Study Of The Acid-seperation Method Characterizing The Slagging Characteristics Of Fly-ash Aluminumsilicates

Slagging of Coal-fired boilers bothered thermal power generating units a lot.Moreover,slagging mechanisms of boilers were mainly dominated by the liquid phases of aluminosilicates,and the maximum contents in the slag of coal-fired boilers were aluminosilicates,and it will deliver a comprehensive understanding and prediction on fly-ash deposition in coal-fired boilers to study the aluminosilicates matters which were easy to melt.Fly-ash was treated using hot hydrochloric acid,denoting it as acid seperation in short,and the solubility of aluminum et al was related to the slagging characteristics of aluminosilicates in fly-ash.In order to provide the scientific arguments on slagging tendency of practical fly-ash,we conducted the below experiments.The experiments on Daihai and Dingzhou fly-ash were conducted by changing the temperature,heating time and stirring conditions,and the three common metal elements,especially aluminum of the solutions were analyzed by ICP-AES method,and the XRD method was also used to analyze the phases in fly-ash and its residues after acid seperation.Moreover the27 Al Magic Angle Spinning nuclear magnetic resonance method was used to analyze the coordinates of Al in fly-ash,and explored the means about analyzing the nmr patterns.The results showed that the acid seperation has a good repeatability by comparing the two parrallel sets of samples.the dissolved aluminum contents in the two kinds of fly ash increased as the the temperature increased and the heating time accumulated,and reached the top when the temperature was 200°C and the heating time was 1 hour,and it will also be used as the very conditon for our future experiments.The shares of aluminum in Dingzhou ash was higher than that in Daihai ash,which was a good and stable index for indicating the relation between the slagging and dissolved contents of aluminum.XRD patterns showed that the crystal matters in the two kinds of fly ash did not change significantly before and after the acid seperation,and the non-crystal aluminosilicates that not be detected through XRD might affect the characteristics of slagging much.The NMR results showed that function Pearson IV might prevail on the aspect of curve simulation,but it kind of deviated from the practical situation on quantitative analysis.the aluminum coordinates in Daihai and Dingzhou fly-ash were different,which testified that there were distinctive differences on structures of the aluminosilicates in the two kinds of fly-ash distinctive differences.This provides the basis for the chemical structures of the aluminosilicates material in fly-ash to further develop the acid digestion method.