A Controlled Low-Strength Materials (CLSM) is suitable for mine backfilling because it does not require compaction owing to it high fluidity and can be installed quickly. Therefore, a CLSM utilizing CO2-solidified Circulating Fluidzed Bed Combustion (CFBC) coal ash was developed and it’s properties were investigated, since. CO2-solidification of CFBC coal ash can inhibit exudation of heavy metals. The chemical composition and specific surface area of Pulverized coal Combustion fly ash and CFBC fly ash were analyzed. The water ratio, compressive strength and length change ratio of CLSM were confirmed. The water ratios differed with the specific surface area of the CLSM. It was confirmed that the porosity of CLSM affected its compressive strength and length change ratio.

In this study, an accelerated carbonation process was applied to stabilize hazardous heavy metals of industrial solid waste incineration (ISWI) bottom ash and fly ash, and to reduce CO2 emissions. The most commonly used method to stabilize heavy metals is accelerated carbonation using a high water-to-solid ratio including oxidation and carbonation reactions as well as neutralization of the pH, dissolution, and precipitation and sorption. This process has been recognized as having a significant effect on the leaching of heavy metals in alkaline materials such as ISWI ash. The accelerated carbonation process with CO2 absorption was investigated to confirm the leaching behavior of heavy metals contained in ISWI ash including fly and bottom ash. Only the temperature of the chamber at atmospheric pressure was varied and the CO2 concentration was kept constant at 99% while the water-to-solid ratio (L/S) was set at 0.3 and 3.0 dm3/kg. In the result, the concentration of leached heavy metals and pH value decreased with increasing carbonation reaction time whereas the bottom ash showed no effect. The mechanism of heavy metal stabilization is supported by two findings during the carbonation reaction. First, the carbonation reaction is sufficient to decrease the pH and to form an insoluble heavy metal-material that contributes to a reduction of the leaching. Second, the adsorbent compound in the bottom ash controls the leaching of heavy metals; the calcite formed by the carbonation reaction has high affinity of heavy metals. In addition, approximately 5 kg/ton and 27 kg/ton CO2 were sequestrated in ISWI bottom ash and fly ash after the carbonation reaction, respectively.

본 연구에서는 석탄 광산배수에 함유된 중금속을 부유선별로 제거하기에 앞서 부유선별 조건에 영향을 미치는 철, 망간, 알루미늄 이온의 침전특성을 알아보았다. Fe(III), Mn(II), Al(III) 이온을 NaOH와 반응시켜 1 h 동안 침전시키면 Fe(III)은 pH 5.0 이상에서, Mn(II)은 pH 10.0 이상에서 그리고 Al(III)은 pH 6.0~9.0의 범위에서 대부분 침전되어 여액에 1.0mgL-1 이하로 잔류되었다. Fe(III), Mn(II), Al(III)의 혼합 용액에 포수제인 올레인산나트륨을 첨가하였을 경우, 각각의 중금속 이온은 올레인산나트륨과 반응하여 불용성 염을 거의 형성하지 않았기 때문에 침전 부선법으로 광산배수에 함유된 중금속을 제거해야 하는 것으로 나타났다.