Recovery of Lithium as Li3PO4 from Waste Water in a LIB Recycling Process

This study was conducted to obtain engineering design data for a process to recover lithium in the form of Li3PO4 from the waste water of a lithium ion battery (LIB) recycling process. The influence of temperature, pH, and concentration on the solubility of Li3PO4 and the reaction rate in the Na3PO4-Li2SO4-H2O system was investigated. As a result, the solubility of Li3PO4, 372 mg/L, increased to 417 mg/L as the reaction temperature increased from 20 to 90 degrees C. At the same time, the reaction rate increased from 0.0174 x 10(-4) to 2.32 x 10(-4) mol/L.s. The yield of lithium phosphate rises in proportion to increases in the concentration of salt, temperature and pH, in the reaction of 3Li(2)SO(4) + 2Na(3)PO(4) -> 2Li(3)PO(4) + 3Na(2)SO(4). That is, the higher the concentration, temperature and pH solution are, the more Li3PO4 precipitates. The temperature must be 70 degrees C or higher to obtain 90% or more Li3PO4 as a precipitate. The lithium phosphate particle formed at 20 degrees C are composed of secondary particles or their agglomerate, which is composed of primary particles of 0.01 mu m or less size. The size of the primary particle becomes bigger when the reaction temperature is raised and at 90 degrees C it becomes a large columnar particle, with a 10 similar to 20 mu m length and 5 similar to 10 mu m breadth.