Solid-phase partitioning of mercury in artisanal gold mine tailings from selected key areas in Mindanao, Philippines, and its implications for mercury detoxification

Abstract

The solid-phase partitioning of mercury could provide necessary data in the identification of remediation techniques in contaminated artisanal gold mine tailings. This study was conducted to determine the total mercury content of mine wastes and identify its solid-phase partitioning through selective sequential extraction coupled with cold vapor atomic absorption spectroscopy. Samples from mine tailings and carbon-in-pulp (CIP) process were obtained from selected key areas in Mindanao, Philippines. The results showed that mercury use is still prevalent among small-scale gold miners in the Philippines. Tailings after ball mill-gravity concentration (W-BM and Li-BM samples) from Mt.Diwata and Libona contained high levels of mercury amounting to 25 and 6.5 mg/kg, respectively.The most prevalent form of mercury in the mine tailings was elemental/amalgamated mercury, followed by water soluble, exchangeable, organic, and strongly-bound phases, respectively. In contrast, mercury content of CIP residues were significantly lower at only 0.3 and 0.06 mg/kg for P-CIP (Del Pilar) and W-CIP (Mt. Diwata), respectively. The bulk of mercury in P-CIP samples was partitioned in residual fraction while in W-CIP sample, water soluble mercury predominated. Overall, this study has several important implications with regards to mercury detoxification of contaminated mine tailings from Mindanao, Philippines.

Solid-phase partitioning and release-retention mechanisms of copper, lead, zinc and arsenic in soils impacted by artisanal and small-scale gold mining (ASGM) activities

“…In the first step, the ores are crushed and Au is recovered via conventional gravity separation-amalgamation while in the second step, tailings from the first step are ground in make-shift ball mills and then fed to an improvised carbon-in-pulp (CIP) circuit (Aseniero et al, 2019;Veiga et al, 2014). The final tailings after CIP are then disposed of in shallow 'pits' close to the processing plant, which readily overflows during the wet season (Opiso et al, 2018).…”

“…ASGM activities are one of the primary cause of Hg contamination of the soil in many developing countries. In Mindanao, Philippines, for example, Opiso et al (2018) reported concentrations of elemental Hg up to~25 mg/kg in tailings of ASGM operations in four key areas that are, unfortunately, dumped or spread close to the processing areas without treatment. Similar studies of extensive Hg contamination due to ASGM activities have also been reported in Brazil, China, Colombia, Ghana, Ecuador, Indonesia, Mongolia, Peru, Suriname, Tanzania, Venezuela, and Zimbabwe (Babut et al, 2003;Cordy et al, 2011;Male et al, 2013;Mol et al, 2001;Steckling et al, 2011;Swain et al, 2007;Van Straaten, 2000).…”

“…ASGM activities are one of the primary cause of Hg contamination of the soil in many developing countries. In Mindanao, Philippines, for example, Opiso et al. (2018) reported concentrations of elemental Hg up to ∼25 mg/kg in tailings of ASGM operations in four key areas that are, unfortunately, dumped or spread close to the processing areas without treatment.…”

Improved pyrolysis behavior of ammonium polyphosphate-melamine-expandable (APP-MEL-EG) intumescent fire retardant coating system using ceria and dolomite as additives for I-beam steel application

“…In this study, a novel and more effective IFR coating using inorganic additives is proposed and its thermal protection performance on an Ibeam steel substrate was evaluated. Ceria and dolomite were selected because the former is a known waste from glassmaking industries (Tabelin et al, 2013(Tabelin et al, , 2018 while the latter is ubiquitous in limestone quarries (Eang et al, 2018a, b), sediments (Huyen et al, 2019a, b;Mar et al, 2013), waste rocks (Tabelin et al, 2012a, b;, 2017a and tailings of many gold mines (Aseniero et al, 2019;Opiso et al, 2018;Park et al, 2019). In addition to their beneficial use in the construction industry, finding value in these waste materials would also be good to the environment as a result of waste reduction for disposal from the glassmaking and mining industries.…”

Historical mercury losses from the gold mines of Victoria, Australia

“…Elemental mercury in legacy mine tailings also presents risks to the environment and human health (Ashe, 2012;Kim and Jung, 2012;Martin et al, 2016;Pearce et al, 2010;Slowley et al, 2005), with recent studies focussing on soil and plant bioremediation of miningrelated mercury contamination (e.g. Alcantara et al, 2017;Chasanah et al, 2018;Opiso et al, 2018). Australia has tens of thousands of legacy mine sites (Unger et al, 2012), many of which are almost certain to include mercury-contaminated tailings.…”