• 한국지하수토양환경학회지:지하수토양환경
• /
• 제16권5호
• /
• pp.31-41
• /
• 2011

The objectives of this study were to investigate the efficiencies of the stabilizers such as mono-potassium phosphate (MKP), phosphate fertilizer and red mud in treating the mine tailings contaminated with heavy metals and to characterize the changes in fractionations of the heavy metals during the stabilization. The TCLP results showed that the stabilization efficiencies of Cd, Pb and Zn increased with the increase in the stabilizer dosage and the reaction times. MKP showed the highest efficiencies for the heavy metals stabilization among the stabilizers tested. When the mine tailings were amended with MKP, the TCLP concentrations of Cd, Pb and Zn were reduced by 79~97%, 61~84%, and 89~99%, respectively. When the composite stabilizers, MKP/phosphate fertilizer or MKP/red mud, were used, the stabilization efficiencies were lower than when MKP was used as a single stabilizer. The sequential extraction results showed that carbonates fraction of Cd and Zn increased generally. Especially, when red mud was used, carbonates fraction of Cd and Zn increased 5 and 18 times, respectively. In the case of Pb, the treatment with MKP increased residual fraction by 10 times. The results showed that MKP was the most effective in stabilizing the heavy metals (Cd, Pb and Zn) to improve the efficacy of the composite binders.

• Geomechanics and Engineering
• /
• 제36권6호
• /
• pp.619-629
• /
• 2024

To improve the utilization rate of phosphate tailings (PTs) and widen the sources of subgrade filler, the PTs is employed to modify clay, forming a PTs modified clay, applied in the subgrade. Accordingly, the environmental friendliness of PTs was investigated. Subsequently, an optimal proportion was determined through compaction and California Bearing Ratio (CBR) experiments. Afterward, the stability of mixture with the optimal proportion was further evaluated through the water stability and dry-wet stability experiments. Finally, via the gradation and microstructure experiments, the strength mechanism of PTs modified clay was analyzed. The results show that the PTs were classified in the non-hazardous solid wastes, belonging to Class A building materials. With the increase of PTs content and the decrease of clay content, the optimum water content and the swelling degree gradually decrease, while the maximum dry density and CBR first increase and then decrease, reaching their peak value at 50% PTs content, which is the optimal proportion. The resilient modulus of PTs modified clay at the optimal proportion reaches 110.2 MPa. The water stability coefficient becomes stable after soaking for 4 days, while the dry-wet stability coefficient decreases with the increase of cycles and tends to be stable after 8 cycles. Under the long-term action, the dry-wet change has a greater adverse impact than continuous soaking. The analysis demonstrates that the better strength mainly comes from the skeleton role of PTs and the cementation of clay. The systematic laboratory test results and economic analysis collectively provide data evidence for the advantages of PTs modified clay as a subgrade filler.

• 대한환경공학회지
• /
• 제36권1호
• /
• pp.67-73
• /
• 2014

본 연구에서는 토양세척기법으로 1차 처리한 광미에 제거되지 않고 남아있는 중금속을 인산염을 이용해서 안정화하였다. 광미에 잔류하는 오염물질 농도는 As (1,861 mg/kg), Cd (20 mg/kg), Cu (56 mg/kg), Pb (2,149 mg/kg), Zn (633 mg/kg)이었다. 안정화제로는 $CaHPO_4$, $Ca(H_2PO_4)_2{\cdot}H_2O$, hydroxyapatite를 사용하였고, 안정화제의 첨가량은 0.1 wt%, 1 wt%, 10 wt%, 안정화 기간은 1, 3, 5, 7, 14일로 조절하였다. 세 가지 안정화제 모두 효율이 높았지만, 그 중에서 $Ca(H_2PO_4)_2{\cdot}H_2O$의 효율이 가장 높았고 첨가량은 1 wt%가 적당했다. 안정화 기간에 따른 효율차이는 크지 않았다. 1 wt% $Ca(H_2PO_4)_2{\cdot}H_2O$를 사용해서 1일 동안 안정화처리를 한 경우, TCLP 용출액의 비소와 중금속 농도는 As (0.328 mg/L), Cd (0.250 mg/L), Cu (0.143 mg/L), Pb (0.359 mg/L), Zn (2.622 mg/L)로 모두 각각의 RCRA-TCLP 기준치 이하로 나타나 안정성이 있는 것으로 평가되었다.

• 자원리싸이클링
• /
• 제23권5호
• /
• pp.55-61
• /
• 2014

As의 평균함량이 285 mg/kg인 상동광산 광물찌꺼기의 As제거를 위한 부유선별에서 인산염 첨가에 따른 영향을 알아보기 위해 제3인산나트륨(이하 T.S.P)을 분산제로 첨가하여 부유선별을 실시하였다. 먼저 분산제 없이 부유선별을 진행한 결과, As제거율은 88.7%, 부상물의 무게비는 2.52%였고 추가적으로 T.S.P를 첨가하여 부유선별을 실시한 결과 각각 92.74%, 2.26%로 As제거율은 증가하고 부상물의 무게비는 감소하였다. 두 실험의 부상물을 대상으로 입도분석을 진행한 결과, T.S.P를 첨가하지 않은 부상물은 평균입도가 19.34 um, 10 um이하의 양이 전체의 40.2%인 반면 T.S.P를 첨가할 경우, 각각 176.8 um, 6.5%였으며 이를 통해 미립입자의 부유가 억제되었음을 확인하였다. 또한 X.R.F 분석을 통해 두 실험 부상물의 실리카($SiO_2$)함량을 비교해본 결과, T.S.P를 첨가하지 않은 경우 42.74%, 첨가한 부상물의 경우 29.56%로 실리카계열의 친수성입자가 효과적으로 분산되어 부유가 억제되는 결과를 확인하였다.