Format

Send to

Choose Destination
Waste Manag. 2018 Jan;71:381-389. doi: 10.1016/j.wasman.2017.10.031. Epub 2017 Oct 27.

Lanthanide-alkali double sulfate precipitation from strong sulfuric acid NiMH battery waste leachate.

Author information

1
Aalto University, School of Chemical Engineering, Department of Chemical and Metallurgical Engineering, P.O. Box 16200, Aalto 00076, Finland.
2
Aalto University, School of Chemical Engineering, Department of Chemical and Metallurgical Engineering, P.O. Box 16200, Aalto 00076, Finland. Electronic address: mari.lundstrom@aalto.fi.

Abstract

In NiMH battery leaching, rare earth element (REE) precipitation from sulfate media is often reported as being a result of increasing pH of the pregnant leach solution (PLS). Here we demonstrate that this precipitation is a phenomenon that depends on both Na+ and SO42- concentrations and not solely on pH. A two-stage leaching for industrially crushed NiMH waste is performed: The first stage consists of H2SO4 leaching (2 M H2SO4, L/S = 10.4, V = 104 ml, T = 30 °C) and the second stage of H2O leaching (V = 100 ml, T = 25 °C). Moreover, precipitation experiments are separately performed as a function of added Na2SO4 and H2SO4. During the precipitation, higher than stoichiometric quantities of Na to REE are utilized and this increase in both precipitation reagent concentrations results in an improved double sulfate precipitation efficiency. The best REE precipitation efficiencies (98-99%) - achieved by increasing concentrations of H2SO4 and Na2SO4 by 1.59 M and 0.35 M, respectively - results in a 21.8 times Na (as Na2SO4) and 58.3 times SO4 change in stoichiometric ratio to REE. Results strongly indicate a straightforward approach for REE recovery from NiMH battery waste without the need to increase the pH of PLS.

KEYWORDS:

Double sulfate; Hydrometallurgy; Nickel metal hydride battery; Rare earths; Recycling

PMID:
29110941
DOI:
10.1016/j.wasman.2017.10.031
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center