A NOVEL CHEMISTRY FOR IMPROVED ALUMINATE SCALE CONTROL IN BAYER PROCESS

摘要

In the Bayer Process for the production of alumina, autoprecipitation of alumina trihydrate in the decantation, security filtration, and mud washing circuits results in both alumina losses and problematic deposit buildup on vessel surfaces. Moreover, auto-precipitation is a key limiting factor in improving plant production by limiting the A/C ratio of digestion. As a result, reduction of this scaling and/or prevention of auto-precipitation in these vessels can significantly improve overall plant performance. While chemical methods to control scale formation, such as Nalco's SCFA (Scale Control Filtration Aid) programs, are well established and widely used within the industry, significant opportunity for additional improvement still remains. In this work, a new, more effective, polymer based chemistry for the prevention of trihydrate scale in thickeners, washers and filters has been developed. This paper provides details on this experimental chemistry to further reduce auto-precipitation without downstream effects in the Bayer process.