IMWA Proceedings 1999 | © International Mine Water Association 2012 | www.IMWA.info MINE, WATER & ENVIRONMENT. 1999 IMWA Congress. Sevilla, Spain CONVERSION OF QUARTZ-MINE WASTE MATERIAL TO EXPLOITABLE RESOURCES AND INDUSTRIAL PRODUCTS Nikolaos Arvanitidis\ Nikolaos Kaklamanis2 and Spyros Platias3 1 Institute of Geology and Mineral Exploration (IGME) Fragon 1 546 26 Thessalniki, Greece E-mail: [email protected] 2 Institute of Geology and Mineral Exploration (IGME) Messoghion 70 11527, Athens, Greece 3 ELVIOR S. A. Mitropoleos 77 54622, Thessaloniki, Greece e-mail: EL [email protected] ABSTRACT Northern Greece hosts a number of strategic industrial minerals which make an increasingly important part of the mining industry and commerce in Greece. Significant quantities of quartz-vein resources of varying quality are hosted by gneisses and schists mainly in Pre-Alpine metamorphic formations. The Greek mining company ELVIOR S.A. produces from its quarry and plant north ofThessaloniki, nearly 12,000 tpa, of which a pure white fraction of 3,000 tons is exported for polyester tile manufacturing (95% quartz and 5% polyester). A quartz powder (-200 mesh) of 2,000 tons is applied in fillers and ceramics industry and 7,000 tons have a local market for more conventional applications. The company is now developing a processing flow sheet for fluid inclusion removal, to produce ultrapure grades. Previous years quartz production led to stockpiling of about 200,000 tons of mine and processing tailings/by-products disposed as waste material. In the frame of an European Union funded project, mineral processing studies undertaken were focused on exploitation of quartz tailings/by-products to turn them into exploitable resources and commercial products. An industrial scale flow-sheet, including crushing, classification, grinding, attritor treatment, drying and magnetic separation was developed, to install a new processing plant, already in successful operation. In terms, of quartz tailings exploitation, whiteness and removal of iron content and mineral impurities (micas, chlorite, feldspars, iron oxides, sulfides) were attained to obtain industrial products. The recovery of marketable quartz from mine and processing tailings/by-products, except from solving an existing environmental problem and developing an almost zero-waste production line, it guarantees mine-life extension to another 15 years, in an area where quartz reserves are reported almost exhausted. The quality grades achieved to date, put already quartz in certain segments of the European and international market. 703 Reproduced from best available copy IMWA Proceedings 1999 | © International Mine Water Association 2012 | www.IMWA.info INTRODUCTION tion in Assiros processing plant (Figure 1). Some years ago Elvior faced the problem of mineable quartz resources, as Exploration for vein-quartz deposits, as well as evalua­ reserves in the Kastri quartz deposit were reported almost tion of known prospects, in northern (Macedonia, Thrace) and exhausted. Company's main interest, as an industrial partner in central (Thessaly) Greece has been carried out by the Institute the BRITE EURAM project, except from improving the quality of Geology and Mineral Exploration (IGME) of Greece, for the (high -to ultra- pure grades) of its final quartz products, was implementation of the BRE2-CT94-1 026 E.U. Brite - Euram II to locate new exploitable resources. Geological exploration and Programme entitled "New industrial applications for quartz feasibility evaluation led to discovery of potential quartz -vein deposits indigenous to the Community". This completed project deposits in northern and central Greece (Figure 1), where aimed at developing advanced exploitation techniques to pro­ mining is already in operation. About 3,000 tons of quartz ore duce ultra-pure quartz/silicon for high-tech application needs of have been produced. At the same time the development of a the European market, using Greek vein-quartz as raw material new processing flow sheet made possible the recovery of com· (Arvanitidis et al., 1988).Targets were subjected to a succes­ mercial quartz from stockpiled tailings/by-products, to provide a sion of geological, geophysical, petrological, geochemical, as cost- effective and easily accessible resource opportunity. well as trenching and drilling studies and tests which resulted in This communication will present industrially feasible the discovery of significant vein-quartz reserves amounting to dressing techniques succeeding to turn what is making today 2,5 m.t. and the selection of prime targets for further evaluation. mine and processing waste, to exploitable resources. Along with the completion of the project the achieved quartz qualities in terms of elemental chemical impurities (Fe, AI, Ti, GEOLOGIC SETTING Na and K) appear feasible for the optics industry. (Arvanitidis and Kilias, 1997). Quartz veins are hosted by rocks belonging Quartz vein mineralization of the Palaeozoic or older to the Serbomacedonian (SMZ), Pelagonian (PZ) and Rhodope SMZ occurs in its western lithostratigraphic and tectonic unit, (RZ) geotectonic Zones (Figure 1). the Vertiskos Formation (VF) (Figure 1). The VF is a NW-SE trending highly deformed and polymetamorphosed heterogene· ous assemblage consisting of metasedimentary two-mica e QuarU veins gneisses and garnet-, staurolite - and kyanite- bearing mica .& Quartz -feld.spar pegmatite veins 0 Quac-ry schists, meta-tholeiitic amphibolites, metagabbros, seprentini· zed ultramafics, anatectic granites and pegmatites (Kockel et al., 1977; Dixon and Dimitriadis, 1984; Sakellariou, 1989; Kou· rou, 1991; Sidiropoulos, 1991 ). Five metamorphic episodes (M1-M5) and four major deformation phases (D1-D4) have been recognized in the NW part of VF where most veins cluster (Figure 1) (Kourou, 1991; Sidiropoulos, 1991 ). The area has suffered Alpidic (Late Jurassic) deformation (D3) and regional metamorphism (M4) reaching upper greenschist facies condi· lions (T: 400-520 °C; P: 5-6 or 9 kb). This tectonometamorphic event was followed by post Jurassic deformation (D4) and retrogression under greenchist facies (M5) (T: 300-550 °C; P < 5kb). Post-D4 brittle phenomena have been ascribed to gra· dual uplift of the Vertiskos basement (Kourou, 1991; Sidiropou­ los, 1991 ). Evidence for Hercynian (Amplibolite Facies - M3-D2 and M2- D1) and pre-Hercynian (Eclogite Facies- M1) tectonic and/or metamorphic events exist locally. Figure 1. Quartz and pegmatite vein deposits, quartz mining and industrial operations VEIN GEOMETRY, MINERALOGY, in central Macedonia, N. Greece. DEFORMATION AND CHEMISTRY During the last 25 years, vein-quartz mining and pro­ cessing operation activities, undertaken by the Hellenic Indus­ Figure 1 shows the locations of the discovered and trial Minerals S.A. (known in Greece as ELVIOR S.A.), led to known veins of VF. Quartz veins routinely occur in two-mica stockpiling of about 200,000 tons of mine and processing tai­ gneisses and biotite gneisses occupying extensional fractures, lings/by-products, disposed nearby as waste material. Com­ except for rare cases when partly transect granitic bodies. They pany's quartz production was based on exploitation of a SMZ form disrupted and boudinaged steeply dipping (90° to 40°) quartz vein deposit in the Kastri quarry (Figure 1) and beneficia- bodies, striking NNW-SSE concordant to the regional schisto- 704 Reproduced from best available copy IMWA Proceedings 1999 | © International Mine Water Association 2012 | www.IMWA.info CONVERSION OF QUARTZ-MINE WASTE MATERIAL TO EXPLOITABLE RESOURCES AND INDUSTRIAL PRODUCTS sity. Veins measure from 30 up to 100 m in length, rarely rea­ fraction, were subjected to beneficiation selection tests. A flow ching 300 or 500 m; thickness vary from 3 to 15 m. Veins are sheet, including crushing, classification grinding, wet screening, composed chiefly of milky or yellowish - brown quartz (up to drying and dry magnetic separation (Figure 2) was developed 99,5% by volume) with traces of white mica, sulphides, feldspar to remove all mineral contaminants and to produce standard and iron oxides. The quartz grains are deformed, subhedral to grades meeting the specifications of the tiles (artificial stone) anhedral, elongated and slightly dimensionally oriented, with and ceramics industries. relative dimensions of up to 8 mm in their longest axis and up to 4 mm in width. Vein quartz has suffered : a) An early episode of ductile deformation (quartz 1), post-dating the vein filling, attri­ buted to emplacement of the veins in a dynamic tectonically active environment; b) Brittle fracturing that took place after the ductile deformation accompanied by cataclasis and recrystalli­ zation (quartz 2). SMZ raw quartz compositions show ranges of Fe= 1-28 ppm, AI= 22-73 ppm, Na = 12-37 ppm, K = 4- 28 ppm, ~0,1mm Ca = 11-40 ppm, Mg = 4-10 ppm, Ti = 1,4-4.8 ppm and Li =0,1-0,9 ppm. The problem for electronic high- tech applica­ tions of quartz arises from high Na contents, and Na appeared to be the hardest element to degrade to quality requirements by the purification techniques used to successfully eliminate other elements (i.e. Fe, AI, Ca, Ti). Chemical removal of fluid inclu­ sions and subsequent degradation to 2,39 ppm Na resulted to Magnetic Product substantial quality improvement of quartz. QUARTZ TAILINGS/BY-PRODUCTS COMPOSITION Quartz- mine operation and processing has been under­ taken in Northern Greece, by the Hellenic Industrial Minerals (Eivior S.A.), the last 25 years. During this