Bou Craa

BOU CRAA (RU: Бу-Краа) is the unique deposit, according to the reserves of the rich phosphorites, at the north of the Western Sahara, within the Oued Iddahaba region. It has been discovered during the 1963, is being operated since the 1971. The phosphorite-bearing carbonate-clay-siliceous depositions (Maastrichtian-Paleocene) with the thickness of 30-50 metres, which are laying with slight inclination within the brachysynclinal structure of the western slope of the African craton, are overlain by the thin Oligocene-Quaternary proluvial formations. The phosphorites form two layers within the Lower Paleocene part of the cross-section: the lower layer (the thickness is approximately 1 metre), and the upper layer (the thickness is 4.5-6 metres), which are separated by the layer of the massive siliceous rocks (Figure).

The geological cross-section (west-east) of the Bou Craa phosphorite deposit:BOU CRAA, geological cross-section

  1. the modern alluvium;
  2. the conglomerate cover;
  3. the siliceous clays;
  4. the flint stones;
  5. the phosphorites.

There has the industrial significance the upper layer of the granular carbonatic phosphorites with the content of P2O5 of 30-33%. The reserves of the phosphorite ores are estimated at 10 billion tonnes, of which 1.7 billion tonnes have been explored and prepared for the opencast extraction, with the content of P2O5 of approximately 30%. The thickness of the overburden is 10-30 metres. The annual extraction is 0.40 million tonnes (1979). The development is conducted by the "Phos Bou Craa" company, which is representing mostly the united capital of Spain and Morocco. The ore, which has been extracted, is beneficiated by the mechanical method (crushing, washing, and dry classification), with the obtainment of the phosphorite concentrate (the content of P2O5 is 36.6%). The designed productive capacity of the enterprise is 10 million tonnes of the ore per year. The concentrate is delivered from the beneficiation plant of the deposit through the belt conveyor, with the length of 100 kilometres, with the throughput capacity of approximately 2 thousand tonnes of concentrate per hour, into the El Aaiún port onto the Atlantic coast. The export is performed into the countries of the Western Europe, and also into Japan, Brazil, and other countries.