Mineral processing of low quality zircon concentrates and preconcentrates S. Sabedot 1 , H. Wotruba 2 , C. H. Sampaio 3 , C. O. Petter 3 and I. A. S. de Brum* 3 In NE Brazil, Millennium Inorganic Chemicals do Brasil S/A produces zircon concentrates with variable contents of ZrO 2 . One of such concentrates, named zirconite B, presents a low ZrO 2 value and high content of contaminants, being considered as a low quality concentrate. The deposit consists of coastal dunes, and the minerals are located in the base, coated by a clayey– ferruginous pellicle, which interferes in the zircon beneficiation. Besides, two other causes influence the production of the low quality concentrate: mineral inclusions and the development of metamictes in the zircons. The present work, conducted on the zirconite B concentrate and in the preconcentrate, characterises the pellicle’s nature, identifies the mineral inclusions in the zircons, illustrates the occurrence of metamictes in the zircons and suggest alternative routes to the production of a high quality zircon good, from the zirconite B concentrate and the zircon’s preconcentrate. Keywords: Mineral processing, Zircon, Ilmenite, Tailings Introduction The zircon is an accessory mineral in a variety of igneous rocks, especially in those containing sodic feldspars, such as granite, senate and diorite. This mineral is one of the first to crystallise in the cooling of magma and in some cases, incorporates inclusions. Zircon is found in metamorphic rocks like gneisses and schist. Owing to the rare occurrence in the primary rocks, zircon has economic relevance in sedimentary deposits (mineral sands), where it appears with ilmenite, rutile, staurolite, monazite and other high density. 1–4 Mineral sands’ deposits are common in the seacoast in many countries. Australia concentrates the biggest reserves and it is at the same time the world’s largest producer and exporter of zircon concentrate. In 2001, Brazilian reserves were equal to 3?4% of the world’s and the amount produced in the country (21 thousand tons) represented 2?2% of the world’s production. Millennium Inorganic Chemicals do Brasil S/A produced around 11 thousand tons, exclusively destined to the domestic market. 5 In the majority of the producing countries, the more interesting deposits from the economical point of view are unconsolidated or partially consolidated placers. The processing of the run of mine (ROM) ore removes quartz and other light minerals. In the size classification, Reichert cones, spirals or other hydraulic classification devices are used. In some deposits, a step of attrition is necessary for the removal of possible adherent sub- stances from the minerals. After the drying, electrostatic and magnetic separators are employed to generate concentrates of various heavy minerals, such as ilmenite, rutile, zircon and others. 2,4 The relevance of zircon as a raw material is related to its chemical and physical properties, such as high hardness and refraction index, melting point above 1800uC and others. 2,3 These features favour the zircon’s utilisation as a raw material in different industrial sectors, and the main applications are in ceramic products, melting and refractories. In Brazil, the average cost of a superior quality zircon concentrate is about $290. In the international market, the same product costs $350/ton. 5 In the zircon crystal lattice, a process known as metamictisation occurs, which consists on the replace- ment of Zr by other chemical elements. Smith et al. 6 verified that the zircon’s structure can accommodate external ions in the process and in some grains, the authors found that 40% of all Zr content was replaced by Y, Th, Nb, U and Ca cations, among others, and that a low amount of silicon was replaced by aluminium and phosphorus. Gorz and White 7 showed that the iron enters the crystal lattice replacing silicon, and that its concentration can vary between 400 and 15000 ppm. Hartmann et al., 8 in a study with metamictic zircons from the Cac ¸apava granite, in Southern Brazil, identified chemical exchanges between the zircon and the meta- morphic environment, and found that the metamictised portions were strongly enriched in Fe (6100) and in other elements. The Millennium Company’s deposit, known as Guaju Mine, is located in the municipality of Mataraca, in Paraı ´ba State, NE Brazil. The main mineral good 1 Centro Universitario La Salle (Unilasalle), Porto Alegre, Brazil 2 RWTH-Aachen, Lehr- und Forschungsgebiet Aufbereitung mineralischer Rohstoffe, Germany 3 Universidade Federal do Rio Grande do Sul, Mineral Processing Laboratory, Porto Alegre, Brazil *Corresponding author, email irineu.brum@ufrgs.br ß 2009 Institute of Materials, Minerals and Mining and The AusIMM Published by Maney on behalf of the Institute and The AusIMM Received 19 November 2007; accepted 16 February 2009 114 DOI 10.1179/174328509X408270 Mineral Processing and Extractive Metallurgy (Trans. Inst. Min. Metall. C) 2009 VOL 118 NO 2