PROCESS FOR RECOVERING RARE EARTHS AND METALS

Exhausted magnets recovery Hydrometallurgical process Liquid-solid discharge Neodymium

INTRODUCTION

The present invention concerns a hydrometallurgical process whose main purpose is the recovery of the materials that make up the exhausted permanent magnets; in particular the elements belonging to the group of rare earths such as Neodymium and Praseodymium and metals such as, among others, Iron and Nickel from Neodymium magnets.

TECHNICAL FEATURES

As the technique progresses, many commercial products, such as Hard Disk drives and audio products (microphones, loudspeakers, etc.), which contain magnets are replaced by new generations of products, posing a problem of disposing of Magnetic components. To date, the exhausted permanent magnets are mostly destined for landfill disposal. However, the need to reduce environmental contamination and conserve primary resources, has given rise to various mechanical, pyro and hydrometallurgical recovery technologies. As demonstrated by scientific literature, hydrometallurgical procedures are preferable to pyrometallurgical ones. The main disadvantage of hydrometallurgical processes, however, is the production of large quantities of solid and liquid waste that have a negative impact on the environment and human health if not properly disposed of. In this context, a team of researchers from the University of L’Aquila has developed an innovative process that allows the recovery of the above mentioned elements, not requiring significant quantities of costly chemical agents, nor hazardous wastes, in solid form and/or liquid, thus giving rise to an ecological and economic process.

POSSIBLE APPLICATIONS

Recovery and recycling of industrial waste from:
Electrical and electronic industry;
Chemical and ceramic industry (Nd based catalysts);
Automotive industry (permanent magnets and nickel metal hydride batteries).

ADVANTAGES

Process more economical and environmentally sustainable than the ones currently in use;
High recovery rate (over 95%) of Neodymium, Praseodymium, Nickel and Iron compared to the quantities present in the source material;
Easy industrialisation.

PROCESS FOR RECOVERING RARE EARTHS AND METALS

PROCESS FOR RECOVERING RARE EARTHS AND METALS

Treatment of secondary/waste to recover rare earth metals (REMs) is gaining importance due to its increasing global demand, lack of availability of high grade natural resources and huge generation of secondaries. Present paper reports the critical review on available processes for recovery of REMs from secondaries viz. manufacturing scraps, e-waste, industrial residues such as red mud, fly ash, waste water, etc. Hydrometallurgical processes with combination of Beneficiation/Pyro-/Electro techniques are discussed to recover REMs effectively. The recommended processes require less energy to deliver high purity yield which is one step towards green environment. Salient findings on various methods are reported with recommendations which will be helpful to researchers working in the area of REMs extraction.

Rare earth metals (REMs) are a series of 17 elements that have widespread and unique applications in high technology, power generation, communications, and defense industries. These resources are also pivotal to emergent sustainable energy and carbon alternative technologies. Recovery of REMs is interesting due to its high market prices along with various industrial applications. Conventional technologies, viz. precipitation, filtration, liquid-liquid extraction, solid-liquid extraction, ion exchange, super critical extraction, electrowinning, electrorefining, electroslag refining, etc., which have been developed for the recovery of REMs, are not economically attractive. Biosorption represents a biotechnological innovation as well as a cost effective excellent tool for the recovery of rare earth metals from aqueous solutions. A variety of biomaterials such as algae, fungi, bacteria, resin, activated carbon, etc., have been reported to serve as potential adsorbents for the recovery of REMs. The metal binding mechanisms, as well as the parameters influencing the uptake of rare earth metals and isotherm modeling are presented here. This article provides an overview of past achievements and current scenario of the biosorption studies carried out using some promising biosorbents which could serve as an economical means for recovering REMs. The experimental findings reported by different workers will provide insights into this research frontier.

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