I. Arvanitidis

A study of the thermal decomposition of BaCO3

In the present work, the decomposition reaction, BaCO3 (solid) = BaO (solid) + CO2 (gas), was investigated by thermogravimetric analysis (TGA) and differential thermal analysis (DTA) methods. Both shallow powder beds and densely compacted spheres of the carbonate were employed. In the case of the shallow powder beds, TGA and DTA were carried out simultaneously. The DTA curves showed that BaCO3 exhibited two phase transformations, the transformation of orthorhombic to hexagonal occurring at 1079 K and that of hexagonal to cubic at 1237 K. The activation energy and the forward reaction rate constant of the decomposition of BaCO3 were evaluated from the thermogravimetric results of the powder beds. The activation energy of the decomposition was found to be 305(± 14) kJ • mole−1. The experimental results obtained with the compacted spheres were compared with those corresponding to the powder beds. After the initial stages, the formation of liquid due to the eutectic reaction between BaCO3 and BaO appears to play an important role in the reaction kinetics.

Physical modelling and control of dynamic foaming in an LD-converter process

This paper deals with physical modelling and control of dynamic foaming in the LD-converter process. An experimental setup consisting of a water model, DSP and PC hardware is built up and shown to be useful for studying dynamic foaming. Furthermore, a foam height estimation algorithm is presented and validated through experiments. Finally, sound signals from the LD-converter and water model are compared and similarities between them are found.

Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen

The isothermal reduction of synthetic CoTiO3 and NiTiO3 in hydrogen (1 atm) was investigated using thermogravimetric analysis technique in the temperature range, 928-1287 K (CoTiO3) and 884-1387 K ...

Investigation of the kinetics of reduction of iron titanate (FeTiO3) by hydrogen

In the present study, the reduction kinetics of synthetic ilmenite by H 2 has been carried out using thermogravimetric technique. This has been complemented by X-ray diffraction and scanning electron microscopic (SEM) analyses. The morphology of the reduced product shows that iron metal is distributed around the titanium oxide particles, which has important implications for the separation of iron and titanium dioxide in the recovery of the same from ilmenite. The reduction proceeds very fast in the initial period and a high degree of reduction is obtained in the case of all reductions. A decrease in the reaction rate is observed at later stages of the reduction due to the slow diffusion process. An activation energy for the reduction of FeTiO 3 to iron and titanium dioxide was estimate to be of 108 kJ.mole -1 .

Foam Level Control in a Water Model of the LD Converter Process

This paper deals with estimation and control of foam level in dynamic foaming. An improved foam level estimation methodology from a microphone signal and its automatic calibration is presented. The dynamical reaction of the foam level on air lance movements is modelled using system identification. Based on the resulting mathematical model, a controller for foam level stabilisation is designed and applied to a water model, representing the LD converter process. It is shown that the foam level can be controlled using a microphone as the measurement device and air lance movement as the actuator.