Utilização de coque com baixa concentração de enxofre na indústria de alumínio.

Abstract

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.