Glimpse of Most Energy Efficient HTD Alumina Refinery in the World

Hi Friends,

In earlier posts, we have discussed about the Alumina refineries operative with Tube Digestion System covering its technological features, advantages and disadvantages as well. We have clearly focused on salient features of different technologies available and established so far.

In present post, we wish to discuss about the Industry benchmark of thermal energy consumption in processing Boehmitic Bauxite adopting High Temperature Digestion (HTD) technology for alumina production with specific figures of one of the Alumina refineries in the World having lowest energy consumption among Alumina plants processing Boehmitic Bauxite. As stated earlier, thermal energy consumption for high temperature digestion plants generally ranges from 15 to 16 GJ/tonne alumina as against about 10 GJ/tonne of alumina for processing Gibbsitic Bauxite adopting Medium pressure digestion technology. For processing of Boehmitic Bauxite, Tube digestion system with efficient heat recovery system has been found to be most energy efficient compared to other HTD techniques as total energy requirement drops drastically to the level of around 12 GJ/tonne of alumina because of high heat transfer co-efficient across tube digesters coupled with integrated evaporation system.

The bird's eye view of the Alumina refinery operative with Tube digestion and integrated evaporation system adopted for processing Boehmitic Bauxite at around 270 degree centigrade is given below. The present operative  capacity of this plant is 925 ktpa calcined alumina and Natural gas is the fuel used for generating steam for supply to process. This  Alumina plant is operative with Tube digestion technology since 1974 for production of alumina on commercial scale. The initial capacity of this plant was 500 ktpa which was upgraded to 925 ktpa afterwards by increasing the throughput flow of slurry from 280 m3/hr to 340 m3/hr and other minor modifications.

View of  Most Energy Efficient Operative Alumina Refinery in the World 

The energy consumption in Digestion area is estimated at around 3.0 GJ/tonne of alumina. This Alumina refinery consumes thermal energy to the tune of 7.0 GJ/tonne of alumina for the Bayer process area which is the Industry benchmark of lowest energy consumption in processing Boehmitic Bauxite for alumina production. In addition to this, the plant consumes purchased electrical power equivalent to about 1 GJ/tonne of alumina. This plant has Natural gas based stationary calciner wherein the total energy consumption is about 3.0 GJ/tonne alumina. Thus, total energy consumption in this efficient Alumina refinery works out to about 11.0 GJ/tonne of calcined alumina. This recorded figure is about 10% less compared to those of other existing Alumina refineries adopting similar process technology. We salute the technologist, plant designer and management team of this Alumina refinery for creating a new benchmark of lowest energy consumption for alumina production in the World for processing of Boehmitic Bauxite in Alumina refinery.


Hope, the above gives a guideline to us for designing the system with further improvements in forthcoming Alumina refinery in any part of the globe.


Please put your views / suggestions / remarks / comments, if any.
Regards.


Kunwar Rajendra