Study on the process of aluminum removal and recovery from waste lithium ion batteries

As the main products of battery market, lithium ion batteries enjoy a high production, yet each year, the number of spent lithium ion batteries, though still rich in metal elements, is frightening. In order to effectively extract valuable metal elements from waste lithium ion batteries, this paper studies aluminium removal and recovery. In this experiment, NaOH was used as the leaching reagent and the secondary counter-current alkali dissolution method was also employed to explore optimal conditions for removing aluminium from these waste batteries. Besides, their elements and the surface morphology of aluminium hydroxide precipitation were analyzed by XRF and scanning electron microscopy, respectively. The effects of different pH on the recovery of aluminium hydroxide in the leachate were preliminarily investigated. The results show that appropriate conditions for removing aluminium include: the amount of alkali 1.5 times the stoichiometric ratio of Al, reaction temperature of 80 ℃, reaction time of 1h, primary solid-to-liquid ratio of 1:12, 5 % of alkali concentration in the secondary alkali leaching, the distribution ratio of alkali amount in primary and secondary alkali leaching of 6:4. In addition, feeding method is first adding alkali solution and then solid scrap in the first alkali leaching yet the feeding process is opposite to the second alkali leaching. Under these conditions, the dissolution rate of aluminium is above 12.32 %, with more than 90 % of it dissolved in the waste so that the optimum pH for the precipitation of aluminium hydroxide is 7~8.