A new process for deep chlorine removal from electric zinc solution

Abstract

The present invention relates to the technical field of chlorine removal, and specifically discloses a new process for deep chlorine removal from electric zinc solution, which includes the following steps: Step 1: Add 20-30 parts of bismuth oxide modifier to 45-55 parts of concentrated sulfuric acid to form a compounding agent; Step 2: Subsequently, add 3-7 parts of modified nano-silica and continue to stir and mix thoroughly to obtain a modified liquid; Step 3: Add 10-20% of the total amount of the modified liquid to the liquid to be treated, stir thoroughly, and then perform solid-liquid separation. The modified liquid of the present invention can act synergistically with each other. By quantitatively adding this chloride ion modified liquid according to the chloride ion content, the chloride ions in the zinc sulfate solution can be completely removed, and no new impurities will be introduced into the system. Most importantly, after the modified liquid brings out the chloride ions, it can be regenerated by means of oxidation-reduction and can be used for chlorine removal infinitely and repeatedly.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic zinc solution, and particularly relates to a new process for deep chlorine removal from electrolytic zinc solution. Background Art

[0002] When producing electrolytic zinc with zinc oxide as raw material, in the traditional purification process of electrolytic zinc solution, first, most of the chloride ions are removed by alkali washing, and then leaching is carried out to obtain zinc sulfate solution. At this time, there are still about 1 - 2 grams per liter of chloride ions in the zinc sulfate solution, and this part of chloride ions is usually removed by anion resin exchange. The main disadvantage of this method is that during the resin regeneration process, a large amount of zinc-containing waste acid will be generated. To recover this part of zinc and achieve the discharge pH value, a large amount of lime is required, and at the same time, a large amount of zinc-containing waste solids are generated. The waste solids are generally roasted in a rotary kiln to recover zinc, which requires a large amount of energy consumption. Based on this, the present invention provides a new process for deep chlorine removal from electrolytic zinc solution. Summary of the Invention

[0003] Aiming at the defects of the prior art, the purpose of the present invention is to provide a new process for deep chlorine removal from electrolytic zinc solution to solve the problems mentioned in the above background art.

[0004] The present invention adopts the following technical solutions to solve the technical problems:

[0005] The present invention provides a new process for deep chlorine removal from electrolytic zinc solution, including the following steps:

[0006] Step 1: Add 20 - 30 parts of bismuth oxide modifier to 45 - 55 parts of concentrated sulfuric acid to form a compounding agent;

[0007] Step 2: Then add 3 - 7 parts of modified nano-silica dioxide, and continue to stir and mix thoroughly to obtain a modified liquid;

[0008] Step 3: Add 10 - 20% of the total amount of the modified liquid to the liquid to be treated, stir thoroughly, and then carry out solid-liquid separation;

[0009] Step 4: Add 20 - 30% of the total amount of sodium sulfite solution to the solid-liquid separation product of Step 2, and treat for 1 - 2 hours.

[0010] Preferably, the preparation method of the bismuth oxide modifier is as follows:

[0011] S01: Add bismuth oxide to a sodium alginate solution with a mass fraction of 20 - 30% that is 2 - 3 times the amount, then add hydrochloric acid accounting for 5 - 10% of the total amount of bismuth oxide, and then add cetyltrimethoxysilane accounting for 1 - 5% of the total amount of bismuth oxide, stir and react thoroughly, and set aside;

[0012] S02: Add 10-20% of sodium alkyl sulfonate and 2-5% of chitosan treatment agent to S01, continue to stir thoroughly, then wash with water and dry to obtain the bismuth oxide modifier.

[0013] Preferably, the preparation method of the chitosan treatment agent is as follows:

[0014] S101: Add 5-10 parts of chitosan to 10-15 parts of deionized water, then add 2-5 parts of phosphate buffer solution, and stir evenly;

[0015] S102: Then add 1-5 parts of lanthanum sulfate to the product of S101, and continue to mix thoroughly to obtain the chitosan treatment agent.

[0016] Preferably, the stirring reaction speed of S01 is 500-1000 r / min, and the stirring time is 20-30 min.

[0017] Preferably, the stirring speed of S02 is 1000-1200 r / min, and the stirring time is 30-40 min.

[0018] Preferably, the pH value of the phosphate buffer solution is 5.5.

[0019] Preferably, the preparation method of the modified nano-silica is as follows:

[0020] S11: Feed the nano-silica into 2-3 times of hydrochloric acid solution and stir to disperse evenly, then add 5-10% of 2-hydroxyethylamine based on the total amount of nano-silica, and continue to mix thoroughly;

[0021] S12: Finally, wash with water and dry, then add a grinding aid and grind in a grinder. After grinding, the modified nano-silica is obtained.

[0022] Preferably, the mass fraction of the hydrochloric acid solution is 10-15%; the grinding speed is 1000-1500 r / min, and the grinding time is 20-30 min.

[0023] Preferably, the grinding aid is prepared by stirring and mixing graphene, silica sol and deionized water according to a weight ratio of 3:1:5.

[0024] Preferably, the mass fraction of the sodium sulfite solution is 10-20%.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The modified liquid of the present invention can act synergistically with each other. By quantitatively adding this chloride ion modified liquid according to the chloride ion content, the chloride ions in the zinc sulfate solution can be completely removed, and no new impurities will be introduced into the system. Most importantly, after the modified liquid takes out the chloride ions, it can be regenerated by redox methods and can be used for chlorine removal infinitely and repeatedly. The advantage of this method is that no waste solids are generated and there is no need for rotary kiln roasting again, thus saving energy consumption. In addition, the amount of wastewater generated is very small. Compared with the traditional method, the amount of wastewater generated is less than one-tenth of the original. The treatment effect of chloride ions is enhanced by the synergistic cooperation of bismuth oxide modifier and modified nano-silica in the modified liquid. Detailed implementation mode

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0028] A new process for deep chlorine removal from electric zinc solution in this embodiment includes the following steps:

[0029] Step 1: Add 20 - 30 parts of bismuth oxide modifier to 45 - 55 parts of concentrated sulfuric acid to form a compounding agent.

[0030] Step 2: Subsequently, add 3 - 7 parts of modified nano-silica and continue to stir and mix thoroughly to obtain a modified liquid.

[0031] Step 3: Add 10 - 20% of the total amount of the modified liquid to the liquid to be treated, stir thoroughly, and then perform solid-liquid separation.

[0032] Step 4: Add 20 - 30% of the total amount of sodium sulfite solution to the solid-liquid separation product in Step 2 and treat for 1 - 2 hours.

[0033] The preparation method of the bismuth oxide modifier in this embodiment is as follows:

[0034] S01: Add bismuth oxide to a sodium alginate solution with a mass fraction of 20 - 30% that is 2 - 3 times the amount, then add hydrochloric acid accounting for 5 - 10% of the total amount of bismuth oxide, and then add cetyltrimethoxysilane accounting for 1 - 5% of the total amount of bismuth oxide, and stir and react thoroughly for standby.

[0035] S02: Add 10 - 20% of alkyl sulfonate and 2 - 5% of chitosan treatment agent to S01, continue to stir thoroughly, then wash with water and dry to obtain the bismuth oxide modifier.

[0036] The preparation method of the chitosan treatment agent in this embodiment is as follows:

[0037] S101: Add 5 - 10 parts of chitosan into 10 - 15 parts of deionized water, then add 2 - 5 parts of phosphate buffer solution, and stir evenly.

[0038] S102: Then add 1 - 5 parts of lanthanum sulfate to the product of S101, and continue to mix thoroughly to obtain the chitosan treatment agent.

[0039] The rotation speed of the stirring reaction in S01 of this example is 500 - 1000 r / min, and the stirring time is 20 - 30 min.

[0040] The rotation speed of the stirring in S02 of this example is 1000 - 1200 r / min, and the stirring time is 30 - 40 min.

[0041] The pH value of the phosphate buffer solution in this example is 5.5.

[0042] The preparation method of the modified nano - silica in this example is as follows:

[0043] S11: Feed the nano - silica into 2 - 3 times the hydrochloric acid solution and stir to disperse evenly, then add 2 - hydroxyethylamine accounting for 5 - 10% of the total amount of nano - silica, and continue to mix thoroughly.

[0044] S12: Finally, wash with water, dry, then add a grinding aid and grind in a grinder. After grinding, the modified nano - silica is obtained.

[0045] The mass fraction of the hydrochloric acid solution in this example is 10 - 15%; the rotation speed of the grinding treatment is 1000 - 1500 r / min, and the grinding time is 20 - 30 min.

[0046] The grinding aid in this example is prepared by stirring graphene, silica sol and deionized water in a weight ratio of 3:1:5.

[0047] The mass fraction of the sodium sulfite solution in this example is 10 - 20%.

[0048] Example 1.

[0049] A new process for deep chlorine removal from electric zinc solution in this example includes the following steps:

[0050] Step 1: Add 20 parts of bismuth oxide modifier into 45 parts of concentrated sulfuric acid to form a compounding agent.

[0051] Step 2: Then add 3 parts of modified nano - silica and continue to stir and mix thoroughly to obtain a modified liquid.

[0052] Step 3: Add 10% of the total amount of the modified liquid to the liquid to be treated, stir thoroughly, and then perform solid - liquid separation.

[0053] Step 4: Add a sodium sulfite solution accounting for 20% of the total amount to the solid-liquid separation product obtained in Step 2, and process for 1 h to complete.

[0054] The preparation method of the bismuth oxide modifier in this example is as follows:

[0055] S01: Add bismuth oxide to a sodium alginate solution with a mass fraction of 20% that is twice the amount, then add it to hydrochloric acid accounting for 5% of the total amount of bismuth oxide, and then add cetyltrimethoxysilane accounting for 1% of the total amount of bismuth oxide, and stir the reaction sufficiently for standby;

[0056] S02: Add 10% of alkyl sulfonate and 2% of chitosan treatment agent to S01, continue to stir sufficiently, then wash with water and dry to obtain the bismuth oxide modifier.

[0057] The preparation method of the chitosan treatment agent in this example is as follows:

[0058] S101: Add 5 parts of chitosan to 10 parts of deionized water, and then add 2 parts of phosphate buffer solution and stir evenly;

[0059] S102: Then add 1 part of lanthanum sulfate to the product of S101 and continue to mix sufficiently to obtain the chitosan treatment agent.

[0060] The rotation speed of the stirring reaction in S01 of this example is 500 r / min, and the stirring time is 20 min.

[0061] The rotation speed of the stirring in S02 of this example is 1000 r / min, and the stirring time is 30 min.

[0062] The pH value of the phosphate buffer solution in this example is 5.5.

[0063] The preparation method of the modified nano-silica in this example is as follows:

[0064] S11: Feed nano-silica into a hydrochloric acid solution that is twice the amount and stir to disperse evenly, then add 2-hydroxyethylamine accounting for 5% of the total amount of nano-silica and continue to mix sufficiently;

[0065] S12: Finally, wash with water and dry, then add a grinding aid and grind in a grinder. After the grinding is completed, the modified nano-silica is obtained.

[0066] The mass fraction of the hydrochloric acid solution in this example is 10%; the rotation speed of the grinding treatment is 1000 r / min, and the grinding time is 20 min.

[0067] The grinding aid in this example is prepared by stirring graphene, silica sol, and deionized water in a weight ratio of 3:1:5.

[0068] The mass fraction of the sodium sulfite solution in this embodiment is 10%.

[0069] Example 2.

[0070] A new process for deep chlorine removal from zinc electroplating solution in this embodiment includes the following steps:

[0071] Step 1: Add 30 parts of bismuth oxide modifier to 55 parts of concentrated sulfuric acid to form a compounding agent.

[0072] Step 2: Subsequently, add 7 parts of modified nano-silica dioxide and continue to stir and mix thoroughly to obtain a modified solution.

[0073] Step 3: Add 20% of the total amount of the modified solution to the solution to be treated, stir thoroughly, and then perform solid-liquid separation.

[0074] Step 4: Add 30% of the total amount of sodium sulfite solution to the solid-liquid separation product in Step 2 and treat for 2 h to complete.

[0075] The preparation method of the bismuth oxide modifier in this embodiment is as follows:

[0076] S01: Add bismuth oxide to 3 times the mass fraction of 30% sodium alginate solution, then add it to 10% of the total amount of bismuth oxide in hydrochloric acid, and then add 5% of the total amount of bismuth oxide in cetyltrimethoxysilane, stir and react thoroughly, and set aside.

[0077] S02: Add 20% of alkyl sulfonate and 5% of chitosan treatment agent to S01, continue to stir thoroughly, wash with water and dry to obtain the bismuth oxide modifier.

[0078] The preparation method of the chitosan treatment agent in this embodiment is as follows:

[0079] S101: Add 5 - 10 parts of chitosan to 15 parts of deionized water, then add 5 parts of phosphate buffer solution, and stir evenly.

[0080] S102: Then add 5 parts of lanthanum sulfate to the product of S101 and continue to mix thoroughly to obtain the chitosan treatment agent.

[0081] The stirring reaction speed of S01 in this embodiment is 1000 r / min, and the stirring time is 30 min.

[0082] The stirring speed of S02 in this embodiment is 1200 r / min, and the stirring time is 40 min.

[0083] The pH value of the phosphate buffer solution in this embodiment is 5.5.

[0084] The preparation method of the modified nano-silica dioxide in this embodiment is as follows:

[0085] S11: Feed nano-silica into 3 times the amount of hydrochloric acid solution and stir to disperse evenly. Then add 2-hydroxyethylamine accounting for 10% of the total amount of nano-silica and continue to mix thoroughly.

[0086] S12: Finally, wash with water and dry. Then add a grinding aid and grind in a grinder. After grinding, modified nano-silica is obtained.

[0087] In this example, the mass fraction of the hydrochloric acid solution is 15%; the rotation speed of the grinding process is 1500 r / min and the grinding time is 30 min.

[0088] The grinding aid in this example is prepared by stirring graphene, silica sol and deionized water in a weight ratio of 3:1:5.

[0089] The mass fraction of the sodium sulfite solution in this example is 20%.

[0090] Example 3.

[0091] A new process for deep chlorine removal from electric zinc solution in this example includes the following steps:

[0092] Step 1: Add 25 parts of bismuth oxide modifier to 50 parts of concentrated sulfuric acid to form a compounding agent.

[0093] Step 2: Then add 5 parts of modified nano-silica and continue to stir and mix thoroughly to obtain a modified solution.

[0094] Step 3: Add 15% of the modified solution in total amount to the solution to be treated, stir thoroughly, and then perform solid-liquid separation.

[0095] Step 4: Add 25% of the sodium sulfite solution in total amount to the solid-liquid separation product in Step 2 and treat for 1.5 h. That's all.

[0096] The preparation method of the bismuth oxide modifier in this example is as follows:

[0097] S01: Add bismuth oxide to 2.5 times the amount of sodium alginate solution with a mass fraction of 25%. Then add hydrochloric acid accounting for 7.5% of the total amount of bismuth oxide, and then add cetyltrimethoxysilane accounting for 3% of the total amount of bismuth oxide, stir and react thoroughly, and set aside.

[0098] S02: Add 15% of alkyl sulfonate and 3.5% of chitosan treatment agent to S01, continue to stir thoroughly, then wash with water and dry to obtain the bismuth oxide modifier.

[0099] The preparation method of the chitosan treatment agent in this example is as follows:

[0100] S101: Add 7.5 parts of chitosan to 12.5 parts of deionized water, and then add 3.5 parts of phosphate buffer solution and stir evenly.

[0101] S102: Then, add 3 parts of lanthanum sulfate to the product of S101, and continue to mix thoroughly to obtain the chitosan treatment agent.

[0102] In this embodiment, the rotation speed of the S01 stirring reaction is 750 r / min, and the stirring time is 25 min.

[0103] In this embodiment, the rotation speed of the S02 stirring is 1100 r / min, and the stirring time is 35 min.

[0104] In this embodiment, the pH value of the phosphate buffer solution is 5.5.

[0105] The preparation method of the modified nano-silica in this embodiment is as follows:

[0106] S11: Feed the nano-silica into 2.5 times the hydrochloric acid solution and stir to disperse it evenly, then add 2-hydroxyethylamine accounting for 7.5% of the total amount of the nano-silica, and continue to mix thoroughly;

[0107] S12: Finally, wash with water and dry, then add a grinding aid and grind in a grinder. After the grinding is completed, the modified nano-silica is obtained.

[0108] In this embodiment, the mass fraction of the hydrochloric acid solution is 12.5%; the rotation speed of the grinding treatment is 1250 r / min, and the grinding time is 25 min.

[0109] The grinding aid in this embodiment is prepared by stirring and mixing graphene, silica sol and deionized water in a weight ratio of 3:1:5.

[0110] In this embodiment, the mass fraction of the sodium sulfite solution is 15%.

[0111] Example 4.

[0112] A new process for deep chlorine removal from electric zinc solution in this embodiment includes the following steps:

[0113] Step 1: Add 22 parts of bismuth oxide modifier to 46 parts of concentrated sulfuric acid to form a compounding agent;

[0114] Step 2: Then add 3 - 7 parts of modified nano-silica and continue to stir and mix thoroughly to obtain a modified solution;

[0115] Step 3: Add 12% of the total amount of the modified solution to the liquid to be treated, stir thoroughly, and then perform solid-liquid separation;

[0116] Step 4: Add 22% of the total amount of the sodium sulfite solution to the solid-liquid separation product of Step 2 and treat for 1.2 h to complete.

[0117] The preparation method of the bismuth oxide modifier in this embodiment is:

[0118] S01: Add bismuth oxide into a sodium alginate solution with a mass fraction of 22% that is 2.2 times the amount of bismuth oxide. Subsequently, add it into hydrochloric acid that is 6% of the total amount of bismuth oxide. Then, add cetyltrimethoxysilane that is 2% of the total amount of bismuth oxide, and stir the reaction sufficiently for standby.

[0119] S02: Add 12% of alkyl sulfonate and 3% of chitosan treatment agent into S01, continue to stir sufficiently, then wash with water and dry to obtain a bismuth oxide modifier.

[0120] The preparation method of the chitosan treatment agent in this example is as follows:

[0121] S101: Add 6 parts of chitosan into 12 parts of deionized water, and then add 3 parts of phosphate buffer solution, and stir evenly.

[0122] S102: Then add 2 parts of lanthanum sulfate to the product of S101, and continue to mix sufficiently to obtain a chitosan treatment agent.

[0123] The stirring speed of S01 in this example is 600 r / min, and the stirring time is 22 min.

[0124] The stirring speed of S02 in this example is 1100 r / min, and the stirring time is 32 min.

[0125] The pH value of the phosphate buffer solution in this example is 5.5.

[0126] The preparation method of the modified nano-silica in this example is as follows:

[0127] S11: Feed nano-silica into a hydrochloric acid solution that is 2.2 times the amount of nano-silica and stir to disperse evenly. Subsequently, add 2-hydroxyethylamine that is 6% of the total amount of nano-silica, and continue to mix sufficiently.

[0128] S12: Finally, wash with water and dry, then add a grinding aid and grind in a grinding machine. After grinding, obtain modified nano-silica.

[0129] The mass fraction of the hydrochloric acid solution in this example is 12%; the rotation speed of the grinding treatment is 1210 r / min, and the grinding time is 22 min.

[0130] The grinding aid in this example is prepared by stirring graphene, silica sol, and deionized water in a weight ratio of 3:1:5.

[0131] The mass fraction of the sodium sulfite solution in this example is 12%.

[0132] Comparative Example 1.

[0133] Different from Example 3, the bismuth oxide modifier is replaced by bismuth oxide.

[0134] Comparative Example 2.

[0135] Different from Example 3, the chitosan treatment agent is not added to the bismuth oxide modifier.

[0136] Comparative Example 3.

[0137] Different from Example 3, modified nano-silica is not added.

[0138] Comparative Example 4.

[0139] Different from Example 3, the grinding aid is not added in the preparation of modified nano-silica.

[0140] Comparative Example 5.

[0141] Different from Example 3, modified nano-silica is replaced by nano-silica.

[0142] Perform performance tests on the products of Examples 1-4 and Comparative Examples 1-5;

[0143] Chlorine removal rate (%) Example 1 98.4 Example 2 98.6 Example 3 98.8 Example 4 98.5 Comparative Example 1 83.4 Comparative Example 2 87.6 Comparative Example 3 80.5 Comparative Example 4 87.3 Comparative Example 5 82.2

[0144] It can be seen from Comparative Examples 1-5 and Examples 1-4 that;

[0145] The product of Example 3 of the present invention has excellent chlorine removal performance; when the bismuth oxide modifier is replaced by bismuth oxide and modified nano-silica is not added, the chlorine removal performance of the product shows a deteriorating trend, while when the chitosan treatment agent is not added to the bismuth oxide modifier, the grinding aid is not added in the preparation of modified nano-silica, and modified nano-silica is replaced by nano-silica, the performance of the product deteriorates significantly. The modified nano-silica prepared by the method of the present invention improves the chlorine removal performance of the product most significantly, and the preparation effects by other methods are not as significant as that of the present invention.

[0146] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0147] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A process for deep chlorine removal from electric zinc solution, characterized in that It includes the following steps: Step 1: Add 20 - 30 parts of bismuth oxide modifier to 45 - 55 parts of concentrated sulfuric acid to form a compounding agent; Step 2: Subsequently, add 3 - 7 parts of modified nano - silica, and continue to stir and mix thoroughly to obtain a modified liquid; Step 3: Add 10 - 20% of the total amount of the modified liquid to the liquid to be treated, stir thoroughly, and then perform solid - liquid separation; Step 4: Add 20 - 30% of the total amount of sodium sulfite solution to the solid - liquid separation product in Step 2, and treat for 1 - 2 h to complete; The preparation method of the bismuth oxide modifier is as follows: S01: Add bismuth oxide to a sodium alginate solution with a mass fraction of 20 - 30% that is 2 - 3 times the amount, then add it to hydrochloric acid that is 5 - 10% of the total amount of bismuth oxide, and then add cetyltrimethoxysilane that is 1 - 5% of the total amount of bismuth oxide, stir and react thoroughly, and set aside; S02: Add 10 - 20% of alkyl sulfonate and 2 - 5% of chitosan treatment agent to S01, continue to stir thoroughly, then wash with water and dry to obtain the bismuth oxide modifier; The preparation method of the chitosan treatment agent is as follows: S101: Add 5 - 10 parts of chitosan to 10 - 15 parts of deionized water, then add 2 - 5 parts of phosphate buffer solution, and stir evenly; S102: Then add 1 - 5 parts of lanthanum sulfate to the product of S101, continue to mix thoroughly to obtain the chitosan treatment agent; The preparation method of the modified nano - silica is as follows: S11: Feed nano - silica into a hydrochloric acid solution that is 2 - 3 times the amount, stir and disperse evenly, then add 2 - hydroxyethylamine that is 5 - 10% of the total amount of nano - silica, and continue to mix thoroughly; S12: Finally, wash with water and dry, then add a grinding aid to a grinding machine for grinding treatment. After grinding, obtain the modified nano - silica.

2. The deep chlorine removal process for electric zinc solution according to claim 1, characterized in that, The stirring speed of the S01 reaction is 500 - 1000 r / min, and the stirring time is 20 - 30 min.

3. A process for deeply removing chlorine from electric zinc solution according to claim 1, characterized in that, The stirring speed of S02 is 1000 - 1200 r / min, and the stirring time is 30 - 40 min.

4. The deep chlorine removal process for electric zinc solution according to claim 1, wherein, The pH value of the phosphate buffer solution is 5.

5.

5. A process for deep chlorine removal from electric zinc solution according to claim 1, characterized in that, The mass fraction of the hydrochloric acid solution is 10 - 15%; the grinding speed is 1000 - 1500 r / min, and the grinding time is 20 - 30 min.

6. A process for deep chlorine removal from electric zinc solution according to claim 1, characterized in that, The grinding aid is prepared by stirring and mixing graphene, silica sol, and deionized water in a weight ratio of 3:1:

5.

7. A process for deep chlorine removal from electric zinc solution according to claim 1, characterized in that, The mass fraction of the sodium sulfite solution is 10 - 20%.