CCB-based encapsulation of pyrite for remediation of acid mine drainage.
Acid mine drainage (AMD) from abandoned coal mines continues to be one of the most significant environmental problems. Remediation of AMD requires an addition of lime source to decrease the acidity, and grouting the entire mine and encapsulating the pyrite by calcium-rich additives is often employed. Utilization of alkaline coal combustion by-products (CCBs) has gained acceptance in such remediation applications because of their cost-effectiveness. A study was conducted to investigate the effectiveness of CCBs to abate acid mine drainage by encapsulation of pyrite. Geomechanical, hydraulic, and environmental tests were performed on grouts prepared with various ratios of CCBs as well as an alternative free lime source, lime kiln dust (LKD). The results indicated that the mechanical properties of grouts were dependent on their free lime contents. Hydraulic conductivities of pyrite-grout columns were relatively high due to the coating of the pyrite rock with the grout rather than the filling of all of the void spaces, as commonly experienced in field applications. The leaching tests indicated that the presence of high amounts of lime in a grout is not solely sufficient to improve the quality of AMD, since the rate of dissolution of a high lime content grout may be slow due to its rapid hardening. Therefore, it is recommended that grouts be selected with consideration of their hardening capacities, as well as the percentage of lime content present in the mixture.
Bulusu
Sowmya
S
Geosyntec Consultants, Inc., 1255 Roberts Boulevard NW, Suite 200, Kennesaw, GA 30144, USA.
Aydilek
Ahmet H
AH
Rustagi
Neha
N
D000143:Acids / Q000032:analysis; D017610:Calcium Compounds / Q000032:analysis; D002244:Carbon / Q000032:analysis; D060729:Coal Ash; D003032:Coal Mining; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006801:Humans; D007220:Industrial Waste / Q000517:prevention & control*; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D010087:Oxides / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D013431:Sulfates / Q000032:analysis; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D000143:Acids; D017610:Calcium Compounds; D060729:Coal Ash; D007220:Industrial Waste; D010087:Oxides; D052638:Particulate Matter; D013431:Sulfates; D013440:Sulfides; D014874:Water Pollutants, Chemical; C011342:pyrite; D002244:Carbon; C016538:lime; D007501:Iron