The objective of this study is to investigate the removal characteristics and evaluate the treatment feasibility of heavy metals and sulfate ion from acid mine drainage(AMD) by porous zeolite-slag(PZS) ceramics, to which wood flour was added for the foaming of calcined mixtures of natural zeolite and converter slag.
The mixing ratio of zeolite to slag adequate for maximum removal of heavy metals was shown to be 1:1~1:3. The optimal calcination temperature and time range of ZS ceramics for removal of heavy metals in AMD was measured to be 600∼800℃ and 2 hours, respectively. The removal efficiency of heavy metals was increased as the weight ratio of wood flour to PZS ceramics increased. The 10wt% of wood flour to PZS ceramics significantly enhanced the removal efficiency of heavy metals and sulfate ion in AMD, resulting from increased specific surface area of PZS ceramics. The particle size of wood flour had little effect on the removal of heavy metals in AMD by PZS ceramics.
The column reactor system test showed that the spherical PZS ceramics had high feasibility as a media for removal of heavy metals and suflate ion in AMD. The 24 hours of hydraulic retention time(HRT) condition and 1:3 mixing ratio of zeolite to slag were appropriate for the treatment of AMD. The average removal efficiencies of heavy metals and sulfate ion from AMD by spherical type PZS ceramics with 1:3 (Z:S) mixing ratio in column reactor system during 121 operating days under 24 hours of hydraulic retention time conditions were Al 97.5%, As 98.8%, Cd 86.1%, Cu 96.2%, Fe 99.7%, Mn 64.1%, Pb 97.2%, Zn 66.7% and SO42- 76.0%, respectively. The backwashing cycle in the column reactor system was operated to be 8.1 days.
The analysis results of mechanism showed that heavy metals could be dominantly eliminated by adsorption or ion-exchange in pH condition lower than the precipitation pH region and by precipitation or co-precipitation in pH condition higher than the precipitation pH region, suggesting that PZS ceramics could act as a multi-functional ceramics for the treatment of AMD by adsorption, ion-exchange and precipitation, co-precipitation.
The microscopic analysis using XRD exhibited that the major component of precipitated sludge was observed to be schwertmanite (Fe8O8(OH)6(SO4)). The EDS analysis showed that heavy metals in AMD could be eliminated by adsorption or ion-exchange.

Key words : Acid Mine Drainage, Heavy metals, Sulfate ion, Natural zeolite, Steel converter slag, Wood flour, Porous ceramics