ENERGY-EFFICIENT PYROMETALLURGICAL PROCESS FOR TREATING LI-ION BATTERIES
20240258597 ยท 2024-08-01
Inventors
Cpc classification
C22B23/021
CHEMISTRY; METALLURGY
International classification
C22B7/00
CHEMISTRY; METALLURGY
Abstract
The present disclosure concerns a 2-step smelting process, for recovering of Ni and Co from batteries and other sources.
The process comprises the steps of: defining an oxidizing level Ox, and a battery-bearing metallurgical charge; oxidizing smelting of the metallurgical charge by injecting an O.sub.2-bearing gas into the melt to reach the defined oxidizing level Ox; and, reducing smelting of the obtained slag using a heat source and a reducing agent.
The process is more energy-efficient than a single-step reducing smelting process and provides for a higher purity alloy and for a cleaner final slag.
Claims
1-12. (canceled)
13. Process for the recovery of valuable metals from a metallurgical charge comprising slag formers, and Li-ion batteries or their derived products containing Co, Ni, metallic Al, and C, comprising the steps of: providing a metallurgical smelting furnace equipped with means for the submerged injection of an O.sub.2-bearing gas; defining an oxidizing level Ox characterizing oxidizing smelting conditions according to the formula:
14. Process for the recovery of valuable metals from a metallurgical charge comprising slag formers, and Li-ion batteries or their derived products containing Co, Ni, metallic Al, and C, comprising the steps of: providing a metallurgical smelting furnace equipped with means for the submerged injection of an O.sub.2-bearing gas; preparing the metallurgical charge using a weight fraction Bf of Li-ion batteries or their derived products in the metallurgical charge; defining an oxidizing level Ox characterizing oxidizing smelting conditions according to the formula:
15. Process according to claim 13, wherein the step of oxidizing smelting is autogenous.
16. Process according to claim 13, wherein the first slag is maintained in the liquid state between the steps of liquid/liquid separation and the step of reducing smelting.
17. Process according to claim 13, wherein the O.sub.2-bearing gas is enriched air or pure O.sub.2.
18. Process according to claim 13, wherein Ox<0.98.
19. Process according to claim 13, wherein said slag formers comprise, by weight, up to 50% CaO, up to 55% Al.sub.2O.sub.3, and up to 65% SiO.sub.2.
20. Process according to claim 13, further comprising a step of transferring the separated first slag to a second furnace suitable for performing a step of reducing smelting, thereby obtaining a second Ni and Co-bearing alloy, and a depleted second slag.
21. Process according to claim 20, wherein said second furnace is an electric furnace.
22. Process according to claim 13, further comprising a step of liquid/liquid separation of the second alloy from the second slag.
23. Process according to claim 22, further comprising a step of recirculating the separated second alloy to the step of autogenous smelting.
24. Process according to claim 13, further comprising the steps of: atomizing the first alloy; and, dissolving the atomized alloy in acidic conditions, thereby obtaining a metal-bearing solution suitable for further hydrometallurgical refining.
Description
EXAMPLE 1
[0071] A metallurgical charge according to Table 1 is prepared with 500 kg batteries, 80 kg limestone and 20 kg silica. Use is made of a cylindrical furnace with a diameter of 1 m, lined with 200 mm magnesia-chrome bricks.
[0072] The charge is continuously added to the furnace at a rate of 500 kg batteries/h, while a bath temperature of 1450? C. is maintained without the need for additional cokes, natural gas or electrical energy. The heat is supplied by the oxidation of Al and C in the batteries, using submerged O.sub.2 injection at a rate of 77 Nm.sup.3/h. These conditions correspond to a CO.sub.2 to (CO+CO.sub.2) ratio of 0.30.
[0073] After 1 h, the slag (1.1) is tapped from the furnace, while the alloy (1.1) is allowed to cool down. This slag, amounting to 188 kg, is fed to a second furnace, while it is still liquid. For this second step, an electric furnace is used.
TABLE-US-00001 TABLE 1 Material balance of the first smelting step Al.sub.2O.sub.3 (Al) SiO.sub.2 CaO Mn Co Cu Ni Fe Li C Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Batteries 500 (5) 7 7 12.3 26.3 3.5 2 15 Limestone 80 4.8 53.3 11.4 Silica 20 100 Output Mass (kg) Slag 1.1 188 21 12.5 24 15 1.1 0.8 0.5 4.5 5.2 Alloy 1.1 233 <0.1 14 26 56 4 Yield Mass (%) Slag 1.1 45 100 100 100 100 6.0 2.4 0.7 47.6 100 Alloy 1.1 55 0 0 0 94.0 97.6 99.3 52.4 0
[0074] The electric furnace is operated at a temperature of 1500? C. and 3.5 kg of cokes is added as reducing agent to the slag. 30 kWh of net electrical power is supplied to the electrical furnace in order to maintain the temperature of the bath.
[0075] After 1 h of reduction, and after decantation, slag (1.2) and alloy (1.2) are tapped from the furnace and allowed to cool down. A detailed material balance is provided in Table 2.
TABLE-US-00002 TABLE 2 Material balance of the second smelting step Al.sub.2O.sub.3 SiO.sub.2 (Al) (Si) CaO Mn Co Cu Ni Fe Li Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) Slag 1.1 188 21 12.5 24 15 1.1 0.8 0.5 4.5 5.2 Output Mass (kg) Slag 1.2 172 22 13.7 26 14.9 <0.1 <0.1 <0.1 0.8 5.4 Alloy 1.2 12 (0.2) 5.7 18 12.5 6 58 0 Yield Mass (%) Slag 1.2 93.5 100 99.8 100 97.4 0 0 0 16.5 100 Alloy 1.2 6.5 (0.2) 0 2.6 100 100 100 83.5 0
EXAMPLE 2 (COMPARATIVE)
[0076] A metallurgical charge according to Table 3 is prepared with 500 kg batteries, 80 kg limestone and 20 kg silica. Use is made of a cylindrical furnace with a diameter of 1 m, lined with 200 mm magnesia-chrome bricks.
[0077] The charge is continuously added to the furnace at a rate of 500 kg batteries/h, while a bath temperature of 1450? C. is maintained without the need for additional cokes, natural gas or electrical energy. 42 Nm.sup.3/hour of O.sub.2 is injected to reach the desired degree of reduction for high metal yields. The applied conditions correspond to a CO.sub.2 to (CO+CO.sub.2) ratio of 0.0, i.e., there is essentially only CO and no CO.sub.2. 220 kWh of net electrical power is needed to maintain the desired temperature.
[0078] After 1 h of reduction, and after decantation, slag (2) and alloy (2) are tapped from the furnace and allowed to cool down. A detailed material balance is provided in Table 3.
TABLE-US-00003 TABLE 3 Material balance of the single step smelting Al.sub.2O.sub.3 SiO.sub.2 (Al) (Si) CaO Mn Co Cu Ni Fe Li C Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Batteries 500 (5) 7 7 12.3 26.3 3.5 2 15 Limestone 80 4.8 53.3 11.4 Silica 20 100 Output Mass (kg) Slag 2 150 25.2 15.8 30.5 6.5 <0.1 <0.1 <0.1 <0.1 5.9 Alloy 2 262 (0.3) 6.6 13.3 23 50 6.6 1.2 Yield Mass (%) Slag 2 36 100 93.3 100 36.1 0.4 0.2 0.1 0 100 Alloy 2 64 0 6.7 0 63.9 99.6 99.8 99.9 100 0
Comparison of Examples 1 and 2
[0079] The first alloy (1.1) produced in Example 1 contains less impurities than the alloy (2) from comparative Example 2. This is especially the case for C and Mn, where the concentration in Example 1 drops below the detection limit of 0.1%, compared to 1.2% for C and 6.6% for Mn. This is also the case for Fe, where the concentration in the first alloy (1.1) is 4%, compared to 6.6% in the alloy (2) according to the comparative Example. The high purity obtained according to Example 1 will make any hydrometallurgical follow-up treatment of the alloy easier and cheaper.
[0080] In addition, the required electrical energy over both steps also differs between Example 1 and 2. In Example 1, only 30 kWh of energy is needed to run the reduction process, compared to 220 kWh in comparative Example 2. The two-step smelting process of Example 1 only required 14% of the electrical energy according to comparative Example 2.
[0081] It should be noted that the specific electrical energy needed in the reducing step will be even lower when using a larger, industrial scale furnace. As the volume to area ratio of the furnace will increase, heath losses will decrease, providing an even larger advantage.
EXAMPLE 3
[0082] A metallurgical charge according to Table 4 is prepared with 500 kg batteries, 80 kg limestone and 20 kg silica, as well as 500 kg of slag and 100 kg of alloy coming e.g. from other battery recycling operations. Use is made of a cylindrical furnace with a diameter of 1 m, lined with 200 mm magnesia-chrome bricks.
TABLE-US-00004 TABLE 4 Material balance of the first smelting step Al.sub.2O.sub.3 SiO.sub.2 (Al) (Si) CaO Mn Co Cu Ni Fe Li C Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Batteries 500 (5) 7 7 12.3 26.3 3.5 2 15 Limestone 80 4.8 53.3 11.4 Silica 20 100 Slag 500 46 21 24 11.5 3 2 3.7 Alloy 100 7 23 9 60 Output Mass (kg) Slag 3.1 922 26.3 13.8 18 10.2 6.4 2 4.5 1.7 3.2 Alloy 3.1 226 <0.1 6.5 22.8 70.7 0.2 Yield Mass (%) Slag 3.1 80 100 100 100 100 80.1 26.4 20.6 97.2 100 Alloy 3.1 20 0 0 0 0 19.9 73.6 79.4 2.8 0
[0083] The charge is continuously added to the furnace at a rate of 500 kg batteries/h, while a bath temperature of 1450? C. is maintained without the need for additional cokes, natural gas or electrical energy. The heat is supplied by the oxidation of Al and C from the batteries using the submerged of 140 Nm.sup.3/h of O.sub.2. These conditions correspond to a CO.sub.2 to (CO+CO.sub.2) ratio of 0.85.
[0084] After one hour, the formed alloy (3.1) is tapped from the furnace and is allowed to cool down. A total of 922 kg of the slag (3.1) is tapped and fed into a second furnace, while it is still liquid. For this step an electric furnace is used.
[0085] The electric furnace is operated at a temperature of 1500? C., and 45 kg of cokes is added to the slag. After 1 hour of reduction, and after decantation, the alloy (3.2) and the slag (3.2) are tapped from the furnace and allowed to cool down. A detailed material balance is provided in Table 5. 190 kWh of net electrical power is supplied to the electric furnace in order to maintain the temperature of the bath.
TABLE-US-00005 TABLE 5 Material balance of the second smelting step Al.sub.2O.sub.3 SiO.sub.2 (Al) (Si) CaO Mn Co Cu Ni Fe Li Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) Slag 3.1 922 26.3 13.8 18 10.2 6.4 4.5 1.7 1.7 3.2 Output Mass (kg) Slag 3.2 707 31.5 18 23.3 10.8 <0.1 <0.1 <0.1 <0.1 3.7 Alloy 3.2 150 (0.4) 10.2 39 12 27.8 11.2 0 Yield Mass (%) Slag 3.2 82 100 99 100 83 0 0 0 0 100 Alloy 3.2 18 0 1 0 17 100 100 100 100 0
[0086] This Example illustrates that the process allows for autogenous operation, even when a significant amount of the charge comprises other components than batteries. A higher degree of oxidation is however needed: 0.85 in Example 3, compared to 0.30 In Example 1. This results in a first alloy (3.1) that is rich in Ni and depleted in Fe. These specifications are advantageous. However, the Ni and Co yields of the first smelting step are lower. This lower yield may be fully compensated by recycling alloy from the second smelting step to the first smelting step.
EXAMPLE 4
[0087] The Li-ion batteries with a composition shown in Table 6 are smelted according to the invention in a cylindrical furnace with a diameter of 1 meter, lined with 200 mm magnesia-chrome bricks.
[0088] A metallurgical charge is prepared comprising 180 kg limestone and 150 kg silica as fluxing agents, and 500 kg Li-ion batteries.
[0089] The mixture is continuously added at a rate of 500 kg batteries/h to the furnace and a bath temperature of 1350? C. is maintained without the need for cokes, natural gas or electrical energy. The energy is supplied by the oxidation of Al and C from the batteries using submerged O.sub.2 injection. 91 Nm.sup.3/hour of O.sub.2 is injected for the charge shown in table 6. These conditions correspond to a CO.sub.2/(CO+CO.sub.2) ratio of 0.45.
[0090] After 1 h, the phases are tapped from the furnace. The alloy (4.1) is allowed to cool down. The slag (4.1), amounting to 400 kg, is fed to a second furnace, while it is still liquid. For this second step, an electric furnace is used.
TABLE-US-00006 TABLE 6 Material balance of the first smelting step Al.sub.2O.sub.3 (Al) SiO.sub.2 CaO Mn Co Cu Ni Fe Li C Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Batteries 500 (5) 7.2 7.8 12.5 7.2 1 3 15 Limestone 180 4.8 53.3 11.4 SiO.sub.2 150 100 Output Mass (kg) Slag 4.1 400 8.4 39.5 25 8.9 1.5 0.6 0.5 1 3.7 Alloy 4.1 130 <0.1 25 46 27 1 Yield Mass (%) Slag 4.1 75 100 100 100 100 6.0 2.4 0.7 47.6 100 Alloy 4.1 25 0 0 0 0 94.0 97.6 99.3 52.4 0
[0091] After the first step, the slag is separated and transported to an electric furnace where a temperature of 1500? C. is applied and 10 kg of cokes are added per hour together with 400 kg of slag. After 1 h of reduction and decantation, the alloy and the slag are tapped from the furnace and allowed to cool down. A detailed material balance is provided in Table 7.
TABLE-US-00007 TABLE 7 Material balance of the second smelting step SiO.sub.2 Al.sub.2O.sub.3 (Si) CaO Mn Co Cu Ni Fe Li Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) Slag 4.1 400 8.4 39.5 25 8.9 1.5 0.6 0.5 1 3.7 Output Mass (kg) Slag 4.2 375 6.7 43 27 9.5 <0.1 <0.1 <0.1 0.8 3.7 Alloy 4.2 16 (0.2) 5.8 44 14 13 23 BDL Yield Mass (%) Slag 4.2 96 100 99.9 100 97.5 0 0 0 45 100 Alloy 4.2 4 0 0.1 0 2.5 100 100 100 55 0
EXAMPLE 5
[0092] A metallurgical charge according to Table 8 is prepared with 500 kg Li-ion batteries, 100 kg limestone and 40 kg silica. Use is made of a cylindrical furnace with a diameter of 1 m, lined with 200 mm magnesia-chrome bricks.
[0093] The charge is continuously added to the furnace at a rate of 500 kg batteries/h, while a bath temperature of 1550? C. is maintained without the need for additional cokes, natural gas or electrical energy. The heat is supplied by the oxidation of Al and C in the batteries, using submerged O.sub.2 injection at a rate of 77 Nm.sup.3/h. These conditions correspond to a CO.sub.2 to (CO+CO.sub.2) ratio of 0.30.
[0094] After 1 h, the slag (5.1) is tapped from the furnace, while the alloy (5.1) is allowed to cool down. This slag, amounting to 188 kg, is fed to a second furnace, while it is still liquid. For this second step, an electric furnace is used.
TABLE-US-00008 TABLE 8 Material balance of the first smelting step Al.sub.2O.sub.3 (Al) SiO.sub.2 CaO Mn Co Cu Ni Fe Li C Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Batteries 500 (5) 2.4 2.6 5 20.8 1 2 15 Limestone 100 4.8 53.3 11.4 Silica 40 100 Output Mass (kg) Slag 1.1 188 21 22.4 30 6.2 0.6 0.3 0.5 1 5.3 Alloy 1.1 143 <0.1 8 16 72 2 Yield Mass (%) Slag 1.1 57 100 100 100 100 9.0 2.4 0.9 39.7 100 Alloy 1.1 43 0 0 0 91.0 97.6 99.1 60.3 0
[0095] The electric furnace is operated at a temperature of 1500? C. and 3.5 kg of cokes is added as reducing agent to the slag.
[0096] After 1 h of reduction, and after decantation, slag (5.2) and alloy (5.2) are tapped from the furnace and allowed to cool down. A detailed material balance is provided in Table 9.
TABLE-US-00009 TABLE 9 Material balance of the second smelting step Al.sub.2O.sub.3 SiO.sub.2 (Al) (Si) CaO Mn Co Cu Ni Fe Li Input Mass (kg) (%) (%) (%) (%) (%) (%) (%) (%) (%) Slag 5.1 188 21 22.4 30 6.2 0.6 0.3 0.5 1 5.3 Output Mass (kg) Slag 5.2 175 20 25 33 6.5 <0.1 <0.1 <0.1 <0.1 5.4 Alloy 5.2 5 (0.3) 9.4 22 11 20 37 0 Yield Mass (%) Slag 5.2 97.2 100 99.9 100 96 0 0 0 0 100 Alloy 5.2 2.8 (0.1) 0 4 100 100 100 100 0
CONCLUSION
[0097] Example 4 and 5 show an autogenous process having different temperatures of the first smelting step.
[0098] Comparing the used battery fraction of the feed, with the minimum required battery fraction (Bf) for autogenous smelting, using the battery composition and oxidizing level, Ox=pCO.sub.2/(pCO+pCO.sub.2)
[0099] Example 4 has a battery fraction of 60%, while 59% is required for autogenous smelting. Example 4 thus shows the minimum required battery fraction for autogenous smelting for the given battery composition and chosen oxidizing level. The process is operated at 1350? C., sufficient to keep both the slag and alloy liquid.
[0100] Example 5 has a battery fraction of 78%, while a 69% is required for autogenous smelting. Example 5 thus uses a higher battery fraction than the minimum required for autogenous smelting and the process is operated at 1550? C.