阅读说明：本技术 一种从废旧电池中回收石墨的方法 (Method for recovering graphite from waste batteries ) 是由 谭春波 于 2021-09-15 设计创作，主要内容包括：本发明公开了一种从废旧电池中回收石墨的方法,涉及电池回收技术领域,所述回收方法具体包括以下步骤：S1：预处理；S2：过筛；S3：热处理；S4：碱浸；S5：酸浸；S6：二次酸浸；S7：高温修复。本发明通过对含有正极、负极以及塑料隔膜的电极粉进行石墨回收,使得废旧电池回收体系更加完善,回收率高；本发明回收方法利用碱浸、多次酸浸使石墨的纯度达到98%以上,提高了回收石墨的纯度,且回收过程中通过高温对石墨进行修复,提升了石墨的性能,本发明回收工艺流程较少,操作简单,能耗低,降低了生产成本,且回收石墨纯度高,性能稳定,适宜广泛推广。(The invention discloses a method for recovering graphite from waste batteries, which relates to the technical field of battery recovery, and specifically comprises the following steps: s1: pre-treating; s2: sieving; s3: heat treatment; s4: alkaline leaching; s5: acid leaching; s6: secondary acid leaching; s7: and (5) high-temperature repairing. According to the invention, the graphite recovery is carried out on the electrode powder containing the anode, the cathode and the plastic diaphragm, so that the waste battery recovery system is more complete and the recovery rate is high; the recovery method of the invention utilizes alkaline leaching and multiple acid leaching to ensure that the purity of the graphite reaches more than 98 percent, improves the purity of the recovered graphite, repairs the graphite through high temperature in the recovery process, and improves the performance of the graphite.)

1. A method for recovering graphite from waste batteries is characterized by comprising the following steps: the recovery method specifically comprises the following steps:

s1: pretreatment: discharging, disassembling and crushing the recovered waste lithium iron phosphate battery to obtain lithium iron phosphate electrode waste;

s2: sieving: screening the mechanically crushed lithium iron phosphate electrode waste, and removing large aluminum foils, copper foils and diaphragm plastic paper to obtain electrode powder;

s3: and (3) heat treatment: carrying out heat treatment on the screened electrode powder under protective gas;

s4: alkaline leaching: and (3) performing pressure alkaline leaching on the electrode powder after heat treatment by using a NaOH solution with the concentration of 50g/L, wherein the liquid-solid ratio is 4-6: 1, obtaining alkaline leaching graphite after reaction, and washing to be neutral;

s5: acid leaching: and (3) carrying out acid treatment on the alkaline leaching graphite by using a sulfuric acid solution with the concentration of 18.4mol/L, wherein the liquid-solid ratio is 4-6: 1, adjusting the pH value to 0-1, and reacting to obtain acid-dipped graphite;

s6: secondary acid leaching: and (3) carrying out secondary acid leaching treatment on the acid-leached graphite by using a hydrochloric acid solution with the concentration of 12mol/L, wherein the liquid-solid ratio is 2-4: 1, adjusting the pH value to 0-1, filtering after reaction, washing to be neutral to obtain secondary acid-dipped graphite, wherein the filtrate can be recycled;

s7: high-temperature repair: and (3) regenerating and repairing the graphite by using the secondarily acid-leached graphite at high temperature under the protective gas, wherein the reaction temperature is 1500-1800 ℃, and obtaining a final graphite product.

2. The method for recovering graphite from waste batteries according to claim 1, wherein: the protective gas used in the heat treatment in the step S2 is any one of nitrogen or argon, the heat treatment temperature is 500-700 ℃, and the time is 2-4 hours.

3. The method for recovering graphite from waste batteries according to claim 1, wherein: the reaction temperature in the step S4 is 70-90 ℃, and the reaction time is 4-6 h.

4. The method for recovering graphite from waste batteries according to claim 1, wherein: the reaction temperature of the step S5 is 70-90 ℃, and the reaction time is 2-4 h.

5. The method for recovering graphite from waste batteries according to claim 1, wherein: the reaction time in the step S6 is 2-4 h.

6. The method for recovering graphite from waste batteries according to claim 1, wherein: and in the step S7, the high-temperature repairing protective gas is any one of nitrogen or argon, and the reaction time is 2-4 h.

Technical Field

The invention relates to the technical field of battery recovery, in particular to a method for recovering graphite from waste batteries.

Background

The waste lithium ion battery can cause certain harm to human health and ecological environment, and the recovery is an important way for realizing a closed loop system of returning battery materials to a value chain and is also the best choice for properly treating the waste lithium ion battery.

At present, the recovery method for recovering the waste lithium ion battery negative electrode graphite mainly comprises the following steps: (1) direct high-temperature graphitization: directly placing the recovered graphite slag in the protection of inert atmosphere at the high temperature of 1400 ℃ and 3200 ℃ for purification treatment; (2) putting the recovered graphite slag into inorganic acid and an oxidant for metal impurity removal, then putting the graphite slag into phenolic resin or asphalt for coating, and then putting the graphite slag into a high-temperature inert atmosphere with the temperature of more than 900 ℃ for regeneration and repair; (3) and (3) carrying out simple acid washing and impurity removal on the negative pole piece containing the graphite to obtain the recovered graphite. By adopting the methods (1) and (2), the battery-grade graphite cathode material with higher capacity and higher first charge-discharge efficiency can be generally obtained, but the energy consumption is higher; and compared with the graphite sold in the market, the recycled graphite obtained in the similar method (3) has lower specific capacity and first charge-discharge efficiency, and the recycling effect is not ideal.

The prior patents such as Chinese patent publication numbers are: CN101710632, entitled "method for recovering and repairing graphite as anode material of waste lithium ion battery", which comprises soaking the recovered negative plate in water to separate copper foil from graphite, then removing impurities by inorganic acid at room temperature, high-temperature treating, surface modifying and solidifying, carbonizing the surface modifying agent at 900 ℃ in nitrogen atmosphere to obtain the repaired graphite product. The method is used for recycling the graphite in the lithium ion battery.

Most lithium batteries in the market at present are recycled only aiming at complete negative pole pieces, and the whole scrapped full battery powder containing positive and negative poles, diaphragms and current collectors is less in design, the recycling system is incomplete, and the recycling rate is low. Accordingly, those skilled in the art have provided a method for recovering graphite from waste batteries to solve the problems set forth in the background art as described above.

Disclosure of Invention

The invention aims to provide a method for recovering graphite from waste batteries so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a method for recovering graphite from waste batteries specifically comprises the following steps:

s1: pretreatment: discharging, disassembling and crushing the recovered waste lithium iron phosphate battery to obtain lithium iron phosphate electrode waste;

s2: sieving: screening the mechanically crushed lithium iron phosphate electrode waste, and removing large aluminum foils, copper foils and diaphragm plastic paper to obtain electrode powder;

s3: and (3) heat treatment: carrying out heat treatment on the screened electrode powder under protective gas;

s4: alkaline leaching: and (3) performing pressure alkaline leaching on the electrode powder after heat treatment by using a NaOH solution with the concentration of 50g/L, wherein the liquid-solid ratio is 4-6: 1, obtaining alkaline leaching graphite after reaction, and washing to be neutral;

s5: acid leaching: and (3) carrying out acid treatment on the alkaline leaching graphite by using a sulfuric acid solution with the concentration of 18.4mol/L, wherein the liquid-solid ratio is 4-6: 1, adjusting the pH value to 0-1, and reacting to obtain acid-dipped graphite;

s6: secondary acid leaching: and (3) carrying out secondary acid leaching treatment on the acid-leached graphite by using a hydrochloric acid solution with the concentration of 12mol/L, wherein the liquid-solid ratio is 2-4: 1, adjusting the pH value to 0-1, filtering after reaction, washing to be neutral to obtain secondary acid-dipped graphite, wherein the filtrate can be recycled;

s7: high-temperature repair: and (3) regenerating and repairing the graphite by using the secondarily acid-leached graphite at high temperature under the protective gas, wherein the reaction temperature is 1500-1800 ℃, and obtaining a final graphite product.

As a further scheme of the invention: the protective gas used in the heat treatment in the step S2 is any one of nitrogen or argon, the heat treatment temperature is 500-700 ℃, and the time is 2-4 hours.

As a still further scheme of the invention: the reaction temperature in the step S4 is 70-90 ℃, and the reaction time is 4-6 h.

As a still further scheme of the invention: the reaction temperature of the step S5 is 70-90 ℃, and the reaction time is 2-4 h.

As a still further scheme of the invention: the reaction time in the step S6 is 2-4 h.

As a still further scheme of the invention: and in the step S7, the high-temperature repairing protective gas is any one of nitrogen or argon, and the reaction time is 2-4 h.

Compared with the prior art, the invention has the beneficial effects that: the invention discloses a method for recovering graphite from waste batteries, which is characterized in that the graphite is recovered from electrode powder containing a positive electrode, a negative electrode and a plastic diaphragm, so that a waste battery recovery system is more perfect and the recovery rate is high; the recovery method of the invention utilizes alkaline leaching and multiple acid leaching to ensure that the purity of the graphite reaches more than 98 percent, improves the purity of the recovered graphite, repairs the graphite through high temperature in the recovery process, and improves the performance of the graphite.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the embodiment of the present invention, the first and second substrates,

example 1

A method for recovering graphite from waste batteries specifically comprises the following steps:

s1: pretreatment: discharging, disassembling and crushing the recovered waste lithium iron phosphate battery to obtain lithium iron phosphate electrode waste;

s2: sieving: screening the mechanically crushed lithium iron phosphate electrode waste, and removing large aluminum foils, copper foils and diaphragm plastic paper to obtain electrode powder;

s3: and (3) heat treatment: carrying out heat treatment on the screened electrode powder under protective gas;

s4: alkaline leaching: and (3) performing pressure alkaline leaching on the electrode powder after heat treatment by using a NaOH solution with the concentration of 50g/L, wherein the liquid-solid ratio is 4: 1, obtaining alkaline leaching graphite after reaction, and washing to be neutral;

s5: acid leaching: and (3) carrying out acid treatment on the alkaline leaching graphite by using a sulfuric acid solution with the concentration of 18.4mol/L, wherein the liquid-solid ratio is 4: 1, adjusting the pH value to be 0, and reacting to obtain acid-dipped graphite;

s6: secondary acid leaching: and (3) carrying out secondary acid leaching treatment on the acid-leached graphite by using a hydrochloric acid solution with the concentration of 12mol/L, wherein the liquid-solid ratio is 2: 1, adjusting the pH value to 0, filtering after reaction, washing to be neutral to obtain secondary acid-dipped graphite, wherein the filtrate can be recycled;

s7: high-temperature repair: and (3) regenerating and repairing the graphite subjected to secondary acid leaching at high temperature under the protection gas, wherein the reaction temperature is 1500 ℃, and obtaining a final graphite product.

Further, the protective gas used in the heat treatment in step S2 is nitrogen, the heat treatment temperature is 500 ℃, and the time is 2 hours.

Still further, the reaction temperature in step S4 was 70 ℃, and the reaction time was 4 hours.

Still further, the reaction temperature of step S5 was 70 ℃, and the reaction time was 2 hours.

Still further, the reaction time in step S6 was 2 h.

Still further, the protective gas for high-temperature repair in step S7 is nitrogen, and the reaction time is 2 hours.

Example 2

A method for recovering graphite from waste batteries specifically comprises the following steps:

s1: pretreatment: discharging, disassembling and crushing the recovered waste lithium iron phosphate battery to obtain lithium iron phosphate electrode waste;

s2: sieving: screening the mechanically crushed lithium iron phosphate electrode waste, and removing large aluminum foils, copper foils and diaphragm plastic paper to obtain electrode powder;

s3: and (3) heat treatment: carrying out heat treatment on the screened electrode powder under protective gas;

s4: alkaline leaching: and (3) performing pressure alkaline leaching on the electrode powder after heat treatment by using a NaOH solution with the concentration of 50g/L, wherein the liquid-solid ratio is 6: 1, obtaining alkaline leaching graphite after reaction, and washing to be neutral;

s5: acid leaching: and (3) carrying out acid treatment on the alkaline leaching graphite by using a sulfuric acid solution with the concentration of 18.4mol/L, wherein the liquid-solid ratio is 6: 1, regulating the pH value to be 1, and reacting to obtain acid-dipped graphite;

s6: secondary acid leaching: and (3) carrying out secondary acid leaching treatment on the acid-leached graphite by using a hydrochloric acid solution with the concentration of 12mol/L, wherein the liquid-solid ratio is 4: 1, regulating the pH value to 1, filtering after reaction, washing to be neutral to obtain secondary acid-dipped graphite, wherein the filtrate can be recycled;

s7: high-temperature repair: and (3) regenerating and repairing the graphite by using the secondarily acid-leached graphite at a high temperature of 1800 ℃ under the protection gas to obtain a final graphite product.

Further, in step S2, the protective gas used for the heat treatment is argon, the heat treatment temperature is 700 ℃, and the time is 4 hours.

Still further, the reaction temperature in step S4 was 90 ℃, and the reaction time was 6 h.

Still further, the reaction temperature of step S5 was 90 ℃, and the reaction time was 4 hours.

Still further, the reaction time in step S6 was 4 h.

Further, in step S7, the protective gas for high temperature repair is argon, and the reaction time is 4 hours.

Example 3

A method for recovering graphite from waste batteries specifically comprises the following steps:

s1: pretreatment: discharging, disassembling and crushing the recovered waste lithium iron phosphate battery to obtain lithium iron phosphate electrode waste;

s2: sieving: screening the mechanically crushed lithium iron phosphate electrode waste, and removing large aluminum foils, copper foils and diaphragm plastic paper to obtain electrode powder;

s3: and (3) heat treatment: carrying out heat treatment on the screened electrode powder under protective gas;

s4: alkaline leaching: and (3) performing pressure alkaline leaching on the electrode powder after heat treatment by using a NaOH solution with the concentration of 50g/L, wherein the liquid-solid ratio is 5: 1, obtaining alkaline leaching graphite after reaction, and washing to be neutral;

s5: acid leaching: and (3) carrying out acid treatment on the alkaline leaching graphite by using a sulfuric acid solution with the concentration of 18.4mol/L, wherein the liquid-solid ratio is 5: 1, adjusting the pH value to 0.5, and reacting to obtain acid-dipped graphite;

s6: secondary acid leaching: and (3) carrying out secondary acid leaching treatment on the acid-leached graphite by using a hydrochloric acid solution with the concentration of 12mol/L, wherein the liquid-solid ratio is 3: 1, adjusting the pH value to 0.5, filtering after reaction, washing to be neutral to obtain secondary acid-dipped graphite, wherein the filtrate can be recycled;

s7: high-temperature repair: and (3) regenerating and repairing the graphite at high temperature under the protection gas by using the graphite subjected to secondary acid leaching, wherein the reaction temperature is 1650 ℃, and thus obtaining the final graphite product.

Further, the protective gas used in the heat treatment in step S2 is nitrogen, the heat treatment temperature is 600 ℃, and the time is 3 hours.

Still further, the reaction temperature in step S4 was 80 ℃, and the reaction time was 5 hours.

Still further, the reaction temperature of step S5 was 80 ℃, and the reaction time was 3 hours.

Still further, the reaction time in step S6 was 3 h.

Further, the protective gas for high-temperature repair in step S7 is nitrogen, and the reaction time is 3 hours.

Examples of the experiments

The graphite products recovered in example 1, example 2 and example 3 were subjected to graphite purity examination.

Experimental methods

Putting the graphite product recovered in the example 1 in a drying oven at 105 ℃ to be dried to a constant weight, weighing 1g of graphite into a double-covered ceramic crucible, putting the double-covered ceramic crucible with the sample in a muffle furnace at 950 ℃, taking out the double-covered ceramic crucible after timing for 7 minutes by using a stopwatch, cooling to room temperature, weighing, reducing 0.005g, and calculating the volatile component to be 0.5%; weighing 1g of graphite into a graphite boat, putting the graphite boat with the sample into a muffle furnace at 950 ℃, keeping the temperature for 90 minutes, taking out the graphite boat, putting the graphite boat in a dryer, cooling the graphite boat to room temperature, weighing the graphite boat, reducing the weight by 0.986g, and calculating the ash content to be 1.4% and the graphite purity to be =100% and the volatile component to be ash content to be = 98.1%.

Putting the graphite product recovered in the example 2 in a drying oven at 105 ℃ to be dried to a constant weight, weighing 1g of graphite into a double-covered ceramic crucible, putting the double-covered ceramic crucible with the sample in a muffle furnace at 950 ℃, taking out the double-covered ceramic crucible after counting for 7 minutes by using a stopwatch, cooling to room temperature, weighing, reducing 0.004g, and calculating the volatile component to be 0.4%; weighing 1g of graphite into a graphite boat, putting the graphite boat with the sample into a muffle furnace at 950 ℃, keeping the temperature for 90 minutes, taking out the graphite boat, putting the graphite boat in a dryer, cooling the graphite boat to room temperature, weighing the graphite boat, reducing the weight by 0.988g, and calculating the ash content to be 1.2% and the graphite purity to be =100% and the volatile component to be ash content to be = 98.4%.

Putting the graphite product recovered in the example 3 in a drying oven at 105 ℃ to be dried to a constant weight, weighing 1g of graphite into a double-covered ceramic crucible, putting the double-covered ceramic crucible with the sample in a muffle furnace at 950 ℃, taking out the double-covered ceramic crucible after timing for 7 minutes by using a stopwatch, cooling to room temperature, weighing, reducing 0.005g, and calculating the volatile component to be 0.5%; weighing 1g of graphite into a graphite boat, putting the graphite boat with the sample into a muffle furnace at 950 ℃, keeping the temperature for 90 minutes, taking out the graphite boat, putting the graphite boat in a dryer, cooling the graphite boat to room temperature, weighing the graphite boat, reducing the weight by 0.987g, and calculating the ash content to be 1.3% and the graphite purity to be =100% and the volatile component to be ash content to be = 98.2%.

From the experimental results, the purity of the graphite recovered in examples 1, 2 and 3 was more than 98%, and it can be seen that the purity of the graphite recovered by the present recovery method was more than 98%, which was higher than the purity of the graphite recovered by the conventional recovery method.

In conclusion, the method has the advantages that the graphite recovery is carried out on the electrode powder containing the anode, the cathode and the plastic diaphragm, so that the waste battery recovery system is more complete and the recovery rate is high; the recovery method of the invention utilizes alkaline leaching and multiple acid leaching to ensure that the purity of the graphite reaches more than 98 percent, improves the purity of the recovered graphite, repairs the graphite through high temperature in the recovery process, and improves the performance of the graphite.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.