Rachid Hakkou

Phosphate sludge: thermal transformation and use as lightweight aggregate material.

Phosphate sludge generated from beneficiation plants of Moroccan phosphate rocks was investigated at 900-1200 °C by X-ray diffraction, scanning electron microscopy, thermal analysis and Fourier-transform infrared spectroscopy. Mixtures of the phosphate sludge and a swelling clay (up to 30 wt.%) were investigated and their properties (shrinkage, density, water absorption and compressive strength) were measured as a function of temperature and clay addition. The results showed that gehlenite neoformed from lime of decomposed carbonates and breakdown products of clay minerals and that fluorapatite (original mineral) resisted heating until fusion. The measured properties were mainly controlled by temperature, and the effect of clay addition was less regular, except for water absorption. Considering the mixtures densities (1.44-3.02 g/cm(3)), lightweight agglomerates can be produced at 900 or 1100 °C, but their compressive strengths were relatively low (2-4.5 MPa). Based on SiO2-Al2O3-Fluxes diagram and taking account of the chemical composition of the materials used, the production of expanded aggregates requires clay additions as high as 80 wt.%.

Impact of human activities on the physico-chemical quality of surface water and groundwater in the north of Marrakech (Morocco).

The aim of this study was to assess the impact of three sources of pollution (landfill leachate, wastewater and mining activities) on the physico-chemical characteristics of surface water and groundwater in the northern region of Marrakech (Morocco). Numerous groundwater samples and surface water (Tensift River) samples were collected during the dry season and analysed. The groundwater samples had a high conductivity, which varied between 0.95 and 7.40 mS/cm; the conductivity of the surface water samples varied between 1.31 and 15.84 mS/cm. pH varied between 6.64 and 8.10 for groundwater and between 6.70 and 8.40 for surface water. The results showed that groundwater and surface water had a degraded quality in the region. Principal component analysis (PCA) enabled identification of the impact of pollution sources by combining the upstream and the downstream points. These results also showed that, in the study area, the effect of wastewater and the mine were dominated those of the landfill.

Assessment of Trace Elements in Soils and Mine Water Surrounding a Closed Manganese Mine (Anti Atlas, Morocco)

Five mine water samples, 23 topsoil samples, and four mine waste (tailings) samples were collected to assess the effects of a closed Moroccan Mn mine. Based on the pH, electrical conductivity, and concentrations of sulphate, Cu, Zn, As, Cd, Pb, and Mn, mining has not adversely influenced mine water quality. Soil samples were analyzed for 23 chemical elements and the results were interpreted by univariate and multivariate statistical techniques. Based on an enrichment factor (EF) calculation, only Cd, As, V, and Mn were selected for further study. Geochemical background (GB) and geoaccumulation index (Igeo) were determined for these elements to differentiate between geogenic and anthropogenic enrichment. The GB values showed that the Tiwiyyine soils contained a high geogenic content of Cd, As, V, and Mn that reflected the geochemistry of the parental rocks in this mineralized region. The Igeo calculation revealed that these soils were moderately influenced by anthropogenic activity, which had increased the concentrations of those elements. Finally, geochemical maps revealed that mining was likely responsible for the anthropogenic soil pollution.Zusammenfassung5 Grubenwasserproben, 23 Proben des Oberbodens und 4 Tailingsproben wurden genommen, um die Auswirkungen eines marokkanischen Manganbergwerks zu bewerten. Ausgehend von pH-Wert, elektrischer Leitfähigkeit und den Konzentrationen von Sulfat, Cu, Zn, As, Cd, Pb und Mn hat der Bergbau die Wasserqualität nicht negativ beeinflusst. Die Bodenproben wurden auf 23 chemische Elemente untersucht. Die Ergebnisse wurden mittels uni- und multivariater statistischer Methoden bewertet. Basierend auf der Berechnung eines Anreicherungsfaktors (EF) wurden nur Cd, As, V und Mn in die weiteren Betrachtungen einbezogen. Um zwischen geogener und anthropogener Anreicherung zu unterscheiden, wurden der geologische Hintergrund (GB) und der Geoakkumulalationsindex (Igeo) für diese Elemente bestimmt. Die geogenen Hintergrundwerte zeigten, dass die Böden von Tiwiyyine hohe geogene Gehalte an Cd, As, V und Mn haben, die die Geochemie des Muttergesteins in dieser erzreichen Gegend widerspiegeln. Die Berechnung des Igeo erbrachte, dass menschliche Aktivität diese Böden mäßig beeinflusst und die Konzentrationen der genannten Elemente erhöht haben. Geochemische Karten zeigten, dass diese anthropogene Bodenkontamination wahrscheinlich durch den Bergbau verursacht wurde.ResumenSe colectaron 5 muestras de agua de mina, 23 muestras de suelo superficial y 4 muestras de colas para analizar los efectos de una mina de manganeso actualmente cerrada. En base a las medidas de pH, de conductividad eléctrica y de las concentraciones de sulfato, Cu, Zn, As, Cd, Pb y Mn, se puede concluir que la minería no ha afectado la calidad del agua de mina. Se analizaron 23 elementos quimicos en las muestras de suelos y los resultados fueron interpretados por técnicas estadísticas univariantes y multivariantes. Basados en los cálculos del factor de enriquecimiento (EF), sólo Cd, As, V y Mn fueron seleccionados para estudios posteriores. El fondo geoquímico (GB) y el índice de geoacumulación (Igeo) fueron determinados para estos elementos para diferenciar entre enriquecimiento geogénico y antropogénico. Los valores GB mostraron que los suelos Tiwiyyine contenían un alto contenido geogénico de Cd, As, V y Mn que reflejaban la geoquímica de las rocas en esta región mineralizada. El cálculo Igeo reveló que los suelos estaban moderadamente influenciados por la actividad antropogénica que había incrementado las concentraciones de aquellos elementos. Finalmente, los mapas geoquímicos revelaron que la minería era probablemente responsable por la contaminación antropogénica de los suelos.摘要采集了5个矿井水、23个表层土和4个矿山固废(尾矿)样品评价摩洛哥小阿特拉斯山脉(Anti Atlas, Morocco)关闭锰矿(Tiwiyyine)的环境影响。矿井水的pH值、电导率及硫酸盐、Cu、 Zn、As、Cd、Pb、Mn的浓度分析表明采矿还未对矿井水质产生不利影响。运用单变量和多变量统计法分析了土壤样品的23种化学元素测试结果。基于富集因子(EF)分析,选取Cd、As、V及Mn进一步分析。通过地球化学背景值(GB)及地质富集指数 (Igeo)计算识别这几种元素的地质与人类富集成因。地球化学背景值(GB)计算结果表明Tiwiyyine土壤富含地质成因的Cd、As、V和Mn,反映了成矿区母岩的地球化学特征。地质富集指数(Igeo)计算结果表明土样已受到一定程度人类活动影响,这几种元素浓度已经增大。地球化学成果图显示采矿活动可能是耕作土壤受污染的原因。

Leaching and geochemical behavior of fired bricks containing coal wastes

High amounts of mine wastes are continuously produced by the mining industry all over the world. Recycling possibility of some wastes in fired brick making has been investigated and showed promising results. However, little attention is given to the leaching behavior of mine wastes based fired bricks. The objective of this paper is to evaluate the geochemical behavior of fired bricks containing different types of coal wastes. The leachates were analyzed for their concentration of As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Zn and sulfates using different leaching tests; namely Tank Leaching tests (NEN 7375), Toxicity Characteristic Leaching Procedure (TCLP) and pH dependence test (EPA, 1313). The results showed that the release of constituents of potential interest was highly reduced after thermal treatment and were immobilized within the glassy matrix of the fired bricks. Moreover, it was also highlighted that the final pH of all fired samples changed and stabilized around 8-8.5 when the initial pH of leaching solution was in the range 2.5-11.5. The release of heavy metals and metalloids (As) tended to decrease with the increase of pH from acidic to alkaline solutions while Mo displayed a different trend.