scholarly journals Impact Assessment of Atmospheric Pollutants Emissions from Mining Operations at Ghana Managanese Company Ltd.

2016 ◽  
Vol 16 (2) ◽  
pp. 65-72
Author(s):  
N. Amegbey ◽  
B. O. Afum ◽  
S. Ndur ◽  
E. Coffie-Anum
Keyword(s):  
Near Field ◽  
Atmospheric Pollutants ◽  
Mitigation Measures ◽  
Mining Operations ◽  
Regulatory Requirement ◽  
Airborne Particulates ◽  
Regulatory Limits ◽  
Crushing Plant ◽  
Particulates Matter ◽  
Matter Concentration

Atmospheric pollutants diffusion study was conducted around the operational sites and immediate neighbouring communities of Ghana Manganese Company (GMC). The pollutants are emitted by sources associated with the main operations and activities of the mine including on-bench rock drilling and blasting, material excavation and hauling, vehicular movements and mine machinery exhaust emissions, as well as crushing of blasted rocks. Methodologies involving computerised dispersion modelling was used to estimate near-field ambient pollutant impacts on neighbouring Tarkwa-Banso community, at 400 m from the Mine’s nearest operational site (Pit C North). The community is located in the dispersive fan of North to the East-South-Eastern part of the mine site. Measured airborne particulates (PM10 and TSP) concentrations in the Tarkwa-Banso community were below Ghana EPA’s permissible limits of 70 µg/m3 and 150 µg/m3 respectively. The predicted monthly concentrations of the airborne particulates (PM10 and TSP) at 400 m buffer from the crushing plant were greatly lower than the permissible regulatory limits. With effective dust mitigation measures, the predicted PM10 and TSP dust concentrations emanating from drilling, blasting, loading and hauling activities at Pit C North were also generally lower than the regulatory requirement. All the predicted monthly concentrations of NOx and SO2 at the 400 m buffer from Pit C North were significantly lower than the allowable regulatory requirement of 60 µg/m3 and 100 µg/m3 respectively. The study indicates that, the operation of the crushing plant together with the general mining operations at Pit C North in the mine has no significant impact on Tarkwa-Banso community.  Keywords: Impacts, Particulates Matter, Concentration Levels, Environment, Prediction

Analysis of Structural and Non-Structural Problems by Coupling of Finite and Infinite Elements

2014 ◽  
Vol 578-579 ◽  
pp. 445-455
Author(s):  
Mustapha Demidem ◽  
Remdane Boutemeur ◽  
Abderrahim Bali ◽  
El-Hadi Benyoussef
Keyword(s):  
Numerical Technique ◽  
Near Field ◽  
Main Idea ◽  
Far Field ◽  
Mining Operations ◽  
Infinite Element ◽  
Infinite Elements ◽  
Structural Problems ◽  
Infinite Element Method ◽  
Element Method

The main idea of this paper is to present a smart numerical technique to solve structural and non-structural problems in which the domain of interest extends to large distance in one or more directions. The concerned typical problems may be the underground excavation (tunneling or mining operations) and some heat transfer problems (energy flow rate for construction panels). The proposed numerical technique is based on the coupling between the finite element method (M.E.F.) and the infinite element method (I.E.M.) in an attractive manner taking into consideration the advantages that both methods offer with respect to the near field and the far field (good accuracy and sensible reduction of equations to be solved). In this work, it should be noticed that the using of this numerical coupling technique, based on the infinite element ascent formulation, has introduced a more realistic and economic way to solve unbounded problems for which modeling and efficiency have been elegantly improved. The types of the iso-parametric finite elements used are respectively the eight-nodes (Q8) and the four-nodes (Q4) for the near field. However, for the far field the iso-parametric infinite elements used are the eight-nodes (Q8I) and the six-nodes (Q6I).

Blue mussels (Mytilus edulis) as bioindicators of stable water quality in Sydney Harbour during remediation of the Sydney Tar Ponds, Nova Scotia, Canada

2013 ◽  
Vol 48 (4) ◽  
pp. 358-371 ◽  
Author(s):  
Tony R. Walker ◽  
Devin Macaskill ◽  
Peter Weaver
Keyword(s):  
Mytilus Edulis ◽  
Near Field ◽  
Temporal Distribution ◽  
Mitigation Measures ◽  
Blue Mussels ◽  
Sydney Harbour ◽  
Polycyclic Aromatic ◽  
Individual Pahs ◽  
Spatio Temporal ◽  
Environmental Mitigation

Contaminants were measured in blue mussels (Mytilus edulis) in Sydney Harbour (SH) during remediation of the Sydney Tar Ponds (STPs) to assess the spatio-temporal distribution of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and metals during baseline and remediation. Overall distribution of chemicals in mussels was compared to contaminants in other marine indicators. Metal concentrations in mussels showed some minor temporal variability, but did not appear to be directly related to remediation activities. Contaminants showed stable or decreasing concentrations, except Pb and Zn. Individual PAH compounds were mostly undetected, except for fluoranthene and pyrene. Concentrations of fluoranthene in mussels and water were weakly related (R2 = 0.72). PCBs were undetected, except during year 2 remediation at some near-field stations. Contaminants measured during this study were much lower than previously reported in other studies of mussels in SH, likely due to ongoing natural recovery and because of environmental mitigation measures implemented during remediation activities at the STPs. The lack of detection of most individual PAHs, PCBs, and low bioaccumulation of metals during baseline and remediation using mussels as bioindicators reveal subtle improvements in environmental quality in SH.

scholarly journals Case-based reasoning system for prediction of fuel consumption by haulage trucks in open-pit mines

2021 ◽  
Vol 11 (4) ◽  
pp. 3129
Author(s):  
Gomolemo Tadubana ◽  
Boyce Sigweni ◽  
Raymond Suglo
Keyword(s):  
Fuel Consumption ◽  
Fuel Efficiency ◽  
Open Pit ◽  
Mitigation Measures ◽  
Open Pit Mining ◽  
Case Based Reasoning ◽  
Mining Operations ◽  
Open Pit Mines ◽  
Absolute Residual ◽  
Case Based

The shovel-truck system is commonly used in open-pit mining operations. Truck haulage cost constitutes about 26% of open-pit mining costs as the trucks are mostly powered by diesel whose cost is escalating annually. Therefore, reducing fuel consumption could lead to a significant decrease in overall mining costs. Various methods have been proposed to improve fuel efficiency in open-pit mines. Case-based reasoning (CBR) can be used to estimate fuel consumption by haulage trucks. In this work, CBR methods namely case-based reasoning using forward sequential selection (CBR-FSS), traditional CBR, and Naïve techniques were used to predict fuel consumption by trucks operating at Orapa Mine. The results show that the CBR method can be used to predict fuel consumption by trucks in open-pit mines; the predicted values of fuel consumption using the CBR-FSS technique gave much lower absolute residual values, higher standardised accuracy values, and effect sizes than those of other prediction techniques on all the datasets used. The system will enable mine planners to know the fuel consumed per trip and allow them to take mitigation measures on trucks with high fuel consumption.

Detailed Chemical Modelling Predictions of Emissions From a Reheated Gas Turbine Engine With Application to Future Supersonic Aircraft

1997 ◽  
Author(s):  
T. J. Foster ◽  
C. W. Wilson
Keyword(s):  
Nitrogen Dioxide ◽  
Gas Turbine ◽  
Near Field ◽  
Gas Turbine Engine ◽  
Atmospheric Pollutants ◽  
Gaseous Emissions ◽  
Oxides Of Nitrogen ◽  
Turbine Engine ◽  
Supersonic Aircraft ◽  
Chemical Modelling

The exhaust plumes of modern gas turbine engines are of great concern due to the emission of atmospheric pollutants, such as carbon monoxide, unburnt hydrocarbons and oxides of nitrogen (NOx) and visibility caused by the presence of black carbonaceous smoke and nitrogen dioxide (NO2) giving rise to a new plume visibility phenomena of “yellow smoke”. A detailed hydrocarbon oxidation and NOx scheme was used to simulate chemical reactions occurring through the gas turbine engine and near-field plume. In addition limited experimental measurements have been made directly behind a reheated gas turbine engine to measure gaseous emissions and to quantify the rate of conversion of nitric oxide to nitrogen dioxide. Two experimental methods were employed to measure emissions; the first a conventional probe technique, the second a non-intrusive method. Results show a fair agreement between experimental data and predicted emissions, showing the maximum conversion of NO to NO2 at low reheat fuel flowrates. These detailed results can be used as an input to atmospheric modelling codes.

Severe Accident Related Vulnerabilities, Potential Design Enhancements and Opportunities for International Cooperation in Risk Reduction in Pressurized Heavy Water Reactors

2015 ◽  
Author(s):  
Sunil Nijhawan
Keyword(s):  
Single Unit ◽  
Severe Accident ◽  
Mitigation Measures ◽  
Mechanical Degradation ◽  
Optimum Number ◽  
Source Terms ◽  
Regulatory Requirement ◽  
Severe Accidents ◽  
Design Basis ◽  
Water Reactors

Operating CANDU PHWRs present significant challenges with respect to their ability to mitigate accidents that are beyond the envelope of design basis drafted over 40 years ago. Today, consideration of severe accidents is a public as well as a regulatory requirement whose implementation begs serious reconsideration in an international coordinated effort. The PHWR enhanced vulnerabilities to accidents such as a sustained loss of AC power, as in Fukushima, arise not only out of the inherent design features but also out of the institutional arrangements that surround their licensing. For one, the reactors will, in absence of a containing pressure vessel as in PWRs, put fission product activity directly into the containment, sport multiple potential containment bypass vulnerabilities and produce copious amounts of flammable gases due to presence of large amounts of Zircaloy in fuel channels and carbon steel in feeders. The relatively thin walled, stepped, welded Calandria vessel into which the disassembled core debris will rest has potential to mechanically fail early, causing explosive and energetic interactions of hot debris with enveloping water. This can catastrophically fail the reactor structures. For severe accidents the containments, well designed for design basis accidents, are either small and weak as in single unit plants or unable to practically take any significant over pressure in negative pressure multi-unit reactor buildings that depend upon a single vacuum building, too small for a multi-unit severe accident. The paper presents analytical arguments in support of these observations, lists conclusions from a series of design reviews and discusses development of ROSHNI, a new generation PHWR dedicated computer code package for simulating an unmitigated station blackout scenario. It does not directly address the institutional issues that handicap a potent reduction of the residual risk posed by continued operation of these reactors without serious design upgrades but discusses the regulatory failures in this regard. It introduces ROSHNI, a newly developed severe accident simulation package that models the reactor core in a greatly enhanced detail necessitated by the variability amongst reactor fuel channels. For a single unit CANDU 6 reactor, the code simulates thermal-mechanical degradation of 4,560 fuel bundles in 380 diverse fuel channels individually (for a total of over 70,000 dissimilar fuel entities) and computes source terms into containment of flammable deuterium gas and fission products. A number of questions are raised about differences between Hydrogen source terms and mitigation measures that are being implemented for light water reactors and Deuterium specific reaction kinetics in generation and mitigation that must be clearly differentiated but ignored so far by PHWR operators. A discussion of effectiveness of certain severe accident specific design upgrade measures that have been implemented at some operating plants is also addressed. For example, potential for a smaller than optimum number (for severe accidents) of PARS units to actually cause Deuterium/Hydrogen explosions as an unintended consequence is discussed. Continued reluctance of CANDU utilities to address a long standing issue of inadequacy of reactor overpressure protection is also detailed.

scholarly journals Evaluating Productivity Management of Materials Handling System at Mempeasem Gold Mine

2020 ◽  
Vol 5 (8) ◽  
pp. 948-954
Author(s):  
Desmond B. Munyadzwe ◽  
Nonduduzo B. Mamba ◽  
Raymond Sogna Suglo
Keyword(s):  
Productivity Loss ◽  
Open Pit ◽  
Mitigation Measures ◽  
Base Case ◽  
Ranking Methods ◽  
Mining Operations ◽  
Materials Handling ◽  
Ranking Model ◽  
Productivity Management ◽  
Correlation Parameters

Productivity management in materials handling is critical to mining operations. Most open pit mines use modular dispatch systems to control and monitor the movement of their materials handling equipment and operations. Statistical methods can be used on the data collected by the dispatch systems to identify major losses in time, tonnage and finances in productivity management. In this study, three ranking methods (a base case and two modified ranking methods) were used to evaluate the significance of the deviation and correlation parameters in productivity losses. A load and haul productivity loss ranking model was developed using data obtained from Mempeasem Gold Mine’s from January to October 2018 and tested with data obtained in November 2018. The results show that the ranking model can be used in the analysis of production data over any period of time and that the model is applicable in the analysis of the performance of all types of discrete load and haul equipment (trucks and excavators), either operating individually or in combination. The ranking based on deviation values is useful for comparative purposes. However, the ranking based on reduced values is more useful in decision making processes as it enables mine operators to take mitigation measures according to the level of priority of each item. Decision makers could also use the suggested colour coding for easy identification of the priority losses.

Freeze-dried dispersions for automated SEM analysis of individual submicron airborne particulates

1992 ◽  
Vol 50 (1) ◽  
pp. 408-409
Author(s):  
Karen A. Katrinak ◽  
David W. Brekke ◽  
John P. Hurley
Keyword(s):  
Air Pollutants ◽  
Size Range ◽  
Sem Analysis ◽  
Individual Particle ◽  
Chemical Data ◽  
Particle Analysis ◽  
Bulk Analysis ◽  
Airborne Particulates ◽  
Freeze Dried ◽  
Individual Particle Analysis

Individual-particle analysis is well established as an alternative to bulk analysis of airborne particulates. It yields size and chemical data on a particle-by-particle basis, information that is critical in predicting the behavior of air pollutants. Individual-particle analysis is especially important for particles with diameter < 1 μm, because particles in this size range have a disproportionately large effect on atmospheric visibility and health.

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