FIGUEIREDO, F. E. O.; FIGUEIREDO, Francisco Euésali de Oliveira.
Résumé:
The demand for aluminum in the domestic and international market has grown
dramatically over the past two decades due to its versatility of application, from simple
consumer to naval, automotive and aerospace segments. The three main raw materials for
aluminum production are electricity, alumina and anode, in that order of importance. The
anode is made of calcined petroleum coke and coal tar pitch. The first is the main byproduct
of petroleum refineries and the second is the byproduct of the metallurgical coke production
for the steel industry. The demand for coke has been accentuated in the last two decades, not
only for the aluminum market, but also from other markets that demand this same coke, like
titanium and carbon industries. This increase in coke demand has promoted its scarcity in the
market and restricted also its quality. The above limitations imposed on the aluminum market
the need to seek alternatives to compensate the loss of coke quality. The loss more sensitive
to the aluminum industry was sulfur, which had the range from 2.8% to 3.2% to 0.8% to
1.0%. Sulfur is important because it works as an inhibitor on the alumina (AI2O3) electrolysis,
increasing anode performance. This work presents an alternative to use low sulphur coke
through the blending of fractions in order to promote a selective reaction, without
considerable losses for the electrolytic process. With 95% interval confidence, by Analysis of
Variance (ANOVA), the results show that the blending of fractions, or selective blending,
presents itself as an alternative to the use of low sulfur coke in the aluminum industry, and
breaking the paradigm of that only high sulfur coke can have a high performance in the result
CO2 Reactivity Residue. In financial terms, blending by fraction represents a saving of US$
1.2 million per year for Aluminum S/A.
