West Africa InterPore Chapter Meeting & Symposium

27 Oct 2023, 08:00 → 28 Oct 2023, 17:00 Africa/Accra

Bi Tié Albert GOULA (Université Nangui Abrogoua, Côte d'Ivoire)

FIRST SYMPOSIUM OF THE WEST AFRICA INTERPORE CHAPTER

Special Topic: Mining activities in Africa, mining waste management

The West Africa InterPore Chapter (WAIC), a national chapter of the International Society for Porous Media (InterPore), was founded in October 2022 by researchers from West African countries. The aims of the chapter are to connect West African scientists, engineers, and lecturers working in the field of porous media with each other and with the InterPore community; help improve the international visibility of West Africans in the field of porous media and promote the mobility of young researchers as it pertains to international conferences or research-exchange programmes.

For the first edition of its annual meeting, WAIC invites researchers and industry professionals to submit abstracts for the upcoming symposium. This symposium aims to address the pressing challenges associated with mining activities in Africa, particularly the critical issue of mining waste management. 

Mining operations in Africa face significant environmental and health concerns due to improper disposal and containment of mining waste. The contamination of soil, water bodies, and ecosystems poses serious risks to biodiversity and local communities. 

Porous media research and engineering offer valuable solutions to tackle these challenges. By studying the behavior of fluids and contaminants in porous materials, researchers can contribute to developing innovative waste management strategies. This includes the design of effective containment systems, the development of pollutant capture and treatment methods, and the optimization of porous media for filtration and remediation processes. 

This symposium aims to foster interdisciplinary discussions and collaborations among researchers, engineers, and industry stakeholders to explore the latest advancements and potential applications of porous media science and engineering in the context of mining waste management. 

We welcome abstracts that address topics such as 

• Porous media characterization
• Transport phenomena
• Reservoir engineering 
• Soil mechanics and engineering
• Heat and mass transfer
• Multiphysics & multiphase flow modeling
• Contaminant transport analysis
• Waste containment and remediation strategies
• Sustainable mining practices
• Social and environmental impacts of mining activities
• Process engineering 
• Other porous media applications

Join us in sharing expertise, research findings, and innovative ideas to address the challenges of mining activities in Africa and contribute to sustainable mining practices through porous media research and engineering. Together, let's strive for a more environmentally conscious and socially responsible mining industry. 

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Friday, 27 October

1 Mining Problems in Africa

Mining activities in Africa have significant environmental and health concern due to the improper disposal of mining waste. This waste contaminates soil, water and ecosystems posing a serious risk to biodiversity and local communities. To tackle these challenges, innovative waste management strategies are needed. In this study, heavy metals like copper, lead, and zinc from mining waste materials were bio-leach in a controlled bioreactors with Bacillus subtilis as metal binding bacteria. The pH, temperature, nutrient levels, and metal concentrations were determined by constant sampling. The measured concentration of heavy metals, was lead (Pb), copper (Cu), and zinc (Zn), with concentrations measured at 26.4 mg/kg, 8.55 mg/kg, and 91.79 mg/kg, respectively. The pH of the bioleaching system was adjusted and maintained at an acidic level (around pH 2) to create optimal conditions for the selected bioleaching microorganisms. The temperature was within 30°C to 50°C, ensuring that the temperature favored microbial activity with adequate oxygen supply was maintained throughout the experiment, supporting the microbial oxidation of metal sulfides. Over the course of the bioleaching process, regular sampling and analysis of the leachate indicated a substantial reduction in heavy metal concentrations. After 30 days of bioleaching, Pb concentrations decreased to 24.74 mg/kg, Cu concentrations decreased to 6.62 mg/kg, and Zn concentrations decreased to 86.88 mg/kg. Analysis of the solid residues revealed significant changes in mineralogy and chemical composition. X-ray diffraction (XRD) analysis showed the transformation of metal sulfides into less insoluble forms. In conclusion, the bioleaching experiment successfully reduced heavy metal concentrations in mining waste, making it a promising method for managing and remediating contaminated mining sites. This study suggests that further optimization and scale-up of this process could lead to environmentally friendly solutions for mining waste management.

2 Use of zero valent iron nanoparticle for in situ chemical reduction of hexavalent chromium in contaminated soils

In the environment, chromium is mainly found in two oxidation states: Cr(VI) and Cr(III). Cr(VI) is relatively mobile in the environment and is extremely toxic, mutagenic [1,2], teratogenic [3] and carcinogenic [4,5]. In contrast, Cr(III) exhibits relatively low toxicity [6] and is a necessary nutrient for humans and animals [7,8]. Therefore, the reduction of Cr(VI) to Cr(III) is environmentally friendly, and can be used for the remediation of Cr(VI) contaminated sites. Thus, the in situ chemical reduction of hexavalent chromium by the nanoparticle of zero valent iron (nZVI) in contaminated soils near a galvanic zone in northern Italy characterized by an excessive presence of Cr(VI) and other heavy metals has made the object of our research. Experiments were performed on soil samples collected from an industrial site where a nickel contamination, caused by a long-term productive activity, was also verified. The influence of reducing agents amount with respect to chromium content and the effectiveness of deoxygenation of the slurry were discussed. The soil was fully characterized before and after each test, and sequential extractions were performed to assess chemico-physical modifications and evaluate metals mobility induced by washing. Results show that the reducing agent successfully lowered the amount of Cr(VI) in the soil below the threshold allowed by Italian Environmental Regulation for industrial reuse. Cr(VI) reduction by colloidal nZVI proved to be effective: the civil reuse of soil [Cr(VI) < 2 mg/kg] was only achieved using colloidal nZVI within 60 min adopting a nZVI/Cr(VI) ) molar ratio of 30. The reducing treatment resulted in an increase in the amount of chromium in the oxide–hydroxide fraction,thus confirming a mechanism of chromium-iron hydroxides precipitation. In addition, a decrease of nickel (Ni) and lead (Pb) content in soil was also observed when acidic conditions were established.
Keywords: Hexavalent chromium, Contaminated soil, Chemical reduction, Nano zero-valent iron.
Références
[1] Bianchi V., Zantedeschi A., Montaidi A., and Majone F., 1984. Trivalent Chromium is Neither Cytoloxic nor Mutagenic in Permealized Hamster Fibroblasts. Toxicol. Lett., 23: 51-59.
[2] Beyersmann, Koester D.A., Buttner B., and Flessel P., 1984. Model Reactions of Chromium Compounds with Mammalian and Bacterial Cells. Toxicol. Environ. Chem., 8:279- 286.
[3] Abbasi S.A., and Soni R., 1984. Teratogenic Effects of Chromium(VI) in the Environment as Evidenced by the Impact of Larvae of Amphibian Rand tigrina: Implications in the Environmental Management of Chromium. Int. J. Environ. Studies, 23:131-137.
[4] Mancuso T.F., and Heuper W.C., 1951. Occupational Cancer and Other Health Hazards in a Chrome Plant. A Medical appraisal. L Lung Cancers in Chromate Workers. Ind. Med. Surg., 20:358-363.
[5] One, B.-L, 1988. Genetic Approaches in the Study of Chromium Toxicity and Resistance in Yeast and Bacteria. IN: Chromium in the Natural and Human Environments, (J.O. Nriagu and E. Nieboer, editors). John Wiley& Sons, New York, 20: 351-368.
[6] van Weerelt M., Pfeiffer W.C., and Fiszman M., 1984. Uptake and Release of 51Cr(VI) and 51Cr(III) by Bamacles. (Balanus sp). Mar. Environ. Res., 11:201-211.
[7] Vainshtein M., Kuschk P., Mattusch J., Vatsourina A., Wiessner A., 2003. Model Experiments on the Microbial Removal of Chromium from Contaminated Groundwater. Water Res., 37:1401–1405.
[8] Costa M., Klein C.B., 2006. Toxicity and Carcinogenicity of Chromium Compounds in Humans. Crit. Rev. Toxicol., 36(2):155–163.

Speaker: Mr Mouhamadou Thierno Gueye (Cheikh Anta Diop University of Dakar)

Gueye_Abstract.docx

3 Enhancing Precipitation Data Accuracy in Burkina Faso: A Comparative Analysis of Satellite-Based Products and Ground Measurements, with Soil Moisture Integration

Speaker: Dr Marcel Bawindsom Kebré (Université Joseph Ki Zerbo · Physique)

4 Advanced Characterization of Disordered Mesoporous Solids

Speaker: Dr Henry ENNINFUL (Universität Leipzig)

5 Fluid Phase Equilibria in Geometrically Disordered Mesoporous Materials

Speaker: Dr Henry Enninful (Universität Leipzig)

6 Energy recovery from low-value agricultural residues for biochar production during cooking using a multifunction family oven

Speaker: Dr Moussa dit Corneille TARPILGA (Laboratoire de Matériaux, Héliophysique et Environnement (LAMHE))

7 Phosphates from the Kotchari deposit, Burkina Faso.

Samples of phosphorites from different occurrences of the Kotchari deposits, Burkina Faso, were studied. They are phosphorites that are fine-grained with small quantities of clay. The chemical analyses by XRF indicate a CaO content of 35.98 to 41.33 wt%. and a P2O5 contents of 26.85 to 30.75 wt%.

The XRD patterns shows that the major phases are Carbonate-Fluorapatite (Francolite), Hydroxyapatite and alpha-Quartz. They coexist with minor phases that are Wavellite and Maricite. Small quantities of phyllosilicates, smectite and Illite, are also detected. The quantities of phases were obtained by Rietveld refinements with the MAUD software, using reference phases from usual databases. The obtained fits are satisfactorily, although the significant occurrence of peaks overlapping and broadening. In this study, quantitative Rietveld analysis has shown its effectiveness in accurately identifying and quantifying the mineralogical composition of phosphorites.

FTIR analyses further validate the identification of mineral phases. They show typical bands from phosphates groups in structures. Bands of carbonates groups are also detected and a band is correlated with the occurrence of structural F in Francolite. The relative Intensities of some bands from P-O bonds are related to the crystallinity index of main phosphate minerals. Values of the crystallinity index are slightly above the medium values, that is correlated with the partial substitution of carbonate groups in phosphate crystallographic sites, and with the occurrence of structural Fluor ions. The economic importance of the Kotchari deposits for soil fertilization in agriculture is recognized, and they were the subject of successive mapping and survey works. However, the medium crystallinity index is a disadvantage since it reduces the kinetic of phosphor assimilation in agricultural soils, needing complementary researches.

Speaker: Mr Jean baptiste ZOUNGRANA (PhD)