Experimental Study On Solidification Of Medical Waste Incinerator Fly Ash By Mixing With Asphalt

The property of fly ash from two different medical waste incinerators and effect of asphalt solidification in a city of Sichuan are studied in this paper. Leaching characteristics of heavy metal in fly ash and influence of heavy metal leaching at different factors such as leaching time,L/S ratio and pH value are studied. The results show that the content of heavy metals in the fly ash can increase with the decrease of particle size. Leaching ratio of heavy metals can increase with the increase of leaching time and L/S ratio. Heavy metals in the fly ash are very easy to leach in acid condition, while hardly leach in alkaline condition.Base on it, solidification characteristics of two kinds of fly ash are studied by using asphalt as solidification. Influence of heavy metals leaching is analyzed in different mixed proportions such as 10%,20%,30%,40% so that appropriate parameter on solidification of fly ash with asphalt is determined. The results show that leaching ratio and leaching consistence of heavy metals in solidified products can increase with increase of the content of fly ash. Appropriate ratio of two different kinds of fly ash in mixed proportions should be 40% and 30% respectively because of leaching characteristics of heavy metal.It is considered that additives such as Na₂S and so on are added in the mixtures of fly ash and asphalt so as to arrive better solidification/stabilization effect. Influence of heavy metals leaching is researched at different adding amount of several kinds of additives after solidification of fly ash with asphalt and stabilization effect in additives of same adding amount. The results show that leaching ratio of heavy metals in solidified products is low than the additives are not added in solidified products. The best stabilization effect of heavy metals in solidified products is Na₂S. The adding amount of the additive should be appropriate, generally about 3% because of stabilization effect and economic benefits.The above research findings offer valuable references to the further study and engineering application of asphalt solidification.