| Description |
Titanium is often referred to as "wonder metal" due to its superior properties. At present, titanium is predominantly produced through Kroll's process which is complex, expensive, and needs much higher specific energy than the thermodynamic requirement and that restricts titanium's widespread use. Direct reduction of titanium slag (DRTS) is an alternative process to produce titanium from titanium hydride at a lower projected cost and energy expense. In DRTS, a two-step leaching process is used to lower the aluminum, magnesium, and silicon content in titanium to meet the ASTM International (ASTM) specifications. Magnesium was leached in a mildly acidic condition while aluminum, and silicon impurities were leached under alkaline condition. The effect of varying temperature, concentration of acid or alkali, and adding certain additives to the lixiviants have been investigated for aluminum and silicon removal. Leaching at 140°C for 3 h using a solution of 2 M NaOH and 2.5 g/l of sodium gluconate, and a solid-liquid ratio of 1g to 100 ml, produced titanium hydride with the desired aluminum and silicon contents. The effect of varying temperature, concentration of acid, and solid to liquid ratio have been investigated for magnesium removal. Magnesium content in titanium hydride was lowered below specification requirements by leaching with 0.05 M hydrochloric acid at 50°C for 15 min using solid-liquid ratio of 1 g to 400 ml. Another process for separating titanium from dissolved ilmenite using dihydroxybenzene (catechol) as a metal-organic precipitate was demonstrated. Titanium (IV) was chemically bonded with catechol at a pH of 5.5 to form a precipitate containing 98.7% Ti. The results from density functional theory simulations predicted a gap of 2.914 eV between the two frontier orbital lobes (highest occupied molecular orbital and lowest unoccupied molecular orbital) suggesting stability of the metal complex. This precipitate can be reduced in a hydrogen atmosphere to form titanium hydride which again can be dehydrogenated to form titanium. |
