METHOD OF CONTROLLING CHEMICAL IN WET DECARBURIZATION OF FLY ASH

摘要

In removing unburned carbon from fly ash by wet flotation, the amount of a foaming agent to be used is reduced to attain a reduction in chemical cost and the fly ash is prevented from decreasing in activity index. A method for the wet decarburization of fly ash is provided which comprises: adding water to the fly ash to form a slurry; adding a hydrophobizing agent and a foaming agent to the slurry; stirring the mixture to generate bubbles; causing unburned carbon contained in the fly ash to adhere to the bubbles and float therewith; and removing the unburned carbon from the fly ash. The sediment resulting from the wet flotation separation is taken out by solid-liquid separation, and the liquid phase obtained is reused in the flotation separation of fresh fly ash. In the reuse, the amount of the foaming agent to be added to the slurry is regulated so that the liquid phase has a foaming agent concentration in a given range. For regulating the concentration of the foaming agent in the liquid phase to a value in the given range, a method may be used in which the liquid phase is examined for COD and the amount of the foaming agent to be added to the slurry is regulated so that the COD comes to be in a given range.