Thursday, 16 May 2013

Adaptation of mineral processing techniques for recycling of lithium-ion and nickel metal hydride batteries

Production of lithium-ion (LiBs) and nickel metal hydride (NiMH) batteries is expected to increase rapidly due to the soaring price of oil and gas, which increases interest in renewable energy, as well as the introduction of hybrid vehicles and electric vehicles which use such batteries as an effective energy storage device (see also the posting of 20 June 2011).

Development of an efficient recycling scheme to recover the valuable parts and safely dispose the harmful ones at the end life of the batteries is a necessity. The challenge, however, is how to recover all the valuable metals without sacrificing the economics of the recycling process.

Several LiBs and NiMH battery recycling processes have been developed in recent years. A review of these processes and their development has been presented in a recently published paper in Minerals Engineering, which has become the 3rd highest downloaded paper over the past 3 months, highlighting the intense interest in recycling.

It was found that the major drawback of these recycling processes is the loss of some of the valuable battery parts, as the techniques were not originally developed for these types of batteries. Also, some of these processes are expensive and designed for specific types of batteries which ignore contamination of the recycling stream with impurities and other battery types.

Using mineral processing operations such as grinding, screening, magnetic, electrostatic, and gravity separations to liberate the electrodal materials and to concentrate valuable metals is a critical step in any recycling process. The review showed that applying these processes reduces the volume of LiBs and NiMH scrap, liberates their valuables, reduces the need for leachate purification in hydrometallurgical processes, and facilitates decomposition of the battery electrolyte. Based on these results a flowsheet to recycle mixed stream LiBs and NiMH battery scrap has been proposed.

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