Nickel-metal hydride (NiMH) battery recycling
Recycling of nickel-metal hydride (NiMH) batteries extracts substantially pure nickel based on adding a leach agent to granular cathode material resulting from agitation of the NiMH batteries to form a leach solution. A pH of the leach solution is maintained for precipitating iron, aluminum and lanthanide rare earth elements (REE) for yielding a nickel solution for forming a cathode material precursor in a recycled battery, often with a high nickel content.
1 . A method of recycling nickel-metal hydride (NiMH) batteries, comprising:
combining a leach agent and granular cathode material resulting from agitation of the NiMH batteries to form a leach solution; and
adjusting or maintaining a pH of the leach solution to between 5 and 6 for precipitating and removing impurities comprising iron, aluminum and lanthanide rare earth elements (REE) for yielding a nickel solution.
2 . The method of claim 1 wherein the leach agent comprises sulfuric acid.
3 . The method of claim 2 wherein the leach agent further comprises hydrogen peroxide.
4 . The method of claim 1 wherein the pH of the leach solution is adjusted to between 0 and 3 for removing the REEs.
5 . The method of claim 1 wherein the granular cathode material is comingled with casing, current collectors and anode material in a black mass.
6 . The method of claim 1 wherein the yielded nickel solution has a nickel ion concentration in a range between 1.1 M-1.7 M.
7 . The method of claim 1 wherein the lanthanide rare earth elements include La, Ce, Pr and Nd.
8 . The method of claim 1 further comprising:
receiving a recycling stream including the NiMH batteries; and
agitating the batteries to generate the granular cathode material.
9 . The method of claim 1 further comprising forming a cathode material precursor from the nickel solution.
10 . A method of recycling nickel-metal hydride (NiMH) batteries, comprising:
combining a leach agent and granular cathode material resulting from agitation of the NiMH batteries to form a leach solution;
adjusting or maintaining a pH of the leach solution for precipitating impurities comprising iron, aluminum and lanthanide rare earth elements (REE) for yielding a nickel solution;
stirring the leach solution for at least 5 hours for dissolving nickel and cobalt in the leach solution;
following dissolution of the nickel and cobalt, adjusting or maintaining the pH of the leach solution between 5 and 6 for precipitating Fe and Al; and
filtering precipitated impurities including the Fe and Al for recovering the dissolved nickel and cobalt in the leach solution.
11 . The method of claim 10 further comprising, after filtering the precipitated impurities,
reducing the pH to between 0-3 for precipitating the lanthanide elements; and
filtering the lanthanide rare earth elements as a sodium double sulfate salt.
12 . The method of claim 10 further comprising, after filtering the precipitated impurities,
adding at least one of sulfuric acid and sodium hydroxide for adjusting sodium ions to a molar ratio of 15-25 with the lanthanide rare earth elements and SO 4 to a molar ratio of 35-60 with the lanthanide rare earth elements; and
removing excess sodium sulfate.
13 . A method of recycling nickel-metal hydride (NiMH) batteries, comprising:
receiving a black mass in a recycling stream including granular cathode material resulting from agitation of the NiMH batteries;
adding sulfuric acid of a 2-5 M concentration to the black mass to form a leach solution;
adding hydrogen peroxide in an amount of 0.2-0.6 volume ratio to the weight of black mass to the leach solution;
stirring the leach solution for at least 5 hours while maintaining a pH of the leach solution between 5-6 for precipitating impurities including iron and aluminum from the leach solution;
filtering the leach solution to remove precipitated solid of the impurities;
adding sulfuric acid of a concentration between 93%-98% and sodium hydroxide of a concentration between 25%-50% to adjust the pH of the leach solution between 1-3 for precipitating REEs (rare earth elements) remaining in the leach solution;
precipitating a double sulfate salt of the REEs as a crystalline powder;
filtering the REEs from the leach solution; and
crystallizing excess sodium sulfate to achieve a nickel ion concentration between 1.1 M-1.7 M in the leach solution.