National University of Science and Technolgy – NUST MISIS, Moscow, Russia:

Yushina T. I., Head of Department, Associate Professor, Candidate of Engineering Sciences, yuti62@mail.ru
Nguyen Thu Thuy, Post-Graduate Student
Dumov А. М., Associate Professor, Candidate of Engineering Sciences
Nguyen Van Trong, Probationer

Feldspar is the largest group of aluminosilicate minerals making around 50% of the lithosphere mass. Feldspar is a high-value raw materials used in various industries in production of glass, ceramics, electrical insulators, abrasives, as well as an aggregate in production of plastics, paints, rubber, etc. A major source of high-grade feldspar is granitic pegmatites. The Social Republic of Vietnam possesses considerable feldspar reserves but mostly in weathered and semi-weathered pegmatite zones, which governs the complex material constitution of feldspar material and the diverse lattice architecture of feldspar weathering products. The article describes the integrated studies into the material constitution of quartz–feldspar ore from Quang Nam deposit in Vietnam. It is found that the ore has a rather complex composition. Alongside with the base useful component – feldspar represented by orthoclase and albite, the ore contains free quartz, mica group minerals (muscovite) and iron-bearing minerals as inclusions and coats in feldspar. The iron mineral coats are observed on the surface of muscovite grains. The mass percentage of Al₂O₃ is on average 14.20%; Fe₂O₃ – 0.75%; SiO₂ – 75.27%. The total percentage of alkali metal oxides (K₂O+Na₂O) is similar in different size grades and makes on average 8.64%. The yield and distribution of useful component y size grades are relatively uniform. The analysis of the research findings allows drawing the conclusion that most efficient method to remove impurities of mafic minerals, including iron minerals, and free quartz is flotation. The feldspar ore flotation flow chart should include four stages: desliming (removal of clayey minerals); flotation of mina group minerals; flotation of iron-bearing minerals; flotation of feldspar. The proposed ore pretreatment circuit with selective milling and desliming enables production of mica concentrate with the size of +2 mm. The studies into material constitution of Quang Nam quartz–feldspar ore prove that this ore is processable toward production of valued products in high demand in many industries.

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