Separation And Recovery Of Magnesium And Calcium From Simulated Desulfurization Wastewater In Power Plant

The method of using CO2 for separation and recovery of calcium and magnesium from desulfurization wastewater was studied, and the optimum conditions of the two-stage process were explored. In the first stage, CO2 was used for the separation of calcium and magnesium in the desulfurization wastewater, 80% of the calcium in the desulfurization wastewater can be precipitated. The optimum temperature for the process was 30 degrees C; the optimum pH of calcium and magnesium separation was about 7.0. As for desulfurization wastewater with different contents of calcium and magnesium, the efficiency of calcium and magnesium separation was different. When the concentration ratio of calcium and magnesium was more than 1:4, the separation efficiency could basically meet the requirements of subsequent wastewater treatment. In the second stage, NaOH was added for magnesium recovery, the content of Mg(OH)(2) in the precipitate could reach 85%. The purity of magnesium in the precipitates increased rapidly before pH reached 10, and stabilized at pH 11.0. Under the optimal conditions, the removal rate of calcium and magnesium could reach 90% and 85%, respectively. This research results provide experimental reference and theoretical basis for the use of CO2 for the recovery of calcium and magnesium in desulfurization wastewater.