Application of the radioisotope excited X-ray fluorescence technique in charge optimization during thermite smelting of

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Communications Ar outlet/Manometer,

Application of the Radioisotope Excited X-Ray Fluorescence Technique in Charge Optimization during Thermite Smelting of Fe-Ni, Fe-Cr, and Fe-Ti Alloys

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I.G. SHARMA, Scientific Officer, and D.K. BOSE, Head, High Temperature Materials Section, Metallurgy Division, and D. JOSEPH and MADAN LAL, Scientific Officers, Nuclear Physics Division, are with the Bhabha Atomic Research Centre, Trombay, Bombay 400085, India. Manuscript submitted July 25, 1994. METALLURGICALAND MATERIALSTRANSACTIONS B

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I.G. SHARMA, D. JOSEPH, MADAN LAL, and D.K. BOSE A wide range of ferroalloys are used to facilitate the addition of different alloying elements to molten steel.[ II Highcarbon ferroalloys are produced on a tonnage basis by carbothermic smelting in an electric fi~mace, and an aluminothermic route is generally adopted for small scale production of low-carbon varieties. The physicochemical principles of carbothermym and aluminothermy[2] have been well documented in the literature. However, limited technical data are reported on the production of individual ferroalloys of low-carbon varietiest3] from their selected resources. We demonstrate here the application of an energy dispersive X-ray fluorescence (EDXRF) technique in meeting the analytical requirements of a thermite smelting campaign, carried out with the aim of preparing low-carbon-low-nitrogen Fe-Ni, Fe-Cr, and Fe-Ti alloys from indigenously available nickel bearing spent catalyst, mineral chromite, and ilmenite/rutile, respectively. We have chosen the EDXRF technique to meet the analytical requirements because of its capability to analyze samples of ore, minerals,[41 metal, and alloys in different forms, such as powder, sponge, as-smelted, or as-cast, to obtain rapid multielement analyses with ease. Rapid analyses of thermite feed and product by this technique have aided in the appropriate alterations of the charge constituents to obtain optimum charge composition. Alloy smelting experiments were conducted in a oneend-closed water-cooled copper reactor shown schematically in Figure 1. This kind of specially designed copper reactor was chosen instead of a conventionally used refractory lined reactor to prevent contamination of the product from the refractory lining and to avoid regular maintenance, as well as relining, of the reactor. The inside portion of the reactor was slightly tapered to facilitate the collection of alloy. All the constituents of thermite charge except reductant aluminum were appropriately heated to ensure complete removal of moisture. This stage is essential from the point of view of the safety of operation and the success of the smelting campaign. The reactants consisting of Fe203, heat booster KC103, aluminum powder, and an appropriate source of primary metal (spent catalyst/chromite/ilmenite or rutile) were intimately mixed, poured inside the reactor cavity, and rammed gently. The unit wa