cobalt removal agent can be monitored in real time and the treatment effect can be evaluated, thereby improving the level of automation and intelligence of operations, reducing manual intervention, and improving production efficiency.

[0047] Furthermore, the real-time speed variation is judged according to the standard speed variation to analyze the cause of the uneven solution. When the real-time speed variation is judged to be less than or equal to the standard speed variation, it means that the speed resistance is small and the stirring operation is normal. At this time, due to the accumulation of materials in the bottom area of ​​the reaction tank body, in order to ensure that the materials at the bottom of the tank can also be fully stirred, the stirring paddle is moved down to ensure that the cobalt in the solution is evenly distributed, so that the cobalt removal agent can react more fully with the cobalt and nickel impurities, improve the removal efficiency, reduce the cobalt and nickel content in the wastewater, and achieve better wastewater treatment effects.

[0048] Furthermore, by obtaining the specific location of the uneven distribution of cobalt when the speed variation is large, the actual speed is slowed down due to the formation of precipitation in the bottom area of ​​the reaction tank. In this case, the reaction liquid has poor local flow, resulting in high concentration in the local area. The addition rate of the cobalt removal agent is slowed down to avoid the precipitation from gathering in a certain area at the bottom, causing the cobalt to be unevenly distributed in the solution. The large speed variation may be caused by precipitation formation or excessive resistance, which causes the actual speed to slow down. At this time, the speed is increased to overcome the resistance and ensure the stirring effect.

[0049] Furthermore, as the reaction time increases, the re-dissolution of cobalt will increase. Therefore, as the reaction time increases, the cobalt content of the solution is monitored in real time. By setting a preset collection interval, the cobalt content of the solution is monitored in real time to accurately determine whether the cobalt and nickel removal process is completed, thereby achieving automatic control of the removal of cobalt and nickel in the cadmium-depleted solution and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic flow chart of a method for deep removal of nickel and cobalt from a wastewater solution according to an embodiment of the present invention;

[0051] Figure 2 A logic decision diagram for analyzing whether a mixed solution is uniform according to an embodiment of the present invention;

[0052] Figure 3 A logic decision diagram for controlling the extension of a stirring paddle according to an embodiment of the present invention;

[0053] Figure 4 This is a logic decision diagram for determining whether stirring is abnormal in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0056] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0057] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] See also Figure 1As shown, it is a schematic flow diagram of a method for deep removal of nickel and cobalt from a wastewater solution according to an embodiment of the present invention. The present invention provides a method for deep removal of nickel and cobalt from a wastewater solution, comprising:

[0059] Step S1, collecting the comprehensive recovery cadmium-rich liquid at the water outlet of the comprehensive recovery workshop, sampling and monitoring the comprehensive recovery cadmium-rich liquid to obtain an initial zinc content, an initial cobalt content, an initial nickel content, an initial iron content and an initial cadmium content;

[0060] Step S2, calculating the total amount of zinc powder added according to the initial cadmium content, adding zinc powder to the comprehensive recovery cadmium-rich solution with the total amount of zinc powder added, stirring and reacting for 30 minutes under the first water bath temperature condition, filtering the liquid with suction, the filtrate is a cadmium-poor liquid, and the filter residue is a sponge cadmium, determining the first actual content of zinc, cadmium, cobalt, nickel, and iron in the filtrate, and calculating the total amount of cobalt removal agent added according to the first actual content;

[0061] The total amount of zinc powder added is 0.9 times the real-time cadmium content, and the first water bath temperature condition is a constant water bath temperature of 45-50°C;

[0062] Step S3, taking the cadmium-depleted solution, adding an activator under the second water bath temperature condition, stirring the reaction for 10 minutes, and then slurrying a corresponding mass of a cobalt removal agent at a preset addition rate to form a mixed solution, and monitoring the process of adding the cobalt removal agent to the mixed solution in real time until it is determined that the cobalt-nickel removal process is completed, obtaining a purified liquid and filtering it, obtaining a filtrate as a cobalt-removed liquid, and a filter residue as a cobalt removal agent residue;

[0063] The total amount of the cobalt removal agent added is calculated according to the first actual content, the amount of the cobalt removal agent added is 5-10 times the sum of the mass of cobalt and nickel, or 4-8 times the sum of the mass of cadmium and iron, the amount of the activator added is one tenth of the amount of the cobalt removal agent added, the cobalt removal agent is sodium dimethyldithiocarbamate, and the temperature condition of the second water bath is a constant temperature of 85°C;

[0064] Step S4, performing pickling treatment on the cobalt slag to obtain pickling solution and cobalt slag.

[0065] Wherein, the process of pickling treatment is:

[0066] Add sulfuric acid solution to the cobalt removal agent slag under preset pickling conditions for pickling, keep the water bath at a constant temperature of 75-80° C., stir and react for 60 minutes, and then filter the liquid to obtain a pickling solution and cobalt slag;

[0067] Among them, the preset pickling conditions are the initial acid sulfuric acid concentration and liquid-to-solid ratio, the initial acid sulfuric acid concentration is between 100g / L-200g / L, and the liquid-to-solid ratio is 5:1;

[0068] In hydrometallurgical zinc smelting, nickel is enriched in the system for a long time, resulting in an increase in the nickel content in the supernatant, which affects the production of the subsequent processes. The current main method of open-circuit nickel is to regularly send a batch of two-clean slag to the Austrian furnace for smelting and treatment to achieve the purpose of open-circuit nickel, but the current coal price is high, the processing cost is high, and the Austrian furnace needs to process other materials such as leached slag, and the processing of two-clean slag will occupy the Austrian furnace time. Therefore, the comprehensive recovery method of wet treatment is used to remove nickel while removing cobalt. Under the conditions of stable nickel content in zinc concentrate and stable leaching rate, the nickel content in the supernatant is reduced to below 20 mg / L.

[0069] The soluble metals (such as zinc, cadmium, etc.) in the mixed slag are dissolved into the liquid through the leaching process. The cadmium is removed by using zinc powder to carry out a replacement reaction in the obtained leaching solution. After the cadmium is removed, the cobalt and nickel in the solution are removed simultaneously by using a cobalt removal agent. The cobalt removal agent is a selective chemical reagent that can effectively react with cobalt and nickel to form a precipitate, thereby removing them from the solution. The stirring process of the mixed solution is monitored in real time, and the uniformity of the mixed solution is analyzed according to the detection data of each sampling point. When the mixed solution is determined to be uneven, the real-time speed variation is determined to control the stirring paddle to extend at a standard displacement distance, or to analyze whether the stirring state is abnormal, so as to timely adjust the stirring speed or the addition speed of the cobalt removal agent to ensure the uniformity of the mixed solution and improve the intelligence of the stirring process. The cobalt slag is pickled to recover metallic zinc.

[0070] Specifically, real-time monitoring of the process of adding the cobalt removal agent to the mixed solution includes:

[0071] The real-time content difference corresponding to each sampling point is obtained in sequence according to the preset monitoring period, the maximum content difference is calculated according to the real-time content difference, the standard content difference is compared with the maximum content difference, and whether the mixed solution is uniform is analyzed according to the comparison result;

[0072] When it is determined that the mixed solution is not uniform, the real-time speed variation is obtained, and the real-time speed variation is determined according to the standard speed variation to control the extension of the stirring paddle or obtain the analysis point;

[0073] Analyze the position of the analysis point, and determine whether the stirring is abnormal according to the analysis result;

[0074] When there is no abnormality in stirring, adjust the preset addition speed;

[0075] The cobalt content of the mixed solution at any sampling point is obtained at a preset sampling interval, a curve of the cobalt content of the mixed solution changing over time is drawn, the change curve is analyzed, and whether the cobalt-nickel removal process is completed is determined based on the analysis result.

[0076] Through intelligent monitoring methods, automatic control of the removal of cobalt and nickel from cadmium-depleted liquid can be achieved, thereby improving production efficiency, reducing manual intervention and improving product quality.

[0077] See also Figure 2 As shown, it is a logic determination diagram for analyzing whether a mixed solution is uniform according to an embodiment of the present invention;

[0078] Specifically, analyzing whether the mixed solution is uniform according to the comparison results includes,

[0079] When the maximum content difference is less than or equal to the standard content difference, the mixed solution is judged to be uniform;

[0080] When the maximum content difference is greater than the standard content difference, the mixed solution is determined to be uneven, the real-time stirring speed and the preset stirring speed are obtained, and the absolute value of the difference between the real-time stirring speed and the preset stirring speed is calculated to obtain the real-time rotation speed variation.

[0081] The standard content difference in this embodiment represents the allowable cobalt content difference, that is, it measures whether the cobalt distribution in the reaction solution is uniform. The set value of the standard content difference is related to the initial cobalt content and the reaction time. Generally, it is set between 3% and 5% of the cobalt content measured at the initial moment of the current monitoring cycle, and is selected and adjusted according to the performance and specifications of the reaction tank equipment. The preset sampling interval is set between 30 minutes and 40 minutes, and the preset monitoring period is between 10 minutes and 15 minutes, and is selected according to the actual reaction requirements.

[0082] The standard content difference in this embodiment is measured in advance by experiment. The same batch of cobalt removal agent and cadmium-depleted solution as in this embodiment is prepared. An activator is added to the cadmium-depleted solution. After stirring for 10 minutes, a corresponding mass of cobalt removal agent is slurried and added at a preset addition speed to simulate the actual situation during the cobalt removal operation. The real-time cobalt content difference of each sampling point is calculated in each monitoring period. The effect of identifying the uneven distribution of cobalt content under different standard cobalt content differences is analyzed. The changes in the false alarm rate and the missed alarm rate under different standard cobalt content differences are analyzed, as shown in Table 1.

[0083] Table 1

[0084] Monitoring cycle Standard cobalt content difference (ppm) False Positive Rate False negative rate 1 200×3%=6 10% 5% 1 200×4%=8 5% 10% 1 200×5%=10 2% 15% 2 100×3%=3 8% 3% 2 100×4%=4 4% 7% 2 100×5%=5 1% 12% 3 66×3%=1.98 6% 2% 3 66×4%=2.64 3% 5% 3 66×5%=3.3 0% 10%

[0085] As shown in Table 1, by monitoring the removal efficiency of cobalt as the monitoring cycle progresses, the results show that the optimal standard cobalt content difference of the cobalt removal agent is 5% of the cobalt content measured at the initial moment of the current monitoring cycle.

[0086] By sampling and testing the cobalt content at different positions and depths in the reaction tank, the specific area and degree of unevenness can be determined so that more targeted adjustments and optimizations can be made. By testing the cobalt content in the solution and analyzing its distribution uniformity, the addition process of the cobalt removal agent can be monitored in real time and the treatment effect can be evaluated, thereby improving the level of automation and intelligence of operations, reducing manual intervention, and improving production efficiency.

[0087] See also Figure 3 As shown, it is a logic determination diagram for controlling the extension of the stirring paddle according to an embodiment of the present invention;

[0088] Specifically, when determining that the mixed solution is not uniform, determining the real-time speed variation according to the standard speed variation includes:

[0089] When the real-time speed variation is less than or equal to the standard speed variation, the stirring paddle is controlled to extend at the standard displacement distance;

[0090] When the real-time speed variation is greater than the standard speed variation, the collection point corresponding to the maximum content difference is obtained to obtain the analysis point, the position of the analysis point is analyzed, and whether the stirring is abnormal is determined according to the analysis result;

[0091] Among them, the standard displacement distance is 1 / 5 of the distance between the stirring paddle and the bottom of the tank;

[0092] The standard speed variation in this embodiment indicates the permissible stirring speed error. Within this error, the stirring state is good. Generally, it is set at 300 revolutions per minute and adjusted according to the actual stirring blade type and process requirements.

[0093] The preset stirring speed is 500rpm, and the selection and adjustment are adapted according to the characteristics of the stirring paddle, the actual processing requirements, and the equipment specifications. It is only necessary to ensure that the best mixing effect is achieved. In order to stabilize the stirring during the mixing process, avoid too fast stirring speed, and increase the risk of uncontrolled reaction, the preset addition speed is a smaller value set, and the preset stirring speed is adaptively increased according to the control method in the present embodiment to ensure the stability and quality of the mixing process. The real-time speed variation is judged according to the standard speed variation to analyze the cause of the uneven solution. When it is judged that the real-time speed variation is less than or equal to the standard speed variation, it means that the speed resistance is small and the stirring operation is normal. At this time, due to the accumulation of materials in the bottom area of ​​the reactor tank body, in order to ensure that the tank bottom material can also be fully stirred, the stirring paddle is moved down to ensure that the distribution of cobalt in the solution is uniform, so that the cobalt removal agent can react more fully with the cobalt-nickel impurities, improve the removal efficiency, reduce the content of cobalt-nickel in the wastewater, and achieve better wastewater treatment effect.

[0094] See also Figure 4 As shown, it is a logic determination diagram for determining whether stirring is abnormal according to an embodiment of the present invention;

[0095] Specifically, when the real-time speed variation is greater than the standard speed variation, analyzing the position of the analysis point includes:

[0096] If the analysis point is in the bottom area, it is determined that the stirring is normal, the preset addition speed is adjusted to a corrected addition speed, and the cobalt removal agent is added to the solution at the preset addition speed;

[0097] If the analysis point is located in a non-bottom area, it is determined that the stirring is abnormal, and the preset stirring speed is adjusted to a corrected stirring speed;

[0098] Among them, Uc'=Uc×[1-(ΔQs-ΔQb) / ΔQs], Vc'=Vc×[1+(ΔQs-ΔQb) / ΔQs], Uc' is the corrected addition speed, Uc is the preset addition speed, Vc' is the corrected stirring speed, Vc is the preset stirring speed, ΔQs is the real-time speed variation, and ΔQb is the standard speed variation.

[0099] The preset addition speed in this embodiment is 180ml / min, which is selected and adjusted according to the type, capacity and characteristics of the stirring equipment. In order to avoid the addition speed being too small, which will lead to insufficient mixing time of the cobalt removal agent and other substances, and the contact between the cobalt removal agent and other substances and limit the reaction rate, the preset addition speed is set to a larger value. According to the control method in this embodiment, the preset addition speed is adaptively reduced to improve production efficiency while ensuring the uniformity and stability of mixing. By obtaining the specific location of uneven cobalt distribution when the speed variation is large, the actual speed is slowed down due to the formation of precipitation in the bottom area of ​​the reactor body. In this case, the reaction liquid has poor local flow, resulting in high concentration in the local area. The addition speed of the cobalt removal agent is slowed down to avoid the precipitation from gathering in a certain area at the bottom, so that the cobalt is unevenly distributed in the solution; the speed variation is large, which may be caused by precipitation formation or excessive resistance, resulting in a slowdown in the actual speed. At this time, the speed is increased to overcome the resistance and ensure the stirring effect.

[0100] The stirring speed is adjusted according to the cobalt distribution and the speed variation to make the stirring more reasonable and effective, reduce energy waste and improve the operating efficiency of the equipment.

[0101] Specifically, analyzing the change curve includes:

[0102] Obtain the slope of the line segment between any adjacent sampling points for determination. When the slope is less than or equal to zero, continue to obtain the real-time content difference corresponding to each sampling point in the next preset monitoring period for analysis and determination;

[0103] When the slope is greater than zero, the standard reaction time is obtained, and it is determined that the cobalt-nickel removal process is completed.

[0104] The standard reaction time in this embodiment is the inflection point where the cobalt content begins to decrease and then gradually increases. Generally, the standard reaction time is about 90 minutes. As the reaction time is prolonged, the re-dissolution of cobalt will increase. Therefore, as the reaction time is prolonged, the cobalt content of the solution is monitored in real time. By setting a preset collection interval, the cobalt content of the solution is monitored in real time to accurately determine whether the cobalt and nickel removal process is completed, thereby achieving automatic control of the removal of cobalt and nickel in the cadmium-depleted solution and improving production efficiency.

[0105] Specifically, calculating the maximum content difference value based on the real-time content difference value includes:

[0106] The reaction tank is divided into a number of equally spaced areas using a straight line parallel to the tank bottom to obtain corresponding monitoring area units;

[0107] For any of the monitoring area units, respectively obtain the real-time cobalt content collected at each sampling point, and calculate the average cobalt content of the monitoring area unit as the unit cobalt content;

[0108] Add the cobalt content of each unit and divide it by the number of units in the monitoring area to obtain the real-time cobalt content of the reaction tank;

[0109] Subtract the cobalt content of each unit from the real-time cobalt content to obtain the difference of cobalt content of several units;

[0110] The absolute value of the cobalt content difference of each unit is taken, and the maximum value among the absolute values ​​is obtained as the maximum content difference of the reaction tank.

[0111] The content difference is the change in cobalt content at different sampling points. A larger content difference indicates a higher cobalt content, that is, the cobalt content at the corresponding sampling point is significantly different from that in other areas, making the reaction liquid uneven. Therefore, the content difference is monitored in real time to ensure the uniformity of cobalt distribution, ensure the stability and reliability of the cobalt-nickel removal process, and ensure the smooth progress of the wastewater treatment process.

[0112] Specifically, the experimental process to explore the effect of cobalt removal agent on indium extraction is as follows:

[0113] Experiment 1: Take 200 mL of the primary filtrate (cadmium-poor solution), keep the water bath at a constant temperature of 30°C, add it to the separatory funnel, then add 100 mL of the extractant, and oscillate and extract for 2 minutes. After the organic phase and the aqueous solution are separated, the two phases are separated, and the In content of the pre-extraction liquid and the post-extraction liquid is determined respectively, and the extraction rate is calculated.

[0114] Experiment 2: Take 1000mL of the primary filtrate (cadmium-depleted liquid), add 5g of cobalt removal agent and 0.5g of activator, keep the temperature in a water bath at 85℃, stir and react for 2 hours, filter the liquid, cool the filtrate and keep the temperature in a water bath at 30℃, take 200mL of the filtrate and add it to a separatory funnel, then add 100mL of the extractant, oscillate and extract for 2 minutes, separate the organic phase and the aqueous solution after they are separated, determine the In content of the liquid before and after the extraction, and calculate the extraction rate.

[0115] Experiment 3: Take 1000mL of the primary filtrate (cadmium-depleted liquid), add 15g of cobalt removal agent and 1.5g of activator, keep the temperature in a water bath at 85℃, stir and react for 2 hours, filter the liquid, cool the filtrate and keep the temperature in a water bath at 30℃, take 200mL of the filtrate and add it to the separatory funnel, then add 100mL of the extractant, oscillate and extract for 2 minutes, separate the organic phase and the aqueous solution after they are separated, determine the In content of the liquid before and after the extraction, and calculate the extraction rate.

[0116] Experiment 4: Take 1000mL of the primary filtrate (cadmium-depleted liquid), add 5g of cobalt removal agent and 0.5g of activator, keep the temperature in a water bath at 85℃, stir and react for 2 hours, filter the liquid, add 5g of activated carbon to the filtrate and stir and react for 20 minutes, filter the liquid, cool the filtrate and keep the temperature in a water bath at 30℃, take 200mL of the filtrate and add it to a separatory funnel, add 100mL of the extractant, oscillate and extract for 2 minutes, separate the organic phase and the aqueous solution after they are separated, determine the In content of the liquid before and after the extraction, and calculate the extraction rate.

[0117] Experiment 5: Take 1000mL of the primary filtrate (cadmium-depleted liquid), add 15g of cobalt removal agent and 1.5g of activator, keep the temperature in a water bath at 85℃, stir and react for 2 hours, filter the liquid, add 5g of activated carbon to the filtrate and stir and react for 20 minutes, filter the liquid, cool the filtrate and keep the temperature in a water bath at 30℃, take 200mL of the filtrate and add it to a separatory funnel, add 100mL of the extractant, oscillate and extract for 2 minutes, separate the organic phase and the aqueous solution after they are separated, determine the In content of the liquid before and after extraction, and calculate the extraction rate.

[0118] The experimental results are shown in Table 2.

[0119] Table 2

[0120] Group Experiment 1 Experiment 2 Experiment 3 Experiment 4 Experiment 5 Extraction rate 92.9% 92.8% 91.1% 91.5% 91.3%

[0121] According to Table 2, the cobalt removal agent has no effect on indium extraction.

[0122] Specifically, the effect of cobalt removal agent slag pickling solution on indium extraction was investigated and verified by the following experiments:

[0123] Experiment 1: Pre-extraction solution: Take 1000mL of the primary filtrate (cadmium-poor solution), add distilled water and concentrated sulfuric acid (98%), make the volume up to 2000mL, make the liquid contain 170g / L H2SO4, take a sample and test the indium content of the pre-extraction solution.

[0124] Experiment 2: Pre-extraction liquid: Take 1000mL of cobalt slag pickling liquid, add clean filtrate and concentrated sulfuric acid (98%), make the volume to 2000mL, make the liquid contain H2SO4 to reach 170g / L, take a sample and test the indium content of the pre-extraction liquid.

[0125] Preparation of cobalt slag pickling solution in Experiment 2: Take 4000mL of cadmium-rich solution (i.e., mixed slag leaching solution) from the comprehensive recovery workshop, add 50g of zinc powder, keep the water bath at a constant temperature of 65-70℃, stir and react for 40 minutes, filter, and test the filtrate for cadmium and cobalt. Add 50g of zinc powder again, keep the water bath at a constant temperature of 65-70℃, stir and react for 30 minutes, filter, and test the filtrate to find out if the cadmium content is less than 50mg. Add a cobalt removal agent at 20 times the cobalt content in the filtrate, keep the water bath at a constant temperature of 80℃, stir and react for 2 hours, filter, and obtain the cobalt removal agent slag. Mix the obtained slag with 1000mL of electrolytic waste liquid, add an appropriate amount of sulfuric acid (1:1) to make the liquid contain 180g / L of H2SO4, bath at 80℃, stir and react for 2 hours, filter to obtain the cobalt slag pickling solution, and test the H2SO4 content in the cobalt slag pickling solution.

[0126] The experiment recycled the organic phase according to the process of extraction - sulfuric acid washing - hydrochloric acid stripping - oxalic acid washing. The specific operations of each process are as follows:

[0127] (1) Extraction: Take 100 mL of lean organic phase and 200 mL of pre-extraction solution and add them into a 1000 mL separatory funnel. Oscillate and extract for 2 minutes. Let the layers stand and release the aqueous phase, which is the raffinate. The raffinate is tested for indium content.

[0128] (2) Sulfuric acid washing: Take 100 mL of 100 g / L sulfuric acid solution and add it to the separatory funnel in (1), mix it with the loaded organic phase, extract it by oscillation for 2 minutes, let it stand to separate the layers, and discard the aqueous phase.

[0129] (3) Hydrochloric acid stripping: Take 100 mL of 6 mol / L hydrochloric acid solution and add it to the separatory funnel in (2), mix it with the loaded organic phase, extract it by oscillation for 2 minutes, let it stand and separate the layers, and release the aqueous solution phase, which is the stripping solution. The stripping solution is tested for indium content.

[0130] (4) Oxalic acid washing: Take 100 mL of 7% oxalic acid solution and add it to the separatory funnel in (3), mix it with the lean organic phase, extract it by oscillation for 2 minutes, let it stand to separate the layers, discard the aqueous phase, and return the organic phase to (1) for recycling.

[0131] Specifically, the following experiments were conducted to investigate whether the cobalt removal agent would be enriched in the organic phase during use, resulting in a significant decrease in the extraction rate:

[0132] Experiment 3: Pre-extraction solution: Take 2000 mL of the clean filtrate as the pre-extraction solution and test the indium content.

[0133] Experiment 4: Pre-extraction liquid: Take 2000mL of clean filtrate, add 10g of cobalt removal agent and 1g of activator, keep the water bath at a constant temperature of 80℃, stir and react for 2 hours, filter the liquid, and the filtrate is the pre-extraction liquid, and test the indium content.

[0134] Experiment 5: Pre-extraction liquid: Take 2000mL of clean filtrate, add 10g of cobalt removal agent, 1g of activator, keep the water bath temperature at 80℃, stir and react for 2 hours, filter the liquid, add 10g of activated carbon to the filtrate, stir and adsorb for 30 minutes, filter, and the filtrate is the pre-extraction liquid, test the indium content.

[0135] The experiment recycled the organic phase according to the process of extraction-sulfuric acid washing-hydrochloric acid stripping-oxalic acid washing, and carried out 6 cycle experiments. The specific operation methods of each process were the same as those in the experiment to explore the effect of cobalt removal agent slag pickling solution on indium extraction.

[0136] The experimental results are shown in Table 3.

[0137] Table 3

[0138] Pre-extraction liquid group Experiment 1 Experiment 2 Experiment 3 Experiment 4 Experiment 5 Extraction rate 99.9% 99.8% 98.1% 98.5% 98.3%

[0139] According to Table 3, the cobalt slag pickling solution has no effect on indium extraction.

[0140] Specifically, the nickel content and cobalt recovery rate of the supernatant measured at different times by the method of the embodiment of the present invention were compared with the nickel content and cobalt recovery rate of the supernatant measured by the conventional nickel removal method. The comparison results are shown in Table 3;

[0141] There are two comparison items, which are divided into comparative examples and examples. The comparative example represents the average nickel content and cobalt recovery rate of the supernatant measured in June by adopting a conventional nickel removal method, that is, regularly sending a batch of clean slag after the second stage purification to the Aolu furnace for smelting treatment. The example represents the average nickel content and cobalt recovery rate of the supernatant measured by adopting the method of the embodiment of the present invention, that is, using a cobalt removal agent to remove cobalt while removing nickel. The example includes the test results in November and December.

[0142] Table 4 is a comparison and result of the average nickel content of the supernatant measured in the examples of the present invention and the comparative examples;

[0143] Table 4

[0144] Comparison Items month Average nickel content in supernatant (mg / L) Cobalt recovery rate (%) Before optimization June 62 91 After optimization November 18 90 December 21 92

[0145] According to Table 4, the treatment method of removing cobalt using a cobalt removal agent in this embodiment achieves the effect of removing nickel while removing cobalt. The average nickel content in the supernatant in mid-November is 18 mg / L, a decrease of 44 mg / L compared with June. The average nickel content in the supernatant in mid-December is 21 mg / L, a decrease of 41 mg / L compared with June, indicating that the method provided in this embodiment has certain feasibility and provides experimental data that can confirm that the above method can deeply remove cobalt and nickel.

[0146] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for deep removal of nickel and cobalt from wastewater, characterized in that: include, Step S1, collecting the comprehensive recovery cadmium-rich liquid at the water outlet of the comprehensive recovery workshop, sampling and monitoring the comprehensive recovery cadmium-rich liquid to obtain the initial cobalt content, the initial nickel content, the initial iron content and the initial cadmium content; Step S2, calculating the total amount of zinc powder added according to the initial cadmium content, adding zinc powder to the comprehensive recovery cadmium-rich solution with the total amount of zinc powder added, stirring and reacting for 30 minutes under the first water bath temperature condition, filtering the liquid with suction, the filtrate is a cadmium-poor liquid, and the filter residue is a sponge cadmium, determining the first actual content of zinc, cadmium, cobalt, nickel, and iron in the filtrate, and calculating the total amount of cobalt removal agent added according to the first actual content; Step S3, taking the cadmium-depleted solution, adding an activator under the second water bath temperature condition, stirring the reaction for 10 minutes, and then slurrying a corresponding mass of a cobalt removal agent at a preset addition rate to form a mixed solution, and monitoring the process of adding the cobalt removal agent to the mixed solution in real time until it is determined that the cobalt-nickel removal process is completed, obtaining a purified liquid and filtering it, obtaining a filtrate as a cobalt-removed liquid, and a filter residue as a cobalt removal agent residue; The uniformity of the mixed solution is analyzed according to the detection data of each arranged sampling point, and when the mixed solution is determined to be non-uniform, the real-time rotation speed variation is determined to control the stirring paddle to extend at a standard displacement distance, or to analyze whether the stirring state is abnormal; The process of real-time monitoring the addition of the cobalt removal agent to the mixed solution comprises: The real-time content difference corresponding to each sampling point is sequentially obtained in a preset monitoring period, the maximum content difference is calculated according to the real-time content difference, the standard content difference is compared with the maximum content difference, and whether the mixed solution is uniform is analyzed according to the comparison result; When it is determined that the mixed solution is not uniform, the real-time speed variation is obtained, and the real-time speed variation is determined according to the standard speed variation to control the extension of the stirring paddle or obtain the analysis point; Analyze the position of the analysis point, and determine whether the stirring is abnormal according to the analysis result; When there is no abnormality in stirring, adjust the preset addition speed; Obtaining the cobalt content of the mixed solution at any sampling point at a preset sampling interval, drawing a curve of the cobalt content of the mixed solution over time, analyzing the curve, and determining whether the cobalt-nickel removal process is completed according to the analysis result; Analyzing whether the mixed solution is uniform according to the comparison result includes: When the maximum content difference is less than or equal to the standard content difference, the mixed solution is determined to be uniform; When the maximum content difference is greater than the standard content difference, the mixed solution is determined to be non-uniform, the real-time stirring speed and the preset stirring speed are obtained, and the absolute value of the difference between the real-time stirring speed and the preset stirring speed is calculated to obtain the real-time rotation speed variation; Step S4, performing pickling treatment on the cobalt slag to obtain pickling solution and cobalt slag; When determining that the mixed solution is not uniform, determining the real-time speed variation according to the standard speed variation includes: When the real-time speed variation is less than or equal to the standard speed variation, the stirring paddle is controlled to extend at the standard displacement distance; When the real-time speed variation is greater than the standard speed variation, the collection point corresponding to the maximum content difference is obtained to obtain the analysis point, the position of the analysis point is analyzed, and whether the stirring is abnormal is determined according to the analysis result; Among them, the standard displacement distance is 1 / 5 of the distance between the stirring paddle and the tank bottom; When the real-time speed variation is greater than the standard speed variation, analyzing the position of the analysis point includes: If the analysis point is in the bottom area, it is determined that the stirring is normal, the preset addition speed is adjusted to a corrected addition speed, and the cobalt removal agent is added to the solution at the preset addition speed; If the analysis point is located in a non-bottom area, it is determined that the stirring is abnormal, and the preset stirring speed is adjusted to a corrected stirring speed; Among them, Uc'=Uc×[1+(ΔQs-ΔQb) / ΔQs], Vc'=Vc×[1+(ΔQs-ΔQb) / ΔQs], Uc' is the corrected addition speed, Uc is the preset addition speed, Vc' is the corrected stirring speed, Vc is the preset stirring speed, ΔQs is the real-time speed deviation, and ΔQb is the standard speed deviation.

2. The method for deep removal of nickel and cobalt from wastewater according to claim 1, characterized in that: Analyzing the change curve includes: Obtain the slope of the line segment between any adjacent sampling points for determination. When the slope is less than or equal to zero, continue to obtain the real-time content difference corresponding to each sampling point in the next preset monitoring period for analysis and determination; When the slope is greater than zero, the standard reaction time is obtained, and it is determined that the cobalt-nickel removal process is completed.

3. The method for deep removal of nickel and cobalt from wastewater according to claim 1, characterized in that: Calculating the maximum content difference based on the real-time content difference includes: The reaction tank is divided into a number of equally spaced areas using a straight line parallel to the tank bottom to obtain corresponding monitoring area units; For any of the monitoring area units, respectively obtain the real-time cobalt content collected at each sampling point, and calculate the average cobalt content of the monitoring area unit as the unit cobalt content; Add the cobalt content of each unit and divide it by the number of units in the monitoring area to obtain the real-time cobalt content of the reaction tank; Subtract the cobalt content of each unit from the real-time cobalt content to obtain the difference of cobalt content of several units; The absolute value of the cobalt content difference of each unit is taken, and the maximum value among the absolute values ​​is obtained as the maximum content difference of the reaction tank.

4. The method for deep removal of nickel and cobalt from wastewater according to claim 1, characterized in that: The total amount of zinc powder added is 0.9 times the initial cadmium content, and the first water bath temperature condition is a constant water bath temperature of 45-50°C.

5. The method for deep removal of nickel and cobalt from wastewater according to claim 1, characterized in that: The total amount of the cobalt removal agent added is 5-10 times the sum of the mass of cobalt and nickel, or 4-8 times the sum of the mass of cadmium and iron; the amount of the activator added is one tenth of the amount of the cobalt removal agent added; The cobalt removal agent is sodium dimethyldithiocarbamate.

6. The method for deep removal of nickel and cobalt from wastewater according to claim 1, characterized in that: The process of pickling treatment is as follows: Add sulfuric acid solution to the cobalt removal agent slag under preset pickling conditions for pickling, keep the water bath at a constant temperature of 75-80° C., stir and react for 60 minutes, and then filter the liquid to obtain a pickling solution and cobalt slag; Among them, the preset pickling conditions are the initial acid sulfuric acid concentration and the liquid-solid ratio. The initial acid sulfuric acid concentration is between 100g / L-200g / L, and the liquid-solid ratio is 5:1.

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