Slide Background
Slide Background

A CASE STUDY IN DOWNSTREAM TESTING OF BAYER PROCESS ADDITIVES

Gotsis, S. Harrison, I. Ioppolo-Armanios, M. Kildea, J.

The use of chemical reagents to enhance the productivity of alumina refineries has become widespread in a number of areas of the Bayer process. Additives such as flocculants to assist in mud separation have been extensively used for some time, but reagents are now being used in such diverse areas as mud filtration, aluminium hydroxide precipitation and classification, product dewatering and mud disposal. With the ever increasing complexity of the Bayer process, it is important to recognise the possibility that some additives which are beneficial in one area of the refinery, may adversely affect other down-stream processes. Alternatively, there may be undesirable interactions between two or more additives used for different purposes. In order to avoid such potential problems a thorough understanding of both additive chemistry and Bayer process chemistry is required. One way of achieving this is for supplier and customer to work in close partnership to develop, test and implement new reagents.

In developing a range of reagents for the control of oxalate in Alcoa’s refineries, the effects of the reagents on downstream processes have been carefully investigated. As well as developing a number of tests to assist in the full assessment of the reagents, the interactions of both the reagents and their degradation products with other additives in the system were considered. The cooperative research leading to the development of these reagents, their downstream testing and plant implementation are presented as a case study.