| 摘要 |
PURPOSE: A reducing method of sludge discharged from neutralization process of acid washing wastewater of stainless steel is provided, which can reutilize the waste from steel work and reduce consumption of hydrated lime and discharge amount of sludge. CONSTITUTION: The method comprises as follows: (i) dip waste containing line and magnesium in water and agitate for at least 5 min.; (ii) extract the supernatant which contains lime and magnesium and the pH of which is more than 10; and (iii) neutralize Fe(NO3)2, Ni(NO3)2, Cr(NO3)3, F- and No3- containing wastewater that is discharged from acid washing of stainless steel with the extracted solution to separate solution in which calcium nitrate is dissolved; and (iv) discharge the precipitates of FeOOH, Ni(OH)2, Cr(OH)3, CaF2 residue as sludge.
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