Process for recycling cobalt-bearing materials

Abstract

The present invention concerns the recovery of cobalt from cobalt-bearing materials, in particular from cobalt-bearing lithium-ion secondary batteries, from the spent batteries, or from their scrap. A process is divulged for the recovery of cobalt from cobalt-bearing materials, comprising the steps of: providing a converter furnace, charging slag formers and one or more of copper matte, copper-nickel matte, and impure alloy into the furnace, and injecting an oxidizing gas so as to smelt the charge in oxidizing conditions, thereby obtaining a molten bath comprising a crude metal phase, and a cobalt-bearing slag, and separating the crude metal from the cobalt-bearing slag, characterized in that the cobalt-bearing materials are charged into the furnace. This process is particularly suitable for recycling cobalt-bearing lithium-ion secondary batteries. Cobalt is concentrated in a limited amount of converter slag, from which it can economically be retrieved, together with other elements such as copper and/or nickel.

Claims

1. Process for the recovery of cobalt from cobalt-bearing materials, comprising: providing a converter furnace; feeding cobalt-bearing materials, slag formers, and oner or more of copper matte, copper-nickel matte, and impure alloy containing copper and/or nickel into the converter furnace, injecting an oxidizing gas into the converter furnace, thereby oxidizing any sulfidic materials present in the copper matte or copper-nickel matte to form sulfur dioxide, and obtaining a molten bath in the converter furnace comprising a crude metal phase and a cobalt-bearing slag, but free of sulfur; and, separating the crude metal phase from the cobalt-bearing slag; wherein the cobalt-bearing materials comprise secondary batteries, spent batteries, or their scrap and wherein more than 90% by weight of the cobalt present in the cobalt-bearing materials is recovered in the cobalt-bearing slag.

2. Process according to claim 1, wherein the more than 90% by weight of the cobalt present in the cobalt-bearing materials is recovered in the cobalt-bearing slag, by adjusting the amount of oxidizing gas.

3. Process for the recovery of cobalt from cobalt-bearing materials according to claim 1, wherein the cobalt in the cobalt-bearing slag amounts to between 2% and 20% by weight.

4. Process for the recovery of cobalt from cobalt-bearing materials according to claim 1, further comprising a step of recovering cobalt and copper from the cobalt-bearing slag.

5. Process for the recovery of cobalt from cobalt-bearing materials according to claim 4, wherein the step of recovering cobalt and copper from the cobalt-bearing slag comprises an acidic aqueous leaching operation.

6. Process for the recovery of cobalt from cobalt-bearing materials according to claim 4, wherein the step of recovering cobalt and copper from the cobalt-bearing slag comprises a reducing smelting operation.

7. Process of claim 1, comprising feeding cobalt-bearing materials, slag formers, impure alloy and one or more of copper matte and copper-nickel matte into the converter furnace.

8. Process of claim 1, wherein the converter furnace is operated in tandem with a smelter.

9. Process of claim 1, further comprising a smelting step, wherein the one or more of copper matte, copper-nickel matte, and impure alloy are produced in the smelting step.

Description

(1) This comparative Example 1 illustrates operating conditions for smelter and converter equipment working in tandem to treat typical copper-iron sulfidic ores. The matte produced in the smelter is fed to the converter. No batteries are added in this Example. The smelter is operated at a mean temperature of about 1175 C.

(2) The converter slag still contains a substantial amount of copper and will typically be recycled to the smelter. Alumina is suitably low in the smelter slag, and insignificant in the converter slag. The smelter slag is clean and suitable for re-use. The converter is operated at a mean temperature of about 1300 C.

(3) TABLE-US-00002 TABLE 2 Reference charge with cobalt-bearing materials on smelter (comparative Example 2) Smelter Composition (%) Feed rate Fe Co Mn Al Si Li Input (t/h) S Cu Ni (FeO) (CoO) (MnO) (Al.sub.2O.sub.3) (SiO.sub.2) (Li.sub.2O) Charge 100 18 25 0.6 20 1 15 Flux 25 100 Batteries 20 10 4 14 10 2 12 0 4.1 Output Matte 43.76 25 59.2 2.88 10.4 0.91 Slag 104.3 1.04 0.13 2.05 22.5 0.495 5.31 38.4 0.786 Converter Composition (%) Feed rate Fe Co Mn Al Si Li Input (t/h) S Cu Ni (FeO) (CoO) (MnO) (Al.sub.2O.sub.3) (SiO.sub.2) (Li.sub.2O) Matte 43.76 25 59.23 2.88 10.4 0.91 Flux 2.9 100 Output Blister 26.6 95.4 4.64 Slag 11.36 4.56 0.22 51.6 4.48 25.5

(4) This comparative Example 2 illustrates typical working conditions for the smelter and converter equipment treating copper-iron sulfidic ores similar to comparative Example 1, with however the difference that cobalt-bearing lithium-ion secondary batteries are fed to the smelter. The matte produced in the smelter is fed to the converter. The operating temperatures are according to Example 1.

(5) Alumina in the smelter slag amounts to more than 5%, a figure indicating that the amount of batteries in the feed is against its upper bound.

(6) Cobalt thus gets diluted in the smelter slag and in the converter slag, in concentrations rendering recovery particularly arduous and expensive.

(7) TABLE-US-00003 TABLE 3 Reference charge with cobalt-bearing materials on converter (Example according to the invention) Smelter Composition (%) Feed rate Fe Co Mn Al Si Li Input (t/h) S Cu Ni (FeO) (CoO) (MnO) (Al.sub.2O.sub.3) (SiO.sub.2) (Li.sub.2O) Charge 100 18 25 0.6 20 1 15 Flux 20 100 Output Matte 40 25 60 1.35 10.0 Slag 88.5 1.13 0.1 23.3 1.13 39.5 Converter Composition (%) Feed rate Fe Co Mn Al Si Li Input (t/h) S Cu Ni (FeO) (CoO) (MnO) (Al.sub.2O.sub.3) (SiO.sub.2) (Li.sub.2O) Matte 40 25 60 1.35 10 Flux 4.3 100 Batteries 20 10 4 14 10 2 12 0 4.1 Output Blister 26.2 95.1 4.9 Slag 28.9 3.60 0.19 30.2 8.79 1.78 15.7 14.9 2.83

(8) This Example according to the invention illustrates typical working conditions for the smelter and converter equipment treating copper-iron sulfidic ores similar to comparative Examples 1 and 2, with however the difference that cobalt-bearing lithium-ion secondary batteries are fed to the converter instead of to the smelter. The matte produced in the smelter is also fed to the converter. The operating temperatures are according to Examples 1 and 2.

(9) Alumina is suitably low in the smelter slag, but amounts to 15.7% in the converter slag. As explained above, such a high alumina concentration is acceptable in view of the conditions prevailing in a converter.

(10) The smelter slag contains no cobalt, the cobalt being now concentrated in a low amount of converter slag. It is suitable for ecological re-use. The economic recovery of cobalt from the converter slag is rendered possible.