Browsing by Author "Broadhurst J L"

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    Biokinetic test for the characterisation of AMD generation potential of sulfide mineral wastes
    (Elsevier, 2010) Hesketh, A H; Broadhurst J L; Bryan, C G; van Hille, R P; Harrison, S T L  
    Acid mine drainage (AMD) is formed by the microbially catalysed oxidation of sulfide minerals on exposure to moisture and air. It results in the ongoing contamination of water streams with acidity, sulfate and metal ions in solution, limiting subsequent use of the water without its remediation. AMD prevention is a key requirement for meeting mine closure standards and AMD prediction plays an integral role in waste management and AMD prevention. However, both the static and kinetic tests used currently have shortfalls, including only providing a worst case scenario, providing limited kinetic data, particularly with respect to microbial catalysis or requiring an excessive time frame for the provision of useful data. In this study, we review biological tests reported to predict AMD generation potential and propose an extension to these tests in the form of a biokinetic test. The proposed test provides information on the potential and likelihood of acidification upon microbial colonisation as well as the relative kinetics of the acid-consuming and acid-producing reactions. This provides more meaningful data than static tests, within a reasonable timeframe. Experiments performed to evaluate the biokinetic test, using copper sulfide flotation tailings, show results consistent with those of traditional static tests. However, these also provide additional kinetic information that could help to inform management strategies.
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    Mitigating acid rock drainage risks while recovering low-sulfur coal from ultrafine colliery wastes using froth flotation
    (Elsevier, 2012) Mbamba, C Kazadi; Harrison, S T L; Franzidis, J-P; Broadhurst J L
    Ultrafine coal wastes contain sulfide minerals, particularly pyrite, which oxidize and give rise to acid rock drainage (ARD) resulting in extensive and prolonged contamination of local ground and surface waters. Currently, mining operations emphasise an end-of-pipe approach to ARD management using costly chemical or biological treatment techniques, which do not address the long term problem of achieving sustainable closure solutions within the resource lifetime. Eliminating ARD potential before waste disposal would have a major beneficial impact on water quality and facilitate long term closure solutions. Recovering a saleable coal product would be an added economic incentive. This paper presents the results of an investigation to establish the feasibility of a two-stage flotation process to produce: (i) a low-volume sulfide-rich concentrate, (ii) a high-volume benign (low sulfur) tailings, and (iii) a coal concentrate. Laboratory-scale batch flotation experiments were carried out using an oily collector to float coal from samples of coal ultrafines and a xanthate collector to recover acid-generating sulfides. The results of acid generating potential tests (both static and biokinetic) indicate that a low-sulfur tailings with low ARD potential may be produced, together with a coal ultrafine concentrate stream with a low ash content.