This paper aims to beneficiation of Um Gheig nonsulfide Zinc ore from
its associated gangues using the gravity separation “shaking table"
technique. The different operating parameters affecting of the efficiency
of the separation process is evaluated.
The zinc locality of Um Gheig represents one of the important nonsulfide
zinc deposits along the coastal plain of the Red Sea Coast, Egypt. These
zinc ores are called “calamines" and consist mainly of a mixture of zinc
carbonates (smithsonite, hydrozincite) and zinc silicates (hemimorphite),
with a variable content of calcite, goethite and Pb bearing minerals.
Extensive mineralogical (using XRD, XRF) and petrographic studies
have been carried out on the selected samples from Um Gheig Mine.
Theses investigations show that, the nonsulfides mineral association in
the deposit consists mainly of smithsonite (50.74%), hydrozincite
(18.78%) and hemimorphite (14.78%) replacing both primary ore
minerals and carbonate host rocks. Smithsonite occurs in two
generations, cryptocrystalline mixed with goethite and rhombohedral
crystals, precipitate in vugs and open space of the high grade ore. The
main gangue minerals are calcite and goethite. XRF analysis indicates
that the sample contains 47.50% ZnO, 1.55% PbO and about 29.28%
L.O.I.
Liberation and mineralogical investigation showed that higher degree of
liberation (over 90%) between the valuable zinc bearing minerals and
their gangues can be achieved below the size 0.106 mm.
The results of gravity separation showed that the best operating
parameters to obtain a concentrate with high assay and recovery are at
inclination angle (4 degree), stroke length (2.5 cm), feed rate (150 gm /
min), and water flow rate (25 l / min). At these optimum conditions a
concentrate assaying 60.85 % ZnO was obtained with a recovery of
~90 %.