Recycling of spent nickel-cadmium battery using a thermal separation process

Spent batteries, which contain many hazardous metals, may lead to secondary pollution if not properly treated. Nickel-cadmium (Ni-Cd) batteries contain a large amount of valuable metals that are worth recovery. They are mainly composed of a positive electrode (33.3%), a negative electrode (28.8%), and a metal can (14.5%). The main composition of the positive electrode and negative electrode are Ni (304,000 mg/kg) and Cd (531,000 mg/kg), respectively. The other components are mainly composed of Fe. In this study, a thermal separation process (TSP) was used to recover valuable metals from spent Ni-Cd batteries with limestone and cullet additives. After the TSP, the output-materials were divided into slag, ingot, and flue gas. The slag was mainly composed of Ca and Si, and the major crystalline phase was CaSiO3. The slag was verified to be a nonhazardous material using a toxicity characteristics leaching procedure and could thus be recycled. The ingot had a high level of Fe (514,000 mg/kg) and Ni (245,000 mg/kg), so it could be refined to recover the Ni or directly serve as an additive in the making of steel. The particulate phase of the flue gas contained high levels of Cd (686,000 mg/kg) and Zn (36,000 mg/kg) and could be refined to recover Cd. (c) 2017 American Institute of Chemical Engineers Environ Prog, 37: 645-654, 2018