PRECIPITATION AND WASHING OF IRON PHOSPHATE FROM FERRONICKEL LEACH SOLUTION FOR PRODUCTION OF LITHIUM IRON PHOSPHATE BATTERY CATHODE PRECURSOR

• Main Author: Faiha Masykur, Zahra
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86342
• Institution: Institut Teknologi Bandung

Driven by the increasing electrification of transportation and the need for more efficient energy, the demand for batteries, a vital part of electric vehicles, has been increasing. Lithium-ion batteries (LIBs) are the most widely developed battery type for electric vehicles. One type of LIB is lithium iron phosphate (LiFePO4 or LFP), which uses iron phosphate (FePO4?2H2O) as a precursor material in its cathode. On the other hand, ferronickel (FeNi), a grade 2 nickel product, can be further processed to produce iron phosphate and nickel sulfate via hydrometallurgical processing. This research focuses on studying the synthesis of FePO4?2H2O as a raw material for LFP battery precursors production by precipitation method from an artificial solution that simulates the pregnant solution of FeNi leaching, followed by a precipitate washing process. A series of experiments were conducted to study the effect of pH and operating temperature on the Fe precipitation and co-precipitation of Ni, Co, Cr, and Mn during the iron phosphate precipitation process. The precipitation experiments used ammonium dihydrogen phosphate (NH4H2PO4) as the phosphorus source and sodium hydroxide (NaOH) as the pH regulator. Furthermore, washing experiments were carried out on iron phosphate precipitates obtained under optimum conditions with various types of washing agents, including sulfuric acid (H2SO4), hydrochloric acid (HCl), acetic acid (CH3COOH), and citric acid (C6H8O7), wash solution pH, operating temperature and washing time to study the possibility of separating Ni, Co, Cr, and Mn that co-precipitated with Fe. The present experimental results showed that increasing pH and precipitation temperature increased the rate of Fe precipitation and co-precipitation of Ni, Co, Cr, and Mn. The optimum condition in the precipitation process was obtained at pH of 1.8 and temperature of 80 ºC, which gave an Fe precipitation of 92.33% and Ni, Co, Cr, and Mn co-precipitations of 10.11%, 7.84%, 7.84%, and 49.37%, respectively. Under these conditions, precipitates with Fe = 22.02%, Ni = 0.43%, Co, = 0.01%, Cr = 0.33%, and Mn = 0.04% were produced. On the other hand, the optimum conditions in the iron phosphate washing process were obtained using HCl as the washing agent at a pH of 3.5 and leaching temperature of 25 ºC for 15 minutes, which gave a percent dissolution of Fe, Ni, Co, Cr, and Mn of 1.48%, 45.60%, 15.22%, 3.07%, and 7.46%, respectively. The precipitates at the optimum precipitation and washing stage conditions contained Fe = 24.73%, Ni = 0.26%, Co = 0.01%, Cr = 0.25%, and Mn = 0.03%. The results indicated that Ni, Co, Cr, and Mn are difficult to separate from Fe without causing high Fe loss by using HCl, H2SO4, CH3COOH, or C6H8O7 as washing agents.