Determinação simultanea, em linha, da concentração de soda caustica e de alumina em solução de aluminato de sodio do processo bayer de produção de oxido de aluminio

AUTOR(ES)

Eduardo Marchioni Escobar

DATA DE PUBLICAÇÃO

2004

RESUMO

The objective of this project is the development of an automatic in line system to measure the alumina and caustic content in the sodium aluminate solution of the Bayer Process by using sensors and chemometrics calculations. The aluminum process production begins with the Bayer Process to extract the aluminum oxide from the bauxite, the aluminum ore. Then, the aluminum oxide is reduced to metallic aluminum by electrolysis. The Bayer Process consists of dissolving the hydrated aluminum oxide present in the bauxite with hot caustic soda solution, producing a supersaturated sodium aluminate solution. The control of the alumina and caustic concentration in the sodium aluminate solutions of the Bayer Process is very important to prevent the autoprecipitation of the hydrated aluminum oxide and to optimize the production efficiency.The caustic and the alumina concentrations are determined in the laboratory analyzing many samples that are collected in one hour minimum interval, in different points of the productive process making the automated and continuous process control not feasible. An in line system using a densimeter, a conductivity meter, a thermometer and a multiple linear regression mathematical models can be used to predict the caustic and aluminum concentration but the precision is not suitable to allow the automated control of the aluminum extraction step in the Bayer process. The principal components regression methodology (PCR) apptied to autoescaled data of density, conductivity, refractive index and temperature of the sodium aluminate solution used to construct mathematical models plus instruments and the analytical method precision improvement was developed to predict alumina and caustic concentrations with the required precision to automatically control the alumina extraction step of the Bayer Process.

ASSUNTO(S)

processo bayer alumina aluminio quimiometria

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