Arabian-African phosphorite-bearing province

ARABIAN-AFRICAN PHOSPHORITE-BEARING PROVINCE (RU: Аравийско-Африканская фосфоритоносная провинция) is one of the largest provinces of phosphorites within the world, which is occupying the vast territory at the north of the Africa and Arabian Peninsula. The area of the Arabian-African phosphorite-bearing province is more than 9 million square kilometres. There are distinguished the following phosphorite-bearing basins: Moroccan, Algeria-Tunisian, Middle Eastern, Western Saharan, Mali-Nigerian, Senegalese, Togo-Nigerian, Congolese, with reserves of phosphorites of 75 billion tonnes, including at least 26 billion tonnes of the explored ones (1981). The largest deposits of phosphorites are the Khouribga, Ben Gerir and Yusuf (Morocco), Bu Kraa (West Sahara), Jebel Onk (Algeria), Abu Tartur (Egypt), Al-Hasa (Jordan), and Eastern (Syria) ones. The largest reserves of phosphorites are concentrated within the Morocco, Western Sahara, Egypt, and Tunisia.

The first facts about the phosphorite manifestations have been obtained during 1885 for the Algerian-Tunisian and Egyptian basins, during 1908-11 for the Moroccan and Eastern Mediterranean basins, during the 30s for the Senegalese and others. The industrial usage of the deposits of the province is conducted since the start of the 20th century. The development of the deposits has gained the greatest momentum during the 70s-80s. The deposits are represented with the grainy phosphorites, which are associated with the depositions of the Upper Senonian, Paleocene, and Eocene, on the area of the large tectonic structures of the peripheral parts of the pre-Cambrian African-Arabian platform, and of the young Atlas epi-platformal folded region.

There is characteristical the near paragenetic association of the layered depositions of the grainy phosphorites (the thickness is 1-11 metres, sometimes more) with carbonatic, siliceous, and argillaceous rocks. Phosphorites and their host rocks belong to the shallow water formations of the epicontinental seas of the oceanic basins, namely, of the Tethys and Atlantic ones. There served as the regions of the greatest phosphorite formation of the late Senonian and Paleogene epochs the extensive latitudinal and meridional depressions on the slopes of the platformal basement. Most of the deposits of the eastern part of the province (Egypt, Syria, Jordan, and other countries of the Middle East) are associated with the upper Campanian and lower Maastrichtian depositions. There are characteristical for the western part of the province (Morocco, Algeria, Tunisia, West Sahara, Senegal, Togo) the Maastrichtian-Paleocene and Eocene age of the phosphorites. They distinguish among the ores the rich ones (more than 28% of P2O5), medium-grade ones (20-28% of P2O5), and low-grade ones (less than 20% of P2O5). The ores mostly contain uranium (0.005-0.07%), sometimes contain the increased concentrations of the rare earth elements (0.07-0.3%). The deposits of the rich and medium-grade ores within the Arabian-African phosphorite-bearing province with the total volume of the extraction of approximately 36.8 million tonnes (1980) are developed using the open pit and underground methods. The phosphorites of the province undergo the beneficiation with mechanical methods (crushing, drying, and so on), and to the calcined roasting with the obtainment of the commercial concentrates with 30%-36% content of P2O5. The largest part of the phosphorites, which are extracted within the Arabian-African phosphorite-bearing province, is exported. The largest suppliers of phosphorites onto the international market (mainly into the countries of the Western Europe) are Morocco, Jordan, Togo, Tunisia, Israel, Senegal, Syria and Algeria.