阅读说明：本技术 一种废旧电池正极原料的回收方法 (Method for recovering anode raw material of waste battery ) 是由 衣淑立 陈大林 刘世和 刘爱春 柴艮风 李芬霞 陈兴纲 马婷 于 2021-08-25 设计创作，主要内容包括：一种废旧电池正极原料的回收方法,该方法包括以下步骤：步骤一：将废旧电池放电、拆解,焙烧、剥离破碎,分离出废旧磷酸铁锂电池正极粉料；步骤二：将磷酸铁锂正极粉料加水浆化后加硫酸进行浸出,浸出完成后固液分离,得到浸出液和浸出渣；步骤三：浸出液加碱液调节pH值,加入铁粉置换除铜,得除杂后溶液；步骤四：除杂后溶液根据含铁和磷的比例补加磷酸钠,磷酸铁锂浸出除杂后液和碱液、氧化剂双氧水等氧化按一定的比例同时加入,同过程调节溶液pH值至1.5-3.5沉淀磷酸铁,固液分离后得到磷酸铁沉淀；步骤五：滤液为含锂的溶液,该滤液通入二氧化碳,即得沉淀锂。本发明简单高效,易于批量工业化生产。(A method for recovering a positive electrode raw material of a waste battery comprises the following steps: the method comprises the following steps: discharging, disassembling, roasting, stripping and crushing the waste lithium iron phosphate battery, and separating out the positive electrode powder of the waste lithium iron phosphate battery; step two: adding water into lithium iron phosphate anode powder for slurrying, adding sulfuric acid for leaching, and performing solid-liquid separation after leaching to obtain leachate and leaching residues; step three: adding alkali liquor into the leachate to adjust the pH value, adding iron powder to replace and remove copper, and obtaining solution after impurity removal; step four: adding sodium phosphate into the solution after impurity removal according to the proportion of iron and phosphorus, simultaneously adding the solution after impurity removal of lithium iron phosphate leaching, alkali liquor, oxidant hydrogen peroxide and the like according to a certain proportion, adjusting the pH value of the solution to 1.5-3.5 in the same process to precipitate the iron phosphate, and performing solid-liquid separation to obtain an iron phosphate precipitate; step five: the filtrate is lithium-containing solution, and carbon dioxide is introduced into the filtrate to obtain the precipitated lithium. The method is simple and efficient, and is easy for batch industrial production.)

1. A method for recovering a positive raw material of a waste battery is characterized by comprising the following steps:

the method comprises the following steps: discharging, disassembling, roasting, stripping and crushing the waste lithium iron phosphate battery, and separating out the positive electrode powder of the waste lithium iron phosphate battery;

step two: adding water into lithium iron phosphate anode powder, pulping, preheating, adding sulfuric acid for leaching, and performing solid-liquid separation after leaching to obtain a leaching solution and leaching residues;

step three: adding alkali liquor into the leachate to adjust the pH value to 1.5-2.5, adding iron powder to replace and remove copper, continuously adding alkali liquor to adjust the pH value to 3.3-3.5, removing aluminum, and performing solid-liquid separation to obtain a solution after impurity removal;

step four: adding sodium phosphate into the solution after impurity removal according to the proportion of iron and phosphorus, adding pure water or the solution after iron precipitation into a reaction container as a base solution, heating, stirring and impurity removal, spraying the solution by using spraying equipment, adding alkali liquor and an oxidant, adding the solution after lithium iron phosphate leaching and impurity removal, the alkali liquor, the oxidant, hydrogen peroxide and the like into the solution simultaneously according to a certain proportion, adjusting the pH value of the solution to 1.5-3.5 in the same process, precipitating iron phosphate, and performing solid-liquid separation to obtain an iron phosphate precipitate;

step five: the filtrate is lithium-containing solution, the pH value of the solution is adjusted to 10.0-11.5, evaporation concentration and solid-liquid separation are carried out, and carbon dioxide is introduced into the filtrate to precipitate lithium.

2. The method for recovering the positive electrode raw material of the waste battery as claimed in claim 1, wherein: in the step one, the waste batteries are waste lithium iron phosphate batteries, and the waste lithium iron phosphate batteries refer to waste battery packs or waste single batteries.

3. The method for recovering the positive electrode raw material of the waste battery as claimed in claim 1, wherein: in the first step, the temperature of the anode powder material leaching process is 50-80 ℃, and the leaching time is 3-4 h.

4. The method for recovering the positive electrode raw material of the waste battery as claimed in claim 1, wherein: the alkali liquor is a sodium hydroxide solution with the concentration of 100-200 g/L.

5. The method for recovering the positive electrode raw material of the waste battery as claimed in claim 1, wherein: and (3) adding alkali liquor into the leachate in the third step to adjust the pH value to 2.0, adding iron powder to replace and remove copper, and continuously adding alkali liquor to adjust the pH value to 3.4.

6. The method for recovering the positive electrode raw material of the waste battery as claimed in claim 1, wherein: and step four, adjusting the pH value of the solution to 2.5 to precipitate the ferric phosphate.

7. The method for recovering the positive electrode raw material of the waste battery as claimed in claim 1, wherein: and step five, adjusting the pH value of the solution to 11.

Technical Field

The invention relates to the technical field of waste battery recovery, in particular to a method for recovering a positive electrode raw material of a waste battery.

Background

At present, the recovery of waste lithium iron phosphate power batteries is mainly based on a wet process, and the pretreated waste lithium iron phosphate active material is dissolved by an acid leaching method, then impurity elements such as aluminum and copper are removed by purification, and finally metal elements in a leaching solution are recovered. Aluminum ions are used as impurity elements in sulfuric acid leaching solution, and when metal elements are subsequently recovered in the form of iron phosphate and lithium carbonate precursors, the electrochemical performance of the sulfuric acid leaching solution is affected due to the introduction of the impurity elements.

Most of the recovery processing methods of the waste lithium iron phosphate batteries are in the laboratory research stage, and some methods are difficult to realize, high in cost and complex in process during real industrialization; and the pyrogenic process has large energy consumption, large equipment investment and low recycling economy. Therefore, under the condition that the lithium iron phosphate battery is used for the mature electric vehicle, effective recovery of the waste lithium iron phosphate battery by using a method which is low in cost, easy to realize industrialization, simple in operation and feasible in process is urgently needed to be found.

Disclosure of Invention

The invention aims to solve the technical problem of providing a simple and efficient method for recovering the anode raw material of the waste battery, which is easy for industrial production.

In order to solve the problems, the invention discloses a method for recovering a waste battery anode raw material, which is characterized by comprising the following steps of:

the method comprises the following steps: discharging, disassembling, roasting, stripping and crushing the waste lithium iron phosphate battery, and separating out the positive electrode powder of the waste lithium iron phosphate battery;

step two: adding water into lithium iron phosphate anode powder, pulping, preheating, adding sulfuric acid for leaching, and performing solid-liquid separation after leaching to obtain a leaching solution and leaching residues;

step three: adding alkali liquor into the leachate to adjust the pH value to 1.5-2.5, adding iron powder to replace and remove copper, continuously adding alkali liquor to adjust the pH value to 3.3-3.5, removing aluminum, and performing solid-liquid separation to obtain a solution after impurity removal;

step four: adding sodium phosphate into the solution after impurity removal according to the proportion of iron and phosphorus, adding pure water or the solution after iron precipitation into a reaction container as a base solution, heating, stirring and impurity removal, spraying the solution by using spraying equipment, adding alkali liquor and an oxidant, adding the solution after lithium iron phosphate leaching and impurity removal, the alkali liquor, the oxidant, hydrogen peroxide and the like into the solution simultaneously according to a certain proportion, adjusting the pH value of the solution to 1.5-3.5 in the same process, precipitating iron phosphate, and performing solid-liquid separation to obtain an iron phosphate precipitate;

step five: the filtrate is lithium-containing solution, the pH value of the solution is adjusted to 10.0-11.5, evaporation concentration and solid-liquid separation are carried out, and carbon dioxide is introduced into the filtrate to precipitate lithium.

The waste battery is a waste lithium iron phosphate battery, and the waste lithium iron phosphate battery refers to a waste battery pack or a waste single battery.

In the first step, the temperature of the anode powder material leaching process is 50-80 ℃, and the leaching time is 3-4 h.

The alkali liquor is a sodium hydroxide solution with the concentration of 100-200 g/L.

And (3) adding alkali liquor into the leachate in the third step to adjust the pH value to 2.0, adding iron powder to replace and remove copper, and continuously adding alkali liquor to adjust the pH value to 3.4.

And step four, adjusting the pH value of the solution to 2.5 to precipitate the ferric phosphate.

And step five, adjusting the pH value of the solution to 11.

Compared with the prior art, the invention has the following advantages:

1. according to the invention, the waste lithium iron phosphate battery is disassembled, crushed and separated to obtain the anode powder which is high in purity and contains a small amount of copper and aluminum, the anode powder is leached only by using sulfuric acid in the leaching process, and hydrogen peroxide is not added in the leaching process for oxidation. The purpose is to avoid that a large amount of bubbles are generated by adding hydrogen peroxide in the leaching process, so that powder floats and overflows to influence the leaching effect; secondly, the iron concentration of the leachate is high, if iron is oxidized into ferric iron, iron phosphate precipitation can be generated by adjusting the pH value to be more than 1.5 during impurity removal, and even ferric hydroxide precipitation can be generated possibly, so that impurity removal cannot be realized; and the PH value of the ferrous phosphate and hydroxide precipitate is higher, so that the impurity removal of the leachate can be simply realized, and the ferric phosphate is oxidized and precipitated after the impurity removal.

2. According to the invention, iron powder is added into the acid-leached lithium iron phosphate anode powder solution to replace and remove copper, and excessive iron powder is added, so that the copper removal depth in the solution is improved, and high-concentration ferrous iron in the solution is not oxidized. Meanwhile, the pH value of the aluminum removal is not too high so as to avoid the generation of ferrous phosphate or aluminum phosphate.

3. The solution after ferric phosphate precipitation mainly contains sodium and lithium, but possibly other impurities, the pH value of the solution is adjusted, impurity precipitation is generated through filtration, the sodium sulfate is evaporated and concentrated to crystallize, the lithium ion concentration is improved, the impurity concentration is concentrated, lithium precipitation is performed after filtration, and the impurity content of the obtained lithium carbonate is greatly reduced.

Detailed Description

A method for recovering a positive electrode raw material of a waste battery comprises the following steps:

the method comprises the following steps: discharging, disassembling, roasting, stripping and crushing the waste lithium iron phosphate battery, and separating out the positive electrode powder of the waste lithium iron phosphate battery;

step two: adding water into lithium iron phosphate anode powder, pulping, preheating, adding sulfuric acid for leaching, and performing solid-liquid separation after leaching to obtain a leaching solution and leaching residues;

step three: adding alkali liquor into the leachate to adjust the pH value to 1.5-2.5, adding iron powder to replace and remove copper, continuously adding alkali liquor to adjust the pH value to 3.3-3.5, removing aluminum, and performing solid-liquid separation to obtain a solution after impurity removal;

step four: adding sodium phosphate into the solution after impurity removal according to the proportion of iron and phosphorus, adding pure water or the solution after iron precipitation into a reaction container as a base solution, heating, stirring and impurity removal, spraying the solution by using spraying equipment, adding alkali liquor and an oxidant, adding the solution after lithium iron phosphate leaching and impurity removal, the alkali liquor, the oxidant, hydrogen peroxide and the like into the solution simultaneously according to a certain proportion, adjusting the pH value of the solution to 1.5-3.5 in the same process, precipitating iron phosphate, and performing solid-liquid separation to obtain an iron phosphate precipitate;

step five: the filtrate is lithium-containing solution, the pH value of the solution is adjusted to 10.0-11.5, evaporation concentration and solid-liquid separation are carried out, and carbon dioxide is introduced into the filtrate to precipitate lithium. The waste lithium iron phosphate anode powder is leached only by adding acid, no oxidant is added, a large amount of bubbles are generated when hydrogen peroxide is added in the leaching section, and leached ferrous iron is oxidized into ferric iron in the leaching process, so that subsequent impurity removal is difficult. Only acid is added during leaching, the leaching of lithium, iron and phosphorus in the lithium iron phosphate can be ensured, and the impurity removal effect can be ensured because the PH value of phosphate and hydroxide precipitation of ferrous iron is higher. Wherein: the anode powder of the waste lithium iron phosphate battery is obtained by discharging, disassembling, stripping, crushing and separating the waste lithium iron phosphate battery. The battery anode powder material also contains a certain amount of aluminum powder and copper powder after being crushed. The waste lithium iron phosphate battery refers to a waste battery pack or a waste single battery. The manner of peeling and crushing refers to a manual method or a mechanical method. The waste lithium iron phosphate battery anode powder can also be waste lithium iron phosphate battery anode powder produced in the synthesis process of an anode material and the production process of batteries.

Iron powder is added to the solution of ferrous iron to displace copper and a slight excess of iron powder inhibits the oxidation of ferrous iron to ferric iron precipitation in the solution. Adjusting the pH value of the solution to 3.3-3.5, and aging for a sufficient time to remove the aluminum content below the required amount. The liquid-solid ratio is improved as much as possible in the leaching process, and copper and aluminum in the solution after impurity removal can be reduced to below 0.005 g/L. The ferric phosphate is synthesized by adding the solution after leaching and impurity removal of the lithium iron phosphate, alkali liquor and oxidant hydrogen peroxide into the base solution in parallel flow, so that the generated ferric phosphate has uniform granularity and high product quality. Wherein: the acid solution is a sulfuric acid solution with the volume concentration of 10-50%. The mass of the hydrogen peroxide is 0.55-0.6 times of the iron content in the solution after impurity removal.

Lithium is recovered by a traditional precipitation method, the pH value of the solution after iron precipitation is adjusted to 10.0-11.5 for impurity removal, evaporation and concentration are carried out until the concentration of lithium in the solution is 12-15 g/L, and impurity ions in the solution can also be precipitated. Because the sodium content in the lithium solution is high, carbon dioxide is introduced to precipitate lithium after the solution is concentrated, and sodium carbonate is not used to precipitate lithium, so that sodium sulfate crystallization caused by too high sodium concentration in the solution is avoided. Collecting a certain amount of waste lithium iron phosphate batteries, discharging, disassembling, and mechanically crushing and separating to obtain the positive powder of the waste lithium iron phosphate batteries, wherein the material contains a small amount of copper and aluminum. This material was used as the starting material in the following examples. Preparing 200g/L of alkali liquor for later use.

The waste battery is a waste lithium iron phosphate battery, and the waste lithium iron phosphate battery refers to a waste battery pack or a waste single battery. In the first step, the temperature of the anode powder material leaching process is 50-80 ℃, and the leaching time is 3-4 h. The alkali liquor is a sodium hydroxide solution with the concentration of 100-200 g/L. And (3) adding alkali liquor into the leachate in the third step to adjust the pH value to 2.0, adding iron powder to replace and remove copper, and continuously adding alkali liquor to adjust the pH value to 3.4. And step four, adjusting the pH value of the solution to 2.5 to precipitate the ferric phosphate. And step five, adjusting the pH value of the solution to 11.