Kamran Azari

Effects of Physical Properties of Anode Raw Materials on the Paste Compaction Behavior

The current study investigates the effects of coke particle characteristics and paste formulation on the flowability and the compression behavior of anode pastes. Shape factor and texture of different fractions of cokes were characterized using an image analysis system where the characteristics of each coke were correlated to its vibrated bulk density (VBD). A compression test was designed to study the effects of particle characteristics and paste recipe on the compactability of pastes. The test was applied on four anode pastes, prepared from different coke types, particle size distributions and pitch contents. It was observed that the compression test is significantly sensitive to any changes in raw materials characteristics and formulations. Consequently, the compression test may be used as a tool for evaluating anode quality in relation with material variations.

Influence of Mixing Parameters on the Density and Compaction Behavior of Carbon Anodes Used in Aluminum Production

The current study investigates the effects of mixing parameters on the quality of anode paste and green anode used in aluminum electrolysis. Four mixing times and four mixing temperatures were applied to prepare anode pastes using calcined petroleum coke and coal tar pitch, as raw materials. The volume of the pores in the paste was used as the indicator for mixing effectiveness. A compression test was applied to the pastes to study the compactability of these pastes and to investigate the effect of mixing parameters on density of the green samples. It was shown that mixing parameters influence the size, volume and surface area of paste porosity and also its compaction behaviour.

Discrete Element Method Applied to the Vibration Process of Coke Particles

Physical properties of coke particles including particle shape and size distribution have direct effects on their packing density. In the present work, effects of particle shape and size distribution on vibrated bulk density (VBD) of dry coke samples have been investigated. Discrete Element Method (DEM) has also been used to simulate the vibration process. Results showed that the shape and size distribution of particles influence the bulk density of coke and these parameters can be used to describe the packing density of coke particles. In general, mixed samples provide higher VBD than mono-size samples and as the fraction of coarse particles increases vibrated bulk density increases. However, existence of 10 wt.% of fine particles to fill the pores between coarse particles is essential. Simulation results were also reasonably consistent with experimental data. Finally, it is noteworthy that a well-tailored DEM model is capable of predicting the particle rearrangement and density evolution during the vibration process.

Characterization of Homogeneity of Green Anodes through X‐Ray Tomography and Image Analysis

Homogeneity of green anode has a direct effect on final properties of baked carbon anodes. This work aimed to study the influence of mixing parameters on the homogeneity of laboratory-scale anodes. Anode pastes were made using different mixing times and temperatures and then underwent a compaction procedure. Homogeneity was characterized by the distribution of coke, pitch and porosity throughout the anodes as well as the variations in binder matrix thickness (fine coke + pitch). X-ray tomography was used as a non-destructive tool to evaluate the material distribution within the samples. The microscopic images of the green samples were analyzed to measure the mean thickness of binder matrix. The lowest variations in material distribution and the minimum thickness of binder matrix were obtained for the sample mixed at 178 °C for 10 minutes. The most homogeneous sample with the lowest binder matrix thickness had the maximum green and baked apparent density.