A Study on Reducing pH and Hardness of Washing Solution of Fly Ash in Cement Plant

Abstract

In order to dispose the washing solution of municipal solid waste incinerator (MSWI) fly ash with high hardness and high pH value by mechanical vapor recompression (MVR) process, the method to reducing hardness and pH value was studied in this article. The results show that the hardness of the washing solution will be reduced with the pH value increased by adding liquid caustic soda. And the optimum adding quantity of liquid caustic soda is to adjust the hardness to 1000mg/L while the pH value will be adjusted to about 12.90. And the pH value of the washing solution with the hardness is 1000mg/L can be reduced to 9-10 by adding enough carbon dioxide, and then the hardness of the washing solution will be reduced to less than 100mg/L. And then the washing solution can be disposed by MVR process.