This study focuses on the viscosity calculation of molten slags using computational thermodynamics. Different slag systems and their measured viscosities from different references were used and compared with those obtained through FactSage software. To calculate the viscosity of each slag the Viscosity module available in Fact-Sage 6.4 was used. In order to perform the evaluation of computational thermodynamics in viscosity calculation, six different slag systems were presented, all of which were formed of calcium-silicate melts. In total, 162 slags, in temperatures ranges from 1423 K (1150 ºC) to 2089 K (1816 °C) were presented for all slag systems. The software showed a tendency to produce viscosity values lower than those found in the literature measured by an experimental method. The relative deviation between the measured and calculated viscosity values is in the range of 13.31 to 37.53% for evaluated systems. Considering all references and systems, the average deviation between measured and calculated viscosities is 23.61%, which, according to literature, is an acceptable value. The CaO-SiO 2 -Al 2 O 3 and CaO-SiO 2 -FeO systems showed the best agreement between the experimental method and the method calculated through FactSage 6.4 with a very good fitting between viscosity values.

ResumoEste estudo foca na análise do comportamento do módulo para cálculo da viscosidade de escórias fundidas do software FactSage 6.4. Foram utilizados dados da literatura e calculada a viscosidade de 972 escórias, no sistema CaO-SiO2-Al2O3-MgO, variando composição dentro da faixa de 2-58% de CaO, 7,4-70% de SiO2, 0-40% de Al2O3 e 0-38% de MgO, e temperatura na faixa de 1050-1750ºC. Foi encontrada uma tendência do software de produzir resultados com valores de viscosidades menores que os encontrados na literatura. O desvio médio entre os valores da literatura e calculados foi de 32,06%, segundo estudos da literatura é considerado adequado para viscosidades de escórias siderúrgicas fundidas. Palavras-chave: Escória; Viscosidade; Termodinâmica computacional. CaO-SiO 2 -Al 2 O 3 -MgO SLAG VISCOSITY CALCULATION USING FACTSAGE 6.4 SOFTWARE AbstractThis study focused on the behavior analysis of the viscosity module of the FactSage 6.4 software. A total of 972 slags were calculated using literature data from the CaOSiO2-Al2O3-MgO system, varying the composition on the range between 2-58% CaO, 0.4-70% SiO2, 0-40% of Al2O3 and 0-38% MgO. The temperature range was from 1050ºC to 1760ºC. The software showed a tendency to produce lower values than the ones on the literature data. The average deviation between the calculated and literature values was 32,06%, which according to literature studies is considered suitable for steelmaking molten slags viscosity.