Green industrial scale production of inorganic artificial stone from low calorific value coal ashes enhanced by physical resonant activation

Abstract

Low calorific value coal fly ash and boiler slag with low silicon and aluminum content, low cementitious activity, is difficult to be large-scale applications. In this study, pilot and industrial scale tests were conducted to recycle low calorific value coal fly ash and boiler slag for the preparation of high valuable inorganic artificial stone, the activity of fly ash and boiler slag was activated by physical resonance without chemical activation. From the pilot test, it was determined that artificial stones enhanced by resonant activation behaved the higher compression strength of 75.35 MPa with 80 wt% fly ash and boiler slag utilization, which was about 45.18% increase in compression strength compared with that of conventional static agitation. The resonant activation agitation promoted the hydration reaction between fly ash and cement, generating more fibrous dense C-S-H gels. Afterword, 40 tons of raw materials were used to produce artificial stones, whose compression strength reached as high as 100.42 MPa. The whole production process was simple and pollution free, with solid waste utilization up to 80 wt%, creating a value of 160–170 US $/t. Hence, low calorific value coal fly ash and boiler slag have been realized in scale, high value and green application.