MODELING THE TAPPING OF SILICON MELT FROM THE SUBMERGED ARC.pdfVIP

Seventh International Conference on CFD in the Minerals and Process Industries CSIRO, Melbourne, Australia 9-11 December 2009 Copyright ? 2009 CSIRO Australia 1 MODELING THE TAPPING OF SILICON MELT FROM THE SUBMERGED ARC FURNACES Mehdi KADKHODABEIGI1 , Halvard TVEIT1 and Stein Tore JOHANSEN2 1Department of Materials Science and Engineering, Norwegian University of Science and Technology (NTNU), PO Box7491, Trondheim, NORWAY 2SINTEF Material and Chemistry, Flow technology group, PO Box 7465, Trondheim, NORWAY ABSTRACT In this paper we investigate flow phenomena related to tapping of silicon melt from a submerged arc furnace. The multiphase flow model predicts how the gas pressure variations inside the furnace crater zone may effect phenomena like the gas flow pattern inside different zones of the charge materials inside the furnace, the metal tapping flow rate, and the gas blow out from the furnace tap hole. The full 3D multiphase flow model of the furnace is based on the real geometry and the most probable physical properties of different zones in the furnace, such as density, charge material particles size, porosity and permeability of the packed beds on the furnace bottom. In addition different spatial arrangements of charge material zones have been investigated. The results of the model show that existence of the mentioned high pressure crater zone in the furnace has a considerable effect on the metal tapping and the gas flow rate from the tap hole. The predicted tapping rate compares well to industrial tapping trials, using crater pressure levels that has been measured previously on a ferrosilicon furnace. The model also shows that gas blow out from the tap hole can change the gas flow pattern inside the charge materials all the way to the furnace top. NOMENCLATURE kρ density of phase k kvr velocity of phase k ε void fraction (porosity) g gravity acceleration kμ viscosity of phase k L depth