Recovery of nickel and cobalt from Li-ion batteries or their waste
The present invention lies in the field of pyrometallurgy and discloses a process and a slag suitable for the recovery of Ni and Co from Li-ion batteries or their waste. The slag composition is defined according to: 10%<MnO<40%; (CaO+1.5*Li 2 O)/Al 2 O 3 >0.3; CaO+0.8*MnO+0.8*Li 2 O<60%; (CaO+2*Li 2 O+0.4*MnO)/SiO 2 ≥2.0; Li 2 ≥1%; and, Al 2 O 3 +SiO 2 +CaO+Li 2 O+MnO+FeO+MgO>85%. This composition is particularly adapted to limit or avoid the corrosion of furnaces lined with magnesia-bearing refractory bricks.
1. Process for the recovery of Ni and Co from Li-ion batteries or their waste, comprising the steps:
providing a furnace lined with magnesia-bearing refractory bricks;
providing a charge comprising slag formers, and Li-ion batteries or their waste; and,
smelting the charge in reducing conditions, thereby obtaining an alloy containing the major part of the Ni and Co, and a slag;
characterized in that the slag has a percent composition by weight according to:
10%<MnO<40%;
(CaO+1.5*Li 2 O)/Al 2 O 3 >0.3;
CaO+0.8*MnO+0.8*Li 2 O<60%;
(CaO+2*Li 2 O+0.4*MnO)/SiO 2 >2.0;
Li 2 O>1%; and,
Al 2 O 3 +SiO 2 +CaO+Li 2 O+MnO+FeO+MgO>85%.
2. Process according to claim 1 , wherein the content of MnO in the slag is greater than 10% and less than or equal to 30%.
3. Process according to claim 1 , wherein the content of CaO in the slag is greater than or equal to 15% and less than or equal to 50%.
4. Process according to claim 1 , wherein the content of Al 2 O 3 in the slag is less than or equal to 50%.
5. Process according to claim 1 , wherein the content of Fe in the slag is less than or equal to 25%.
6. Process according to claim 1 , wherein the sum of Al 2 O 3 , SiO 2 , CaO, Li 2 O, MnO, FeO and MgO is greater than or equal to 90%.
7. Process according to claim 1 , wherein (CaO+2*Li 2 O+0.4*MnO)/(SiO 2 +0.2*Al 2 O 3 ) is >1.5.
8. Process according to claim 1 , wherein the step of smelting the charge is performed at a temperature of at least 1400° C. and at most 300° C. above the liquidus point of the slag, thereby avoiding overheating.
9. Process according to claim 1 , the smelting step comprising the further steps:
sampling the slag;
cooling down the slag sample and assessing its color; and,
in case the slag sample is green, terminating the smelting step; or,
in case the slag sample is not green, proceeding with the smelting step after adjusting the pO 2 -level to achieve more reducing conditions.
10. Process according to claim 1 , wherein a pO 2 -level is adjusted to 10 −7 >pO 2 >10 −12 .
11. Process according to claim 9 , wherein the color of the slag is green.
12. Process according to claim 1 , wherein the furnace is an electric furnace.
13. Process according to claim 1 , wherein a Li-containing metallurgical slag partially or fully replaces slag formers in the step of providing a charge comprising slag formers, wherein the Li-containing metallurgical slag has a percent composition by weight according to:
10%<MnO<40%;
(CaO+1.5*Li 2 O)/Al 2 O 3 >0.3;
CaO+0.8*MnO+0.8*Li 2 O<60%;
(CaO+2*Li 2 O+0.4*MnO)/SiO 2 >2.0;
Li 2 O>1%; and,
Al 2 O 3 +SiO 2 +CaO+Li 2 O+MnO+FeO+MgO>85%.