Experimental Study On Na₂O-K₂O-SiO₂-CaF₂ Molten Slag Under The Treatment Of Ultrasonic

Ultrasonic treatment has been widely used in wastewater treatment,cleaning,welding,medical and many other fields,this is mainly due to ultrasonic has the characteristics of easy to obtain large sound pressure,strong power density,sound energy concentration,and interac-tion between ultrasound and media produces a series of special physical and chemical effects,such as mechanical effects,cavitation effects,thermal effects.However the research and ap-plication in the field of metallurgy were still at the few,especially there was no report about ultrasonic used in slag system.In the present study,ultrasonic treatment is applied to slag system to examine the feasibility of ultrasonic treatment in molten slag and the influence of ultrasonic treatment on transformation of melt slag structure and physical properties,which lay the foundation for the potential application in metallurgical slag.After using ultrasound treatment to slag,the structure units of slag with higher degree of polymerization depolymerized into the ones with lower degree of polymerization,the slag which containing fluorine could generate[SiF6]2-,to further reduce the polymerization degree of molten slag.With the ultrasonic power increased,the non-bridging oxygen number(NBO/T)of melt slag increased from 2.4 to 2.8,the degree of polymerization of slag was gradually reducing.Under the same ultrasonic power condition,the slag which had the higher degree of polymerization and containing fluorine would reduce the degree of polymerization more obvious.Ultrasonic treatment could change the viscosity of the slag.At the same temperature,the viscosity of slag after ultrasonic treatment was lower than that without ultrasonic treatment.The greater the power was,the more the viscosity decreased.After stopping ultrasonic treat-ment,the slag viscosity would quickly return to the level of viscosity that not applied ultra-sonic treatment,which indicated that the structural units with low degree of polymerization in the slag could not exist stably.Using the same power of ultrasonic treatment,the original slag with higher degree of polymerization and containing fluorine,the magnitude of the viscosity reduction was larger than that of the slag with a lower degree of the original polymerization.Ultrasonic would cause the temperature rise of slag,which leads to the decrease of slag vis-cosity,but with the increase of ultrasonic power,the decrease of slag viscosity caused by the thermal effect of ultrasound was gradually weakened.Ultrasonic treatment could change the surface tension of slag.The stronger of the ultra-sonic power,the bigger transformation of surface tension is.But the transformation of surface tension for different components of the slag is not exactly the same,the surface tension of original slag with higher degree of polymerization and containing fluorine decreased with the increase of ultrasonic power,but the surface tension of slag without fluorine increased.Comparison of the effects of ultrasonic treatment on the transformation behavior of struc-ture,viscosity,surface tension of molten slag,there was a remarkable consistency between them,that the melt structure transition was the main factor of the change of viscosity and sur-face tension.This proved that ultrasonic treatment of molten slag could achieve the purpose of changing the melt structure and physical properties of molten slag,and also proved the fea-sibility of ultrasonic treatment of slag.