Basic Study on Removing Unburnt Carbon from Fly Ash by Ore Flotation to Use as Concrete Admixture

When we use fly ash as a concrete admixture, unburnt carbon in fly ash can’t be ignore. Many quantities of unburnt carbon in fly ash inhibit air entraining performance and fluidity of flesh concrete. In this study, we made a device to remove unburnt carbon from fly ash by ore flotation and checked the performance of the device by experiments. The conclusions are as follows, it was clarified that to remove unburnt carbon, the method which circulated water was more effective than the method which didn’t circulate water. The element of the tail ash was not too different from an untreated ash except for the decrease of unburnt carbon. The pH of tail ash was lower as compared with that of untreated ash. Compressive strength of mortal contained tail ash was equivalent to that of mortal contained fly ash which was able to use without being treated.