Patent Description:
Lithium-ion batteries have been widely used in various industries such as electronic products and electric vehicles; as a production amount and a usage amount of lithium-ion batteries increase significantly, in a few years, there will be a large quantity of lithium-ion batteries that need a waste recovery treatment. If the lithium-ion batteries are not treated properly, environmental pollution and resource waste may be caused; therefore, recovery of lithium-ion batteries is imminent and greatly significant, and is not only beneficial to being environmentally friendly, but also beneficial to resource recycling.

<CIT> discloses a method for removing iron and aluminum from a leaching solution (nickel-cobalt-manganese sulphate solution) generated in recovery of valuable metals from a waste lithium-ion battery. The method comprises the following steps of (<NUM>) adjusting the pH of the leaching solution to be <NUM>-<NUM>, and adding an oxidant to oxidize ferrous iron into ferric iron; (<NUM>) adjusting the pH of a system to be <NUM>-<NUM>, ageing and filtering to obtain filtrate and iron and aluminum slag; and (<NUM>) adjusting the pH of the system to be <NUM>-<NUM>, ageing and filtering to obtain a purified solution and aluminum slag, wherein the aluminum slag obtained in the step (<NUM>) is used for adjusting the pH of the system in the step (<NUM>) as a modifier.

Iron and aluminum are main impurities during the recovery of positive electrode materials from spent lithium-ion batteries, and both the removal and recovery of the impurities get extensive discussions and in-depth research from scholars. In a hydrometallurgical process of recovering spent batteries, a nickel-cobalt-manganese solution contains a large amount of iron and aluminum; and separating and recovering this part of iron and aluminum will be of a large significance. In hydrometallurgical processes of nickel-cobalt-manganese hydrometallurgy, the following procedures are widely used: acid leaching of raw materials, impurity removal, and extraction and separation; and in the impurity removal procedure, the most important work is to remove iron and aluminum impurities. In industry, a pH value is adjusted to <NUM>-<NUM> usually in a manner of adding sodium hydroxide or sodium carbonate, to precipitate iron in a solution in a form of sodium jarosite or ferric hydroxide, and to precipitate aluminum in a form of aluminum hydroxide. The generated slag is filtered and washed into an iron-aluminum slag that needs to be scrapped. Such an iron-aluminum slag has a very low economic value due to impure components thereof, contains a specific amount of nickel, cobalt, and manganese hydroxides, and is hazardous waste. An ordinary landfill treatment not only causes severe harm to the environment, but also causes loss of high-value nickel, cobalt, and manganese resources.

In view of this, an objective of embodiments of the present invention is to provide a method for recycling iron and aluminum from a nickel-cobalt-manganese solution as defined by appended claim <NUM>.

In the method according to the embodiments of the present invention, iron and aluminum can be effectively removed from a solution, and in addition, iron and aluminum are recycled, so that a resource recycling rate can be effectively increased, a process is appropriate, costs are relatively low, environmental pollution is low, and produced by-products can be returned to a hydrometallurgical system. In the process system of the present invention, no excess hazardous slag is discharged, leading to good economic and social benefits.

The objective of the present invention is achieved through the method of claim <NUM>.

According to an embodiment of the present invention, the battery powder may be obtained by crushing battery waste. According to an embodiment of the present invention, the battery waste may be selected from waste positive electrode materials obtained by disassembling spent lithium batteries or waste positive electrode materials produced during lithium battery manufacturing. In some embodiments, after leaching and copper removal are performed on the battery powder, a copper-removed solution containing nickel, cobalt, manganese, iron, and aluminum is obtained.

According to the present invention, the removing iron and aluminum by adjusting a pH value in stages includes:.

According to the present invention, the goethite slag is washed and dried to obtain a goethite product. In this embodiment of the present invention, the neutralizer includes, but is not limited to, one or more of sodium carbonate, potassium carbonate, calcium carbonate, calcium hydroxide, or magnesium hydroxide. In some embodiments, after the goethite slag is washed and dried, purity of the obtained goethite product reaches <NUM>% or higher.

According to some specific embodiments of the present invention, the pH value is controlled to <NUM>-<NUM>, a reaction temperature is <NUM>-<NUM>, a reaction time is <NUM>-<NUM>, the reaction is ended when the pH value is stable, and the goethite slag is obtained, thereby avoiding accumulation of an excess slag. In some specific embodiments of the present invention, the pH value is adjusted to <NUM>-<NUM>, a reaction temperature is <NUM>-<NUM>, a reaction time is <NUM>-<NUM>, and the iron-aluminum slag and the iron-removed solution are obtained.

According to an embodiment of the present invention, the method further includes: extracting the obtained iron-removed solution to obtain a nickel-cobalt-manganese product.

According to an embodiment of the present invention, the alkaline solution is a solution including at least one of sodium hydroxide or potassium hydroxide. Preferably, the alkaline solution is a solution having a concentration of <NUM>-<NUM>%. In some embodiments, the iron-aluminum slag and the alkaline solution are mixed at a caustic ratio of <NUM>-<NUM>. In some specific embodiments, the iron-aluminum slag and the alkaline solution are mixed, are heated to a temperature of <NUM>-<NUM>, and at a stirring speed of <NUM>-<NUM> r/min, are stirred and react for <NUM>-<NUM>.

A sodium metaaluminate solution is generated from the aluminum slag in the iron-aluminum slag in a manner of alkaline leaching, and nickel, cobalt, manganese, and iron in the iron-aluminum slag are concentrated and retained in the alkaline residue, so that the two parts are separated. In some embodiments, nickel, cobalt, manganese, and iron in the obtained aluminum-containing solution are less than <NUM>/L, and a content of nickel, cobalt, manganese, and iron in the obtained alkaline residue may reach approximately <NUM>%.

According to the present invention, after the aluminum-containing solution and the alkaline residue are obtained, the method further includes: returning the alkaline residue to the acid leaching procedure.

According to the present invention, the aluminum-containing solution is heated and stirred, and then, carbon dioxide is introduced, the pH value is controlled to <NUM>-<NUM>, the reaction is ended when the pH value is stable, and the aluminum hydroxide and the aluminum-removed solution are obtained.

According to an embodiment of the present invention, carbon dioxide is introduced, where a rate of introducing carbon dioxide is <NUM>-<NUM>/min.

In some embodiments, the aluminum-containing solution is heated and stirred at a stirring speed of <NUM>-<NUM> r/min and a reaction temperature of <NUM>-<NUM>. Aluminum hydroxide is prepared from the sodium metaaluminate solution through carbonation for recovery of aluminum therein. In some embodiments, purity of the obtained aluminum hydroxide may be <NUM>-<NUM>%. The aluminum-removed solution is rich in by-products such as sodium carbonate and sodium bicarbonate. The aluminum-removed solution may be used as a neutralizer and returned to the system for removing iron and aluminum in stages. According to an embodiment of the present invention, after the aluminum hydroxide and the aluminum-removed solution are obtained, the method further includes: using the aluminum-removed solution to adjust the pH value of the solution.

The method in the embodiments of the present invention has the following advantages and effects:
In the embodiments of the present invention, an iron-aluminum slag that is hazardous solid waste is creatively recycled, not only high-value nickel, cobalt, and manganese metals that are hazardous to the environment are recovered, but also high-quality goethite is produced, where purity of the obtained goethite product reaches <NUM>% or higher. In addition, aluminum therein is used for producing an aluminum hydroxide product having an economic value. The process of the embodiments of the present invention is simple and feasible, and nickel, cobalt, manganese, iron, and aluminum can be separated in one step, and therefore, are recycled separately. The aluminum-removed solution obtained in the process may be reused in the system as a neutralizer. In the process of the embodiments of the present invention, no liquid or solid waste is generated.

<FIG> is a flowchart of a method for recycling an aluminum slag from a nickel-cobalt-manganese solution according to an embodiment of the present invention.

The present invention is further described below in detail with reference to embodiments, but implementations of the present invention are not limited thereto.

Referring to <FIG>, specifically, a method for recycling an aluminum slag from a nickel-cobalt-manganese solution is provided, including the following steps:.

In this embodiment of the present invention, the spent battery powder, as a raw material, is acid-leached to obtain the nickel-cobalt-manganese solution containing copper, iron, and aluminum. Copper in the solution is recovered after being replaced by an iron powder, and then, a neutralizer is added to remove iron and aluminum from the solution, to obtain a qualified nickel-cobalt-manganese solution. However, iron and aluminum in the iron-aluminum slag generated in an impurity removal reaction have low grades, and cannot be directly recovered. Moreover, the iron-aluminum slag contains a specific amount of nickel, cobalt, and manganese that need to be separated from iron and aluminum for recovery. A sodium metaaluminate solution is generated from the aluminum slag in the iron-aluminum slag in a manner of alkaline leaching, and nickel, cobalt, manganese, and iron in the iron-aluminum slag are concentrated and retained in the alkaline residue, so that the two parts are separated. Aluminum hydroxide is prepared from the sodium metaaluminate solution through carbonation for recovery of aluminum therein. In addition, the aluminum-removed solution rich in by-products, such as sodium carbonate, is obtained. An alkaline residue rich in nickel, cobalt, manganese, and iron is returned to the process for recovery of nickel, cobalt, and manganese therein. In the alkaline residue treatment process in this embodiment of the present invention, an original hazardous iron-aluminum slag can be recycled into a usable aluminum hydroxide product, a sodium carbonate solution, and goethite having an economic value.

The present invention is further described below in detail with reference to embodiments to help a person skilled in the art to understand the present invention. It is necessary to specifically note that the embodiments are only used to further illustrate the present invention and cannot be understood as limitations to the protection scope of the present invention.

In addition, the raw materials that are mentioned below and that are not specified in detail are all commercially available products. Concentrations of metal ions in the following embodiments are all measured through atomic absorption spectroscopy (AAS) or inductively coupled plasma atomic emission spectroscopy (ICP-AES). A concentration of fluoride ion is measured through fluoride electrode potentiometry. The process steps or preparation methods not mentioned in detail are process steps or preparation methods known to a person skilled in the art.

This embodiment provided a method for recycling an aluminum slag from a nickel-cobalt-manganese solution including the following steps:.

(<NUM>) Lithium-ion battery waste was crushed and sieved to obtain a battery powder. (<NUM>) The battery powder was leached by using sulfuric acid to obtain a nickel-cobalt-manganese solution containing copper and aluminum, where a total concentration of nickel, cobalt and manganese was <NUM>/L, and a concentration of aluminum was <NUM>/L; an iron powder was added to the solution for copper removal to obtain a copper-removed solution, where a concentration of iron in the copper-removed solution was <NUM>/L; sodium carbonate was added to the copper-removed solution at <NUM> to control a pH value at the end of the reaction to <NUM>, and a goethite slag was obtained after the reaction was performed for <NUM>, and was washed and dried to obtain a goethite product having purity of <NUM>% and an iron content of <NUM>%; sodium carbonate was then added at <NUM> to adjust the pH value of the solution to <NUM>-<NUM>, to obtain an iron-aluminum slag and an iron-removed solution, where in the iron-aluminum slag, the iron content was <NUM>%, and an aluminum content was <NUM>%; and subsequent extraction was performed on the obtained iron-removed solution to obtain a nickel-cobalt-manganese product. The contents of nickel, cobalt, manganese, iron, and aluminum in goethite and the goethite-removed solution were shown in Table <NUM>. The contents of nickel, cobalt, manganese, iron, and aluminum in the iron-aluminum slag and the iron-removed solution were shown in Table <NUM>.

(<NUM>) <NUM>% sodium hydroxide solution was added to <NUM> of the obtained iron-aluminum slag at a caustic ratio of <NUM> for reaction at a constant temperature of <NUM> and a stirring speed of <NUM> r/min for <NUM>, and a slurry was filtered while it was hot after the reaction was ended, to obtain a sodium metaaluminate solution and an alkaline residue, where concentrations of nickel, cobalt, manganese, and iron in the sodium metaaluminate solution were respectively <NUM>/L, <NUM>/L, <NUM>/L, and <NUM>/L, and a concentration of aluminum was <NUM>/L; and a total content of nickel, cobalt, manganese, and iron in the alkaline residue was <NUM>%, and an aluminum content was <NUM>%. The contents of nickel, cobalt, and manganese in the sodium metaaluminate solution and the alkaline residue were shown in Table <NUM>.

(<NUM>) The alkaline residue obtained in step (<NUM>) was returned to the acid leaching procedure; carbon dioxide was introduced into the obtained sodium metaaluminate solution at a rate of <NUM>/min, where the reaction temperature was controlled to <NUM>, the stirring speed was controlled to <NUM> r/min, and the pH value at the end of the reaction was controlled to <NUM>, the slurry was filtered after the reaction was ended, where a filtrate was a sodium carbonate-containing solution, and an aluminum content was <NUM>/L, and the obtained sodium carbonate-containing solution was used as a neutralizer in step (<NUM>) for controlling or adjusting the pH value; and a filter residue was washed to obtain an aluminum hydroxide product, where purity of the aluminum hydroxide was measured to be <NUM>%. The contents of nickel, cobalt, and manganese in the sodium carbonate-containing solution and the filter residue were shown in Table <NUM>.

(<NUM>) Lithium-ion battery waste was crushed and sieved to obtain a battery powder. (<NUM>) The battery powder was leached by using sulfuric acid to obtain a nickel-cobalt-manganese solution containing copper and aluminum, where a total concentration of nickel, cobalt and manganese was <NUM>/L, and a concentration of aluminum was <NUM>/L; an iron powder was added to the solution for copper removal to obtain a copper-removed solution, where a concentration of iron in the copper-removed solution was <NUM>/L; calcium hydroxide was added to the copper-removed solution at <NUM> to control a pH value at the end of the reaction to <NUM>, and a goethite slag was obtained after the reaction was performed for <NUM>, and was washed and dried to obtain a goethite product having purity of <NUM>% and an iron content of <NUM>%; calcium hydroxide was then added at <NUM> to adjust the pH value of the solution to <NUM>-<NUM>, to obtain an iron-aluminum slag and an iron-removed solution, where in the iron-aluminum slag, the iron content was <NUM>%, and an aluminum content was <NUM>%; and subsequent extraction was performed on the iron-removed solution to obtain a nickel-cobalt-manganese product. The contents of nickel, cobalt, manganese, iron, and aluminum in goethite and the goethite-removed solution were shown in Table <NUM>. The contents of nickel, cobalt, manganese, iron, and aluminum in the iron-aluminum slag and the iron-removed solution were shown in Table <NUM>.

(<NUM>) The alkaline residue obtained in step (<NUM>) was returned to the acid leaching procedure; carbon dioxide was introduced into the obtained sodium metaaluminate solution at a rate of <NUM>/min, where the reaction temperature was controlled to <NUM>, the stirring speed was controlled to <NUM> r/min, and the pH value at the end of the reaction was controlled to <NUM>, the slurry was filtered after the reaction was ended, where a filtrate was a sodium carbonate-containing solution, and an aluminum content was <NUM>/L, and the obtained sodium carbonate-containing solution may be used as a neutralizer in step (<NUM>) for controlling or adjusting the pH value; and a filter residue was washed to obtain an aluminum hydroxide product, where purity of the aluminum hydroxide was measured to be <NUM>%. The contents of nickel, cobalt, and manganese in the sodium carbonate-containing solution and the filter residue were shown in Table <NUM>.

(<NUM>) Lithium-ion battery waste was crushed and sieved to obtain a battery powder. (<NUM>) The battery powder was leached by using sulfuric acid to obtain a nickel-cobalt-manganese solution containing copper and aluminum, where a total concentration of nickel, cobalt and manganese was <NUM>/L, and a concentration of aluminum was <NUM>/L; an iron powder was added to the solution for copper removal to obtain a copper-removed solution, where a concentration of iron in the copper-removed solution was <NUM>/L; sodium carbonate was added to the copper-removed solution at <NUM> to control a pH value at the end of the reaction to <NUM>, and a goethite slag was obtained after the reaction was performed for <NUM>, and was washed and dried to obtain a goethite product having purity of <NUM>% and an iron content of <NUM>%; sodium carbonate was then added at <NUM> to adjust the pH value of the solution to <NUM>-<NUM>, to obtain an iron-aluminum slag and an iron-removed solution, where in the iron-aluminum slag, the iron content was <NUM>%, and an aluminum content was <NUM>%; and subsequent extraction was performed on the iron-removed solution to obtain a nickel-cobalt-manganese product. The contents of nickel, cobalt, manganese, iron, and aluminum in goethite and the goethite-removed solution were shown in Table <NUM>. The contents of nickel, cobalt, manganese, iron, and aluminum in the iron-aluminum slag and the iron-removed solution were shown in Table <NUM>.

Claim 1:
A method for recycling iron and aluminum from a nickel-cobalt-manganese solution, comprising the following steps:
performing leaching and copper removal on a battery powder to obtain a copper-removed solution, and removing iron and aluminum by adjusting a pH value in stages to obtain a goethite slag and an iron-aluminum slag respectively, wherein the removing iron and aluminum by adjusting a pH value in stages comprises: adding a neutralizer, controlling the pH value to <NUM>-<NUM>, and heating for a reaction, to obtain the goethite slag; and adding a neutralizer, adjusting the pH value to <NUM>-<NUM>, and heating for a reaction, to obtain the iron-aluminum slag and an iron-removed solution; wherein the goethite slag is washed and dried to obtain a goethite product;
mixing the iron-aluminum slag with an alkaline solution, and heating and stirring, to obtain an aluminum-containing solution and an alkaline residue; and
heating and stirring the aluminum-containing solution, introducing carbon dioxide, and controlling the pH value to <NUM>-<NUM>, ending the reaction when the pH value is stable, to obtain aluminum hydroxide and an aluminum-removed solution;
wherein after the aluminum-containing solution and the alkaline residue are obtained, the method further comprises returning the alkaline residue to the acid leaching procedure; and the aluminum-removed solution is used as the neutralizer and returned to the system for removing iron and aluminum in stages,
wherein, the aluminum-containing solution is a sodium metaaluminate solution.