Method and equipment for recovering metals from black mass

Abstract

A method and plant for recovering metals from black mass comprising the following steps in the following order: (a) providing a black mass containing Li; (b) adding water to the black mass to produce a suspension of the black mass in water; (c) dosing the suspension with ozone as an oxidant while stirring the suspension; (d) filtering and separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of the black mass.

Description

[Technical field]

[0001] The present invention relates to a method for the recovery of metals from lithium-containing black mass and a corresponding installation. [Background technology]

[0002] It is estimated that the world battery production will reach more than 4 TWh by 2030. The resources required for said production, i.e. raw materials such as lithium, graphite, nickel, cobalt and manganese, will therefore reach an estimated amount of more than 10 million tonnes in 2030. The origin of the required raw materials is mainly primary sources from ores, although the share of secondary sources from recycling will increase in the future. Secondary sources can be end-of-life lithium-ion batteries or materials sorted from the manufacturing process and whole batteries.

[0003] Such secondary sources are pre-processed into so-called black mass, which is a mixture of lithium-ion battery scrap and / or scrap materials from the battery manufacturing process that are processed into a fine powder product. Black mass therefore typically contains a mixture of active anode and / or cathode materials of lithium-ion batteries. Furthermore, black mass may contain plastics and / or conductors such as copper and / or aluminum.

[0004] In the prior art several methods are known for recovering the main elements from said black mass. Besides pyrometallurgical processing routes, several hydrometallurgical processing routes are known.

[0005] For example, from EP 3 431 618 A1 a process is known in which lithium ion battery scrap is leached in a subsequent Al removal step followed by a Fe removal step, followed by Ni, Co recovery steps and at the end of the process Li is extracted.

[0006] WO2020 / 212587A1 discloses a process in which lithium is extracted upstream of the Ni and Co recovery process.

[0007] These methods have low extraction rates and / or low selectivity in intermediate products. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a cost-effective process for the recovery of metals from black mass, which allows high selectivity of the recovered metals. [Means for solving the problem]

[0009] The present invention solves this problem by means of the features of the independent claims.

[0010] A process for recovering metals from black mass is proposed, comprising the following steps in the following order: (a) providing a black mass containing Li; - Step (b) of adding water to the black mass to produce a suspension of black mass in water (or a suspension of black mass in water), (c) introducing ozone as an oxidizing agent into the suspension while stirring the suspension; - Step (d) of filtering and separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of the black mass (residue from which Li has been removed), preferably as a solid or a slurry (or step (d) of filtering and separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of the black mass, preferably as a solid or a slurry).

[0011] Black mass in the sense of the present invention is material from discarded lithium-based batteries, in particular lithium-ion batteries, and / or discarded parts thereof, and / or discarded material from the Li-ion battery manufacturing process, such as active cathode material that was not fully incorporated into the battery. The above mentioned raw materials are mechanically processed into a material called black mass, which has a high surface to mass ratio. The typical black color of black mass can be attributed to carbon, in particular graphite or carbon black, which is often used in the active anode material of Li-ion batteries. However, black mass is not limited to the presence of a sufficient fraction of carbon to color the black mass black, since the presence of carbon black in the black mass is not essential.

[0012] Thus, black mass typically contains some or all of the following elements: lithium (Li), carbon (C), cobalt (Co), nickel (Ni), manganese (Mn), iron (Fe), copper (Cu), aluminum (Al), phosphorus (P), and fluorine (F).

[0013] Depending on the source material of the black mass, the fraction of metals recovered in the recycling process may vary widely and may even be zero. Different battery chemistries, known for example as NMC, NCA, LFP, may result in different fractions or even the absence of valuable metals, such as Co, Ni, or Mn. Different components from other elements in the various compositions are therefore possible. However, black mass in the sense of the present invention contains element Li at the start of the metal recovery process. Nevertheless, the source of Li in the black mass may vary, for example it can be chemically bound in the active cathode material and / or it can be metallic Li, in particular in or around the active anode material.

[0014] With regard to step (b), it is further proposed to suspend the black mass in water at a mass ranging from 10 g to 300 g, preferably ranging from 10 g to 250 g, even more preferably ranging from 180 g to 220 g per liter of water, for example 200 g of black mass are suspended in 1 liter of water.

[0015] In step (c) of the proposed method, ozone is dosed as an oxidizing agent into the suspension while stirring the suspension. Preferably, ozone is dissolved in the water of the suspension. Thus, the black mass or at least a fraction of the black mass is oxidized with ozone. Ozone (O3) is known as a strong oxidizing agent. However, the utilization of ozone as an oxidizing agent has some drawbacks as ozone is unstable with respect to carbon dioxide and decomposes quickly. The half-life of ozone is further reduced when dissolved in water and further reduced with increasing temperature, which results in a very low efficiency of the process and may even prevent ozone from reacting in the intended manner when dissolved in water at the precise temperature. The solubility of ozone in water is very low.

[0016] It has been found that by stirring a suspension of black mass in water, mass transfer can be increased to such an extent that the ozone can react with the black mass particles, particularly the surfaces of the black mass particles, in the suspension before the ozone decomposes. Effective use of ozone begins at high stirring speeds and is even more effective at higher stirring speeds, which can result in the production of very high oxidation potentials (>850 mV).

[0017] It is therefore further proposed to apply vigorous stirring or stirring at high stirring speed to the suspension while dosing ozone as oxidant to the suspension. Preferably, by dosing ozone to the suspension while stirring the suspension during step (c), the oxidation / reduction potential (ORP) is >850mV. The ORP can be further increased to >1200mV by very vigorous stirring during step (c). Ozone in this application is an order of magnitude cheaper than oxidants such as persulfates used in alternative recovery processes. Ozone as a strong oxidant with ORP>850mV oxidizes Co and Mn, making it possible to successfully process black mass with different mineralogy and pretreatments without relying on them already being in Co(III) and Mn(IV) state for recovery.

[0018] It is further proposed that turbulence is created within the suspension by stirring the suspension during step (c).

[0019] Preferably, said vigorous agitation or agitation at high agitation speed exceeds a threshold value above which the fraction of ozone that can react with the black mass is greater than the fraction of ozone that prematurely decomposes at the start of step (c).

[0020] In other words, according to the proposed method, a suspension of water and black mass can be leached with ozone, especially in the neutral leach, reaching very high selectivities towards Li.

[0021] Regarding step (d), the filtrate of the proposed method allows the LiOH (lithium hydroxide) dissolved in water to be separated from the remaining material of the black mass, which can then be directed to further process steps.

[0022] The proposed method has a very high selectivity for Li, with a very low fraction of other components than LiOH dissolved in the water. The leaching is truly selective, in advantageous embodiments to no detectable levels, for Ni, Co, and Mn, which are typically present in spent lithium-ion battery materials and therefore in the black mass. High selectivity for Li can be achieved over a wide variety of mineralogical characteristics and pretreatments of the black mass. Furthermore, the proposed method also allows high extraction rates of Li, >90%. The method is therefore very efficient, preferably a batch process, where recycling is possible due to the high selectivity, which is highly advantageous as further explained below. In particular, contamination of the recovered lithium with alkali elements, especially Na and / or K, can be avoided.

[0023] The overall hydrometallurgical removal of Li prevents carbonaceous off-gassing (COx) emissions that occur when graphite, carbon black and / or organic components in the black mass are decomposed and volatilized at high temperatures.

[0024] Li-depleted residues of black mass as solids and / or slurries have Li extracted early in the recovery process. Front-end extraction therefore allows for independent processing of residues containing valuable elements, e.g. Ni, Co, Mn, from other processing options. Furthermore, lithium losses to other products and intermediates due to low washing efficiency or co-precipitation are reduced.

[0025] Additionally, the sodium (Na) requirement is very low due to the use of ozone.

[0026] According to a further development, In step (c), the suspension is heated for 11,000 s -1 Larger, preferably 25000s -1 Larger, preferably 27000s -1 Larger, preferably 29000s -1Larger, e.g. 30000s -1 It is proposed that the mixture be stirred at a shear rate of 11,000 s -1 High shear rates exceeding 12000s -1 , preferably 29000s -1 High shear rates above 11,000s increase mass transfer to a sufficient extent to allow ozone to react with the black mass before it decomposes. -1 Shear rates exceeding 12000s -1 At 29,000 s, a sufficiently high ORP can be achieved to precipitate a suspension of water and black mass with ozone, where higher shear rates can result in even higher ORP. -1 At shear rates above 850 mV, an ORP > 850 mV can be achieved, and higher shear rates can result in higher ORP, for example > 1200 mV.

[0027] For example, the shear rate of a fluid between two parallel plates can be determined by dividing the relative velocity of the two plates by the distance between the plates.

[0028] According to a further development, it is proposed to carry out step (c) for at least 3 h (or 3 hours), preferably for at least 3.5 h (or 3.5 hours), for example for 4 h (or 4 hours).

[0029] The concentration of Li dissolved in the water of the suspension increases with time, up to a maximum extraction rate that can be reached within, for example, 4 hours. In addition to this, the oxidation of Co and Mn also depends on the reaction time, with longer reaction times allowing complete recovery from the solution, for example, 3 hours for Mn and 4 hours for Co. Co and Mo oxides therefore precipitate after being dissolved in the solution. Thus, carrying out step (c) for the times mentioned above allows a very high selectivity of the extraction process.

[0030] It is further proposed to introduce ozone into the suspension in step (c) at a rate of at least 0.1 grams (O3) / hour / gram (black mass), for example 1 gram (O3) / hour / gram (black mass), and / or at a maximum rate of 2 grams (O3) / hour / gram (black mass). The mass flow rate of ozone per hour therefore also depends on the mass of black mass provided containing lithium in suspension. To provide ozone at a constant rate of, for example, 1.5 grams (O3) / hour / gram (black mass), for example, the mass flow rate of ozone must double when the amount of black mass provided doubles.

[0031] There is a lower limit to the dosage of ozone into the suspension in order to obtain a sufficient effect, but the upper limit is primarily for economic reasons, since the proposed agitation increases in a significant manner the effectiveness of the supplied ozone.

[0032] According to a further development, it is proposed that in step (c) the temperature of the suspension is in the range of 70°C to 95°C.

[0033] At temperatures above 70° C., high Li extraction rates of over 90% are obtained, which can be increased to over 95% at 90° C. Therefore, the suspension is preferably heated.

[0034] In an advantageous embodiment, it is proposed that in process step (c), the suspension of black mass in water has a pH value in the range of 6 to 8, preferably in the range of 7 to 8, for example a pH value of 8.

[0035] The extraction of Li in step (c) can in an advantageous embodiment be carried out in a neutral leaching without any pH adjustment, in which case the effect of ozone is ignored, but the process is simplified and therefore more cost-effective. In this case the utilization of sodium in the Li recovery process can be reduced even further, preferably to zero. When ozone is dosed as oxidizing agent into the suspension while stirring the suspension, the suspension has a pH value preferably in the range of 6-8, in particular in the range of 7-8, which allows an extraction rate of Li of more than approximately 70%. Furthermore, the proposed pH range, in particular a pH value of 7-8, has the beneficial effect that Co, Mn and especially Ni do not precipitate out of solution or dissolve in solution, resulting in a very high selectivity of Li extraction as LiOH in water from the black mass, while still having a good extraction rate for Li.

[0036] Thus, the Li-containing filtrate of step (d) may also have a pH value in the range of 6 to 8, in particular 7 to 8, allowing cost-effective further processing of the filtrate.

[0037] In a further development it is proposed to add an acid, preferably sulfuric acid (H2SO4), to the suspension in step (b) and / or step (c) in order to reduce the pH value of the suspension to a pH value in the range from 3.5 to 4.5.

[0038] A pH value below 4.5 further increases the extraction rate of Li compared to embodiments of the method without a decrease in pH value, resulting in Li extraction rates of over 90%, with Li extraction rates of over 95% being possible. A pH value below 3.5 results in excessive loss of Li selectivity.

[0039] Although Co and Mn can be fully recovered by the reaction time proposed above, e.g. 4 h, lowering the pH value in the range of 3.5-4.5 has the side effect that Ni extraction increases with Li extraction for longer times. Thus, the extraction rate of Li increases to very high values, but Ni also dissolves.

[0040] The acid is preferably sulfuric acid (H2SO4), which may have further advantageous effects in later stages of the metal recovery process, for example for the crystallization of Ni-sulfate, however, other acids may also be suitably used depending on the desired end product of the metal recovery process.

[0041] It is further proposed to add a caustic (or caustic / base) after step (c), preferably sodium hydroxide (NaOH) and / or calcium hydroxide (Ca(OH)2) and / or calcium oxide (CaO) to raise the pH value of the suspension before step (d) or the pH value of the filtrate of step (d) to a pH value higher than 6, preferably higher than 9, even more preferably higher than 10.

[0042] In particular, a pH value higher than 9, such as 10, preferably higher than 10, allows for the complete precipitation of Ni(II) as hydroxide from the Li-containing leachate. This is particularly advantageous if the pH value of the suspension is lowered with acid to below 6, or especially below 4.5, in order to maximize the Li extraction rate. Thus, the side effect of dissolved Ni can be reversed, resulting in a very high extraction rate of Li dissolved in water, greater than 90%, such as 95%, while at the same time achieving a very high selectivity or purity of dissolved Li.

[0043] The increase in the pH value of the suspension or filtrate with the caustic agent is preferably carried out at a temperature between 25°C and 70°C.

[0044] Preferably, the pH value of the suspension before filtration is adjusted to pH>9, for example pH=10, more preferably pH>10.

[0045] The filtrate therefore contains Li dissolved as LiOH in water in very high purity. Other elements that may be present in the black mass, such as Ni, Co, Mn, Cu, Al, Fe, remain in the residue.

[0046] Furthermore, said pH adjustment with Ca-containing caustic agents, in particular calcium hydroxide and / or calcium oxide, removes F and / or P from the solution, so that a lower content of F and P in the filtrate is achieved.

[0047] Said pH adjustment with Na-containing caustic, especially sodium hydroxide, leaves F and P in solution, allowing separation of F from the residue and further processing of the residue, which may advantageously prevent accumulation of HF in other downstream processes, e.g., black acid. The required amount of Na added to adjust the pH value to the above values ​​is significantly lower than the solubility limit and does not result in Na contamination of the Li product.

[0048] As a result, the filtrate produced by the proposed method, containing LiOH dissolved in high purity water, and the Li-depleted residue or residue with a significantly reduced Li content, can be processed independently of each other into the desired form of final product of metals recovered from black mass, taking advantage of the high selectivity and extraction rate of Li of the proposed method.

[0049] According to a further development, it is proposed to evaporate at least 20% by volume (vol%) of the filtrate containing LiOH dissolved in water.

[0050] Increasing the extent of evaporation increases the extent of Li recovery in the subsequent Li recovery step. This is due to the high solubility of the Li salt, which prevents complete precipitation, and increased precipitation kinetics and efficiency resulting from the higher Li starting concentration. If vacuum is used, evaporation temperatures are >60°C. If atmospheric or higher pressures are used, temperatures are >100°C.

[0051] According to a further development, it is proposed to precipitate lithium hydroxide (LiOH) from the filtrate containing LiOH dissolved in water, preferably by evaporation and / or crystallization. Thus, lithium hydroxide (LiOH) is preferably extracted from the filtrate containing LiOH dissolved in water, preferably by evaporation and / or crystallization. Preferably, lithium hydroxide (LiOH) can be extracted without further additives.

[0052] According to a further development, it is proposed to add one of the following additives to the filtrate containing LiOH dissolved in water: a source of phosphate, preferably phosphoric acid (H3PO4) and / or sodium phosphate (Na3PO4), as well as the precipitation of lithium phosphate (Li3PO4); and / or A carbonate source, preferably carbonic acid (H2CO3) and / or carbon dioxide (CO2) and / or sodium carbonate (Na2CO3), as well as the precipitation of lithium carbonate (Li2CO3).

[0053] The filtrate containing LiOH dissolved in water is preferably the filtrate of step (d), but may also be the filtrate of a further filtration step. If an additive is added to said filtrate to precipitate Li or Li salts, the filtrate will accordingly become a suspension.

[0054] Depending on the desired lithium salt, appropriate additives can be selected as proposed above so that the recovery process is very flexible with respect to the Li-containing end product. Lithium phosphate is for example suitable for LFP type Li-ion batteries, where it is particularly advantageous due to its low solubility limit compared to lithium carbonate, allowing better recovery rates.

[0055] Temperatures between 50°C and 95°C can be used for precipitation. For lithium phosphate, solubility increases at higher temperatures, but so does precipitation efficiency. Lower temperatures in the range of 50°C to 60°C require less energy and are advantageous when cooling from the evaporation step is not required.

[0056] According to a further development, it is proposed to add a caustic agent, preferably sodium hydroxide (NaOH) and / or calcium hydroxide (Ca(OH)2), to the filtrate containing LiOH dissolved in water. Preferably, the pH value is thereby increased or maintained at or above 9, more preferably 10, even more preferably above 10.

[0057] The addition of the caustic agent may be used to stabilize the pH value when an acid is added to the filtrate containing LiOH dissolved in water to precipitate Li. Furthermore, the caustic agent may be added to increase the pH value to pH>9, e.g. pH10, which reduces the solubility of lithium, especially lithium phosphate (Li3PO4), as the pH value increases to pH10. Thus, higher recovery rates are possible when precipitating Li. The caustic agent may be added to counteract the effect on the pH value of the acid added to precipitate Li, thus maintaining the pH value above 9.

[0058] The precipitated Li salts are preferably filtered off and the Li salts in the residue are then processed into the final product.

[0059] According to a further development, it is proposed to filter the precipitated lithium phosphate (Li3PO4) and / or lithium carbonate (Li2CO3) and / or lithium hydroxide (LiOH) and to recycle the filtrate to the suspension of black mass and water in steps (b) and / or (c).

[0060] Recycling prevents Li loss to the wastewater stream. This is particularly advantageous for lithium carbonate (Li2CO3) and / or lithium hydroxide (LiOH), which have a higher solubility limit than lithium phosphate (Li3PO4). Since solubility losses are minimized by recycling, the selection of products can be independent of solubility limits. Recycling allows higher recoveries, which compensate for the lower recoveries of lithium carbonate and lithium hydroxide, and overall, higher Li recoveries can be achieved. Thus, the selection of the desired lithium end product can be made more freely, so that the directly repurifiable lithium salts lithium carbonate and lithium hydroxide can be selected in a more rational way than lithium phosphate.

[0061] The recycle of the filtrate to the suspension of black mass and water in steps (b) and / or (c) is especially beneficial in combination with the higher pH values ​​maintained in the above process steps, preferably above pH 4.5, more preferably above pH 6, even more preferably above pH 7, e.g. pH 8. Thus, the pH value is preferably not lowered by adding additional acid before Li precipitation. The lower Li extraction rate for said higher pH in step (c) can be compensated by the recycle of the filtrate from Li precipitation to the suspension, due to the high Li selectivity of the proposed method involving ozone and agitation. Thus, less sodium and acid are required to recover Li from the black mass or spent battery materials, reducing the environmental impact of further treating the process wastewater.

[0062] According to a further development, it is proposed to periodically bleed the recycled filtrate.

[0063] Said bleeding is particularly useful for bleeding Na and F. The use of sodium hydroxide (NaOH) as the Na-bearing caustic added to the Li-bearing filtrate as described above results in a high concentration of recycled Na in the solution, which may be bled periodically to prevent possible crystallization of Na2SO4, which may result in a lower overall Li recovery.

[0064] Using calcium hydroxide as the Ca-containing caustic, the Ca, F and P from the Li-depleted residue of step (d) can be used in further processing steps.

[0065] The high Li extraction rates at the front end of the proposed process for metal recovery enable different downstream processes that may otherwise be inefficient or impossible.

[0066] According to a further development, it is proposed that the lithium-depleted residue of step (d) is leached in an acid leaching step (e) in which at least one acid, preferably sulfuric acid (H2SO4), and / or recycled acid, in particular recycled black acid, is added and the pH value is lowered to below pH 3. Preferably, a reducing agent, preferably sulfur dioxide (SO2), is added to the acid leaching step (e).

[0067] According to a further development, it is proposed to add a calcium source, preferably calcium hydroxide (Ca(OH)2) and / or calcium oxide (CaO) and / or calcium carbonate (CaCO3), to the leachate and / or suspension in step (e) and to filter the suspension in step (f).

[0068] According to a further development, it is proposed in step (g) to introduce ozone as an oxidizing agent into the filtrate of step (f) while stirring, to maintain the pH value in the range from 2 to 4, preferably at a pH value of 3, and to filter the suspension obtained.

[0069] Recoveries of >95% for Co, >99% for Mn and <3% for Ni were obtained. As a result of the filtration in step (g), Co and / or Mn are recovered in the residue and Ni is extracted in the filtrate of step (g).

[0070] According to a further development, in step (h), it is proposed to add sulfuric acid (H2SO4) to the filtrate of step (g) to increase the sulfuric acid (H2SO4) concentration to at least 500 g / l and to crystallize Ni sulfate.

[0071] The crystallized Ni sulfate is preferably separated by filtration. The filtered solution or filtrate is called black acid.

[0072] Preferably, the filtered solution from step (h), known as black acid, is recycled to the acid leaching step (e).

[0073] Furthermore, a facility for carrying out the process according to any one of claims 1 to 20 is proposed. [Brief description of the drawings]

[0074] In the following, the invention will be explained on the basis of preferred embodiments with reference to the drawings. [Figure 1] Figure 1 shows the degree of extraction EE (%) of Li, Ni, Co and Mn versus pH value. [Diagram 2] Figure 2 shows the time course (min) of the solution concentration SC (g / l) of Li, Ni, Co, and Mn. [Diagram 3] FIG. 3 shows the Ni recovery rate (%) versus pH value, and [Figure 4] FIG. 4 shows the lithium solution concentration Li SC (g / l) after lithium phosphate precipitation versus pH value.

[0075] In a first preferred embodiment of the process for recovering metals, the process steps for separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of black mass are described in the following examples.

[0076] In step (a) black mass is provided as a raw material containing metals, in particular Li. The black mass is made from Li-ion battery scrap that has been converted into a powder. The mineralogical properties of the black mass may vary depending on the starting material, or scrap material. As an example, two mineralogical properties of black mass are as follows: Black Mass #1: C1;Co 0.2069 Li 0.756 Ni 0.793 O2;Ni1O1;Al2O3; Black Mass #2: C1;Fe1Ni3;Mn1O1;Cu 0.8 Fe 0.2 ;C 0.5 H 8.9 FeO 8.95 ;Al1Li1O2;Cu1O1;

[0077] The black mass used in this example may have an elemental composition according to Table 1: TIFF0007657367000001.tif30169

[0078] The balance may include elements such as C, H, O, Fe, Al, Cu, etc.

[0079] The black mass is suspended in water in step (b), 50 g of black mass having the composition in Table 1 are suspended in 1 liter of water.

[0080] The suspension is heated to 70°C, ozone (O3) is dosed to the suspension at 0.9 l / min, and the suspension is stirred while the ozone is dosed in step (c). The suspension is stirred vigorously for about 29,000 s. -1 Create a shear rate in the suspension. The pH value settles at pH 8. After 4 hours, stop the reaction at 70 °C.

[0081] In the next step (d), the suspension is filtered, the filtrate containing about 70% of the lithium of the initial black mass, which is dissolved in water. The residue therefore contains about 30% of the lithium of the initial black mass, which further contains substantially all of Ni, Co, Mn, so that high purity Li in solution is available for further processing of the solution. This is also shown in FIG. 1, which shows the extraction extent EE of Li, Ni, Co and Mn depending on the pH value. Therein, a high selectivity towards Li of the leaching process with ozone at high temperature of a suspension of black mass in water is shown for pH values ​​above 6, where stirring the suspension at very high shear rates while feeding ozone to the suspension is essential to achieve the intended oxidation of the black mass with ozone.

[0082] In a second preferred embodiment of the method for recovering metals, the process steps for separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of the black mass are described in the examples below.

[0083] Deviating from the first embodiment, after the start of step (c), acid is added to the suspension of black mass and water, i.e. ozone is dosed to the suspension while it is being stirred. In this preferred embodiment, 50% sulfuric acid (H2SO4) is added to reduce the pH value to 4. The reaction is then continued for 4 hours.

[0084] Figure 2 shows the solution concentration SC (g / l) of Li, Ni, Co and Mn in minutes (min) over time and indicates that the degree of oxidation of Co and Mn depends on the reaction time. Co and Mn are oxidized to Co(III)- and Mn(IV)-oxides, thus allowing Co and Mn to be completely recovered from the solution over a longer period of time. Li and Ni extraction increases with longer periods at the above pH values.

[0085] Thus, the extraction rate of Li can be increased to over 90% compared to about 70% in the first embodiment where no additional acid is provided to the suspension, again in accordance with the data in Figure 1. Thus, in the second embodiment, a higher extraction rate of Li is achieved while giving up some of the selectivity of the process where Ni is partly extracted as Ni(II).

[0086] After the reaction, or step (c), in this advantageous embodiment, 12 ml of calcium oxide (CaO) suspension is added to 500 ml of the above suspension at 50° C. and the pH value is increased to 10. The reaction is complete after 1.5 hours. The Ni in the solution precipitates and the extent of precipitated Ni RE across pH values ​​is shown in FIG. 3. Thus, increasing the pH value up to pH 10 results in complete recovery of the dissolved Ni.

[0087] Other caustics such as sodium hydroxide (NaOH) and / or calcium hydroxide (Ca(OH)2) may also be used. Typical solution concentrations after pH adjustment to pH 10 are shown in Table 2 for different caustics. TIFF0007657367000002.tif63169

[0088] As in the first embodiment, in a next step (d), the suspension is filtered, the filtrate in the second embodiment containing more than 90% of the lithium of the initial black mass, which lithium dissolves in water, and the residue is therefore further depleted in Li and contains less than 10% of the lithium of the initial black mass.

[0089] As shown in Table 2, the method has a very high extraction rate and high selectivity for Li, and at the same time, the method is very cost-effective.

[0090] In a third preferred embodiment, a further treatment to recover lithium from the filtrate containing LiOH dissolved in water of the first or second embodiment or any embodiment of the method according to the invention is described.

[0091] The filtrate containing LiOH dissolved in water is evaporated to concentrate lithium, and the extent of evaporation is >20 vol%. Increasing the extent of evaporation increases the amount of Li recovered in the following Li recovery process.

[0092] For example, the treatment following the second embodiment may be as follows: A Li-containing solution, for example 300 ml, is heated to 95° C., where the pH is 10. The starting solution concentrations are shown in Table 3. TIFF0007657367000003.tif26169

[0093] Phosphoric acid, H3PO4, is added to form Li3PO4, where NaOH and / or in an alternative embodiment Ca(OH)2 are added to maintain a pH >10. Maintaining a pH >10 increases lithium recovery because Li3PO4 solubility in solution decreases as the pH increases to pH 10. The Li remaining in solution after Li recovery by Li-phosphate dissolution, Li SC, is shown in Figure 4.

[0094] Temperatures between 50°C and 95°C can be used for deposition. Li3PO4 solubility increases at higher temperatures, but so does deposition efficiency. Lower temperatures around 50°C are preferred as less energy is required and no cooling from the evaporation step is required.

[0095] In the above embodiment, 1.29 ml of 85% H3PO4 is added to the solution. The pH is maintained at 10 by adding 55.5 ml of 1 M NaOH. The reaction at 95°C is complete after 1 hour. The filtrate concentration is shown in Table 4. The Li precipitate composition has 19.57 wt% Li.

[0096] The Li-containing filtrate after Li recovery is recycled as make-up solution to the black mass and water suspension of step (b) and / or to the leachate, particularly the neutral leachate, of step (c). Recycling prevents Li loss to the waste stream. Periodic bleeding of the filtrate is used when Na-based caustics are used, the bleeding being to limit Na and F. Recycling of the Li-recovery filtrate is possible due to the low impurities in the filtrate, and the filtrate analysis is shown in Table 4. TIFF0007657367000004.tif26169

[0097] This recycle is particularly advantageous in combination with the first embodiment where the pH value is not lowered by the added acid, so that less caustic is needed to raise the pH value of the solution to re-precipitate Ni and achieve higher pH values ​​to increase Li recovery. Furthermore, even lower pH values ​​can be used, since the Li remaining in solution, Li SC, is not lost to the waste stream at pH values ​​below 10 (see FIG. 4).

[0098] Recovery of remaining elements from Li-depleted black mass or residues, including, for example, Ni, Co, and / or Mn, is described in the following advantageous embodiments.

[0099] In the first step, the residue from the first or second embodiment or from the proposed method in general is leached with sulfuric acid (H2SO4) and SO2 (gaseous) in an acid leaching step. The temperature is 70°C, ORP<200mV. The pH is controlled to <2 by recycled acid or black acid (see process step (h)) and / or sulfuric acid addition. All remaining metals are leached from the black mass. The graphite remains in the residue. The suspension is preferably not filtered after leaching.

[0100] In the second step, fluorine (F) is precipitated from the acid leaching process by adding a Ca source, e.g., calcium hydroxide (Ca(OH)2), calcium oxide (CaO) and / or calcium carbonate (CaCO3). HF and F ions precipitate with calcium as CaF2. After precipitation, the suspension is filtered.

[0101] In the third step, Co and Mn are recovered. Therefore, ozone (O3) is added to the F-precipitation filtrate. The pH is controlled at pH 3 by adding calcium hydroxide (Ca(OH)2). Co and Mn precipitate out of the solution. The recovery is >95% Co, >99% Mn, <3% Ni.

[0102] In the fourth step of recovery of the remaining elements from the Li-depleted black mass or residue, sulfuric acid (H2SO4) and recycled acid or black acid are added to the Co, Mn recovery filtrate at a concentration of 150-400 g / L H2SO4. The evaporation temperature is >100°C. The evaporation extent reaches a H2SO4 concentration of 800 g / L. Ni, Cu and Al crystallize out of solution and are recovered. The filtered solution is called black acid and is preferably recycled to the acid leaching step.

[0103] In general, the proposed methods for the recovery of metals from black mass are possible hydrometallurgical.

[0104] The following is an invention described at the beginning of the present application. <Claim 1> (a) providing a black mass containing Li; - (b) adding water to said black mass to produce a suspension of black mass in water; (c) introducing ozone as an oxidizing agent into the suspension while stirring the suspension; and - Step (d) of filtering and separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of said black mass. 1. A method for recovering metals from black mass, comprising the steps of: <Claim 2> In step (c), the suspension is stirred for 11,000 s in the suspension. -1 2. The method according to claim 1, characterized in that the stirring is carried out at a higher shear rate. <Claim 3> In step (c), the suspension is stirred for 25,000 s in the suspension. -1 3. The method according to claim 1 or 2, characterized in that the stirring is carried out at a higher shear rate. <Claim 4> The method according to any one of claims 1 to 3, characterized in that step (c) is carried out for at least 3 h. <Claim 5> 5. A method according to claim 1, characterized in that in step (c), ozone is administered to the suspension at a rate of at least 0.1 grams (O3) / hour / gram (black mass) and / or at a maximum rate of 2 grams (O3) / hour / gram (black mass). <Claim 6> The method according to any one of claims 1 to 5, characterized in that in step (c), the temperature of the suspension is in the range of 70°C to 95°C. <Claim 7> 7. The method according to claim 1, characterized in that, in step (c), the suspension of black mass in water has a pH value ranging from 6 to 8. <Claim 8> 8. The method according to claim 1 , characterized in that it comprises in step (b) and / or step (c) adding an acid to the suspension to reduce the pH value of the suspension to a pH value in the range from 3.5 to 4.5. <Claim 9> - after step (c), adding a caustic agent, and 9. The method according to claim 8, characterized in that it comprises increasing the pH value of the suspension before step (d) or increasing the pH value of the filtrate of step (d) to a pH value higher than 6. <Claim 10> 10. The method according to claim 1, characterized in that it comprises a step of evaporating at least 20 vol.% of the filtrate comprising LiOH dissolved in water. <Claim 11> 11. The method according to claim 1, characterized in that it comprises a step of precipitating lithium hydroxide (LiOH) from the filtrate comprising LiOH dissolved in water, preferably by evaporation and / or crystallization. <Claim 12> 11. The method according to claim 1, characterized in that one of the following additives is added to the filtrate containing LiOH dissolved in water: a source of phosphate, preferably phosphoric acid (H3PO4) and / or sodium phosphate (Na3PO4), and also precipitated lithium phosphate (Li3PO4), and / or A carbonate source, preferably carbonic acid (H2CO3) and / or carbon dioxide (CO2) and / or sodium carbonate (Na2CO3), as well as precipitated lithium carbonate (Li2CO3). <Claim 13> 13. The method according to claim 11 or 12, characterized in that a caustic agent, preferably sodium hydroxide (NaOH) and / or calcium hydroxide (Ca(OH)2), is added to the filtrate containing LiOH dissolved in water. <Claim 14> A method according to any one of claims 11 to 13, characterized in that the precipitated lithium phosphate (Li3PO4) and / or lithium carbonate (Li2CO3) and / or lithium hydroxide (LiOH) are filtered off and the filtrate is recycled back to the suspension of black mass and water in step (b) and / or (c). <Claim 15> 15. The method according to claim 14, characterized in that the recycled filtrate is periodically bled. <Claim 16> 16. The method according to any one of the preceding claims, wherein the Li-depleted residue of step (d) is leached in an acid leaching step (e) in which at least one acid, preferably sulfuric acid (H2SO4), and / or recycled acid is added to reduce the pH value to below pH 3. <Claim 17> 17. A process according to claim 16, characterized in that in the acid leaching step (e) a reducing agent is added, preferably sulfur dioxide (SO2). <Claim 18> 18. The method according to claim 16 or 17, characterized in that a source of calcium, preferably calcium hydroxide (Ca(OH)2) and / or calcium oxide (CaO) and / or calcium carbonate (CaCO3), is added to the leachate and / or suspension of step (e) and in step (f) the suspension is filtered. <Claim 19> - in step (g), introducing ozone as an oxidizing agent into the filtrate of step (f) while stirring; and - maintaining the pH value in the range of 2 to 4; and 19. The method according to claim 18, characterized in that the suspension obtained is filtered. <Claim 20> - in step (h), adding sulfuric acid (H2SO4) to the filtrate of step (g), and 20. The method according to claim 19, characterized in that the concentration of sulfuric acid (H2SO4) is increased to at least 500 g / l to crystallize Ni sulfate. <Claim 21> Equipment for carrying out the method according to any one of claims 1 to 20.

Claims

1. (a) providing a black mass containing Li; - (b) adding water to said black mass to produce a suspension of black mass in water; - a step (c) of introducing ozone as an oxidizing agent into said suspension while stirring said suspension; and - Step (d) of filtering and separating the filtrate containing LiOH dissolved in water from the Li-depleted residue of said black mass. in the above order, In step (c), the suspension is stirred for 11,000 s in the suspension. －１ The method is characterized in that the mixture is stirred at a higher shear rate. A method for recovering metals from black mass.

2. In step (c), the suspension is stirred for 25,000 s in the suspension. －１ 2. The method of claim 1, characterized in that the stirring is carried out at a higher shear rate.

3. 3. The method according to claim 1 or 2, characterized in that step (c) is carried out for at least 3 h.

4. In step (c), at least 0.1 grams (O ３ ) / hour / gram (black mass) and / or at a rate of 2 grams (O ３ 4. The method according to claim 1, characterized in that the ozone is dosed into the suspension at a maximum rate of 1000 s / hour / gram of black mass.

5. A method according to any one of claims 1 to 4, characterized in that in step (c), the temperature of the suspension ranges from 70°C to 95°C.

6. A method according to any one of claims 1 to 5, characterized in that, in step (c), said suspension of black mass in water has a pH value ranging from 6 to 8.

7. 6. The method according to claim 1, further comprising the step of adding an acid to the suspension in step (b) and / or step (c) to reduce the pH value of the suspension to a pH value in the range from 3.5 to 4.

5.

8. - after step (c), adding a caustic agent, and 8. The method according to claim 7, characterized in that it comprises a step of increasing the pH value of the suspension prior to step (d) or of increasing the pH value of the filtrate of step (d) to a pH value higher than 6.

9. A method according to any one of claims 1 to 8, characterized in that it comprises a step of evaporating at least 20 vol.% of the filtrate comprising LiOH dissolved in water.

10. The method according to any one of claims 1 to 6 or 8 or according to claim 9 dependent thereon, characterized in that it comprises a step of precipitating lithium hydroxide (LiOH) from the filtrate comprising LiOH dissolved in water by evaporation and / or crystallization.

11. - the filtrate containing LiOH dissolved in water, - A source of phosphoric acid, as well as precipitated lithium phosphate (Li ３ P.O. ４ ), and / or - Carbonate source, as well as precipitated lithium carbonate (Li ２ CO ３ ) The method according to any one of claims 1 to 9, characterized in that the additive is added.

12. A method according to claim 10 or 11, characterized in that a caustic agent is added to the filtrate comprising LiOH dissolved in water.

13. - Precipitated lithium phosphate (Li ３ P.O. ４ ) and / or lithium carbonate (Li ２ CO ３ 13. The process according to any one of claims 10 to 12, characterized in that the black mass and / or lithium hydroxide (LiOH) are filtered off and the filtrate is recycled back to the suspension of black mass and water in step (b) and / or (c).

14. A process according to claim 13, characterized in that the recycled filtrate is periodically bled.

15. 15. The method according to any one of the preceding claims, characterized in that the Li-depleted residue of step (d) is leached in an acid leaching step (e) in which at least one acid and / or recycled acid is added to reduce the pH value to below pH 3.

16. A process according to claim 15, characterized in that in the acid leaching step (e) a reducing agent is added.

17. 17. The method according to claim 15 or 16, characterized in that a source of calcium is added to the leachate and / or suspension of step (e) and in step (f) the suspension is filtered.

18. - in step (g), introducing ozone as an oxidizing agent into the filtrate of step (f) while stirring; and - maintaining the pH value in the range of 2 to 4; and The process according to claim 17, characterized in that the suspension obtained is filtered.

19. In step (h), sulfuric acid (H ２ SO ４ to the filtrate of step (g); and -Sulfuric acid (H ２ SO ４ 19. The method according to claim 18, characterized in that the concentration of Ni sulfate is increased to at least 500 g / l to crystallize Ni sulfate.

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