M. Ataei; E. Tajvidi Asr; R. Khalokakaie; K. Ghanbari; M. R. Tavakoli Mohammadi
Abstract
Environmental impact assessment (EIA) has led to the dominance of planners on the natural environment of the regions, providing the possibility of continuously monitoring and controlling the status quo by management staff. In this regard, a new semi-quantitative model is presented for the EIA of the ...
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Environmental impact assessment (EIA) has led to the dominance of planners on the natural environment of the regions, providing the possibility of continuously monitoring and controlling the status quo by management staff. In this regard, a new semi-quantitative model is presented for the EIA of the Eastern Alborz Coal Mining complex using the matrix method, and determining the corresponding impacting factors and environmental components. For this purpose, the expert opinions are used to gather the preliminary data and score the parameters involved. The effect of each impacting factor involved on each environmental component is determined by quantifying the qualitative comments. According to the results obtained, the components air quality, human health and safety, and ecology and soil of the area undergo the most environmental damages from the mining activities. Then the EIA results obtained are used to assess the sustainability of the complex using the Phillips mathematical model. The results obtained indicate that the sustainability of this complex is weak, and, therefore, the preventive environmental measures with a preference must be recommended to reduce the environmental damages to its components.
M. R. Tavakoli Mohammadi; Seyed M. J. Koleini; M. Abdollahy
Abstract
Efforts to increase the mass transfer coefficient, enhance the contact area, and decrease the power input of contractors have given risen to the development of the pre-dispersed solvent extraction (PDSE) contactor and the devise of the new dissolved nitrogen PDSE (DNPDSE) contactors. The studies conducted ...
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Efforts to increase the mass transfer coefficient, enhance the contact area, and decrease the power input of contractors have given risen to the development of the pre-dispersed solvent extraction (PDSE) contactor and the devise of the new dissolved nitrogen PDSE (DNPDSE) contactors. The studies conducted after the design of the new contactor to determine the working conditions for its suitable performance (2.5-3.5 bar pressure, 0.1 L/min sparger flow rate, and 1.5 L of the aqueous phase) showed that for all the evaluated conditions (i.e. the pressure, polyaphron type, and dilution percentage), the recovery in the DNPDSE contactor was higher than that in the PDSE one. In addition, pictures of the performance modes of the two contactor indicated the presence of the organic phase in the form of colloidal gas aphrons (CGAs) in the DNPDSE contactor and of polyaphron aggregations in the PDSE one. This is a good reason for the increased copper recovery in the DNPDSE contactor. The best recovery for the extraction process in the DNPDSE contactor was achieved using the anionic polyaphron of sodium dodecylbenzene sulphonate (NaDBS) with five-fold dilution at 3.5 bar.
Mohammad Reza Samadzadeh Yazdi; Mohammad Reza Tavakoli Mohammadi; Ahmad Khodadadi
Abstract
Arsenic is one of the heavy metals and nearly all its compounds, especially organic compounds, are toxic. The wide spectrum of diseases caused by this element has led to evaluation of the toxicity of different arsenic species and identification of the major natural and anthropogenic pollution sources ...
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Arsenic is one of the heavy metals and nearly all its compounds, especially organic compounds, are toxic. The wide spectrum of diseases caused by this element has led to evaluation of the toxicity of different arsenic species and identification of the major natural and anthropogenic pollution sources of it in the nature. Mining activities are among the main sources of anthropogenic pollution of soil and water by arsenic. The purpose of this study was geochemical modeling of different arsenic species in the wastewater of the tailings dam of Mouteh Gold processing plant in Iran to evaluate the effect of pH and temperature on the stability of these components. Modeling was done using MINTEQ software. The results showed that arsenic species at different pH values under study were H3AsO3, H2AsO3- and HAsO32-, and their actual concentration in the plant wastewater were negligible. MINTEQ software introduced H3AsO4, H2AsO4-, HAsO42- and AsO43- as arsenic V species at different pH values, of which HAsO42- and AsO43- were the main components of arsenic in plant wastewater. Given the low toxicity of arsenic V species and their easier elimination relative to arsenic III species, in the current conditions, the plant wastewater is in a good status in terms of arsenic pollution. Also temperature changes have little effect on the concentration of various arsenic species in the wastewater.
