Application of optical basicity to viscosity of high alumina blast furnace slags

Abstract

The composition and properties of blast furnace slags greatly affect the furnace productivity and the quality of hot metal produced. Viscosity is an important physical property of slags, strongly influenced by the chemical composition, structure and the temperature. Experimental measurement of slag viscosity requires high temperature equipment and is time consuming. Therefore, chemical parameters are used to identify trends in viscosity as function of chemical composition. Limited information is available for High Alumina Blast Furnace Slags, since much of the open literature deals with Low Alumina Slags, with alumina content less than 15 weight percentage. High Alumina slags (alumina content in the range of 15% to 30%) are predominantly encountered in Indian Blast Furnaces. It appears that these slags have higher viscosity and lower sulphide capacity than the low alumina slags. The effect of chemical composition / ionic structure on viscosity has been interpreted in this work, using the chemical parameter of optical basicity. Data reported in the literature have been used, along with the values of liquidus temperature, for high alumina slags. Three slag systems, i.e., CaO-Al2O3-SiO2, CaO-Al2O3-SiO2-MgO and CaO-Al2O3-SiO2-MgO-TiO2 have been considered in this work. The trends observed are discussed in the paper

Correlation between the critical viscosity and ash fusion temperatures of coal gasifier ashes

“…Conversely, several concepts and models from the study of molten silicates are useful in understanding how changes in composition and operating temperature affect coal ash slag viscosity. More specifically, the study of local silicate structure through optical basicity measurements [18] is important in understanding the effect of coal ash slag composition on the viscosity of fully molten slags [19][20][21][22][23]. In addition, the thermodynamics and kinetics of solid phase formation in molten silicates are important factors in understanding the transition from Newtonian to non-Newtonian flow at the critical viscosity temperature.…”

Influence of Al₂O₃ and MgO on the Viscosity and Stability of CaO–MgO–SiO₂–Al₂O₃ Slags with CaO/SiO₂=1.0

“…Thus, the Al 2 O 3 content in the slag will be certainly increased, and then the viscous behavior of the slag will be variation. 6,7) It is well known that Al 2 O 3 is an amphoteric oxide. 8,9) Al 2 O 3 behave as either a basic oxide or an acidic oxide depending on the slag composition.…”

Molecular Dynamics Simulation on the Influence of Al2O3 on the Slag Structure at 1873 K

“…For example, nowadays in China, the Al 2 O 3 content in the blast furnace slag increases by using the Australian ore fines to replace the Brazilian ore fines. The mass percentage of Al 2 O 3 in the slag is usually allowed to be lower than 15% to meet the demand of the blast furnace at present, but if the Al 2 O 3 content is higher in the final slag, the viscosity of the slag increases [1,2] , and the g g y g ( ) flowability and desulphurization ability [3,4] will decrease dramatically, causing various severe problems for the smooth and stable operation of the blast furnace. Owing to viscosity measurements are both time consuming and difficult at high temperatures, a large number of prediction models [1,[5][6][7][8][9][10][11] for viscosity have been developed.…”

“…The mass percentage of Al 2 O 3 in the slag is usually allowed to be lower than 15% to meet the demand of the blast furnace at present, but if the Al 2 O 3 content is higher in the final slag, the viscosity of the slag increases [1,2] , and the g g y g ( ) flowability and desulphurization ability [3,4] will decrease dramatically, causing various severe problems for the smooth and stable operation of the blast furnace. Owing to viscosity measurements are both time consuming and difficult at high temperatures, a large number of prediction models [1,[5][6][7][8][9][10][11] for viscosity have been developed. Molecular dynamics (MD) simulation [2,[12][13][14][15][16][17][18][19] , which is an excellent tool for studying the microstructure with classical dynamics, has been generally used in the metallurgical melt for decades.…”