A geochemical examination of humidity cell tests

Maest, Ann S.; Nordstrom, D. Kirk

doi:10.1016/j.apgeochem.2017.03.016

Cited by 41 publications

(26 citation statements)

References 47 publications

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“…Whilst the manual ARDI represents the front line in assessing ARD potential in drill core, and should continue to do so with an awareness of its subjective limitations, complementary datasets collected by drill core scanning technologies should be used to assess and validate ARDI results. This will improve deposit-wide characterization for comparison with mineralogical datasets, which provide accurate quantification of the reactive acid-forming and primary neutralizing phases [28], and will show strong classification agreement between both datasets (e.g., ARDI contributing to the refinement of NAF classifications); hence, indicating its robust nature for geoenvironmental domaining. Ultimately, it should be used to complement other geoenvironmental domaining indexes developed specifically for drill core analyses to improve early environmental forecasting and contribute to improve mine-planning activities.…”

Section: Discussionmentioning

confidence: 96%

Automated Acid Rock Drainage Indexing from Drill Core Imagery

et al. 2018

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The automated classification of acid rock drainage (ARD) potential developed in this study is based on a manual ARD Index (ARDI) logging code. Several components of the ARDI require accurate identification of sulfide minerals that hyperspectral drill core scanning technologies cannot yet report. To overcome this, a new methodology was developed that uses red–green–blue (RGB) true color images generated by Corescan® to determine the presence or absence of sulfides using supervised classification. The output images were then recombined with Corescan® visible to near infrared-shortwave infrared (VNIR-SWIR) mineral classifications to obtain information that allowed an automated ARDI (A-ARDI) assessment to be performed. To test this, A-ARDI estimations and the resulting acid-forming potential classifications for 22 drill core samples obtained from a porphyry Cu–Au deposit were compared to ARDI classifications made from manual observations and geochemical and mineralogical analyses. Results indicated overall agreement between automated and manual ARD potential classifications and those from geochemical and mineralogical analyses. Major differences between manual and automated ARDI results were a function of differences in estimates of sulfide and neutralizer mineral concentrations, likely due to the subjective nature of manual estimates of mineral content and automated classification image resolution limitations. The automated approach presented here for the classification of ARD potential offers rapid and repeatable outcomes that complement manual and analyses derived classifications. Methods for automated ARD classification from digital drill core data represent a step-change for geoenvironmental management practices in the mining industry.

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Section: Discussionmentioning

confidence: 96%

Automated Acid Rock Drainage Indexing from Drill Core Imagery

et al. 2018

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“…6A) seems to indicate that humidity cells are a good reflection of the field when considering sulfur-cycling taxa. Microbial communities in these kinetic tests are also an important consideration because microorganisms can impact rock weathering rates (51). For example, under extremely acidic conditions, microorganisms can dramatically accelerate sulfide mineral oxidation, and rates can change based on microbial biomass (52) and the composition of the microbial community (37).…”

Section: Discussionmentioning

confidence: 99%

Novel Microbial Assemblages Dominate Weathered Sulfide-Bearing Rock from Copper-Nickel Deposits in the Duluth Complex, Minnesota, USA

Jones

Lapakko

Wenz

et al. 2017

Appl Environ Microbiol

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The Duluth Complex in northeastern Minnesota hosts economically significant deposits of copper, nickel, and platinum group elements (PGEs). The primary sulfide mineralogy of these deposits includes the minerals pyrrhotite, chalcopyrite, pentlandite, and cubanite, and weathering experiments show that most sulfidebearing rock from the Duluth Complex generates moderately acidic leachate (pH 4 to 6). Microorganisms are important catalysts for metal sulfide oxidation and could influence the quality of water from mines in the Duluth Complex. Nevertheless, compared with that of extremely acidic environments, much less is known about the microbial ecology of moderately acidic sulfide-bearing mine waste, and so existing information may have little relevance to those microorganisms catalyzing oxidation reactions in the Duluth Complex. Here, we characterized the microbial communities in decade-long weathering experiments (kinetic tests) conducted on crushed rock and tailings from the Duluth Complex. Analyses of 16S rRNA genes and transcripts showed that differences among microbial communities correspond to pH, rock type, and experimental treatment. Moreover, microbial communities from the weathered Duluth Complex rock were dominated by taxa that are not typically associated with acidic mine waste. The most abundant operational taxonomic units (OTUs) were from the genera Meiothermus and Sulfuriferula, as well as from diverse clades of uncultivated Chloroflexi, Acidobacteria, and Betaproteobacteria. Specific taxa, including putative sulfur-oxidizing Sulfuriferula spp., appeared to be primarily associated with Duluth Complex rock, but not pyrite-bearing rocks subjected to the same experimental treatment. We discuss the implications of these results for the microbial ecology of moderately acidic mine waste with low sulfide content, as well as for kinetic testing of mine waste.IMPORTANCE Economic sulfide mineral deposits in the Duluth Complex may represent the largest undeveloped source of copper and nickel on Earth. Microorganisms are important catalysts for sulfide mineral oxidation, and research on extreme acidophiles has improved our ability to manage and remediate mine wastes. We found that the microbial assemblages associated with weathered rock from the Duluth Complex are dominated by organisms not widely associated with mine waste or mining-impacted environments, and we describe geochemical and experimental influences on community composition. This report will be a useful foundation for understanding the microbial biogeochemistry of moderately acidic mine waste from these and similar deposits.

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“…Mining can be considered a waste-management industry (Lottermoser 2010). Indeed, large volumes of material must be processed to extract a relatively small volume of the commodities of interest.…”

Section: Introductionmentioning

confidence: 99%

Guidance for the Integrated Use of Hydrological, Geochemical, and Isotopic Tools in Mining Operations

et al. 2020

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This paper summarizes international state-of-the-art applications and opportunities for employing and deploying hydrological, geochemical, and isotopic tools in an integrated manner for investigations of mining operations. It is intended to aid formulation of more integrated approaches for evaluating the overall sustainability of mining projects. The focus is particularly on mine waters, including: environmental water sources, mine water dynamics, and as a source and vector for pollution in the wider environment. The guidance is generic to mining projects and not just reflective of a particular extraction (e.g. coal, metalliferous, uranium) industry. A mine life cycle perspective has been adopted to highlight the potential for more integrated investigations at each stage of a mining operation. Three types of mines have been considered: new (i.e. those in the planning stage), active (i.e. working mines), and historical mines (i.e. inactive and abandoned mines). The practical usage of geochemical analyses and isotopic studies described here emphasise characterisation, dynamics, and process understanding for water quality considerations in tandem with water resource and environmental impact implications. Both environmental (i.e. ambient) and applied (i.e. injected) tracers are considered. This guide is written for scientists (including isotope specialists) who have limited or no mine water experience, environmental managers, planners, consultants, and regulators with key interests in planned, active, and legacy mining projects.

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A geochemical examination of humidity cell tests

Cited by 41 publications

References 47 publications

Automated Acid Rock Drainage Indexing from Drill Core Imagery

Automated Acid Rock Drainage Indexing from Drill Core Imagery

Novel Microbial Assemblages Dominate Weathered Sulfide-Bearing Rock from Copper-Nickel Deposits in the Duluth Complex, Minnesota, USA

Guidance for the Integrated Use of Hydrological, Geochemical, and Isotopic Tools in Mining Operations

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