CN221051702U

CN221051702U - Wastewater treatment device

Info

Publication number: CN221051702U
Application number: CN202322679247.8U
Authority: CN
Inventors: 何志; 肖松林; 赵聪; 何珂桥
Original assignee: Sichuan Sidaneng Environmental Protection Technology Co ltd
Current assignee: Sichuan Sidaneng Environmental Protection Technology Co ltd
Priority date: 2023-09-29
Filing date: 2023-09-29
Publication date: 2024-05-31
Anticipated expiration: 2033-09-29

Abstract

The utility model discloses a wastewater treatment device which can improve the oxidation treatment effect of wastewater to be treated by an oxidation and hydrogen production system. Comprising the following steps: the oxidation and hydrogen production system comprises a wastewater pretreatment module, an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode is used for carrying out oxidation treatment on wastewater to be treated through anode electrochemical reaction, the cathode is used for hydrogen evolution through cathode electrochemical reaction, an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank, and the wastewater pretreatment module is used for adding chloride into the wastewater to be treated before carrying out oxidation treatment and hydrogen production so as to increase the concentration of chloride ions in the wastewater to be treated.

Description

Wastewater treatment device

Technical Field

The embodiment of the utility model relates to a battery black powder treatment method, waste water treatment equipment and a waste water treatment device.

Background

With the popularization of electronic communication equipment and the high-speed development of the electric automobile industry, the consumption of ternary lithium ion batteries and lithium iron phosphate batteries is greatly increased, and the service lives of the batteries are usually 5-8 years, so that a large number of waste batteries are generated after the service lives are over. At present, a hydrometallurgical scheme can be adopted for waste battery black powder, but the problems of complex process and lower energy-saving and environment-friendly benefits exist.

On the other hand, known electrochemical reactors for wastewater treatment mainly include electrocatalytic oxidation (Electro-CATALYTIC OXIDATION, ECO) reactors and electroflocculation (Electro-coagulation, EC) reactors. Their basic structures are similar, namely, they all comprise an electrolytic cell and a DC power supply, and the anode and the cathode of the electrolytic cell are respectively connected with the anode and the cathode of the DC power supply. Their main difference is that there is a certain difference between the electrode materials and the working mechanism.

Electrocatalytic oxidation (Electro-CATALYTIC OXIDATION, EO) is an oxidation using an anode (typically a titanium-based metal oxide coated electrode) and/or an electric field to generate free radicals that promote oxidative decomposition of contaminants, thereby achieving wastewater treatment. Can be subdivided into direct oxidation and indirect oxidation. The direct oxidation method is to oxidize the pollutant on the anode surface directly to eliminate the pollution. The indirect oxidation method is to decompose the molecular water by an electric field to generate an oxidant such as hydroxyl radical, and the oxidant reacts with pollutants in the wastewater to remove the pollutants.

Electroflocculation (Electro-coagulation, EC) is to dissolve metal ions in an anode (usually an aluminum electrode or a ferroelectric electrode) into wastewater, and generate metal hydroxide through hydrolysis reaction, wherein the metal hydroxide is used as a flocculating agent to coagulate suspended matters and colloid in the wastewater, so that the purpose of removing pollution is achieved. Meanwhile, the hydrogen ions of the cathode are reduced into hydrogen after being subjected to electrons, overflow in a micro-bubble mode, and floccules and oil substances in the wastewater can float to the water surface.

At present, the electrocatalytic oxidation technology and the electric flocculation technology are single in function, and recycling of hydrogen is not realized.

Disclosure of utility model

One of the purposes of the embodiments of the utility model is to provide an improved treatment method of battery black powder and a wastewater treatment device for treating high-pollution wastewater generated in the method, which can not only effectively purify the high-pollution wastewater, but also utilize the high-pollution wastewater to prepare hydrogen, thereby improving energy-saving and environment-friendly benefits.

The second purpose of the embodiment of the utility model is to provide a treatment method for battery black powder and a wastewater treatment device in wastewater treatment equipment, which can improve the oxidation treatment effect of the oxidation and hydrogen production system on wastewater to be treated.

In a first aspect, a method for processing black powder of a battery is provided, including: reacting the battery black powder with a leaching agent to obtain a leaching solution containing a plurality of soluble metal salts, wherein the plurality of soluble metal salts contain lithium; separating the plurality of soluble metal salts, wherein the separation adopts an extraction method, and the raffinate wastewater in which the separated lithium is positioned is obtained; carrying out primary pretreatment on the raffinate wastewater to ensure that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L, and the pH value is 6-9; inputting the wastewater after primary pretreatment into an oxidation and hydrogen production system for oxidation treatment and electrolysis hydrogen production, so as to obtain wastewater after oxidation treatment and electrolysis hydrogen production; performing secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, and ensuring that total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can realize solid-liquid separation with the lithium salt after the subsequent lithium precipitation treatment; carrying out lithium precipitation treatment on the secondary pretreatment wastewater to obtain a lithium precipitate converted from the lithium salt and lithium precipitation treated wastewater, wherein the lithium precipitation treated wastewater mainly contains the other soluble metal salts; performing waste water post-treatment on the lithium-precipitation treated waste water to reach the required waste water discharge and/or recovery standard of the to-be-recovered matter; the oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank.

According to the embodiment of the utility model, the battery black powder mainly comes from ternary lithium anode materials; the leaching agent adopts sulfuric acid solution, and the plurality of soluble metal salts in the leaching solution comprise nickel sulfate, cobalt sulfate, manganese sulfate and lithium sulfate; the extraction method specifically comprises a plurality of extraction liquid separation processes and a plurality of back extraction liquid separation processes; a first extraction and separation step for obtaining a first extract of manganese sulfate and a first raffinate of cobalt salt from the leaching solution, respectively; a second extraction and separation step for obtaining a second extraction liquid of the cobalt sulfate and a second raffinate of the nickel salt from the first raffinate; a third extraction and separation step for obtaining a third extract and a third raffinate of the nickel sulfate from the second raffinate, respectively; a first stripping and separating step for obtaining a first stripping liquid and a first stripping raffinate for obtaining the manganese sulfate from the first extraction liquid; a fourth extraction and separation step for obtaining a fourth extract and a fourth raffinate of the manganese sulfate from the first strip solution, respectively; the second back extraction liquid separation process is used for obtaining a second back extraction liquid and a second back raffinate of the cobalt sulfate from the second extraction liquid, wherein the second back extraction liquid is cobalt sulfate solution; the third extraction and liquid separation process is used for obtaining a third extraction liquid and a third raffinate of the nickel sulfate from the third extraction liquid, wherein the third extraction liquid is nickel sulfate solution; a fourth back extraction and liquid separation process is used for obtaining a fourth back extraction liquid and a fourth back raffinate of the manganese sulfate from the fourth extraction liquid, wherein the fourth back extraction liquid is a manganese sulfate solution; obtaining the raffinate wastewater containing the separated lithium comprises the following steps: mixing the third raffinate and the fourth raffinate to form the raffinate waste water.

According to the embodiment of the utility model, the first extraction and liquid separation process adopts a P204 extractant; the second extraction and liquid separation process adopts a P507 extractant; in the third extraction and liquid separation process, a P507 extractant is adopted; and the fourth extraction and liquid separation process adopts a C272 extractant.

According to the embodiment of the utility model, the primary pretreatment comprises the steps of sequentially carrying out air floatation impurity removal treatment, activated carbon adsorption treatment and first solid-liquid separation filtration treatment on the raffinate wastewater.

According to the embodiment of the utility model, the secondary pretreatment comprises the steps of sequentially carrying out alkali precipitation treatment, second solid-liquid separation filtration treatment, pH value callback treatment, evaporation concentration treatment for sodium sulfate crystallization and third solid-liquid separation filtration treatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, wherein the pH value callback treatment is used for callback the pH value of the wastewater to be treated to 6-7.

According to the embodiment of the utility model, the treatment method of the battery black powder further comprises the step of increasing the concentration of chloride ions in the wastewater after the primary pretreatment before the oxidation treatment and the electrolytic hydrogen production.

According to the embodiment of the utility model, the chloride salt with the mass ratio of the adding amount calculated by sodium chloride to the chemical oxygen demand measured in the wastewater after the primary pretreatment of 1-10 is added and mixed into the wastewater after the primary pretreatment, so that the concentration of chloride ions in the wastewater after the primary pretreatment is increased.

In a second aspect, a wastewater treatment device is provided for treating battery black powder leaching solution raffinate wastewater; the production process of the battery black powder leaching liquid raffinate waste water comprises the following steps: reacting the battery black powder with a leaching agent to obtain a leaching solution containing a plurality of soluble metal salts, wherein the plurality of soluble metal salts contain lithium; separating the plurality of soluble metal salts, wherein the separation adopts an extraction method, and the raffinate wastewater in which the separated lithium is positioned is obtained; it comprises the following steps: the primary pretreatment system is used for carrying out primary pretreatment on the raffinate wastewater, so that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after the primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L, and the pH value is 6-9; the oxidation and hydrogen production system is used for carrying out oxidation treatment and electrolysis hydrogen production on the wastewater after the primary pretreatment so as to obtain wastewater after the oxidation treatment and the electrolysis hydrogen production; the secondary pretreatment system is used for carrying out secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, so that the total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can realize solid-liquid separation with the lithium salt after the subsequent lithium precipitation treatment; the lithium precipitation treatment system is used for carrying out lithium precipitation treatment on the secondary pretreatment wastewater to obtain a lithium precipitate converted from the lithium salt and the lithium precipitation treatment wastewater, wherein the lithium precipitation treatment wastewater mainly contains the other soluble metal salts; the waste water post-treatment system is used for carrying out waste water post-treatment on the waste water after the lithium precipitation treatment so as to achieve the required waste water discharge and/or recovery standard of the to-be-recovered matter; the oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank.

According to the embodiment of the utility model, the battery black powder mainly comes from ternary lithium battery anode materials; the leaching agent adopts sulfuric acid solution, and the plurality of soluble metal salts in the leaching solution comprise nickel sulfate, cobalt sulfate, manganese sulfate and lithium sulfate; the extraction method specifically comprises a plurality of extraction liquid separation processes and a plurality of back extraction liquid separation processes; a first extraction and separation step for obtaining a first extract of manganese sulfate and a first raffinate of cobalt salt from the leaching solution, respectively; a second extraction and separation step for obtaining a second extraction liquid of the cobalt sulfate and a second raffinate of the nickel salt from the first raffinate; a third extraction and separation step for obtaining a third extract and a third raffinate of the nickel sulfate from the second raffinate, respectively; a first stripping and separating step for obtaining a first stripping liquid and a first stripping raffinate for obtaining the manganese sulfate from the first extraction liquid; a fourth extraction and separation step for obtaining a fourth extract and a fourth raffinate of the manganese sulfate from the first strip solution, respectively; the second back extraction liquid separation process is used for obtaining a second back extraction liquid and a second back raffinate of the cobalt sulfate from the second extraction liquid, wherein the second back extraction liquid is cobalt sulfate solution; the third extraction and liquid separation process is used for obtaining a third extraction liquid and a third raffinate of the nickel sulfate from the third extraction liquid, wherein the third extraction liquid is nickel sulfate solution; a fourth back extraction and liquid separation process is used for obtaining a fourth back extraction liquid and a fourth back raffinate of the manganese sulfate from the fourth extraction liquid, wherein the fourth back extraction liquid is a manganese sulfate solution; obtaining the raffinate wastewater containing the separated lithium comprises the following steps: mixing the third raffinate and the fourth raffinate to form the raffinate waste water.

According to an embodiment of the utility model, the oxidation and hydrogen production system comprises a wastewater pretreatment module for adding chloride salt to the wastewater after the primary pretreatment before the oxidation treatment and the electrolytic hydrogen production are carried out so as to increase the concentration of chloride ions in the wastewater after the primary pretreatment.

The basic technical conception of the battery black powder treatment method and the wastewater treatment equipment is as follows: firstly, the lithium is initially extracted into a liquid phase (i.e. raffinate waste water) through the steps of separating the plurality of soluble metal salts, wherein an extraction method is adopted for separation, and raffinate waste water in which the separated lithium is positioned is obtained. And then, carrying out primary pretreatment on the raffinate wastewater to ensure that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after the primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L and the pH value is 6-9, so that the wastewater after primary pretreatment meets the requirements of subsequent oxidation treatment and electrolytic hydrogen production. The chemical oxygen demand (i.e., COD content) in the raffinate wastewater is high, from the organic electrolyte in the cell on the one hand, and from the extractant used in the extraction process on the other hand. And then, inputting the once pretreated wastewater into an oxidation and hydrogen production system for oxidation treatment and electrolysis hydrogen production, wherein the oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, the anode and the cathode of the electrolytic tank are respectively connected with the anode and the cathode of the direct current power supply, the anode performs oxidation treatment on the once pretreated wastewater through an anode electrochemical reaction, and the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank. And then, carrying out secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, so as to ensure that the total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can realize solid-liquid separation with the lithium salt after the subsequent lithium precipitation treatment, thereby being beneficial to improving the recovery rate of lithium. And then carrying out lithium precipitation treatment on the wastewater after the secondary pretreatment, and carrying out wastewater post treatment on the wastewater after the lithium precipitation treatment so as to reach the required wastewater discharge and/or recovery standard of the to-be-recovered matters. Therefore, the treatment method of the battery black powder and the wastewater treatment equipment can effectively purify the raffinate wastewater of the battery black powder leaching liquid, and improve the energy-saving and environment-friendly benefits.

In a third aspect, a method for processing black powder of a battery is provided, including: reacting the battery black powder with a leaching agent to obtain leaching liquid containing various soluble metal salts, wherein the soluble metal salts contain lithium; separating the plurality of soluble metal salts, wherein a precipitation method is adopted in the separation, and a precipitation mother solution in which the separated lithium is positioned is obtained; carrying out primary pretreatment on the precipitation mother liquor to ensure that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after the primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L, and the pH value is 6-9; inputting the wastewater after the primary pretreatment into an oxidation treatment and hydrogen production system for oxidation treatment and hydrogen production by electrolysis, so as to obtain wastewater after the oxidation treatment and hydrogen production by electrolysis; performing secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, and ensuring that total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can be separated from the lithium salt after the subsequent lithium precipitation treatment; carrying out lithium precipitation treatment on the secondary pretreatment wastewater to obtain a lithium precipitate converted from the lithium salt and lithium precipitation treated wastewater, wherein the lithium precipitation treated wastewater mainly contains the other soluble metal salts; performing waste water post-treatment on the lithium-precipitation treated waste water to reach the required waste water discharge and/or recovery standard of the to-be-recovered matter; the oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank.

According to the embodiment of the utility model, the battery black powder mainly comes from lithium iron phosphate anode materials; the leaching agent adopts sulfuric acid solution, and lithium iron phosphate in the battery black powder is decomposed into lithium ions, iron ions and phosphate ions in the sulfuric acid solution; the precipitation method specifically comprises the steps of reacting the leaching solution with a mixed solution of sodium hydroxide and hydrogen peroxide to enable the iron ions and the phosphate ions to react to generate ferric phosphate precipitates; the precipitation mother liquor from which the separated lithium is obtained comprises: and carrying out solid-liquid separation on the reaction liquid obtained after the leaching liquid reacts with the mixed solution of sodium hydroxide and hydrogen peroxide, and using the liquid phase obtained after the solid-liquid separation as the precipitation mother liquor.

According to an embodiment of the present utility model, the precipitation mother liquor where the separated lithium is located further comprises: washing the ferric phosphate precipitate after solid-liquid separation by water, sequentially performing alkali precipitation treatment, first solid-liquid separation filtration treatment and reverse osmosis membrane filtration treatment on the washed washing water, and then mixing a concentrated solution generated by the reverse osmosis membrane filtration treatment with the liquid phase to obtain the precipitation mother solution.

According to the embodiment of the utility model, the primary pretreatment comprises the steps of sequentially carrying out alkali precipitation treatment, second solid-liquid separation filtration treatment, pH value callback treatment and evaporation concentration treatment on the precipitation mother liquor, wherein the pH value callback treatment is used for callback the pH value of wastewater to be treated to 6-7.

According to the embodiment of the utility model, the secondary pretreatment comprises the steps of sequentially carrying out evaporation concentration treatment for sodium sulfate crystallization, freezing crystallization treatment for sodium sulfate crystallization and third solid-liquid separation filtration treatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production.

According to the embodiment of the utility model, the method further comprises the step of increasing the concentration of chloride ions in the wastewater after the primary pretreatment before the oxidation treatment and the electrolytic hydrogen production.

In a fourth aspect, a wastewater treatment apparatus is provided for treatment of a battery black powder leachate precipitation mother liquor; the generation process of the battery black powder leaching solution precipitation mother solution comprises the following steps: reacting the battery black powder with a leaching agent to obtain a leaching solution containing a plurality of soluble metal salts, wherein the plurality of soluble metal salts contain lithium; separating the plurality of soluble metal salts, wherein a precipitation method is adopted in the separation, and a precipitation mother solution in which the separated lithium is positioned is obtained; it comprises the following steps: the primary pretreatment system is used for carrying out primary pretreatment on the raffinate wastewater, so that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after the primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L, and the pH value is 6-9; the oxidation and hydrogen production system is used for carrying out oxidation treatment and electrolysis hydrogen production on the wastewater after the primary pretreatment so as to obtain wastewater after the oxidation treatment and the electrolysis hydrogen production; the secondary pretreatment system is used for carrying out secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, so that the total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can realize solid-liquid separation with the lithium salt after the subsequent lithium precipitation treatment; the lithium precipitation treatment system is used for carrying out lithium precipitation treatment on the secondary pretreatment wastewater to obtain a lithium precipitate converted from the lithium salt and the lithium precipitation treatment wastewater, wherein the lithium precipitation treatment wastewater mainly contains the other soluble metal salts; the waste water post-treatment system is used for carrying out waste water post-treatment on the waste water after the lithium precipitation treatment so as to achieve the required waste water discharge and/or recovery standard of the to-be-recovered matter; the oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank.

According to the embodiment of the utility model, the battery black powder mainly comes from lithium iron phosphate anode materials; the leaching agent adopts sulfuric acid solution, and lithium iron phosphate in the battery black powder is decomposed into lithium ions, iron ions and phosphate ions in the sulfuric acid solution; the precipitation method specifically comprises the steps of reacting the leaching solution with a mixed solution of sodium hydroxide and hydrogen peroxide to enable the iron ions and the phosphate ions to react to generate ferric phosphate precipitates; the precipitation mother liquor from which the separated lithium is obtained comprises: carrying out solid-liquid separation on the reaction liquid obtained after the leaching liquid reacts with the mixed solution of sodium hydroxide and hydrogen peroxide, and using a liquid phase obtained through the solid-liquid separation as the precipitation mother liquor; the precipitation mother liquor from which the separated lithium is obtained further comprises: washing the ferric phosphate precipitate after solid-liquid separation by water, sequentially performing alkali precipitation treatment, first solid-liquid separation filtration treatment and reverse osmosis membrane filtration treatment on the washed washing water, and then mixing a concentrated solution generated by the reverse osmosis membrane filtration treatment with the liquid phase to obtain the precipitation mother solution.

The basic technical conception of the battery black powder treatment method and the wastewater treatment equipment is as follows: first, lithium is initially extracted into a liquid phase (i.e., a precipitation mother liquor) by a step of separating the plurality of soluble metal salts by a precipitation method and obtaining a precipitation mother liquor in which the separated lithium is located. And then, carrying out primary pretreatment on the raffinate wastewater to ensure that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after the primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L and the pH value is 6-9, so that the wastewater after primary pretreatment meets the requirements of subsequent oxidation treatment and electrolytic hydrogen production. The chemical oxygen demand (i.e., COD content) in the precipitation mother liquor is high, mainly from the organic electrolyte in the cell. And then, inputting the once pretreated wastewater into an oxidation and hydrogen production system for oxidation treatment and electrolysis hydrogen production, wherein the oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, the anode and the cathode of the electrolytic tank are respectively connected with the anode and the cathode of the direct current power supply, the anode performs oxidation treatment on the once pretreated wastewater through an anode electrochemical reaction, and the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank. And then, carrying out secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, so as to ensure that the total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can realize solid-liquid separation with the lithium salt after the subsequent lithium precipitation treatment, thereby being beneficial to improving the recovery rate of lithium. And then carrying out lithium precipitation treatment on the wastewater after the secondary pretreatment, and carrying out wastewater post treatment on the wastewater after the lithium precipitation treatment so as to reach the required wastewater discharge and/or recovery standard of the to-be-recovered matters. Therefore, the battery black powder treatment method and the wastewater treatment equipment can effectively purify the battery black powder leaching solution precipitation mother liquor, and improve the energy-saving and environment-friendly benefits.

In a fifth aspect, there is provided a wastewater treatment apparatus comprising: the oxidation and hydrogen production system comprises a wastewater pretreatment module, an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode is used for carrying out oxidation treatment on wastewater to be treated through anode electrochemical reaction, the cathode is used for hydrogen evolution through cathode electrochemical reaction, an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank, and the wastewater pretreatment module is used for adding chloride into the wastewater to be treated before carrying out oxidation treatment and hydrogen production so as to increase the concentration of chloride ions in the wastewater to be treated.

According to the embodiment of the utility model, the wastewater pretreatment module comprises a chloride salt solution preparation unit, a metering control unit and a chloride salt solution conveying unit, wherein the chloride salt solution preparation unit is used for preparing a chloride salt solution with a required concentration, the chloride salt solution conveying unit is used for conveying the chloride salt solution to the wastewater to be treated so as to mix the chloride salt solution with the wastewater to be treated, and the metering control unit is used for metering and controlling the adding amount of the chloride salt in the wastewater to be treated.

According to the embodiment of the utility model, the metering control unit is used for controlling the adding amount of the chloride salt in the wastewater to be treated to be 1-10 in terms of mass ratio of sodium chloride to the chemical oxygen demand measured in the wastewater to be treated.

According to an embodiment of the present utility model, a wastewater treatment apparatus includes: the main cylinder body is internally provided with an electrolysis zone and an air flotation zone which are sequentially arranged from bottom to top, a first output port which is correspondingly communicated with the lower part of the electrolysis zone, an input port which is correspondingly communicated with the upper part of the electrolysis zone and a second output port which is correspondingly communicated with the upper part of the air flotation zone are respectively arranged on the main cylinder body, and the electrolysis zone forms the electrolytic tank; the electrolysis device comprises the direct current power supply, and an anode and a cathode which are arranged in the electrolysis zone at intervals, wherein the anode and the cathode are respectively connected with the anode and the cathode of the direct current power supply; the hydrogen recovery device comprises gas isolation parts which are in one-to-one correspondence with the cathodes, the gas isolation parts are sleeved outside the corresponding cathodes and are provided with side walls arranged around the cathodes and end covers positioned at the upper ends of the side walls, the lower ends of the side walls are provided with openings and/or membrane materials which are adopted by the side walls and can permeate ions and water but can not permeate bubbles, the end covers are provided with exhaust ports, the exhaust ports are used for being connected with a hydrogen storage tank through exhaust pipes, and the exhaust pipes are used as exhaust structures; an oxygen floating channel formed by a space between an anode of the electrolysis device and the hydrogen recovery device for introducing oxygen generated by the anode upward into an air floating zone; the floating foam cleaning mechanism is arranged at the top of the air floating zone and is used for discharging floating foam generated at the top of the air floating zone from the second output port; and when the outlet of the chlorine salt solution conveying unit stretches into the electrolysis zone to be conducted with the electrolysis zone, the outlet of the chlorine salt solution conveying unit is positioned at the upper part of the electrolysis zone and outputs chlorine salt solution downwards and/or is positioned at the lower part of the electrolysis zone and outputs chlorine salt solution upwards.

According to an embodiment of the present utility model, a wastewater treatment apparatus includes: the main cylinder body is internally provided with an electrolysis zone and an air flotation zone which are sequentially arranged from bottom to top, a first output port which is correspondingly communicated with the lower part of the electrolysis zone, an input port which is correspondingly communicated with the upper part of the electrolysis zone and a second output port which is correspondingly communicated with the upper part of the air flotation zone are respectively arranged on the main cylinder body, and the electrolysis zone forms the electrolytic tank; the electrolysis device comprises a direct current power supply, and an anode and a cathode which are arranged in the electrolysis zone at intervals, wherein the anode and the cathode are respectively connected with the anode and the cathode of the direct current power supply; the hydrogen recovery device comprises gas isolation parts which are in one-to-one correspondence with the cathodes, the gas isolation parts are sleeved outside the corresponding cathodes and are provided with side walls arranged around the cathodes and end covers positioned at the upper ends of the side walls, the lower ends of the side walls are provided with openings and/or membrane materials which are adopted by the side walls and can permeate ions and water but can not permeate bubbles, the end covers are provided with exhaust ports, the exhaust ports are used for being connected with a hydrogen storage tank through exhaust pipes, and the exhaust pipes are used as exhaust structures; the aeration device is arranged between the electrolysis area and the air floatation area and is used for aerating in the main cylinder; the floating foam cleaning mechanism is arranged at the top of the air floating zone and is used for discharging floating foam generated at the top of the air floating zone from the second output port; and when the outlet of the chlorine salt solution conveying unit stretches into the electrolysis zone to be conducted with the electrolysis zone, the outlet of the chlorine salt solution conveying unit is positioned at the upper part of the electrolysis zone and outputs chlorine salt solution downwards and/or is positioned at the lower part of the electrolysis zone and outputs chlorine salt solution upwards.

According to the embodiment of the utility model, the outlet of the chlorine salt solution conveying unit is positioned above the aeration device.

According to the embodiment of the utility model, the upper part of the air floating zone is provided with a lateral baffle plate positioned in the main cylinder body and separated from the inner wall of the main cylinder body by a certain distance, and a bottom baffle plate connected between the bottom of the lateral baffle plate and the inner wall of the main cylinder body, the lateral baffle plate and the bottom baffle plate form a notch positioned at the upper side of the air floating zone, and the second output port is arranged on the side wall of the main cylinder body and is communicated with the notch in a lateral direction; the floating foam cleaning mechanism is arranged at the top of the air floating zone and is used for pushing floating foam generated at the top of the air floating zone to the notch.

According to an embodiment of the present utility model, the electrolysis apparatus includes a plurality of the anodes and a plurality of the cathodes, and the anodes and the cathodes are arranged in the electrolysis area at staggered intervals in the horizontal direction.

According to the embodiment of the utility model, the first water distributor is arranged at the upper part of the electrolysis zone, and the water distributor inputs the wastewater to be treated which is input from the input port into the electrolysis zone in a mode of being uniformly distributed on the cross section of the electrolysis zone.

According to the embodiment of the utility model, the chloride salt solution conveying unit outputs the chloride salt solution through the second water distributor extending into the electrolysis zone, and the second water distributor inputs the chloride salt solution into the main cylinder in a mode of being uniformly distributed on the cross section of the electrolysis zone.

The wastewater treatment device is provided with the wastewater pretreatment module, and the wastewater pretreatment module is used for adding chloride salt into the wastewater to be treated before the oxidation treatment and the hydrogen production by electrolysis so as to increase the concentration of chloride ions in the wastewater to be treated, wherein the chloride ions can react with oxygen generated by an anode during electrolysis to generate hypochlorite, and the hypochlorite has a stronger oxidation effect on organic matters in the wastewater to be treated, so that the oxidation treatment effect of the oxidation and hydrogen production system on the wastewater to be treated is enhanced, and the COD content of the wastewater to be treated is remarkably reduced.

The utility model is further described below with reference to the drawings and detailed description. Additional aspects and advantages of the utility model will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the utility model and, together with the description, serve to explain the principles of the utility model.

Fig. 1 is a process flow chart of a method for processing battery black powder according to an embodiment of the utility model.

Fig. 2 is a process flow diagram of a process for generating raffinate waste water from a battery black powder leach solution in the method of fig. 1.

Fig. 3 is a process flow chart of a method for processing battery black powder according to an embodiment of the utility model.

Fig. 4 is a process flow diagram of a process for generating a battery black powder leaching solution precipitation mother liquor in the method shown in fig. 3.

Fig. 5 is a schematic structural diagram of a wastewater treatment apparatus according to an embodiment of the present utility model.

Detailed Description

The present utility model will now be described more fully hereinafter with reference to the accompanying drawings. Those of ordinary skill in the art will be able to implement the utility model based on these descriptions. Before describing the present utility model with reference to the accompanying drawings, it should be noted in particular that:

The technical solutions and technical features provided in the respective sections including the following description may be combined with each other without conflict. Furthermore, the described embodiments, features, and combinations of features can be combined as desired and claimed in any given application.

The embodiments of the utility model that are referred to in the following description are typically only a few, but not all, embodiments, based on which all other embodiments, as would be apparent to one of ordinary skill in the art without the benefit of the present disclosure, are intended to be within the scope of the patent protection.

With respect to terms and units in this specification: the terms "comprising," "including," "having," and any variations thereof, in this specification and the corresponding claims and related parts, are intended to cover a non-exclusive inclusion. Furthermore, other related terms and units may be reasonably construed based on the description provided herein.

Fig. 1 is a process flow chart of a method for processing battery black powder according to an embodiment of the utility model. Fig. 2 is a process flow diagram of a process for generating raffinate waste water from a battery black powder leach solution in the method of fig. 1. As shown in fig. 1-2, a method for processing black powder of a battery includes the following steps.

Step one: and (3) reacting the battery black powder with a leaching agent to obtain leaching liquid containing various soluble metal salts, wherein the various soluble metal salts contain lithium.

Step two: and separating the plurality of soluble metal salts, wherein an extraction method is adopted for separation, and the raffinate wastewater in which the separated lithium is positioned is obtained.

Step three: and (3) carrying out primary pretreatment on the raffinate wastewater to ensure that the concentration of solid suspended matters in the wastewater after primary pretreatment obtained after primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L, and the pH value is 6-9.

Step four: and inputting the wastewater after the primary pretreatment into an oxidation and hydrogen production system for oxidation treatment and electrolysis hydrogen production, so as to obtain wastewater after the oxidation treatment and the electrolysis hydrogen production. The oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank.

Step five: and carrying out secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, so as to ensure that total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can realize solid-liquid separation with the lithium salt after the subsequent lithium precipitation treatment.

Step six: and carrying out lithium precipitation treatment on the secondary pretreatment wastewater to obtain a lithium precipitate converted from the lithium salt and the lithium precipitation treatment wastewater, wherein the lithium precipitation treatment wastewater mainly contains the other soluble metal salts.

Step seven: and carrying out waste water post-treatment on the waste water after the lithium precipitation treatment to reach the required waste water discharge and/or recovery standard of the to-be-recovered matter.

Specifically, as shown in fig. 2, in this embodiment, the battery black powder is mainly derived from ternary lithium positive electrode material; the leaching agent adopts sulfuric acid solution, and the plurality of soluble metal salts in the leaching solution comprise nickel sulfate, cobalt sulfate, manganese sulfate and lithium sulfate; the extraction method specifically comprises a plurality of extraction liquid separation processes and a plurality of back extraction liquid separation processes; wherein, the first extraction and liquid separation procedure is used for respectively obtaining a first extraction liquid for obtaining the manganese sulfate and a first raffinate for retaining the nickel salt and the cobalt salt from the leaching liquid; a second extraction and separation step for obtaining a second extraction liquid of the cobalt sulfate and a second raffinate of the nickel sulfate from the first raffinate; a third extraction and separation step for obtaining a third extract and a third raffinate of the nickel sulfate from the second raffinate, respectively; a first stripping and separating step for obtaining a first stripping liquid and a first stripping raffinate for obtaining the manganese sulfate from the first extraction liquid; a fourth extraction and separation step for obtaining a fourth extract and a fourth raffinate of the manganese sulfate from the first strip solution, respectively; the second back extraction liquid separation process is used for obtaining a second back extraction liquid and a second back raffinate of the cobalt sulfate from the second extraction liquid, wherein the second back extraction liquid is cobalt sulfate solution; the third extraction and liquid separation process is used for obtaining a third extraction liquid and a third raffinate of the nickel sulfate from the third extraction liquid, wherein the third extraction liquid is nickel sulfate solution; a fourth back extraction and liquid separation process is used for obtaining a fourth back extraction liquid and a fourth back raffinate of the manganese sulfate from the fourth extraction liquid, wherein the fourth back extraction liquid is a manganese sulfate solution; obtaining the raffinate wastewater containing the separated lithium comprises the following steps: mixing the third raffinate and the fourth raffinate to form the raffinate waste water.

Specifically, the first extraction and liquid separation process adopts a P204 extractant; the second extraction and liquid separation process adopts a P507 extractant; in the third extraction and liquid separation process, a P507 extractant is adopted; and the fourth extraction and liquid separation process adopts a C272 extractant. The P204 extractant, the P507 extractant and the C272 extractant are existing extractants, the names and codes of which are known, and the extractants can introduce organic matters, thereby increasing the treatment difficulty of the raffinate and the wastewater of the black powder leaching solution of the battery.

The method of treating the battery black powder of the present embodiment will be described in further detail with reference to fig. 1.

In the third step, first, the raffinate waste water (i.e. the raffinate waste water of the black powder leaching solution of the battery) enters the air floatation tank 11 for air floatation and impurity removal treatment, and the air floatation tank 11 is an existing sewage treatment device which mainly uses a large number of microbubbles to capture and adsorb fine particle adhesives to float upwards, so as to achieve the effect of solid-liquid separation. Here, the main purpose of the floatation tank 11 is to remove most of the SS (suspended solids), oils and COD in the raffinate wastewater. Thereafter, the raffinate wastewater output by the air floatation tank 11 enters an activated carbon decoloring device 12, and the activated carbon decoloring device 12 is used for adsorbing impurities in the wastewater by using activated carbon so as to further remove SS, oil and COD in the raffinate wastewater. And then, sequentially carrying out solid-liquid separation on the raffinate wastewater output by the activated carbon decoloring device 12 through a filter press 13 and a precise filter 14 (adopting a microfiltration filter), and obtaining the wastewater subjected to primary pretreatment, wherein the concentration of solid suspended matters is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L and the pH value is 6-9.

In the fourth step, the oxidation and hydrogen production system 21 comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after the primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank. Wherein, the anode can be the same or similar to an electrocatalytic oxidation reactor (such as a titanium-based metal oxide coating electrode), and the cathode can be the same or similar to an electrocoagulation reactor (so as to facilitate hydrogen evolution).

In an alternative embodiment, the oxidation and hydrogen production system 21 includes a wastewater pretreatment module for adding chloride salt to the once pretreated wastewater to increase chloride ion concentration in the once pretreated wastewater prior to performing the oxidation treatment and electrolytic hydrogen production. The chlorine ions can react with oxygen generated by the anode during electrolysis to generate hypochlorite, and the hypochlorite has a strong oxidation effect on organic matters in the wastewater to be treated, so that the oxidation treatment effect of the oxidation and hydrogen production system on the wastewater to be treated is enhanced, and the COD content of the wastewater to be treated is remarkably reduced.

In general, the increase in chloride ion concentration in the wastewater after the primary pretreatment is achieved by adding and mixing a chloride salt in an amount of 1 to 10 in terms of sodium chloride to the mass ratio of the chemical oxygen demand measured in the wastewater after the primary pretreatment. In this example, sodium chloride is used as the chlorine salt, and the mass ratio of the added amount of sodium chloride to the chemical oxygen demand measured in the wastewater after the primary pretreatment is 3.

In the fifth step, firstly, the wastewater after the oxidation treatment and the electrolysis hydrogen production enters a pH adjusting tank 31, and the pH adjusting tank 31 has the function of adding alkali into the wastewater after the oxidation treatment and the electrolysis hydrogen production so as to improve the pH value of the wastewater after the oxidation treatment and the electrolysis hydrogen production. In this embodiment, the pH value of the wastewater after the oxidation treatment and the electrolytic hydrogen production in the pH adjustment tank 31 is adjusted to 11. Thus, the nickel, cobalt, manganese, copper and other metal ions in the wastewater after the oxidation treatment and the electrolytic hydrogen production are separated out in the form of hydroxide precipitation. After that, the wastewater after the oxidation treatment and the electrolytic hydrogen production outputted from the pH adjusting tank 31 is sequentially passed through a filter press 32 and a precision filter 33 (a microfiltration filter is used) to realize solid-liquid separation. After that, the wastewater after the oxidation treatment and the electrolysis hydrogen production outputted from the fine filter 33 enters a pH adjusting tank 34, and the pH value of the wastewater after the oxidation treatment and the electrolysis hydrogen production is adjusted to 6-7 (sulfuric acid is added) in the pH adjusting tank 34, so that the purpose of the subsequent recovery of sodium sulfate is achieved. After that, the wastewater after the oxidation treatment and the electrolytic hydrogen production sequentially passes through an evaporation concentration crystallizer 35 and a thickener 36, the evaporation concentration crystallizer 35 specifically adopts an MVR evaporation concentration crystallization device, the concentration multiple is 5, so that sodium sulfate in the wastewater after the oxidation treatment and the electrolytic hydrogen production is crystallized and separated out, and then the solid-liquid separation is realized through a centrifugal separator 37. The obtained total soluble solid matter (expressed by TDS content) mainly contains lithium salt and other soluble metal salt which can realize solid-liquid separation from the lithium salt after subsequent lithium precipitation treatment.

In the sixth step, the wastewater after the secondary pretreatment is input into a lithium precipitation reactor 41, and lithium carbonate is generated by the reaction of sodium carbonate added into the lithium precipitation reactor 41 and lithium ions in the wastewater after the secondary pretreatment. The solid-liquid separation is then effected by means of a centrifugal separator 42.

In the seventh step, the waste water after the lithium precipitation treatment is acidified by a mother liquor acidifier 51, and then the mixed salt is obtained by roller drying.

The material balance table of each step of the treatment method of the battery black powder of the above example is shown in tables 1 and 2 (the material balance table is split into tables 1 and 2).

Table 1:

Table 2:

Fig. 3 is a process flow chart of a method for processing battery black powder according to an embodiment of the utility model. Fig. 4 is a process flow diagram of a process for generating a battery black powder leaching solution precipitation mother liquor in the method shown in fig. 3. As shown in fig. 3 to 4, a method for treating black powder of a battery includes the following steps.

Step one: and (3) reacting the battery black powder with a leaching agent to obtain leaching liquid containing various soluble metal salts, wherein the soluble metal salts contain lithium.

Step two: and separating the plurality of soluble metal salts, wherein a precipitation method is adopted for separation, and a precipitation mother solution in which the separated lithium is positioned is obtained.

Step three: and (3) carrying out primary pretreatment on the precipitation mother liquor to ensure that the concentration of solid suspended matters in the wastewater obtained after primary pretreatment is less than or equal to 5mg/L, the oil content is less than or equal to 5mg/L, the chemical oxygen demand is less than or equal to 500mg/L, and the pH value is 6-9.

Step four: and inputting the wastewater after the primary pretreatment into an oxidation treatment and hydrogen production system for oxidation treatment and hydrogen production by electrolysis, thereby obtaining wastewater after the oxidation treatment and hydrogen production by electrolysis. The oxidation and hydrogen production system comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank.

Step five: and carrying out secondary pretreatment on the wastewater after the oxidation treatment and the electrolytic hydrogen production, so as to ensure that the total soluble solid matters in the wastewater after the secondary pretreatment obtained after the secondary pretreatment mainly contain lithium salt and other soluble metal salts which can be separated from the lithium salt after the subsequent lithium precipitation treatment.

Specifically, as shown in fig. 4, in this embodiment, the battery black powder is mainly derived from lithium iron phosphate positive electrode material; the leaching agent adopts sulfuric acid solution, and lithium iron phosphate in the battery black powder is decomposed into lithium ions, iron ions and phosphate ions in the sulfuric acid solution; the precipitation method specifically comprises the steps of reacting the leaching solution with a mixed solution of sodium hydroxide and hydrogen peroxide to enable the iron ions and the phosphate ions to react to generate ferric phosphate precipitates; the precipitation mother liquor from which the separated lithium is obtained comprises: and carrying out solid-liquid separation on the reaction liquid obtained after the leaching liquid reacts with the mixed solution of sodium hydroxide and hydrogen peroxide, and using the liquid phase obtained after the solid-liquid separation as the precipitation mother liquor. In addition, the precipitation mother liquor from which the separated lithium is obtained further comprises: washing the ferric phosphate precipitate after solid-liquid separation by water, sequentially performing alkali precipitation treatment, first solid-liquid separation filtration treatment and reverse osmosis membrane filtration treatment on the washed washing water, and then mixing a concentrated solution generated by the reverse osmosis membrane filtration treatment with the liquid phase to obtain the precipitation mother solution. Clear liquid generated by the reverse osmosis membrane filtration treatment can be recycled.

The principle that lithium iron phosphate in the battery black powder is decomposed into lithium ions, iron ions and phosphate ions in the sulfuric acid solution can be expressed as follows:

LiFePO₄+H₂SO₄→Li⁺+Fe²⁺+PO₄ ^3-+SO₄ ^2-+H₂0.

The principle of reacting the leachate with a mixed solution of sodium hydroxide and hydrogen peroxide to react the iron ions with the phosphate ions to generate ferric phosphate precipitates can be expressed as follows:

Li⁺+Fe²⁺+PO₄ ^3-+SO₄ ^2-+NaOH+H₂0₂→FeP0₄(s)+Na₂SO₄+Li₂SO₄+H₂0.

The method of treating the battery black powder of the present embodiment will be described in further detail with reference to fig. 3.

In the third step, firstly, the precipitation mother liquor sequentially enters a flocculation precipitation system A61 and a flocculation precipitation system B63 (a filter press and a precise filter 62 are further sequentially arranged between the flocculation precipitation system A61 and the flocculation precipitation system B63, the filter press is not shown in the drawing), the flocculation precipitation system A61 precipitates and separates out metal ions such as iron, aluminum and the like in the precipitation mother liquor by adding sodium hydroxide, calcium hydroxide, hydrogen peroxide and PAM flocculant, and the flocculation precipitation system B63 precipitates and separates out metal ions such as magnesium, copper and the like in the precipitation mother liquor by adding the sodium hydroxide and the PAM flocculant. Then sequentially passing through a filter press (not shown), a precision filter 64 and a pH adjusting tank 65 (pH is adjusted to about 6) to obtain wastewater after primary pretreatment.

In the fourth step, the oxidation and hydrogen production system 71 comprises an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode performs oxidation treatment on the wastewater after the primary pretreatment through an anode electrochemical reaction, the cathode performs hydrogen evolution through a cathode electrochemical reaction, and an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank. Wherein, the anode can be the same or similar to an electrocatalytic oxidation reactor (such as a titanium-based metal oxide coating electrode), and the cathode can be the same or similar to an electrocoagulation reactor (so as to facilitate hydrogen evolution).

In an alternative embodiment, the oxidation and hydrogen production system 71 includes a wastewater pretreatment module for adding chloride salt to the once pretreated wastewater to increase chloride ion concentration in the once pretreated wastewater prior to performing the oxidation treatment and electrolytic hydrogen production. The chlorine ions can react with oxygen generated by the anode during electrolysis to generate hypochlorite, and the hypochlorite has a strong oxidation effect on organic matters in the wastewater to be treated, so that the oxidation treatment effect of the oxidation and hydrogen production system on the wastewater to be treated is enhanced, and the COD content of the wastewater to be treated is remarkably reduced.

In the fifth step, the wastewater after the oxidation treatment and the electrolytic hydrogen production is subjected to the evaporation concentration treatment for sodium sulfate crystallization and the freezing crystallization treatment for sodium sulfate crystallization by sequentially passing through the evaporation concentration crystallizer 81 and the freezing crystallization 82, and then is subjected to the solid-liquid separation by passing through the centrifugal separator 83. The obtained total soluble solid matter (expressed by TDS content) mainly contains lithium salt and other soluble metal salt which can realize solid-liquid separation from the lithium salt after subsequent lithium precipitation treatment.

In the sixth step, the wastewater after the secondary pretreatment is input into a lithium precipitation reactor 91, and lithium carbonate is generated by the reaction of sodium carbonate added into the lithium precipitation reactor 91 and lithium ions in the wastewater after the secondary pretreatment. The solid-liquid separation is then effected by a centrifugal separator 92.

And step seven, acidizing the wastewater after lithium precipitation treatment by a mother liquor acidifier, and then drying by a roller to obtain the mixed salt.

The material balance table of each step of the treatment method of the battery black powder of the above example is shown in tables 3 to 5 (the material balance table is split into tables 3 to 5).

Table 3:

table 4:

Table 5:

Fig. 5 is a schematic structural diagram of a wastewater treatment apparatus according to an embodiment of the present utility model. The waste water treatment device can be used for the treatment method of the battery black powder and an oxidation and hydrogen production system in waste water treatment equipment.

The wastewater treatment device comprises a main cylinder 101, an electrolysis device 102, a hydrogen recovery device 103, an aeration device 107 and a froth cleaning mechanism 105; the main cylinder 101 is internally provided with an electrolysis region 1011 and an air flotation region 1012 which are sequentially arranged from bottom to top, and the main cylinder 101 is respectively provided with a first output port 1013 which is correspondingly communicated with the lower part of the electrolysis region 1011, an input port 1014 which is correspondingly communicated with the upper part of the electrolysis region 1011 and a second output port 1015 which is correspondingly communicated with the upper part of the air flotation region 1012; the electrolysis device 102 comprises a direct current power supply 1021, and an anode 1022 and a cathode 1023 which are arranged in the electrolysis region 1011 at intervals, wherein the anode 1022 and the cathode 1023 are respectively connected with the positive electrode and the negative electrode of the direct current power supply 1021, and when in operation, the anode 1022 performs oxidation treatment on wastewater entering the electrolysis region 1011 through the input port 1014 through an anode electrochemical reaction, and the cathode 1023 generates hydrogen through a cathode electrochemical reaction; the hydrogen recovery device 103 comprises gas isolation components corresponding to the cathodes 1023 one by one, the gas isolation components are sleeved outside the corresponding cathodes 1023 and provided with side walls 1031 and end covers 1032 positioned at the upper ends of the side walls 1031, the lower ends of the side walls 1031 are provided with openings and/or membrane materials (such as membranes used in alkaline water electrolysis hydrogen production) which are used by the side walls 1031 and can not permeate ions and water but can not permeate bubbles, the end covers 1032 are provided with exhaust ports, and the exhaust ports are used for being connected with a hydrogen storage tank through exhaust pipes 1033; the aeration device 107 is arranged between the electrolysis area 1011 and the air floatation area 1012 and is used for aeration in the main cylinder 101; the froth cleaning mechanism 105 is mounted on the top of the air flotation area 1012, and is used for discharging froth generated on the top of the air flotation area 1012 from the second output port 1015.

In addition, the above-mentioned wastewater treatment apparatus further comprises a wastewater pretreatment module 108, wherein the wastewater pretreatment module 108 is used for adding chloride salt to the wastewater to be treated before performing oxidation treatment and electrolytic hydrogen production so as to increase the concentration of chloride ions in the wastewater to be treated. Specifically, the wastewater pretreatment module 18 includes a chlorine salt solution preparation unit for preparing a chlorine salt solution (for example, a sodium chloride solution) of a desired concentration, a metering control unit for delivering the chlorine salt solution to the wastewater to be treated so as to mix the chlorine salt solution with the wastewater to be treated, and a chlorine salt solution delivery unit for metering and controlling the addition amount of the chlorine salt in the wastewater to be treated. In general, the metering control unit is used for controlling the addition amount of the chloride salt in the wastewater to be treated to be 1-10 in terms of sodium chloride and the mass ratio of the chemical oxygen demand measured in the wastewater to be treated.

The working principle of the wastewater purification treatment and hydrogen production system is as follows: wastewater to be treated enters the main cylinder 101 through the input port 1014, at the same time, a chlorine salt solution is added into the wastewater to be treated by the wastewater pretreatment module 108, and a large amount of bubbles generated by aeration of the aeration device 107 (usually by air aeration) are combined back and forth with the wastewater to be treated entering the main cylinder 101 through the input port 1014, the bubbles adhere to suspended particles in the wastewater to be treated, the suspended particles float up on the surface of the air-floating area 1012 by buoyancy to form floating foam, the floating foam is then discharged from the second output port 1015 by the floating foam cleaning mechanism 105 and can enter the defoaming device for further treatment, the chlorine salt solution and the wastewater to be treated can be fully mixed by aeration, after that, the wastewater enters the electrolysis area 1011 downwards from the air-floating area 1012, when the electrolysis device 102 works, the anode 1022 performs oxidation treatment on the wastewater entering the electrolysis region 1011 through the input port 1014 through the anode electrochemical reaction (the anode 1022 generates oxygen bubbles, the oxygen bubbles react with chloride ions added by the wastewater pretreatment module 108 to generate hypochlorite, the hypochlorite has a strong oxidation effect on organic matters in the wastewater to be treated, so that the oxidation treatment effect of the oxidation and hydrogen production system on the wastewater to be treated is enhanced, the COD content of the wastewater to be treated is remarkably reduced), the cathode 1023 generates hydrogen through the cathode electrochemical reaction, at this time, the hydrogen is collected through a gas isolation part and is led into a hydrogen storage tank through an exhaust pipe 1033, and materials (usually a mixture of water and solid slag) at the lower part of the electrolysis region 1011 are discharged from the first output port 1013.

In the electrolyzer 102, the anode 1022 may be the same or similar anode as the electrocatalytic oxidation reactor (e.g., titanium-based oxide-coated electrode), and the cathode 1023 may be the same or similar cathode as the electrocoagulation reactor (to facilitate hydrogen evolution). Generally, the electrolyzer 102 comprises a plurality of anodes 1022 and a plurality of cathodes 1023, and the anodes 1022 and the cathodes 1023 are arranged in the electrolysis area 1011 at intervals in a horizontal direction.

In an alternative embodiment, the main cylinder 101 further has a settling zone 1016 located in the lower portion of the electrolysis zone 1011, and typically, the bottom of the settling zone 116 forms a conical discharge chute, and the slag discharge port is located in the bottom of the conical discharge chute.

The froth cleaning mechanism 105 may be a scraper. In addition, in order to facilitate the treatment of the froth, the upper portion of the air-floating area 1012 is provided with a lateral partition board located inside the main cylinder 101 and spaced from the inner wall of the main cylinder 101 by a certain distance, and a bottom partition board connected between the bottom of the lateral partition board and the inner wall of the main cylinder 101, the lateral partition board and the bottom partition board form a notch 1016 located at an upper position of the lateral surface of the air-floating area, and the second output port 1015 is arranged on the side wall of the main cylinder 101 and is laterally communicated with the notch 1016; the froth cleaning mechanism 105 is mounted on top of the air bearing zone and is configured to push froth generated at the top of the air bearing zone toward the gap 1016.

Because the froth mainly contains suspended particles and bubbles, the froth has poor fluidity and is easy to block a pipeline. By the above design, the floating foam cleaned by the floating foam cleaning mechanism 105 (scraper) can be pushed into the notch 1016 for temporary storage, and then the second output port 1015 at the side of the notch 1016 is used as an overflow port, so that the floating foam naturally flows out of the second output port 1015, and the second output port 1015 is prevented from being blocked. In addition, the design can also enable the upper part of the main cylinder 101 to be integrally sealed outside the second output port 1015, thereby reducing noise, reducing potential safety hazard and improving the appearance aesthetic property of the equipment.

In an alternative embodiment, a water distributor 106 is arranged at the upper part of the electrolysis zone 1011, and the water distributor 106 inputs the wastewater to be treated input from the input port 1014 into the electrolysis zone 1011 in a mode of being uniformly distributed on the cross section of the electrolysis zone 1011. Specifically, the water distributor 106 has a main water inlet pipeline connected to the input port 1014 and water distribution manifolds spaced apart on the main water inlet pipeline, the main water inlet pipeline being disposed in a horizontal direction, and the water distribution manifolds being disposed vertically downward.

The aeration device 107 is preferably disposed between the water distributor 106 and the electrolysis device 102. In fig. 5, the aeration device 107 may have a main air inlet line and aeration points spaced apart on the main air inlet line, the main air inlet line being disposed in a horizontal direction and connected to an air source.

The above-described wastewater treatment apparatus may also eliminate the aeration apparatus 107, and achieve an air-floating-like effect by using oxygen bubbles generated by the anode 1022 when the wastewater of the electrolysis region 1011 is subjected to oxidation treatment. The space between the anode of the electrolysis device and the hydrogen recovery device can form an oxygen floating channel, so that oxygen generated by the anode is guided upwards into the air floating zone.

In the above-mentioned wastewater treatment apparatus, the outlet of the chlorine salt solution transporting unit 108 may be connected to the input port 1014 (as shown in fig. 5) or/and extend into the electrolysis region to be connected to the electrolysis region 1011, and when the outlet of the chlorine salt solution transporting unit extends into the electrolysis region to be connected to the electrolysis region, the outlet of the chlorine salt solution transporting unit 108 may be located at an upper portion of the electrolysis region and output the chlorine salt solution downward and/or located at a lower portion of the electrolysis region and output the chlorine salt solution upward. When the outlet of the chlorine salt solution delivery unit extends into the electrolysis zone to be communicated with the electrolysis zone, a structure similar to the water distributor 106 can be adopted to deliver the chlorine salt solution into the main cylinder in a mode of being uniformly distributed on the cross section of the electrolysis zone.

The content of the present utility model is described above. Those of ordinary skill in the art will be able to implement the utility model based on these descriptions. Based on the foregoing specification, all other embodiments that may be obtained by one of ordinary skill in the art without making any inventive effort are intended to be within the scope of patent protection.

Claims

1. A wastewater treatment apparatus, comprising: the oxidation and hydrogen production system comprises a wastewater pretreatment module, an electrolytic tank, a direct current power supply and a hydrogen storage tank, wherein an anode and a cathode of the electrolytic tank are respectively connected with an anode and a cathode of the direct current power supply, the anode is used for carrying out oxidation treatment on wastewater to be treated through anode electrochemical reaction, the cathode is used for hydrogen evolution through cathode electrochemical reaction, an exhaust structure of the electrolytic tank is connected with the hydrogen storage tank, and the wastewater pretreatment module is used for adding chloride into the wastewater to be treated before carrying out oxidation treatment and hydrogen production so as to increase the concentration of chloride ions in the wastewater to be treated.

2. A wastewater treatment plant as claimed in claim 1, wherein: the wastewater pretreatment module comprises a chloride salt solution preparation unit, a metering control unit and a chloride salt solution conveying unit, wherein the chloride salt solution preparation unit is used for preparing a chloride salt solution with a required concentration, the chloride salt solution conveying unit is used for conveying the chloride salt solution to the wastewater to be treated so as to mix the chloride salt solution with the wastewater to be treated, and the metering control unit is used for metering and controlling the adding amount of the chloride salt in the wastewater to be treated.

3. A wastewater treatment plant as claimed in claim 2, wherein: the metering control unit is used for controlling the adding amount of the chloride salt in the wastewater to be treated to be 1-10 in terms of mass ratio of sodium chloride to the chemical oxygen demand measured in the wastewater to be treated.

4. A wastewater treatment plant as claimed in claim 2, wherein: comprising the following steps:

The main cylinder body is internally provided with an electrolysis zone and an air flotation zone which are sequentially arranged from bottom to top, a first output port which is correspondingly communicated with the lower part of the electrolysis zone, an input port which is correspondingly communicated with the upper part of the electrolysis zone and a second output port which is correspondingly communicated with the upper part of the air flotation zone are respectively arranged on the main cylinder body, and the electrolysis zone forms the electrolytic tank;

The electrolysis device comprises the direct current power supply, and an anode and a cathode which are arranged in the electrolysis zone at intervals, wherein the anode and the cathode are respectively connected with the anode and the cathode of the direct current power supply;

The hydrogen recovery device comprises gas isolation parts which are in one-to-one correspondence with the cathodes, the gas isolation parts are sleeved outside the corresponding cathodes and are provided with side walls arranged around the cathodes and end covers positioned at the upper ends of the side walls, the lower ends of the side walls are provided with openings and/or membrane materials which are adopted by the side walls and can permeate ions and water but can not permeate bubbles, the end covers are provided with exhaust ports, the exhaust ports are used for being connected with a hydrogen storage tank through exhaust pipes, and the exhaust pipes are used as exhaust structures;

An oxygen floating channel formed by a space between an anode of the electrolysis device and the hydrogen recovery device for introducing oxygen generated by the anode upward into an air floating zone;

The floating foam cleaning mechanism is arranged at the top of the air floating zone and is used for discharging floating foam generated at the top of the air floating zone from the second output port;

And when the outlet of the chlorine salt solution conveying unit stretches into the electrolysis zone to be conducted with the electrolysis zone, the outlet of the chlorine salt solution conveying unit is positioned at the upper part of the electrolysis zone and outputs chlorine salt solution downwards and/or is positioned at the lower part of the electrolysis zone and outputs chlorine salt solution upwards.

5. A wastewater treatment plant as claimed in claim 2, wherein: comprising the following steps:

the electrolysis device comprises a direct current power supply, and an anode and a cathode which are arranged in the electrolysis zone at intervals, wherein the anode and the cathode are respectively connected with the anode and the cathode of the direct current power supply;

The aeration device is arranged between the electrolysis area and the air floatation area and is used for aerating in the main cylinder;

6. A wastewater treatment plant as claimed in claim 5, wherein: the outlet of the chlorine salt solution conveying unit is positioned above the aeration device.

7. A wastewater treatment plant as claimed in claim 4 or 5, characterized in that: the upper part of the air floating zone is provided with a lateral baffle plate positioned in the main cylinder body and separated from the inner wall of the main cylinder body by a certain distance, and a bottom baffle plate connected between the bottom of the lateral baffle plate and the inner wall of the main cylinder body, the lateral baffle plate and the bottom baffle plate form a notch positioned at the upper side of the air floating zone, and the second output port is arranged on the side wall of the main cylinder body and is laterally communicated with the notch; the floating foam cleaning mechanism is arranged at the top of the air floating zone and is used for pushing floating foam generated at the top of the air floating zone to the notch.

8. A wastewater treatment plant as claimed in claim 4 or 5, characterized in that: the electrolysis device comprises a plurality of anodes and a plurality of cathodes, and the anodes and the cathodes are arranged in the electrolysis area at intervals along the horizontal direction.

9. A wastewater treatment plant as claimed in claim 4 or 5, characterized in that: the upper part of the electrolysis zone is provided with a first water distributor, and the water distributor inputs the wastewater to be treated input from the input port into the electrolysis zone in a mode of being uniformly distributed on the cross section of the electrolysis zone.

10. A wastewater treatment plant as claimed in claim 4 or 5, characterized in that: the chlorine salt solution conveying unit outputs chlorine salt solution through a second water distributor extending into the electrolysis zone, and the second water distributor inputs the chlorine salt solution into the main cylinder in a mode of being uniformly distributed on the cross section of the electrolysis zone.