The selective chlorination of iron from llmenite ore by CO-Cl 2 mixtures: Part I. intrinsic kinetics
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= 33.7 exp
- ~-~
pgi~Zpg~322t
where E is 37.2 k J / m o l and p and t are in arm (= 101.3 kPa) and minutes, respectively. The partial pressure of carbon monoxide was found to affect the chlorination rate more strongly than that of chlorine. A reaction mechanism in which iron in ilmenite reacts with chlorine before the liberated oxygen is removed by carbon monoxide is proposed.
I.
INTRODUCTION
T I T A N I U M has found increased use in aerospace and commercial applications, because it has an attractive combination of properties, such as excellent strengthto-weight ratio and high corrosion and erosion resistances, v,zJ Further, the demand for titanium dioxide, which is the most consumed of all the forms of titanium, is quickly growing in the paper and plastics industries, as well as in pigment industries.~3] High purity titanium metal and titanium dioxide are produced from the intermediate titanium tetrachloride which is obtained by the chlorination of a high-grade titanium ore, mainly rutile. However, deposits of futile occur in a limited number of places, such as Australia, Sri Lanka, South Africa, India, and Sierra Leone; t41 we are experiencing a shortage, and it is becoming more expensive to mine. Therefore, other abundant low-grade titanium minerals, such as ilmenite (FeTiO3), arizonite (Fe203"nTiO2.mI-I20), leucoxene (FezO3.nTiO:), perovskite (CaTiO3), and titaniferous magnetite, must be utilized as substitutes for futile. Due to the high content of impurities in these minerals, especially iron, it is necessary to upgrade them to obtain synthetic rutile which is acceptable as a feedstock for chlorination. A number of processes t5-~2] have been proposed for the removal of iron from low-grade titanium ore, such as chlorination by various agents with or without pretreatment, smelting followed by sulfation and hydrochloric acid leaching, hydrogen reduction followed by ferric salt leaching, high temperature/high pressure leaching with sulfuric acid in the presence of a reducing agent, and solid-state reduction followed by chemical or physical separation. K.I. RHEE, formerly Graduate Student at the Department of Metallurgical Engineering, University of Utah, is Head of Rare Metals Research Department, Korea Institute of Energy and Resources, Daejeon, Korea. H.Y. SOHN, Professor, is with the Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84112-1183. Manuscript submitted September I, 1988. METALLURGICAL TRANSACTIONS B
A m o n g these processes, the direct chlorination has a significant advantage in that it can be done with conventional chlorination equipment and requires no pretreatment, such as roasting or slagging. However, some operational difficulties are associated with this process due to the defluidization and clogging caused by high boiling point metal chlorides produced during chlorination. Nonetheless, these difficulties can be removed by the control of temperature, amount of reducing agent, and the partial pressure of chlorine. Usually, direct chlorination can be
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