LAYERED DOUBLE HYDROXIDES IN THE BAYER PROCESS: PAST, PRESENT AND FUTURE

摘要

Alumina refiners have been aware of some of the potential uses of Layered Double Hydroxides (LDH's) in the Bayer process for more than a decade. By virtue of their lamellar structure, the ability to adjust the separation of these layers, and the reactivity of the interlayer region, LDH's can be used for the controlled addition or removal of a variety of species, both organic and inorganic. In this paper, we review the history and present use of LDH's in alumina refining, particularly the most commonly used calcium and magnesium aluminate varieties. We also examine some of the ways in which these LDH's can be produced in the refinery, both intentional and unintentional, as well as some of the possible reasons they have not found more widespread application. Finally, we discuss how LDH technology might be applied to deal with emerging trends and issues in alumina refining, particularly in reducing the environmental impact of alumina refining.