Open-pit Gold Mine Research Articles

Information sources, awareness and preventive health behaviors in a population at risk of Arsenic exposure: The role of gender and social networks.

The population of Paracatu is at risk of Arsenic (As) exposure associated with long-term exploration of the largest open pit gold mine in Brazil. As part of the interdisciplinary research “The Paracatu project: Arsenic environmental contamination and human health risks assessment in Paracatu-MG”, carried out between 2011 and 2013, we used data disaggregated by gender to identify the sources of As-related information being accessed by inhabitants of Paracatu and to examine if access to these sources was correlated to awareness of As health effects and adoption of behaviors to reduce risk of As exposure. Semi-structured, face-to-face interviews were carried out with 460 participants (294 women and 166 men) to collect data on respondent’s socio-demographic characteristics, use of mass media and social communication networks as sources of information on As issues, the trustworthiness of these information sources, awareness of As health effects, and adoption of behaviors to reduce As exposure. For both men and women, interpersonal communication was used and trusted more frequently than mass media to obtain information on As. Discussion of As issues occurred preferentially among individuals of the same gender and was associated with awareness of As health risks. There are marked differences in variables correlated with the adoption of behaviors to reduce the risk of As exposure between men and women. Discussing As issues with women was associated with adoption of risk-reduction practices for both genders. In contrast, men who discuss As issues with other men were less likely to adopt As exposure prevention behaviors. Finally, adoption was associated with awareness of As health effects for women, but this was not the case for men. Policy implications for decision makers, practitioners and researchers are discussed, based on concrete examples of how gender-specific approaches can effectively guide the formulation and implementation of health promotion campaigns and programs.

NPV risk simulation of an open pit gold mine project under the O’Hara cost model by using GAs

This paper analyzes an open pit gold mine project based on the O’Hara cost model. Hypothetical data is proposed based on different authors that have studied open pit gold projects, and variations are proposed according to the probability distributions associated to key variables affecting the NPV, like production level, ore grade, price of ore, and others, so as to see what if, in a gold open pit mine project of 3000 metric tons per day of ore. Two case scenarios were analyzed to simulate the NPV, one where there is low certainty data available, and the other where the information available is of high certainty. Results based on genetic algorithm metaheuristic simulations, which combine basically Montecarlo simulations provided by the Palisade Risk software, the O’Hara cost model, net smelter return and financial analysis tools offered by Excel are reported, in order to determine to which variables of the project is more sensitive the NPV.

Passive Samplers Deployment in the Ayapel Swamp for Monitoring Temporal Dynamics of Mercury in the Water Column

Passive sampling is a simple and efficacious sampling technique that guarantees a safe collection and transportation of samples to the analysis site, and obtaining results with more temporal resolution. As a case of study, passive samplers were deployed in the Ayapel Swamp, Colombia, located in the influence zone of open pit gold mines. Mercury, iron and manganese were sampled at two different depths by the Chemcatcher? passive sampler and regular grab sampling. Additionally, dissolved oxygen, oxidation-reduction potential, pH and water temperature were measured. The results showed that depth and time did not have a significant influence (ANOVA, confidence level of 95%) on mercury concentration on both passive samplers and grab sampling. However, concentration of Fe and Hg in passive samplers had a high positive correlation, but it may be because depth increase during sampling period caused the dilution of both analytes. In conclusion, passive samplers proved to be a valuable tool for understanding the response of mercury to the Ayapel Swamp dynamics.

Drillers and mill operators in an open-pit gold mine are at risk for impaired lung function.

BackgroundOccupational studies of associations of exposures with impaired lung function in mining settings are built on exposure assessment and far less often on workplace approach, so the aim of this study was to identify vulnerable occupational groups for early lung function reduction in a cohort of healthy young miners.MethodsData from annual screening lung function tests in gold mining company in Kyrgyzstan were linked to occupations. We compared per cent predicted forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC between occupational groups and tested selected occupations in multivariate regression adjusted for smoking and work duration for the following outcomes: FEV1 < 80 %, FEV1/FVC < 70 % and both.Results1550 tests of permanent workers of 41 occupations (mean age 40.5 ± 9.2 years, 29.8 % never smokers) were included in the analysis. The mean overall VC was 103.0 ± 12.9 %; FVC 109.1 ± 13.0 % and FEV1 100.2 ± 25.9 %. Drillers and smoking food handlers had the lowest FEV1%. In non-smokers, the lowest FEV1 was in drillers (94.9 ± 11.3 % compared to 115.2 ± 17.7 % in engineers). Drillers (adjusted odds ratio (OR) 1.53 (95 % confidence interval (CI) 1.11-2.09)) and mill operators (OR 2.01 (1.13-3.57)) were at greater risk of obstructive ventilation pattern (FEV1/FVC < 70 %).ConclusionsDrilling and mill operations are the highest risk jobs in an open-pit mine for reduced lung function. Occupational medical clinic at site should follow-up workers in these occupations with depth and strongly recommend smoking cessation.

Accelerated glacier shrinkage in the Ak-Shyirak massif, Inner Tien Shan, during 2003–2013

The observed increase in summer temperatures and the related glacier downwasting has led to a noticeable decrease of frozen water resources in Central Asia, with possible future impacts on the economy of all downstream countries in the region. Glaciers in the Ak-Shyirak massif, located in the Inner Tien Shan, are not only affected by climate change, but also impacted by the open pit gold mining of the Kumtor Gold Company. In this study, glacier inventories referring to the years 2003 and 2013 were created for the Ak-Shyirak massif based on satellite imagery. The 193 glaciers had a total area of 351.2±5.6km2 in 2013. Compared to 2003, the total glacier area decreased by 5.9±3.4%. During 2003–2013, the shrinkage rate of Ak-Shyirak glaciers was twice than that in 1977–2003 and similar to shrinkage rates in Tien Shan frontier ranges. We assessed glacier volume in 2013 using volume–area (VA) scaling and GlabTop modelling approaches. Resulting values for the whole massif differ strongly, the VA scaling derived volume is 30.0–26.4km3 whereas the GlabTop derived volume accounts for 18.8–13.2km3. Ice losses obtained from both approaches were compared to geodetically-derived volume change. VA scaling underestimates ice losses between 1943 and 2003 whereas GlabTop reveals a good match for eight glaciers for the period 2003–2012. In comparison to radio-echo soundings from three glaciers, the GlabTop model reveals a systematic underestimation of glacier thickness with a mean deviation of 16%. GlabTop tends to significantly underestimate ice thickness in accumulation areas, but tends to overestimate ice thickness in the lowermost parts of glacier snouts. Direct technogenic impact is responsible for about 7% of area and 5% of mass loss for glaciers in the Ak-Shyirak massif during 2003–2013. Therefore the increase of summer temperature seems to be the main driver of accelerated glacier shrinkage in the area.

Solid–liquid separation method governs the in vitro bioaccessibility of metals in contaminated soil-like test materials

An in vitro gastrointestinal model was used to explore the role of solid–liquid separation method on the bioaccessibility of trace elements in a smelter-impacted soil (NIST-2711) from Helena, MT and a mine overburden from an open-pit gold and silver mine in Mount Nansen, YK (YK-OVB). Separation methods studied included centrifugation (5000g, 12000g), syringe microfiltration (0.45μm), and ultrafiltration (1000kDa, 50kDa, 30kDa, 10kDa, 3kDa). Results indicated that the use of syringe microfiltration generally yields the same bioaccessibility as the use of centrifugation and that the speed of centrifugation does not typically affect metal bioaccessibility. However, ultrafiltration consistently yields a significantly lower bioaccessibility than the use of centrifugation and syringe microfiltration. There are rarely any differences between bioaccessibility estimates generated using a low-resistance (1000kDa) and a high-resistance (3kDa) ultrafiltration membrane; therefore, under the in vitro gastrointestinal conditions modeled herein, negligible quantities of trace elements are complexed to small molecules between 3 and 1000kDa. The primary exceptions to these trends were observed for Pb in NIST-2711 (5000g>12000g>0.45μm>ultrafiltration) and for Tl in NIST-2711 and YK-OVB (5000g∼12000g>0.45μm>ultrafiltration). These results provide valuable information to researchers attempting to expand the use of in vitro bioaccessibility beyond soil Pb and As.

Copper–gold ore processing with ion exchange and SART technology

Anglo Asian Mining has developed a 50,000ozAu/yr open pit gold mine at Gedabek in Western Azerbaijan. The deposit at Gedabek is a copper–gold porphyry, comprising both oxide and sulphide ore mineralisation, which is being mined at the rate of about 1 million tons of ore per year. Ore processing is by conventional cyanide heap leaching, which produces a pregnant leach solution (PLS) containing 1–2ppm of gold, together with 1000ppm or more of copper. The PLS is treated by column ion exchange, using Dow’s gold-selective MINIX resin. Loaded resin is stripped with an acidic thiourea solution, from which gold and silver are electrowon on to stainless steel mesh cathodes. Copper concentrations in the leach solutions are controlled by passing part of the PLS flow through a SART process, where the acronym stands for “Sulphidisation, Acidification, Recycling and Thickening”. The product from the SART process is a copper/silver sulphide precipitate, which is thickened, filtered and dried and then sold for copper smelting.

Environmental geochemistry of the Hycroft Mine: a case study on the limitation of Sobek-style acid-generation predictions

The Hycroft Mine is an open pit gold mine situated along the eastern edge of the Black Rock Desert in NW Nevada, a semi-arid region where annual evaporation significantly exceeds precipitation. The Hycroft deposit is hosted in volcanic breccias and conglomerates of the Tertiary Kamma Mountain volcanic group that have been faulted by north-trending structures that acted as conduits for hydrothermal fluids. An acid-leaching event resulted in the development of vuggy, quartz alunite-altered zones produced by the removal of most minerals, including those capable of buffering acid. Accessory minerals associated with the acid leach zones are rare, except native sulphur which is locally abundant. The complex sulphur mineralogy of the Hycroft deposit, coupled with the deficiency of acid-neutralizing minerals, limits the application of traditional Sobek-style Acid-Base Accounting (ABA) methods that rely upon sulphur speciation data to predict acid-generation potential. A comparison of results from geochemical predictive tests including the modified Sobek ABA method, Net Acid Generation (NAG) test and kinetic humidity cell test (HCT) illustrates the complexity of interpreting ABA data for material containing native sulphur and low solubility sulphate minerals such as alunite. Comparing ABA data to HCT results shows the predictions of acid generation from the ABA test are not consistent with those from the HCT, which is considered a more definitive test for the prediction of acid and metals mobility. The results of this study indicate the ABA test does not provide a reliable prediction of acid generation for samples containing native sulphur and low solubility sulphate minerals. A reasonably good correlation is, however, observed between the HCT and NAG results, suggesting the NAG test is a more effective tool for predicting the geochemical behavior of the Hycroft deposit, and potentially also other deposits with complex sulphur mineralogy. The presence of native sulphur in the acid leach material presents additional challenges with respect to acid-generation prediction due to the unique properties of this mineral. Although acid generation is predicted from the NAG test for samples containing native sulphur, the actual amount of acid and metal release generated by this mechanism in the HCT is limited in comparison to that associated with natural pyrite oxidation, which is the main contributor to acid rock drainage. The potential for acid generation from this mechanism is further limited by the semi-arid site conditions that are unlikely to produce conditions similar to the humidity cell tests that are designed to accelerate the weathering process and enhance mineral-water reaction rates. This study demonstrates the importance of considering the site-specific mineralogical characteristics of the deposit in the selection of the most appropriate geochemical test methods to use in the prediction of potential acid generation.

Mining, development and corporate-community conflicts in Peru

Peru has been the largest gold producer in Latin America since 1996. This is mainly attributable to the open-pit gold mines in the northern regions of Ancash, Cajamarca and La Libertad, which are managed by Barrick Gold Corporation and Newmont Mining Corporation. The expansion of these large-scale mining projects has engendered social protests and conflicts that, in a context of weak institutions, have developed with little oversight from the central government. In some cases, corporate–community conflicts have driven mining corporations towards more responsible management of natural resources. For example, in some remote areas, the mining industry has filled the gap left by the State and has promoted sustainable socio-economic development through public–private partnerships. However, evidence indicates that an enhanced democratic framework with more attentive public management of natural resources is needed before such best practices may be established as the norm rather than the exception. Sustainable mining goes hand-in-hand with good governance.

Testing and modeling the influence of reclamation and control methods for reducing nonpoint mercury emissions associated with industrial open pit gold mines

Industrial gold mining is a significant source of mercury (Hg) emission to the atmosphere. To investigate ways to reduce these emissions, reclamation and dust and mercury control methods used at open pit gold mining operations in Nevada were studied in a laboratory setting. Using this information along with field data, and building off previous work, total annual Hg emissions were estimated for two active gold mines in northern Nevada. Results showed that capping mining waste materials with a low-Hg substrate can reduce Hg emissions from 50 to nearly 100%. The spraying of typical dust control solutions often results in higher Hg emissions, especially as materials dry after application. The concentrated application of a dithiocarbamate Hg control reagent appears to reduce Hg emissions, but further testing mimicking the actual distribution of this chemical within an active leach solution is needed to make a more definitive assessment. Implications: Laboratory and field measurements of mercury flux from materials typically found at large open pit gold mines in Nevada indicate that non-point-source mercury emissions are a significant component of total mercury emissions, but that these nonpoint emissions can be significantly reduced by postmining capping and reclamation, and possibly by chemical treatments of leach ore and tailings waste.

Analysis of the Interaction between Human Operator and Automated Dispatch in Haul Truck Scheduling

This paper presents the findings from a field study of human-automation interaction in an open pit gold mine. Motivated by an earlier study that identified problematic interaction between haul truck operators and dispatch interfaces, focus groups and questionnaires were used to understand what causes the general attitude of suspicion towards the system. Overall trust in the dispatch interface, as well as usability and functionality of the system, were judged as slightly positive. However, the inability of the system to react efficiently to sudden changes on site results in operator frustration. We argue that consequently, the human operator should be utilized as a sensor by the dispatch system. Through operator involvement in the stage of information acquisition, the system’s response to sudden changes can be improved, and discontent reduced.

Distinguishing and characterising point-source mining dust and diffuse-source dust deposits in a semi-arid district of eastern Australia

Abstract The routine monitoring of dust deposition around mines does not typically distinguish between allochthonous and locally-sourced dust. In this paper, contemporary aeolian dust deposition within a semi-arid part of eastern Australia is examined to determine the contribution of an open-pit gold mine to local dust dynamics. Over a 2.5 year period, monthly deposited dust samples were obtained from 12 sites located around the Cowal Gold Mine (CGM), and analysed for inorganic and organic proportions and granulometric properties. Although there was considerable variation in deposition between the gauges and sampling periods, there was a moderate and statistically significant seasonal trend, with mineral dust deposition lowest in winter. Imprinted over this seasonal pattern was a distinct spatial pattern of dust deposition, with gauges downwind of the CGM receiving significantly more dust than those gauges upwind (20 t/km 2 /yr). This effect was most pronounced adjacent to the mine (dust deposition of 60 t/km 2 /yr), where coarse-grained particles comprised a large proportion of the deposited dust, and diminished with distance east of the mine. Such a spatial trend is typical of a point source of dust. Average dust deposition at gauges located 8 km downwind of the mine was only slightly greater than that of gauges upwind of the mine. The ‘background’ dust populations captured at the upwind locations were dominated by fine particles, with modal particle diameters of 3–5 and 13–16 μm common. The macro-organic component of dust deposits also tended to vary seasonally, but the spatial distribution of this material was quite erratic.

O GARIMPO BOM FUTURO COMO FERRAMENTA PARA O ENSINO DE QUÍMICA E DA EDUCAÇÃO AMBIENTAL.

Bom Futuro mining is called the largest open pit gold mining in the world, was discovered in 1987and from this discovery began with the digging of its greatest wealth is cassiterite (SnO2), whichcontains about 66% to 75% tin, and is passed through a beneficiation process, which leaves herwith a tin of 99.98% purity. This ore is used in various purposes such as, tin and alloys as solder,brass, pewter alloy and chemical compounds. The tin helped and continues to help the economyof the state of Rondonia, being increasingly used in our day to day, knowing the potential size ofthe study, this paper aims to propose a visit from mining as a tool in teaching environmentaleducation and chemistry, giving a different look to a gold mining and show the great potential of mining as a major laboratory in the open.

A Field Study of Haul Truck Operations in Open Pit Mines

This paper presents findings from a field study of the operation of haul trucks in two open pit gold mines. Qualitative results relevant to the haul truck operator’s work environment are presented, and the human factors challenges of the work are identified. Three specific issues that stood out from the study are discussed in detail. First, fatigue is identified as a major contributing factor to crashes and overall performance in open pit traffic, heightened by the specific work characteristics of a haul truck operator. Second, negative transfer is discussed as it interferes with the adaptation from one truck type to another: a consequence of inconsistent controls across different truck brands. Third, the under utilization of and the general posture of suspicion towards the dispatch system are reported, with a list of potential reasons related to automation characteristics.

Scaling Non-Point-Source Mercury Emissions from Two Active Industrial Gold Mines: Influential Variables and Annual Emission Estimates

Open-pit gold mines encompass thousands of hectares of disturbed materials that are often naturally enriched in mercury (Hg). The objective of this study was to estimate annual non-point-source Hg emissions from two active gold mines in Nevada. This was achieved by measuring diel and seasonally representative Hg fluxes from mesocosms of materials collected from each mine. These measurements provided a framework for scaling emissions over space and time at each mine by identifying the important variables correlated with Hg flux. The validity of these correlations was tested by comparisons with measurements conducted in situ at the mines. Of the average diel fluxes obtained in situ (92 daily flux measurements), 81% were within the 95% prediction limits of the regressions developed from the laboratory-derived data. Some surfaces at the mines could not be simulated in the laboratory setting (e.g., material actively leached by cyanide solution and tailings saturated with cyanide solution), and as such in situ data were applied for scaling. Based on the surface areas of the materials and environmental conditions at the mines during the year of study, non-point-source Hg releases were estimated to be 19 and 109 kg·year(-1). These account for 56% and 14%, respectively, of the overall emissions from each mine (point + nonpoint sources). Material being heap-leached and active tailings impoundments were the major contributors to the releases (>60% combined) suggesting that as mining operations cease, releases will decline.

Measurement of surface mercury fluxes at active industrial gold mines in Nevada (USA)

Mercury (Hg) may be naturally associated with the rock units hosting precious and base metal deposits. Active gold mines are known to have point source releases of Hg associated with ore processing facilities. The nonpoint source release of Hg to the air from the large area (hundreds to thousands of hectares) of disturbed and processed material at industrial open pit gold mines has not been quantified. This paper describes the field data collected as part of a project focused on estimating nonpoint source emissions of Hg from two active mines in Nevada, USA. In situ Hg flux data were collected on diel and seasonal time steps using a dynamic flux chamber from representative mine surfaces. Hg fluxes ranged from < 1500 ng m −2 day −1 for waste rock piles (0.6–3.5 μg g −1) to 684,000 ng m −2 day −1 for tailings (2.8–58 μg g −1). Releases were positively correlated with material Hg concentrations, surface grain size, and moisture content. Highest Hg releases occurred from materials under active cyanide leaching and from tailings impoundments containing processed high-grade ore. Data collected indicate that as mine sites are reclaimed and material disturbance ceases, emissions will decline. Additionally local cycling of atmospheric Hg (deposition and re-emission) was found to occur.

English

An open-pit gold mine in the Mother-Lode mining region of the Sierras was essentially closed according to an accepted mine closure plan. However, because one element of the plan was not completed, due to technical disagreements, the entire mine site is now being re-examined, conceptually resulting, in revisions to the closure plans for the entire site. Elements of the mine include open-pits, a pit lake, waste rock piles, tailings pile, and a site wide surface water drainage system. Concerns to be re-addressed include: off site migration of dissolved metals in groundwater, stormwater sediment transport, revised criteria for side slope gradients of waste rock piles, disposition of pit lakes, and other complex issues.

Reclaiming A Gold Mine

An open-pit gold mine in the Mother-Lode mining region of the Sierras was essentially closed according to an accepted mine closure plan. However, because one element of the plan was not completed, due to technical disagreements, the entire mine site is now being re-examined, conceptually resulting, in revisions to the closure plans for the entire site. Elements of the mine include open-pits, a pit lake, waste rock piles, tailings pile, and a site wide surface water drainage system. Concerns to be re-addressed include: off site migration of dissolved metals in groundwater, stormwater sediment transport, revised criteria for side slope gradients of waste rock piles, disposition of pit lakes, and other complex issues.

Development of the Sleeper Pit Lake

The Sleeper open pit gold mine operated from the mid-1980s through the mid-1990s. Operations were mostly sub-water table and extensive dewatering was required to lower groundwater levels by 180 m. Dewatering flows peaked at 930 L/s, with most flow contributed from an alluvial aquifer. After completion of mining, the pit was rapidly filled with water pumped from the alluvial aquifer to reduce the exposure time of sulfide wall rocks and waste rocks in the ultimate pit. The pumped alluvial groundwater provided a large volume of low total dissolved solids (TDS), high alkalinity water that controlled the early chemistry. The rising lake waters were amended with lime to buffer excess acidity contributed to the lake from reactive pit wall rocks during submergence. The pore water contained in submerged waste rock at the base of the pit was elevated in TDS and subsequently of higher density that the lake water. The density contrast and waste rock location limited contributions of waste rock pore water to the main body of the lake. Some stratification of the early lake occurred, with shallow water characterized by higher pH, low dissolved metals, and sulfate; deeper water had lower pH and higher dissolved metals and sulfate. The reservoir of alkalinity in the shallow layer mixed with the deeper waters and created a stabilized lake with a homogenized column that exceeded water quality expectations. Current water quality meets all Nevada primary drinking water standards with the exception of sulfate, TDS, and manganese, which are slightly elevated, as predicted. Chemistry has remained stable since development of the initial lake.

Modeling the dewatering and depressurization of the Lihir open-pit gold mine, Papua New Guinea

The open pit at the Lihir Gold Mine, Papua New Guinea, is planned ultimately to reach more than 200 m below sea level. Cooling and depressurization of the geothermal resource associated with the gold mineralisation is an essential part of the mining operation. This paper deals with the development of a numerical model of the resource capable of representing reservoir processes associated with shallow dewatering, geothermal development and providing sufficient detail for pit-wall stability calculations. Use was made of iTOUGH2 [Finsterle, 1999. iTOUGH2 User’s Guide, Report LBNL-40040] running on a cluster of LINUX workstations to aid the fitting of some model parameters. Use of this program in a parallel computational environment was essential to complete the parameter fitting in an acceptable time. A detailed model containing almost 90,000 elements has been developed as an aid to pit-wall stability calculations and this has been run on a Cray and a LINUX cluster using a multiprocessor version of TOUGH2 recently developed at LBNL [ Zhang et al., 2001. Parallel computing technique for large-scale reservoir simulation of multi-component and multiple fluid flow].