Analysis on the die compaction of anode paste material used in aluminum production plants

The quality of anode electrodes is an important issue in aluminum production plants. Therefore, not only raw material conditions but also the conditions of different production steps could affect the anode quality. Analyzed in this paper is the die compaction of some anode paste samples with specified compositions. Portions of fine coke and coarse coke particles were mixed and some coal tar pitch was added to this mixture in order to make the anode paste sample. The Blaine number of the fine coke portion and the pitch content were selected as two variables to make different anode paste samples. Thereafter, each sample was compacted in a rigid die while applying a uniaxial stress up to 60 MPa. The compaction behavior of different samples was studied and an analytical relationship between the green relative density and the axial pressure applied in the die was suggested. After having identified the parameters of the suggested expression for each sample, the contribution of the rearrangement phenomenon to the material densification was studied. Regarding the good agreement between the suggested relationship and the experimental results, it would be possible to predict the compactability of different anode pastes based on the analytical equation.