C80 Mineral Processing and Extractive Metallurgy (Trans. Inst. Min. Metall. C) June 2005 Vol. 114 INTRODUCTION The production of various grades of potassium feldspar from pegmatitic ores has been carried out over the years world-wide. 1 It is well known that the product quality and its value depend on K 2 O and colouring mineral contents, namely iron and titanium oxides. Usually, the K 2 O content is improved by separating quartz by employing flotation and/or magnetic separation depending on ore characteristics. Dry magnetic separation by rare-earth permanent magnets is nowadays the cheapest and most widely used method of separating the colouring minerals. 2,3 However, it is not efficient for separation of minerals with very low magnetic susceptibilities like quartz and albite. Luckily, flotation is well suited and allows the separation of all minerals, including orthoclase–albite separation, to increase the K 2 O content of concentrates further. 4 However, only feldspar–quartz flotation technology has been commercially explored and the floatation of orthoclase selectively from albite largely ignored. There are some studies in the literature showing that this can be achieved by using raw table salt (NaCl) as a depressant for sodium feldspar. 5 Hence, it was decided to study if a low-grade pegmatitic ore could be a source of high-grade potassium feldspar. EXPERIMENTAL Materials The samples used in the experimental studies were received from different low-grade pegmatitic ore veins in Demirci Province in the west of Turkey. Thin- section studies indicated that the matrix consisted of feldspar and quartz bearing brownish to black disseminated bands of impurities; orthoclase, albite, quartz and mica minerals were generally coarse grained, ranging between 0·5–20 mm; the grain size of titanite and rutile was relatively fine being 0·02–0·6 mm and they were mostly found in feldspar minerals as inclusions. With regard to adequate liberation fineness, the ore had to be –300 µm. DOI 10.1179/037195505X39085 Production of potassium feldspar concentrate from a low-grade pegmatitic ore in Turkey Ö. Y. Gülsoy, N. M. Can and I. Bayraktar This paper describes the possibility of producing various grade feldspar concentrates by magnetic separation and flotation. A representative sample was obtained from the Manisa–Demirci region. It was composed of 5·94% K 2 O, 3·14% Na 2 O, 0·61% CaO, 0·41% MgO, 0·11% TiO 2 , 0·65% Fe 2 O 3 , 15·7% Al 2 O 3 and 73·08% SiO 2 as deter- mined by the XRF technique. Microscopic studies on thin sections revealed that muscovite, biotite, tourmaline, sphene and rutile were disseminated in various sizes ranging between 20–500 µm in the matrix of orthoclase, albite and quartz, and for an adequate liberation the sample had to be ground to –300 µm. The non-magnetics were a basic mixture of feldspars and quartz with an alkaline content of 5·86% K 2 O and 2·96% Na 2 O, which was raised to 13·44% (9·22% K 2 O + 4·22% Na 2 O) by only feldspar flotation. For further improvement of K 2 O, orthoclase was differentially floated while albite was simultaneously depressed with NaCl. Finally, a high-grade potassium feldspar concentrate was produced composed of 12·65% K 2 O, 3·1% Na 2 O, 0·11% Fe 2 O 3 , and 0·04% TiO 2 with a glossy white firing button at 1200°C. Ö. Y. Gülsoy (for correspondence – E-mail: ogulsoy@ hacettepe.edu.tr) and N. M. Can (E-mail: metin.can@ hacettepe.edu.tr) are in the Mining Engineering Department, Hacettepe University, Beytepe Ankara, Turkey; and I. Bayraktar is at Çine Akmaden Madencilik Tic. A.S., Aydin- Karpuzlu Karayolu 33. km, 09500 Çine/Aydin, Turkey (E- mail: cineakmaden@cineakmaden.com.tr). © 2005 Institute of Materials, Minerals and Mining and Australasian Institute of Mining and Metallurgy. Published by Maney on behalf of the Institutes. Manuscript received 23 October 2004; accepted in final form 4 March 2005. Keywords: Feldspar concentrate, magnetic separation, flotation, pegmatitic ore Table 1 The feed assay and the source of compounds of the samples Compounds Assay (%) Main source SiO 2 73·08 Quartz and feldspars Al 2 O 3 15·70 Feldspar, micas Fe 2 O 3 0·54 Tourmaline, biotite, some stains of iron oxides TiO 2 0·09 Titanite, rutile, biotite and muscovite MgO 0·41 Biotite CaO 0·61 Plagioclase K 2 O 5·94 Orthoclase, micas Na 2 O 3·14 Albite, tourmaline LOI 0·49