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Low-temperature Smelting of Ilmenite in Borate Melts to Produce Pig Iron and Titania-containing Slag.

Gomes-JM; Uchida-K
U S Pat 3 829 309 1974 Aug; :
An ilmenite concentrate, tio2 61 and feo 37 wt pct, is smelted with a sodium borate flux and a carbonaceous reducing agent, such as coal, in a furnace at 1,150 deg to 1,200 deg c to produce a marketable molten pig iron containing 95 to 97 wt pct fe and a slag containing 25 wt pct tio2 and <1 wt pct feo. Ti recovery in the slag is 95 to 99 pct. Two alternative procedures then may be employed to obtain a sodium titanate product containing 70 to 80 wt pct tio2, which can be readily converted to pigment-grade tio2 by the sulfate process. By one procedure, the quenching-leaching method, air or o2 is blown through the molten slag for 5-15 min at 1,000 deg c to oxidize ti3+ to ti4+ and the slag is then poured into water to form granules. The slag granule slurry is then agitated for 2 h at 80 deg to 90 deg c to dissolve residual borates. The granular, noncrystalline sodium titanite is recovered by filtration and drying. Sodium borate is recovered from the leach solution by evaporation and crystallization and returned to the smelting step. By the leaching-calcination option, the slag is first allowed to cool somewhat and is then crushed to minus 35 mesh and leached 2 h at 80 deg to 90 deg c to dissolve borates. This step upgrades the slag from 25 to 70-80 wt pct tio2. Sodium titanate and sodium borate are recovered, as before, by filtration and evaporation, respectively. The upgraded sodium titanate product then is calcined at 300 deg to 400 deg c to oxidize ti3+ to ti4+.
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PAT 3,829,309
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U.S. Pat. 3,829,309, Aug. 13, 1974, Chem. Abstr. Not Found