ABSTRACT
Selective dismantling of spent alkaline batteries was conducted, followed by neutral leaching of the black mass at room temperature and gravity concentration to recover KOH and metallic Zn, respectively. A counter current washing process at two different S/L ratios of 1:3 and 1:5 was evaluated and a Wilfley shaking table was employed aiming metallic Zn recovery. Neutral leaching could be effectively conducted at a 1:5 S/L ratio (17 rpm, 20 min, room temperature), using four cycles with fresh water, leading to less than 1% of the black mass K in the final water. Although less effective in terms of K recovery, the use of 1:5 S/L ratio or lower seems more technically feasible for future application of the methodic washing (34 g KOH/L in the washing water). Gravity concentration requires further optimization to effectively concentrate metallic Zn and Mn appears to be present in the fractions of higher caliber (>850μm).
