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Calcination of gibbsite or hydrate into alumina accounts for around 30% of the energy consumption of the Bayer process. The introduction of new technologies, such as the circulating fluidised bed (CFB) calciners, from the 1960s onwards reduced the energy consumption by up to 30% compared to that of rotary kilns. Since then efforts to reduce energy consumption have continued, and a comparison is made between some of them. The paper looks at their complexity, and effects on capital and operating costs, and process control., Calcination of gibbsite or hydrate into alumina accounts for around 30% of the energy consumption of the Bayer process. The introduction of new technologies, such as the circulating fluidised bed (CFB) calciners, from the 1960s onwards reduced the energy consumption by up to 30% compared to that of rotary kilns. Since then efforts to reduce energy consumption have continued, and a comparison is made between some of them. The paper looks at their complexity, and effects on capital and operating costs, and process control.

Changes in the Bayer process have been driven by a combination of environmental and energy factors, as well as changes in the product specifications caused by developments in the Hall-Heroult process. This has led to a coarser particle size distribution, higher specific surface areas and a lower attrition index of alumina. There have also been changes in precipitation, the conversion strategy and the use of more energy-efficient stationary calcination processes. The authors present the history, science and future of alumina calcination, discussing how new scientific tools and insights are changing the way alumina is defined., Changes in the Bayer process have been driven by a combination of environmental and energy factors, as well as changes in the product specifications caused by developments in the Hall-Heroult process. This has led to a coarser particle size distribution, higher specific surface areas and a lower attrition index of alumina. There have also been changes in precipitation, the conversion strategy and the use of more energy-efficient stationary calcination processes. The authors present the history, science and future of alumina calcination, discussing how new scientific tools and insights are changing the way alumina is defined.

Developments are described in large circulating fluidised bed (CFB) alumina calcining technology and equipment. Aspects discussed include improved energy efficiency, operability and safety, modifications to the process flowsheet by rearranging the fluid bed coolers and re-design of the connection between the fluid bed cooler and the lift duct to provide more stable operation. The use of a modular pre-assembly approach for plant construction can improve cost efficiency, and the benefits are illustrated using the example of an installation at Gove in the Northern Territory, Australia., Developments are described in large circulating fluidised bed (CFB) alumina calcining technology and equipment. Aspects discussed include improved energy efficiency, operability and safety, modifications to the process flowsheet by rearranging the fluid bed coolers and re-design of the connection between the fluid bed cooler and the lift duct to provide more stable operation. The use of a modular pre-assembly approach for plant construction can improve cost efficiency, and the benefits are illustrated using the example of an installation at Gove in the Northern Territory, Australia.