DBPapers
DOI: 10.5593/SGEM2014/B42/S18.009

EFFECTIVENESS OF EGGSHELL RESIDUES MIXED WITH ALKALINE AMENDMENTS IN ACID MINE DRAINAGE REMEDIATION

A. Kastyuchik, A. Karam,M. Aider,A . Jaouich
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-16-2 / ISSN 1314-2704, June 19-25, 2014, Book 4, Vol. 2, 65-72 pp

ABSTRACT
Liming is a prerequisite for sustainable stabilization and neutralization of acid -
producing sulphide mine tailings. Lime is a compound of calcium or calcium and
magnesium capable of neutralizing acid compounds in the soil. A laboratory experiment was conducted to investigate the possibility of utilizing chicken eggshells alone or mixed with five alkaline materials as a liming material on acidic sulphide mine tailing (SMT). Samples of air-dried SMT (pH 3.3) were treated with chicken eggshells (CES) alone or in combination with concrete residue rich in calcareous products (Portland cement) (CCM), dolomitic limestone (DOL), calcitic limestone (CAL) and magnesium oxide (MGO). The treatments were as follows: SMT without neutralizing agents; 1, 2, 4, 8 and 10% CES alone or in combination with 1 and 2% CCM, 1 and 2% MGO, 1 and 2% DOL or 1 and 2% CAL; 1, 2, 4, 8 and 10% CCM; 1 and 2% CAL; 1 and 2% DOL; 1 and 2% MGO. Acid tailing neutralization experiment was carried out by mixing 10.0 g of treated tailing samples with 25 ml of double distilled water. The tailing suspensions were allowed to equilibrate for 70 d at room temperature with occasional shaking. Tailing suspension pH (pHTS) was measured after 1 h, 7 d, 14 d, 21 d, 35 d, 56 d, and 70 d. Each treatment was replicated two times. Application of the highest rate of CES (10%) alone increased pHTS from 2.61 (control) to 7.24 in 70 days. However, when adding 2% of cement or 2% MGO to the CES-amended tailing, pHTS values increased from 7.24 (10% CES) to 8.78 or 8.54, respectively. The increase in pHTS was generally greater for tailing samples receiving CCM alone (pH 8.35-11.52). The lowest pHTS was obtained with CES-treated tailings (7.18-7.24). CES mixed with CCM or MGO are more efficient in maintaining alkaline conditions (pHTS > 8) in the tailing than CES + CAL or CES + DOL, due probably to the higher neutralizing capacity of magnesium oxide and cement. Aluminum, copper, iron, manganese and zinc were not detected in aqueous suspensions of treated-tailing samples, due probably to their chemical precipitation. These results may have practical implications in tailing management for the reduction of acid generation and trace metal mobility in sulphide mine drainage system and of water contamination risk. Alternative liming materials such as cement and magnesium oxide mixed with eggshells may be used as a calcitic amendment to neutralize acid-producing mine tailings.

Keywords: amendment, neutralization, pH, waste reuse, liming materials.
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