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Technological and Environmental Behavior of Coal Fly Ash in Lime-Based Materials

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Geomaterials 2022年第2期12卷 15-29页

作者： Mamoudou Sall gora dieye Alassane Traoré Prince Momar Gueye Saliou Diouf Abdou Ciss Wade Djibril Diop Laboratory of X-Ray Department of Physics Faculty of Sciences and Techniques Cheikh Anta Diop University Dakar Senegal Institute of Applied Nuclear Technology Department of Physics Faculty of Sciences and Techniques Cheikh Anta Diop University Dakar Senegal Laboratory of Civil Engineering Materials High Polytechnic School Cheikh Anta Diop University Dakar Senegal

Coal fly ash is considered an industrial by-product derived from coal combustion in thermal power plant. It is one of the most complex anthropogenic materials. Its improper disposal has become an environmental concern and resulted in a waste of recoverable resources. The aim of this paper is to study the physico-chemical characteristics of binders based on coal fly ash and lime in order to develop an eco-cement. The various characterization tests carried out are X-ray fluorescence, X-ray diffraction, compressive strengths, thermophysical properties and setting time. X-ray fluorescence and X-ray diffraction were used to determine the chemical composition and phases of fly ash, lime and binders. This allowed us to see that the chemical composition of fly ash is similar to that of cement. Compressive strengths of mortars containing 20%, 40%, 60% and 80% of fly ash have shown that fly ash has a long-term positive effect which might be related to a pozzolanic activity. The L3 binder consisting of 60% of coal fly ash and 40% lime has a higher compressive strength than the others. The binder setting start time is greater than that of cement but shorter than that of lime. The study of the thermophysical properties of the L3 binder shows that it has a higher thermal resistance than cement mortar. Moreover, it heats up less quickly because of its low effusivity compared to that of the latter. This analysis highlighted the principal characteristics that must be taken into account to use coal fly correctly in lime-based materials.

关键词： Coal Fly Ash Lime Binder X-Ray Fluorescence X-Ray Diffraction Thermomechanical Behavior

Comparative Characteristics of Hydrated Lime with Fine Sewage Sludge Ash (FSSA) and Coal Fly Ash (CFA)

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Journal of Minerals and Materials Characterization and Engineering 2022年第5期10卷 446-459页

作者： Mamoudou Sall Abdou Ciss Wade gora dieye Alassane Traoré Prince Momar Gueye Prince Momar Gueye Saliou Diouf Déthié Thiaw Khalifa Ababacar Diop Djibril Diop Laboratory of X-Ray Department of Physic Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal Institute of Applied Nuclear Technology Department of Physics Faculty of Sciences and Techniques University of Cheikh Anta Diop Dakar Senegal Laboratory of Civil Engineering Materials High Polytechnic School University of Cheikh Anta Diop Dakar Senegal

The disposal of waste has become an environmental issue due to the limited available landfilling space. This paper aims to compare the characteristics of hydrated lime with fine sewage sludge ash (FSSA) and coal fly ash (CFA). Multiple techniques, X-ray fluorescence (XRF), X-ray diffraction (XRD), the Fourier transform infrared (FTIR), compressive strengths, thermophysical properties, and setting time were used to assess the physicochemical characteristics of the lime-based materials. X-ray fluorescence and X-ray diffraction were used to determine the chemical composition and phases of ashes, lime and binders. The results showed that the chemical composition of ashes is similar to that of cement. Besides glass, the main minerals identified in CFA and FSSA are quartz (SiO2) and anhydrite (CaSO4). Moreover, calcium aluminium oxide (Ca3Al2O6) was detected for CFA and phosphorus calcium silicate (Ca2SiO4-Ca3(PO4)2) for FSSA and minor phases were detected for both. FTIR measurements were carried out to characterize the inorganics components of different samples. Compressive strengths of mortars with different formulations have shown that both have a long-term positive effect which might be related to a pozzolanic activity. For the CFA the L3 binder consisting of 60% of coal fly ash and 40% lime has a higher compressive strength than the others while for the FSSA the L4 binder consisting of 80% fine ash and 20% lime has a higher compressive strength than the others. Both binders setting start times are greater than that of cement but shorter than that of lime. The study of the thermophysical properties of binders shows that they have a higher thermal resistance than cement mortar. Moreover, binders heat up less quickly because of their low effusivity compared to cement. Lime-based materials system could be a promising option to both relieve t

关键词： Coal Fly Ash Fine Sewage Sludge Ash Lime Binder Microstructure Thermomechanical Behavior

Immunological Status to Hepatitis B Virus of Pregnant Women in Dakar, Senegal

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Open Journal of Immunology 2017年第2期7卷 37-44页

作者： Maguette Sylla Niang Khadidiatou Sarr Fall Babacar Mbengue Moustapha Mbow Ndiokhor Nd. Diouf Ousseynou Boye gora Lo Papa Madieye Guèye Rena Derwiche Amina Sow Sall Tandakha Ndiaye dieye Alioune dieye Service of Immunology Faculty of Medicine Pharmacy and Odontology (FMPO) Cheikh Anta Diop University of Dakar (UCAD) Dakar Senegal Laboratory of Medical Biology General Hospital of Grand-Yoff Dakar Senegal Department of Biological and Pharmaceutical Applied Sciences Pharmacy and Odontology (FMPO) Cheikh Anta Diop University of Dakar (UCAD) Dakar Senegal

Objective: Evaluate the immunological status to hepatitis B virus of Senegalese pregnant women by screening HBs antigen. Material and methods: The selection criteria of women were presence at the laboratory for biological exams of pregnancy follow-up. All volunteers for the study were screened for HBs antigen (HBs Ag). Investigation of chronic hepatitis B markers (HBe Ag, anti-HBe, viral quantification) was performed in HBs Ag positive participants. The concentration of anti-HBs antibodies was assessed in HBs Ag negative women. Results: One hundred and fifteen (115) pregnant women were included in the study from July to October 2014. The mean age was 29 ± 6 years, ranging from 16 to 47. The seroprevalence of HBs Ag was 12% and the majority of women (90%) were not vaccinated. Any of the 14 HBs Ag-positive subjects did not express serum HBe Ag, (marker of active viral replication) and all were positive for anti-HBe antibodies. Their viral load (HBV DNA) was undetectable and serum transaminases were normal. The anti-HBs antibodies titrated in HBs-Ag negative women serum revealed that only 46 had protective levels against HBV whilst 55 of them were unprotected.

关键词： HBs Ag Pregnancy Senegal

Rehabilitation of Mining Sites: The Case of the gora/Sabodala Gold Mine in Senegal Prospects for Sustainable Development of a Mine

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Journal of Environmental Protection 2021年第10期12卷 784-807页

作者： dieye Pathé Mall Ibrahim Samb Mansour Ndong Robert Institut Africain de Management Dakar Senegal Amadou Makhtar Mbow University Dakar Senegal Geology and Hydrogeology Applied to Mines and Major Civil Engineering Works Dakar Senegal Environment Department at Sabodala Gold Operations Dakar Senegal

The southeastern part of Senegal, in West Africa, is home to the country’s first major gold mine owned by Sabodala gold operations SGO, as subsidiary of Teranga Gold Corporation during the timeframe of this study. As part of its expansion, the company opened and operated the gora satellite mine for 4 years’ exploitation. At the end of the mine’s life, the authorities decided to close the site. In this context, SGO in compliance with its legal, regulatory and normative obligations, has commissioned a study of rehabilitation activities for a better environmental and social management of the gora gold mine. This study is a first in Senegal and presents the general framework for the rehabilitation of a gold mine which will allow scientists to have several research perspectives in this field. The methodological approach consisted of a participatory process of collecting field data and data from stakeholders directly involved in mine rehabilitation and closure;these data were analyzed and coupled with international best practices in rehabilitation, closure, and post-mine management. Results of the selected options are based on known experiences from around the world, coupled with analysis of the SGO’s field activities results and those obtained from the synthesis of the interview guides from the numerous consultations. This synthesis made possible to align them with international guidelines presented in this document. In this context, the aspects related to the open-pit mine equipment, processing facilities and related infrastructure were a particular interest to the various stakeholders. Thus, the following rehabilitation options were retained by the group constituted by the populations: 1) Backfilling pits, for cultivation practices and development of agribusiness and the establishment of grazing land for livestock;2) Setting up water storage basins for the sustainable development of certain activities around the mine and aquifer recharge while respecting the protection

关键词： Rehabilitation Mine Closure gora Sabodala Environment Sustainable Development