Plasma technology is international advanced technology to destroy various types of hazardous wastes.The vitrified slag can form in the process of plasma treatment of inorganic wastes and effectively fix heavy metals

and its leaching rate is very low.Explained the formation mechanism of vitrified slag using the concept of silicon-oxygen ratio

and verified by experiment.Concluded that the vitrified slag can form at silicon-oxygen ratio less than 3

and crystal will grow at silicon-oxygen ratio more than 3.Find out the most important factors among 7 factors

including silicon-oxygen ratio

basicity

heavy metal contents

temperature

treating time

fly-ash types and constituents

to the heavy metal fixed efficiency using a 30 kW DC plasma arc reactor system.Concluded that the temperature and the heavy metal contents are the most important factors and directly influenced the heavy metal As

Pb and Zn fixed efficiency

the other 5 factors little effect on the heavy metal fixed efficiency.With increasing temperature

the heavy metal fixed efficiency dropped.As the heavy metal contents increases

the heavy metal fixed efficiency increased and then decreased before

and reached a maximum value at 6mg·g-1.But all of 7 factors didn’t effect to the metal Cr fixed efficiency

the heavy metal Cr fixed efficiency are more than 85% in all experiments.The heavy metal fixed process is divided into 4 stages depend on the temperature of crucibles wall heated.80% of escape heavy metal run away at volatilization period which last 6—10 minutes from heat beginning.So how to control the heavy metals running away at volatilization period is the best way to improve the heavy metals fixed efficiency.