ZA200607874B

ZA200607874B - Method for the mixed recycling of lithium-based anode batteries and cells

Info

Publication number: ZA200607874B
Application number: ZA200607874A
Authority: ZA
Inventors: Farouk Tedjar; Jean-Claude Foudraz
Original assignee: Recupyl
Priority date: 2004-04-06
Filing date: 2006-09-20
Publication date: 2008-03-26
Also published as: DE602005001937D1; BRPI0509647A; FR2868603B1; ES2292140T3; AU2005234188A1; AU2005234188B2; WO2005101564A9; ATE369633T1; HK1101524A1; CA2559928A1; WO2005101564A1; CA2559928C; DK1733451T3; CN100527522C; US7820317B2; EP1733451B1; EP1733451A1; JP5128272B2; JP2007531977A; US20070196725A1

Abstract

The invention relates to a method for treating all types of lithium anode cells and batteries by means of a hydrometallurgical process at room temperature. The treatment method enables cells and batteries comprising a metallic lithium-based anode or an anode containing lithium incorporated in an anodic insertion compound to be treated under safe conditions, thus enabling the metallic casings, electrode contacts, cathode metal oxides and lithium salts to be separated and recovered.

Description

' : VES EEE SE

E 1

Me=thod for the mixed recycling of lithium-based a node batteries and cells.

Ba ckground of the invention

The invention relates to a meth-od for hydrometallurgical t reatment of cells and batteries comprising at least a lithium-based anode, a salt dissolved in an ele ctrolyte and a cathode comgorising at least one metal or a combination of me-tals selected from cobalt, nickel, manganese and iro n, for recovering the rec=overable fractions.

State of the art

The= increase in portable electroric products has resulted ir an expansion of the cells market (30 billion dollars i n 1998) with an annual growth of 6 % and the aut-onomy requirements via soumrces having a good energy density have doped the portable batteries market which presents an even greater growth (12 %). In particular, lithium systems have made considerable progresss over the last few years (plus 45 % in 3 years).

At the present time, batteries called ion lithium batteries arad polymer electrolyte batteries are the major technol ogical innovation of the last fifty years in the eleactrochemical generator field. However, despite the numerous advantages related to performances, lithium =systems continue to constitute a large source of pro ducts having a recognized «environmental impact. Th € effects are mainly related to the following compone nts: > heavy metals such as cathodic materials, » conducting salts with a fluoriane, arsenic or sulfonated compound base > organic solvents and » avery reactive alkaline meta_l.

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Many of thesse elements are not degradable a.nd often present a high deg ree of toxicity eithe-r directly as regards the health of human beings and anim als or indirectly by polluting the soil, water, plants ard food chain. Even dissemilinated in waste, theay contribute to polluting larger m atrices or to accentuating aRready problematic situations in the case of incineration with household waste.

Moreover, dispersing metals in waste is in contradiction with preservat ion of natural resources. Furthermore, some of the metals used in lithium systems are difficult and expensive to extract.

The state of the art shows a large number of attempts to make proposals for treating lithitem systems. Thus, the Patent US6511639 describes a metheod for recovering rmegative electrodes by means of a thermal treatment andl only concerns lith ium ion batteries. In the document WO-A-0223651, the trea_tment associates a cryogenic step followed by an incineration step and only cormcerns vanadium ox ide-based polymer lithium batteries.

The method described in French Patent application FR-A-2812973 propooses wet crushing of lithium ion batteries and nicke I metal hydride batteries wh ereas the method described in the document JP-A-11185833 proposes a somlution based on a thermal treatment and only comcerns lithium ion batteries . The method acco rding to the Patent application WO-A-9934473 proposes extraction using acetonitrile and only concerns lithium ion batteries.

The method =ccording to the Patent US 5882811 proposes cutting with a water jet followed by electrolysis in molten LiCl medium and distillation omf the electrolyte. It only concerns lithium ion batteries as does the method according to the Pate nt application JP-A-10330855 which proposes direct theermal treatment in & rotary furnace.

The method according to the Patent application JP 0287864 proooses extraction by solvent and only relates to lith ium ion batteries. The me®hods according to the Patent applications JP 1006266, JP 10158751 and JP-A-

102074539 propose a thermal tre atment comprised between 350°C and 1000°C ard only concern lithium ion batteries.

Or the other hand, the only methods industrially implemesnted in the world are two in number: 1 — The method called TOXCQO proposed in the Patent US 5888463 and preesented by W J. McLaughlin, Lithium battery recycling Froceedings of the 5th

International Seminar on Battery Waste Management (Florida 1993). It is applied in the United States for recycling batteries and cel Is made of lithium in a mi xture (LISO,, LiISOCI,, LiMnO,, LiFeS,, Li-ion and LiCF=,). The batteries and ce-lis are frozen in liquid nitrogen at -196°C before being crushed. The hosmogenates are recovered in an alkaline solution t© neutralize the acid co mpounds emitted (H,, SO,, SQC,,...) and to hydrolyze the organic solvents.

Tne lithium salts formed (Li,SO,, LiCl) are separated fron the residual metallic armd plastic fragments by a screening operation. Adding so dium carbonate to the so lutions enables the lithium to be precipitated in caarbonate form before purification and recrystallization of a technical quality salt. No indication is given on recovery of the cathodic metals. 2 — The SONY-SUMITOMO method presented during the 5" International

Se=minar on used battery and cel | management (Florida U SA, October 1998). It is «applied in Japan only on Li-ion batteries. The method iss based on calcination at a temperature of about 1000° C in a furnace. After calacination, the residues are crushed and screened. The screened powder contai ns cobalt oxides and other oxides. No lithium recycling indication is given.

In ageneral manner, it can be ob served from the state of time art that: - Thermal methods give rise to large problems of gas emi:ssions in particular of grezenhouse effect gases and are in contradiction with thes commitments of the staates that signed the recent inter national agreements. - Vet channel crushing processes give rise to large safety problems as regards thes hydrogen emitted when the batteries are crushed. Thiss problem also arises

E 4 ae in relation with an=y method proposing a mixture of lithium batteries and aqueous system. - The use of acetonitrile gives rise to large safesty problems in particulexr for the operating personmel and for emissions in the na tural environment.

And finally, two major handicaps are ascertained among all the oroposed methods: 1- Among 11 proposed methods, only one method is designed tom treat all types of lithium baatteries, 2- Two meth. ods out of the 11 are used industrially to date.

Lastly, in non-the rmal methods, no precise amd safe solution is propeosed for management of opoening of the batteries. : 15 Object of the Inv ention

The object of the invention is to provide a treatment method enatoling the shortcomings of tine prior art to be remedied amd, more particularly, providing a framework for pe=rforming recycling of lithium systems without any pollution transfer with a maximum recovery ensuring conversion of the resource into added-value compounds.

According to the invention, this object is achieved by the appendecd claims.

More particularly, this object is achieved by the fact that the method comprises dry crushing at ro om temperature in an inert at mosphere, treatment byw at least magnetic separati on and densimetric table foll owed by aqueous hydr olysis to recover at least the lithium in carbonate or lithhiophosphate form, an anion of said electrolyte salt and a concentrate compri sing at least one meta | of said cathode.

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Brief description of the drawings

Other advantages and features will become more cle=arly apparent from the folloxwing description of particula r embodiments of the finvention given as nor- restr ictive examples only and represented in the accompanying drawings, En whic h:

Figume 1 represents the X-ray diffraction spectr um of the hydrate=d lithio phosphate with a half a water molecule obt=ined by a particular embeodiment of a treatment method according to the inve=ntion.

Figumre 2 represents the X-ray diffraction spectrum of thee fine fraction obtaine=d by a particular embodiment of a teeatment method according to the invention.

Figures 3 and 4 schematically represent the differen—t steps of a treatmert methmod according to the inventior of a cell and/or a batteary comprising a lithiun- base - anode.

Figur-es 5 and 6 represent the NMR spectra using 188 M Hz scanning for fluoriree 19 amd 81 MHz scanning for phosphorus 31 of a phase= containing the PFg io n and =obtained by a particular em bodiment of a treatmert method according to the imvention.

Description of particular embodiments

To o-vercome the different shortcomings set out above , the present inventio n relatees to a method for treating all lithium systems separately or mixed. T-o perfo-rm recycling of batteries for beneficiation purposes... it is important to ope n the ssystem by crushing the batteries to access the recyclable fractions.

Howeaver, a lot of batteries to be recycled still have a strong charge and crushing them produces sparks and large inflammations or even explosions im particular with SO, or SOCI, sy"stems. To avoid these two drawbacks, two compolementary solutions are impl emented in the present invention.

Crushing is made safe by means of inert gases in very economical rmanner by placing the crushi ng system in an enclosure wit h a controlled atmos.-phere and pressure and by u sing suitable crushing systems .

In a first embodirment of the invention, the criushing operation is performed beforehand by sh redding by means of a rotary- shearing machine wwith a low speed of rotation preferably less than 11 revolutions per minute (rpm) . This step is designed to relesase the internal stresses of tke batteries. In a seccond step, the shredded cha_rge is crushed in a rotor system rotating at a mean speed preferably lower than 90 rpm.

In a second emboadiment of the present invention, the two crushing sy=stems are placed in a tightly sealed enclosure made inert b-y means of a gas that is either argon, or carbon dioxide, or a suitable mixture of the two gases. Exarmnination of the densities of tthe gases show that argon andl carbon dioxide will provide a good protection at=ove the crushed charge. [Gm [oe

These two gases vill expel the oxygen and nitrog en and provide a gass covering above the mill blades and above the crushed batteries. In addition, the presence of carbon dioxide will result in initiatirhg passivation of thee metallic lithium by formatio n of lithium carbonate at the surface, which slows down the reactivity of this metal.

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In the case of a mixture of these two gases, the proportion vari es from 10 % to 90 % of argon and from 90 % to 10 % of carbon dioxide, but t=he proportion of argon im the mixture is advantageously comprised between 10 7 and 35 %.

Gas infection is controlled by the residual oxygen content ancd by the internal pressure. These two parameters are advantageously set at: 1- an oxygen content comprised between 100 and 10000 pprm but preferably close to 5000 ppm, 2- a differential pressure comprised between 30 and 13 0 millibars but prefera bly close to 80 millibars.

Injectio n of inert gas is preferably only performed if one of the two parameters exceed s the setpoint values which enables the setpoint value of the consunptions to be considerably reduiced.

The cruashed charge is then sent to a vibrating screen with a mesh size smaller than or equal to 3 mm and equipped wvith a high-induction magnetic separator at the end of its output and with a demsimetric table. This operation enables 4 fraction sto be obtained in a single rum: 1- the u ndersized fine fraction which iss rich in metal oxides and czarbon, 2- the rmnagnetic fraction which is composed of stainless steel from the casings of the ceells and batteries, 3- the lense non-magnetic fraction which is composed of norm-ferrous metals and 4- the ron-magnetic fraction with a Bow density and which is composed of a mixture of paper and plastic.

Only thea undersized fine charge, obtained at 1 and composed - of metal oxides and cawmbon, has to be subjected to subsequent treatment. This treatment begins Eoy screening at 500 micrometers which enables an und-ersized fraction rich in cobalt and poor in copper (<0.3%) to be obtained. This ¢ harge can then be a m aterial treated by any recycling method of metal oxidess, in particular

E 8 those having a base comprising cobalt, nicke | and manganese or any mixture of these three metals.

In a particular e mbodiment of the present inwention, the undersize-d fine charge that passes the screening is suspended in hesavily stirred water. Thais turbulence in the bath enables the metal and lithium oxides to be released. Mixing the lithium hydroxide in solution will alkalize the s olution up to a pH of rnore than 12.

Hydrolysis of the crushed charge leads to thes formation of hydrogesn. However, management of the addition rate of the charges in the leaching reactor and creation of a very strong turbulence aloove the bath prevent risks of inflammation of the hydrogen and of explosion. This operation i s associated with making the atmosphere above the bath poorer in oxygen. This air comes from the suction of the mill casing and enables an oxygen-poor atmosphere to be maintained s.© as to permanently be at a concentration of less t han 0.5 % in volume, which is situated in the safety rancme of hydrogen. At thee end of the hydrolysis reacti on and after filtration, an alkaline solution of lithiuran salts and a suspension of m etal oxides and of carbon are obtained.

The solution is tkhen treated so as to separates the dissolved lithium whereas the insoluble charge is treated to recover the cathodic metals. Rec«overy of the dissolved lithiunn is performed from a solution having a pH Close to 12.

Acidification by means of a suitable reactamt enables the lithiurm salt to be precipitated.

In a particular application of the present inve ntion, the lithium is precipitated in the form of carb onate and the gases output from the mill are use-d as carbon dioxide input as precipitation reactant. This particular embodirment of the invention is advantageously applicable in the case of recycling of a mixture of cells and batteries including thionyl chloricde systems. This aedvantage is obtained by mea ns of the different solubility o#f the three gases in w-ater at room temperature and at ambient pressure.

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Solubility at 20°C

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Precipitation is performed by adjusting the pH from its initial value close to 13 to a value of 9. The precipitated product is washed by carbo n dioxide-saturated water then dried at 105°C. ©n account of the solubility of L.i,CO,, the residual lithium concentration remains high, about 1.8 g/l, and requires subsequent treatment.

In another application mode, the leaching solution having a pH of 12.1 and containing 11 g/l of lithium is neutralized by means of phosphoric acid at 85 % to a pH of less than 8.5. The solution is then realkalized up to a pH of more than 12. The precipitate formed is then separated by filtration. T he residual lithium concentration is 89 mg/l meaning that an extraction ratio of amore than 99.15 % is achieved. This residual li thium concentration is a limit «<oncentration as it corresponds to the solubility of Li;PO, which is 400 mg/l (Hand Book of

Chemistry and Physics, D.L.. Lide editor, 75th edition, 1293, monograph of chemistry and physics).

The precipitated solid is drieed and then analyzed by X-ray diffraction and by chemical analysis. The Li;PO, content is 93 % and analysis by X-ray diffraction shows that the product is a hydrated lithiophosphate with a 1/2 water molecule and therefore a water contemit of 7 %. This strongly confirms the purity of the product obtained as shown by the X-ray diffraction spectrum presented in figure 1.

The washed charge is treated differently depending on its composition. As thionyl chloride cells have very little influence on the contribution of cathodic rmaterials, the different ch arges will be differentia ted according to the rmnanganese/cobalt ratio.

T hree cases are encountered during treatment of mixed lithium cells and beatteries.

Mixture of cells and Relative concentration of cathodic

CASE Primary lithium mixed with High >95 <4 Low <5 %

N°1 a small proportion of

Lithium ion

CASE Primary lithium nixed with Between 40 and Between 60 and

CASE Lithium ion alone Low <2 Y= High >98 %

Ei hl Nl

Im case N°1, on account of its manganese compossition, the fine charge ceomposed of oxides and cartoon is usable in all the mesthods described in the state of the art and in particular in the two methods respexctively described in the

Patent applications FR-A-2704098 and EP-A-0620607 and in the Patent a pplications FR-A-2827710 ard WO-A-03021708.

Im case N° 2, the charge is dissolved in a 2N sulphuric medium at 80°C in the pwesence of steel shot in an ir on/cathodic mass ratio of ©.15. The pulp obtaimed is: cooled down to 60°C and then filtered. The solid pa:rt contains the carEoon whereas the solution, which is at a pH of less than 3, con tains zinc sulphate =and manganese as well as other metallic impurities, in particuslar copper. The cop=per is cemented by means of steel shot. After cementation, «divided metallic cop-per ard a solution with a pH comporised between 2 and 2.85 are obtained. This pH is raised to a value of 3.85 by means of soda at 20 %. T his modification of the

E 11 pH results in precipitation of the iron in thes form of hydroxides. Thais purified solution is ther neutralized at pH 5.8 and the=n subjected to electrolysi=s to obtain metallic cobalt in a traditional single-compamtment electrolysis config uration. In particular, a porevious treatment of the Apgpoplicant on zinc and naanganese sulphate solut ions as described in the Pate=nt applications FR-A-2827710 and

WO-A-030217 08 can advantageously be used.

In the case of the present invention, electrol ysis is performed at a te mperature of 55°C in a current density comprised betwveen 400 and 600A/m? oy using a stainless steel cathode and an antimony-l=ad alloy anode. The nmmanganese precipitates im oxyhydroxide form and in dioxide form. After filtr ation and leaching, it is sent to the recycling channels known in the state of the art and in particular those already mentioned for case N°1. The solution, which becomes poorer in cobalt and manganese, is richer ir acid which is re-used at process input.

In case N°3, the charge is mixed in solution and then purified in the same way as for case N°22. The solution resulting from ourification is then oxidizead to a pH comprised between 2.3 and 2.8 by means of" sodium hypochlorite to recipitate the cobalt hydroxide (lll).

At the end of the treatment of cases 2 and 3, the solution contains a part of lithium salts re sulting from reduction of the c=obaltite or inserted in the MnO, of the primary elements. This solution is neutra lized by means of soda at a pH of 8.5 to recover all the metals still remaining im the solution, and is theen sent to the leaching water treatment where it undergeoes the same treatment to recover the lithium in lit hiophosphate form.

The industrial irmplementation method in a cortinuous process was dessigned on the basis of pilot tests at a size of 10 kg /ho ur attesting to the operattional and industrializable nature of the invention as set out in figures 3 and 4.

The- following description deals \with a method for applying the present invention to lithium-ion batteries withosut this having an exhaustive nature. The mechanical treatment 1 is performed in a tight chamber wherein two mills are arraanged in series. After the chamber has been scavenged by means of a gas composed of 20 % argon and 8&0 % carbon dioxide, 10 kg of mixed cells and batt eries are input in continuous manner via a double air-1 ock. The gases output from 1 are treated at 2 by leaching with water and neutralization by means of soda. The homogenate is extracted by means of an endless screw via a double air-l ock. It then undergoes physical treatment 3 by mea ns of a high-induction magnetic separation and a denssimetric table. On completion of this treatment, the fine and dense charge is cosmposed of lithium cobaltr te, carbon and lithium carbonate as shown by the X-ray diffraction spectrum pre sented in figure 2. It is trea ted by leaching with watear at 4 to recover the soluble lithium. After soliciliquid separation, the sol ution is sent for recovery of the lithium by precipitation at 5 whereas the solid fraction of cobaltlite 6 is recyclable in met allurgy in processes where c obalt has to be added. Th e characteristics are:

To illustrate the feasibility of ttme whole method emanating from the present inve ntion, the solid fraction 6 ressulting from the treatment 5 is sent for acid leac=hing 7. After dissolution of the lithium cobaltite, the solution is filtered to separate the carbon and is then purified from the metals other than cobalt at 8.

The cobalt sulphate and lithium ssolution 9 is then separate=d into two fractions. A first fraction is subjected to electrolysis 10. On completion of this electrolysis, cobalt cathodes are obtained ard also a solution poor im cobalt sulphate and enriched in sulphuric acid 11 that is sent to leaching input. The =second fraction is oxidized by means of sodium hypochlorite at 12 to obtain a trivalent cobalt hydroxide. The solution then no longer co ntains any lithium sulphate which is sent to 5 fom precipitation of the lithium phosphate.

In this impl-ementation, recycling of the lith ium cobaltite is well Foroven in three different tre=atment channels (cobaltite as iss, cobalt cathode and trivalent cobalt hydroxide). The three channels being illust rated as to their indusstrial feasibility, the choice will depend on the capacity of thee installation and on ®&he proximity of the recyclin g channels.

Extension to the recovery of the PF6 ani on:

It is commomnly recognized that the salt LiPF 6 breaks down in wat er as follows:

LiFPg +H20~> LiF + HF + POF,

This results in the PF, anion disappearing and in gas being rele=ased above the aqueous solution. During our experiments, we ascertained that: when treating mixed battesries and cells with a Li-SOCI. and Li-MnO, or Li—lons base, no emission took place. This confirms the stability of LiPFe in ag ueous solution under our conditions. We then sought to confirm the presence of the PF, anion by analysis— The hydrolysis solutions recovesred at 4 (figure 3) we=re analyzed by

Nuclear Magnetic Resonance (NMR) using scanning at 188.3 MHz for fluorine 19 and at 8.1 MHz for phosphorus 31. It is known that phosphorus resonates in the form of a heptet and fluorine in the form of a doublet. The values of constants and the chemical displacements of 19F and 31P (figures 5 and 6) enable the FPF, ion to be identified in an aqu eous solution without any ambiguity.

We deduce=d therefrom that one of the components provided toy the chloride cells played the stabilizing role of the PFs anion. These compomnents are SO;,

HCI, LiCl ard AICl,. Our complementary te sts to study the stabi lity of LiPF6 in the presencse of these components showed that LiCl plays the role of stabilizer of LIPF6 in aan aqueous solution.

As the PFg anio-n is stable in our aqueous solutions, we looked for poss ible ways of recover ing it. The state of the art did not show any known way for precipitating the PF ion in aqueous effluents. Studying the solubility of varieous

PF, salts led us too seek for a cation enabling th e hexofluorophosphate ion tos be quantitatively prescipitated. This precipitation was conducted in an aqueous medium from ou r stabilized solutions. We direxcted our studies towards lar-ger cations than the lithium cation. As the solutioms are stabilized by the chlor-ide anion, we tried the chlorides of alkaline cations such as ammonium. "The solubilities obtairmed are:

It became appareent that the solubility depends, among other things, on the ssize of the cation as s=hown by the following table setting out the solubility versus the ionic radius:

The lowest solubilities are achieved with very o nerous cations such as Cs aand

Rb, incompatible with an industrial application. "The solubility achieved with the ammonium ion (0.43 MIL, ie. 3.3 g/l) remains insufficient for quantit ative recovery. We therefore nad to direct our research towards larger cations. Ass the solubility obtained with the ammonium ion is however rather low, we then mused quaternary ammonium salts of the R,N* type (with FRR= methyl, ethyl and bmutyl).

These products are extensively used, in particular In industrial manner ard in particular as cationic surfactants in the detergent industry. The solubi lities obtained are all lower than those obtained with the ammonium ion but remmain higher than 8x10° M/ (i. €. 1.2 g/l). We then explored other larger cations ard in particular those reputed to give relatively low solubilities with the perchlorates ion the configuration whereof is close to that of hexafluo rophosphate. Better results than the previous ones vwvere obtained with two catiorys which are: . + - the hexamine complex of nickel : [Ni(VH, )6 F - and dihydro-l,4-diphenyl-3,5-phenylimino-1,2,4-triazole (Merck Index N° 12,6711) : _ N —T + - |@ as xX

The solubilities obtained at room temperature are s< 200 mg/l for the hexarmine complex of nickel and s=< 20 mg/l for the Dihydro-|,4&-diphenyl-3,5-phenylinino- 1,2,4-triazole.

Extension to recovery of new lithium iron plwosphate-based catheodic materials.

The cathodes of lithium-ion batteries marketed at present are lithium cobaltite base. However, the cost and toxicity of cobalt on the one hand and the safety problems that may result from the use of cobaltite on the other hand have led to large research efforts being made to develop new cathodic materials. Accor ding to the state of the art, the most promising material seems to be lithium iron phospheate (LiFePO,). We synthesized lithium iron phosphate aeccording to A.

Yamda et al. Journal of Electrochemical Society, volume 148 N°3 pA224 (2001).

Then wre proceeded to treat this compound as a cathodic mass 6 resulting from the phyrsical-chemical treatment as des cribed in figure 3.

The material is placed in solution in a 2N sulphuric medium at 80°C in the presence of steel shot with an iron/cathodic mass ratio of 0.15 . The solution obtained is cooled to 60°C and the=n oxidized by means of 30% volume hydrogenated peroxide at pH 3.85. Tie iron is then separated in the form of oxyhyd roxide of the ghoetite type. The lithium solution is then treated according to the rmethod described in 5 in figure 3 /5. By this method of imple -mentation, the iron, lithium and phosphate of the cathodic material are recovered. By this method of implementation, the method remains applicable wherm modifications take place in the composition of lithiurm batteries with a change i n the cathodic composition.

Claims

1. Method for hydrometallurgical treatment of cells and batteries ccmprising at least a Hithium-based anode, a salt dissolved in an electrolyte and a cathode comprising at least a metal or a combination of metals selected f rom cobalt, nickel, rmanganese and iron, for recove=ring the recoverable fractio ns, method charactesrized in that it comprises dry crushing at room temperature= in an inert atmosphere, treatment by at least mag netic separation and densirmetric table followed by aqueous hydrolysis, for thee purposes of recovering at least the lithium ir the form of carbonate or lithio phosphate, an anion of saicd electrolyte salt and a concentrate comprising at leasst one metal of said cathode.

2. Metlhod according to claim 1, characterized in that crushing is p erformed in an atmomsphere formed by a gas selectexd from argon and carbon dioxide or a mixture of argon and carbon dioxide in respective proportions of 10 % to 90 % of argon and 90% to 10% of carbon diox#de.

3. Method according to claim 2, characterized in that the proportion. of argon in the argo n and carbon dioxide mixture is from 10 % to 35 %.

4. Metkod according to any one of the claims 1 to 3, characterized in that crushing is performed by means of tvvo successive mills the first of which operates at a maximum speed of 11 rpm and the second of which operates at a speed of less than 90 rpm.

5. MetEd according to claim 4, characterized in that the first mill is a rotary shearing mill whereas the second mill is an impact mill.

6. MetFod according to any one of the claims 1 to 5, characterized in that the homoge nate resulting from the crushing operation is treated by a device that combine=s sieving to 3 mm followed boy sieving to 500 micrometers, high- inductior magnetic separation and a dermsimetric table and screening in order to

18 | To separate from the homogenate in a single run, a rmagnetic fraction, a den se non-magnetic fraction, a m agnetic fraction with a low density and a fine fracti-on at least rich in metal oxides ..

7. Method according to claim 6, characterized in thmat the fine fraction, form-ed the sieving undersized, is treated by leaching witih water to recover soluble lithium in the form of lithiopkosphate.

8. Method according to claim 7, characterized im that precipitation of the lithiophosphate is obtained by double modification of the pH by means of soda and phosphoric acid.

9. Method according to ore of the claims 7 and 8, characterized in that the fime fraction, from which the soluble lithium has been removed and comprising at least the cathode composed of at least a metal or &a combination of metals, is dissolved in a 2N sulphuric medium at a temperature of 80°C in the presence of steel shot in a ratio betwee the iron and the fine frac=tion from which the soluiole lithium has been removed of 0.15.

10. Method according to claim 9, characterized in that the solution resultimg from acid attack of said cathode and after purificatiomn by selective precipitation of the metallic impurities is subjected to electrolysis at a temperature of 55=C under a current density comprised between 400 and 600A/m? using tvwo electrodes made of stainless steel and antimony-lead alloy.

11. Method according to claim 9, characterized in tha_t the cobalt-rich solution in the case of a cobalt-based cathode attack is treated using hypochlorite after tthe pH has been regulated to & value comprised between 2.3 and 2.8 to obtain a trivalent cobalt hydroxide.

12. Method according to claims 1 to 11, characte=rized in that the anion of the electrolyte salt being hexafluorophosphate PF, said anion is stabilized im an aqueous solution by means of LiCl.

13. Method according to claim 12, ch aracterized in that the hexafluorophosphate PF, anion is recovered bwy precipitation by means of simple ammonium salts, quaternary ammonium, ammoniac nickel complex or Dihydro-l,4-diphenwl-3,5-phenylimino-1,2,4-triazol.

14. Method according to claims 1 to 9, characteri=ed in that the cathode besing LiIFePO4-based, it is treated by means of 2N sulphuric acid at 80°C and t-hen with 30% volume hydrogenated peroxide at 60°C to separate the iron from the lithium and phosph ate.