Abstract: A method for cleaning a flue gas containing flyash, sulfur dioxide and other contaminants includes providing a slurry source having a slurry of primarily water, magnesium sulfite and magnesium hydroxide along with small quantities of magnesium sulfate and magnesium chloride. The flyash is first removed from the flue gas and the flue gas is sprayed with the slurry for forming reaction products in the flue gas. The reaction products are then collected from the flue gas and a first portion of the reaction products is provided to the slurry source. A remaining portion of the reaction products is heated for decomposing into sulfur dioxide and magnesium oxide. The magnesium oxide is then provided to the slurry source. Magnesium sulfate and magnesium chloride are purged from the slurry source.