Spent NiMH batteries—The role of selective precipitation in the recovery of valuable metals

• Published in: Journal of power sources Vol. 193; no. 2; pp. 914 - 923
• Main Authors: Bertuol, Daniel Assumpção, Bernardes, Andréa Moura, Tenório, Jorge Alberto Soares
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.09.2009; Elsevier
• Subjects: Applied sciences; Batteries; Direct energy conversion and energy accumulation; Electric batteries; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Mathematical models; NiMH batteries; Precipitation; Rare earth metals; Rare earths; Recovery; Solvent extraction; Rare earths; Precipitation; NiMH batteries; Material recovery; Electronic equipment; Lanthanide; Nickel hydride; Secondary cell; Electrode material; Electric batteries; Solvent extraction; Cobalt; Sulfuric acid; Nickel; Recycling
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2009.05.014

The production of electronic equipment, such as computers and cell phones, and, consequently, batteries, has increased dramatically. One of the types of batteries whose production and consumption has increased in recent times is the nickel metal hydride (NiMH) battery. This study evaluated a hydrometallurgical method of recovery of rare earths and a simple method to obtain a solution rich in Ni–Co from spent NiMH batteries. The active materials from both electrodes were manually removed from the accumulators and leached. Several acid and basic solutions for the recovery of rare earths were evaluated. Results showed that more than 98 wt.% of the rare earths were recovered as sulfate salts by dissolution with sulfuric acid, followed by selective precipitation at pH 1.2 using sodium hydroxide. The complete process, precipitation at pH 1.2 followed by precipitation at pH 7, removed about 100 wt.% of iron and 70 wt.% of zinc from the leaching solution. Results were similar to those found in studies that used solvent extraction. This method is easy, economic, and does not pose environmental threats of solvent extraction.