Thermal treatment for separating quartz from geethitic iron ore of Gebel Ghorabi, Bahariya oasis, Western Desert, Egypt

Gebel Ghorabi is located at the extreme northern end of Bahariya Oasis and the mineralized area covers an area of about 2 km². Geologically, the iron ore is composed of random alternations of three main yellow, brown and dark brown colored bands. The former band is relatively thicker than the others. The iron particles range in size from a (pisolitic ⪢) fraction > 2 mm to earthy (the so-called pisolites may grade down from coarse to about 0.25 mm in size).

A bulk sample corresponding more or less to the yellow iron ore band contains 54.16% Fe₂O₃, 26.13% SiO₂ and 5.39% Al₂O₃ as major components.

Technologically, the combined effect of a thermal reduction and of a quenching shock on the crushed iron sample (-12 mm) has been investigated. This technique has been found to sufficiently enhance the magnetic properties of the iron minerals which could be easily separated by using a low intensity magnetic separator.

The maximum severance of quartz grains from the reduced iron oxides was reached for samples subjected to a slow heating at 700°C for 60 min. and to a fast cooling by quenching in water.

A flow sheet for handling the yellow iron ore is here proposed to produce a magnetic iron concentrate with 87.63% Fe₃O₃ and 1.40% SiO₂, and with a recovery of 97.21%.