•The linked ways between the [SiO4] and [AlO4] tetrahedrons were clarified in detail.•The charge-balancing capability of basic oxides was quantified for [AlO4].•The relation between structure and viscosity in Ti-bearing slag was established.Structure of the CaO–SiO2–Al2O3–MgO–TiO2 slag was studied by molecular dynamics simulation at 1773 K. Additionally, part of viscosities were measured for quantitatively establishing the relationship between the structure and viscosity with varying basicities and TiO2 additions. Role of TiO2 as basic oxide was verified and it can be inferred that the structure of TiO2 is relatively similar to MgO compared to CaO. In addition, distribution of three different types of O was presented from which it can be obtained that nonbridging oxygen preferentially localized beside Si rather than Al. Moreover, parameter αM was proposed to estimate charge-balancing capability of M for [AlO4] (where M denotes Ca2 +, Mg2 +, Ti4 +) along with the average values of αCa, αMg and αTi equaling to 1.731, 1.282 and 1.092, respectively, suggesting that Ca2 + is preferentially compensated for [AlO4] than Mg2 + and Ti4 +. Therefore, TiO2 and MgO have a prominent effect on depolymerizing the framework of the slags than CaO in slags containing high Al2O3. Finally, the natural logarithm of the measured viscosities exhibit a linear dependence on the fraction of Q4 for Si, indicating that the degree of polymerization for Si is still the principal factor which affects the viscosity despite the complicated composition.

•The pyrolysis characteristics of the coal used in the COREX process were studied.•The pyrolysis process of the coals could be divided into four stages.•The heating rate mainly influences the primary pyrolysis stage of the coal.•The second order reaction and third order reaction can give a better representation of the main pyrolysis process.The pyrolysis characteristics of the coal used in the COREX process were investigated by thermogravimetric–mass spectrometric analytical technology. Firstly, thermal behavior of Xinglongzhuang coal and Datong coal was studied under an argon atmosphere at a heating rate of 20 °C/min. Then, the effect of heating rate on pyrolysis of Xinglongzhuang coal was analyzed. In addition, the kinetics of the pyrolysis process was calculated for two coal samples. Results show that the pyrolysis process of the two coal samples has similar characteristics which could be divided into four stages, and the main pyrolysis temperature range of this coal type is from 300 °C to 800 °C. The heating rate mainly influences the primary pyrolysis stage of the coal, while the maximum weight loss rate and corresponding temperature change with increasing of heating rate. The evolved gas species vary as the heating rate increases, and the evolution of CO below 800 °C is similar to that of CO2 which can be attributed to the decomposition of the same functional groups. The second order reaction and third order reaction can give a better representation of the main pyrolysis process with the apparent activation energy ranging from 100 kJ/mol to 200 kJ/mol.