A METHOD FOR PROCESSING LITHIUM IRON PHOSPHATE BATTERIES
A method of processing a black mass material feed material can include a) receiving a black mass material feed material; b) acid leaching the black mass material at a pH that is less than 4, thereby producing a pregnant leach solution (PLS) comprising at least 80% the lithium from the black mass feed material, and at least a portion of the iron and the phosphorous from the black mass feed material; providing a first intermediary solution after completing step b); and separating at least 90% of the iron and the phosphorous from the first intermediary solution to provide an output solution.
1 . A method of processing a black mass material feed material comprising materials liberated from within lithium iron phosphate (LFP) battery materials, the method comprising:
a) receiving a black mass feed material comprising iron, phosphorous, graphite and lithium derived from LFP batteries and having a first concentration of lithium;
b) acid leaching the black mass material at a pH that is less than 4, thereby producing a pregnant leach solution (PLS) comprising less graphite than the black mass feed material, at least 80% the lithium from the black mass feed material, and at least a portion of the iron and the phosphorous from the black mass feed material, the PLS having a second concentration of lithium that is greater than the first concentration of lithium;
c) providing a first intermediary solution after completing step b); and
d) separating at least 90% of the iron and the phosphorous from the first intermediary solution to provide an output solution having less iron and phosphate than the first intermediary solution and having a third concentration of lithium that is greater than the second concentration.
2 . The method of claim 1 , wherein the first intermediary solution comprises the PLS.
3 . The method of claim 1 , wherein the PLS produced in step 1 b ) comprises copper and further comprising processing the PLS to remove substantially all of the copper and produce a copper-depleted PLS, whereby the first intermediary solution comprises the copper-depleted PLS.
4 . The method of claim 3 , wherein processing the PLS to remove substantially all of the copper comprises at least one of a copper solvent extraction process, a copper cementing process and a copper sulphide precipitation process.
5 . The method of claim 4 , wherein processing the PLS to remove substantially all of the copper comprises sulfide precipitation of the PLS, whereby copper sulphide is precipitated from the PLS to produce the copper-depleted PLS.
6 . The method of claim 5 , wherein the sulfide precipitation of the PLS comprises adding a reductant comprising at least one of sodium hydrosulphide and sodium sulphide to the PLS.
7 . The method claim 6 , wherein the sulfide precipitation is conducted with a residence time of between about 0.5 and about 4 hours and at an operating temperature that is between approximately 5 and 80 degrees Celsius.
8 . The method of claim 7 , wherein the residence time is 2 hours and the operating temperature is about 20 degrees Celsius.
9 . The method of claim 5 , wherein the sulfide precipitation is conducted with a solution pH that is less than 4.
10 . The method of claim 9 , wherein the solution pH is about 1.5.
11 . The method of claim 5 , wherein the sulfide precipitation produces a filtrate solution having an oxidation reduction potential (ORP) between −200 mV and 0 mV.
12 . The method of claim 11 , further comprising adjusting the ORP of the filtrate solution to be equal to or above 400 mV by introducing an oxidant into the filtrate solution, thereby producing the copper-depleted PLS.
13 . The method of claim 5 , wherein at least 99% of the copper is precipitated out of the PLS.
14 . The method of any one of claims 1 to 13 , wherein the separating in step 1 d ) comprises precipitating at least the iron and the phosphorous from the first intermediary solution via hydroxide precipitation, thereby producing the output solution.
15 . The method of claim 14 , further comprising adjusting a pH of the first intermediary solution to be between about 8 and 11 to promote the precipitation of the iron and the phosphorous.
16 . The method of claim 14 , further comprising adjusting the pH to be between 10 and 10.5.
17 . The method of claim 14 , wherein adjusting the pH comprises introducing at least one of calcium hydroxide and sodium hydroxide as a precipitating reagent during the hydroxide precipitation.
18 . The method of claim 17 , wherein adjusting the pH comprises adding Ca(OH) 2 to the first intermediary solution.
19 . The method of claim 17 , wherein adjusting the pH comprises adding sodium hydroxide to the first intermediary solution.
20 . The method of claim 17 , further comprising adjusting the first intermediary solution so that a mol ratio of iron to phosphorous (Fe:P) in the first intermediary solution is between about 1 and about 4.
21 . The method of claim 20 , wherein the mol ratio of iron to phosphorous (Fe:P) in the first intermediary solution is about 2.
22 . The method of claim 20 or 21 , wherein the mol ratio of iron to phosphorous (Fe:P) in the first intermediary solution may be adjusted by adding an iron-containing reagent into the first intermediary solution.
23 . The method of any one of claims 1 to 22 , wherein step 1 d ) further comprises introducing a flocculant into the first intermediary solution.
24 . The method of claim 23 , wherein the flocculant may include C—(N—COCO-1, 3 diaminopropane acetate).
25 . The method of claim 23 or 24 , wherein the flocculant may have a concentration of between about 10 ppm and about 30 ppm in the first intermediary solution.
26 . The method of claim 14 , further comprising filtering the first intermediary solution to remove solid ferrous phosphate particle and produce the output solution.
27 . The method of claim 1 , further comprising pre-conditioning the black mass material prior to step 1 b ) by adding a solvent to the black mass material to provide a flowable black mass slurry.
28 . The method of claim 27 , wherein the flowable black mass slurry has a pulp density of between about 15 wt % and about 35 wt %.
29 . The method of any one of claims 1 to 28 , wherein the acid leaching is conducted at a temperature that is between 20 and 100 degrees Celsius.
30 . The method of any one of claims 1 to 29 , wherein step 1 b ) comprises leaching the black mass material using a leaching solution comprising sulfuric acid, whereby the PLS comprises lithium, phosphate, iron and sulfate.
31 . The method of claim 30 , wherein the wherein the acid leaching comprises leaching the black mass using a leaching solution having a pH of between about 0.5 and about 2.0.
32 . The method of claim 31 , wherein the leaching solution comprises an initial free acid concentration of between about 30 g/L and about 60 g/L.
33 . The method of any one of claims 1 to 32 , wherein the acid leaching is conducted for a residence time that is between about 2 hours and about 6 hours.
34 . The method of claim 33 , wherein the concentration of lithium in the PLS is greater than the concentrations of phosphate, and iron in the PLS.
35 . The method of claim 33 , wherein the acid leaching is conducted for a leaching residence time that is between about 2 hours and about 6 hours, and wherein the leaching solution is at a leaching temperature that is between about 15 degrees Celsius and about 80 degrees Celsius.
36 . The method of any one of claims 1 to 35 , further comprising concentrating the output solution by extracting at least some solvent from the output solution to produce a concentrated output solution having a fourth concentration of lithium (wt %) that is greater than the third concentration of lithium.
37 . The method of any one of claims 1 to 36 , wherein the black mass material comprises at least 1.5%/wt lithium.
38 . The method of claim 37 , wherein the black mass material comprises less than about 10% wt lithium.
39 . The method of claim 38 , wherein the black mass material comprises about 3% wt lithium.
40 . The method of any one of claims 1 to 39 , wherein the black mass material comprises at least 10%/wt iron.
41 . The method of claim 40 , wherein the black mass material comprises less than 70% wt iron, and
42 . The method of claim 41 , wherein the black mass material comprises about 18% wt iron.
43 . The method of any one of claims 1 to 42 , wherein the black mass material comprises at least 5%/wt phosphorous.
44 . The method of claim 43 , wherein the black mass material comprises less than about 40% wt phosphorous.
45 . The method of claim 43 or 44 , wherein the black mass material comprises less than about 10% wt phosphorous.
46 . The method of any one of claims 1 to 45 , wherein the output solution comprises calcium and further comprising extracting substantially all of the calcium from the output solution to provide a calcium-depleted material stream comprising at least lithium and sodium.
47 . The method of claim 46 , wherein the extracting substantially all of the calcium from the output solution comprises a carbonate precipitation process via which more than 95% of the calcium is precipitated out of the output solution.
48 . The method of claim 47 , further comprising adding a sodium carbonate precipitating agent at a ratio of about 1.25× the stoichiometric concentration of calcium in the output solution.
49 . The method of claim 46 , wherein the carbonate precipitation process is conducted at a pH that is less than 11, for a residence time that is between 0.5 and 4 hours and at a temperature that is between about 5 and about 80 degrees Celsius.
50 . The method of any one of claims 46 - 49 , further comprising extracting substantially all of the lithium from the calcium-depleted material stream to provide lithium-rich residue and a lithium-depleted stream comprising the sodium.
51 . The method of claim 50 , wherein extracting substantially all of the lithium from the calcium-depleted material stream comprises a carbonate precipitation process in which a Na 2 CO 3 solution was added to the calcium-depleted material stream at a ratio of 1.25 times the stoichiometric requirement to precipitate the lithium, whereby more than 80% of the lithium is precipitated out of the calcium-depleted material stream as the lithium-rich residue.
52 . The method of any one of claims 1 to 51 , further comprising prior to step 1 a ):
a) processing LFP battery materials in a comminuting apparatus comprising at least a first comminuting device that is submerged in an immersion liquid, thereby creating reduced-size battery materials and liberating electrolyte material and the black mass solids comprising anode and cathode powders from within the LFP battery materials and providing a sized-reduced feed stream comprising the reduced size battery materials and the black mass solids and electrolyte materials entrained within the immersion liquid; and
b) processing the size-reduced feed stream to obtain the black mass feed material that comprises the black mass solids and a retained portion of the immersion liquid having entrained electrolyte materials.
53 . The method of claim 52 , wherein the black mass feed material comprises less than about 20% wt of the immersion liquid having entrained electrolyte materials.
54 . The method of claim 52 or 53 , wherein step 52 b ) comprises treating the sized-reduced feed stream with a first separator that separates the sized-reduced feed stream into the black mass feed material and at least a first filtrate stream comprising a second portion of the immersion liquid having entrained electrolyte materials therein.
55 . The method of claim 54 , wherein the first separator comprises a liquid-solid filter and wherein the first filtrate stream passes through the liquid-solid filter and the black mass feed material comprises a filter cake material retained by the liquid-solid filter.