Chair of Non-Ferrous Metals and Gold, National University of Science and Technology “MISiS”, Moscow, Russia:

A. S. Medvedev, Professor, e-mail: vimideev@gmail.com
S. S. Kirov, Assistant Professor
R. T. Khayrullina, Assistant Professor

LLC “RUSAL Engineering-Technological Center”, Saint Petersburg, Russia:
A. G. Suss, Director of Technological Department of Engineering and Technological Direction of Aluminous Production

This article considers the aspects of preliminary waste gassing of red mud pulp sintering furnaces, intended for scandium extraction from slime by carbonatebicarbonate leaching. The chosen preliminary gassing conditions are substantiated. There are shown the data of alkali redistribution between liquid and solid phases with increasing the gassing time and dynamics of pH changes of liquid phase under carbonic acid and air-gas mixture passing through it. The degree of CO₂ assimilation by solution from air-gas mixture is calculated. There are no significant changes in the slime phase composition during the carbonic acid gassing and carbonatebicarbonate leaching. The effect of spontaneous pH pulp increasing occurs on gassing termination, and carbonic acid is involved not only in the alkali neutralization but also in the reaction of sodium bicarbonate formation needed for complexing in scandium leaching process. There are shown the data demonstrating the possibility of the carbonatebicarbonate leaching of scandium-containing slime with the solution containing 20 g/dm³ of carbonate and 40 g/dm³ of bicarbonate without the preliminary gassing of slime pulp with carbonic acid. The furnace waste gases (bauxite with soda and limestone sintering, alumina calcination and lime calcination) may be industrially applied as a source of carbonic acid. The influence of waste gas dust of the sintering furnaces on gassing efficiency is considered (in particular, the degree of alkali transition from dust to the solution).
This article is written with the subsidiary agreement No. 14/578.21.0014 (June 05, 2014) (unique identifier : RFMEFI57814X0014) between the National University of Science and Technology “MISiS” and the Ministry of Education and Science of Russian Federation, within the realization of the Federal Target Program “Investigations and developments in the priority ways of development of scientific-technological complex of Russia for the period of 2014-2020”, approved by the governmental regulation of Russian Federation (November 28, 2013, No. 1096.)

1. Yatsenko S. I., Sabirzyanov N. A., Pasechnik L. A. Pererabotka boksitovogo shlama s polucheniem glinozemistogo i redkometalnogo kontsentratov, skandievoy soli i ligatury (Bauxite slime processing with obtaining the aluminous and rare-metal concentrates, scandium salt and ligature). Khimicheskaya tekhnologiya = Theoretical Foundations of Chemical Engineering. 2004. No. 12. pp. 28–34.
2. Sabirzyanov N. A., Yatsenko S. P., Pasechnik L. A. Tekhnologiya kompleksnoy pererabotki boksitovogo shlama (Technology of complex processing of bauxite slime). Metallurgiya legkikh metallov. Problemy i perspektivy : sbornik trudov nauchno-prakticheskoy konferentsii (Metallurgy of light metals. Problems and prospects : collection of proceedings of scientific-practical conference). Moscow, 2006. pp. 179–181.
3. Liu D. Y., Wu C. S. Stockpiling and Comprehensive Utilization of Red Mud Research Progress. Materials. 2012. No. 5. pp. 1232–1246.
4. Raghavan P. K. N. Recovery of metal values from red mud. Light metals. 2011. pp. 23–26.
5. Nikolaev I. V., Zakharova V. I., Khayrullina R. T. Kislotnye sposoby pererabotki krasnykh shlamov. Problemy i perspektivy (Acidic methods of processing of red muds. Problems and prospects). Izvestiya vuzov. Tsvetnaya metallurgiya = Russian Journal of Non-Ferrous Metals. 2000. No. 2. pp. 19–26.
6. Besedin A. A. Gidrokhimicheskaya uglekislotnaya obrabotka krasnogo shlama glinozemnogo proizvodstva (Hydrochemical carbonic-acid processing of aluminous production red mud). Estestvennye i tekhnicheskie nauki = Natural and technical sciences. 2014. No. 1. pp. 268–272.
7. Deelwal K. Evaluation of characteristic properties of red mud for possible use as a geotechnical material in civil construction. International Journal of Advances in Engineering & Technology. 2014. July, Vol. 7, No. 3. pp. 1053–1059.
8. Qiu X. R., Qi Y. Y. Reasonable utilization of red mud in the cement industry (In Chinese). Cemical Technology. 2011. No. 6. pp. 103–105.
9. Pyagay I. N., Yatsenko S. P., Pasechnik L. A. et al. Sposob polucheniya oksida skandiya iz krasnogo shlama (Method of scandium oxide obtaining from red mud). Patent RF, No. 2483131, IPC C 22 B 59/00, C 22 B 3/04, C 22 B 3/20, C 01 F 17/00. No. 2011153456/02. Applied : December 26, 2011. Published : May 27, 2013.
10. Orlov S. L., Entelis I. Yu., Smirnov B. N. Sposob izvlecheniya redkozemelnykh metallov skandiya i ittriya iz krasnykh shlamov glinozemnogo proizvodstva (Method of extraction of rare-earth scandium and yttrium metals from aluminous production red muds). Patent RF, No. 2147622, IPC C 22 B 59/00, C 22 B 7/00, B 03 C 1/00. No. 99120765/02. Applied : October 06, 1999. Published : April 20, 2000.
11. Medvedev A. S., Khayrullina R. T., Kirov S. S., Suss A. G. Poluchenie tekhnicheskogo oksida skandiya iz krasnogo shlama Uralskogo alyuminievogo zavoda (Technical scandium oxide obtaining from red mud of Urals Alumi nium Smelter). Tsvetnye Metally = Non-ferrous metals. 2015. No. 12. pp. 47–52. DOI: http://dx.doi.org/10.17580/tsm.2015.12.08
12. Pasechnik L. A. Kompleksoobrazuyushchaya sposobnost skandiya (III) v shchelochnoy srede (Complexing ability of scandium (III) in alkaline medium). Zhurnal prikladnoy khimii = Russian Journal of Applied Chemistry. 2004. Vol. 7, Iss. 7. pp. 1086–1089.
13. Rudolph W. W. Raman spectroscopic studies of Scandium (III) hydration in aqueous solution about the Fist Hydration Sphere of Sc (III) in Solution. Zeitschrift für Physikalische Chemie (Muenchen). 2000. Bd. 214 (2). pp 221–238.