A Review of the Factors Affecting the Thermophysical Properties of Silicate Slags

Abstract

This paper is dedicated to the memory of the of Prof. Masanori Iwase and his life and work. The factors which affect the thermophysical properties of silicate and aluminnosilicate slags are reviewed. These include (i) the polymerisation of the silicate network (ii) various cation effects and (iii) temperature. Of these, the degree of poly merisation of the silicate network (expressed here through the parameter Q (= 4NBO/T)) is the most important and the viscosity (η), electrical resistivity and thermal conduc tivity all increase as Q increases. Various ways in which different cations affect the properties are considered for each individual property viz. the -M-O bond strength affects (i) liquidus temperature (ii) activity coefficient of SiO 2 and (iii) thermal expansion coefficient and whereas both the size and number of available cations affect the electrical conductivity and resistivity.The following observations were made: i. There is less scatter in property data for liquid slags at a specific temperature than that for the liquidus temperature. ii. The relation between Arrhenius parameters, ln A and B for viscosity and electrical resistivity is nonlinear. iii. The magnitude of the thermal conductivity (k) in solid slags is related to the rigidity of silicate network and the rapid decrease in k with increasing temperature occurs at a temperature where the viscosity reaches η = 10 6 dPas. iv. The introduction of Al 2 O 3 into the silicate chain results in significant changes to the propertiesThe ways in which the various properties can be calcu lated from chemical composition are outlined.

Thermal Conductivity of Molten Li2O–B2O3 and K2O–B2O3 Systems

“…For this reason, in the present system, the effect of cation on the oxide structure was evaluated using the ionization potential ( Z/r 2 ); which is the ratio of the charge of the cation ( Z ) to the square of the cation radius ( r ) . The calculated ionization potential was determined as 1.73, 0.96 and 0.53 for Li 2 O, Na 2 O, and K 2 O, respectively . Therefore, it can be inferred that the rigidity of the structure is in the hierarchy order of Li 2 O–B 2 O 3 > Na 2 O–B 2 O 3 > K 2 O–B 2 O 3 .…”

“…The relationship between the thermal conductivity and the ionization potential in the R 2 O–4B 2 O 3 system at 1273 K. (The black dashed line has been drawn as a guide)…”

Influence of B2O3and Basicity on Viscosity and Structure of Medium Titanium Bearing Blast Furnace Slag

“…It is generally known that structure of metallurgical slag is very complex and physical properties are very dependent on the level of polymerization of silicate network. We prefer the parameter, , to be an evaluation of the polymerization of the melt, which can be calculated by the following [14][15][16]:…”

A phase‐field model for the study of isothermal dissolution behavior of alumina particles into molten silicates

“…Although the introduction of network-breaking cations cannot alter the nature of the anionic units, it promotes the formation of high concentrations of more depolymerized units. 62 Thus, Al 3+ cations result in more polymerized units that decrease the dissolution rate of the alumina inclusion particle. Using the information in Table 2, the (z/r 2 ) values of Ca 2+ and Mg 2+ equal 2.04 and 4.59, respectively, which means that Mg 2+ has a stronger polarizing power than that of Ca 2+ .…”

“…Meanwhile, a Ca 2+ or Mg 2+ needs to charge balance for two Al 3+ cations, which leads to a decreasing number of available cations for network-breaking. 62 Thus, Al 3+ cations result in more polymerized units that decrease the dissolution rate of the alumina inclusion particle. The specific coefficient of Al 3+ term is much smaller than that of Si 4+ in the BI, which indicates that Al 3+ cation has a weaker bond strength than Si 4+ in tetrahedral coordination.…”