Method for treating zinc-containing residue

Abstract

The present application relates to a method for treating a zinc-containing residue. The treatment method comprises: performing alkali washing on a zinc-containing residue to obtain ammonia gas and an alkali washing slurry; performing solid-liquid separation on the alkali washing slurry to obtain a filter cake and a filtrate; sequentially performing washing and acid leaching on the filter cake to obtain a zinc sulfate solution and an aluminum residue; sequentially performing washing and alkali leaching on the aluminum residue to obtain an alkali leaching solution and an alkali-leached residue; performing electrolysis on the alkali leaching solution to obtain zinc and an aluminum-containing alkali solution; and performing aluminum removal treatment on the aluminum-containing alkali solution to obtain a composite defluorinating agent composed of aluminum oxide and calcium oxide and a regenerated alkali solution. The treatment method provided by the present application can realize the separation and resource recycling of aluminum, zinc, chlorine, and ammonia from a zinc-containing residue and the regeneration and recycling of an alkali solution, and the treatment process does not involve secondary waste, has low treatment energy consumption, and has economy and industrial feasibility.

Description

Treatment method of zinc-containing residue TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste treatment, in particular to a treatment method of zinc-containing residue. BACKGROUND

[0002] Zinc-containing residue is mainly derived from solid waste generated in the industrial processes of zinc smelting and processing, and its main components are ammonium chloride and aluminum, zinc hydroxide or oxide. As a secondary resource, if not utilized, it will pollute the surrounding environment. Therefore, the separation method and resource utilization approach of zinc-containing residue are the current research focus.

[0003] At present, the conventional separation methods mainly include pyrometallurgical method and hydrometallurgical method. The pyrometallurgical method usually directly volatilizes ammonium chloride to recover metals, but the equipment investment cost is high and the operation cost is high. The hydrometallurgical method usually separates ammonium chloride and aluminum-zinc by direct water washing by taking advantage of the fact that ammonium chloride is easily soluble in water, while aluminum-zinc hydroxide / oxide is insoluble. However, when the pH value of the solution is low, part of the zinc will dissolve, and when the pH value of the solution is high, a large amount of zinc-ammonium complex will be generated. Therefore, the ammonium chloride solution obtained will inevitably contain a large amount of zinc. At this time, if an additional metal removal agent is used to remove the zinc in the ammonium chloride solution, impurities will be introduced, and if ion exchange / extraction process is used, the operation will be complicated, which is not conducive to industrial production.

[0004] CN104862487A discloses a resource efficient conversion method of non-ferrous metal zinc smelting fly ash. The method uses ammonia-sulfamate solution to convert zinc in zinc ash into zinc-ammonium complex, and then uses ammonium bicarbonate to convert the zinc-ammonium complex into basic zinc carbonate product, realizing the resource utilization of zinc. However, the reagent consumption of this method is large, and the ammonia leaching mud is ash and has not been recycled, resulting in resource waste and high disposal cost.

[0005] CN109576500A discloses a process for recovering zinc, which includes zinc ash alkali washing to remove chlorine, leaching, goethite method to purify and remove impurities, copper salt to remove chlorine, three-stage purification, electrodeposition and smelting, etc. Although the leaching process can improve the recovery rate of zinc, it is not suitable for the treatment of zinc-containing residue, and does not disclose how to separate zinc and aluminum and realize resource utilization.

[0006] Therefore, it is a technical problem to be solved in the field to provide a treatment method suitable for the separation and resource utilization of zinc-containing residue. SUMMARY

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of protection of the claims.

[0008] In view of the above problems, the purpose of the present application is to provide a treatment method of zinc-containing residue, compared with the prior art, the treatment method provided by the present application can realize the separation and resource recovery of aluminum, zinc, chlorine and ammonia in the zinc-containing residue, can realize the regeneration and recycling of the lye, and the treatment process does not produce secondary waste, the treatment energy consumption is low, and it has economic efficiency and industrial feasibility.

[0009] In order to achieve the purpose of the present application, the following technical solutions are adopted in the present application:

[0010] The present application provides a treatment method of zinc-containing residue, which comprises the following steps:

[0011] (1) washing the zinc-containing residue with alkali to obtain ammonia gas and alkali washing slurry; performing solid-liquid separation on the alkali washing slurry to obtain filter mud and filtrate;

[0012] (2) sequentially washing and acid leaching the filter mud obtained in step (1) to obtain a zinc sulfate solution and aluminum mud;

[0013] (3) sequentially washing and alkali leaching the aluminum mud obtained in step (2) to obtain an alkali leaching solution and an alkali leaching mud;

[0014] (4) electrolyzing the alkali leaching solution obtained in step (3) to obtain zinc and an aluminum-containing lye; performing aluminum removal treatment on the aluminum-containing lye to obtain a composite defluorination agent composed of aluminum oxide and calcium oxide and a regenerated lye.

[0015] In the treatment method provided by the present application, the main components of the zinc-containing residue are ammonium chloride and aluminum-zinc hydroxide or oxide. First, alkali washing converts ammonium chloride in the zinc-containing residue into ammonia gas and sodium chloride, and also produces sodium aluminate and sodium zincate. Through alkali washing and solid-liquid separation, the separation of chlorinated salt and the removal of ammonia nitrogen are realized. Compared with the operation of sequentially performing liquid alkali treatment and water washing, the alkali washing in the present application can shorten the process flow, and the water content of the aluminum-zinc sludge after alkali washing is significantly reduced, which makes it easier to realize solid-liquid separation. Then, the filter mud is acid leached and the pH value of the acid leaching is controlled, so that only zinc is leached out and aluminum is not leached out, thereby obtaining pure zinc sulfate product and relatively pure aluminum mud, which can greatly reduce the content of zinc in the subsequent alkali leaching solution. Then, through alkali leaching and electrolysis, the sodium zincate in the alkali leaching solution is converted into zinc and sodium hydroxide, which can realize the removal of most of the zinc in the aluminum. The aluminum-containing lye obtained after electrolysis, which is a solution of sodium aluminate and sodium hydroxide, is subjected to the following chemical reaction with lime: 3Ca(OH)2+2NaAl(OH)4+aq=3CaO·Al2O3·6H2O+2NaOH+aq, which can realize the preparation of the composite defluorination agent and the regeneration of the lye.

[0016] In the present application, the solid-liquid ratio in alkali washing, acid leaching and alkali leaching can be adjusted as needed, and the solid-liquid ratio is generally controlled to be 1:5.

[0017] In one embodiment, the alkali used in the alkali washing of step (1) comprises sodium hydroxide.

[0018] In one embodiment, the amount of alkali used in the alkali washing exceeds the theoretical amount required for the reaction of alkali and ammonium chloride.

[0019] In one embodiment, the amount of alkali used in excess of the theoretical amount is 2-10% of the mass of the zinc-containing residue, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, but is not limited to the listed values, and other values not listed within the range of values are also applicable.

[0020] In this application, it is preferred to control the percentage of the mass of alkali used in excess of the theoretical amount to the mass of the zinc-containing residue, i.e. to ensure that the alkali satisfies one equivalent of ammonia nitrogen based on the complete reaction of alkali and ammonium chloride, and that the alkali washing slurry still maintains a suitable alkali environment after complete reaction, on the one hand to ensure the removal of zinc-ammonium complex so as to obtain pure sodium chloride subsequently, on the other hand the sludge is more easily filter-pressed under weak alkaline conditions, has a lower water content, and better achieves the separation of aluminum-zinc sludge and chlorinated salt, and on the other hand saves the cost of reagents.

[0021] In one embodiment, the zinc-containing residue contains 3-10% aluminum by mass percentage, for example, it can be 3%, 4%, 6%, 8% or 10%, 25-40% zinc, for example, it can be 25%, 26%, 28%, 30%, 32%, 34%, 36%, 38% or 40%, 15-35% ammonium chloride, for example, it can be 15%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34% or 35%, 5-20% water, for example, it can be 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%, but is not limited to the listed values, and other values not listed within the range of values are also applicable. The mass percentage of the above-mentioned aluminum and zinc refers to the content of aluminum or zinc elements, which actually exists as oxides or hydroxides in the zinc-containing residue, and the balance is a small amount of oxygen and hydroxide, as well as a small amount of sodium chloride.

[0022] In one embodiment, stirring is performed during the alkali washing of step (1).

[0023] In one embodiment, the stirring time during the alkali washing is 1-4h, for example, it can be 1h, 1.5h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.5h or 4h, but is not limited to the listed values, and other values not listed within the range of values are also applicable.

[0024] In one embodiment, the ammonia gas is subjected to absorption and evaporation crystallization in sequence in step (1) to obtain ammonium sulfate.

[0025] In the present application, the separated ammonia can be resourcefully utilized by absorption and evaporation crystallization to obtain ammonium sulfate product.

[0026] In one embodiment, the absorption agent used for absorption comprises sulfuric acid.

[0027] In one embodiment, the mass concentration of sulfuric acid used for absorption is 5-40%, for example, it can be 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38% or 40%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0028] In one embodiment, the content of aluminum in the filtrate in step (1) is 3000-8000 ppm, for example, it can be 3000 ppm, 4000 ppm, 5000 ppm, 6000 ppm, 7000 ppm or 8000 ppm, and the content of zinc is 200-1000 ppm, for example, it can be 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm or 1000 ppm, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0029] In one embodiment, the filtrate is subjected to pH adjustment and solid-liquid separation in sequence to obtain sodium chloride solution and precipitate.

[0030] In one embodiment, the adjusting agent used for pH adjustment comprises hydrochloric acid.

[0031] In one embodiment, the pH value of the slurry after pH adjustment is 8-10, for example, it can be 8, 8.2, 8.4, 8.6, 8.8, 9, 9.2, 9.4, 9.6, 9.8 or 10, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0032] In the present application, since the filtrate also contains a certain amount of aluminum and zinc, by adjusting the pH value and controlling the pH range, the aluminum and zinc can be precipitated exactly to obtain relatively pure sodium chloride solution, and then the separation and resourceful utilization of chlorine can be realized, and the purity of the obtained precipitate as an intermediate product does not affect the technical effects of the present application.

[0033] In one embodiment, the precipitate is washed with water to obtain first washing mud.

[0034] In one embodiment, the first washing mud returns to step (2) for acid leaching. In one embodiment, the first washing mud returns to step (2) for acid leaching.

[0035] In one embodiment, the washing liquid obtained after the washing of the precipitate is mixed with a sodium chloride solution.

[0036] In one embodiment, the sodium chloride solution is subjected to evaporation crystallization to obtain sodium chloride.

[0037] In one embodiment, the filter mud is washed with water to obtain a second washed mud.

[0038] In one embodiment, the washing liquid obtained after the washing of the filter mud is mixed with the filtrate.

[0039] In one embodiment, the acid leaching agent used in the acid leaching includes sulfuric acid.

[0040] In one embodiment, the pH value of the slurry in the acid leaching process is controlled to be 5.5-6.5, for example, it can be 5.5, 5.6, 5.7, 5.8, 5.9, 6, 6.1, 6.2, 6.3, 6.4 or 6.5, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0041] In the present application, by performing acid leaching and preferably controlling the pH value of the slurry in a specific range, zinc can be converted into zinc sulfate solution, and aluminum is not dissolved and still exists in the form of aluminum oxide or aluminum hydroxide in the sludge, thereby reducing the zinc content in the aluminum sludge and achieving the removal of most of the zinc in the aluminum.

[0042] In one embodiment, the temperature of the acid leaching is 75-95℃, for example, it can be 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 82℃, 84℃, 86℃, 88℃, 90℃, 92℃, 94℃ or 95℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0043] In the present application, the temperature in the acid leaching reaction process is preferably controlled in a specific range, which can dissolve 75-86% of the zinc in the sludge into zinc sulfate, lay a foundation for the subsequent resource recovery of zinc, and save the cost of reagents.

[0044] In one embodiment, the zinc sulfate solution is subjected to evaporation crystallization to obtain zinc sulfate.

[0045] In one embodiment, the aluminum sludge in step (3) is washed with water to obtain a third washed mud.

[0046] In one embodiment, the washing liquid obtained after the washing of the aluminum sludge is mixed with the zinc sulfate solution.

[0047] In one embodiment, the alkali leaching agent used in the alkali leaching in step (3) includes sodium hydroxide.

[0048] In one embodiment, the amount of alkali used in the alkali leaching exceeds the theoretical amount required to convert the aluminum-containing material into sodium aluminate.

[0049] In one embodiment, the amount of alkali used in excess of the theoretical amount is 2-10% of the mass of the aluminum sludge after washing, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0050] In the present application, it is preferred to control the percentage of the amount of alkali used in excess of the theoretical amount to the mass of the aluminum sludge after washing, i.e., based on the amount of alkali that is just enough to react with aluminum hydroxide / aluminum oxide to convert it into sodium aluminate, to ensure that the alkali meets the requirement of one equivalent for the reaction and that the slurry still maintains a suitable alkali environment after complete reaction, which enables the recovery of most of the aluminum while reducing the amount of reagents used and the cost.

[0051] In one embodiment, the temperature of the alkali leaching is 75-95°C, for example, it can be 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C or 95°C, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0052] In the present application, it is preferred to control the temperature of the alkali leaching within a specific range, which can control the conversion of 74-90% of the aluminum in the sludge into sodium aluminate, but at the same time, a small amount of zinc contained in the aluminum sludge is also converted into sodium zincate into the solution, which is subsequently removed by electrolysis.

[0053] In one embodiment, the alkali leached sludge is washed with water to obtain a fourth washed sludge.

[0054] In one embodiment, the washing liquid obtained after washing the alkali leached sludge is mixed with the alkali leaching liquid.

[0055] In one embodiment, the fourth washed sludge is returned to step (2) for acid leaching.

[0056] In the present application, the content of zinc in the fourth washed sludge increases after washing, and the content of aluminum significantly decreases, and the fourth washed sludge is returned to the acid leaching operation, which further realizes recycling.

[0057] In the present application, the zinc obtained by electrolysis is not sold as a product, but only used as an intermediate product for zinc sulfate production, so the parameters in the electrolysis process can use the conventional parameters for electrolytic zinc production, without the need for fine control.

[0058] In one embodiment, the voltage of the electrolysis in step (4) is 12-36 V, for example, it can be 12 V, 14 V, 16 V, 18 V, 20 V, 22 V, 24 V, 26 V, 28 V, 30 V, 32 V, 34 V or 36 V, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0059] In one embodiment, the current density of the electrolysis is 50-500 mA / cm 2 , for example, it can be 50 mA / cm 2 , 100 mA / cm 2 , 150 mA / cm 2 , 200 mA / cm 2 , 250 mA / cm 2 , 300 mA / cm 2 , 350 mA / cm 2 , 400 mA / cm 2 , 450 mA / cm 2 or 500 mA / cm 2 , but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0060] In one embodiment, the zinc obtained by the electrolysis is returned to step (2) for acid leaching.

[0061] In one embodiment, the aluminum removal agent used in the aluminum removal treatment comprises lime.

[0062] In one embodiment, the molar ratio of the lime to sodium aluminate in the aluminum-containing lye is (3-9):2, for example, it can be 3:2, 4:2, 5:2, 6:2, 7:2, 8:2 or 9:2, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0063] In the present application, by using lime to convert sodium aluminate into a composite fluoride removal agent of aluminum oxide and calcium oxide, the lye can be regenerated and recovered, the dosage and cost of the reagent can be reduced, the disposal cost can be reduced, and the economic efficiency and industrial feasibility of the process can be improved.

[0064] In one embodiment, the regenerated lye is used in the alkaline leaching in step (3).

[0065] As a preferred technical solution of the present application, the treatment method comprises the following steps:

[0066] (1) the zinc-containing residue is subjected to alkali washing, the alkali washing is stirred for 1-4 hours to obtain ammonia gas and alkali washing slurry, the amount of alkali used in the alkali washing exceeds the theoretical amount of alkali and ammonium chloride reaction, the excess amount of alkali accounts for 2-10% of the mass of the zinc-containing residue, the ammonia gas is absorbed by sulfuric acid and then evaporated and crystallized to obtain ammonium sulfate, the alkali washing slurry is subjected to pressure filtration to obtain filter mud and filtrate;

[0067] the content of aluminum in the filtrate is 3000-8000 ppm, the content of zinc is 200-1000 ppm, the filtrate is subjected to pH adjustment by hydrochloric acid to obtain a slurry with a pH value of 8-10, and then filtration is performed to obtain a sodium chloride solution and a precipitate, the precipitate is washed with water to obtain first washing mud, the first washing mud is returned to step (2) for acid leaching, the washing liquid obtained after washing of the precipitate is mixed with the sodium chloride solution, and the sodium chloride solution is subjected to evaporation and crystallization to obtain sodium chloride;

[0068] (2) the filter mud obtained in step (1) is washed with water to obtain second washing mud, the washing liquid obtained after washing of the filter mud is mixed with the filtrate, the second washing mud is subjected to acid leaching with sulfuric acid at a temperature of 75-95 DEG C, the pH value of the slurry is controlled to be 5.5-6.5 during the acid leaching, to obtain a zinc sulfate solution and aluminum mud, and the zinc sulfate solution is subjected to evaporation and crystallization to obtain zinc sulfate;

[0069] (3) the aluminum mud obtained in step (2) is washed with water to obtain third washing mud, the washing liquid obtained after washing of the aluminum mud is mixed with the zinc sulfate solution, the third washing mud is subjected to alkali leaching with sodium hydroxide at a temperature of 75-95 DEG C, the amount of alkali used in the alkali leaching exceeds the theoretical amount of alkali required for conversion of the aluminum-containing substance into sodium aluminate, the excess amount of alkali accounts for 2-10% of the mass of the washed aluminum mud, to obtain alkali leaching liquid and alkali leaching mud, the alkali leaching mud is washed with water to obtain fourth washing mud, the washing liquid obtained after washing of the alkali leaching mud is mixed with the alkali leaching liquid, and the fourth washing mud is returned to step (2) for acid leaching;

[0070] (4) the alkali leaching liquid obtained in step (3) is subjected to electrolysis to obtain zinc and an aluminum-containing alkali liquid, the zinc obtained by electrolysis is returned to step (2) for acid leaching, the aluminum-containing alkali liquid is subjected to aluminum removal treatment with lime, the molar ratio of the lime to sodium aluminate in the aluminum-containing alkali liquid is (3-9):2, to obtain a composite defluorination agent composed of aluminum oxide and calcium oxide and a regenerated alkali liquid, and the regenerated alkali liquid is used in the alkali leaching in step (3).

[0071] Compared with the prior art, the present application has the following beneficial effects:

[0072] (1) The treatment method provided in the application can realize the separation and recovery of aluminum, zinc, chlorine and ammonia in the zinc-containing residue, obtain resource products such as aluminum oxide / calcium oxide composite defluorination agent, zinc sulfate, sodium chloride and ammonium sulfate, and can also realize the regeneration and reuse of lye, and the treatment process does not produce additional secondary waste, has low energy consumption, and has economic efficiency and industrial feasibility.

[0073] (2) The treatment method provided in the application can realize the removal of ammonia nitrogen by preliminary treatment of the zinc-containing residue by alkali washing, and the water content of the sludge is lower after alkali washing, which can better realize the separation of aluminum-zinc sludge and chlorinated salt.

[0074] (3) The treatment method provided in the application can obtain pure zinc sulfate product and relatively pure aluminum sludge by selective leaching of zinc by acid leaching and leaching of aluminum by alkali leaching, and convert sodium zincate into zinc and sodium hydroxide by electrolysis, thereby realizing the effect of removing zinc from aluminum. Compared with the process of realizing aluminum-zinc removal by pyrometallurgy, the energy consumption and operating cost are reduced, and the implementation is simpler.

[0075] (4) The treatment method provided in the application can realize the recycling of alkali by treating the aluminum-containing lye with lime to obtain regenerated lye, reduce the treatment cost, and is conducive to industrial application.

[0076] Other aspects can be appreciated upon reading and understanding the attached figures and detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0077] The accompanying drawings are included to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0078] FIG. 1 is a flowchart of the treatment method according to the embodiment 1 of the present application. DETAILED DESCRIPTION

[0079] The technical solutions of the present application will be further described by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0080] Embodiment 1

[0081] The embodiment provides a treatment method of zinc-containing residue, the zinc-containing residue contains 9% of aluminum, 25% of zinc and 25% of ammonium chloride by mass percentage, as shown in FIG. 1, the treatment method comprises the following steps:

[0082] (1) the zinc-containing residue is subjected to alkali washing with sodium hydroxide solution, the alkali washing is stirred for 3 hours, ammonia gas and alkali washing slurry are obtained, the amount of alkali used in the alkali washing exceeds the theoretical amount of alkali required for the reaction of alkali and ammonium chloride, the mass of the alkali exceeding the theoretical amount accounts for 10% of the mass of the zinc-containing residue, the ammonia gas is absorbed with 10% sulfuric acid, then evaporated and crystallized to obtain ammonium sulfate, the alkali washing slurry is subjected to pressure filtration to obtain filter mud and filtrate;

[0083] the filtrate is subjected to pH adjustment with hydrochloric acid to obtain a slurry with a pH value of 9.0, then filtered to obtain a sodium chloride solution and a precipitate, the precipitate is washed with water to obtain first washing mud, the first washing mud is returned to step (2) for acid leaching, the washing liquid obtained after washing of the precipitate is mixed with the sodium chloride solution, and the sodium chloride solution is subjected to evaporative crystallization to obtain sodium chloride;

[0084] (2) the filter mud obtained in step (1) is washed with water to obtain second washing mud, the washing liquid obtained after washing of the filter mud is mixed with the filtrate, and the second washing mud is subjected to acid leaching with sulfuric acid at a temperature of 75°C, the pH value of the slurry is controlled to be 6.5 during the acid leaching to obtain a zinc sulfate solution and aluminum mud, and the zinc sulfate solution is subjected to evaporative crystallization to obtain zinc sulfate;

[0085] (3) the aluminum mud obtained in step (2) is washed with water to obtain third washing mud, the washing liquid obtained after washing of the aluminum mud is mixed with the zinc sulfate solution, and the third washing mud is subjected to alkali leaching with sodium hydroxide at a temperature of 75°C, the amount of alkali used in the alkali leaching exceeds the theoretical amount required for the conversion of aluminum-containing substances into sodium aluminate, the mass of the alkali exceeding the theoretical amount accounts for 10% of the mass of the washed aluminum mud, to obtain alkali leaching liquid and alkali leaching mud, the alkali leaching mud is washed with water to obtain fourth washing mud, the washing liquid obtained after washing of the alkali leaching mud is mixed with the alkali leaching liquid, and the fourth washing mud is returned to step (2) for acid leaching;

[0086] (4) the alkali leaching liquid obtained in step (3) is subjected to electrolysis under the conditions of an electric voltage of 30V and an electric current density of 480mA / cm 2 to obtain zinc and an aluminum-containing alkali liquid, the zinc obtained by electrolysis is returned to step (2) for acid leaching, the aluminum-containing alkali liquid is subjected to aluminum removal treatment with lime, the molar ratio of the lime to sodium aluminate in the aluminum-containing alkali liquid is 4:2, to obtain a composite defluorination agent composed of aluminum oxide and calcium oxide and a regenerated alkali liquid, and the regenerated alkali liquid is reused in the alkali leaching in step (3).

[0087] Example 2

[0088] The present embodiment provides a treatment method for zinc-containing residue, the zinc-containing residue contains 6% aluminum, 18% zinc and 30% ammonium chloride in terms of mass percentage, and the treatment method comprises the following steps:

[0089] (1) the zinc-containing residue is subjected to alkali washing with a sodium hydroxide solution, the alkali washing is stirred for 2.5 hours, ammonia gas and alkali washing slurry are obtained, the amount of alkali used in the alkali washing exceeds the theoretical amount of alkali and ammonium chloride reaction, the mass of the alkali exceeding the theoretical amount accounts for 2% of the mass of the zinc-containing residue, the ammonia gas is absorbed with 10% sulfuric acid, then evaporated and crystallized to obtain ammonium sulfate, the alkali washing slurry is subjected to pressure filtration to obtain filter mud and filtrate;

[0090] the filtrate is subjected to pH value adjustment with hydrochloric acid to obtain a slurry with a pH value of 9.5, then filtered to obtain a sodium chloride solution and a precipitate, the precipitate is washed with water to obtain first washing mud, the first washing mud is returned to step (2) for acid leaching, the washing liquid obtained after washing of the precipitate is mixed with the sodium chloride solution, and the sodium chloride solution is subjected to evaporative crystallization to obtain sodium chloride;

[0091] (2) the filter mud obtained in step (1) is washed with water to obtain second washing mud, the washing liquid obtained after washing of the filter mud is mixed with the filtrate, the second washing mud is subjected to acid leaching with sulfuric acid at a temperature of 95°C, the pH value of the slurry is controlled to be 5.5 during the acid leaching, zinc sulfate solution and aluminum mud are obtained, and the zinc sulfate solution is subjected to evaporative crystallization to obtain zinc sulfate;

[0092] (3) the aluminum mud obtained in step (2) is washed with water to obtain third washing mud, the washing liquid obtained after washing of the aluminum mud is mixed with the zinc sulfate solution, the third washing mud is subjected to alkali leaching with sodium hydroxide at a temperature of 95°C, the amount of alkali used in the alkali leaching exceeds the theoretical amount of conversion of aluminum-containing substances into sodium aluminate, the mass of the alkali exceeding the theoretical amount accounts for 2% of the mass of the washed aluminum mud, alkali leaching liquid and alkali leaching mud are obtained, the alkali leaching mud is washed with water to obtain fourth washing mud, the washing liquid obtained after washing of the alkali leaching mud is mixed with the alkali leaching liquid, and the fourth washing mud is returned to step (2) for acid leaching;

[0093] (4) the alkali leaching liquid obtained in step (3) is subjected to electrolysis under the conditions of an electric voltage of 30V and a current density of 480mA / cm 2 , zinc and an aluminum-containing alkali liquid are obtained, the zinc obtained by electrolysis is returned to step (2) for acid leaching, the aluminum-containing alkali liquid is subjected to aluminum removal treatment with lime, the molar ratio of the lime to sodium aluminate in the aluminum-containing alkali liquid is 6:2, a composite defluorination agent composed of aluminum oxide and calcium oxide and regenerated alkali liquid are obtained, and the regenerated alkali liquid is used in the alkali leaching in step (3).

[0094] Example 3

[0095] The embodiment provides a treatment method of zinc-containing residue, the zinc-containing residue contains 3% of aluminum, 35% of zinc and 20% of ammonium chloride in percentage by mass, and the treatment method comprises the following steps:

[0096] (1) the zinc-containing residue is subjected to alkali washing by using a sodium hydroxide solution, stirring is carrieduted during the alkali washing for 2 hours, ammonia gas and alkali washing slurry are obtained, the alkali consumption in the alkali washing exceeds the theoretical consumption of the reaction between alkali and ammonium chloride, the mass of the alkali exceeding the theoretical consumption accounts for 6% of the mass of the zinc-containing residue, the ammonia gas is absorbed by using 10% sulfuric acid, then evaporation crystallization is carried out to obtain ammonium sulfate, the alkali washing slurry is subjected to pressure filtration to obtain filter mud and filtrate;

[0097] the filtrate is subjected to pH value adjustment by using hydrochloric acid to obtain a slurry with a pH value of 8.5, then filtration is carried out to obtain a sodium chloride solution and a precipitate, the precipitate is washed by using water to obtain first washing mud, the first washing mud returns to step (2) for acid leaching, the washing liquid obtained after washing of the precipitate is mixed with the sodium chloride solution, and the sodium chloride solution is subjected to evaporation crystallization to obtain sodium chloride;

[0098] (2) the filter mud obtained in step (1) is washed by using water to obtain second washing mud, the washing liquid obtained after washing of the filter mud is mixed with the filtrate, the second washing mud is subjected to acid leaching by using sulfuric acid under the condition that the temperature is 85 DEG C, the pH value of the slurry is controlled to be 6 during the acid leaching, zinc sulfate solution and aluminum mud are obtained, and the zinc sulfate solution is subjected to evaporation crystallization to obtain zinc sulfate;

[0099] (3) the aluminum mud obtained in step (2) is washed by using water to obtain third washing mud, the washing liquid obtained after washing of the aluminum mud is mixed with the zinc sulfate solution, the third washing mud is subjected to alkali leaching by using sodium hydroxide under the condition that the temperature is 85 DEG C, the alkali consumption in the alkali leaching exceeds the theoretical consumption of the conversion of aluminum-containing substances into sodium aluminate, the mass of the alkali exceeding the theoretical consumption accounts for 6% of the mass of the aluminum mud after washing, alkali leaching liquid and alkali leaching mud are obtained, the alkali leaching mud is washed by using water to obtain fourth washing mud, the washing liquid obtained after washing of the alkali leaching mud is mixed with the alkali leaching liquid, and the fourth washing mud returns to step (2) for acid leaching;

[0100] (4) the alkali leaching liquid obtained in step (3) is subjected to electrolysis under the condition that the voltage is 30V and the current density is 480mA / cm 2 , zinc and aluminum-containing alkali liquid are obtained, the zinc obtained by electrolysis returns to step (2) for acid leaching, the aluminum-containing alkali liquid is subjected to aluminum removal treatment by using lime, the molar ratio of the lime to sodium aluminate in the aluminum-containing alkali liquid is 8:2, a composite defluorination agent composed of aluminum oxide and calcium oxide and regenerated alkali liquid are obtained, and the regenerated alkali liquid is used in the alkali leaching in step (3).

[0101] Embodiment 4

[0102] The present embodiment provides a treatment method for zinc-containing residue, which is different from that of Embodiment 1 only in that the mass of the excess alkali over the theoretical amount accounts for 0.5% of the mass of the zinc-containing residue.

[0103] Embodiment 5

[0104] The present embodiment provides a treatment method for zinc-containing residue, which is different from that of Embodiment 1 only in that the mass of the excess alkali over the theoretical amount accounts for 15% of the mass of the zinc-containing residue.

[0105] Embodiment 6

[0106] The present embodiment provides a treatment method for zinc-containing residue, which is different from that of Embodiment 1 only in that the pH value of the slurry is controlled to be 4 during the acid leaching.

[0107] Embodiment 7

[0108] The present embodiment provides a treatment method for zinc-containing residue, which is different from that of Embodiment 1 only in that the mass of the excess alkali over the theoretical amount accounts for 0.5% of the mass of the aluminum mud after washing.

[0109] Embodiment 8

[0110] The present embodiment provides a treatment method for zinc-containing residue, which is different from that of Embodiment 1 only in that the mass of the excess alkali over the theoretical amount accounts for 15% of the mass of the aluminum mud after washing.

[0111] The components of the filtrate in Embodiments 1-8 were detected, and the results are shown in Table 1; the components and purity of the sodium chloride solution were detected, and the results are shown in Table 2; the components, purity and zinc recovery rate of the zinc sulfate solution were detected, and the results are shown in Table 3; the components, aluminum leaching rate of the alkali leaching solution were detected, and the results are shown in Table 4; the components, aluminum purity of the aluminum-containing alkali solution were detected, and the results are shown in Table 5; the aluminum concentration, aluminum recovery rate and alkali recovery rate of the regenerated alkali solution were detected, and the results are shown in Table 6.

[0112] Table 1

[0113] In Table 1, “-” indicates that the data at this place is consistent with the corresponding data in Embodiment 1.

[0114] Table 2

[0115] In Table 2, “-” indicates that the data at this place is consistent with the corresponding data in Embodiment 1.

[0116] From the data in Table 1 and Table 2, it can be seen that the content of ammonia nitrogen in the filtrate can be reduced to below 896 ppm, and under more optimal conditions, can be reduced to below 43 ppm; the purity of the sodium chloride solution reaches above 95.27%, and under more optimal conditions, reaches above 99.83%. Compared with Example 1, the percentage of excess alkali in the alkali washing in Examples 4-5 is not within the preferred range of the present application, the content of ammonia nitrogen in Example 1 is significantly lower than that in Example 4, and the purity of the sodium chloride solution is significantly higher than that in Example 4, and the cost of alkali in Example 1 is significantly lower than that in Example 5. Therefore, the present application preferably controls the percentage of the mass of excess alkali over the mass of the zinc-containing residue, which can effectively separate and recover ammonia and chlorine, and reduce the processing cost.

[0117] Table 3

[0118] In Table 3, “-” indicates that the data at this place is consistent with the corresponding data in Example 1.

[0119] In Table 3, “zinc recovery rate” refers to the percentage of zinc transferred into the zinc sulfate solution over the zinc contained in the filter mud.

[0120] From Table 3, it can be seen that the present application can leach zinc sulfate through the step of acid leaching, so that the purity of the zinc sulfate solution reaches above 99.53%, and under more optimal conditions, reaches above 99.91%, and the zinc recovery rate reaches above 76.57%. Through the comparison between Example 1 and Example 6, it can be seen that the present application can further improve the purity of the zinc sulfate solution by preferably controlling the pH value of the slurry during the acid leaching process, and obtain a zinc sulfate product with higher purity.

[0121] Table 4

[0122] In Table 4, “-” indicates that the data at this place is consistent with the corresponding data in Example 1.

[0123] In Table 4, “aluminum leaching rate” refers to the percentage of aluminum transferred into sodium aluminate over the aluminum contained in the aluminum mud.

[0124] From the data in Table 4, it can be seen that the present application can achieve an aluminum leaching rate of above 74.05% through alkali leaching, and under more optimal conditions, can achieve above 76.86%. Through the comparison between Example 1 and Examples 7-8, it can be seen that the addition amount of alkali in Example 7 is too small, which leads to a decrease in the aluminum leaching rate, and in Example 8, the cost of alkali is too high and a large amount of zinc is introduced, which increases the cost of subsequent electrolysis. Therefore, the present application preferably controls the percentage of the mass of excess alkali over the mass of the cleaned aluminum mud, which can ensure a certain aluminum leaching rate while reducing the production cost.

[0125] Table 5

[0126] In Table 5, "-" means that the data at this place is consistent with the corresponding data in Example 1.

[0127] From the data in Table 5, it can be seen that the purity of aluminum in the aluminum-containing alkaline solution can reach more than 99.93% by electrolysis. As mentioned before, the recovery rate of aluminum in Example 7 is lower, and the content of zinc in Example 8 is too high, although the purity of aluminum can still be maintained, the electrolysis cost is too high. Therefore, by preferably controlling the percentage of the mass of the alkali exceeding the theoretical amount to the mass of the aluminum mud after cleaning, the application can ensure a certain recovery rate of aluminum while ensuring a high purity of aluminum and reducing production costs.

[0128] Table 6

[0129] In Table 6, "-" means that the data at this place is consistent with the corresponding data in Example 1.

[0130] In Table 6, "the recovery rate of aluminum" refers to the percentage of aluminum in the composite fluoride removal agent to the aluminum contained in the aluminum-containing alkaline solution.

[0131] In Table 6, "the recovery rate of alkali" refers to the percentage of the recovered alkali to the alkali used for alkali leaching.

[0132] From the data in Table 6, it can be seen that the application can recover aluminum and alkali separately by lime aluminum removal treatment, so that the recovery rate of aluminum can reach more than 87.57%, and under the more optimal conditions, it can reach more than 87.68%; the recovery rate of alkali can reach more than 77.68%.

[0133] In summary, the treatment method provided by the application can separate and recycle aluminum, zinc, chlorine and ammonia in the zinc-containing residue, can regenerate and reuse the alkaline solution, and the treatment process does not produce secondary waste, the treatment energy consumption is low, and it has economic and industrial feasibility.

[0134] The applicant declares that the above is only a specific embodiment of the application, but the protection scope of the application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the application.

Claims

1. A method for treating zinc-containing residue, comprising the following steps: (1) washing the zinc-containing residue with alkali to obtain ammonia gas and alkali washing slurry, and performing solid-liquid separation on the alkali washing slurry to obtain filter mud and filtrate; (2) sequentially washing and acid leaching the filter mud obtained in step (1) to obtain zinc sulfate solution and aluminum mud; (3) sequentially washing and alkali leaching the aluminum mud obtained in step (2) to obtain alkali leaching solution and alkali leaching mud; (4) performing electrolysis on the alkali leaching solution obtained in step (3) to obtain zinc and aluminum-containing alkali liquor, and performing aluminum removal treatment on the aluminum-containing alkali liquor to obtain composite fluoride removal agent composed of aluminum oxide and calcium oxide and regenerated alkali liquor.

2. The treatment method of claim 1, wherein, The alkali used in the alkali washing of step (1) comprises sodium hydroxide; Optionally, the amount of alkali used in the alkali washing exceeds the theoretical amount required for the reaction of alkali and ammonium chloride; Optionally, the mass of the alkali exceeding the theoretical amount accounts for 2-10% of the mass of the zinc-containing residue; Optionally, the zinc-containing residue contains 3-10% of aluminum, 25-40% of zinc, 15-35% of ammonium chloride and 5-20% of water in terms of mass percentage.

3. The treatment method according to claim 1 or 2, wherein, Stirring is performed during the alkali washing of step (1); Optionally, the stirring time during the alkali washing is 1-4 h.

4. The treatment method according to any one of claims 1 to 3, wherein, The ammonia gas obtained in step (1) is sequentially absorbed and evaporated to obtain ammonium sulfate; Optionally, the absorbent used in the absorption comprises sulfuric acid.

5. The treatment method according to any one of claims 1-4, wherein, The content of aluminum in the filtrate obtained in step (1) is 3000-8000 ppm, and the content of zinc is 200-1000 ppm; Optionally, the filtrate is sequentially subjected to pH adjustment and solid-liquid separation to obtain sodium chloride solution and precipitate; Optionally, the adjusting agent used in the pH adjustment comprises hydrochloric acid; Optionally, the pH value of the slurry after the pH adjustment is 8-10; Optionally, the precipitate is washed with water to obtain first washing mud; Optionally, the first washing mud is returned to step (2) for acid leaching; Optionally, the washing liquid obtained after the washing of the precipitate is mixed with the sodium chloride solution; Optionally, the sodium chloride solution is evaporated to obtain sodium chloride.

6. The treatment method according to any one of claims 1-5, wherein, The filter mud obtained in step (2) is washed with water to obtain second washing mud; Optionally, the washing liquid obtained after the washing of the filter mud is mixed with the filtrate; Optionally, the acid leaching agent used in the acid leaching comprises sulfuric acid; Optionally, the pH value of the slurry is controlled to be 5.5-6.5 during the acid leaching; Optionally, the temperature of the acid leaching is 75-95°C; Optionally, the zinc sulfate solution is evaporated to obtain zinc sulfate.

7. The treatment method according to any one of claims 1-6, wherein, The aluminum mud obtained in step (3) is washed with water to obtain third washing mud; Optionally, the washing liquid obtained after the washing of the aluminum mud is mixed with the zinc sulfate solution.

8. The treatment method according to any one of claims 1-7, wherein, The alkali leaching agent used in the alkali leaching of step (3) comprises sodium hydroxide; Optionally, the amount of alkali used in the alkali leaching exceeds the theoretical amount required for the conversion of aluminum-containing substances into sodium aluminate; Optionally, the mass of the alkali exceeding the theoretical amount accounts for 2-10% of the mass of the washed aluminum mud; Optionally, the temperature of the alkali leaching is 75-95°C; Optionally, the alkali leaching mud is washed with water to obtain fourth washing mud; Optionally, the washing liquid obtained after the washing of the alkali leaching mud is mixed with the alkali leaching solution; Optionally, the fourth washing mud returns to step (2) for acid leaching.

9. The treatment method according to any one of claims 1-8, wherein, The zinc obtained from the electrolysis of step (4) returns to step (2) for acid leaching; Optionally, the aluminum removal agent used in the aluminum removal treatment comprises lime; Optionally, the molar ratio of lime to sodium aluminate in the aluminum-containing lye is (3-9):2; Optionally, the regenerated lye is used in the alkali leaching of step (3).

10. The treatment method according to any one of claims 1-9, wherein, The treatment method comprises the following steps: (1) alkali washing of the zinc-containing residue, wherein the alkali washing is stirred for 1-4 hours, ammonia gas and alkali washing slurry are obtained, the amount of alkali used in the alkali washing exceeds the theoretical amount of alkali required for the reaction of alkali and ammonium chloride, the excess amount of alkali accounts for 2-10% of the mass of the zinc-containing residue, the ammonia gas is absorbed by sulfuric acid, then evaporated and crystallized to obtain ammonium sulfate, the alkali washing slurry is subjected to pressure filtration to obtain filter mud and filtrate; The content of aluminum in the filtrate is 3000-8000 ppm, and the content of zinc is 200-1000 ppm, the filtrate is adjusted to a pH value of 8-10 by hydrochloric acid, then filtered to obtain a sodium chloride solution and a precipitate, the precipitate is washed with water to obtain first washing mud, the first washing mud returns to step (2) for acid leaching, the washing liquid obtained after washing of the precipitate is mixed with the sodium chloride solution, and the sodium chloride solution is evaporated and crystallized to obtain sodium chloride; (2) the filter mud obtained in step (1) is washed with water to obtain second washing mud, the washing liquid obtained after washing of the filter mud is mixed with the filtrate, the second washing mud is subjected to acid leaching with sulfuric acid at a temperature of 75-95℃, the pH value of the slurry is controlled to be 5.5-6.5 during the acid leaching, zinc sulfate solution and aluminum mud are obtained, and the zinc sulfate solution is evaporated and crystallized to obtain zinc sulfate; (3) the aluminum mud obtained in step (2) is washed with water to obtain third washing mud, the washing liquid obtained after washing of the aluminum mud is mixed with the zinc sulfate solution, the third washing mud is subjected to alkali leaching with sodium hydroxide at a temperature of 75-95℃, the amount of alkali used in the alkali leaching exceeds the theoretical amount of alkali required for the conversion of aluminum-containing substances into sodium aluminate, the excess amount of alkali accounts for 2-10% of the mass of the washed aluminum mud, alkali leaching liquid and alkali leaching mud are obtained, the alkali leaching mud is washed with water to obtain fourth washing mud, the washing liquid obtained after washing of the alkali leaching mud is mixed with the alkali leaching liquid, and the fourth washing mud returns to step (2) for acid leaching; (4) the alkali leaching liquid obtained in step (3) is subjected to electrolysis to obtain zinc and aluminum-containing lye, the zinc obtained from the electrolysis returns to step (2) for acid leaching, the aluminum-containing lye is subjected to aluminum removal treatment with lime, the molar ratio of lime to sodium aluminate in the aluminum-containing lye is (3-9):2, composite fluoride removal agent composed of aluminum oxide and calcium oxide and regenerated lye are obtained, and the regenerated lye is used in the alkali leaching of step (3).

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