Dissolution of Lime in Synthetic ‘FeO’‐SiO₂ and CaO‐‘FeO’‐SiO₂ Slags

Abstract

Dissolution of different CaO samples into molten synthetic ‘FeO’‐SiO2 and ‘FeO’‐SiO2‐CaO slags was carried out in a closed tube furnace at 1873 K. The slag was kept stagnant. It was found that the dissolution rate was very fast when CaO rod was dipped into ‘FeO’‐SiO2 slag. In the case of ‘FeO’‐SiO2‐CaO slag, the dissolution of CaO rod in the stagnant slag was retarded after the initial period (2 minutes). Only less than 16 percent CaO reacted with the slag, irrespective of the type of lime. Three phase‐regions were identified in the reacted part of the lime rod by SEM‐EDS analysis. The formation of these regions was explained thermodynamically. A dense layer of 2CaO · SiO2 was found to be responsible for the total stop of the dissolution. It could be concluded that constant removal of the 2CaO · SiO2 layer would be of essence to obtain a high dissolution rate of lime. In this connection, it was found necessary to study the dissolution of lime in moving slag to reach a reliable conclusion regarding the relevance of the reactivity obtained by water ATSM test to the real reactivity of lime in high temperature slag.

Influence of Magnesium Oxide Content on Kinetics of Lime Dissolution in Steelmaking Slags

“…The maintained heating rate was 400°C per hour. The desired temperature of the process was reached and held for 30 minutes, lime samples heated up to the same temperature in order to limit the thermal buoyancy, respectively, were added into the melt with the density of 2.9 g/cm 3 . Lime samples were prepared in the form of cylinders with height of 1.72-1.75 cm, diameter of 0.5 cm and density of 3.0 g/cm 3 using press machine.…”

“…Elizaveta CHEREMISINA, 1) * Johannes SCHENK, 1) Ludwig NOCKE, 2) Alexander PAUL 3) and Gerald WIMMER 4) 1) Department of Metallurgy, Montanuniversität Leoben, 8700 Austria.…”

Thermal Conductivity of 2CaO·SiO₂ Bearing Solid Solution

“…ated from lime matrix. 4) Carbon dioxide and steam gas generated by the thermal decomposition of CaCO 3 , that is remained limestone after calcination, and Ca(OH) 2 which was formed by absorption of moisture in the air, can crush the 2CaO·SiO 2 layer on the surface of the lime. These thermal decomposition reactions are endothermic; thus, supply of heat from molten slag to lime is essential and thermal conductivity is necessary to postulate this thermal behavior.…”

“…Dissolution of lime into molten slag would proceed by two step reactions, namely, the formation of 2CaO·SiO 2 on the surface or in the vicinity of the lime and dissolution of 2CaO·SiO 2 into molten slag, where the rate-controlling step is regarded as mass transfer of 2CaO·SiO 2 in the slag phase. [1][2][3] To promote the dissolution of lime, elevation of temperature is a key factor because the solubility of 2CaO·SiO 2 would greatly depend on the temperature and increase with its elevation. For proper understanding of thermal condition regarding lime dissolution, thermal conductivity of 2CaO·SiO 2 is the most essential information.…”

Influence of P₂O₅ on Dissolution Behavior of Lime in Molten Slag

“…For example, many researchers [1][2][3] have reported that a 2CaO·SiO 2 layer is formed around lime during its dissolution into molten slag; this layer prevents further dissolution of lime. Noguchi et al 4) reported that the high content of FeO x in the CaO-SiO 2 -FeO x slag promotes…”