Sulphuric Acid Roasting of Nickel-Metal Hydride Cathode For Release Of Major Metals

Direct leaching of metals from matrices of industrial products with mild reagents is usually associated with low extraction due to the complexity involved in the design and production. The cathode of spent Nickel-Metal Hydride (NiMH) battery, which amount to only 16% of the battery, was used for the research. Pretreatment of the cathode of NiMH with sulphuric acid roasting for the release of nickel (Ni), cobalt (Co), and manganese (Mn) was studied. The effects of sulphuric acid concentrations in the range of 50 – 100% (v/v), heat roasting temperature in the range 150 – 300 °C, and time of heating in the range 0.5 – 3 h were investigated. The roasted sample was dissolved in water; the amount of metal released was analysed to determine the efficiency of the roasting. With 1 mL of 100% sulphuric acid, the percentages of Ni, Co and Mn released were 98, 96 and 93%, respectively. Two hours thirty minutesthirty mintesof heating released 95% of Ni, 93% of Co and 90% of Mn at 275 °C. The sulphuric acid treatment effectively leached the metals into water. The method used in this research is highly effective in hydrometallurgical process for economic recovery critical metals from spent NiMH batteries