Resourceful treatment method of sulfuric acid-containing waste liquid

Abstract

The invention belongs to the technical field of resource utilization, and discloses a resource treatment method for waste liquid containing sulfuric acid. The treatment method comprises the following steps: respectively feeding the sulfuric acid-containing waste liquid and water into a membrane-method acid recovery system in a convection manner, and carrying out acid recovery to obtain a deacidified lithium slag desulfurized liquid and recovered acid; sequentially carrying out alkalization polymerization, evaporative crystallization, filtration and drying on the deacidified lithium slag desulfurization liquid to obtain the composite flocculant. And evaporating and concentrating the recovered acid. The membrane method acid recovery system is introduced to replace the process of neutralizing and removing impurity cations by using quicklime, sodium carbonate and the like in the traditional technology, the problem of lithium slag treatment is solved, meanwhile, efficient recovery and cyclic utilization of an acid solution and metal ions are also realized, the treatment cost and environmental influence are reduced, and the method is suitable for industrial production. Good application prospects and market potential are shown, and powerful support is provided for sustainable development of the new energy industry.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource utilization, and particularly relates to a resource treatment method of sulfuric acid-containing waste liquid. BACKGROUND

[0002] Under the background of rapid development of new energy industry, especially the rapid expansion of lithium ion battery manufacturing field, the treatment and resource utilization of lithium residue as a byproduct have gradually become prominent. Lithium residue contains various valuable metal elements, but it is difficult to utilize directly. Therefore, acidolysis treatment of lithium residue has become a common resource utilization method.

[0003] The acidolysis process of lithium residue is a key link, and the acid solution (i.e. lithium residue desulfurization liquid) produced in this process contains high-concentration sulfuric acid and various valuable metal ions. The traditional treatment method tends to use alkaline substances to directly neutralize such acid solution, but this not only consumes a large amount of alkaline resources, but also the further utilization value of the neutralization product (such as sulfate precipitate) is limited, which undoubtedly limits the effective recovery and recycling of resources.

[0004] Therefore, it is particularly important to explore an efficient and environmentally friendly treatment scheme for lithium residue desulfurization liquid (i.e. acid solution rich in metal ions formed after acidolysis). SUMMARY

[0005] The present application aims to provide a resource treatment method of sulfuric acid-containing waste liquid, which solves the problem of consumption of existing resources and difficulty in effective recovery and utilization of waste liquid resources in the prior art when treating acid waste liquid (such as acidolysis liquid of lithium residue).

[0006] In order to achieve the above-mentioned application purpose, the present application provides the following technical scheme: The present application provides a resource treatment method of sulfuric acid-containing waste liquid, comprising the following steps: (1) The sulfuric acid-containing waste liquid and water are respectively sent into a membrane acid recovery system in a countercurrent manner to recover acid, to obtain desulfurized lithium residue desulfurization liquid and recovered acid; (2) The desulfurized lithium residue desulfurization liquid is sequentially subjected to alkalization polymerization, evaporation crystallization, filtration and drying to obtain a composite flocculant; (3) The recovered acid is subjected to evaporation concentration; Wherein, step (2) and step (3) have no sequence.

[0007] Further, in the method, the sulfuric acid-containing waste liquid in step (1) includes one or more of lithium residue acid leaching desulfurization liquid, metal pickling sulfuric acid-containing waste liquid, petroleum refining desulfurization sulfuric acid-containing waste liquid, and dye synthesis sulfuric acid-containing waste liquid; The cations in the sulfuric acid-containing waste liquid in step (1) include H +one or more of Li + , Na + , Al 3+ , Fe 2+ , Fe 3+ , Ca 2+ , Mg 2+ , and SO4 2- .

[0008] Further, in the method, the convection mode of step (1) is that the sulfuric acid-containing waste liquid and water flow into and out of the membrane acid recovery system in opposite directions.

[0009] Further, in the method, the membrane acid recovery system of step (1) includes a reaction membrane stack, a peristaltic pump, and connecting pipe fittings, and the reaction membrane stack includes one or more of a diffusion dialysis membrane unit, a nanofiltration membrane unit, and an electrodialysis membrane unit.

[0010] Further, in the method, the diffusion dialysis membrane unit includes a plate-and-frame diffusion dialysis membrane unit, a roll-type diffusion dialysis membrane unit, or a hollow fiber diffusion dialysis membrane unit.

[0011] Further, in the method, the membrane acid recovery system of step (1) includes an acid inlet, a water inlet, an acid outlet, and a water outlet, the acid inlet is used to send in the lithium residue desulfurization liquid, the water inlet is used to send in water, the acid outlet is used to obtain the desulfurized lithium residue desulfurization liquid, and the water outlet is used to obtain the recovered acid.

[0012] Further, in the method, the liquid temperature in the membrane acid recovery system of step (1) is 25-60°C.

[0013] Further, in the method, the flow rate of the sulfuric acid-containing waste liquid sent into the membrane acid recovery system of step (1) is 0.6-3.6 L / h, and the flow rate of the water is 0.8-1.5 times that of the sulfuric acid-containing waste liquid.

[0014] Further, in the method, the evaporation concentration temperature of step (3) is 70-120°C.

[0015] According to the above technical solution, compared with the prior art, the present application has the following beneficial effects: The application provides a sulfuric acid-containing waste liquid treatment scheme based on a membrane separation technology. As an advanced feed liquid treatment and separation technology, the membrane separation technology is characterized in that a semi-permeable membrane or a specific ion exchange membrane with selective permeability is used to realize efficient migration of solutes in a solution. The scheme of the application not only realizes recycling of acid in a front-end process (such as lithium residue acidolysis), but also significantly reduces consumption of alkaline substances required in preparation of a flocculant in a rear-end process. Specifically, through selective permeability of the membrane, hydrogen ions in the lithium residue desulfurization solution are efficiently migrated to a receiving solution, while other impurities and metal ions in the solution are effectively intercepted, so that high-purity acid recovery is realized. The recovered acid can be directly recycled (such as recycled for lithium residue acidolysis), forming a closed recycling system, and greatly improving resource utilization efficiency. In addition, since the membrane separation technology effectively reduces the alkali consumption in the preparation of the flocculant in the rear-end process, the wastewater treatment cost is significantly reduced, and the environmental burden caused by the use of alkaline substances is also reduced, embodying the concept of energy saving and environmental protection.

[0016] Therefore, the application introduces a membrane acid recovery system to replace the process of removing impurity cations by using quicklime and soda ash in the traditional technology, not only realizes recycling of acid in the front-end process, but also greatly reduces the alkali consumption in the preparation of the flocculant in the rear-end process, saves energy and protects the environment, and reduces the cost. In the recovery process of the acid recovery process, the total acid recovery rate is ≥80%, and the metal salt interception rate is ≥90%. While solving the problems in the lithium residue treatment process, the application also realizes efficient recovery and recycling of acid solution and metal ions, reduces the treatment cost and environmental impact, and has good application prospect and market potential, providing strong support for sustainable development of the new energy industry. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description.

[0018] Figure 1 A resource treatment method flowchart for lithium residue acid leaching desulfurization solution; Figure 2 A schematic diagram of a plate-and-frame diffusion dialysis unit. DETAILED DESCRIPTION

[0019] The application provides a resource treatment method for sulfuric acid-containing waste liquid, comprising the following steps: (1) The sulfuric acid-containing waste liquid and water are respectively sent into a membrane acid recovery system in a countercurrent manner to recover acid, and obtain a lithium residue desulfurization solution after acid removal and recovered acid; (2) The lithium residue desulfurization solution after acid removal is sequentially subjected to alkalization polymerization, evaporation crystallization, filtration and drying to obtain a composite flocculant; (3) The recovered acid is subjected to evaporation concentration; There is no specific order between steps (2) and (3).

[0020] In this invention, the sulfuric acid waste liquid in step (1) preferably includes one or more of the following: lithium slag acid leaching desulfurization liquid, metal pickling sulfuric acid waste liquid, petroleum refining desulfurization sulfuric acid waste liquid, and dye synthesis sulfuric acid waste liquid. More preferably, it includes lithium slag acid leaching desulfurization liquid and / or metal pickling sulfuric acid waste liquid. More preferably, it is lithium slag acid leaching desulfurization liquid.

[0021] In this invention, the lithium slag acid leaching desulfurization wastewater is preferably obtained by the following process: acid leaching and desulfurization of lithium slag. The process conditions for the lithium slag acid leaching desulfurization wastewater are not limited; any method well-known to those skilled in the art can be used.

[0022] In this invention, the cations in the sulfuric acid-containing waste liquid in step (1) preferably include H+. + Li + Na + Al 3+ Fe 2+ Fe 3+ Ca 2+ Mg 2+ One or more of the following; the anions in the sulfuric acid-containing waste liquid in step (1) preferably include SO42-. 2- .

[0023] In this invention, the preferred method of convection in step (1) is that sulfuric acid waste liquid and water flow in and out in opposite directions in the membrane acid recovery system.

[0024] In this invention, the membrane-based acid recovery system in step (1) preferably includes an acid inlet, a water inlet, an acid outlet, and a water outlet. The acid inlet is used to feed lithium slag desulfurization liquid, the water inlet is used to feed water, the acid outlet is used to obtain desulfurized lithium slag liquid after deacidification, and the water outlet is used to obtain recovered acid.

[0025] In this invention, the membrane-based acid recovery system described in step (1) preferably includes a reaction membrane stack, a peristaltic pump, and connecting pipes.

[0026] In this invention, the reaction membrane stack preferably includes one or more of diffusion dialysis membrane units, nanofiltration membrane units, and electrodialysis membrane units, more preferably including diffusion dialysis membrane units, nanofiltration membrane units, or electrodialysis membrane units, and more preferably diffusion dialysis membrane units.

[0027] In this invention, the diffusion dialysis membrane unit preferably includes a plate-and-frame diffusion dialysis membrane unit, a spiral wound diffusion dialysis membrane unit, or a hollow fiber diffusion dialysis membrane unit, more preferably including a plate-and-frame diffusion dialysis membrane unit or a spiral wound diffusion dialysis membrane unit, and even more preferably a plate-and-frame diffusion dialysis membrane unit. Specifically, in the embodiment, the membrane-based acid recovery system uses a plate-and-frame diffusion dialysis device from Shandong Tianwei, and the plate-and-frame diffusion dialysis membrane unit consists of a membrane stack composed of several pairs of ion exchange membranes.

[0028] In this invention, the liquid temperature in the membrane-based acid recovery system described in step (1) is preferably 25~60℃, more preferably 25~45℃, and even more preferably 35℃.

[0029] In this invention, the flow rate of the sulfuric acid waste liquid fed into the membrane acid recovery system in step (1) is preferably 0.6~3.6L / h, more preferably 1~3L / h, and even more preferably 2L / h.

[0030] In this invention, the flow rate of the water in step (1) is preferably 0.8 to 1.5 times that of the sulfuric acid waste liquid, more preferably 1 to 1.5 times, and even more preferably 1.2 times.

[0031] In this invention, the lithium slag desulfurization liquid after deacidification in step (2) is purified with sodium hydroxide and / or sodium carbonate to remove high-valence cations before alkalization polymerization. The preparation conditions for the composite flocculant in step (2) are not limited; any method well-known to those skilled in the art can be used.

[0032] In this invention, the evaporation and concentration temperature in step (3) is preferably 70~120℃, more preferably 95~110℃, and even more preferably 105℃.

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment provides a method for the resource-based treatment of sulfuric acid-containing waste liquid, such as... Figure 1 As shown, it includes the following steps: (1) The lithium slag desulfurization liquid (cations including H) + Li + Na + Al 3+ Fe 2+ Fe 3+ Ca 2+ and Mg2+ Anions include SO42-. 2- Pure water and acid are introduced into the raw water chamber and receiving chamber of a plate-and-frame diffusion dialysis unit (Shandong Tianwei) via convection, respectively, through the acid inlet and water inlet. The feed liquid temperature is controlled at 25℃. The acid recovery process is carried out under the conditions of a lithium slag desulfurization liquid flow rate of 1L / h and a lithium slag desulfurization liquid to pure water flow ratio of 1:1. The acid outlet yields the deacidified lithium slag desulfurization liquid remaining after the reaction exchange in the unit, while the water outlet yields the recovered acid. A schematic diagram is shown below. Figure 2 As shown, the acid recovery rate is 80%. (2) The lithium slag desulfurization liquid after deacidification is subjected to alkalization polymerization, evaporation crystallization, filtration and drying in sequence to obtain a composite flocculant; (3) Acid concentration and purification: The recovered acid is evaporated and purified at 95°C to finally obtain reusable recovered acid with a sulfuric acid concentration of 85%.

[0036] Example 2

[0037] This embodiment provides a method for the resource-based treatment of sulfuric acid-containing waste liquid, including the following steps: (1) The lithium slag desulfurization liquid (cations including H) + Li + Na + Al 3+ Fe 2+ Fe 3+ Ca 2+ and Mg 2+ Anions include SO42-. 2- Pure water and acid are introduced into the raw water chamber and receiving chamber of a plate-and-frame diffusion dialysis unit (Shandong Tianwei) via convection, respectively. The feed liquid temperature is controlled at 35℃. The acid recovery process is carried out under the conditions of lithium slag desulfurization liquid flow rate of 2L / h and lithium slag desulfurization liquid to pure water flow rate ratio of 1:1.2. The acid outlet yields the desulfurized lithium slag liquid remaining after the reaction exchange in the unit, while the water outlet yields the recovered acid. The acid recovery rate of the process is 90%. (2) The lithium slag desulfurization liquid after deacidification is subjected to alkalization polymerization, evaporation crystallization, filtration and drying in sequence to obtain a composite flocculant; (3) Acid concentration and purification: The recovered acid is evaporated and purified at 105℃ to finally obtain a reusable recovered acid with a sulfuric acid concentration of 85%.

[0038] Example 3

[0039] This embodiment provides a method for the resource-based treatment of sulfuric acid-containing waste liquid, including the following steps: (1) The lithium slag desulfurization liquid (cations including H) + Li + Na + Al 3+Fe 2+ Fe 3+ Ca 2+ and Mg 2+ Anions include SO42-. 2- Pure water and acid are introduced into the raw water chamber and receiving chamber of a plate and frame diffusion dialysis unit (Shandong Tianwei) via convection, respectively. The feed liquid temperature is controlled at 45℃. The acid recovery process is carried out under the conditions of lithium slag desulfurization liquid flow rate of 3L / h and lithium slag desulfurization liquid to pure water flow rate ratio of 1:1.5. The acid outlet yields the deacidified lithium slag desulfurization liquid remaining after the reaction exchange in the unit, while the water outlet yields the recovered acid. The acid recovery rate of the process is 85%. (2) The lithium slag desulfurization liquid after deacidification is subjected to alkalization polymerization, evaporation crystallization, filtration and drying in sequence to obtain a composite flocculant; (3) Acid concentration and purification: The recovered acid is evaporated and purified at 110℃ to finally obtain a reusable recovered acid with a sulfuric acid concentration of 85%.

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the resource-based treatment of sulfuric acid-containing waste liquid, characterized in that, Includes the following steps: (1) The sulfuric acid-containing waste liquid and water are fed into the membrane acid recovery system by convection to recover the acid and obtain the desulfurized lithium slag liquid and recovered acid after deacidification. (2) The desulfurized lithium slag liquid after deacidification is subjected to alkalization polymerization, evaporation crystallization, filtration and drying in sequence to obtain a composite flocculant; (3) The recovered acid is evaporated and concentrated; There is no specific order between steps (2) and (3).

2. The method according to claim 1, characterized in that, The sulfuric acid-containing waste liquid in step (1) includes one or more of the following: lithium slag acid leaching desulfurization liquid, metal pickling sulfuric acid-containing waste liquid, petroleum refining desulfurization sulfuric acid-containing waste liquid, and dye synthesis sulfuric acid-containing waste liquid; The cations in the sulfuric acid-containing waste liquid in step (1) include H+. + Li + Na + Al 3+ Fe 2+ Fe 3+ Ca 2+ Mg 2+ One or more of the following, wherein the anions in the sulfuric acid-containing waste liquid in step (1) include SO42-. 2- .

3. The method according to claim 1, characterized in that, The convection method described in step (1) is as follows: sulfuric acid waste liquid and water flow in and out in opposite directions in the membrane acid recovery system.

4. The method according to claim 1 or 3, characterized in that, The membrane-based acid recovery system in step (1) includes a reaction membrane stack, a peristaltic pump, and connecting pipes. The reaction membrane stack includes one or more of diffusion dialysis membrane units, nanofiltration membrane units, and electrodialysis membrane units.

5. The method according to claim 4, characterized in that, The diffusion dialysis membrane unit includes a plate-and-frame diffusion dialysis membrane unit, a spiral wound diffusion dialysis membrane unit, or a hollow fiber diffusion dialysis membrane unit.

6. The method according to claim 5, characterized in that, The membrane-based acid recovery system in step (1) includes an acid inlet, a water inlet, an acid outlet, and a water outlet. The acid inlet is used to supply lithium slag desulfurization liquid, the water inlet is used to supply water, the acid outlet is used to obtain desulfurized lithium slag liquid after deacidification, and the water outlet is used to obtain recovered acid.

7. The method according to claim 1, characterized in that, The liquid temperature in the membrane-based acid recovery system described in step (1) is 25~60℃.

8. The method according to claim 1 or 7, characterized in that, The flow rate of the sulfuric acid-containing waste liquid in step (1) into the membrane acid recovery system is 0.6~3.6L / h, and the flow rate of the water in step (1) is 0.8~1.5 times that of the sulfuric acid-containing waste liquid.

9. The method according to claim 1, characterized in that, The evaporation and concentration temperature in step (3) is 70~120℃.

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