Ceramics-Silikáty 54 (1) 60-64 (2010)

SELECTIVE SEPARATION OF Na- AND K-FELDSPAR FROM WEATHERED GRANITES BY FLOTATION IN HF MEDIUM

C. Demir

Granite and granodiorite deposits are widely scattered throughout in Eastern Black Sea region of Turkey. These granitic bodies also contain considerable amounts of quartz, Na-feldspar, K-feldspar, mica and other color-imparting ferruginous impurities. Average chemical composition of these rocks are SiO₂ = 65.00 ±5.60; K₂O = 3.05 ±1.35; Na₂O = 3.50 ±1.47 %. Modally, these rocks contain 21.5 ±5.2 quartz; 19.3 ±4.8 K-feldspar and 48.3 ±10.2 % plagioclase. Although the chemical composition of these run-of-mine granite masses cannot meet the specifications required for the glass and ceramic industry, application of some mineral processing methods may recover quartz, Na-feldspar and K-feldspar as separate products. This study deals with the selective separation of sodium feldspar from potassium feldspar from weathered granite using cationic flotation technique (HF + amine) in the presence of NaCl. The most striking result in this experimental study is the depressive effect of NaCl on Na-feldspar. NaCl addition controls amine adsorption on sodium feldspar through adsorption of Na⁺ ions onto mineral surfaces. The use of NaCl in flotation was found to increase the K-feldspar grade in the concentrate. This study clearly demonstrates that an effective separation of sodium feldspar from potassium feldspar from a weathered granite can be achieved by cationic flotation in HF medium using NaCl as a depressant.

Keywords: Feldspar, Selective separation, Weathered granites, Flotation, Monovalent salts