Abstract:Address to high operation cost and large energy consumption of magnesium sulfate wastewater treatment process by concentrated crystallization, lime neutralization was used to treat magnesium sulfate wastewater. The effects of lime dosage, reaction time and reaction temperature on concentration of calcium magnesium ions and sulfate radical in wastewater were studied. The results show that under the conditions of reaction temperature of 20 ℃, lime dosage of 70—80 g, and reaction time of 2 h, SO42- concentration in magnesium sulfate wastewater can be reduced from 33.24 g/L to 10 g/L below (removal rates of 81.68%), MgO concentration can be reduced from 24.6 g/L to 15 g/L below (removal rates of 47.20%), and CaO concentration can be kept 2.6 g/L below. The neutralization filtrate is reused for roasting ore leaching process, leaching rate of rare earth is 93.76% under the conditions of leaching temperature of 20—30 ℃ and L/S=8. The main components of reaction neutralization residue are CaSO4?2H2O and Mg(OH)2, which can be reused to prepare calcium sulfate whiskers.