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Master's Dissertation
DOI
10.11606/D.97.2014.tde-07112014-161607
Document
Author
Full name
José Milton Gabriel Lopes
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Lorena, 2014
Supervisor
Committee
Vernilli Junior, Fernando (President)
Coelho, Gilberto Carvalho
Justus, Sérgio Murilo
Title in Portuguese
Estudo comparativo entre os efeitos da adição de fluorita e sodalita nefelínica nas propriedades da escória do refino primário de aços
Keywords in Portuguese
Escória
Fluorita
Nefelina
Refratários de MgO-C
Sodalita Nefelínica
Abstract in Portuguese
O controle das características da escória de refino primário pode ser realizado pela adição de fluxantes, sendo comumente utilizado a Fluorita (CaF2), isto porque a Fluorita aumenta a solubilidade de CaO e, por conseguinte, aumenta a capacidade de desfosforação de escória. Apesar disso, alguns estudos advertem sobre o risco de liberação de gás tetra fluoreto de silício, que tem caráter nocivo para o meio ambiente. Outro problema relatado é o aumento do desgaste do revestimento refratário impactando nos custos de produção. Neste trabalho de mestrado o uso de Sodalita Nefelínica como fluxante foi comparado com a Fluorita em relação ao desgaste de refratários a base de MgO-C e à fluidez. Os ensaios consistiram em dopar escória de conversor LD com diferentes quantidades de Fluorita e Sodalita (1, 2, 3, 4 % em massa). Os resultados demonstraram que a Fluorita fornece uma escória com menor ponto de fusão e mais fluida, porém ela causa maior desgaste no revestimento refratário, mais que o dobro do desgaste causado pela Sodalita. Acredita-se que isso tenha ocorrido devido a Fluorita ser capaz de aumentar a dissolução tanto do CaO presente na escória quanto do MgO presente no refratário. Este processo é intensificado pela baixa viscosidade apresentada com este fluxante.
Title in English
Comparative study between fluorite and sodalite nepheline additions in properties of slag from primary steel refining
Keywords in English
Fluorite
MgO-C Refractories
Nepheline
Slag
Sodalite Nepheline
Abstract in English
The control of the slag characteristics from primary refining can be accomplished by adding fluxes, being commonly used Fluorite (CaF2). This happens because the fluorite increases the solubility of CaO and thus increases the ability of the slag dephosphorization. Nevertheless, some studies warn about the risk of releasing silicon tetra-fluoride gas which has harmful character to the environment. Another problem reported is the increased wear of the refractory lining impacting on production costs. In this master dissertation the use of Sodalite Nepheline as flux was compared with Fluorite concerning MgO-C based refractories wear and fluidity. The tests consisted of doping LD converter slag with different amounts of Fluorite and Sodalite (1, 2, 3, 4 % mass). The results showed that the Fluorite provides a slag with a lower melting point and becomes more fluid, but it causes greater wear on the refractory lining, more than double the wear caused by Sodalite. It is believed that this has occurred due Fluorite be able to enhance the dissolution of the CaO in slag as well as MgO present in the refractory. This process is intensified by the low slag viscosity presented with this flux.
 
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EMD14005_C.pdf (4.63 Mbytes)
Publishing Date
2014-11-07
 
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