Method for recycling cobalt in waste heat battery by using bipolar membrane electrodialysis technology and bipolar membrane electrodialysis system

Abstract

The invention discloses a method for recovering cobalt in a waste heat battery by using a bipolar membrane electrodialysis technology, and belongs to the technical field of resource recovery. According to the method, through the steps of waste battery disassembly, positive plate treatment, bipolar membrane electrodialysis treatment, cobalt hydroxide concentrated solution preparation and the like, the waste batteries are used as raw materials, under the action of a bipolar membrane electrodialysis technology, efficient recovery of cobalt is achieved, cobalt hydroxide with the purity being 95.2%-96.2% is prepared, the total yield reaches 95.9%-97.8%, and meanwhile a byproduct sulfuric acid solution is obtained. The method is simple in process, low in equipment investment, low in production cost, high in raw material utilization rate and capable of realizing resource recycling and reducing environmental pollution.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of hot battery resource recycling, and particularly relates to a method for recovering cobalt in waste hot batteries by using a bipolar membrane electrodialysis technology and a bipolar membrane electrodialysis system. BACKGROUND

[0002] As a solid molten salt battery, the traditional treatment method for the hot battery after use is usually incineration and solid waste treatment. If the cobalt and other metal resources cannot be effectively recovered, not only the resources will be wasted, but also the environment will be harmed. Therefore, it is of great practical significance to develop an efficient, environmentally friendly and economical method for recovering cobalt in waste hot batteries.

[0003] In recent years, bipolar membrane electrodialysis (EDBM) technology has been applied to the field of metal recovery from waste batteries. The closest prior art includes: a method for recovering valuable metals from positive electrode waste materials of waste power batteries (CN108517409B), a method for comprehensively recovering valuable metals from lithium ion battery electrode waste materials (CN109402394B), and the like. The purpose of these prior arts is to recover multiple valuable metals, and to pursue high recovery rates of multiple metals, with the recovery rates of nickel, cobalt and manganese lithium being greater than 98% or 99%. However, they have the following shortcomings and are not suitable for efficiently, low-energy and low-pollution recovery of cobalt in waste hot batteries: 1. Complex process and high cost: The existing technologies such as CN108517409B require acid leaching, multi-stage impurity removal, selective co-extraction, deep oil removal and other multi-step treatments, and CN109402394B involves complex processes such as acid leaching, impurity removal, selective precipitation and bipolar membrane electrodialysis, resulting in complicated process, large equipment investment and high energy consumption.

[0004] 2. Insufficient metal separation efficiency and product purity: The existing technologies rely on chemical precipitation or solvent extraction to separate metals, and have problems such as dispersion of lithium resources, poor separation effect of nickel, cobalt and manganese, etc. For example, CN108517409B requires strict control of pH value and extraction stages, and CN109402394B requires accurate control of the amount of reducing agent, otherwise impurities will be easily left.

[0005] 3. Environmental defects are prominent: In the existing technologies (such as CN108517409B), the saponification of organic extractant easily produces high-sodium wastewater, and the chemical precipitation method requires a large amount of acid and alkali reagents, which has the risk of three wastes discharge and does not meet the green recycling requirements.

[0006] 4. Limited adaptability of raw materials: CN108517409B and CN109402394B are mainly aimed at positive electrode waste materials of waste power batteries and electrode waste materials of lithium ion batteries, and do not involve special molten salt battery waste materials such as waste hot batteries, lacking targeted recovery technology. SUMMARY

[0007] This invention aims to provide a method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology. This method enables efficient recovery of cobalt from waste thermal batteries while reducing environmental pollution and energy consumption.

[0008] Firstly, a method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology, as described in this scheme, includes the following steps: S1. Disassembly of waste batteries: Disassemble the waste batteries and remove the positive electrode plates; S2. Positive electrode sheet treatment: Dissolve the positive electrode sheet in water and add sulfuric acid solution. Control the mass ratio of the positive electrode sheet to the volume of pure water and sulfuric acid to be 1:(9~19):(0.2~1) (kg / L). Stir at 20~50℃ for 10~30 minutes, and then filter through a 1~10 micrometer microporous filter to obtain electrodialysis solution. S3. Bipolar Membrane Electrodialysis Treatment: Pump the electrodialysis solution into the feed chamber of the bipolar membrane electrodialysis unit. Pump pure water into the acid and alkali chambers respectively. Add a 5-10% (w / w) sodium sulfate or potassium sulfate solution to the electrode chamber. After starting the equipment, control the current density to 2-20 A / m³. 2 The voltage is 20-50V, and the temperature of the liquid chamber, acid chamber, and alkali chamber is 25-50℃. When the conductivity of the liquid chamber drops to 1500-3000us / cm, the cobalt hydroxide solution in the alkali chamber and the sulfuric acid solution in the acid chamber are collected. S4. Concentration treatment: The cobalt hydroxide solution is pumped into a reverse osmosis concentrator and concentrated to a mass concentration of 15-18% under a gauge pressure of 0.5-0.8 MPa to obtain a cobalt hydroxide concentrate.

[0009] Furthermore, in step S2, the mass ratio of the positive electrode sheet to the volume ratio of pure water and sulfuric acid is 1:15:0.8 (kg / L).

[0010] Furthermore, the current density mentioned in step S3 is 18 A / m. 2 The voltage is 40V.

[0011] Furthermore, in step S3, the temperature of the feed liquid chamber / acid chamber / alkali chamber is controlled at 40°C.

[0012] Furthermore, the concentration of the sulfuric acid solution is 50%.

[0013] Furthermore, the bipolar membrane of the bipolar membrane electrodialysis device is composed of a cation exchange layer, an interfacial hydrophilic layer, and an anion exchange layer.

[0014] Secondly, the present invention also provides a bipolar membrane electrodialysis system for recovering cobalt from waste thermal batteries, characterized in that it includes a bipolar membrane electrodialysis unit, wherein the bipolar membrane electrodialysis unit comprises at least a feed chamber, an acid chamber, an alkali chamber, and an electrode chamber, wherein: The feed chamber is used to contain the electrodialysis solution and is connected to an external pump to input the electrodialysis solution after the waste heat battery positive electrode sheet has been treated. The acid chamber and the alkali chamber are used to contain pure water, and each is connected to a pure water source. The polar chamber is used to contain a sodium sulfate or potassium sulfate solution of a certain concentration; The bipolar membrane electrodialysis device is equipped with a bipolar membrane, which is composed of a cation exchange layer, an interfacial hydrophilic layer and an anion exchange layer, and is used to dissociate water and separate ions under the action of an electric field.

[0015] Furthermore, the bipolar membrane electrodialysis unit also includes an electrode assembly, which provides a voltage of 20–50V to maintain the temperature of the feed chamber, acid chamber, and alkali chamber at 25–50°C and generates 2–20A / m 2 The current density.

[0016] Furthermore, the feed chamber, acid chamber, and alkali chamber are separated by an ion exchange membrane, wherein: An anion exchange membrane is installed between the feed chamber and the acid chamber to allow anions in the electrodialysis solution to pass through and combine with protons generated by the bipolar membrane to form sulfuric acid. A cation exchange membrane is installed between the feed chamber and the alkali chamber to allow cations in the electrodialysis solution to pass through and combine with hydroxide ions generated by the bipolar membrane to form cobalt hydroxide.

[0017] The working principle of this invention, utilizing bipolar membrane electrodialysis technology to recover cobalt from waste heat batteries, is as follows: The bipolar membrane is an electrically driven composite membrane composed of a cation exchange layer (N-type membrane), an interfacial hydrophilic layer (catalytic layer), and an anion exchange layer (P-type membrane). Under the action of a DC electric field, the bipolar membrane dissociates water, yielding protons and hydroxide ions on both sides of the membrane. Combining the bipolar membrane with anion and cation exchange membranes constitutes a bipolar membrane electrodialysis system. Under suitable conditions, anions in the solution permeate through the anion exchange membrane and combine with protons generated by the bipolar membrane to form acids, while cations permeate through the cation exchange membrane and combine with hydroxide ions generated by the bipolar membrane to form bases.

[0018] After the reaction of the positive electrode material in the waste thermal battery, it mainly contains transition metal sulfides, oxides, and chlorides. In water, these react with hydrogen peroxide to produce metal sulfates, elemental sulfur, and chlorides. The electrode solution from the waste thermal battery dissociates in aqueous solution into sulfate, chloride, and cobalt, iron, lithium, and potassium ions. Under an electric field, cobalt, iron, lithium, and potassium ions combine with hydroxide ions generated by the bipolar membrane through a cation exchange membrane to form a mixture of cobalt hydroxide, iron hydroxide, lithium hydroxide, and potassium hydroxide. Nitrous acid and chloride ions combine with protons generated by the bipolar membrane through an anion exchange membrane to form a mixture of sulfuric acid and hydrochloric acid. Under appropriate conditions, sulfuric acid and cobalt hydroxide can be produced using a bipolar membrane electrodialysis unit.

[0019] The beneficial technical effects of this invention are as follows: 1. Filling the gap in cobalt recovery from waste thermal batteries This technology targets the recovery of cobalt from waste thermal batteries. As a special type of solid-state molten salt battery, waste thermal batteries cannot be treated using methods similar to those for other battery waste. This technology focuses on waste thermal batteries, providing a specialized recycling solution for this field and filling a gap in the recycling of this specific resource.

[0020] 2. Raw material-specific compatibility This technology targets the occurrence forms of cobalt (transition metal sulfides, oxides, etc.) in the positive electrode waste of waste heat batteries. It utilizes specific acid leaching ratios and electrodialysis parameters (such as current densities of 2–20 A / m³). 2 This solves the problem of poor adaptability of traditional methods to molten salt battery waste.

[0021] 3. The overall process is simple. This technology achieves selective separation of cobalt directly using bipolar membrane electrodialysis through a four-step process of "disassembly-dissolution-electrodialysis-concentration," eliminating the need for complex extraction or precipitation steps, thus shortening the process and reducing equipment investment. Operating conditions such as temperature and current density are well-defined and relatively easy to control.

[0022] Existing technologies involve many steps, such as acid leaching, impurity removal, selective co-extraction, deep impurity removal, bipolar membrane electrodialysis, and evaporation concentration. Each step has complex requirements for controlling conditions such as solution pH, temperature, and reagent dosage.

[0023] 4. High recovery rate A bipolar membrane electrodialysis device is used to dissociate water into protons and hydroxide ions using the membrane material. Under the action of an electric field, cobalt ions combine with hydroxide ions to form cobalt hydroxide, and sulfate ions combine with protons to form sulfuric acid. This achieves a one-step simultaneous recovery of cobalt and sulfuric acid. The total yield of the prepared cobalt hydroxide is 95.9% to 97.8%, which is high in yield and quality (rapidly preparing cobalt hydroxide with a purity of up to 95.2% to 96.2%). At the same time, sulfuric acid solution is obtained as a byproduct. The raw material utilization rate is high and the production cost is low.

[0024] 5. Improved environmental friendliness Using only sodium / potassium sulfate and sulfuric acid as raw materials, it is inexpensive, produces no organic reagent pollution, and reduces wastewater discharge. It achieves resource recycling and reduces environmental pollution.

[0025] 6. Low equipment requirements The bipolar membrane electrodialysis unit used in this invention is small in size, has high production efficiency, can operate continuously, is inexpensive, consumes less energy than traditional processes, and improves the utilization rate of raw materials, making it easy to scale up industrially. Detailed Implementation

[0026] The following detailed description illustrates the specific implementation method: Example 1: A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology, the operation is as follows: Disassembly of waste batteries: Disassemble the waste batteries and remove the positive electrode.

[0027] Positive electrode sheet processing: Take 1 kg of positive electrode sheet, add 10 L of purified water and 0.5 L of 50% sulfuric acid, stir at 30°C for 20 minutes, and then pass it through a microporous filter with a pore size of 10 micrometers to obtain electrodialysis solution.

[0028] Bipolar membrane electrodialysis treatment: The electrodialysis solution is pumped into the feed chamber of the bipolar membrane electrodialysis unit. Pure water is pumped into the acid and alkali chambers respectively. An 8% sodium sulfate solution is added to the electrode chamber. The bipolar membrane electrodialysis unit is started, and the current density is controlled at 13 A / m³. 2 The voltage is 45V; the temperature of the feed chamber, acid chamber, and alkali chamber is 35℃. When the conductivity of the feed chamber drops to 2000 μS / cm, the solutions in the feed chamber, alkali chamber, and acid chamber are collected. The alkali chamber solution is cobalt hydroxide solution, and the acid chamber solution is sulfuric acid solution.

[0029] Preparation of cobalt hydroxide concentrate: Pump the cobalt hydroxide solution into the reverse osmosis concentrator, control the gauge pressure to 0.6 MPa, and carry out reverse osmosis concentration until the mass percentage concentration of cobalt hydroxide in the concentrate is 16%. Stop the reverse osmosis and collect the reverse osmosis concentrate.

[0030] Using the method of Example 1, the detection data of cobalt hydroxide and sulfuric acid obtained from five preparations are shown in Table 1 below.

[0031] Table 1

[0032] Example 2: A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology, the operation is as follows: Disassembly of waste batteries: Disassemble the waste batteries and remove the positive electrode.

[0033] Positive electrode sheet processing: Take 1 kg of positive electrode sheet, add 15 L of purified water and 0.8 L of 50% sulfuric acid, stir at 40°C for 25 minutes, and then pass it through a microporous filter with a pore size of 8 micrometers to obtain electrodialysis solution.

[0034] Bipolar membrane electrodialysis treatment: The electrodialysis solution is pumped into the feed chamber of the bipolar membrane electrodialysis unit. Pure water is pumped into the acid and alkali chambers respectively. A 7% potassium sulfate solution is added to the electrode chamber. The bipolar membrane electrodialysis unit is started, and the current density is controlled at 18 A / m³. 2The voltage is 40V; the temperature of the feed chamber, acid chamber, and alkali chamber is 40℃. When the conductivity of the feed chamber drops to 2100 μS / cm, the solutions in the feed chamber, alkali chamber, and acid chamber are collected. The alkali chamber solution is cobalt hydroxide solution, and the acid chamber solution is sulfuric acid solution.

[0035] Preparation of cobalt hydroxide concentrate: Pump the cobalt hydroxide solution into the reverse osmosis concentrator, control the gauge pressure to 0.7 MPa, and carry out reverse osmosis concentration until the mass percentage concentration of cobalt hydroxide in the concentrate is 17%. Stop the reverse osmosis and collect the reverse osmosis concentrate.

[0036] Using the method of Example 2, the detection data of cobalt hydroxide and sulfuric acid obtained from five preparations are shown in Table 2 below.

[0037] Table 2

[0038] Example 3: A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology, the operation is as follows: Disassembly of waste batteries: Disassemble the waste batteries and remove the positive electrode.

[0039] Positive electrode sheet processing: Take 1 kg of positive electrode sheet, add 15 L of purified water and 0.8 L of 50% sulfuric acid, stir at 40°C for 25 minutes, and then pass it through a microporous filter with a pore size of 8 micrometers to obtain electrodialysis solution.

[0040] Bipolar membrane electrodialysis treatment: The electrodialysis solution is pumped into the feed chamber of the bipolar membrane electrodialysis unit. Pure water is pumped into the acid and alkali chambers respectively. A 5% potassium sulfate solution is added to the electrode chamber. The bipolar membrane electrodialysis unit is started, and the current density is controlled at 2 A / m³. 2 The voltage is 20V; the temperature of the feed chamber, acid chamber, and alkali chamber is 25℃. When the conductivity of the feed chamber drops to 1500 μS / cm, the solutions in the feed chamber, alkali chamber, and acid chamber are collected. The alkali chamber solution is cobalt hydroxide solution, and the acid chamber solution is sulfuric acid solution.

[0041] Preparation of cobalt hydroxide concentrate: Pump the cobalt hydroxide solution into the reverse osmosis concentrator, control the gauge pressure to 0.7 MPa, and carry out reverse osmosis concentration until the mass percentage concentration of cobalt hydroxide in the concentrate is 15%. Stop the reverse osmosis and collect the reverse osmosis concentrate.

[0042] Using the method of Example 3, the detection data of cobalt hydroxide and sulfuric acid obtained from five preparations are shown in Table 3 below.

[0043] Table 3

[0044] Example 4: A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology, the operation is as follows: Disassembly of waste batteries: Disassemble the waste batteries and remove the positive electrode.

[0045] Positive electrode sheet processing: Take 1 kg of positive electrode sheet, add 15 L of purified water and 0.8 L of 50% sulfuric acid, stir at 40℃ for 28 minutes, and then pass it through a microporous filter with a pore size of 8 micrometers to obtain electrodialysis solution.

[0046] Bipolar membrane electrodialysis treatment: The electrodialysis solution is pumped into the feed chamber of the bipolar membrane electrodialysis unit. Pure water is pumped into the acid and alkali chambers respectively. A 10% potassium sulfate solution is added to the electrode chamber. The bipolar membrane electrodialysis unit is started, and the current density is controlled at 20 A / m³. 2 The voltage is 50V; the temperature of the feed chamber, acid chamber, and alkali chamber is 50℃. When the conductivity of the feed chamber drops to 2800 μS / cm, the solutions in the feed chamber, alkali chamber, and acid chamber are collected. The alkali chamber solution is cobalt hydroxide solution, and the acid chamber solution is sulfuric acid solution.

[0047] Preparation of cobalt hydroxide concentrate: Pump the cobalt hydroxide solution into the reverse osmosis concentrator, control the gauge pressure to 0.8 MPa, and carry out reverse osmosis concentration until the mass percentage concentration of cobalt hydroxide in the concentrate is 15%. Stop the reverse osmosis and collect the reverse osmosis concentrate.

[0048] Using the method of Example 4, the detection data of cobalt hydroxide and sulfuric acid obtained from five preparations are shown in Table 4 below.

[0049] Table 4

Claims

1. A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology, characterized in that, Includes the following steps: S1. Disassembly of waste batteries: Disassemble the waste batteries and remove the positive electrode plates; S2. Positive electrode sheet treatment: Dissolve the positive electrode sheet in water and add sulfuric acid solution. Control the mass ratio of the positive electrode sheet to the volume of pure water and sulfuric acid to be 1:(9~19):(0.2~1) (kg / L). Stir at 20~50℃ for 10~30 minutes, and then filter through a 1~10 micrometer microporous filter to obtain electrodialysis solution. S3. Bipolar Membrane Electrodialysis Treatment: The electrodialysis solution is pumped into the feed chamber of the bipolar membrane electrodialysis unit, and pure water is pumped into the acid and alkali chambers respectively. A 5-10% sodium sulfate or potassium sulfate solution is added to the electrode chamber. After starting the equipment, the current density is controlled at 2-20 A / m. 2 The voltage is 20-50V, and the temperature of the liquid chamber, acid chamber, and alkali chamber is 25-50℃. When the conductivity of the liquid chamber drops to 1500-3000us / cm, the cobalt hydroxide solution in the alkali chamber and the sulfuric acid solution in the acid chamber are collected. S4. Concentration treatment: Pump the cobalt hydroxide solution into a reverse osmosis concentrator and concentrate it to a mass concentration of 15-18% under a gauge pressure of 0.5-0.8 MPa to obtain a cobalt hydroxide concentrate.

2. The method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology according to claim 1, characterized in that: In step S2, the mass ratio of the positive electrode sheet to the volume ratio of pure water and sulfuric acid is 1:15:0.8 (kg / L).

3. The method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology according to claim 2, characterized in that: The current density mentioned in step S3 is 18 A / m 2 The voltage is 40V.

4. A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology according to claim 3, characterized in that: In step S3, the temperature of the liquid / acid / alkali chamber is controlled at 40℃.

5. A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology according to claim 4, characterized in that: The concentration of the sulfuric acid solution is 50%.

6. A method for recovering cobalt from waste thermal batteries using bipolar membrane electrodialysis technology according to claim 5, characterized in that: The bipolar membrane of the bipolar membrane electrodialysis device is composed of a cation exchange layer, an interfacial hydrophilic layer, and an anion exchange layer.

7. A bipolar membrane electrodialysis system for recovering cobalt from waste thermal batteries, characterized in that, The device includes a bipolar membrane electrodialysis unit, which at least comprises a feed chamber, an acid chamber, an alkali chamber, and an electrode chamber, wherein: The feed chamber is used to contain the electrodialysis solution and is connected to an external pump to input the electrodialysis solution after the waste heat battery positive electrode sheet has been treated. The acid chamber and the alkali chamber are used to contain pure water, and each is connected to a pure water source. The polar chamber is used to contain a sodium sulfate or potassium sulfate solution of a certain concentration; The bipolar membrane electrodialysis device is equipped with a bipolar membrane, which is composed of a cation exchange layer, an interfacial hydrophilic layer and an anion exchange layer, and is used to dissociate water and separate ions under the action of an electric field.

8. The bipolar membrane electrodialysis system according to claim 7, characterized in that, The bipolar membrane electrodialysis unit also includes an electrode assembly that provides a voltage of 20–50V to maintain the temperature of the feed chamber, acid chamber, and alkali chamber at 25–50°C and generates 2–20A / m 2 The current density.

9. The bipolar membrane electrodialysis system according to claim 8, characterized in that, The feed chamber, acid chamber, and alkali chamber are separated by an ion exchange membrane, wherein: An anion exchange membrane is installed between the feed chamber and the acid chamber to allow anions in the electrodialysis solution to pass through and combine with protons generated by the bipolar membrane to form sulfuric acid. A cation exchange membrane is installed between the feed chamber and the alkali chamber to allow cations in the electrodialysis solution to pass through and combine with hydroxide ions generated by the bipolar membrane to form cobalt hydroxide.

Images