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    Gold ore characterisation, mercury use & value chains analysis of the artisanal & small-scale gold mining sector of Wau, Morobe Province, Papua New Guinea : thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Earth Science, Massey University, Palmerston North, New Zealand. EMBARGO PENDING.
    (Massey University, 2018) Lucas Ponyalou, Olive Kimale
    Wau, in the Morobe Province of Papua New Guinea (PNG), is a rural township with a growing artisanal and small-scale gold mining (ASGM) sector working with mercury (Hg). It was once the centre of gold mining activities for European prospectors and companies between the 1930s and the late 1980s. Mercury amalgamation is used globally for gold extraction in the ASGM industry but was banned by the Minamata Convention in 2013 due to its toxicity to human beings. Miners and their families in Wau are exposed to Hg contamination during the amalgamation and retorting of the Au-Hg amalgam. The Mineral Resources Authority (MRA) regulates the PNG mining industry using the Mining Act 1992 and the Mining Safety Act 1997. Gravity concentration and mercury amalgamation are gold recovery techniques used in the ASGM sector of Wau. Cyanidation, a common technique for processing free-milling Au and AuAg grains less than 0.2 mm in size, is largely used in the corporate mining sector but has not been used within the ASGM sector of PNG. The purpose of this research is to halt the use of mercury in Wau through an improved understanding of its gold ore characteristics. Hence, a study into the economic value chains system, gold grade distribution and ore characterisation was conducted on nine selected ASGM sites located throughout the Namie and Kaindi prospects in Wau. Although modestly profitable, all sites excluded the fundamental practices of grade control and ore characterisation, which are vital to the mining value chain. Comminution, also an important step for liberating gold, was only practised at one mine site. The average gold grades of the nine sites ranged from 0.06 to 5.45 mg/kg Au with the primary mineralization of Kaindi containing higher gold grades than the secondary deposits of Namie. The main gold minerals observed in the scanning electron microscope (SEM) include native Au and electrum AuAg with a predominant grain size of less than 0.07 mm. Mercury amalgamation is only useful on gold crystals with a grain size of 0.07-1.5 mm. Hylander et al. (2007) discovered that mercury will not efficiently amalgamate gold particles less than 0.07 mm. In addition, mercury amalgamation is only useful on free-milling, liberated native gold but will not recover gold that is attached to or encapsulated within other minerals. This suggests that the Wau miners are losing fine-grained gold less than 0.07 mm or any gold that is insufficiently liberated as waste or tailings. This was confirmed in the tailings sample from Site 1 which had numerous fine-grained Au measuring less than 0.07 mm. Thus, cyanidation would be the appropriate technique to process the gold mineral type (Au and AuAg) and gold grain size observed in most sites in Wau. Cyanidation after comminution are steps that must be included in the Wau ASGM value chain in order to optimize the recovery of the dominantly fine-grained Au.
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    Entanglements and disentanglements : a posthuman approach to mercury use in artisanal and small-scale gold mining in Antioquia, Colombia : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Social Anthropology at Massey University, Palmerston North, New Zealand
    (Massey University, 2016) Robertson, Thomas Jonathan
    This research uses qualitative research techniques and posthuman theories to investigate the dynamic relationship between artisanal and small-scale gold miners and mercury in the context of Antioquia, Colombia. This is done to contribute to understandings of, and inform potential solutions for, the global environmental problem that is mercury pollution from artisanal and small-scale gold mining (ASGM). Miners come to know mercury through practices, and through these practices, mercury comes to be co-constitutive of an informal ASGM industry. Mercury provides an easy yet profitable mode of gold extraction with limited capital expenditure. Eliminating the use of mercury means a re-constitution of ASGM as a formal industry with higher levels of capital investment, new actors and a shift to a more representational approach to knowing materials. The use of toxic mercury and an increase in the enforcement of mining legislation are framing miners as illegal. Formal, responsible mining is becoming a dominant reality, and informal miners who resent being labelled illegal are working to transition to this reality. Miners’ experiences of this transition vary greatly, and this variation can be explored through the lens of ecological habitus. Many miners are using mercury elimination to perform good citizenship by mining responsibly, introducing a performative aspect to formalisation. Nevertheless, miners still face significant challenges to formalisation. As a result, many miners have had to become subcontractors for large-scale mining companies, entering exploitative relationships with which mercury, through its absence, is complicit. Taking this approach towards understanding the relationship between miners and mercury has helped to resolve the conflict between material and social deterministic views of the practice of mercury use, and linked mercury to a wider political context, which is a necessary consideration for a collaborative approach with miners to eliminate mercury. Keywords: Artisanal and small-scale gold mining; ASGM; mercury; Colombia; anthropology; posthumanism; entanglements; politics of materiality; performativity; informality.