Phosphorite Deposits of North Africa

Phosphorite Deposits of North Africa


a group of phosphorite deposits in the Western Sahara, Morocco, Algeria, Tunisia, and the Arab Republic of Egypt. The deposits are located within the African Platform and the Atlas Hercynian and Alpine folded region, which extends for approximately 5,400 km. The total geological phosphorite reserves are about 50 billion tons, including the more than 7 billion tons that have thus far been explored.

The principal deposits are Bu Craa in the Western Sahara, Khouribga, Benguérir, and Youssoufia in Morocco, Djebel Onk in Algeria, Redeyef, Mrata, Moularés, Metlaoui, Sehib, M’dilla, Kaf-ash-Swair, and Kalaa Djerda in Tunisia, and Abu Tharthur, Mahamid, Abu Tundub, Nukhayl, Hamrawain, Umm Huwaytat, and Wasif in the Arab Republic of Egypt. The first deposits were discovered between 1885 and 1887. The deposits are confined to Upper Cretaceous, Paleocene, and Lower Eocene clay-silicon-carbonate beds; the beds in the Arab Republic of Egypt are primarily from the Upper Cretaceous period. Phosphorite-bearing deposits generally show signs of weak tectonic disturbance, with angles of dip of the phosphorite strata ranging between 5° and 25°.

Commercial deposits are represented by strata (2–6 m thick) of granular phosphorites of marine origin, 50–90 percent of which are composed of phosphate nodules and pellets admixed with phosphatized fauna, such as mollusks, foraminifers, reptiles, and fish. Phosphorite gritrock, conglomerates, and sands also occur. Phosphorite ores are classified according to the content of the useful component, in this case, P2O5, as rich (more than 28 percent), average (20–28 percent), and poor (less than 20 percent). Phosphorites are characterized by an elevated uranium content (0.005–0.07 percent) and, in many cases, elevated concentrations of rare-earth metals (up to 0.07–0.3 percent) and pyrite.

The deposits are worked by underground-mining and open-pit methods (nearly in equal proportion). In the period 1970–74 the phosphorite yield in North Africa rose from 15 million to 25.4 million tons, primarily because of increased production in Morocco.


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