Kinetic Regularities and Mathematical Modelling of Potassium Chloride Dissolution

The dissolution process of potassium chloride particles in the apparatus with two-blade mechanical stirrer was investigated and the mass transfer coefficient was determined. The experimental results were generalized by criterion dependence. The independence of the mass transfer coefficient from the solid particles diameter was confirmed. A countercurrent process of potassium salt dissolution in two apparatuses with a mechanical stirring was considered. A mathematical model for countercurrent dissolution was developed and the efficiency of this process was determined.

Recovery of Cobalt from Spent Lithium-Ion Mobile Phone Batteries Using Liquid–Liquid Extraction

The aim of this paper was to propose and test a continuous cobalt recovery process from waste mobile phone batteries. The procedure started with dismantling, crushing, and classifying the materials. A study on leaching with sulfuric acid and hydrogen peroxide was carried out with subsequent selective separation of cobalt by means of liquid–liquid extraction. The best extraction conditions were determined based on a sequence of experiments that consisted of selecting the best extractant for cobalt, then assessing the impact of extractant concentration, pH, and contact time on the extraction yield. With these conditions, an extraction isotherm was obtained and correlated with a mathematical model to define the number of extraction stages for a countercurrent process using the McCabe–Thiele method. Then, a similar study was done for stripping conditions and, as a last step, cobalt electroplating was performed. The proposed process offers a solution for the treatment of these batteries, avoiding potential problems of contamination and risk for living beings, as well as offering an opportunity to recover valuable metal.