Mineralogy, Chemical Characteristics and Upgrading of Beach Ilmenite of the Top Meter of Black Sand Deposits of the Kafr Al‐Sheikh Governorate, Northern Egypt

Abstract

Egyptian beach ilmenite occurs in a relatively high content in the naturally highly concentrated superficial black sand deposits at specific beach zones in the northern parts of the Nile Delta at Rosetta. Microscopic study shows that the ilmenite occurs as fresh homogeneous black or heterogeneous multicoloured altered grains and exhibits three types (homogeneous, exsolved and altered) of ilmenite varieties. XRD data of ilmenite indicates their association with minor hematite and quartz, whereas leucoxene shows its association with Nb‐rutile, pseudorutile and hematite. Grain size distribution suggests a very fine sand size of >89% and 80% and a fine sand size of 10.5% and 18.3% for fresh and altered ilmenites, respectively. The density of fresh, altered ilmenite and leucoxene concentrates varies from 2.70, 2.50 to 2.40 ton/m3, suggesting a gradual decrease from high grade fresh to leucoxene and consistent with variation in magnetic susceptibility as a consequence of the leaching of iron. Mass magnetic susceptibility reveals 97.6% of ilmenite and 92% of the altered form are obtained at 0.20 and 0.48 ampere. Fresh ilmenite exhibits variable TiO2 (47.18%) and Fe2O3T (46.10%) with minor MnO, MgO and Cr2O3 (1.22, 1.10 and 0.51%). The altered ilmenite is higher in TiO2 (76.16%) and SiO2 (4.68%) and lower in Fe2O3T (14.45%), MnO, MgO and Cr2O3 (0.39, 0.52 and 0.11%) compared with the fresh form. Three concentrates of ilmenites (G1, G2 and G3) were prepared from crude ore using a Reading cross belt magnetic separator under different conditions, revealing a gradual increase of TiO2, SiO2, Al2O3 and CaO accompanied by a decrease of Fe2O3T, MgO and Cr2O3 with repetition of the separation processes. Several ore dressing techniques were carried out to upgrade the ilmenite concentrate.

Global distribution, genesis, exploitation, applications, production, and demand of industrial heavy minerals

“…Leucoxene or altered ilmenite (referred to as a mixture of pseudorutile and rutile) is also a source of titanium (Frost et al 1983 ). The colour of leucoxene is variable, from black, dark brown, light brown, light grey, reddish, orange, and yellow, through to white (Abdel-Karim et al 2017 ). However, the inherent colour (commonly yellow or white) of leucoxene depends on the degree of alteration and TiO 2 content with little or no Fe (Temple 1966 ).…”

“…The process of ilmenite alteration is known as leucoxinisation (Abdel-Karim et al 2017 ), the degree of which increases the impurity levels by increasing SiO 2 and Al 2 O 3 contents (Hugo and Cornell 1991 ). The name “leucoxene” is used for the end product of the alteration process.…”

“…Zircon is extremely resistant to weathering and abrasion, and hence is common in sedimentary rocks and in alluvial and beach placer deposits (Dryden and Dryden 1946 ; Armstrong-Altrin et al 2015 ). Zircon occurs in a range of colours, such as colourless, red, brown, yellow, grey, pink, and green (Abdel-Karim et al 2017 ). Hafnium (Hf) and zirconium (Zr) are geochemically similar, and Hf can replace Zr in the zircon crystal lattice (Abdel-Karim et al 2017 ).…”

“…Zircon occurs in a range of colours, such as colourless, red, brown, yellow, grey, pink, and green (Abdel-Karim et al 2017 ). Hafnium (Hf) and zirconium (Zr) are geochemically similar, and Hf can replace Zr in the zircon crystal lattice (Abdel-Karim et al 2017 ). The amounts of Hf, Y, Nb, and Ta within the crystal lattice vary between zircon species.…”

“…The amounts of Hf, Y, Nb, and Ta within the crystal lattice vary between zircon species. Zircons with higher Hf contents and those with higher Y, Nb, and Ta are called alvites and naegites, respectively (Abdel-Karim et al 2017 ). Zircon is also considered to be a gemstone (Jain et al 2001 ; Dill 2010 ).…”