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Dissection of the NAG pH test: tracking efficacy through examining reaction products

Parbhakar-Fox, A ORCID: 0000-0002-3570-1195, Fox, N, Ferguson, T, Hill, R and Maynard, B 2018 , 'Dissection of the NAG pH test: tracking efficacy through examining reaction products', in C Wolkersdorfer and L Sartz and A Weber and J Burgess and G Tremblay (eds.), Proceedings of the 11th International Conference on Acid Rock Drainage (2018: Pretoria, South Africa) International Mine Water Association WISA Mine Water Division , pp. 949-955 .

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Abstract

In this study we sought to better understand the mechanics of the NAG pH test and determine the influence each variable has in controlling the resulting NAG pH, a value which is commonly used by the mining industry for waste classification. Three bulk samples (20 kg) representative of waste types A (alkaline), B (weakly-NAF) and D (PAF) were obtained from the Savage River mine, Tasmania. Variables tested included initial reaction time, heating temperature, heating length, post reaction cooling time and hydrogen peroxide (H2O2) strength (n=126). Our observations showed that for this suite, a multi-addition NAG pH test facilitated efficient sulphide oxidation for low sulphidesulphur samples (i.e., 2O2 addition, heating to 80 to 90 °C for 2.5 hours, and then cooling of the reaction solution overnight with the NAG pH reading taken the following morning. This study demonstrated that using the recommended standard conditions given in Smart et al. (2002) is not appropriate for general use. Rather a suite of representative waste samples should initially be selected and the optimal conditions to facilitate sulphide oxidation determined on a site-per-site basis.

Item Type: Conference Publication
Authors/Creators:Parbhakar-Fox, A and Fox, N and Ferguson, T and Hill, R and Maynard, B
Keywords: acid mine drainage, waste management, sulphide, mining, mine planning
Journal or Publication Title: Proceedings of the 11th International Conference on Acid Rock Drainage (2018: Pretoria, South Africa) International Mine Water Association WISA Mine Water Division
Copyright Information:

Copyright 2018 IMWA - International Mine Water Association.

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