Bayer Liquor Analysis by Infra-Red (BLAIR) for Process Liquors

PROJECT HIGHLIGHTS

1. The BLAIR and Rio Tinto Alcan A, C, S and TOC liquor values were shown to be similar.

2. A BLAIR system was shown to be capable of estimating oxalate in a process liquor.

3. The BLAIR system was able to determine differences in breakdown for liquor organics.

4. BLAIR was demonstrated as a fully automated system.

BLAIR (Bayer Liquor Analysis by Infra-Red) is a fast and convenient method of chemical analysis for Bayer liquors developed at Central Chemical Consulting. BLAIR is a spectroscopic based technique which requires no titrations, liquor dilution or additional reagents. In this work, BLAIR measurements were recorded for process liquors supplied by Rio Tinto Alcan, and for synthetic Bayer liquors prepared at Central Chemical Consulting. These results were compared with measurements conducted at Rio Tinto Alcan using their current routine methods. A good correlation was obtained between the BLAIR and Rio Tinto Alcan results. The precision of the BLAIR analyses were approximately the same and in some cases higher than those from the currently used methods.

To achieve a further improvement of correlation between the methods, particularly for TOC, the BLAIR analytical model was modified to account for the differences in organic content between liquors. The BLAIR system was used to estimate the oxalate content of the liquors. The BLAIR analytical model was also used to give an indication of the breakdown and relative amounts of low and high molecular weight organics in the liquors.

BLAIR was fully automated during the course of this project, which is far beyond the initial project objective. The automation was accomplished with the use of a flow through cell in conjunction with an autosampler. The automated system was used to run over 40 repeats of a synthetic liquor sample over several days, with what we consider is acceptable reproducibility for this early stage. Following its development and during the time of testing in this project, no problems were encountered with the automated system.

The next stage of work will require further testing and on-site trials of the automated BLAIR system. Further development and improvements to parts of the BLAIR hardware and software are also planned.

from: “Bayer Liquor Analysis by Infra-Red (BLAIR) for Process Liquors” MERIWA Report 298, Vincent A. Patrick, Emmanuel Karakyriakos, Bob van Emden, Martin Finn and Robert Patrick, March 2013. ISBN 1920981594.