Brief Overview of Aluminium Sector
The Indian Aluminium Industry is the second-largest producer of aluminium globally, with a share of ~5.3% of the global output. In FY21, India produced ~4 million tonnes (MT) of aluminium. The industry is highly concentrated with most of the country’s aluminium being produced by the top five companies. The aluminium industry in India is thriving at an enviable growth rate of 7% per annum, which is one of the highest in the world. Demand for aluminium has grown over the years from various sectors such as construction, electrical, automobile, packaging, etc. The export of primary Aluminium from India has witnessed a rapid rise over the years and the share of exports in aggregate production has risen to 54% in FY20 from 46% in FY16. India's primary Aluminium exports increased by approximately 50% during the first quarter of FY21.
In FY21, India's per capital aluminium consumption stood at 2.5 kg as against the worldwide average of 11 kg and 24 kg of China. According to a NITI (National Institution for Transforming India) Aayog study, enhancing India’s per capita aluminium consumption to the global average would require an annual increase of 16 MT in consumption. The major aluminium-consuming sectors include power (~44%), construction (17%), and consumer durables & transportation (10-12%).
Manufacturing Process & Energy Consumption
The Aluminium manufacturing process comprises of two primary sub-processes; bauxite refining for production of alumina and smelting for productions of aluminium metal and secondary process for conversion to merchant products.Although considerable energy is also used in anode production, this is often accounted for under raw materials. In the overall context, typical distribution of energy usage in different sub-processes is shown below:
|% of Total Energy Consumption
In the refining and anode making process primarily thermal energy is used, for digestion and calcination for the former and baking for the later. However, if the energy content of the coke is also considered, it adds 30% more to the overall energy consumption. Electricity is used for the smelting process. For the secondary process, both thermal and electrical energy are used, thermal energy for die casting, pre-heating and stress relieving whereas electrical energy for rolling and extrusion. Further, all the plants in India have their coal based captive power plants meeting practically the entire power demand of the manufacturing process. Typical fuel mix of Aluminium manufacturing process involves a) Coal (94%) b) Oil (4.5%) c) Gas (0.5%) d) Electricity (1%)
In addition to the basic technology, operation and maintenance also play very important role in maintaining the energy usage. Some of the critical areas of operational control include control of alumina feed rate, cell temperature, current densities, anode management, management of product extraction. Similarly, maintenance includes proper insulation levels and thermal balance, conductivity of various bus bar connections and joints etc.
Flow Process Diagram of one Typical Aluminium Plant
Birdeye of a Typical Smelter Potline of an Aluminium Plant