PROCESS FOR THE RECOVERY OF LITHIUM

Abstract

The present disclosure concerns a process for the concentration of lithium in metallurgical fumes. The process comprises the steps of: —providing a metallurgical molten bath furnace; —preparing a metallurgical charge comprising lithium-bearing material, transition metals, and fluxing agents; —smelting the metallurgical charge and fluxing agents in reducing conditions in said furnace, thereby obtaining a molten bath with an alloy and a slag phase; and, —optionally separating the alloy and the slag phase; characterized in that a major part of the lithium is fumed as LiCl from the molten slag, by addition of alkali or earth alkali chloride to the process. Using a single smelting step, valuable transition metals such as cobalt and nickel also present in the charge are collected in an alloy phase, while the lithium reports to the fumes. The lithium in the fumes is available in concentrated form, suitable for subsequent hydrometallurgical processing.

Claims

1-7. (canceled)

8. A process for the concentration of lithium in metallurgical fumes comprises: providing a metallurgical molten bath furnace; preparing a metallurgical charge comprising lithium-bearing material, transition metals, and fluxing agents; smelting the metallurgical charge and fluxing agents in reducing conditions in said furnace, thereby obtaining a molten bath with an alloy and a slag phase; and, optionally separating the alloy and the slag phase; wherein lithium is fumed as LiCl from the molten slag, by addition of alkali and/or earth alkali chloride to the process.

9. The process according to claim 8, wherein the alkali and/or alkaline earth chloride is added to the process as part of the metallurgical charge, as part of the fluxing agents, or to the liquid slag during or after smelting.

10. The process according to claim 8, wherein the alkali and/or alkaline is added in an amount corresponding to a stoichiometric excess with respect to the Li in the fumes.

11. The process according to claim 10, wherein the stoichiometric excess of alkali and/or alkaline earth chloride amounts to at least 10%.

12. The process according to claim 8, wherein the alkali and/or alkaline earth chloride comprises CaCl.sub.2.

13. The process according to claim 8, wherein the lithium-bearing material also contains nickel and/or cobalt, and wherein a pO.sub.2 is maintained that is sufficiently low to reduce a part of at least one of nickel and cobalt to the alloy phase.

14. The process according to claim 13, wherein the lithium-bearing material comprises Li batteries, their scrap, or their production waste.

Description

EXAMPLES

[0035] End of life batteries with a composition according Table 1 are shredded to allow easier manipulation and dosing.

[0036] A molten bath is then prepared in an alumina crucible of 2 L where 400 g of a starting slag is heated and melted in an induction furnace at a temperature of 1500° C. This starting slag is the result of a previous operation and is used to provide a liquid bath to which the batteries can be added. The composition of the slag is given in Table 2.

[0037] Once the slag is melted, the batteries are added together with limestone and sand fluxes. The additions are made gradually over a period of 2 hours. During this time, O.sub.2 is blown at a rate of 160 L/hour above the bath to combust the metallic Al and carbon present in the batteries.

[0038] After the final addition of battery scrap, CO is blown through the bath at a rate of 60 L/hour for 30 minutes to obtain a homogenous bath and fix the final reduction level. Samples of alloy and slag are taken. The mass balance of slag and alloy is shown in Table 2. The yields are calculated based on the alloy and slag phases only, thus discarding (minor) losses or carry-over to the gas phase.

TABLE-US-00001 TABLE 1 Composition of the batteries Al Co Cu Ni Li Batteries (wt. %) 7 16 9 2.5 2.5

TABLE-US-00002 TABLE 2 Detailed material balance of the smelting operation before chloride addition Al Si Ca Co Cu Ni Li Input Mass (g) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) Starting slag 400 20 13 19   0.2 — 0.1 3.8 Batteries 1000  7 — — 16 9 2.5 2.0 Limestone 300 — 2.2 38.0 — — — — Sand 100 — 46.7 — — — — — Si Ca Co Cu Ni Li Al Output Mass (g) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) (wt. %) Alloy 270 0.0 0.0 58.1 33.1 8.8 0.0 0.0 Slag 950 11.0 19.9 0.5 0.1 0.1 3.8 15.7 Si Ca Co Cu Ni Li Al Yield Mass (g) (%) (%) (%) (%) (%) (%) (%) Alloy 22 0.0 0.0 97.2 99.0 94.6 0.0 0.0 Slag 78 100.0 100.0 2.8 1.0 5.4 100.0 100.0

[0039] While still at 1500° C., argon is blown at a rate of 60 L/hour through the liquid bath to ensure mixing of the slag. From this experiment, it is clear that without the addition of chlorides, the Li remains in the slag.

[0040] Starting each time from the lithium-bearing slag according to above Table 2, 4 different experiments were performed, differing only in the total amount of CaCl.sub.2) added. These 4 amounts represent 0%, 60%, 100% and 120% of the chloride needed for stoichiometric reaction with the Li present in the slag. CaCl.sub.2) is added gradually during the first hours in 12 equal additions every 5 minutes. Prior to the test the CaCl.sub.2) is dried at a temperature of 150° C. in order to remove any water excess. The slag is allowed to react for an additional 30 minutes after the last CaCl.sub.2) addition, while still continuing the gas blowing with Ar.

[0041] Samples of the slag are taken before the CaCl.sub.2) addition, after the final addition, and 30 minutes after the last addition. The results are shown in Table 3, together with the overall yield of the Li to the fumes.

[0042] For a sub-stoichiometric addition of 60%, all the CaCl.sub.2) reacts with the Li in the slag to form volatile LiCl. A 100% stoichiometric amount of CaCl.sub.2) is however not sufficient to vaporize the lithium quantitatively. A super-stoichiometric amount of 120%, equivalent to a 20% excess, achieves a lithium yield of 96%.

[0043] Samples of the fumes all show a lithium concentration of 15%, which corresponds to a LiCl content of more than 90%. The remainder is primarily CaCl.sub.2) present due to mechanical carry over.

TABLE-US-00003 TABLE 3 Li content of the slag in function of time and stoichiometry (CaCl.sub.2) Li content in slag CaCl.sub.2 Before After final 30 min after Li yield to Stoichiometry addition addition final addition fumes  0% 3.8 3.8 3.7  3%  60% 3.8 1.8 1.5 60% 100% 3.8 1.3 0.78 79% 120% 3.8 1.5 0.17 96%

[0044] Similarly to the 4 experiments with CaCl.sub.2), 2 experiments were performed using MgCl.sub.2. The results are shown in Table 4. The lithium yields are markedly lower, though still satisfactory, in particular when using a 200% stoichiometry.

TABLE-US-00004 TABLE 4 Li content of the slag in function of time and stoichiometry (MgCl.sub.2) Li content in slag MgCl.sub.2 Before After final 30 min after Li yield to Stoichiometry addition addition final addition fumes 100% 3.8 2.2 1.9 51% 200% 3.8 1.0 0.8 78%

[0045] NaCl was also tested as chlorinating agent, resulting in a yield of 26% when using a 100% stoichiometry. A super-stoichiometric addition of 250% NaCl result in satisfactory yields of 50% or more. This is shown in Table 5.

TABLE-US-00005 TABLE 5 Li content of the slag in function of time and stoichiometry (NaCl) Li content in slag NaCl Before After final 30 min after Li yield to Stoichiometry addition addition final addition fumes 100% 3.8 3.0 2.8 26% 250% 3.8 2.1 1.8 53%