Abstract:

Typically mining operations use total carbon (C) measurements for assessment of carbonate neutralisation potential in the block and mining model. The objective of this study was to develop a low cost, rapid, industry-applicable, thermal decomposition methodology for quantification of carbonate mineral acid neutralisation capacity (RapT ANC) to aid in the prediction, prevention and remediation of acid mine drainage from waste rock, tailings, and other mined materials. Standard titration-based methods, when used with the objective of assessing only carbonate ANC, can be compromised due to contributions from silicate minerals and ion exchange, erroneous contributions from Fe-containing carbonate minerals, and interference from graphite and organic carbon. The methodology developed consists of decomposition of non-neutralising carbonate minerals in a N₂ atmosphere at 500°C followed by carbon assay of the residue. RapT ANC (kg H₂SO₄ t^-1) is then calculated as RapT ANC = C_neutralising (wt%) × 81.8, where C_neutralising (wt%) = C_residue (wt%) × (weight of residue in g)/(weight of initial sample in g). This method provides a rapid and cost-effective means to analyse for carbonate neutralisation potential.Typically mining operations use total carbon (C) measurements for assessment of carbonate neutralisation potential in the block and mining model. The objective of this study was to develop a low cost, rapid, industry-applicable, thermal decomposition methodology for quantification of carbonate mineral acid neutralisation capacity (RapT ANC) to aid in the prediction, prevention and remediation of acid mine drainage from waste rock, tailings, and other mined materials. Standard titration-based methods, when used with the objective of assessing only carbonate ANC, can be compromised due to contributions from silicate minerals and ion exchange, erroneous contributions from Fe-containing carbonate minerals, and interference from graphite and organic carbon. The methodology developed consists of decomposition of non-neutralising carbonate minerals in a N₂ atmosphere at 500°C followed by carbon assay of the residue. RapT ANC (kg H₂SO₄ t^-1) is then calculated as RapT ANC = C_neutralising (wt%) × 81.8, where C_neutralising (wt%) = C_residue (wt%) × (weight of residue in g)/(weight of initial sample in g). This method provides a rapid and cost-effective means to analyse for carbonate neutralisation potential.

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Dr. Roger Smart