Environmental Geochemistry of the Upper Moulouya
Lead District abandoned mines (Morocco)
Argane 1, 2, 3, R. Hakkou 1, 2 and M. Benzaazoua 3, 4
1. Laboratoire de Chimie des Matériaux et de l’Environnement, Faculté des Sciences et Techniques, Université
Cadi Ayyad, Marrakech, Maroc
2. IDRC Research Chair in Management and Stabilization of Mining and Industrial Wastes, Faculté des
Sciences et Techniques, University Cadi Ayyad, Marrakech, Morocco
3. Laboratoire de Génie Civil et d’Ingénierie Environnementale, INSA de Lyon, Bâtiment Sadi Carnot, 9 rue de
la Physique, 69621 Villeurbanne, France
4. UQAT, 445 boulevards de l’université, Rouyn-Noranda, Québec, Canada
Abstract
Developing countries with important mining industries are increasingly concerned with the
impacts of mining on the environment. This preoccupation is omnipresent from the mineral
exploration until mine closure. Morocco, a country with a long mining tradition, has
experienced intense mining activity over the past centuries because of the richness and
diversity of its mineral resources. The mining sector is therefore a mainstay of Morocco's
economic and social development. However, the past mining activities generated large
volumes of waste rocks and concentrator tailings without any security and environmental
protections.
To reduce the negative impacts produced by mine sites in Morocco on the surrounding
environment, strong efforts must be engaged to sensitize stakeholders (citizens, government
and mining companies) and to develop effective control and restoration method and strategies
of mine sites rehabilitation.
One of the biggest abandoned mine sites of Morocco belong to the upper Moulouya district. It
constituted one of the largest lead deposits of Morocco, with a total output of more than 1
million metric tons. This region is crossed by one of the largest Moroccan rivers (the
Moulouya) and is composed of three main lead–barite deposits: Zeida (period of active
exploitation: 1972–1985), Mibladen (period of active exploitation: 1936–1985) and Aouli
(period of active exploitation: 1926–1985).
Mining activity has critically modified the natural landscape of the upper Moulouya region,
essentially around the abandoned mines of Zeida and Mibladen. In these sites, more than 20
million tons of mine tailings were accumulated in tailings ponds, located along fluvial banks
without any confinement and no pollution control. This region is also characterized by high
temperatures and strong winds enhancing erosion and transport of mine tailings.
Currently the area is characterized by a low population density (less than 20 inhabitants per
km2), poor economic conditions and only limited studies have been undertaken to acquire
information about contamination especially the one related to heavy metals within the mine
tailings effluents.
This study focuses also on investigating the geochemical behavior of Zeida and Mibladen
mine tailings to provide the baseline data required to assess metal mobility. For that goal, the
study was based on a multidisciplinary characterization of the tailings using both static and
kinetic prediction tests as environmental assessment tools.
Preliminary results of mine tailings characterization show the presence of Lead and Zinc as
relatively high amounts (Pb 5100 ppm and Zn 230 ppm). Total sulphur is ranging from 0.78 to
1.25 wt % and is mostly present as baritic sulfate. The main mineral phases consist of
dolomite, quartz and barite. Static test results PNN net are around 5 kg CaCO3/t. Leachate
analysis from kinetic tests showed near-neutral pHs, small conductivity values and very low
concentration of heavy metals (Pb 2 ppm) for the duration of the test.
Keywords: Abandoned mine tailings, Upper Moulouya mining district, leaching tests, lead,
Morocco.