Improvement of carbon anode quality in view of reducing energy consumption and environmental emissions in aluminum industry

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The global objective is to improve anodes by developing new technologies, which are not yet used in industry, in view of reducing energy consumption and greenhouse gas (GHG) emissions. They are original and fundamental in nature. Project 1- Utilization of graphene in anode production: The energy consumption is a major part of the aluminum production cost. Improving anode quality decreases the cost, energy, carbon consumption, and GHG emissions. Graphene conducts electricity efficiently. It has been the subject of many innovations, but it was never used in anodes. Replacing a small part of coke with graphene could decrease the anode electrical resistivity, hence energy consumption. The study also aims to produce graphene from rejected anodes instead of graphite to add value to industrial rejects. This has never been done before. Project 2- Rheological behavior of anode paste: A new tool will be developed to understand the rheological behavior of anode paste and correlate this with anode properties. This will make the assessment of anode quality possible from the paste quality before anode production. It will also permit the determination of the optimum pitch quantity, which is currently adjusted by trial and error in plants. Project 3- Utilization of high softening-point pitch (HSPP) in anode making: The low softening-point pitches release volatiles containing PAHs during anode baking and increase the GHG emissions. HSPPs have lower volatile content, which would decrease the GHG emissions. However, the volatiles provide half of the energy needed for anode baking. A decrease in volatiles will increase the fuel requirement. The objective is to determine the impact of using HSPP on anode quality, cost, and GHG emissions. Project 4- Anode assembly without using cast iron: Anodes are paired with an anode assembly and installed in an electrolysis cell. The anode assembly consists of steel stubs that fit into anode holes, a crossbar that connects the stubs, and a rod that is attached to the crossbar. Hot cast iron at is poured into the space between the stubs and the anode carbon to hold them together. The electrical resistances of cell components affect energy consumption. In this project, a new anode assembly will be developed, which will eliminate the utilization of cast iron and hence anode/cast iron and cast iron/steel interface resistances, reducing the energy consumption. Also, the amount of anode butts produced will be reduced since a larger portion of the anodes can be used for the electrolysis.