A study on carbothermic reduction of ilmenite ore in a plasma reactor
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I.
INTRODUCTION
IN recent years, research on composite materials has gained considerable momentum, and a process for producing cast aluminum metal-matrix composites has already been commercialized.[1] The TiC-reinforced ferrous composites are drawing the attention of researchers for their application as wear-resistant components, tools, dies, oxidation, and corrosion-resistant components. The literature on production of TiC-reinforced ferrous composites[2–6] indicates that, generally, TiC is introduced in a ferrous matrix either through the powder metallurgy (PM) route or through direct precipitation from the melt of an appropriate alloy.[2,7,8] One research group, however, has reported trials on direct carbothermic reduction of ilmenite in a levitation melting furnace to produce small quantities of a composite.[9] The liquid route for producing composites that provides the opportunity for direct casting of components into different shapes offers advantages over the PM route. In the present investigation, an attempt has been made to produce TiC-reinforced composites by carbothermic reduction of ilmenite ore in a plasma furnace. A 35 kW direct current (DC) transferred arc plasma reactor was specially designed and fabricated for this purpose. The reactor has been used to study the effects of various variables on the recovery of titanium and iron values from ilmenite. II.
EXPERIMENTAL
Section A gives a brief description of the plasma reactor used for ilmenite smelting. It is similar to the reactor described in an earlier publication[10] from the laboratory. A. 35 kW dc Extended Arc Plasma Reactor A schematic sketch of the extended arc plasma reactor is shown in Figure 1. It is a pot reactor where a magnesialined graphite crucible serves as the reactor hearth. The crucible is thermally insulated by bubble alumina in a mild steel casing. The hearth is provided with a tap hole, and a
R.K. GALGALI, Deputy Director, and H.S. RAY, Director, are with the Regional Research Laboratory, Bhubaneswar-751 013, India. A.K. CHAKRABARTI, Professor, is with the Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur-721 302, India. Manuscript submitted December 10, 1997. METALLURGICAL AND MATERIALS TRANSACTIONS B
graphite spout is connected to it for tapping both metal and slag. Two graphite electrodes are arranged in a vertical configuration in the reactor. The bottom electrode, which is the anode, is fixed, and the arc plasma stabilization is done through the adjustment of the top electrode (cathode) that is actuated by a rack and pinion mechanism. The ends of both the electrodes are water cooled. The cathode has an axial hole for the passage of the plasma-forming gas. A graphite sleeve is provided in the lid with ceramic insulation to promote free travel of the electrode without electrically shorting the body. The lid is thermally insulated by magnesia ramming mass and is furnished with an opening for the exhaust gases. The anode is also introduced into the hearth through a ceramic ins
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