Aluminium is a durable metal that has been available to humanity approximately 200 years ago. It is among the modern metals that we have in the world. Aluminium currently is produced at a higher rate compare to nonferrous metals combined. It was about 58 million Metric Tons as per the production statistics of 2015. From that, about 25 million were reused. Interestingly, to this far around 1 Billion Tons of the aluminium has been extracted. The 75% of the ever-produced aluminium is still being used by humankind considering the durability and recyclability of the metal.
Since the introduction of the Bayer processes and Hall-Heroult to the field of aluminium smelting has brought drastic changes. Bayer Process helps in the extraction of aluminium from the Bauxite. The Hall-Heroult process produces the molten aluminium through electric reduction of the alumina, which has been dissolved in the electrolyte made up of cryolite.
Technological changes also happened and affected the production of aluminium metal. The significant change that occurred was the preparation of carbon anode using petroleum coke and the pitch, for example, the Soderberg process. In the Soderberg, process anode is not made to bake at a different plant. The Soderberg cell contains only one massive anode inside the pot. Addition of the green paste from the upper part of the container will help in the baking of the green anode as the dough moves from the first part of the pot to the bottom. Unfortunately, when the quality of the baked Soderberg anode is assessed, it is noted that its quality is lower than that of the prebaked anode. Thus, the Soderberg cells will display current owner effectiveness, and the higher pot voltage is needed to bake the anode.
“Prebake” system is universally replacing the Soderberg process. “Prebake” system has the node being prepared outside the container and then baked in the anode-baking furnace in another part to manage the emissions and ensure the production is environmentally friendly.
Extensive research has been carried out accompanied by comprehensive experiments to identify the most innovative technology to be used in aluminium smelting. There is a need for more productive, sustainable and energy intensive technology. The three major requirements that govern the development of the new aluminium smelting process include:
- Reduction of electrical power
- Modification of the capital cost for the production per ton
- Environmental considerations
The alternative technologies that are very common, have been applied in aluminium smelting, and produce several patents to this time include:
- Inert Anodes in electrolysis cells
- Carbothermic production of aluminium
Experiments are being carried out on these methods to establish the unknown commercial viability.
Aluminium smelting process needs improvements to be more environmentally friendly. Focus currently is to reduce energy consumption, stop the emergence of anode effects and to lower use of the carbon anode. However, the alternatives processes show more or even less energy intensity. High temperatures are involved, and the reactor life and materials constructions do not disappear faster.
The process limitations that major players face regularly include energy savings, optimum productivity, and cost cutting. The process starts with the identification of raw materials the energy and the smelting operations. There is a need to use the right equipment and try to recycle some waste products when possible. The smelters are using the advanced kind of technology that saves energy and is more effective. It includes; pot-control system, the online device in the pot to switch on off and the treatment plant with the casting devices to boost productivity and save energy.
The primary Aluminum producers need the volatility of the commodity present on the market, low LME aluminium and premium prices and proper plans to bring cost efficiencies for them to survive profitably. Energy efficiency is the driver of the business and not only the desire of the environment. The low carbon dioxide primary aluminium is a necessity; there should be the proper use of the waste materials and the aluminum producers, equipment suppliers and the active technology providers. It will bring significant roles in aluminum smelting.
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