Recovery of high value metals from lithium-ion batteries

Abstract

The invention there is provides a method for the selective recovery of metals from, LiBs, scrap, ore or electronics waste. The method includes the steps of leaching three or more metals selected from lithium, nickel, manganese and cobalt with a concentrated chloride salt solution, passing the metal containing leachate through an anion exchange resin to separate nickel with a dilute chloride solution followed by manganese and then cobalt, and selective precipitation and / or antisolvent precipitation to recover the respective metals as metal salts.

Description

[0001] Title: Recovery of High Value Metals from Lithium-Ion Batteries

[0002] Technical field of the invention

[0003] This invention relates to the selective recovery of cobalt, lithium, nickel and Manganese from Lithium-Ion Batteries (LiB) and other similar scrap or waste material.

[0004] Background to the invention

[0005] LiB demand has increased with advancement in technical applications such as electric vehicles, cell phones, laptops and many more rechargeable devices. The increasing demand for LiBs requires a method of recycling in order to recover the components.

[0006] The main components of LiBs are the cathode, anode, separator and electrolyte. The composition of the cathodes can be varied to obtain different battery properties affecting the efficiency. The lithium nickel manganese cobalt oxide (LiNiMnCo02) is the most commonly used.

[0007] The metal components of the cathodes include lithium, cobalt, nickel and manganese. Recycling of the spent LiBs is necessary to reduce the ecological footprint of their production and use and to provide a recycled source of the valuable metals.

[0008] The main components of LiBs are the cathode, anode, separator and electrolyte. Lithium hexafluorophosphate (LiPF6) is a common salt solution used in LiB electrolytes. LiPF6can form hydrofluoric (HF) acid in the presence of water. HF is highly corrosive.

[0009] It is an object of the invention to provide a method for the selective recovery of cobalt, lithium, nickel and manganese from LiBs. It is a further object to convert the highly corrosive HF to a less toxic fluoride. General description of the invention

[0010] According to the invention there is provided a method or process for the selective recovery of metals from, LiBs, scrap, ore or electronics waste, which method includes the steps of: leaching three or more metals selected from lithium, nickel, manganese and cobalt with a concentrated chloride salt solution; passing the metal containing leachate through an anion exchange resin to separate nickel with a dilute chloride solution followed by manganese and then cobalt; and selective precipitation and / or antisolvent precipitation to recover the respective metals as metal salts.

[0011] Known processes may be used for the crushing and separation of the cathode components from LiBs. LiB cathode components are preferred.

[0012] The leaching step may be conducted while decreasing the pH of the salt solution over time. The chloride concentration is about 6 to 9M, preferably about 8M.

[0013] Cobalt, Manganese and nickel are leached into solution as chloride complexes using concentrated chloride solutions, which could be calcium chloride, lithium chloride, magnesium chloride, aluminium chloride, ammonium chloride or hydrochloric acid or a mixture of these. The leaching extracts the cathode components in the form of chloride complexes which can be selectively loaded onto a strong base anion (SBA) resin or anion exchange resins (example Lewatit MonoPlus M500).

[0014] The acidity in the chloride solution is able to dissolve the lithium cobalt nickel manganese oxide into chloride complexes of the different metals into the leachate. The expected complexes when nickel, cobalt and manganese react with excess chlorides are shown below:

[0015] Nickel forms the tetrachloronickelate(ll)ion, [NiCU]2-, a tetrahedral anionic complex with the chloride ion ligand. )(green) + 6H2O(D

[0016] In the presence of an acid, a blue tetrachlorocobaltate (II) complex ion is formed when Co2+reacts with the chloride ion ligand.

[0017] [Co(H20)e] (aq) + 4CI (aq) [C0CI4] (aq)(blue) + 6H2O(|)

[0018] An anionic octahedral manganese (IV) chloro complex ion is produced when manganese (IV) oxide is introduced to concentrated chloride solution.

[0019] MnO2(S) + 4H+(aq) + 6CI (aq) — [MnCh]2(aq) + 2H2O(i)

[0020] Chloride leaching has a number of advantages for hydrometallurgical processing, including greater metal solubility, improved redox behaviour, and faster leaching rates. Chloride leaching uses fewer resources and is environmentally friendly. The spent chloride solution is preferably recycled to effect a zero liquid effluent process.

[0021] The method includes the use of a concentrated chloride salt solution to increase the chloride concentration for chloride complex formation. The advantage of using a chloride salt instead of high HCI acid is avoiding the hazardous high partial pressure of HCI at ambient and higher temperatures.

[0022] The pH of the solution is then decreased with mineral and / or organic acids to complete the leaching step.

[0023] Concentrated chloride solutions and hydrochloric and citric acids form anionic complexes and these can be removed with an anion exchange resin. A strong base anion (SBA) resin may be used in the chloride form to recover cobalt and nickel from the leachate. Selective elution of the components can be achieved with a number of solutions including alcohols, ketones and mixtures of these with water. Elution with an alcohol-water solution converts the anionic complexes to the cationic form which is desorbed from the anion resin allowing the different metals to be separated. The chloride complex of cobalt is selectively held onto anion resins selected from styrenic acrylic, and containing quaternary, tertiary, secondary or primary amine functional groups. The chloride complexes can be selectively eluted from the resin using a series of dilute chloride salt solutions, demineralized water and organic solvents. High purity cobalt can be produced using ion exchange to separate the cobalt from the other cathode components.

[0024] The formation of anionic complexes during leaching enables the use of SBA resin. A standard SBA resin is commonly used in water treatment and has a relatively low cost compared to specialised chelating resins. The SBA resin may be monodispersed, gel type with a quaternary amine type I functional group.

[0025] The metals are eluted by passing through a dilute aqueous chloride solution, which breaks the chloride complexes to form cationic ions. The eluate contains chromatographic fractions, which are sequentially treated to remove the different metals of interest. The first part contains mainly the nickel, which is then recovered by using a chelating resin (example Lewatit MDS TP220). The chelating resin is eluted with a strong mineral acid (example sulphuric acid). The eluate goes to further processing by neutralization and is obtained as a precipitate that is filtered, dried, and sold as such.

[0026] The nickel free eluate contains cobalt and manganese, with the manganese appearing first. The manganese stream is neutralized to form manganese hydroxide precipitate, which is filtered out.

[0027] The final fraction contains the cobalt, and this is neutralized with a carbonate salt (typically soda ash) to produce cobalt carbonate. The cobalt carbonate can be filtered out and dried and sold as such. The first part of the barren leach, or eluate, contains the excess acid, aluminium and the lithium, and this is returned to the leach to treat the next batch of black mass. Chloride and acidity are made up by adding CaCh and HCL This results in a build up of Al and Li in the leach circuit, but these have no negative effect on the leaching rate. These metals are recovered from a bleed of the leach, or by batch processing.

[0028] The nature of ion exchange is that it is scalable. Very small volumes are used in laboratory chromatographic separations (ml quantities). Small quantities are used in household appliances such as water filters and dishwashers as softeners. Industrial units operate from 5 liters to 20 0001. Mining applications may use millions of liters in hydrometallurgical processing plants.

[0029] The possibility of small scale means that modular plants can be built. The major advantage is that these are decentralized, minimizing the transport of batteries, shredded battery material and black mass. All are considered hazardous, and transport costs are high if not prohibited outright. Transport and border crossing costs were identified as the major contributing cost to LiB recycling.

[0030] The concentrated solid products can be transported at lower cost, as the weight is lower, and the hazards diminished. Cobalt in the black mass is in the trivalent form, which is significantly more toxic as compared to the divalent form of the product.

[0031] Sulphates and nitrates of the transition metals are less soluble in organic solvents than in water. They can be crystallised from aqueous solutions by the addition of sufficient amounts of solvent. The ratio of solvent to water is selected to selectively precipitate the metal salts. The anionic complexes will form precipitates on the addition of a base. This allows for selective precipitation by the controlling the pH. The precipitates and crystals are recovered by filtration. The chloride complex of cobalt is selectively precipitated by the addition of a base which may be alkali metal hydroxides, alkali earth hydroxides, ammonia and carbonates of the aforementioned bases. The above bases may also be used in conjunction with weak base anion resins in a stirred tank reactor.

[0032] Known processes may be used for the shredding of the batteries after dismantling and this invention can also be used to detoxify this shredded material. Calcium chloride can be used to detoxify the electrolyte by preventing the formation of HF in the presence of water. LiPF6forms HF when it reacts with water. Calcium chloride will form the insoluble salt calcium fluoride when it reacts with HF. The reaction sequence is shown below.

[0033] Reaction of LiPF6with water:

[0034] LiPF6+H2O 2HF + LiF + POF3

[0035] Reaction of HF with CaCI2: LiPF6:

[0036] 2HF + CaCI2CaF2+ 2HCI

[0037] The calcium chloride is also able to discharge the batteries as it has a high conductivity. The reaction however is slow and the heat produced does not represent a hazard in the presence of sufficient solution to act as a heat sink.

[0038] Detailed description of the invention

[0039] The invention is now described by way of example with reference to the accompanying flow diagram Figure 1 .

[0040] Known processes are used for the shredding of the LiB batteries after dismantling.

[0041] The method for the selective recovery of metals from, LiBs, includes the step of leaching lithium, nickel, manganese and cobalt with a concentrated chloride salt and hydrochloric acid solution. The metal containing leachate is then passed through an anion exchange resin, Lewatit MonoPlus M500™ in this example, to separate nickel with a dilute chloride solution followed by manganese and then cobalt. Finally selective precipitation is employed to recover the respective metals as metal salts.

[0042] Process Mass Balance

[0043] Typical Black Mass:

[0044] Leaching requires a 30% excess of acid.

[0045] Taking equivalent masses into account

[0046] The required acid in a leach batch is 19.51 x 1.3 = 25.4 moles of HCI per kg of Black Mass. Commercial HCI is about 11 M, therefore 25.4 / 11 = 2.3 litres of 32% HCI are required per kg of Black Mass.

[0047] The chloride concentration is made up to 8M using 9kg of Calcium Chloride, and water 60% by mass is required. The leach solution is therefore 9 x 2.5kg = 24.4kg 8M CaCI2+ 2.3 litres HCI

[0048] The density of 8M CaCI2is 1.4kg / l, so the total volume required is 17.4 + 2.3 = 19.7 litres of leach solution per kg of black mass.

[0049] The resin has an operating capacity of 40g / l total metals, but has almost no affinity for lithium, aluminium and calcium.

[0050] The total of Ni, Co, Mn and Cu is 16.5g per litre of Pregnant Leach Solution (PLS), therefore after 2.4 bed volumes of solution have passed through the resin bed, nickel will break through into the ion exchange effluent termed the Barren Leach Solution (BLS). The resin volume required to treat 1 kg of black mass leachate is 19.7 / 2.4 = 8.1 litres. The hydrogen ion can enter the pore volume of the resin by Acid Retardation. The pore volume is 25% of the BV.

[0051] The BLS is returned to the leach to treat further batches of black mass after nickel removal through the bis-picolylamine functionalised resin. Note that the aluminium and lithium concentrations increase with each recycle, but this does not affect the leach rate.

[0052] The ion exchange resin is eluted with a solution containing a lower concentration of chloride ions. If the concentration of chloride drops below 8, all the nickel and some of the manganese will be removed from the resin, as the anionic chloro-complexes of nickel break down. The nickel becomes a cationic aquo complex and is rejected by the resin as it now has the same charge as the functional groups of the resin.

[0053] The nickel chloride stream is then passed through a bis-picolylamine functionalised resin (example Lewatit TP220) which can selectively remove Nickel, allowing the other cations, mainly calcium and lithium to pass through the resin bed. This stream is then returned to the leach. As it has a lower chloride concentration, this is made up to 8M with calcium chloride.

[0054] At a chloride concentration of 6M, the manganese is rejected in the same way and is eluted. This stream is essentially free of free acidity and is neutralised with a base to form a manganese hydroxide precipitate, which is filtered off. The filtrate can be then returned to the leach.

[0055] At a chloride concentration of 4M chloride the cobalt is eluted by the same mechanism described for manganese and nickel. The cobalt is recovered as a carbonate precipitate which is filtered off, and dried. This is a saleable product, which can also be calcined to produce an oxide (C03O4).

[0056] The final elution is done with water and this will remove all the remaining metals from the anion resin. Water alone could be used for elution but this will not achieve as effective elution as the echelon elution described above.

[0057] Reverse osmosis membranes are used to maintain the chloride concentration and hydraulic balance.

[0058] Advantages of the claimed process includes:

[0059] 1 . Zero Liquid Discharge

[0060] 2. Ambient Temperature Operation

[0061] 3. Low-Cost Materials of Construction

[0062] 4. Scalable and modular

[0063] 5. Low Cost and Non-Hazardous Reagents

[0064] 6. Separation of the Cathode Metals

[0065] It shall be understood that the examples are provided for illustrating the invention further and to assist a person skilled in the art with understanding the invention and are not meant to be construed as unduly limiting the reasonable scope of the invention.

Claims

Claims1 . A method for the selective recovery of metals from, LiBs, scrap, ore or electronics waste, which method includes the steps of: leaching three or more metals selected from lithium, nickel, manganese and cobalt with a concentrated chloride salt solution; passing the metal containing leachate through an anion exchange resin to separate nickel with a dilute chloride solution followed by manganese and then cobalt; and selective precipitation and / or antisolvent precipitation to recover the respective metals as metal salts.

2. The method as claimed in claim 1 , wherein the leaching step is conducted while decreasing the pH of the salt solution over time and the chloride concentration is between 6 and 9M.

3. The method as claimed in claim 1 or claim 2, wherein Cobalt, Manganese and nickel are leached into solution as chloride complexes using concentrated chloride solutions in the form of chloride complexes which can be selectively loaded onto a strong base anion (SBA) resin or anion exchange resins (example Lewatit MonoPlus M500).

4. The method as claimed in any one of claims 1 to 3, effecting elution with an alcohol-water solution to convert the anionic complexes to the cationic form, which is desorbed from the anion resin allowing the different metals to be separated.

5. The method as claimed in any one of claims 1 to 3, effecting elution nby passing through a dilute aqueous chloride solution to form cationic ions, which are sequentially treated to remove the different metals of interest.

6. The method as claimed in claim 5, wherein a first part contains mainly the nickel, which is then recovered by using a chelating resin.

7. The method as claimed in claim 6, wherein the chelating resin is eluted with a strong mineral acid followed by neutralization and precipitation and filtration.

8. The method as claimed in claim 6, wherein a nickel free eluate contains cobalt and manganese, with the manganese appearing first and wherein the manganese stream is neutralized to form manganese hydroxide precipitate, which is filtered out.

9. The method as claimed in claim 8, wherein a final fraction contains the cobalt, which is neutralized with a carbonate salt to produce cobalt carbonate, which is filtered out.

10. The method as claimed in any one of claims 1 to 9, wherein barren leach or eluate is returned to the leach to treat the next batch of LiBs, scrap, ore or electronics waste.

11. A method substantially as described herein with reference to the accompanying flow diagram.