Taking the fly ash of a grate type municipal solid wastes （MSW） incinerator in our country as example

the effusion behavior of heavy metals

namely Pb

Zn

Ni

Cr

Cd and Cu etc.

under different pH and L/S of fly ash for MSW incineration has been studied

having brought into light the rule governing the effusion behavior of heavy metals in fly ash of MSW incineration. The results show that: （1） under acid condition

the concentration of heavy metals in fly ash increases gradually along with the reduction of pH

but at the time of pH<2

the effusion concentration of heavy metals is basically not changed; （2） under alkali condition

the effusion concentration of heavy metals is comparatively small

at pH>12

the heavy metals almost haven’t effusion

or effusion being very small; （3） the amount of heavy metals effusion in fly ash increases along with increment of L/S

at the time of L/S reaching a certain level

the heavy metals effusion almost being never changed again.