Saint Petersburg, Russia
Saint Petersburg, Russia

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Domanskiy I.V.,Engineering and Technical Center | Davydov I.V.,Engineering and Technical Center | Borovinskiy V.P.,Engineering and Technical Center | Malofeev M.N.,Engineering and Technical Center | Morozov A.A.,Engineering and Technical Center
Tsvetnye Metally | Year: 2014

The diaspore and diaspore-boehmite bauxite digestion in Bayer circuit is conducted under relatively high temperature (230- 260 °C), using continuous digesters. As a rule, the multistage (8-10 stages) flashing of hot slurry (230-260 °C) is provided in the flowsheets of modern digestion trains in order to reduce the temperature up to 102-105 °C before further processing. The generated secondary steam is selected from each flash tank and is used for indirect heating of raw bauxite slurry, which is delivered to leaching by the process, using counter-current circuit. The special narrow devices (orifices) are installed on the cross-flow pipes, connecting the flash tanks for staged slurry cooling in each flash tank and generation of secondary steam with required parameters. These devices are installed with the aim to shut the free movement of slurry from cross flow pipe into appropriate flash tank. For calculation of the orifice hole diameter, the value of discharge flow ratio should be known for this steam-liquid mixture. This paper presents the results of study for water-steam and system appropriate for alumina production "aluminate liquor - steam". It was experimentally proven that with the flow of overheated water through the orifice, the efflux factor is the same, as far as evaporation occurs only from the surface of the flowing liquid jet. The suggestion, that evaporation of liquid from steamliquid mixture occurs only from the surface of dispersed liquid, made it possible to define the ratio, specifying the share of dispersed liquid (k) in the model of incomplete mixing. The industrial and calculated data are given in the study.

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