TITLE:
Differential Flotation of Some Egyptian Feldspars for Separation of Both Silica and Iron Oxides Contaminants
AUTHORS:
Tawfik Refaat Boulos, Suzan Sami Ibrahim, Ahmed Yehia
KEYWORDS:
Na-Feldspar, K-Feldspar, Flotation, Sand Separation, Effect of pH
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.3 No.6,
November
5,
2015
ABSTRACT: An anionic-cationic flotation of two Egyptian feldspar samples, representing Road Ashaab locality
of the Eastern Desert of Egypt, was investigated on both laboratory and pilot plant scales. The
pegmatites belong to the alkali feldspar granite type, mostly microcline and orthoclase, KAL Si3O8
coarse grained rocks. Quartz, as the main gangue mineral, occurs in two forms as either free grains
or as veins intercalating the feldspar crystals or, sometimes, intermingled with them. Iron, on the
other hand, is found in three different forms as free magnetite embedded in the feldspar crystals,
as microcrystalline crystals, or as magnetite filling cracks in the feldspar. Dissolution of magnetite
to hematite is, sometimes, observed. Grinding of the feldspar samples to less than 0.25 mm followed
by desliming was optimized in the laboratory, using a ball mill in closed circuit with the
screen. Anionic flotation of the iron oxide impurity from the -0.25 + 0.03 mm ground product was
successfully conducted using locally produced dodecyl benzene sulphonic acid—rice bran oil/kerosene
promoter at pH 3. Cationic flotation of feldspar from this product was then carried out employing
a locally produced quaternary ammonium salt in presence of HF acid, as a silica depressant
and a feldspar activator at pH 3. Feldspar final concentrates assaying 80.8% - 89.5% feldspar
mineral, 0.119% - 0.127% Fe2O3 and 16.84% - 18.65% Al2O3, were obtained at the optimum operating
conditions that satisfy the requirements of the ceramic industry. Continuous 200 kg/h pilot
plant runs were conducted using the appropriate equipment, based upon the laboratory findings
to produce feldspar concentrates assaying 16.38% - 18.13% Al2O3, and 0.13% - 0.15% Fe2O3. Materials’
metallurgical balance and complete chemical analyses were shown.