Acidification of lead/zinc mine tailings and its effect on heavy metal mobility

Heavy metals content in acid mine drainage at abandoned and active mining area

“…Heavy metals content in Lubuk Mandi show lower reading since the sampling was carried out during rainy period. Rainy season contributed to the depletion of heavy metals from the AMD [25].…”

A Review of Static Tests and Recent Studies

“…Seven techniques are reviewed in this study, which determine the sample's maximum Acid Production Potential (APP) with its maximum Neutralization Potential (NP). These seven methods are (i) Acid-Base Accounting (ABA), (ii) Modified ABA (MABA), (iii) paste pH, (iv) Net Acid Generation (NAG), (v) Sequential NAG test (SNAG), (vi) Kinetic NAG test (KNAG) and (vii) Acid Buffering Characteristics Curve (ABCC) test (Ehinola and Adene, 2008;Komnitsas et al, 2009;Hesketh et al, 2010b;Huges et al, 2007;Miller et al, 1991;Pope et al, 2010;Shu et al, 2001;;Weber et al, 2004). Each test uses separate methods to evaluate the capacity for acid generation and neutralization.…”

“…To determine the NAG, 2.5 g of sample is oxidized by suspension in 250 mL of 15% (v/v) H 2 O 2 , placed inside a fume hood for 24 h and then boiled for 1 h. After cooling to ambient temperature, the final NAG pH is then measured and titrated using 0.1 mol/l NaOH to pH 4.5 and pH 7. The NAG is calculated in terms of kg H 2 SO 4 /t of sample (Shu et al, 2001). Commonly, a NAG pH of less than 4.5 indicates the sample is acid producing and the amount of acid is determined by back-titration and expressed in terms of kg H 2 SO 4 /t of sample, similar to the ABA technique.…”

Geochemical Application for Environmental Monitoring and Metal Mining Management

“…The acidity of solution under the NAG is a direct measurement of net acid generation of sample. Shu et al (2001) studied the effect of lead/zinc mine acidity on heavy metal mobility using both NAG test and ABA method. They concluded, based on their results that NAG test, direct measurements of ANC from acid produced from oxidized sulfide, yields more accurate than that of ABA method.…”