TRANSACTION PAPER

Leachability of nitrided ilmenite in hydrochloric acid

J.J. Swanepoel^I; D.S. van Vuuren^I; M. Heydenrych^II

^IMaterials Science and Manufacturing, CSIR
^IIDepartment of Chemical Engineering, University of Pretoria

SYNOPSIS

Titanium nitride in upgraded nitrided ilmenite (bulk of iron removed) can selectively be chlorinated to produce titanium tetrachloride. Except for iron, most other components present during this low temperature (ca. 200°C) chlorination reaction will not react with chlorine. It is therefore necessary to remove as much iron as possible from the nitrided ilmenite. Hydrochloric acid leaching is a possible process route to remove metallic iron from nitrided ilmenite without excessive dissolution of species like titanium nitride and calcium oxide. Calcium oxide dissolution results in unrecoverable acid consumption. The leachability of nitrided ilmenite in hydrochloric acid was evaluated by determining the dissolution of species like aluminium, calcium, titanium and magnesium in a batch leach reactor for 60 minutes at 90°C under reflux conditions. The hydrochloric acid concentration (11%, 18% and 25%), initial acid-to-iron mole ratio (2:1, 2.5:1 and 3.3:1), and solid-to-liquid mass ratio (1:8.33 to 1:2.13) were varied. The results indicate that a hydrochloric acid concentration of 25 wt% supplied in a 2:1 acid-to-iron mole ratio would produce the most favourable upgraded nitrided ilmenite product. The dissolution of iron in this solution reached 97 per cent after only 60 minutes. The total dissolution of calcium and titanium species was 0.01 and 0.11 wt% respectively. Hydrochloric acid can therefore be used as lixiviant to remove metallic iron from nitrided ilmenite.

Keywords: Titanium nitride, upgraded nitrided ilmenite, hydrochloric acid leaching, metallic iron dissolution

“Full text available only in PDF format”

References

1. MOSTERT, G.J. et al. Process for the recovery of titanium values. U.S. Pat 5,224,986: 6 July 1993.         [ Links ]

2. VAN VUUREN, D.S. and STONE, A.K. Selective recovery of titanium dioxide from low grade sources, South African Chemical Engineering Congress, 20-22 September 2006, Durban.         [ Links ]

3. LANYON, M.R., LWIN, T., and MERRITT, R.R. The dissolution of iron in the hydrochloric acid leach of an ilmenite concentrate. Hydrometallurgy, vol. 51, no. 3, 1999, pp. 299-323.         [ Links ]

4. WALPOLE, E.A. and WINTER, J.D. The Austpac ERMS and EARS Processes for the Manufacture of High-Grade Synthetic Rutile by the Hydrochloric Acid Leaching of Ilmenite, Chloride Metallurgy 2002-International Conference on the Practice and Theory of Chloride/Metal interaction, October 2002, Montreal.         [ Links ]

5. WANG, Z., XUE, J., WANG, H., and JIANG, X. Kinetic study of hydrochloric acid leaching process of ilmenite for rutile synthesis, EPD Congress 2009, The Minerals, Metals & Materials Society, 2009, pp. 837-843.         [ Links ]

6. WINTER, J. Production of Synthetic Rutile by Continuous Leaching. U.S. Pat 7,404,937: 29 July 2008.         [ Links ]

7. EL-HAZEK, N., LASHEEN, T.A., EL-SHEIKH, R., and ZAKI, S.A. Hydrometallurgical criteria for TiO2 leaching from Rosetta ilmenite by hydrochloric acid. Hydrometallurgy, vol. 87, 2007, pp. 45-50.         [ Links ]

8. VAN DYK, J.P., VEGTER, N.M., and PISTORIUS, P.C. Kinetics of ilmenite dissolution in hydrochloric acid. Hydrometallurgy, vol. 65, 2002, pp. 31-36.         [ Links ]

9. MAHMOUD, M.H.H., AFIFI, A.A.I., and IBRAHIM, I.A. Reductive leaching of ilmenite ore in hydrochloric acid for preparation of synthetic rutile. Hydrometallurgy, vol. 73, no.s 1-2, 2004, pp. 99-109.         [ Links ]

10. PISTORIUS, P.C. Ilmenite smelting: The basics. The Journal of Southern African Institute of Mining and Metallurgy, vol. 108, 2008, pp. 35-43.         [ Links ]