A new practical approach to risk management for underground mining project in Quebec

The mining industry worldwide is currently experiencing an economic boom that is contributing to economic recovery and social progress in many countries. For this to continue, the mining industry must meet several challenges associated with the start-up of new projects. In a highly complex and uncertain environment, rigorous management of risks remains indispensable in order to repel threats to the success of mining.In this article, a new practical approach to risk management in mining projects is presented. This approach is based on a novel concept called “hazard concentration” and on the multi-criteria analysis method known as the Analytic Hierarchy Process (AHP). The aim of the study is to extend the use of this approach to goldmines throughout Quebec. The work is part of a larger research project of which the aim is to propose a method suitable for managing practically all risks inherent in mining projects.This study shows the importance of taking occupational health and safety (OHS) into account in all operational activities of the mine. All project risks identified by the team can be evaluated. An adaptable database cataloguing about 250 potential hazards in an underground goldmine was constructed. In spite of limitations, the results obtained in this study are potentially applicable throughout the Quebec mining sector.     

Effect of using limestone fines on the chemical shrinkage of pastes and mortars

Environmental Science and Pollution Research - The main aim of this study is to examine the effect of incorporating limestone fine (LF) on chemical shrinkage of pastes and mortars. For this...     

Characterization of exhaust particles from military vehicles fueled with diesel,gasoline, and JP-8

Diluted exhaust from selected military aircraft ground-support equipment (AGE) was analyzed for particulate mass, elemental carbon (EC) and organic carbon (OC), SO4(2-), and size distributions. The experiments occurred at idle and load conditions and utilized a chassis dynamometer. The selected AGE vehicles operated on gasoline, diesel, and JP-8. These military vehicles exhibited concentrations, size distributions, and emission factors in the same range as those reported for nonmilitary vehicles. The diesel and JP-8 emission rates for PM ranged from 0.092 to 1.1 g/kg fuel. The EC contributed less and the OC contributed more to the particulate mass than reported in recent studies of vehicle emissions. Overall, the particle size distribution varied significantly with engine condition, with the number of accumulation mode particles and the count median diameter (CMD) increasing as engine load increased. The SO4(2-) analyses showed that the distribution of SO4(2-) mass mirrored the distribution of particle mass.     

Report: Combustion Byproducts and Their Health Effects: Summary of the 10th International Congress

The 10th International Congress on Combustion Byproducts and their Health Effects was held in Ischia, Italy, from June 17-20, 2007. It is sponsored by the US NIEHS, NSF, Coalition for Responsible Waste Incineration (CRWI), and Electric Power Research Institute (EPRI). The congress focused on: the origin, characterization, and health impacts of combustion-generated fine and ultrafine particles; emissions of mercury and dioxins, and the development/application of novel analytical/diagnostic tools. The consensus of the discussion was that particle-associated organics, metals, and persistent free radicals (PFRs) produced by combustion sources are the likely source of the observed health impacts of airborne PM rather than simple physical irritation of the particles. Ultrafine particle-induced oxidative stress is a likely progenitor of the observed health impacts, but important biological and chemical details and possible catalytic cycles remain unresolved. Other key conclusions were: (1) In urban settings, 70% of airborne fine particles are a result of combustion emissions and 50% are due to primary emissions from combustion sources, (2) In addition to soot, combustion produces one, possibly two, classes of nanoparticles with mean diameters of?~10?nm and?~1?nm. (3) The most common metrics used to describe particle toxicity, viz. surface area, sulfate concentration, total carbon, and organic carbon, cannot fully explain observed health impacts, (4) Metals contained in combustion-generated ultrafine and fine particles mediate formation of toxic air pollutants such as PCDD/F and PFRs. (5) The combination of metal-containing nanoparticles, organic carbon compounds, and PFRs can lead to a cycle generating oxidative stress in exposed organisms.     

Natural radioactivity and dose assessment for phosphate rocks from Wadi El-Mashash and El-Mahamid Mines, Egypt

The activity concentrations of (226)Ra, (232)Th and (40)K have been measured by gamma spectroscopy (sodium iodide NaI(Tl) detector) in phosphate rock samples, collected from the Wadi El-Mashash, a site located in the central eastern desert, and El-Mahamid in the Nile valley, Egypt. The average activity concentrations of (226)Ra, (232)Th and (40)K (Bq kg(-1)) in phosphate rocks were 665.8+/-33.4, 329.4+/-17 and 587.6+/-29.4 for Wadi El-Mashash and 566.8+/-28.6, 217.3+/-11.8 and 560.1+/-28 for El-Mahamid, respectively. The corresponding values for shale rocks were 85.2+/-5.7, 93.3+/-5.6 and 303.1+/-15.2 Bq kg(-1), respectively. As a measure of radiation hazard to the occupational workers and public, the Ra equivalent activities, representative level index and dose rates due to natural radionuclides at 1 m above the ground surface were estimated. The calculated external gamma-radiation dose received by the workers of the phosphate mine are 538 and 418 microSv/y, which is far below the permitted dose of 20 mSv/y recommended by the International Commission of Radiation Protection [ICRP-60, 1990. Radiation Protection: 1990 Recommendation of the International Commission on Radiological Protection, Oxford, Pergamon Preis.] for workers.     

Engineered biochar composites with zeolite,silica, and nano-zerovalent iron for the efficient scavenging of chlortetracycline from aqueous solutions

Date palm waste–derived biochar (DBC) was produced through pyrolysis (600 °C) and modified with zeolite (Z-DBC), silica (S-DBC), or nano-zerovalent iron (nZVI-DBC) to design efficient sorbents. The pristine and engineered biochars were characterized by SEM, XRD, BET, TGA, CHNS-O, and FTIR to investigate the surface, structural, and mineralogical composition. The nZVI-DBC exhibited lowest pH (6.15) and highest surface area (220.92 m² g⁻¹), carbon (80.55%), nitrogen (3.78%), and hydrogen (11.09%) contents compared with other biochars. Isotherm sorption data for chlortetracycline (CTC) removal from aqueous solutions was described well by Langmuir and Redlich–Peterson isotherms showing the highest fitness (R² values in the range of 0.88–0.98 and 0.88–0.99, respectively). Langmuir predicted maximum CTC adsorption capacity was in order of nZVI-DBC (89.05 mg g⁻¹) > S-DBC (45.57 mg g⁻¹) > Z-DBC (30.42 mg g⁻¹) > DBC (28.19 mg g⁻¹). Kinetics adsorption data was best described by power function model (R² = 0.93–0.99), followed by interaparticle diffusion (R² = 0.85–0.96) model. The nZVI-DBC performed outclass by removing 98% of CTC, followed by S-DBC (68%), Z-DBC (35%), and DBC (36%). Chemisorption, H-bonding, and interaparticle diffusion were the operating mechanisms for CTC adsorption onto DBC, S-DBC, and Z-DBC, while π-π electron donor–accepter interactions and redox reactions augmented these mechanisms for highest CTC adsorption onto nZVI-DBC. Therefore, nZVI-DBC may serve as an efficient green technology for the removal of CTC from aqueous solutions and to reduce surface date palm waste pollution.

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Assessment of the effect of welding fumes on welders’ cognitive failure and health-related quality of life

Introduction. This study examined whether cognitive symptoms and health-related quality of life can be affected by welding fume exposure. Method. Participants consisted of welders (n?=?40) and welder assistants (n?=?25) from welding units as the exposed group, and office workers (n?=?44) as the non-exposed group. All participants were studied using ambient air monitoring and two types of questionnaires: the Cognitive Failures Questionnaire (CFQ) and the 36-item Short Form Health Survey (SF-36). Results. Welders and welder assistants were exposed to higher concentrations of all airborne metals than office employees, except for aluminum and chromium (p?p?M (SD)?=?54.84 (17.88)). The relationships between total CFQ score and the measured concentration of nickel at peak work rate was significant for welders. Conclusion. Cognitive symptoms and health-related quality of life were not related to the measures of welding fume exposure and further research should be performed to find other influencing factors.     

Protective effects of Persea americana fruit and seed extracts against chemically induced liver cancer in rats by enhancing their antioxidant,anti-inflammatory,and apoptotic activities

Environmental Science and Pollution Research - This study aims to explore the chemopreventive mechanisms of hydroethanolic extracts from avocado (Persea Americana) in diethylnitrosamine...     

Atrazine distribution measured in soil and leachate following infiltration conditions

Atrazine transport through packed 10 cm soil columns representative of the 0-10 cm soil horizon was observed by measuring the atrazine recovery in the total leachate volume, and upper and lower soil layers following infiltration of 7.5 cm water using a mechanical vacuum extractor (MVE). Measured recoveries were analyzed to understand the influence of infiltration rate and delay time on atrazine transport and distribution in the column. Four time periods (0.28, 0.8, 1.8, and 5.5 h) representing very high to moderate infiltration rates (26.8, 9.4, 4.2, and 1.4 cm/h) were used. Replicate soil columns were tested immediately and following a 2-d delay after atrazine application. Results indicate atrazine recovery in leachate was independent of infiltration rate, but significantly lower for infiltration following a 2-d delay. Atrazine distribution in the 0-1 and 9-10 cm soil layers was affected by both infiltration rate and delay. These results are in contrast with previous field and laboratory studies that suggest that atrazine recovery in the leachate increases with increasing infiltration rate. It appears that the difference in atrazine recovery measured using the MVE and other leaching experiments using intact soil cores from this field site and the rain simulation equipment probably illustrates the effect of infiltrating water interacting with the atrazine present on the soil surface. This work suggests that atrazine mobilization from the soil surface is also dependent on interactions of the infiltrating water with the soil surface, in addition to the rate of infiltration through the surface soil.