Process for acquiring lithium from brine and for recovering lithium when recycling lithium ion accumulators

Abstract

An adsorption process for acquiring lithium from brine, in which the desorption occurs with an eluent, whereby the eluent is a mixture of water and acetic acid and/or water and sodium peroxydisulfate and/or water and ammonium peroxydisulfate.

Claims

1. Process for producing a lithium concentrate from brine, containing lithium ions, comprising the following steps: a) introduction of brine into an adsorption column at least partially filled with an adsorption agent so that lithium ions are adsorbed by the adsorption agent; b) introduction of an eluent into the adsorption agent so that the lithium ions adsorbed by the adsorption agent are desorbed, characterized in that, before introduction into the adsorption agent, the eluent is a mixture of water and acetic acid and/or water and sodium peroxydisulfate and/or water and ammonium peroxydisulfate.

2. Process as per claim 1, characterized in that the proportion of acetic acid in the eluent is between 0.1% and 100%.

3. Process as per claim 1, characterized in that the proportion of ammonium peroxydisulfate in the eluent is between 0.05% and 65%.

4. Process as per claim 1, characterized in that the proportion of sodium peroxydisulfate in the eluent is between 0.05% and 60%.

5. Process as per claim 1, characterized in that it also takes place at a temperature below 70° C.

6. Process as per claim 1, characterized in that the process step “b) introduction of the eluent” is repeated one or more times, and that during the repetition(s) the acidic solution containing lithium ions from the previous desorption step is used.

7. Process as per claim 6, characterized in that the repetition of the process step “b) introduction of the eluent” takes place at a lower temperature than the first time the process step “b)” is performed.

8. Process as per claim 1, characterized in that, between the process steps “a) introduction of the brine” and “b) introduction of the eluent”, there is an interim step, namely “introduction of water into the adsorption agent”, so that Na, K, Ca and Mg ions adsorbed by the adsorption agent are desorbed and transported from the adsorption column with the drainage of the water.

9. Process as per claim 1, characterized in that the adsorption agent comprises manganese oxide containing lithium, as well as a polymer as a bonding agent.

10. Process as per claim 1, characterized in that the adsorption agent comprises lithium titanium oxide (LiTiO), and/or lithium-aluminum layered double hydroxide chloride (LiAn.2xAl(OH).sub.3.mH.sub.2O, with “An”=chlorine (Cl), bromine (Br), or iodine (I), “m” is a numerator) and a polymer as a bonding agent.

11. Process as per claim 9, characterized in that the bonding agent is polyvinyl chloride.

12. Process as per claim 1, characterized in that the brine stems from a pyrometallurgic recycling process of lithium ion accumulators.

13. Process as per claim 1, characterized in that the brine stems from a hydrometallurgic recycling process of lithium ion accumulators.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] The figures show the following:

[0039] FIG. 1 a flow diagram of a process described by the invention, and

[0040] FIG. 2 a simplified view of an adsorption column suitable to conduct the process described by the invention.

DETAILED DESCRIPTION

[0041] The process described by the invention is conducted with an adsorption column 21 as shown in FIG. 2.

[0042] The process described by the invention begins in a first step 1, in which the adsorption column 21 is filled with water. The adsorption column 21 contains an adsorption agent 23 that adsorbed the lithium ions in the brine. If further ions are contained in the brine, at least some of these ions are also adsorbed by the adsorption agent.

[0043] The brine is then expelled from the adsorption column 21 in another step (block 3).

[0044] In further, additional steps 5 or 7, the adsorption column 21 is filled with water and the water is then expelled from the adsorption column 21. The water is used to dissolve and desorb non-lithium ions that have been adsorbed by the adsorption agent. Otherwise these ions contaminate the acidic solution enriched with lithium ions. It is thus beneficial if these ions are desorbed before the desorption of the lithium ions. If the brine led to the adsorption column 21 contains only very few or none of these contaminants, steps 5 and 7 can be omitted.

[0045] The lithium ions adsorbed by the adsorption agent 23 are then desorbed (steps 9 and 11). Block 9 comprises the filling of the adsorption column 21 with an acidic solution as per claim 1. Most of the lithium ions adsorbed by the adsorption agent are thus desorbed. A certain proportion of the lithium ions remain in the adsorption agent, however.

[0046] In a further step 11, the eluent enriched with lithium ions is expelled.

[0047] Depending on the effectiveness of the desorption process, steps 9 and 11 can be repeated once or multiple times. The adsorption column 21 is thus filled with the acidic solution from the previous desorption step, in which it was enriched with lithium ions, whereupon it is expelled again. These repetitions can be performed until an optimal ratio between the loss of adsorption agent and maximization of the desorption of the lithium ions is achieved. It must be considered that only about 0.4% of the adsorption agent is lost during each desorption process with the acidic solution described by this invention. It is thus possible to perform steps 9 and 11 two or three times. Even then, the loss of adsorption agent only amounts to about 0.8% or 1.2%. This is only a fraction of the loss resulting from desorption with an acidic solution based on muriatic acid. In the latter case, each desorption step results in loss of about 5% of the adsorption agent.

[0048] Following desorption (steps 9 and 11), the acidic solution enriched with lithium ions may be further concentrated. For example, this may be the case with multi-step electrolysis, as described in U.S. Pat. No. 6,764,584 B2. The resulting, relatively highly concentrated acidic solution can then be further processed into a precursor for the production of lithium ion batteries.

[0049] It has been discovered that the desorption process is sufficiently effective even at decreasing temperatures. It is thus beneficial if the acidic solution is conveyed into the adsorption column 21 a second time at low temperatures, such as 40° C. or 30° C., or even lower.

[0050] FIG. 2 shows the design of an adsorption column 21 suitable for conducting the process.

[0051] The interior of the adsorption column 21 contains the adsorption agent. It does not take up the entire interior of the adsorption column 21.

[0052] The adsorption column 21 comprises an inlet 25 and an outlet 27. The brine is supplied via the inlet 25 and expelled via the outlet 27.

[0053] The acidic solution can be supplied and expelled via the inlet 25 or the outlet 27. However, it is also possible for an additional connection 29 to be used for the supply and expulsion of the acidic solution. This connection 29 can, as shown in FIG. 2, be located at the bottom of the adsorption column 21. But it can also be located at the top of the adsorption column 21 (not pictured.)

[0054] In short: The process described by the invention can be conducted if the desorption agent is supplied to the adsorption column 21 from the top or the bottom.

[0055] The required pumps and valves are not pictured in FIG. 2.