The Use of Combustion Reactions for Processing Mineral Raw Materials: Metallothermy and Self-propagating High-temperatur
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I.
INTRODUCTION
THE
methods of metallothermy, MT,[1,2] and self-propagating high-temperature synthesis, SHS,[3,4] are widely used in various branches of science and technology[5–7] to produce metallic and nonmetallic materials.[8–10] They are most widespread in metallurgy,[11,12] chemistry,[13–15] materials science,[16,17] processing of geo- and technogenic materials,[18–34] ecology and economy,[35–43] and other aspects.[44–52] MT and SHS form the basis of pyrotechnics and thermite processes.[53–55] In thermite mixtures, the reductants of solid substances are lithium, sodium, and hydrogen from the elements of the I-st group;[56–61] magnesium and calcium from the II-nd group;[62,63] boron and aluminum from the III-rd group;[64,65] carbon and silicon from the IV-th group,[66,67] and its combination;[68] see also for Al-C, Al-Ca, Al-Mg, Al-Si, Mg-C, and Mg-Zn.[69–74] The other elements, for example, lanthanum and iron, are rarely used.[75–77] The alloys, such as silumin, CaSi, AlSiFe, and AlCaFe;[78–80] gasses, such as nitrogen, oxygen, and water;[81–84] and compounds and elements with intermediate valence, such as aluminum subhalides and suboxides, sulfur, FeO, and SnO are promising.[85–90] At present, various aspects of the traditional thermite processes are rather well investigated. Their advantages and shortcomings are due to very high temperature of
FARIT KH. URAKAEV, Leader Research Associate, Chief of the group, is with the V.S. Sobolev Institute of Geology and Mineralogy of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia. Contact e-mail: [email protected] KENZHEBEK A. AKMALAEV, Professor, and ELJAN S. ORYNBEKOV, Assistant Professor, are with the Kazakh National Technical University after K.I. Satpaev, Almaty, Kazakhstan. BEYKUT D. BALGYSHEVA, Assistant Professor, and DINAR N. ZHARLYKASIMOVA, Ph.D. student, are with the al-Farabi Kazakh National University, Almaty, Kazakhstan. Manuscript submitted November 5, 2014. METALLURGICAL AND MATERIALS TRANSACTIONS B
the combustion front up to 5000 K (4727 C).[91] As a result, the target products are formed as metal beads, sponges, or agglomerates. As a rule, their further investigation requires additional dispersing operations: melting with spraying[92–100] and aggregation and grinding.[100–103] As to the proximate analysis of natural samples under in-situ or laboratory conditions, use of the forming slags as abrasives,[104] reclamation of waste (slags, slimes, etc.) of industrial plants,[105–108] production of precious metals and stones,[109] and the possibilities of thermite processes are less studied. The major advantages of thermite processes are connected with their small energy consumption (they proceed due to substantial thermal effect of the reaction) and universal character (they can be performed either under natural conditions in sites where ores and concentrates occur, or in special reactors under vacuum or any gas medium). In addition, there is the possibility to govern the rate of thermite process by changing the ratio of the
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