Method for reclaiming active material from a galvanic cell, and an active material separation installation, particularly an active metal separation installation

Abstract

A method for retrieving active material from a galvanic cell is provided. The galvanic cell includes an active material, a support for the active material and a binder for bonding the active material and the support. The method includes the following steps: (a) crushing the cells, in particular under inert gas or in a vacuum, so that solid cell fragments are also formed, (b) heating the solid cell fragments up to the decomposition temperature (T.sub.z), which is high enough to make the binder decompose so that it loses its binding properties, preferably under inert gas or in a vacuum, such that heat treated cell fragmented are formed, and (c) classifying the heat treated cell fragments, whereby (d) the classifying comprises air jet sieving and (e) the air jet sieving is carried out in such a way that the active material is separated from the support.

Claims

1. A method for retrieving active material from a galvanic cell, wherein the galvanic cell comprises an active material, a support for the active material and a binder for bonding the active material and the support, comprising the steps of: (a) crushing the galvanic cell, under inert gas or in a vacuum, to form solid cell fragments, (b) heating the solid cell fragments up to a decomposition temperature, which is high enough to make the binder decompose so that the binder loses its binding properties to form heat treated cell fragments, and then (c) separating the active material from the support by classifying the heat treated cell fragments by means of an air jet sieve, wherein a collision of the active material and support with a sieve and/or baffle plate of the air jet sieve causes the the separation of the active material from the support.

2. The method according to claim 1, wherein the active material of the galvanic cell is formed of particles, and the air jet sieve has a mesh size that is up to 200 times a specified diameter, wherein the specified diameter corresponds to a diameter which is larger than the diameter of 90% of all particles and which is smaller than the diameter of 10% of all particles.

3. The method according to claim 2, wherein the mesh size of the sieve is a maximum of 200 μm.

4. The method according to claim 1, wherein the galvanic cell comprises at least one anode and at least one cathode, wherein the at least one anode and at least one cathode are heated up together and wherein the resulting heat treated cell fragments are classified together in the same air jet sieve.

5. The method according to claim 1, further comprising the steps of: drying the solid cell fragments at a drying temperature to form dry cell fragments and drying vapours and at least partly condensing the drying vapours to retrieve electrolyte solvents before heating the solid cell fragments up to the decomposition temperature.

6. The method according to claim 1, wherein the heating of the solid cell fragments up to the decomposition temperature takes place under inert gas or in a vacuum.

7. The method according to claim 5, further comprising the steps of: treating the dry cell fragments by means of magnetic separation to form iron-free cell fragments, and classifying the iron-free cell fragments.

8. The method according to claim 1, wherein the galvanic cell comprises an electrolyte and at least a portion of the electrolyte is removed during crushing of the galvanic cell under inert gas.

9. The method according to claim 1, wherein the crushing of the galvanic cell is carried out in such a way that the median diameter of the solid cell fragments does not fall below 200 μm.

10. The method according to claim 1, wherein the binder evaporates at the decomposition temperature.

Description

(1) In the following the invention is further explained with reference to the attached drawings. They show:

(2) FIG. 1 a flow chart of an active material separation system according to the invention, for carrying out the method according to the invention and

(3) FIG. 2 an exploded drawing of a version of a collision separator of the active material separation system according to FIG. 1.

(4) FIG. 1 shows a flow chart of the active material separation system 10 according to the invention, which possesses a cell crushing device 12, to which galvanic cells 14.1, 14.2, . . . are supplied. The cell crushing device 12 is gas-proof and comprises a gas washing column 16, a circulation pump 18 and a condenser 20, by means of which inert gas, for example nitrogen, is circulated and purified. The cell crushing device additionally comprises an inert gas tank 22 for adjusting the inert gas pressure in the cell crushing device 12. The condenser 20 possesses an electrolyte outlet 24, through which condensed electrolyte can be removed.

(5) A stirred reactor 26 can be set up in the direction of material flow behind the cell crushing device 12, which is set up to remove the liquid fraction from the cell crushing device 12, and to stir it, so that the conducting salt from the galvanic cells 14 (references without a number after them indicate the generic object) can be retrieved.

(6) A pre-dryer 28 is set up in the direction of material flow behind the cell crushing device 12, which is connected to the cell crushing device 12 via a pipe 30. During crushing of the galvanic cells 14, resulting cell fragments arrive at the pre-dryer 28 via the pipe 30. Here there is a dry temperature T.sub.t of preferably T.sub.t=80° C. The pre-dryer 28 comprises a circulation pump 32 and a condenser 34 for condensing electrolyte, which can be removed via the pipe 36. The pre-dryer 28 is designed to be gas-proof and is flushed with inert gas by the circulation pump 32.

(7) A separator 38 is set up in the direction of material flow behind the pre-dryer 28, which comprises a magnetic separator and, if necessary, an eddy flow separator also. The magnetic material is removed via a discharge pipe 40. Non-magnetic material arrives at a classifier 42, for example a zigzag classifier. The classifier 42 is, like the separator 38, optional, and is then particularly advantageous if only the cathode of the galvanic cells is to be re-used, as in the present case. The anodes are also removed in the same way as the pouch foils, if present.

(8) An oven 44 is set up in the direction of material flow behind the classifier 42, in which there is a decomposition temperature T.sub.z between 400 and 600° C. The binder, for example polyvinylidene flouride (PVDF), thus decomposes. The decomposed product is removed via the discharge pipe 46 and taken to the gas washing column 48.

(9) An air jet sieve 50 is set up in the direction of material flow behind the oven 44. The air jet sieve 50 comprises a sieve element 52. The heat treated cell fragments coming from the oven 44 are delivered to the air jet sieve. This is characterised by the fact that an air flow is supplied above or below the finely meshed sieve element (20-200 μm). This air flow is drawn from below the sieve. As a result of the air flow, the electrode fragments are whirled up and then placed under mechanical stress. This stress assists in the separation of support foil and coating. The active material particles are thus drawn by the flow of air through the meshes and are subsequently separated off by a cyclone. The foil fraction (aluminium and copper) is held back by the sieve element and can be obtained as a metal fraction and used again.

(10) FIG. 2 shows an exploded view of a collision separator or an air jet sieve. The heat treated cell fragments that are to be separated are taken to one side of the sieve, and a moving air flow is blown from the other side, for example by way of a moving nozzle system, in the direction of the sieve. The cell fragments are thus hurled against the baffle plate, which takes the form of a baffle cover, and are separated there into the support and the coating.

(11) On the side of the sieve from which the air jet is blown onto the sieve there is an intake nozzle, by means of which the blown-in air is removed together with the coating. The baffle plate is kept apart from the sieve by spacer rings.

(12) TABLE-US-00001 List of reference numbers 10 Active material separation system 12 Cell crushing device 14 Galvanic cell 16 Gas washing column 18 Circulation pump 20 Condenser 22 Inert gas tank 24 Electrolyte outlet 26 Stirred reactor 28 Pre-dryer 30 Pipe 32 Circulation pump 34 Condenser 36 Pipe 38 Separator 40 Discharge pipe 42 Classifier 44 Oven 46 Discharge pipe 48 Gas washing column 50 Air jet sieve 52 Sieve element 54 Particle 56 Discharge pipe 58 Cyclone T.sub.t Dry temperature T.sub.z Decomposition temperature