Energy-efficient pyrometallurgical method for processing Li-ion batteries

Abstract

The present disclosure relates to a 2-step smelting method for recovering Ni and Co from batteries and other sources. The method comprises the following steps: - defining an oxidation level Ox and a metallurgical feed containing batteries; - oxidative smelting the metallurgical feed to a defined oxidation level Ox by injecting an O2-containing gas into the melt; and - reducing the slag obtained by smelting using a heat source and a reducing agent. The method is more energy efficient than a single-step reduction smelting method and provides a higher purity alloy and a cleaner final slag.

Description

[0001] The present invention relates to a method for recovering valuable metals such as Ni and Co from batteries and other sources. A Ni-Co alloy and a slag are produced.

[0002] In recent years, electric vehicles have experienced unprecedented growth, driven by new regulations in Europe and China, which are designed to gradually reduce the CO2 emissions of automobiles and limit air pollution in cities. This growth is expected to continue during the next few decades. The adoption of electric vehicles depends largely on the performance of the batteries used to store electrical energy. In order to obtain the highest energy density while keeping costs under control, Li-ion batteries are used. Many of these batteries contain positive electrodes based on the transition metals Ni, Mn and Co, and are therefore also called NMC batteries. As the electric vehicle market grows, the demand for these metals is expected to increase significantly.

[0003] The demand for Ni and Co may even exceed global production capacity. Co is particularly critical because it is currently produced only as a by-product of the Ni and Cu industries. The Ni market is significantly larger than the Co market. Most Ni is used to produce stainless steel, where purity is relatively unimportant. However, high-purity Ni and Co metals or compounds are already in short supply. In view of the above, recycling Ni and Co from scrapped batteries is an attractive proposition.

[0004] Many smelting methods have been proposed that allow metals to be recovered from waste batteries. Such methods generally produce alloys and slags. The alloys, if pure enough, may be suitable, for example, for the preparation of cathode materials for Li-ion batteries, thus completing the closed loop. The slags, if sufficiently depleted of heavy metals, may be suitable for use in the construction industry or for safe disposal.

[0005] However, obtaining pure alloys and highly depleted slag while saving energy is challenging.

[0006] In Europe, the Classification, Labelling and Packaging (CLP) Regulation EC N° 1272 / 2008 requires the labelling of all slags containing more than 0.1% of either Ni and Co as potentially hazardous materials. It then requires the end user of the material to carry out a risk analysis: this will impair or even prevent the reuse of such slags in most known applications.

[0007] When smelting metallurgical feeds containing Co and / or Ni, the content of heavy metals in the slag will generally exceed the above limits. For example, Elwert et al. (World of Metallurgy-Erzmetall, GDMB-Medienverlag, Clausthal-Zellerfeld, Vol. 65, No. 3, pp. 163-171, 2012) illustrate this point and discuss three typical slags and their detailed phase compositions.

[0008] The combined Ni and Co content of the slag can be further reduced to below 0.1% by increasing the reduction level. However, these reduction reactions are endothermic and, more importantly, require a reducing agent, which is most often carbon-based. The required reduction level means that C is burned to CO, rather than CO2. This greatly limits the enthalpy available for heating and melting the metallurgical feed, requiring the use of additional heating means.

[0009] WO2018073145 teaches the addition of Co-containing materials, such as batteries, to a Cu or Ni converter. The feed comprises mainly matte, i.e. metal sulfides. As is typical in a converter, the heat of smelting is generated by the oxidation of S to SO2. The enthalpy of this reaction is used to smelt a limited portion of the battery and sulfide feed.

[0010] WO2011035915 describes a high temperature method for treating spent Li-ion batteries, which produces an alloy containing Co, Ni and Cu and a slag. Energy is provided by oxidation of Al and C in such batteries, which corresponds to a spontaneous smelting process. In order to ensure such a spontaneous process, WO2011035915 teaches that the percentage of spent batteries in the total feed needs to be higher than 153%-3.5(Al+0.6C), where Al and C are the weight % of Al and C in the battery. The main source of Al in the battery comes from the casing material. Spontaneous smelting according to this disclosure can only be achieved when the battery is predominantly present in the total feed and when the battery contains a high concentration of Al and / or C.

[0011] Recently, new battery designs using the so-called cell-to-pack technology (CTP) have become more prominent on the market. Batteries using this technology are characterized by a significantly lower Al content. Mathematically, the above formula requires more than 100% of the battery to be added to the feed. Therefore, spontaneous smelting of such Al-poor batteries is impossible.

[0012] Other methods can be used to melt these types of batteries. For example, WO2016023778 uses an electric plasma to provide the additional energy required to melt the battery. The additional energy of course leads to higher costs. Another disadvantage of this method is the higher impurity content in the alloy. This is also observed in WO2011035915.

[0013] A 2-step smelting process for recovering metals from spent Li-ion batteries is known from EP 2 677 048. It teaches the formation of an impure alloy in a first, strong reduction step, which is then purified in a second, oxidation step. The first step is neither energy efficient nor spontaneous.

[0014] The present invention discloses an alternative two-step smelting method for optimizing energy requirements. Even when the Al and C contents of waste batteries are low, the smelting conditions allow for spontaneous smelting in the first step.

[0015] This result is achieved by better utilization of the chemical energy in waste batteries. For this purpose, the process conditions in the first-step smelting are selected so as to oxidize C to CO2. This is completely different from the known method where strong reduction conditions mean that C is only oxidized to CO. Oxidation to CO2 is actually more exothermic and provides the energy required to melt the entire battery, even when it contains components different from those of waste batteries.

[0016] Due to the oxidation conditions in the first step, some Ni and Co will be incorporated into the slag. Therefore, a second-step slag cleaning is required. This second step is only carried out on the slag that preferably remains liquid and only requires a very small amount of energy. Therefore, the total energy requirement for the combination of the two steps is more favorable than that of the single-step smelting method.

[0017] According to a first embodiment, the recovery of valuable metals from a metallurgical feedstock comprising a slag former and a Li-ion battery or its derivatives containing Co, Ni, metallic Al, and C comprises the following steps:

[0018] - Providing a metallurgical furnace equipped with a device for submerged injection of an O2-containing gas;

[0019] - Defining an oxidation level Ox characterizing the oxidation smelting conditions according to the following formula:

[0020] Ox = pCO2 / (pCO + pCO2),

[0021] where 0.1 < Ox < 1, and pCO and pCO2 are the partial pressures of CO and CO2 in contact with the melt;

[0022] - Preparing a metallurgical feedstock comprising a Li-ion battery or its derivatives with a weight fraction Bf according to the following formula:

[0023] 1 > Bf > 0.3 / ((1 + 3.5*Ox)*C + 2.5*Al),

[0024] where Ox is the oxidation level, and Al and C are the weight fractions of metallic Al and C in the battery or its derivatives, respectively;

[0025] - Oxidatively smelting the metallurgical feedstock by injecting an O2-containing gas into the melt to reach the defined oxidation level Ox, thereby obtaining a first alloy mainly composed of Ni and a first slag containing residual Ni and Co;

[0026] - Performing a liquid / liquid separation of the first alloy and the first slag; and

[0027] - performing reduction smelting on the first slag using a heat source and a reducing agent, maintaining a reduction potential, ensuring reduction of Ni and Co, thereby producing a second alloy and a second slag having a Ni content of less than 1% by weight, preferably less than 0.5%, and more preferably less than 0.1%.

[0028] "Slag former" means, for example, one or more of CaO, Al2O3 and SiO2. Other slag formers well known to the skilled person may also be present. The slag former compounds themselves may be added, or they may be obtained in situ from the readily oxidizable metals present in the feed.

[0029] "Li-ion batteries or their derivative products" means: new or waste batteries, scrap batteries, production waste, pre-processed battery materials after crushing or sorting. However, the products will still contain considerable amounts of Co, Ni, metallic Al and C.

[0030] By "substantial portion" of an element is meant more than 50% by weight of the amount of the element present in the metallurgical feed.

[0031] The minimum value of the oxidation level Ox of 0.1 is determined by the need to generate sufficient CO2 to heat and melt the metallurgical feed, since the generation of CO alone is usually insufficient. The upper limit of less than 1 corresponds to avoiding extreme oxidizing conditions, which would prevent a major part of Ni from being incorporated into the alloy during the smelting step. It is assumed here that CO and CO2 are in contact with the melt, thereby ensuring control of the redox conditions.

[0032] The step of defining the oxidation level Ox with a cell fraction Bf requires compliance with the conditions of the formula. Based on the cell composition, it should be verified that the calculated value of Bf is physically feasible, i.e. Bf < 1. Otherwise, higher Ox should be defined until a value less than 1.

[0033] The above operating conditions have been found to be effective for a battery fraction Bf greater than 0.3. Below this value, the battery will likely be unable to provide sufficient energy to allow spontaneous smelting of the total metallurgical charge.

[0034] Clean slag is important from both an economic and ecological point of view. Although the 1 wt% and 0.5 wt% Ni limits are based on economics, 0.1% represents the generally accepted upper limit for the reuse of slag in other useful applications.

[0035] If the criteria of the formula are met, the order of the steps of defining the oxidation level Ox and preparing the metallurgical feed is not important. Thus, starting from a given battery fraction Bf, the minimum oxidation level Ox can be determined. This reverse order is the object of the second embodiment.

[0036] According to the second embodiment, the recovery of valuable metals from a metallurgical feedstock comprising a slag-forming agent and a Li-ion battery or its derivatives containing Co, Ni, metallic Al, and C comprises the following steps:

[0037] - Provide a metallurgical furnace equipped with a device for submerged injection of an O₂-containing gas;

[0038] - Prepare a metallurgical feedstock using a metallurgical feedstock containing a Li-ion battery or its derivatives with a weight fraction Bf;

[0039] - Define an oxidation level Ox characterizing the oxidative smelting conditions according to the following formula:

[0040] Ox = pCO₂ / (pCO + pCO₂)>(((0.3 / Bf - 2.5*Al) / C) – 1) / 3.5, where 0.1 < Ox < 1, pCO and pCO₂ are the partial pressures of CO and CO₂ in contact with the melt, and Al and C are the weight fractions of metallic Al and C in the battery or its derivatives, respectively;

[0041] - Oxidatively smelt the metallurgical feedstock by injecting an O₂-containing gas into the melt to reach the defined oxidation level Ox, thereby obtaining a first alloy mainly composed of Ni and a first slag containing residual Ni and Co;

[0042] - Perform a liquid / liquid separation of the first alloy and the first slag; and

[0043] - Reduce and smelt the first slag using a heat source and a reducing agent, maintaining the reduction potential to ensure the reduction of Co and Ni, thereby producing a second alloy and a second slag with a Ni content of less than 1% by weight, preferably less than 0.5%, more preferably less than 0.1%.

[0044] In this embodiment, the oxidation level Ox is determined after the feedstock has been prepared. It should be verified that the calculated value of Ox that will allow the required oxidation and spontaneous smelting conditions is compatible with the oxidation level Ox < 1.

[0045] It can be shown that the formula for determining Bf starting from Ox is equivalent to the formula for determining Ox starting from Bf.

[0046] Applying the formula of the first embodiment or the second embodiment results in a spontaneous feedstock, which means that the step of oxidative smelting can be carried out by solely utilizing the energy contained in the battery or its derivatives. No additional energy needs to be added, nor fuel, coke, or other carbon sources, nor reactive compounds in the rest of the metallurgical feedstock.

[0047] For example, in actual operation, a small amount of energy may still be provided for various reasons such as compensating for unusually high heat losses of a particular furnace. Such a small amount should preferably be limited to less than 50% of the total energy requirement of the first smelting step, more preferably to less than 10%.

[0048] The type of furnace and the exact operating temperature are not critical, but the temperature should allow sufficient melting of the metallurgical feed to obtain the first alloy and the first slag. Typically, known furnaces operating at temperatures such as 1350°C to 1800°C are suitable for melting feeds containing Li-ion batteries or derived products thereof. Temperatures above 1450°C are preferred to ensure melting of a variety of input materials, while temperatures below 1550°C are preferred to limit energy consumption, as shown in the examples below.

[0049] A further embodiment according to any of the preceding embodiments is characterized by a spontaneous oxidation smelting step, ie using only the energy contained in the battery or its derivatives.

[0050] Liquid / liquid separation of alloy and slag is very common in the metallurgical industry, for example by so-called "tapping" of the liquid phase from a furnace.

[0051] In another embodiment according to any of the preceding embodiments, the slag is maintained in liquid state between the liquid / liquid separation step and the reduction smelting step.

[0052] This ensures that the energy consumed to heat and melt the feed in the first smelting step is conserved to the maximum extent possible. If the slag is allowed to cool and solidify, additional energy will be required to remelt it in the reduction smelting step. This additional energy can usually be tolerated, especially when the amount of the first slag is significantly lower than the amount of the total metallurgical feed.

[0053] In a further embodiment according to any of the preceding embodiments, the O 2 containing gas is enriched air or pure O 2 .

[0054] This embodiment results in less heat losses than when air is used as the O2-containing gas.

[0055] In another embodiment according to any of the preceding embodiments, Ox<0.98, preferably Ox<0.95.

[0056] These conditions correspond to slightly reduced oxidation levels. These may still be sufficient to ensure spontaneous smelting while providing better direct Ni and Co yields in the first alloy.

[0057] In another embodiment according to any of the preceding embodiments, the slag former comprises up to 50% CaO, up to 55% Al2O3 and up to 65% SiO2 by weight.

[0058] Using these guidelines, the skilled person will readily obtain a slag having a viscosity low enough to allow decanting and phase separation at operating temperatures.The slag former may be added itself, or may be generated in situ by oxidation of metals such as Si or Al present in the feed.

[0059] In another embodiment according to any of the preceding embodiments, the method comprises the step of transferring the separated first slag to a second furnace suitable for performing a reduction smelting step, thereby obtaining a second alloy containing Ni and Co and a depleted second slag.

[0060] Therefore, the smelting steps can be carried out batchwise with intermediate tapping of the Ni—Co alloy, or they can be carried out in two different furnaces.

[0061] In another embodiment according to the preceding embodiment, the second melting furnace is an electric furnace.

[0062] When high temperature, strong reducing conditions are required, electric furnaces are indeed appropriate.

[0063] In another embodiment according to any of the preceding embodiments, the method comprises a liquid / liquid separation step of the second alloy and the second slag.

[0064] This second alloy can be further processed by hydrometallurgical methods to separate and purify the metals. This implies a leaching step, which is preferably carried out after atomizing the alloy.

[0065] In a further embodiment according to the preceding embodiment, the method comprises the step of recycling the separated second alloy, preferably in liquid state, to the oxidation smelting metallurgical feed.

[0066] This embodiment produces excellent overall yield of Ni and Co in the first alloy even when the direct yield of the first alloy is low.

[0067] In another embodiment according to any of the preceding embodiments, the method comprises the following steps:

[0068] - atomizing the first alloy; and

[0069] - Dissolving the atomized alloy under acidic conditions to obtain a metal-containing solution suitable for further hydrorefining.

[0070] The oxidation level of the first step is defined by the parameter Ox, i.e. the ratio of pCO2 to (pCO+pCO2). In practice, this level will result in a major portion of the Ni being funneled into the first alloy. The residual Ni will funnel into the first slag, amounting to a concentration greater than 2%, preferably greater than 5%, by weight. This residual slag Ni as well as any slag Co will be recovered in the second alloy.

[0071] According to the above embodiment, the oxidation operating conditions in the first step result in the production of a relatively pure first alloy of Ni and Co, which contains little or no other metals, such as Si, Fe or Mn. These conditions allow at least a portion of the C to be completely oxidized to CO2, thereby generating the necessary energy to melt the feed.

[0072] The reducing operating conditions of the second step ensure complete recovery of Ni and Co in the small amount of the second alloy. This alloy can be further processed, or recycled to the first step, thus ensuring excellent overall recovery of Ni and Co. This second step produces a clean second slag with less than 1% Ni by weight. Not much energy is required, except to compensate for heat losses, especially when the first slag remains liquid.

[0073] Too strong reducing conditions in the second step do not have serious adverse effects, but may result in alloys containing undesirably high amounts of Si and Mn. Si may cause difficulties in downstream processing of the alloy because it is associated with filtration problems in hydrometallurgical processing of the alloy. In the second step, Mn reduction requires additional energy and is therefore undesirable except for the production of a clean slag.

[0074] Guided by the observed properties of Co, Ni and Mn, the skilled artisan will readily be able to control the degree of reduction by adding reducing agents such as coal or natural gas.

[0075] The following examples illustrate the invention.

[0076] Example 1

[0077] The metallurgical feed according to Table 1 was prepared with 500 kg batteries, 80 kg limestone and 20 kg silica. A cylindrical furnace with a diameter of 1 m lined with 200 mm magnesia-chrome bricks was used.

[0078] The feed was continuously added to the furnace at a rate of 500 kg battery / hour while the bath temperature of 1450°C was maintained without the need for additional coke, natural gas or electrical energy. Heat was supplied by using a rate of 77 Nm 3 / h of submerged O2 injection to oxidize Al and C in the cell. These conditions correspond to a CO2 to (CO + CO2) ratio of 0.30.

[0079] After 1 hour, the slag (1.1) was tapped from the furnace while the alloy (1.1) was allowed to cool. This slag amounted to 188 kg and was thrown into a second furnace while it was still liquid. For this second step, an electric furnace was used.

[0080] Table 1: Material balance of the first smelting step

[0081]

[0082] The electric furnace was operated at a temperature of 1500°C and 3.5 kg of coke was added to the slag as a reducing agent. A net power of 30 kWh was supplied to the electric furnace to maintain the bath temperature.

[0083] After 1 hour of reduction and after decantation, the slag (1.2) and alloy (1.2) were tapped from the furnace and allowed to cool. The detailed material balance is provided in Table 2.

[0084] Table 2: Material balance of the second smelting step

[0085]

[0086] Example 2 (Comparative)

[0087] The metallurgical feed according to Table 3 was prepared with 500 kg batteries, 80 kg limestone and 20 kg silica. A cylindrical furnace with a diameter of 1 m lined with 200 mm magnesia-chrome bricks was used.

[0088] The feed was continuously added to the furnace at a rate of 500 kg battery / hour while maintaining a bath temperature of 1450°C without the need for additional coke, natural gas or electrical energy. For high metal yields, 42 Nm 3 / h of O2 to achieve the desired degree of reduction. The conditions applied correspond to a CO2 to (CO+CO2) ratio of 0.0, i.e. essentially only CO and no CO2. 220 kWh of net electricity is required to maintain the desired temperature.

[0089] After 1 hour of reduction and after decantation, the slag (2) and alloy (2) were tapped from the furnace and allowed to cool. Detailed material balances are provided in Table 3.

[0090] Table 3: Material balance for single-step smelting

[0091]

[0092] Comparison of Example 1 and Example 2.

[0093] The first alloy (1.1) produced in Example 1 contains fewer impurities than the alloy (2) from Comparative Example 2. This is particularly the case for C and Mn, where the concentrations in Example 1 are reduced to below the detection limit of 0.1%, compared to 1.2% C and 6.6% Mn. This is also the case for Fe, where the concentration in the first alloy (1.1) is 4%, compared to 6.6% in the alloy (2) according to the Comparative Example. The high purity obtained according to Example 1 will make any hydrometallurgical subsequent processing of the alloy easier and cheaper.

[0094] In addition, the difference between Example 1 and Example 2 is the electric energy required for the two steps. In Example 1, only 30 kWh of energy is required for the reduction process, compared to 220 kWh required in Comparative Example 2. The two-step smelting method of Example 1 only requires 14% of the electric energy according to Comparative Example 2.

[0095] It should be noted that when using larger industrial scale furnaces, the specific electrical energy required in the reduction step will be even lower. Since the volume to area ratio of the furnace will be increased, heat losses will be reduced, providing an even greater advantage.

[0096] Example 3

[0097] The metallurgical feed according to Table 4 was prepared with 500 kg batteries, 80 kg limestone and 20 kg silica, as well as 500 kg slag and 100 kg alloy from, for example, other battery recycling operations. A cylindrical furnace of 1 m diameter lined with 200 mm magnesia-chrome bricks was used.

[0098] Table 4: Material balance of the first smelting step

[0099]

[0100]

[0101] The feed was continuously added to the furnace at a rate of 500 kg battery / hour while the bath temperature of 1450°C was maintained without the need for additional coke, natural gas or electrical energy. Heat was supplied by using an immersed 140 Nm 3 / h of O2 is provided to oxidize Al and C in the cell. These conditions correspond to a ratio of CO2 to (CO + CO2) of 0.85.

[0102] After one hour, the alloy (3.1) formed was tapped from the furnace and allowed to cool. A total of 922 kg of slag (3.1) was tapped and thrown into a second furnace while it was still liquid. For this step, an electric furnace was used.

[0103] The electric furnace was operated at a temperature of 1500°C and 45 kg of coke was added to the slag. After 1 hour of reduction and after decantation, the alloy (3.2) and slag (3.2) were discharged from the furnace and allowed to cool. The detailed material balance is provided in Table 5. A net power of 190 kWh was supplied to the electric furnace to maintain the bath temperature.

[0104] Table 5: Material balance of the second smelting step

[0105]

[0106]

[0107] This example illustrates that the process allows spontaneous operation even when a large amount of the feed contains other components besides the battery. However, a higher degree of oxidation is required: 0.85 in Example 3 compared to 0.30 in Example 1. This produces a first alloy (3.1) that is rich in Ni and poor in Fe. These specifications are favorable. However, the Ni and Co yields of the first smelting step are low. This lower yield can be fully compensated by recycling the alloy from the second smelting step to the first smelting step.

[0108] Example 4

[0109] According to the present invention, Li-ion batteries having the composition shown in Table 6 were smelted in a cylindrical furnace having a diameter of 1 meter and lined with 200 mm magnesia-chrome bricks.

[0110] A metallurgical feed comprising 180 kg limestone and 150 kg silica as flux and 500 kg Li-ion batteries was prepared.

[0111] The mixture was fed continuously to the furnace at a rate of 500 kg of cells / hour and the bath temperature of 1350°C was maintained without the need for coke, natural gas or electrical energy. Energy was provided by oxidation of the Al and C in the cells using submerged O2 injection. For the feeds shown in Table 6, 91 Nm 3 / hour O2. These conditions correspond to a CO2 / (CO+CO2) ratio of 0.45.

[0112] After 1 hour, the phases are discharged from the furnace. The alloy (4.1) is allowed to cool. The slag (4.1) amounts to 400 kg and is thrown into a second furnace while it is still liquid. For this second step, an electric furnace is used.

[0113] Table 6: Material balance of the first smelting step

[0114]

[0115]

[0116] After the first step, the slag was separated and transported to an electric furnace at a temperature of 1500°C, with 10 kg of coke and 400 kg of slag added per hour. After 1 hour of reduction and decantation, the alloy and slag were discharged from the furnace and allowed to cool. The detailed material balance is provided in Table 7.

[0117] Table 7: Material balance of the second smelting step

[0118]

[0119] Example 5

[0120] The metallurgical feed according to Table 8 was prepared with 500 kg Li-ion batteries, 100 kg limestone and 40 kg silica. A cylindrical furnace with a diameter of 1 m lined with 200 mm magnesia-chrome bricks was used.

[0121] The feed was continuously added to the furnace at a rate of 500 kg battery / hour while the bath temperature of 1550°C was maintained without the need for additional coke, natural gas or electrical energy. Heat was supplied by using a rate of 77 Nm 3 / h of submerged O2 injection to oxidize Al and C in the cell. These conditions correspond to a CO2 to (CO + CO2) ratio of 0.30.

[0122] After 1 hour, the slag (5.1) is tapped from the furnace while the alloy (5.1) is allowed to cool. This slag, amounting to 188 kg, is thrown into a second furnace while it is still liquid. For this second step, an electric furnace is used.

[0123] Table 8: Material balance of the first smelting step

[0124]

[0125]

[0126] The electric furnace was operated at a temperature of 1500°C, and 3.5 kg of coke was added to the slag as a reducing agent.

[0127] After 1 hour of reduction and after decantation, the slag (5.2) and alloy (5.2) were tapped from the furnace and allowed to cool. The detailed material balance is provided in Table 9.

[0128] Table 9: Material balance of the second smelting step

[0129]

[0130] in conclusion:

[0131] Examples 4 and 5 show a spontaneous process with different temperatures for the first smelting step.

[0132] Compare the feed battery fraction used to the minimum battery fraction (Bf) required for spontaneous smelting, using the battery composition and oxidation level, Ox = pCO2 / (pCO+pCO2)

[0133] 1>Bf>0.3 / ((1+3.5*Ox)*C)+2.5*Al)

[0134] The cell fraction for Example 4 is 60%, while spontaneous smelting requires 59%. Thus, Example 4 shows the minimum cell fraction required for spontaneous smelting for a given cell composition and a chosen oxidation level. The process is operated at 1350°C, which is sufficient to keep the slag and alloy liquid.

[0135] The cell fraction for Example 5 was 78%, whereas autogenous melting requires 69%. Thus, Example 5 used a cell fraction higher than the minimum required for autogenous melting, and the process was operated at 1550°C.

Claims

1. A method for recovering valuable metals from a metallurgical feed comprising a slag forming agent and a Li-ion battery or a product derived therefrom containing Co, Ni, metallic Al and C, the method comprising the following steps: - Provided with a device for immersion injection containing O 2 Gas equipment for metallurgical furnaces; - The oxidation level Ox, which characterizes oxidation smelting conditions, is defined according to the following formula: Ox=pCO 2 / (pCO+pCO 2 ), where 0.1 < Ox < 1, pCO and pCO 2 are the partial pressures of CO and CO 2 in contact with the melt; - Preparation of a metallurgical feed for Li-ion batteries or derived products thereof comprising a weight fraction Bf according to the following formula: 1>Bf>0.3 / ((1+3.5*Ox)*C)+2.5*Al), Wherein Ox is the oxidation level, Al and C are the weight fractions of metallic Al and C in the battery or its derivative products, respectively; - by injecting into the melt a gas containing O 2 gas to oxidatively smelt the metallurgical feed to a defined oxidation level Ox, thereby obtaining a first alloy containing Ni as a main component and a first slag containing residual Ni and Co; - performing liquid / liquid separation on the first alloy and the first slag; as well as - reducing and smelting the first slag using a heat source and a reducing agent, maintaining a reducing potential to ensure the reduction of Co and Ni, thereby producing a second alloy and a second slag having a Ni content of less than 1% by weight.

2. A method for recovering valuable metals from a metallurgical feed comprising a slag forming agent and a Li-ion battery or a product derived therefrom containing Co, Ni, metallic Al and C, the method comprising the following steps: - Provided with a device for immersion injection containing O 2 Gas equipment for metallurgical furnaces; - using a metallurgical feed material containing a weight fraction Bf of a Li-ion battery or a product derived therefrom to prepare the metallurgical feed material; - The oxidation level Ox, which characterizes oxidation smelting conditions, is defined according to the following formula: Ox = pCO 2 / (pCO + pCO 2 ) > (((0.3 / Bf - 2.5 * Al) / C) – 1) / 3.5, where where 0.1 < Ox < 1, pCO and pCO 2 are the partial pressures of CO and CO in contact with the melt, and Al and C are the weight fractions of metallic Al and C in the cell or its derivatives, respectively; 2 ​ - by injecting into the melt a gas containing O 2 gas to oxidatively smelt the metallurgical feed to a defined oxidation level Ox, thereby obtaining a first alloy containing Ni as a main component and a first slag containing residual Ni and Co; - performing liquid / liquid separation on the first alloy and the first slag; as well as - reducing and smelting the first slag using a heat source and a reducing agent, maintaining a reducing potential to ensure the reduction of Co and Ni, thereby producing a second alloy and a second slag having a Ni content of less than 1% by weight.

3. The method according to claim 1 or 2, wherein the Ni content of the second slag is less than 0.1% by weight.

4. The method of claim 1 or 2, wherein the oxidation smelting step is spontaneous.

5. The method according to claim 1 or 2, wherein the first slag is maintained in a liquid state between the liquid / liquid separation step and the reduction smelting step.

6. The method according to claim 1 or 2, wherein the O-containing 2 The gas is enriched air or pure O 2 .

7. The method according to claim 1 or 2, wherein Ox<0.

98.

8. The method according to claim 1 or 2, wherein the slag former comprises by weight up to 50% CaO, up to 55% Al 2 O 3 and up to 65% SiO 2 .

9. The method according to claim 1 or 2, further comprising the step of transferring the separated first slag to a second furnace suitable for a reduction smelting step, thereby obtaining a second alloy containing Ni and Co and a depleted second slag.

10. The method of claim 9, wherein the second melting furnace is an electric furnace.

11. The method according to claim 1 or 2, further comprising a liquid / liquid separation step of the second alloy and the second slag.

12. The method of claim 11, further comprising the step of recycling the separated second alloy to the autogenous smelting step.

13. The method according to claim 1 or 2, further comprising the following steps: - atomizing the first alloy; and - dissolving the atomized alloy under acidic conditions to obtain a metal-containing solution suitable for further hydrorefining.

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