Συγκριτική ορυκτολογική και γεωχημική μελέτη Ελληνικών και τροπικών Βωξιτών
Περίληψη
Bauxites as residual formations are almost the only source of aluminum. For many decades, the economy of Greece and Europe's largest economy was based on the exploitation of bauxites for the purpose of aluminum production. The bauxites are formed in the process of lateritic disintegration. A process quite complicated. Depending on the area they are located, they have different characteristics. Since the 1970s and 1980s, more intensive research has begun to make a full understanding of the bauxite deposits. The first was used by French geologist Pierre Berthier to describe the residual formations found in Les Baux-de-Provence in southern France. Then followed Bushinsky (1958), Valeton (1972) and Bardossy (1982). In Greek bauxites, research was easier as the samples were compact and hard enough. Greek bauxites are characterized by oolithic tissue and texture. They are white to ash-colored. Their main minerals are boehmite and diaspore. In addition, they include chromite with a variation of 49.7-65.48 % w/w Cr2O3. They contain zircon, the chemical composition of which comprises about 32-33 % w/w SiO2 and 63.8- 66.88 %w/w ZrO2 while the scandium oxide was observed to be 2.73% by weight Sc2O3 in zircon. Ilmenite in the Greek bauxites is characterized by 49.91% by weight to 50.58% by weight TiO2, 45 % w/w FeO and about 1.49% w/w MnO. Finally, the rutile contained in the samples of the Greek bauxites is characterized by over 90 % TiO2 and low tungsten (W) contents up to 1% by weight. WO3, tantalum (Ta) 0.2 to 1.90% by weight Ta2O5 and niobium (Nb) 0.4 to 0.97 wt%. Nb2O5. The tropical bauxites are red in color due to the intense oxidation they have suffered. They are fairly brittle and soft. The main mineral of tropical bauxites is the gibbsite. However, there are times where it may contain low rates of boehmite. Chemical analyzes were not feasible as the samples were covered with iron oxides and the results would not be representative. From the study of the above it is concluded that although these are apparently for the same deposit, these two types differ histologically, mineralogically and geochemically. Therefore, for each bauxite deposit, it would be good to interpret the way of genesis first, since it is the most important factor in shaping the above characteristics.
Πλήρες Κείμενο:
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