FR2812973A1 - PROCESS FOR HYDROMETALLURGICAL TREATMENT OF USED BATTERIES TO RECOVER RECOVERABLE BY-PRODUCTS, SUCH AS NICKEL AND COBALT - Google Patents

Abstract

A method for the hydrometallurgical treatment of spent batteries comprises successive stages consisting of: (i) simultaneously grinding, in a wet medium, the batteries, (ii) wet screening to separate a fine part containing the nickel, the cobalt and other elements, (iii) subjecting this fine part to a chemical attack by an oxidising acid, (iv) subjecting the final solution from the chemical attack to a compounding operation to form a nickel and cobalt compounds and (v) precipitating of the nickel and cobalt from their respective compounds.

Description

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La présente invention concerne un procédé de traitement hydrométallurgique d'accumulateurs usagés pour en séparer les différents constituants et en récupérer des sous-produits valorisables, tels que le nickel et le cobalt. Le développement des téléphones et ordinateurs portables et les recherches sur les véhicules électriques ont conduit au développement de nouvelles générations d'accumulateurs. Parmi ceux-ci, les accumulateurs du type Nickel Métal Hydrure (en abrégé NiMH) et du type Lithium ions (en abrégé Li ion) sont les plus répandus et les plus prometteurs. Les accumulateurs du type NiMH sont composés d'une cathode d'hydroxyde de nickel, d'une solution de potasse comme électrolyte et d'une anode d'hydrures métalliques. Les métaux des hydrures sont des alliages complexes de nickel, cobalt, terres rares, avec des catalyseurs (Cr, Mo, W, Ni et Co). Les séparateurs des accumulateurs sont en polyamide et leur carcasse est fabriquée en acier inoxydable. La composition chimique d'un accumulateur du type R6 est la suivante : de 35 à 40% de Ni, de 2 à 5% de Co, de 0 à 5 % de Ti, de 0 à 7 % de V, de 0 à 10% de terres rares, de 0 à 2 % de Mn, de 20 à 25% de Fe, de 4 à 5 % de matière plastique et de 18 à 20% d'électrolyte, les pourcentages étant en poids. Les accumulateurs du type Li ion comportent une cathode de LiCo0zet Li Ni02 et@de graphite, une solution de sels de lithium (perchlorate) et de carbonate de propylène en tant qu'électrolyte et une anode de lithium métal. Ce type d'accumulateur présente des dangers d'inflammabilité par suite de la présence de lithium métal; par contre la

The present invention relates to a process for the hydrometallurgical treatment of used accumulators in order to separate the various constituents therefrom and recover recoverable by-products, such as nickel and cobalt. The development of telephones and laptops and research on electric vehicles have led to the development of new generations of accumulators. Among these, the Nickel Metal Hydride type (abbreviated NiMH) and the Lithium ion type (abbreviated Li ion) are the most widespread and the most promising. NiMH type accumulators are composed of a nickel hydroxide cathode, a potassium hydroxide solution as electrolyte and a metal hydride anode. Hydride metals are complex alloys of nickel, cobalt, rare earths, with catalysts (Cr, Mo, W, Ni and Co). The separators of the accumulators are made of polyamide and their casing is made of stainless steel. The chemical composition of an R6 type battery is as follows: from 35 to 40% of Ni, from 2 to 5% of Co, from 0 to 5% of Ti, from 0 to 7% of V, from 0 to 10 % of rare earths, from 0 to 2% of Mn, from 20 to 25% of Fe, from 4 to 5% of plastic material and from 18 to 20% of electrolyte, the percentages being by weight. Li ion type batteries include a LiCo0zet Li Ni02 and @ graphite cathode, a solution of lithium salts (perchlorate) and propylene carbonate as electrolyte and a lithium metal anode. This type of accumulator presents flammability hazards due to the presence of lithium metal; on the other hand

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 high voltage of the oxide pairs of Ni, Co / Li leads to a high energy capacity. The chemical composition of a Li ion type battery is as follows: from 20 to 25 of Li, from 7 to 10% of Co, from 20 to 25% of Fe, from 15 to 20 of plastic material and from 18 to 20 % electrolyte.

Currently, the disposal of used accumulators is entrusted by their manufacturers to specialists in one of the main metals, nickel and cobalt, constituting the accumulators. These specialists are only interested in accumulators containing their base metal, nickel or cobalt. Used batteries are also often found in landfills and in the future it is expected that all batteries will need to be recycled.

The object of the present invention is to provide a process for the hydrometallurgical treatment of used accumulators which does not require sorting upstream between the different types of accumulators and making it possible to treat, during a single and same succession of mechanical and chemical operations , all types of accumulators possible by separately recovering the main recoverable metals, that is to say nickel and cobalt.

accumulateurs de différents types, notamment des accumulateurs du type NiMH et Li ion, à effectuer un criblage humide pour séparer, d'une part, une partie fine contenant le nickel, le cobalt et d'autres éléments tels To this end, this process of hydrometallurgical treatment of used accumulators to separate the different constituents and recover valuable by-products, such as nickel and cobalt, is characterized in that it comprises the successive stages consisting in grinding simultaneously, in a humid environment,

accumulators of various types, in particular accumulators of the NiMH and Li ion type, to be carried out with a wet screening in order to separate, on the one hand, a fine part containing nickel, cobalt and other elements such

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 than iron, rare earths and / or lithium, and, on the other hand, sterile materials, to subject the fine part to chemical attack by an oxidizing acid, by forming a final attack solution, to subject the final etching solution to a complexation of nickel and cobalt so as to form stable and very soluble nickel and cobalt complexes, and to cause precipitation of nickel and cobalt from their respective complexes.

The first step of the process according to the invention is a step of grinding the accumulators in a humid environment, for example in water. Grinding under a stream of water prevents overheating and the risk of explosion linked to lithium metal. Indeed, lithium reacts very quickly with water to provide a lithium hydroxide and the exothermic nature of the reaction is limited by the cooling linked to the stream of water.

The next stage of the process is a wet screening carried out with an 8 mm grid mesh, the ground material being screened with a 3.5 mm mesh. The part whose pieces have a dimension greater than the mesh of the screen consists essentially of steel and scrap, plastic, ferro-nickel, paper. This part, the particle size of which is greater than the mesh, contains magnetic and non-magnetic products and a separation between them is carried out taking account of this physical property.

In the description which follows, all the percentages of the constituents indicated are percentages by weight. In addition only are indicated,

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 in the various compositions, their main constituents.

The composition of the fine fraction or in solution which is obtained after the screening step is generally as follows; relative to the initial mass of each component of the ground material Ni = 40 to 45% Co = 90 to 95% Li = 99% Rare earth = 95 to 99% Fe = 1 to 2% In the case of NiMH type accumulators, the fine fraction represents 30 to 40% of the initial mass of the ground material and generally has the following composition Ni = 40 to 45% Co = 8 to 10% Rare earths = 10 to 20% (variable depending on the origin of the accumulators) Fe = 1 at 2% In the case of accumulators of the Li ion type, the fine fraction also represents from 30 to 40% of the initial mass of the ground material and has the following composition Co = 20 to 30% Fe = 1 to 2% The third stage of process according to the present invention is a chemical attack in an acid medium in order to obtain soluble cobalt and nickel salts. This chemical attack is carried out with an oxidizing acid, such as nitric acid, sulfuric acid, etc. In a non-limiting embodiment of the method according to the invention, sulfuric acid is used at 20 % with a solid concentration of 100 to 200 g / 1, hot

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 (at a temperature of 40 to 65 C) for a period of time of the order of two hours. The solution obtained at the end of the chemical attack has a composition close to the following Ni = 15 to 30 g / 1 Co = 10 to 15 g / 1 Rare earth = 4 to 10 g / 1 Li = 10 to 15 g / l Fe = 200 to 500 mg / 1 pH = 0.5 to 1 This solution must be purified (Fe, Li and rare earths) preferably before the recovery of nickel and cobalt.

To obtain the precipitation of iron, an alkalization with lime is carried out, with a pH of the order of 4 to 5. The precipitation of CaSO 4 facilitates filtration.

Co` + 6NH4+ -@ [Co(NH3)d++ + 6H+ Ni++ + 6NH4+ [Ni(NH3)r,]'+ + 6H+ On sépare ensuite le nickel et le cobalt, d'une part, des terres rares et du lithium, d'autre part, par une alcalinisation à la soude et une carbonatation au gaz carbonique, avec un pH de 6 à 6, 5, ce qui entraîne la précipitation de carbonates de terres rares et de lithium. Then, because nickel and cobalt have the property of forming hexacoordinated complexes in the bivalent state, very soluble, one proceeds to a complexation of nickel and cobalt by adding to the solution, for example, chloride d ' excess ammonium, with a pH of 4 to 5. This operation leads to the formation of stable complexes and to an acidification of the solution

Co` + 6NH4 + - @ [Co (NH3) d ++ + 6H + Ni ++ + 6NH4 + [Ni (NH3) r,] '+ + 6H + Then separate nickel and cobalt, on the one hand, rare earths and lithium, on the other hand, by alkalization with sodium hydroxide and carbonation with carbon dioxide, with a pH of 6 to 6.5, which leads to the precipitation of rare earth carbonates and lithium.

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 The recovery of nickel and cobalt is practically total (greater than 996).

2 [Co (NH3) 6]++ + CIO- + H20 2[Co (NH3) 6]+++ + CI- + 20H- 2[Ni (NH3) 6)++ + CIO- + 2H20 Ni203@ + CI- + 12NH3T + 4H+ Le précipité noir obtenu, facilement filtrable, est, en réalité, un mélange d'oxyde salin et d'hydroxyde de nickel trivalent. The next step consists in separating the nickel from the cobalt and this separation is carried out by oxidation with bleach at alkaline pH (greater than 12); alkalinization is ensured with soda.

2 [Co (NH3) 6] ++ + CIO- + H20 2 [Co (NH3) 6] +++ + CI- + 20H- 2 [Ni (NH3) 6) ++ + CIO- + 2H20 Ni203 @ + CI- + 12NH3T + 4H + The black precipitate obtained, easily filterable, is, in reality, a mixture of saline oxide and trivalent nickel hydroxide.

The nickel recovery rate is 99% compared to the nickel contained in the starting solution; cobalt entrainments are weak, if washing with ammonia water is carried out on the nickel cake.

Finally, the last step of the process according to the present invention is that of the recovery of cobalt. This recovery is obtained by acidification to a pH of about 4 and sulfurization by adding sodium sulfide, leading to the precipitation of cobalt sulfides. The recovery rate of cobalt is 97 to 98%.

Some examples of various types of accumulator treatments are given below.

Example 1: NiMH accumulator model 3,6V.

50 kilograms of accumulators are milled in a stream of water, with an 8-millimeter grid mesh, and then the ground material is sieved with a 3.5-millimeter mesh. The part of granulometry greater than the mesh of the screen represents 70% by weight of the starting product and it consists of 34% of steel and

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ferraille, 11% de matière plastique, de 29% de ferro-nickel et de 27% de papier. La partie de granulométrie inférieure à la maille du crible représente 30% du produit de départ. Elle comprend, entre autres, 42% de nickel et 6% de cobalt. On effectue ensuite une lixiviation en milieu acide puis on ajoute de la soude, de l'hypochlorite de sodium et du chlorure d'ammonium. Le cobalt forme alors le complexe Co (NH4) 63+ soluble, (la constante de complexe est 7, 3) . Le nickel précipite sous forme de Ni304 noir qui est facilement filtré. On récupère 99% de nickel. Par ajout de sulfure de sodium, le sulfure de cobalt précipite. On obtient 97% du cobalt contenu. Exemple 2 : Accumulateur LiMH modèle 6V. Comme dans l'exemple 1, on broie 50 kilogrammes d'accumulateurs en milieu humide et on effectue ensuite un criblage. La partie de granulométrie supérieure à la maille du crible représente 66% du produit de départ. Elle est constituée de 49% d'acier et de ferraille 30% de plastiques 6 % de ferro-nickel 14% de papier La partie de granulométrie inférieure à la maille représente 34% du produit de départ. Elle comprend, entre autres, 44% 'de nickel et 6% de cobalt. On effectue ensuite une lixiviation acide puis on ajoute de la soude jusqu'à l'obtention d'un pH neutre, de l'hypochlorite de sodium pour oxyder le nickel et du chlorure d'ammonium pour complexer le cobalt. Dans ce milieu, l'hydroxyde de nickel

scrap, 11% plastic, 29% ferro-nickel and 27% paper. The part of particle size smaller than the mesh of the screen represents 30% of the starting product. It includes, among other things, 42% nickel and 6% cobalt. An acidic leaching is then carried out and then sodium hydroxide, sodium hypochlorite and ammonium chloride are added. Cobalt then forms the soluble Co (NH4) 63+ complex, (the complex constant is 7.3). The nickel precipitates in the form of black Ni304 which is easily filtered. 99% of nickel is recovered. By adding sodium sulfide, the cobalt sulfide precipitates. 97% of the cobalt contained is obtained. Example 2: LiMH battery 6V model. As in Example 1, 50 kilograms of accumulators are ground in a humid environment and then a screening is carried out. The part of granulometry greater than the mesh of the screen represents 66% of the starting product. It is made up of 49% steel and scrap 30% plastics 6% ferro-nickel 14% paper The part of grain size smaller than the mesh represents 34% of the starting product. It includes, among others, 44% of nickel and 6% of cobalt. Acid leaching is then carried out, then sodium hydroxide is added until a neutral pH is obtained, sodium hypochlorite to oxidize the nickel and ammonium chloride to complex the cobalt. In this medium, nickel hydroxide

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 black precipitates. 97% of the nickel contained in the starting solution is recovered. By adding sodium sulfide, the cobalt sulfide precipitates. 98% of the cobalt contained is obtained. Example 3: 7.2V NiMH battery.

50 kilograms of accumulators are ground in a humid environment and the grinding and screening are carried out as in Example 1.

The part of granulometry greater than the mesh of the screen represents 70% of the starting product. It is made up of 49% steel and scrap 27% plastics 12% ferro-nickel 12% paper The part of particle size smaller than the mesh represents 30% of the starting product. It includes, among other things, 45% nickel and 5% cobalt.

Acid leaching is carried out and then the reagents of Example 2 are added to separate the cobalt and the nickel. Example 4: Li ion accumulator.

50 kilograms of accumulators are ground in a humid environment and the grinding and screening are carried out as in Example 1.

The part of granulometry greater than the mesh of the screen represents 69% of the starting product. It is made of 38% steel and scrap 42% plastics 16% copper film

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 3% of paper The part of particle size smaller than the mesh represents 31% of the starting product. It includes, among other things, 27% cobalt and 0.1% nickel. The same reagents are used as those mentioned above in order to precipitate the cobalt sulfide which will follow the usual path.

From the above description, it can be seen that the hydrometallurgical treatment process according to the invention comprises, after the initial grinding and screening stages, a succession of chemical stages, the first of which is an attack by an oxidizing acid, the following chemical treatment steps which may be different from those mentioned above. In other words, the essential steps of the process are successively, after the etching step, the step of complexing nickel and cobalt which is followed by two successive precipitation steps, one of which forms a nickel above and the other forming an aforementioned cobalt. As for the steps for separating iron on the one hand and rare earths and lithium on the other hand, they can be intercalated at various stages of the process. For example, the iron separation step, provided between the etching step and the nickel and cobalt complexing step, could be placed after this last step. Likewise, the step of separation of the rare earths and of the lithium which has been provided for after the complexing step, could be placed before it or later in the course of the process. Finally, the precipitation of nickel can take place before or after that of cobalt.

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Claims (8)

 CLAIMS l.- Process for the hydrometallurgical treatment of used accumulators to separate the different constituents and recover valuable by-products, such as nickel and cobalt, characterized in that it comprises the successive stages consisting in grinding simultaneously, in a humid environment, accumulators of different types, in particular accumulators of the NiMH and Li ion type, to carry out a wet screening to separate, on the one hand, a fine part containing nickel, cobalt and other elements such as iron, rare earths and / or lithium, and, on the other hand, sterile materials, to subject the fine part to a chemical attack by an oxidizing acid, by forming a final attack solution, to subject the solution to final attack on nickel and cobalt complexation so as to form stable and highly soluble nickel and cobalt complexes, and to cause precipitation of nickel and cobalt r of their respective complexes. 2.- A method according to claim 1 characterized in that it further comprises a step of precipitation of iron by alkalization with lime, with a pH of the order of 4 to 5.  3.- A method according to claim 2 characterized in that the iron precipitation step is interposed between the chemical attack step and the complexing step. 4.- Method according to any one of the preceding claims, characterized in that it further comprises a step of separation of the rare earths and the <Desc / Clms Page number 11>  lithium by alkalization with sodium hydroxide and carbonation with carbon dioxide, with a pH of 6 to 6.5, resulting in the precipitation of rare earth carbonates and lithium. 5.- Method according to claim 4 characterized in that the step of separation of rare earths and lithium is interposed between the complexing step and the steps of precipitation of nickel and cobalt. 6.- Method according to any one of the preceding claims, characterized in that the complexing step comprises the addition, to the solution, of excess ammonium chloride, with a pH of 4 to 5, resulting in the formation of stable complexes and acidification of the solution. 7.- Method according to any one of the preceding claims, characterized in that the precipitation steps include a nickel separation step carried out by oxidation with bleach, with an alkaline pH (greater than 12), with a alkalization ensured with sodium hydroxide, so as to form a black above-mentioned consisting of a mixture of saline oxide and trivalent nickel hydroxide. 8.- Method according to any one of the preceding claims, characterized in that the precipitation steps include a step of separation of the cobalt carried out by an acidification to a pH of about 4 and a sulfurization by adding sodium sulfide causing precipitation cobalt sulfide.