Steel Slag as Neutralization-Adsorption Material for Treatment of Acidic Zn~(2+)-Containing Wastewater

摘要

Chemical and mineral compositions, the surface morphology of steel slag were evaluated in this study. On this basis, treatment effect of acidic Zn~(2+)-containing wastewater was investigated using the slag as a water treatment material, and then mechanism of removal Zn~(2+) was discussed. The results showed steel slag was a suitable material for treatment of acidic heavy mental wastewater. Under conditions of slag size fraction of -1.2+0.15mm, slag concentration of 30 g-L~(-1), stirring speed of 150rpm for 30 min, removal rate of Zn~(2+) was 98.59%, Zn~(2+) concentration in wastewater was reduced from 100 mg/L to 1.41 mg/L, and pH value was increased from 2 to 6.4. Filtrate after treatment reached the first discharge standard in integrated wastewater discharge standard (GB8978-1996). Appearance of Zn (OH)_2 diffraction peaks in XRD pattern showed that Zn (OH)_2 had covered on steel slag surface, and Zn~(2+) removal included four main processes: production of OH" from hydration reaction of active calcium silicate in steel slag, generation of Zn (OH)_2 precipitation in wastewater, adsorption and settlement of Zn (OH)_2 on surface of steel slag and removal of Zn (OH)_2 from wastewater by filtration.