INNOVATIVE APPROACHES TO MINERAL EXPLOITATION: THE CASES OF MANGANESE ENRICHMENT AND PYRITE RECYCLING
Creators: name: KASTRATI, SHPETIM
Publisher: name: Universit� degli Studi di Milano
Year: 2013

description: Turkey is an important manganese ore producer and a major target for new manganese deposits exploration. The two Mn deposits prospected for the present work are Mn-rich lenses within the melange zone of the Eski?ehir ophiolite and the Manisa metamorphic deposit. Both deposits are subeconomic due to the relatively low Mn content but underwent metamorphic textural and mineralogical modifications that could allow applying separation techniques to produce a final commercial Mn concentrate. The Eski?ehir ophiolite is located in the western part of the Izmir-Ankara-Erzincan Suture Zone (IAESZ) that crosses Turkey from the west (Izmir area) to the east (border with Georgia) (Uysal et al., 2009). Manganese deposits within the IAESZ are classified by Ozturk (1997) as radiolarian chert-hosted deposits. They are related to Neo-Tethyan suture and form the epi-ophiolitic sediment succession together with associated radiolarite, radiolarian chert, siliceous shale and brown claystone. The deposits show high Mn, variable Si and low Al contents and, as a rule, cannot be enriched due to their very fine grain size.. The Taycilar Mn deposit has never been mined and the local geology is not well known due to paucity of outcrops and absence of investigation. Mn-rich rocks are different from those typical of manganese deposits within IAESZ having undergone a strong metamorphic overprint, and now they consist of strongly deformed braunite-rich quartzites, with NW-SE trend of layering. Mineralogy and texture of the Taycilar deposit show conditions that can favour magnetic enrichment of ore at relatively coarse grain size, providing the opportunity to produce a high grade sand final product. Braunite shows a paramagnetic behaviour that is strongly affected by incorporation of elements, like Mg and Fe, substituting Mn. In addition the Taycilar deposit shows a metamorphic recrystallization with grain size increase that allows significative separation of Mn-rich phases and quartz at relatively coarse grainsize of crushed ore. For the experiment two samples, about 25 kg each, were taken from two outcrops and mixed in equal proportions. Ore was crushed at grain size 95 wt% +4 mm and 100% -20 mm. Magnetic separation tests were carried out with a Permroll dry magnetic separator at University of Eskisehir, using constant roll speed and magnetic field. Two tests were done for this experiments. Mn enrichment is respectively 6.55 wt% and 4.86 wt% for ESK2C and ESK10C, that corresponds to 8.46 wt% and 6.28 wt% on a MnO basis, respectively. Mn recovery is very high for ESK2C, 93.7 %, and much lower for ESK10C, 77.7 %. In conclusion tests show that braunite-rich metamorphic manganese deposits can be successfully enriched magnetically, with a metal recovery that is inversely correlated to grain size. Minimum grain size is hence chosen on the basis of crushing costs and market demand. Manisa manganese deposit shows a texture with relatively large scale Mn-rich and Mn-poor domains, differently from typical fine grained homogeneous Mn deposits within cherts. This texture can allow gravitational enrichment of the ore due to the high liberation that can be attained through comminution. To test the feasibility of such enrichment a stock of 10 Mt of run of mine was taken to a 5 km away enrichment plant, that comprises a jaw crusher, a ball mill, a jig and two shaking tables. Jig final concentrate has 46,76 wt% Mn while concentrate from tables is poorer (around 38,6 wt% Mn). That is because at millimeter scale the jig works very well and the grains have a good grade of liberation. The final concentrate, resulting from mixture of jig and table concentrates has a good commercial quality, with 45,04 wt% Mn, where 70,97 wt% of the material comes from the jig and only 29,03 wt% from the tables The separation efficiency is 70,60 %. As a conclusion, according to this test, Manisa Mn ore can be successfully enriched at a grain size - 6 mm. Pyrite (FeS2) is one of the most ubiquitous minerals of the earth crust. It is found in igneous, metamorphic and sedimentary rocks and crystallizes at both high and low temperatures. Pyrite was widely used in the past for the production of sulfuric acid, but nowadays this use is limited to China and pyrite lost its value as an industrial mineral. The present work deals with projects for the extraction of pyrite in Albania and Kosovo for new industrial applications that re-opened pyrite market. For the projects three different ways to recover pyrite were considered: a) as a by-product of pyrite-bearing active mines (Trep�a, Kosovo; Fusharrez, Albania); b) re-opening abandoned pyrite mines used in past for sulfuric acid production (Spa�, Albania); c) exploitation of a new pyrite deposit (Lunik, Albania). Pyrite is an important sulfide phase in the active lead and zinc Trep�a Mine, Kosovo. Trep�a Belt belongs to the Kosovo sector of the Serbo-Kosovo-Macedonian-Rhodope Metallogenic belt of Oligocene-Miocene age, which includes base and precious-metal districts in Kosovo, southern and western Serbia, northern Greece and southern Bulgaria (Heinrich and Neubauer, 2002). In northern Albania pyrite can be recovered within the Mirdita ophiolite belt, in similar geological settings, as a by-product and from the tailings of the Fusharrez copper mine and from the abandoned Spa� pyrite mine. Mirdita is located in the Jurassic age Mirdita-Pindos ophiolite belt of Albania-Greece that ranges from ultramafic to mafic rocks with a number of andesitic and felsic volcanic domes in the central portion. The volcanic rocks are overlain by a sedimentary melange (Beccaluva et al., 1994). Finally in eastern Albania the never exploited Lunik pyrite deposit is placed inside volcanic rocks. It was formed underwater together with pillow basalts and at low temperature hydrothermal conditions. The demanding quality parameters for the new industrial applications concern grain size (90% between 10 and 50 mm), S content (48 +/- 2 wt%) and Fe (above 44 wt%). The preliminary study of the above mentioned deposits led to rank them in order of decreasing geologic, technical and logistic feasibility. The application of the results led to begin exploitation at Spac abandoned mine where about 1000 MT of pyrite ore were taken and exported to Italy in 2012.