Beneficiation of low grade Ghorabi iron ore, Bahariya Oasis, Egypt: a case study

摘要

The Ghorabi iron ore is composed mainly of goethite, hematite and quartz minerals. Chemically, four-fifths of the ore (80.65 percent) are iron oxides (44.10 percent, 34.30 percent Fe) and silica (36.81 percent). The size distribution of the ore indicates that iron is concentrated in the fine fraction (>38 percent in fraction -53 mu m) while silica is concentrated in the coarse fraction (>40 percent in fraction +53 mu m). Conditioning of the ore with sodium silicate increases the iron and therefore reduces the silica in the fine fraction (-53 mu m), and attritioning increases the fines (-53 mu m) from 24 to 40.78 percent and iron from 38.64 to 46.20 percent in the fine fraction. In the present study the ore beneficiation is conducted by screening, attritioning, classification and magnetic separation. In the flowsheet, the optimised conditions are considered. The flowsheet includes crushing, grinding, attritioning with sodium silicate and screening into two size fractions, coarse -250 + 53 mu m and fine -53 mu m. The coarse fraction (+ 53 mu m) is subjected to dry, low intensity magnetic separation, while the fine fraction is passed to a hydrocyclone. The overflow is rich in iron but the underflow is subjected to wet, high intensity magnetic separation. The final concentrate is represented by the magnetic fractions in addition to the hydrocyclone overflow, while the tail is represented by the nonmagnetic fractions. The obtained concentrate is of high grade (53.22 percentFe) and good recovery (83.00 percent) and suitable for blast furnace.