Paper Title
Transforming Waste Ni-Mh Battery Electrodes to Nickel Based Alloys By Novel and Sustainable Pyrometallurgical Recycling Methods

Abstract
Recovery of valuable metals such as nickel, and synthesis of alloys (Ni-Co and Fe-Ni) from waste Nickel-metal hydride (Ni-MH) batteries is a major area of focus and interest in this present work. Novel, green, and sustainable techniques, such as combination of two waste streams (e-waste plastics as a potential carbon source and waste Ni-MH batteries) and hydrogen plasma smelting were adopted to synthesize industry grade nickel-cobalt alloy and ferro-nickel alloy. Reduction of nickel oxide present in waste Ni-MH battery, using e-waste plastic, facilitated 99% nickel-cobalt alloy with ICP-OES and XPS analysis corroborating the results. Usage of e-waste plastic, as a potential alternative to conventional carbon, observes the gas-based reduction of nickel oxide. Hydrogen plasma smelting of nickel oxide in a maintained reducing ambience of argon and hydrogen flow rate (1:1) experiences the rapid reduction reaction (1800-2000°C), duly complemented by three forms of hydrogen (atomic, molecular, and ionic). The formation of ferro-nickel occurs within 15 min with Fe (66 wt%), Ni (31 wt %) and Co (2%) that are close to the industry standard. Moreover, hydrogen plasma smelting pushes rare earth elements (present in cathode of Ni-MH battery) to slag phase (La: 24 wt%, Ce: 11 wt%, and Nd: 7 wt%) in the form of oxides without contaminating the product phase. Characterisation analysis of product and slag phase were performed using XRD and ICP-OES techniques. These scientific recovery techniques put forth a promising eco-friendly and sustainable solution to utilise waste resources in a befitting way, thus recovering valuable metals and alloys and safeguarding the environment at the same time. Index Terms— waste Ni-MH battery, sustainability, hydrogen plasma, nickel alloy, e-waste plastic