Evaluation of Neutralization Potential Determinations for Metal Mine Waste and a Proposed Alternative

Abstract

Standard acid-base accounting (standard ABA), modified ABA, and B.C. Research initial static tests tended to overestimate the neutralization potential (NP) present as calcium carbonate and magnesium carbonate, with the extent of overestimation depending on the minerals present in the 10 metal-mine wastes examined. For 6 of the 10 samples the static test NP values were within about 10 kg/mt CaC0 3 of the calculated mineralogic NP. These samples were composed largely of qua1tz and sheet silicates (mica, chlorite, kaolinite, montrnorillonite). The excess acid neutralization measured for these samples was apparently due to the presence of some (less than 10 % ) calcium feldspar in the samples. For the standard ABA and modified ABA methods, the NP overestimation was higher (13 to 47 kg/mt CaC0 3 ) for samples containing larger amounts of calcium feldspar, pyroxene, olivine, or iron carbonate minerals. The extent of overestimation for the B.C. Research initial NP was typically slightly higher than the standard ABA and modified ABA and was greatest for samples containing iron carbonate. The maximum overestimations by the standard ABA, modified ABA, and B.C. Research initial test NP values were 33, 31, and 49 kg/mt CaC0 3 , respectively. A newly proposed method of NP determination, NP available above pH 6, was more accurate than these three methods. Six of the 10 NP values determined by this method were approximately equal to the mineralogic NP values. For the remaining 4 samples, this NP was within 3 kg/mt CaC0 3 of the mineralogic NP. Additional

In Situ Effectiveness of Alkaline and Cementitious Amendments to Stabilize Oxidized Acid-Generating Tailings

“…The leachates from the amended cells were characterized by circumneutral pH values and were less charged with chemical species than the control cell, except in the case of Ca, which was released more from cell C5 (5 wt % OPC) (Summary of chemical analysis is presented in Table S1). In fact, the dissolution of carbonates and OPC produces alkalinity and buffers the pH of leachates [11,15,31,38,[57][58][59][70][71][72][73][74][75][76][77][78][79]. The pH was established early, due to high dissolution rates of limestone and cement in the acidic media.…”

Prediction of the effects of acid mine drainage on variations in the hydrogeochemical environment at sulfide-bearing ore deposits

“…(6) LAPAKKO PROCEDURE FOR DETERMI NATION ON NEUTRALIZING POTENTIAL OF METAL MINE WASTE (Lapakko, 1994) is a modifi cation of the BC RESEARCH INC. INITIAL TEST PROCEDURE and includes crushing to 325 mesh and titration with acid to pH 6.0 instead of 3.5.…”

Revue de littérature détaillée sur les tests statiques et les essais cinétiques comme outils de prédiction du drainage minier acide

“…Le PA est calculé plus facilement en utilisant le soufre total de l'échantillon (déterminé par analyse chimique) et en le multipliant par un coefficient stoechiométrique de 31,25 (Tableau 2). Lawrence et Wang (1997) ont suggéré une modification du test de Sobek et al (1978) en utilisant la même mé-thodologie sans toutefois bouillir l'échantillon ce qui éviterait une surestimation du PN causée par le chauffage de l'échantil-lon et qui ferait réagir des minéraux relativement réfractaires (silicates comme les plagioclases, les pyroxènes et les olivines, Lapakko 1994;Frostad et al 2003) qui ne réagiraient pas dans les conditions naturelles comme sur un site minier. Dans la méthode de Lawrence et Wang (1997), on ajoute nettement moins d'acide à l'échantillon et en plusieurs étapes (à 0h, 2h et après 22h) afin de garder le pH de la pulpe entre 2,0 et 2,5.…”

“…Le Tableau 3 résume les principales approches. Kwong (1993), Lapakko (1994), Li (1997), Lawrence et Scheske (1997), et Paktunc (1999a et Bouzahzah (2013a) proposent des calculs basés sur la somme des contributions individuelles de chaque minéral dans la production de l'acidité et sa neutralisation donnant ainsi, selon ces auteurs, une estimation plus juste des PA et PN. Lapakko (1994) propose un calcul du PN très simple basé sur la participation de la calcite et la magnésite assumant qu'elles sont seules responsables de la neutralisation.…”