Method for removing TOC in zinc sulfate solution and application

Abstract

The invention belongs to the technical field of zinc hydrometallurgy, and particularly relates to a method for removing TOC in a zinc sulfate solution and application. The method for removing TOC in the zinc sulfate solution comprises the following steps: mixing the zinc sulfate solution with pulpified coal-based activated carbon, carrying out primary adsorption, and carrying out solid-liquid separation on the adsorbed zinc sulfate solution to obtain supernate; and mixing the supernate with pulpified wooden activated carbon, carrying out secondary adsorption, and carrying out solid-liquid separation on the zinc sulfate solution after adsorption. According to the method, specific types of coal-based activated carbon and wood-based activated carbon are selected, a specific adding sequence is adopted, namely, the coal-based activated carbon is firstly adopted, and then the wood-based activated carbon is adopted, so that the TOC content in the zinc sulfate solution can be reduced from 170-260 mg / L to 70-85 mg / L, the removal rate can reach 69.83%, zinc electrolysis production can be stabilized, the current efficiency can be improved, and the production cost can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgical zinc smelting, and particularly relates to a method for removing TOC in zinc sulfate solution and its application. Background Art

[0002] Hydrometallurgical zinc smelting is an efficient and clean zinc smelting process, which has been widely applied in the global zinc industry. This process leaches zinc ore with sulfuric acid to obtain a high-concentration zinc sulfate solution, and then produces high-purity metallic zinc through solution purification and electrolytic deposition steps. However, the presence of impurities in the zinc sulfate solution, especially total organic carbon (TOC), poses many challenges to the electrolysis process and the purity of the final zinc product. TOC mainly comes from residual natural organic matter in raw materials, additives in the leaching reaction, and externally introduced organic pollutants. Its accumulation in the solution may lead to a significant decrease in electrolysis efficiency, a reduction in current efficiency, and uneven cathode zinc deposition. To ensure the stability of the hydrometallurgical zinc smelting process and the quality of zinc products, it is particularly crucial to develop an efficient TOC removal technology.

[0003] Currently, in actual industrial applications, there are still technical bottlenecks in the removal of TOC. Especially under the premise of considering environmental friendliness and economic feasibility, the removal rate of TOC is still relatively low.

[0004] Therefore, it is of great significance to provide a method for removing TOC in zinc sulfate solution with a high TOC removal rate. Summary of the Invention

[0005] The present invention aims to solve one or more of the above-mentioned technical problems existing in the prior art, and at least provides a beneficial option. Specifically, the present invention provides a method for removing TOC in zinc sulfate solution, which has a high TOC removal rate.

[0006] The inventive concept of the present invention: The method for removing TOC in zinc sulfate solution of the present invention includes the following steps: (1) Mix the zinc sulfate solution and slurried coal-based activated carbon for primary adsorption, and perform solid-liquid separation on the adsorbed zinc sulfate solution to obtain a supernatant; (2) Mix the supernatant obtained in step (1) and slurried wood-based activated carbon for secondary adsorption, and perform solid-liquid separation on the adsorbed zinc sulfate solution. The present invention selects a specific type of activated carbon according to the treatment conditions of zinc sulfate at different stages, and removes TOC in the zinc sulfate solution through a specific addition sequence, with a high removal rate.

[0007] Therefore, in the first aspect of the present invention, a method for removing TOC in zinc sulfate solution is provided.

[0008] Specifically, the method for removing TOC in the zinc sulfate solution includes the following steps:

[0009] (1) Mix the zinc sulfate solution and the slurried coal-based activated carbon for primary adsorption, and perform solid-liquid separation on the adsorbed zinc sulfate solution to obtain the supernatant.

[0010] (2) Mix the supernatant obtained in step (1) and the slurried wood-based activated carbon for secondary adsorption, and perform solid-liquid separation on the adsorbed zinc sulfate solution.

[0011] Specifically, step (1) is the iron removal stage in zinc hydrometallurgy, and step (2) is the purification stage in zinc hydrometallurgy.

[0012] Preferably, in step (1), the concentration of TOC in the zinc sulfate solution is 170 - 260 mg / L; more preferably, the concentration of TOC in the zinc sulfate solution is 180 - 250 mg / L.

[0013] Preferably, in step (1), the preparation process of the slurried coal-based activated carbon is to mix the solvent with the coal-based activated carbon to obtain the slurried coal-based activated carbon.

[0014] Preferably, the specific surface area of the coal-based activated carbon is 800 - 1200 m 2 / g, more preferably, the specific surface area of the coal-based activated carbon is 900 - 1100 m 2 / g.

[0015] Preferably, the iodine adsorption value of the coal-based activated carbon is 800 - 1100 mg / g; more preferably, the iodine adsorption value of the coal-based activated carbon is 900 - 1000 mg / g.

[0016] Specifically, the above parameters are the parameters of the coal-based activated carbon after crushing.

[0017] Specifically, the coal-based activated carbon is mainly composed of micropores and also has mesopores. It has a strong adsorption capacity for hydrophobic and non-polar organic substances, a relatively high saturated adsorption capacity, a relatively slow adsorption rate, is suitable for deep treatment and long-term contact scenarios, has high mechanical strength and is wear-resistant. According to the time requirement of the iron removal stage, the coal-based activated carbon is suitable for long-term primary adsorption of non-polar organic substances.

[0018] Preferably, the liquid-solid ratio of the solvent to the coal-based activated carbon is (2.7 - 4.5):1; more preferably, the liquid-solid ratio of the solvent to the coal-based activated carbon is (3 - 4):1.

[0019] Preferably, the solvent includes water.

[0020] Preferably, the temperature during mixing is room temperature.

[0021] Preferably, the mixing is carried out by stirring, and the stirring time is 18 - 33 min; more preferably, the stirring time is 20 - 30 min.

[0022] Preferably, in step (1), the mixing is carried out in a low - iron reaction tank, and the residence time of the zinc sulfate solution in the low - iron reaction tank is 35 - 55 min; more preferably, the residence time of the zinc sulfate solution in the low - iron reaction tank is 40 - 50 min.

[0023] Preferably, in step (1), the addition amount of the slurried coal - based activated carbon is 4.5 - 11 times the total TOC amount in the zinc sulfate solution; more preferably, the addition amount of the slurried coal - based activated carbon is 5 - 10 times the total TOC amount in the zinc sulfate solution.

[0024] Preferably, the total TOC amount = current flow rate of zinc sulfate × residence time of zinc sulfate solution in the low - iron reaction tank × TOC concentration in the zinc sulfate solution.

[0025] Preferably, in step (1), the temperature of the first - stage adsorption is 60 - 80 °C; more preferably, the temperature of the first - stage adsorption is 65 - 75 °C.

[0026] Preferably, in step (1), the pH of the first - stage adsorption is 4.0 - 6.0; more preferably, the pH of the first - stage adsorption is 4.5 - 5.5.

[0027] Specifically, in step (1), the time of the first - stage adsorption is the residence time of the zinc sulfate solution in the low - iron reaction tank.

[0028] Preferably, in step (1), the adsorbed zinc sulfate solution enters a thickener for clarification and solid - liquid separation, and the residence time of the adsorbed zinc sulfate solution in the thickener is 5.5 - 8.5 h; more preferably, the residence time of the adsorbed zinc sulfate solution in the thickener is 6 - 8 h.

[0029] Preferably, in step (1), the supernatant after solid - liquid separation is sent to the next purification process, and the bottom slag and part of the solution are returned to the iron - removal process.

[0030] Preferably, in step (2), the dosage ratio of the slurried wood - based activated carbon to the supernatant is (0.1 - 0.33) kg:1 m 3 ; more preferably, in step (2), the dosage ratio of the slurried wood - based activated carbon to the supernatant is (0.1 - 0.3) kg:1 m 3 .

[0031] Preferably, the preparation process of the slurried wood-based activated carbon is to mix a solvent with the wood-based activated carbon to obtain the slurried wood-based activated carbon.

[0032] Preferably, the specific surface area of the wood-based activated carbon is 720 - 1100 m 2 / g.

[0033] More preferably, the specific surface area of the wood-based activated carbon is 800 - 1000 m 2 / g.

[0034] Preferably, the iodine adsorption value of the wood-based activated carbon is 1000 - 1300 mg / g.

[0035] More preferably, the iodine adsorption value of the wood-based activated carbon is 1100 - 1200 mg / g.

[0036] Specifically, the above parameters are those of the wood-based activated carbon after crushing.

[0037] Specifically, the wood-based activated carbon mainly consists of mesopores and macropores, which is suitable for adsorbing organic compounds with larger molecules. The surface is rich in oxygen-containing groups, and has good adsorption performance for water-soluble, polar or hydrophilic organic compounds (such as phenols, alcohols), and the adsorption rate is usually fast. Compared with coal-based activated carbon, the wood-based activated carbon has more obvious adsorption of polar and water-soluble organic pollutants, and relatively weak adsorption effect on non-polar organic compounds (such as oils, solvents). According to the time requirement of primary purification, the wood-based activated carbon is suitable for short-term secondary adsorption of polar organic compounds.

[0038] Preferably, the liquid-solid ratio of the solvent to the wood-based activated carbon is (2.7 - 4.5):1; more preferably, the liquid-solid ratio of the solvent to the coal-based activated carbon is (3 - 4):1.

[0039] Preferably, the solvent includes water.

[0040] Preferably, in step (2), the mixing is carried out in a primary purification reaction tank, and the residence time of the supernatant in the primary purification reaction tank is 22.5 - 32.5 min; more preferably, the residence time of the supernatant in the primary purification reaction tank is 25 - 30 min.

[0041] Preferably, the current supernatant volume = the current supernatant flow rate × the residence time of the supernatant in the primary purification reaction tank.

[0042] Preferably, in step (2), the temperature of the secondary adsorption is 72 - 95 °C; more preferably, the temperature of the secondary adsorption is 80 - 90 °C.

[0043] Preferably, in step (2), the pH of the secondary adsorption is 4.0 - 5.5; more preferably, the pH of the secondary adsorption is 4.5 - 5.0.

[0044] Specifically, in step (2), the time of the secondary adsorption is the residence time of the supernatant in the primary purification reaction tank.

[0045] Preferably, in step (2), the solid-liquid separation is carried out by pressure filtration.

[0046] Preferably, an automatic filter press is used for solid-liquid separation, the filtrate is sent to the secondary purification, and the filter cake is collected and then sent to the warehouse for storage or sale.

[0047] The second aspect of the present invention provides an application of the method for removing TOC in the zinc sulfate solution described in the first aspect of the present invention in the field of hydrometallurgical zinc smelting.

[0048] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0049] (1) Without adding an additional oxidant, according to the treatment conditions of zinc sulfate at different stages, the present invention selects a specific type of activated carbon and through a specific addition sequence, can reduce the TOC content in the zinc sulfate solution from 170 - 260 mg / L to 70 - 85 mg / L, and the removal rate can reach 60 - 70%. With a high removal rate, the TOC in the zinc sulfate solution is removed by a simple and low-cost method, thereby stabilizing zinc electrolysis production, improving current efficiency, and reducing production costs.

[0050] (2) The process flow of the present invention is simple and is convenient for large-scale production applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a process flow schematic diagram of the method for removing TOC in the zinc sulfate solution in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0052] In order to make those skilled in the art more clearly understand the technical solution described in the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention.

[0053] The raw materials, reagents or devices used in the following examples can be obtained from conventional commercial channels or can be obtained by existing known methods without special instructions.

[0054] Example 1

[0055] A method for removing TOC in a zinc sulfate solution, comprising the following steps:

[0056] (1) Iron removal stage in zinc hydrometallurgy: The flow rate of zinc sulfate solution is 160 m 3 / h, the TOC content is 234 mg / L. It is placed in a low-iron reaction tank and mixed with well-slurried coal-based activated carbon. 157.875 kg of well-slurried coal-based activated carbon is added according to 5 times the total amount of TOC. The total amount of TOC is 31.575 kg ((0.75×160×1000)×234÷1000000 = 31.575 kg). Using the stirring effect of the reaction tank for primary adsorption, the temperature of primary adsorption is 65 °C, pH is 4.5, and the time is 45 min. After adsorption, the solution flows by gravity to the thickener and stays in the thickener for 6 h for clarification and liquid-solid separation. The supernatant flows to the next stage. The supernatant is filtered by suction and the TOC content is detected to be 105 mg / L. The TOC removal rate of coal-based activated carbon in primary adsorption is 55.13% (55.13% = (234 - 105) / 234×100%). The bottom slag and part of the solution are returned to the high-iron reaction tank in the iron removal process;

[0057] (2) Purification stage in zinc hydrometallurgy: The supernatant obtained in step (1) is transported to a primary purification reaction tank. Continuing according to the process conditions of on-site primary purification, well-slurried wood-based activated carbon is transported to the primary purification reaction tank by belt. The well-slurried wood-based activated carbon is added at a ratio of 0.1 kg / m 3 . The flow rate of the supernatant remains 160 m 3 / h, and the amount of supernatant to be treated is 60 m 3 . The amount of wood-based activated carbon added according to the ratio is 6 kg for secondary adsorption. The temperature of secondary adsorption is 85 °C, pH is 4.5, and the time is 22.5 min. After secondary adsorption, the zinc sulfate solution enters an automatic filter press for liquid-solid separation to obtain a zinc sulfate solution with a low TOC concentration. The filter residue is collected and sent out of the process. The filtrate after liquid-solid separation is filtered by suction, and the TOC content is detected to be 85 mg / L. After secondary adsorption by wood-based activated carbon, the total TOC removal rate is 63.68% (63.68% = (234 - 85) / 234×100%).

[0058] Among them, in step (1), the slurrying process of coal-based activated carbon is as follows: Under normal temperature conditions, water and coal-based activated carbon are mixed at a liquid-solid ratio of 3.5:1 and stirred for 25 min to complete.

[0059] In step (2), the slurrying process of wood-based activated carbon is as follows: Under normal temperature conditions, water and wood-based activated carbon are mixed at a liquid-solid ratio of 3.5:1 and stirred for 25 min to complete.

[0060] The process flow diagram of the method for removing TOC in zinc sulfate solution in Example 1 is as shown in Figure 1 shown.

[0061] Example 2

[0062] A method for removing TOC from zinc sulfate solution, comprising the following steps:

[0063] (1) In the iron removal stage of hydrometallurgical zinc smelting: The flow rate of the zinc sulfate solution is 160 m 3 / h, the TOC content is 227 mg / L. It is placed in a low-iron reaction tank and mixed with slurried coal-based activated carbon. 163.44 kg of slurried coal-based activated carbon is added according to 6 times the total amount of TOC. The total amount of TOC is 27.24 kg ((0.75×160×1000)×227÷1000000 = 27.24 kg). Using the stirring action of the reaction tank for primary adsorption, the temperature of the primary adsorption is 70 °C, the pH is 4.5, and the time is 45 min. After adsorption, the solution flows by gravity to the thickener and stays in the thickener for 6 h for clarification and liquid-solid separation. The supernatant flows to the next stage. The supernatant is filtered by suction to detect the TOC content of 103 mg / L. The TOC removal rate of the coal-based activated carbon in primary adsorption is 54.62% (54.62% = (227 - 103) / 227×100%). The bottom slag and part of the solution are returned to the high-iron reaction tank of the iron removal process;

[0064] (2) In the purification stage of hydrometallurgical zinc smelting: The supernatant obtained in step (1) is transported to a primary purification reaction tank, and slurried wood-based activated carbon is continuously added according to the process conditions of on-site primary purification. The slurried wood-based activated carbon is added at a ratio of 0.3 kg / m 3 of the treatment volume. The flow rate of the supernatant is maintained at 160 m 3 / h, and the volume of the supernatant to be treated is 60 m 3 . 18 kg of wood-based activated carbon is added according to the ratio for secondary adsorption. The temperature of the secondary adsorption is 85 °C, the pH is 4.5, and the time is 22.5 min. After the secondary adsorption, the zinc sulfate solution enters an automatic filter press for liquid-solid separation to obtain a zinc sulfate solution with a low TOC concentration. The filter residue is collected and sent out of the process. The filtrate after liquid-solid separation is filtered by suction to detect the TOC content of 70 mg / L. After the secondary adsorption by the wood-based activated carbon, the total TOC removal rate is 69.16% (69.16% = (227 - 70) / 227×100%).

[0065] Among them, the slurrying processes of the coal-based activated carbon and the wood-based activated carbon are the same as those in Example 1.

[0066] Example 3

[0067] A method for removing TOC from zinc sulfate solution, comprising the following steps:

[0068] (1) In the iron removal stage of hydrometallurgical zinc smelting: The flow rate of the zinc sulfate solution is 160 m 3 / h, with a TOC content of 219 mg / L, placed in a low-iron reaction tank, and mixed with slurried coal-based activated carbon. 157.68 kg of slurried coal-based activated carbon is added according to 6 times the total amount of TOC. The total amount of TOC is 26.28 kg ((0.75×160×1000)×219÷1000000 = 26.28 kg). Using the stirring action of the reaction tank for primary adsorption, the temperature of primary adsorption is 70 °C, the pH is 4.8, and the time is 45 min. After adsorption, the solution flows by gravity to the thickener, stays in the thickener for 6 h for clarification and liquid-solid separation. The supernatant flows to the next stage. The TOC content of the supernatant is detected by suction filtration to be 103 mg / L. The TOC removal rate of the coal-based activated carbon in primary adsorption is 52.97% (52.97% = (219 - 103) / 219×100%). The bottom slag and part of the solution are returned to the high-iron reaction tank in the iron removal process;

[0069] (2) In the purification stage of hydrometallurgical zinc smelting: The supernatant obtained in step (1) is transported to a primary purification reaction tank, and slurried wood-based activated carbon is continuously added according to the process conditions of on-site primary purification. The slurried wood-based activated carbon is added at a ratio of 0.3 kg / m 3 . The flow rate of the supernatant is maintained at 160 m 3 / h, and the amount of supernatant treated is 60 m 3 . 18 kg of wood-based activated carbon is added according to the ratio for secondary adsorption. The temperature of secondary adsorption is 85 °C, the pH is 4.5, and the time is 22.5 min. After secondary adsorption, the zinc sulfate solution enters an automatic filter press for liquid-solid separation to obtain a zinc sulfate solution with a low TOC concentration. The filter residue is collected and sent out of the system. The filtrate after liquid-solid separation is suction filtered, and the TOC content is detected to be 83 mg / L. After secondary adsorption by the wood-based activated carbon, the total TOC removal rate is 62.10% (62.10% = (219 - 83) / 219×100%).

[0070] Among them, the slurrying processes of the coal-based activated carbon and the wood-based activated carbon are the same as those in Example 1.

[0071] Example 4

[0072] A method for removing TOC in zinc sulfate solution, comprising the following steps:

[0073] (1) In the iron removal stage of hydrometallurgical zinc smelting: The flow rate of the zinc sulfate solution is 160 m 3 / h, with a TOC content of 232 mg / L, placed in a low-iron reaction tank, and mixed with slurried coal-based activated carbon. 278.4 kg of slurried coal-based activated carbon is added according to 10 times the total amount of TOC. The total amount of TOC is 27.84 kg ((0.75×160×1000)×232÷1000000 = 27.84 kg). The first-stage adsorption is carried out using the stirring function of the reaction tank. The temperature of the first-stage adsorption is 65 °C, the pH is 4.5, and the time is 45 min. After adsorption, the solution flows by gravity to the thickener, stays in the thickener for 6 h for clarification and liquid-solid separation. The supernatant flows to the next stage. The TOC content of the supernatant is detected by suction filtration to be 99 mg / L. The TOC removal rate of the coal-based activated carbon in the first-stage adsorption is 57.32% (57.32% = (232 - 99) / 232×100%). The bottom slag and part of the solution are returned to the high-iron reaction tank in the iron removal process;

[0074] (2) Purification stage of hydrometallurgical zinc smelting: The supernatant obtained in step (1) is transported to a primary purification reaction tank, and slurried wood-based activated carbon is continuously added according to the process conditions of on-site primary purification. The slurried wood-based activated carbon is added at a ratio of 0.3 kg / m 3 The flow rate of the supernatant is maintained at 160 m 3 / h, and the amount of supernatant to be treated is 60 m 3 . 18 kg of wood-based activated carbon is added according to the ratio for the second-stage adsorption. The temperature of the second-stage adsorption is 85 °C, the pH is 4.5, and the time is 22.5 min. After the second-stage adsorption, the zinc sulfate solution enters an automatic filter press for liquid-solid separation to obtain a zinc sulfate solution with a low TOC concentration. The filter residue is collected and sent out of the process. The filtrate after liquid-solid separation is suction filtered, and the TOC content is detected to be 70 mg / L. After the second-stage adsorption by the wood-based activated carbon, the total TOC removal rate is 69.83% (69.83% = (232 - 70) / 232×100%).

[0075] Among them, the slurrying processes of the coal-based activated carbon and the wood-based activated carbon are the same as those in Example 1.

[0076] Comparative Example 1

[0077] The difference between the removal methods of Comparative Example 1 and Example 4 is only that in step (2) of Comparative Example 1, an equal amount of slurried coal-based activated carbon is used to replace the slurried wood-based activated carbon, and the others are the same as in Example 4.

[0078] In step (1) of Comparative Example 1, the TOC content of the supernatant is detected by suction filtration to be 99 mg / L, and the TOC removal rate of the coal-based activated carbon in the first-stage adsorption is 57.32%; in step (2), the TOC content is detected to be 95 mg / L, and the total TOC removal rate after the second-stage adsorption by the coal-based activated carbon is 59.05%.

[0079] Comparative Example 2

[0080] The difference between the removal methods of Comparative Example 2 and Example 4 is only that in step (1) of Comparative Example 2, an equal amount of slurried wood-based activated carbon is used to replace the slurried coal-based activated carbon, and the rest is the same as in Example 4.

[0081] In step (1) of Comparative Example 2, the TOC content of the supernatant was detected by suction filtration to be 96 mg / L, and the TOC removal rate by the first-stage adsorption of wood-based activated carbon was 54.33%; in step (2), the detected TOC content was 89 mg / L, and the total TOC removal rate after the second-stage adsorption by wood-based activated carbon was 61.64%.

[0082] Comparative Example 3

[0083] The difference between the removal methods of Comparative Example 3 and Example 4 is only that in step (1) of Comparative Example 3, an equal amount of slurried wood-based activated carbon is used to replace the coal-based activated carbon; in step (2), an equal amount of slurried coal-based activated carbon is used to replace the wood-based activated carbon, that is, the addition order of the wood-based activated carbon and the coal-based activated carbon is adjusted, and the rest is the same as in Example 4.

[0084] In step (1) of Comparative Example 3, the TOC content of the supernatant was detected by suction filtration to be 96 mg / L, and the TOC removal rate by the first-stage adsorption of wood-based activated carbon was 54.33%; in step (2), the detected TOC content was 92 mg / L, and the total TOC removal rate after the second-stage adsorption by coal-based activated carbon was 60.34%.

[0085] It can be seen from Comparative Examples 1-3 that in Comparative Example 1, only coal-based activated carbon was used. When coal-based activated carbon was used for secondary adsorption during the first-stage purification, the improvement of the overall TOC removal rate was not significant. Because after the first-stage adsorption of coal-based activated carbon, most of the small and medium molecules and non-polar organic substances in the zinc sulfate solution had been adsorbed. When coal-based activated carbon was added for secondary adsorption, the adsorption rate of the large molecules and polar organic substances in the zinc sulfate solution was not high, resulting in poor overall TOC removal rate.

[0086] In Comparative Example 2, only wood-based activated carbon was used, and the TOC removal rate was relatively low. This is because the wood-based activated carbon has strong adsorption ability for large molecules and polar organic substances, general adsorption effect on small and medium molecules of organic substances, and poor adsorption ability for non-polar organic substances. After the second-stage adsorption of wood-based activated carbon, there are still residues of non-polar organic substances in the zinc sulfate solution, resulting in poor overall TOC removal rate. In addition, from an economic point of view, using wood-based activated carbon for both the first-stage and second-stage adsorption will increase the cost.

[0087] In Comparative Example 3, wood-based activated carbon was first used and then coal-based activated carbon. Wood-based activated carbon was used for primary adsorption in the iron removal stage, and coal-based activated carbon was used in the primary purification stage. The improvement in the removal rate of the overall TOC was not significant. This is because the action time of coal-based activated carbon for organic matter adsorption is long, while the reaction time in the primary purification stage is fast, which is not conducive to the adsorption of coal-based activated carbon, resulting in poor removal effect of the overall TOC.

[0088] In summary, the present invention selects specific types of coal-based activated carbon and wood-based activated carbon, and adopts a specific addition sequence, that is, coal-based activated carbon is used first and then wood-based activated carbon, which can reduce the TOC content in the zinc sulfate solution from 170 - 260 mg / L to 70 - 85 mg / L, and the removal rate can reach 69.83%. The removal rate is high, and the TOC in the zinc sulfate solution is removed by a simple and low-cost method.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for removing TOC from zinc sulfate solution, characterized in that, It includes the following steps: (1) Mix a zinc sulfate solution with slurried coal-based activated carbon for primary adsorption, and perform solid-liquid separation on the adsorbed zinc sulfate solution to obtain a supernatant; (2) Mix the supernatant obtained in step (1) with slurried wood-based activated carbon for secondary adsorption, and perform solid-liquid separation on the adsorbed zinc sulfate solution.

2. The removal method according to claim 1, wherein In step (1), the content of TOC in the zinc sulfate solution is 170 - 260 mg / L; and / or, the preparation process of the slurried coal-based activated carbon is to mix a solvent with the coal-based activated carbon to obtain the slurried coal-based activated carbon.

3. The removal method according to claim 2, characterized in that, The specific surface area of the coal-based activated carbon is 800-1200 m 2 / g; and / or, the iodine adsorption value of the coal-based activated carbon is 800-1100 mg / g; and / or, the liquid-solid ratio of the solvent to the coal-based activated carbon is (2.7-4.5):1; and / or, mixing is carried out by stirring, and the stirring time is 18-33 min.

4. The removal method according to claim 1, characterized in that, In step (1), the addition amount of the slurried coal-based activated carbon is 4.5 - 11 times the total amount of TOC in the zinc sulfate solution; and / or, the temperature of the primary adsorption is 60 - 80 °C; and / or, the pH of the primary adsorption is 4.0 - 6.

0.

5. The removal method according to claim 1, characterized in that, The mixing is carried out in a low-iron reaction tank, and the residence time of the zinc sulfate solution in the low-iron reaction tank is 35 - 55 min; and / or, the adsorbed zinc sulfate solution enters a thickener for clarification and solid-liquid separation, and the residence time of the adsorbed zinc sulfate solution in the thickener is 5.5 - 8.5 h.

6. The removal method according to claim 1, wherein In step (2), the dosage ratio of the pulped woody activated carbon to the supernatant obtained in step (1) is (0.1 - 0.33) kg: 1 m 3 .

7. The removal method according to claim 1, wherein The preparation process of the slurried wood-based activated carbon is to mix a solvent with the wood-based activated carbon to obtain the slurried wood-based activated carbon.

8. The removal method according to claim 7, characterized in that The specific surface area of the wood-based activated carbon is 720-1100 m 2 / g; and / or, the iodine adsorption value of the wood-based activated carbon is 1000-1300 mg / g; and / or, the liquid-solid ratio of the solvent to the wood-based activated carbon is (2.7-4.5):

1.

9. The removal method according to claim 1, wherein In step (2), the mixing is carried out in a primary purification reaction tank, and the residence time of the supernatant in the primary purification reaction tank is 22.5 - 32.5 min; and / or, the temperature of the secondary adsorption is 72 - 95 °C; and / or, the pH of the secondary adsorption is 4.0 - 5.5; and / or, the solid-liquid separation is carried out by pressure filtration.

10. Application of the removal method according to any one of claims 1 - 9 in the field of hydrometallurgical zinc smelting.

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