Advanced fuming

Abstract

The invention is in the field of pyrometallurgy and describes a process for the recovery of lithium by fuming. The process comprises smelting Li-ion batteries or their waste in a furnace with slag formers, resulting in a molten bath with distinct alloy and slag phases, and flue dust. Notably, at least 30% of the lithium is transferred to the flue dust under the chosen conditions without adding alkali or earth alkali halides. Li can then be recovered from the flue dust, valuable metals, such as Co and / or Ni, can be recovered from the alloy, and the remaining slag can be used in new smelting or Li- fuming operations.

Description

[0001] Advanced Fuming

[0002] The invention is in the field of pyrometallurgy and describes a process for the recovery of lithium by fuming.

[0003] Pyrometallurgical processes can be used for the recycling of Li-ion batteries. In such processes valuable metals are concentrated in an alloy phase, while other compounds, such as lithium, are typically concentrated in a slag phase.

[0004] There are few known processes for recycling Li-ion batteries, wherein valuable metals, such as nickel, cobalt and copper, are reduced to metal and concentrated in an alloy phase, while lithium goes to the gas phase at high temperature. Such a process is known as “fuming” of lithium.

[0005] Hu et al. (Recovery of Co, Ni, Mn, and Li from Li-ion batteries by smelting reduction - Part I: A laboratory-scale study: Journal of Power Sources, vol. 483, 2021 , 228936) conducted a laboratory-scale study on the recovery of Co, Ni, Mn, and Li from Li-ion batteries. It was found that Li vaporizes into the gas phase when de-coked electrode materials from batteries are melted with graphite at 1600 °C under a reducing atmosphere. During this process, Co, Ni and Mn are fully reduced, along with impurities such as Al, Fe, Si, forming an alloy phase. There was no or negligible amount of slag phase obtained due to full reduction of metals to an alloy phase. The authors conclude that this is substantially different from an industrial smelting reduction process, in which a slag phase is present to prevent the oxidation of molten alloy and for refining purposes. It is also described that Li is reduced to metal vapor orvolatile lithium halides in such reducing atmosphere. It is further concluded that a higher graphite content could reduce more LiAlO2 and let more volatile species of lithium be concentrated in the flue dust and that reducing conditions are beneficial to increase the Li fumingyield.

[0006] Hu et al. (Recovery of Co, Ni, Mn, and Li from Li-ion batteries by smelting reduction - Part II: A pilot-scale demonstration: Journal of Power Sources, vol. 483, 2021 , 229089) also performed smelting of Li-ion batteries in an Electric Arc Furnace. The experiments were performed under reducing conditions, and consequently 85.3 - 91 .5% of Mn contained in the Li-ion batteries was reduced and concentrated in the alloy phase. CaO based slag formers, such as lime and dolomite, were added to decrease the melting point of the slag, compensating the alumina originating from the electrode materials, which would otherwise increase the melting point of the slag to a level where a smelting process becomes challenging. The obtained slag was an Al2O3-CaO-SiO2-Li2O system containing less than 0.53 wt% of MnO. It is reported that under these process conditions around 60-70% of the Li was recovered in the EAF flue dust, while the other 30-40% of the Li was lost in the slag. The prior art teaches that a lower Li yield is attributed to a lower CaO / AI2O3 ratio in the formed slag. It is also reported that the better Li fuming yield was achieved with a ratio of CaO to AI2O3 of 1 .8, compared to 0.8. It was suggested that the Al content in Li-ion batteries needs to be reduced to a minimum level. Otherwise, the formed alumina has to be neutralized in the slag and, consequently, increases the slag volume.

[0007] The above prior art shows the results in a Tamman furnace or Electric Arc Furnace without injection of any gases.

[0008] EP4347906 B1 and Ren et al. (Recovery of valuable metals from spent lithium-ion batteries by smelting reduction process based on MnO-SiO2-Al2O3 slag system, Advances in Molten Slags, Fluxes, and Salts: Proceedings of the 10thInternational Conference on Molten Slags, Fluxes and Salts, 2016, pp. 211 -218) describe processing of Li-ion batteries to recover Ni and Co in the alloy phase while enriching Mn in the slag phase with limited addition of flux. Both are silent about fuming of Li.

[0009] KR102559495B1 describes a process, in which a major part of lithium is fumed as LiCI from a molten slag. Key of the invention is the addition of a fuming agent, such as alkali and / or earth alkali chloride, to fume the Li.

[0010] Alternatively, Li fuming can be done by addition of fluoride compounds instead of chloride compounds.

[0011] Fuming of Li is typically not mentioned in the prior art of classic battery recycling, which has a clear focus on the recovery of valuable metals, such as Co and Ni, in an alloy phase. This typically requires (strongly) reducing conditions. If Li fuming is mentioned in this context, reducing conditions are considered beneficial for the fuming of Li. Few processes describe Li fuming in more detail, typically including the addition of chlorides or fluorides as fuming agents.

[0012] It is therefore an aim of the present invention to provide an alternative process for the recovery of Ni and Co from Li-ion batteries or their waste, which also allows to recover Li from the slag by fuming.

[0013] A first aspect describes a process for the recovery of lithium comprising the steps:

[0014] -feedingto a furnace a charge comprisingslagformers and Li-ion batteries ortheirwaste, wherein the Li-ion batteries or theirwaste contain Ni and / or Co, Li, Mn and Al;

[0015] - smelting the charge, thereby obtaining a molten bath with an alloy phase and a slag phase, and flue dust; wherein the slag phase comprises a composition accordingto:

[0016] LiO > 1%;

[0017] 4% < MnO < 60%;

[0018] CaO / Al2O3< 1.5; MnO / Al2O3> 0.15;

[0019] 0.3 < Al2O3 / (Al2O3+ MnO + CaO) < 0.75 ; and, wherein Li contained in the molten bath charge is transferred to the flue dust by fuming without addition of alkali and / or earth alkali halide to the step of smelting.

[0020] The above percentages are understood as percentages by weight.

[0021] Li-ion batteries or their waste typically contain Ni, or Co, or both. Additionally, Li, Mn and Al will be present. Often also Fluorine (F) or other halides are contained in those Li-ion batteries as component of binder (between CAM and collector) and / or electrolyte. Typically, the amount of halide (such as F) contained in those Li-ion batteries, is sufficient to fume at least 30% of Li contained in the charge under the chosen process conditions. Which is then transferred to the flue dust.

[0022] Therefore it is preferred that at least 30% of the Li contained in the molten bath charge is transferred to the flue dust by fuming without addition of alkali and / or earth alkali halide to the step of smelting.

[0023] “Without addition” or“no addition” of alkali and / or earth alkali halide means that no such (external) halide is added before or during the step of smelting, relying instead on halides already present in the battery feed.

[0024] Minor impurities, potentially present in chemicals, are not considered as “additional halide additions”. In relation to the total weight of the charge this means less than 0.1 wt%, preferably less than 0.01 wt%.

[0025] The above-mentioned prior art teaches Li fuming in (strongly) reducing conditions, consequently concentrating a significant amount of Mn in the alloy phase. Mn reduction to the alloy requires intense reducing conditions, such as a pO2of 10^ 2 (i o to the minus 12), in which the reaction of Li-ion batteries or their waste in the furnace becomes endothermic and external heat has to be supplied to maintain the operational temperature.

[0026] To obtain battery grade Ni and Co salts from the alloy resulting from such an operation, Mn is typically separated by leaching. This is followed by expensive refining technologies, such as solvent extraction, generally increasing the operational costs. Furthermore, the value of Mn is much less compared to Ni and / or Co, which makes the separation of Mn less appealing in an industrial setup.

[0027] To avoid thattoo much Mn is reduced to the alloy phase, oxidizing conditions are applied, so that metals such as Mn preferably stay as oxides in slag phase. A MnO-rich slag composition minimizes the flux addition, and allows that the slag volume is kept low. Therefore, the slag phase comprises at least 4% MnO. At least 8% MnO are preferred. The above-mentioned prior art also suggests to keep a high CaO to AI2O3 ratio in the obtained slag, but this will increase the volume of obtained slag due to addition of a large quantity of CaO, and consequently more Li remains in the slag.

[0028] A higher CaO to AI2O3 ratio (for example by addition of limestone) will also result in more CaO being carried over to the flue dust, resulting in dilution of the Li concentration in the flue dust and therefore complicating Li recovery from the flue dust.

[0029] Keeping the ratio of CaO to AI2O3 at less than 1 .5 helps to limit the amount of slag and also to avoid a too high operation temperature. Higher operation temperatures increase the risk of refractory wear.

[0030] The same applies for the condition 0.3 < Al2O3 / (Al2O3 + MnO + CaO) < 0.75.

[0031] In a further aspect, smelting the charge is performed at a p©2 of 10" (10 to the minus 7) to 0 to the minus 1 1 ) atm, preferably at a p©2 of 10"® to 10"1 ® atm.

[0032] These conditions distinguish from strongly reducing conditions often applied in prior art processes, i.e. they are more oxidizing. An indication for this is also the pronounced content of manganese in the slag, namely 4% < MnO < 60% or 8% < MnO < 40%.

[0033] On the other hand, applying too oxidizing conditions may lead to a too high heat generation.

[0034] In a further aspect, the ratio of Li to Al in the charge is 0.15 or more.

[0035] This condition has a positive impact on Li fuming as the slag quantity is reduced, and also excess heat generation by oxidation of Al is avoided.

[0036] A further aspect describes a process according to the first aspect, wherein the slag phase comprises at least 50% of the Mn contained in the charge, or at least 80% of the Mn contained in the charge.

[0037] Under the chosen reaction conditions, particularly the oxidation level pC>2, at least 50% of the Mn contained in the charge reports to the slag. Preferably at least 80% of the Mn contained in the charge reports to the slag, indicating more oxidizing conditions.

[0038] The obtained slag typically contains P2O5 in a range of 0.5% < P2O5 < 10%.

[0039] A further aspect describes a process according to the first aspect, wherein the slag phase has a composition by weight accordingto AI2O3 + SiC>2 + CaO + Li2O + MnO + FeO + MgO + P2O5 > 85%.

[0040] In a further aspect, smelting the charge is performed at a temperature of 1300-1650 °C. A temperature of 1450-1600 °C is preferred, a temperature of 1500-1550 °C more preferred. In a further aspect, the process is further comprising, subsequent to the step of smelting, a step of adding an amount of an alkali and / or earth alkali halide (Hal) to the molten bath, wherein the amount of halide is determined by the formulae: (Lic) - (Lid)=(Lis)and (Hal) a 1 .1 *(Lis); and wherein (Lic) is the total amount of lithium in the charge, (Lid) 'sth® amount of lithium in the flue dust, and (Lis) the amount of lithium in the slag.

[0041] In this regard it is convenient to determine the amount of lithium in the charge (Lic) upfront, for example by chemical analysis, then analyze the amount of lithium in the flue dust (Lid) during the process, and calculate the remaining amount of lithium in the slag (Lis), rather than having to perform an additional analysis from the hot slag. It is of course equally possible to take a sample from slag and estimate Li(s).

[0042] Based on (Lis) a stoichiometric excess of halide (Hal) is chosen, such as 110% or more, to allow an almost complete fuming of Li from the slag. Preferred conditions are (stoichiometric) 130% or more of (Hal), or 140% or more of (Hal), or 150% or more of (Hal). Amounts of 160% or more of (Hal) typically do not have an additional beneficial effect on the fuming yield anymore and only increase the cost of the process. (Hal) is typically a chloride or fluoride.

[0043] This optional addition of halide can then be considered a “two-step fuming process”, i.e. first fuming without addition of halides according to the first aspect, followed by subsequent fuming with addition of halides. This allows to use overall less halides, as compared to a process wherein the amount of halide is chosen based on a stoichiometric excess with regards to the total amount of Li in the charge.

[0044] For example by addition of a chlorination agent, such as CaCl2, remaining Li in the slag is converted to LiCl. While a fuming according to the present invention can decrease the Li2O content in the slag to about 7-10 wt%, a chlorination can further decrease the content of Li2O in the slag to about 1 wt %. This refers to the concentration of Li2O in the entire slag.

[0045] Optionally, this can even be done in a separated furnace, operating under different, probably more reducing conditions.

[0046] Compared to the known chlorination fuming using CaCl2, the combination of fuming accordingto the present invention and chlorination fuming can reduce the consumption of chlorination agents (e.g. CaCl2), making the process more efficient.

[0047] In a further aspect, the alkali and / or earth alkali halide (Hal) is NaCl, KCl , CaCl2, MgCl2, NaF or CaF2-

[0048] In an industrial setup the focus is more on the commonly available chlorides. Fuming with the respective fluorides is equally possible, but less preferred for practical reasons, especially the follow-up treatment of flue dust and off gases, as also unwanted HF can be formed.

[0049] In a further aspect, the process is further comprising the steps:

[0050] - separatingthe alloy phase and the slag phase; and,

[0051] - acidic leaching of the alloy phase, thereby obtaining the majority of Ni and / or Co in solution.

[0052] Under the conditions of the present invention, the alloy contains less than 5% Mn.

[0053] The acidic leaching is typically done after letting cool down the (separated) alloy phase, preferably to room temperature.

[0054] Typically, the alloy is leached in inorganic acid, such as H2SO4 or HCl.

[0055] For some metals, such as copper, additionally an oxidizing reagent might be needed.

[0056] There are multiple options for the acidic leaching.

[0057] Therefore, in a further aspect, the alloy is fully leached, with subsequent separate steps for removal of contained Cu and / or Fe, and one or more of Co, Ni, and Mn (the typical NMC metals).

[0058] In a further aspect, Co, Ni, and / or Mn are selectively leached together with Cu, while the majority of Fe is rejected.

[0059] In a further aspect, Co, Ni, and / or Mn are selectively leached, while the majority of Fe and Cu is rejected.

[0060] Selective leaching can for example be achieved by controlling the pH (amount of acid added) or by controlling the amount of oxidizer added.

[0061] Solvent extraction (SX) can optionally also be applied to separate impurities or selected metals.

[0062] Last step is typically a crystallization or a precipitation of valuable metals such as Co and / or Ni. Or, also a removal of the aqueous solvent is possible, especially if the solution is pure enough. Therefore, in a further aspect, the process further comprises a step of crystallizing or precipitating of Ni and / or Co from solution. Conditions for either crystallizing or precipitating are well known to the skilled person.

[0063] Alternatively, the alloy phase can be separated from the slag phase before adding an amount of an alkali and / or earth alkali halide (Hal). Further treatment of the separated alloy phase as described above. A further aspect therefore describes a process according to the first aspect, further comprising a step of separating the alloy phase from the slag phase, thereby obtaining a lithium-containing slag depleted in Ni and / or Co.

[0064] This alternative has advantages. After separation of the alloy phase, the metals contained in the alloy, such as Co and / or Ni, can no longer react with alkali and / or earth alkali halide (Hal) to form respective metal-halide compounds. Also Cu, often present in battery materials, is known to react for example with CaCl2 to form gaseous CuCl at high temperatures. It is therefore advantageous to avoid metals in the slag, respectively remove at least part of them upfront, when aiming for a more efficient Li-fuming process. In the present process, such side-reactions are efficiently suppressed and the amount of (Hal) to be added to the process can be lowered.

[0065] The same is true for reactions of alkali and / or earth alkali halide (Hal) with water, originating for example from the feed (wet cake; black mass) or from the burner. Reaction with water causes a loss of fuming agent (Hal) due to the competing reaction between (Hal) and water, forming compounds such as HF, HCl or HBr. This does not only increase the consumption of the fuming agent, but also decrease the Li recovery yield. The reaction between fuming agent and water becomes especially prioritized when the Li content in slag is low.

[0066] After smelting, the lithium-containing slag is essentially water-free, as aqueous impurities are evaporated. As a result, the amount of (Hal) to be added to the process can be lowered further.

[0067] In this process setup, both effects -avoiding metals and avoidingwaterto react with (Harare adding up.

[0068] In a further aspect, the furnace according to the first aspect is an electric furnace. Such an electric furnace is also known as EAF (= Electric Arc Furnace).

[0069] It is equally suitable to transfer the lithium-containing slag from any type of furnace used for smelting to an EAF after separating the alloy phase from the slag phase. This separated furnace can thus even work under different conditions, as already mentioned above. Those conditions can preferably be more reducing conditions, such as having a pC>2 range of 10‘9 to 1 cH 3 atm, preferably 1 cH 1 to 1 cH 3 atm.

[0070] In the present process, using an EAF has further advantages. In addition to startingthe Li- fuming from a dry (i.e. water-free) and metal-depleted slag, the extremely high temperatures between electrodes promote evaporation of Li-halides, such as LiCl. Consequently, the total yield of fumed lithium is increased, while the residual lithium in the slag is minimized.

[0071] A further aspect describes a process, wherein the flue dust comprises a composition by weight according to: 5 % < Li < 30% and 10% < F < 55%, and, wherein the molar ratio of Li / F is 0.1 or more.

[0072] In a further aspect, the process further comprises a leaching of the flue dust, wherein the leaching comprises carbonation leaching or acidic leaching, and an addition of CaCl2.

[0073] The obtained flue dust can be processed using either a combination of carbonation leaching followed by the addition of CaCl2, or acidic leachingwith CaCl2 addition.

[0074] Carbonation leaching is a process wherein carbon dioxide (CO2) is used to leach metals from the flue dust. The (CO2) is dissolved in water to form carbonic acid (H2CO3), which then reacts for example with Li compounds. Carbonation leaching is particularly suitable for flue dust containing a high quantity of Li2CO3, as it effectively dissolves Li2CO3 into the solution.

[0075] Acidic leaching with CaCl2 addition is particularly suitable for flue dust containing both Li2CO3 and LiF, as it converts Li into soluble LiCl while fixing F as CaF2> resulting in its precipitation.

[0076] Soluble compounds are then separated from the solid material.

[0077] A further aspect describes a flue dust comprising a composition by weight according to 5 % < Li < 30% and 10% < F < 55%, and, wherein the molar ratio of Li / F is 0.1 or more.

[0078] Fluorine (F) is typically contained in batteries, for example in binder or electrolyte. Compared to that, chlorine (Cl) is less typical, and can be found only in minor amounts or will even be absent. Focus for the fuming according to the first aspect is therefore on the fluorides. Optional later additions and subsequent fuming can of course be with any suitable halide (Hal).

[0079] Analysis shows that under the conditions of the present invention the flue dust can contain different Li species, such as LiF, LiCl, Li2CO3 or Li2O, all obtained in the fuming process. Independent of the exact chemical composition, the fuming process achieves a concentration of lithium in the flue dust, which makes any follow-up operation much easier compared to isolatingthe lithium from a slag, in which it is rather diluted.

[0080] A molar ratio of Li / F of 0.1 or more has been observed in the present process.

[0081] Flue dust is typically collected in the so-called off-take zone or gas cleaning system of a furnace. All types of equipment can be installed in the off-take zone, such as a dustcatcher, baghouse filter, cyclone separator, electrostatic precipitator, scrubber, Venturi scrubber or condenser. Alternatively, parts of the off-take zone can be named by a specific function rather than by referring to a specific equipment, for example cooling zone (cooling section), condensation zone (condensation section) or the like.

[0082] When top-feeding the charge, typically so-called “entrainment” can be observed, especially when the charge is in the form of a powder. In the context of a furnace, entrainment refers to the unintended transport of parts of the feed materials into the offtake zone of the furnace. Thus, even if metals like Ni or Co do not fume from the molten bath, nevertheless traces of them can be found in the flue dust. Under the conditions of the present invention, the following (varying) percentages have been found in the flue dust:

[0083] 0.04% < Ni < 5.2%

[0084] 0.02% < Co < 5.4%

[0085] 0.02% < Cu < 5.3%

[0086] 0.01 % < Mn < 3.5 %

[0087] 0.1 % < Al2O3< 3.5 %

[0088] 0.1 % < CaO < 8.5 %

[0089] 0.2 % < P2O5< 6.5 %

[0090] Examples of factors that can have an influence on the entrainment: a) Gas Flow Rate: Higher gas flow rates can increase the velocity of the gas, which can carry more particles into the off-take zone. b) Particle Size: Finer particles of the feed material are more easily entrained because they have less mass and are more susceptible to being carried by the gas flow. c) Other Feed Material Properties: The physical and chemical properties of the feed material, such as the moisture content, can influence how easily particles are entrained. d) Operational Conditions: Conditions such as temperature and pressure within the furnace can also play a role in entrainment. e) Furnace Design: The design of the furnace, including the shape and size of the off-take zone, can impact the flow dynamics and the likelihood of entrainment.

[0091] A further aspect describes a process, wherein an 02-bearing gas is introduced into the molten bath by submerged injection.

[0092] Submerged injection creates turbulences in the molten bath, leading to better mixing of the injected gases with the molten material and a larger amount of carry-over gas from the molten bath, which can improve the efficiency of reactions, particularly also of Li fuming.

[0093] Moreover, submerged injection can improve the heat transfer within the molten bath, helping to maintain a consistent temperature and reducing the risk of localized overheating.

[0094] Submerged injection also allows more flexible control of the pC>2, thus for example also keeping Mn in oxidized form is less challenging.

[0095] Submerged injection is especially powerful when applied to a feed with high carbon content, giving precise control of the pC>2.

[0096] A further aspect describes a process, wherein an 02-bearing gas is introduced into the molten bath via at least two different injection points.

[0097] The at least two injection points create more turbulence in the molten bath, enhancing the mixing of the molten material. This leads to a more uniform temperature and composition throughout the bath. Moreover, better mixing can improve the efficiency of reactions, particularly also of Li fuming.

[0098] Generally, the process can be better controlled, for example with regards to temperature and the desired pC>2 level.

[0099] A further aspect describes the use of the obtained slag as slag former in a process according to the first aspect, thereby partially or fully replacing slag formers in the step of feeding.

[0100] Re-using the obtained slag in new operations allows for a greater flexibility in choosing operating conditions, such as the pO2-level of the process. For example, when more oxidizing conditions are used, thereby sending more Co and / or Ni to the slag, these valuable metals would be recovered in a following operation cycle, where more reducing conditions could be used to recover more of the Co and / or Ni.

[0101] “Li-ion batteries or their waste” are, for example, new or waste Li-ion batteries, spent or end-of-life batteries (EOL), production or battery scrap, electrode materials or pre- processed battery materials, such as after shredding or sorting. Also “Black Mass” is explicitly understood to fall under “Li-ion batteries or their waste”.

[0102] "Black Mass" (BM), "Black Matter" or “Black Powder” is a very interesting starting material for recycling via smelting processes. The expression "Black Mass" is typically used in industry to describe an intermediate product originating from Li-ion batteries or their waste. For example, black mass may be produced through shredding and separation of pyrolyzed end-of-life (EOL) lithium ion batteries, or in another example through shredding EOL lithium ion batteries with water, followed by drying and separation, or in another example by shredding and separation of production scrap of lithium ion batteries. It is thus clear that while the expression Black Mass is frequently used in industry, the exact composition of these materials may vary significantly, depending on producer or application.

[0103] Black mass typically contains the majority of the cathode materials and anode materials of the batteries, together with fractions of other battery components. The resulting Black Mass is typically a fine, often black, powder material.

[0104] In the context of this invention, Black Mass is defined as a powder obtained from Li-ion battery materials ortheir waste, which contains appreciable amounts of Li, Co and / or Ni.

[0105] The following examples illustrate the invention and are not intended to limit the scope of the invention in anyway.

[0106] EXAMPLES

[0107] Example 1

[0108] 500 kg of Black Mass together with 2 kg of limestone was fed to a furnace with a diameter of 1 m. A bath temperature of 1500-1550 °C was maintained, which is suitable to maintain both the slag and the alloy sufficiently fluid for easy tapping and handling. The heat was supplied by the oxidation of Al and C in the Black Mass, using submerged O2 injection. The injection rate was chosen to have a pC>2 of 10"®. Natural gas was added to compensate for heat losses in the furnace. After 1 hour of heating, the produced alloy and slag were separated by tapping.

[0109] Table 1 shows the analyses of the input and output phases of the process. The remaining percentages in the Black Mass are typically hydrogen, oxygen, and organic compounds. Li in the slag was present as Li2O. The remaining percentages in the flue dust are typically carbon and oxygen, for example in the form of Li2CC>3, as well as H2O due to the hygroscopic nature of the flue dust. Carbon content is typically not measured in the flue dust. Under the chosen process conditions, significant quantities of flue dust were captured.

[0110] Table 1

[0111] Input

[0112] Composition (%)

[0113] Input Al Mn P

[0114] Ni Co Cu SiO2 CaO Li F C

[0115] (AI2O3) (MnO) (P2O5)

[0116] Black Mass 14.5 4.8 3.1 4.5 3.1 2.2 4.5 0.4 26.5

[0117] Limestone 4.8 53.3 11.4

[0118] Output (wt%)

[0119] Alloy 63.7 21.1 13.5 0 0 0 0 0.8 0

[0120] Slag 0.9 0.3 0.2 0.1 1.2 (51 .0) 3.2 (33.6) (1.5)

[0121] Flue dust 2.9 1.5 0.9 0.0 0.1 (1 .7) 25.7 43.6 (0.6) (1.1)

[0122] Conclusion: The example shows that an alloy phase was produced containing 63.7 wt% Ni, 21.1 wt% Co and 13.5 wt% Cu. The CaO / A^Og ratio of the slag produced was 0.02 and it contained 33.6 wt% of MnO. Flue dust was also produced, which contained 25.7 wt% Li. The high quantity of Li in the flue dust indicates that Li was fumed from the molten bath. The presence of Ni, Co and Cu in the flue dust indicates that a small amount of the feed material was carried to the flue dust (industrially known as: “entrainment” or “carry over”). The Li recovery from the feed to the flue dust was 82.6 wt%. Example 2

[0123] 500 kg of Black Mass together with 45 kg of limestone was fed to a furnace with a diameter of 1 m. A bath temperature of 1500-1550 °C was maintained, which kept both the slag and the alloy sufficiently fluid for easy tapping and handling. The heat was supplied by the oxidation of Al and C in the Black Mass, using submerged O2 injection. The injection rate was chosen to have a pC>2 of 10"®. Natural gas was added to compensate for heat losses in the furnace. After 1 hour of heating, the produced alloy and slag were separated by tapping.

[0124] Table 2 shows the analyses of the input and output phases of the process. The remaining percentages in the Black Mass are typically hydrogen, oxygen, and organic compounds. Li in the slag was present as Li2O. The remaining percentages in the flue dust are typically carbon and oxygen, for example in the form of Li2CO3, as well as H2O due to the hygroscopic nature of the flue dust. Under the chosen process conditions, significant quantities of flue dust were captured.

[0125] Table 2

[0126] Input

[0127] Composition (%)

[0128] Al Mn P

[0129] Ni Co Cu SiO2 CaO Li F C

[0130] Input (AI2O3) (MnO) (P2O5)

[0131] Black Mass 14.5 4.8 3.1 4.5 3.1 2.2 4.5 0.4 26.5

[0132] Limestone 4.8 53.3 11.4

[0133] Output (wt%)

[0134] Alloy 63.6 20.7 13.2 0 0 0.6 0

[0135] Slag 0.6 0.4 0.3 1.9 20.6 (37.6) 3.7 (24.8) (1.1)

[0136] Flue dust 2.9 1 .5 1.3 0.1 1.9 (1 .7) 22.5 43.5 (0.6) (1.1)

[0137] Conclusion: The example shows that an alloy was produced containing 63.6 wt% Ni, 20.7 wt% Co and 13.2 wt% Cu. The CaO / A^Og ratio of the slag produced was 0.55 and it contained 24.8 wt% MnO. Flue dust was also produced, which contained 22.5 wt% Li. The Li recovery from the feed to the flue dust was 72.6 wt%. Example 3

[0138] 500 kg of Black Mass together with 90 kg of limestone was fed to a furnace with a diameter of 1 m. A bath temperature of 1500-1550 °C was maintained, which kept both the slag and the alloy sufficiently fluid for easy tapping and handling. The heat was supplied by the oxidation of Al and C in the Black Mass, using submerged O2 injection. The injection rate was chosen to have a pC>2 of 10"®. Natural gas was added to compensate for heat losses in the furnace. After 1 hour of heating, the produced alloy and slag were separated by tapping.

[0139] Table 3 shows the analyses of the input and output phases of the process. The remaining percentages in the Black Mass are typically hydrogen, oxygen, and organic compounds. Li in the slag was present as Li2O. The remaining percentages in the flue dust are typically carbon and oxygen, for example in the form of Li2CO3, as well as H2O due to the hygroscopic nature of the flue dust. Under the chosen process conditions, significant quantities of flue dust were captured.

[0140] Table 3

[0141] Input

[0142] Composition (%)

[0143] Input Al Mn P

[0144] Ni Co Cu SiO2 CaO Li F C

[0145] (AI2O3) (MnO) (P2O5)

[0146] Black Mass 14.5 4.8 3.1 4.5 3.1 2.2 4.5 0.4 26.5

[0147] Limestone 4.8 53.3 11.4

[0148] Output (wt%)

[0149] Alloy 62.5 20.4 13.4 0 0 0 0 1 0

[0150] Slag 0.5 0.2 0.1 3.1 33.5 (30.6) 3.5 (20.0) (0.9)

[0151] Flue dust 2.4 1.6 0.5 0.1 3.2 (1 .4) 17.4 48.1 (0.5) (0.9)

[0152] Conclusion: The example shows that an alloy was produced containing 62.5 wt% Ni, 20.4 wt% Co and 13.4 wt% Cu. The CaO / A^Og ratio of the slag produced was 1.10 and it contained 20.0 wt% MnO. Flue dust was also produced, which contained 17.4 wt% Li. The Li recovery from the feed to the flue dust was 68.9 wt%.

[0153] In the provided examples, oxidative conditions were maintained to inhibit the reduction of manganese (Mn) into the alloy phase. This resulted in the Mn content in the alloy being very low, while the MnO content in the slag exceeded 15 wt%. All examples demonstrated a high recovery rate of Li in the flue dust under the chosen conditions of the present invention.

[0154] Increasing the CaO / Al2O3 ratio adversely affected both the Li yield and the purity of the flue dust, due to greater entrapment of Li in the slag and increased entrainment of Ca to the flue dust.

[0155] Example 4

[0156] 600 kg of slag derived from a previous metallurgical operation, containing 3.01 wt% Li, was charged into a pilot-scale electric arc furnace (EAF) with a diameter of 90 cm and a height of 130 cm. The furnace was equipped with dual top graphite electrodes and a DC power supply (1 MW theoretical capacity), and lined with direct bonded magnesite- chrome refractory. A bath temperature of 1500 °C was maintained.

[0157] CaCl2 was added at a rate of 25 kg / h, together with coke at 5 kg / h to maintain reducing conditions. The oxygen potential (pC>2) was controlled and kept at 10‘1 ensuring a reducing atmosphere favourable for LiCl volatilization. Samples were taken after the addition of approximately 0.87 eq. and 1.04 eq. CaCl2, followed by a 30-minute postreaction period without further additions. The results are shown in Table 4.

[0158] Example 4. EAF with Cokes

[0159] * Measurement taken after 30-minute post-reaction period without further additions.

[0160] Conclusion

[0161] This example demonstrates that LiCl fuming under reducing conditions in an electric arc furnace is highly effective. The process resulted in an exceptionally low residual lithium concentration of 0.03 wt% in the slag, corresponding to a lithium yield of 99% and a CaCl2 selectivity of 95%. These values confirm that nearly all lithium was successfully volatilized and recovered, with minimal interference from other slag components. The low oxygen potential (pO2 = 10"^ ) was suitable in promoting the formation of volatile LiCl and suppressing oxidation reactions that could hinder selectivity. The combination of high temperature, reducing atmosphere, and controlled CaCl2 addition led to outstanding lithium recovery and highly selective volatilization Example 5 (Counter-example)

[0162] 600 kg of slag derived from a previous metallurgical operation, containing 3.05 wt% Li, was charged into a cylindrical pilot-scale smelting furnace with a volume of 1 m3. The furnace was lined with refractory bricks and direct bonded magnesite-chrome refractory. Natural gas and oxygen were injected in controlled ratios to maintain a neutral flame (A = 1 ), with flow rates of 20-30 Nm3 / h for natural gas and 35-57 Nm3 / h for oxygen. A bath temperature of 1500 °C was maintained.

[0163] CaCl2 was added at a rate of 50 kg / h. The oxygen potential (pO2) was controlled at 10’8, resulting in a neutral atmosphere. Samples were taken after the addition of approximately 0.85 eq. and 1 .14 eq. CaCl2, followed by a 30-minute post-reaction period without further additions. The results are shown in Table 5.

[0164] Example 5. Smelter

[0165] * Measurement taken after 30-minute post-reaction period without further additions.

[0166] Conclusion

[0167] The example shows that LiCl fuming under neutral conditions resulted in a final Li concentration of 0.79 wt% in the slag, corresponding to a Li yield of 74% and a CaCl2 selectivity of 65%. These values are significantly lower than those obtained in Example 4. The higher oxygen potential (pO2 = 10‘8) enabled the oxidation of Cu, Ni and Co, allowing the formation of volatile chlorides such as CuCl, NiCl2 and C0CI2. This reduced the selectivity of CaCl2 towards lithium. In addition, the presence of H2O promoted HCl formation, further diminishing selectivity. Overall, the neutral atmosphere and furnace configuration led to lower lithium recovery and reduced process efficiency.

[0168] Example 6 (Counter-example)

[0169] 400 g of slag derived from a previous metallurgical operation, containing 3.80 wt% Li, was charged into a 2 L alumina crucible and heated to 1500 °C in an induction furnace. The furnace atmosphere was kept neutral under continuous Ar gas flow. One equivalent of CaCl2 was added gradually over one hour in 12 equal increments every 5 minutes. Prior to use, CaCl2 was dried at 150 °C to remove moisture.

[0170] After the final addition, the slag was allowed to react for an additional 30 minutes. Samples were taken before CaCl2 addition, after the final increment, and after the post- reaction period. The results are shown in Table 6.

[0171] Example 6. Induction Furnace

[0172] * Measurement taken after 30-minute post-reaction period without further additions.

[0173] Conclusion: The example shows that LiCl fuming in an induction furnace under neutral conditions resulted in a final Li concentration of 0.78 wt% in the slag, corresponding to a Li yield of 79% and a CaCl2 selectivity of 79%. These values are significantly lower than those obtained in Example 4. The absence of localized high temperatures limited the fuming kinetics, and the neutral atmosphere (pC>2 = 10"®) enabled the formation of volatile chlorides of Cu, Ni and Co, reducing the selectivity of CaCl2towards lithium. Overall, the process performance was inferior, confirming the superiority of the reducing conditions applied in Example 4.

Claims

CLAIMS1 . Process for the recovery of lithium comprising the steps:-feedingto a furnace a charge comprisingslag formers and Li-ion batteries ortheirwaste, wherein the Li-ion batteries or theirwaste contain Ni and / or Co, Li, Mn and Al;- smelting the charge at a pO2of 10" to 10"11 atm, thereby obtaining a molten bath with an alloy phase and a slag phase, and flue dust; wherein the slag phase comprises a composition accordingto:LiO > 1%;4% < MnO < 60%;CaO / Al2O3< 1.5;MnO / Al2O3> 0.15;0.3 < Al2O3 / (Al2O3+MnO+CaO) < 0.75; and, wherein Li contained in the charge is transferred to the flue dust by fuming without addition of alkali and / or earth alkali halide to the step of smelting.

2. Process accordingto claim 1 , wherein the ratio of Li to Al in the charge is 0.15 or more.

3. Process accordingto claim 1 or2, wherein the slag phase has a composition by weight accordingto Al2O3+ SiO2+ CaO + Li2O + MnO + FeO + MgO + P2O3> 85%.

4. Process according to any one of claims 1 to 3, wherein the slag phase comprises at least 50% of the Mn contained in the charge.

5. Process according to any one of claims 1 to 4, wherein the smelting is performed at a temperature of 1300-1650 °C.

6. Process according to any one of claims 1 to 5, further comprising, subsequent to the step of smelting, a step of adding an amount of an alkali and / or earth alkali halide (Hal) to the molten bath, wherein the amount of halide is determined by the formulae:(Lic) - (Lid) = (Lis) and (Hal) > 1.1*(Lis); wherein (Lic) is the total amount of lithium in the charge, (Lid) is the amount of lithium in the flue dust, and (Lis) the amount of lithium in the slag.

7. Process accordingto claim 6, wherein the alkali and / or earth alkali halide (Hal) is NaCl, KCl, CaCl2, MgCl2, NaF or CaF2.

8. Process according to any one of claims 1 to 7, wherein the flue dust comprises a composition by weight according to:5 % < Li < 30% and 10% < F < 55%, and, wherein the molar ratio of Li / F is 0.1 or more.

9. Process accordingto any one of claims 1 to 8, further comprising a leaching of the flue dust, wherein the leaching comprises carbonation leaching or acidic leaching, and an addition of CaCl2.

10. Process according to any one of claims 1 to 8, further comprising the steps:- separatingthe alloy phase and the slag phase; and,- acidic leaching of the alloy phase, thereby obtaining the majority of Ni and / or Co in solution.

11. Process according to claim 10, further comprising a step of crystallizing or precipitating of Ni and / or Co from the solution.

12. Process according to any one of claims 1 to 8, wherein an O2-bearing gas is introduced into the molten bath by submerged injection.

13. Process according to claim 12, wherein the O2-bearing gas is introduced into the molten bath via at least two different injection points.

14. Process according to claim 1 , wherein the slag is recycled back to the step of feeding in a new smelting operation, thereby partially or fully replacing the slag formers.

15. Process accordingto any one of claims 1 to 5, further comprising a step of separating the alloy phase from the slag phase, thereby obtaining a lithium-containing slag depleted in Ni and / or Co.

16. Process according to claim 15, wherein the lithium-containing slag is essentially water-free.

17. Process according to claim 15 or 16, wherein the furnace is an electric furnace or wherein the lithium-containing slag is transferred to an electric furnace after separating the alloy phase from the slag phase.

18. Process according to any one of claims 15 to 17, further comprising a step of adding an amount of an alkali and / or earth alkali halide (Hal) to the slag, wherein the amount of halide is determined by: (Lie) - (Lid) = (Lis) , wherein (Lie) is the total amount of lithium in the charge, (Lid) is the amount of lithium in the flue dust, and (Lis) the amount of lithium in the slag; and,(Lis) multiplied by 1 .0 to 1 .1 = (Hal), preferably (Lis) multiplied by 1 .0 to 1 .04 = (Hal).

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