Zeolites in the northern part of the Evros Prefecture
Electron microscope image (x40,000) of zeolite (clinoptilolite)
The best-known zeolite region in Greece is in the northern part of the Prefecture of Evros, with the zeolite formations extending into Bulgarian territory, where they are being extensively mined by a Greek company, whilst on Greek territory there is no mining activity whatsoever, as the Greek company’s efforts to acquire mining rights have become embroiled in a long-running legal disputeregarding the acquisition of exploitation rights.
It should be emphasised here that extensive and successful research into the applications of Greek zeolites has been carried out by the Professor of Geology at the Aristotle University of Thessaloniki Mr A. Filippidis.
Following geological surveys, OLYMPOS identified another area outside the claimed one and applied for an Industrial Minerals Exploration Licence, which is expected to be granted.
Numerous hand-samples were taken from this site, the mineralogical analysis of which revealed a clinoptilolite content of 75 per cent in a typical sample, as determined by the Mineral Lab (Colorado, USA), and an ion-exchange capacity (CEC) of 135 meq/100 g (in the same sample with a particle size distribution of 0–1 mm) as determined by the laboratory of the Department of Geology, School of Mineral Resources Engineering, University of Crete.(127 meq/100 g according to the Hazen Laboratory in Colorado, with a particle size distribution of 0.3–0.85 mm) The average of three representative samples yielded a cation exchange capacity (CEC) of 123 meq/100 g for material with a particle size of 0–1 mm and 130 meq/100 g for material with a particle size of 0.3–0.85 mm, from Crete and Colorado respectively, with a striking agreement between the results of the two laboratories. It should be noted that both laboratories report relatively low CEC values for theand used in Greece, which originates from a neighbouring country (70 meg/100 g according to Hazen and 85 meg/100 g by the University of Crete, based on random samples from sacks available on the market).
With regard to fieldwork, the area to be licensed will be investigated through appropriately planned excavations based on a geological and mineral resources study that has already been carried out. The samples from the excavations will be analysed to identify clinoptilolite or any other minerals belonging to the zeolite group, as well as their respective ion-exchange capacities. If, by that time, drilling is permitted in areas operating under Standard Environmental Commitments (New Quarrying Act), a network of boreholes will obviously be established.
Based on the data from the exploration work, OLYMPOS will proceed to the next stage of the lease – the operating licence – in accordance with current legislation.
It should be particularly emphasised that the OLYMPOS plant is ready for fully integrated processing of zeolites, with the capacity to produce any particle size fraction up to ultra-fine – 10 μ. material, with the added advantage of iron-free grinding.
The success or failure of the entire project will depend to a large extent on the time required for the various stages of the administrative procedures.
The samples were surface-hand-collected from within the 99 stremmas polygon, and the following procedure was followed. Twenty blind (non-selective) samples were grouped within the same stratigraphic horizon. Each of the above samples weighed approximately 1 kg and consisted of pieces measuring approximately 5–10 cm. The samples were transported to the OLYMPOS (formerly MEVIOR), where each was passed separately through a counter-rotating cylinder crusher. After repeated passes, a particle size of <1 mm was achieved. The samples crushed in this manner were then mixed in a manual sample mixer (a practical yet useful tool that achieves representative sampling without the subjective factor —it has replaced the old cross-sampling method), from which a final representative sample of 40–50 grammes. A slight particle size differentiation was carried out by sieving on a laboratory vibrating sieve to obtain three particle size fractions for the determination of the ion-exchange capacity: <1 mm for the Technical University of Crete and 0.3–0.8 mm and <0.3 mm for the HAZEN Laboratory in Colorado. The sample was sent to the Mineral Lab for mineralogical analysis without undergoing the aforementioned sieving.