Main approaches to energy conservation and consumption reduction in the electrolytic aluminum industry

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Main approaches to energy conservation and consumption reduction in the electrolytic aluminum industry: Improve the efficiency of the power supply system; promote the use of thyristor rectifier devices; upgrade existing diode rectifier systems technically; increase rectification efficiency and reduce electrical losses during power supply; lower the average voltage of the electrolyzer to reduce unnecessary energy consumption; reduce E-reverse, i.e., lower overvoltage; increase the conductivity of the electrolyte, thereby reducing voltage drops across it; improve the control level of the electrolyzer to reduce the anode effect coefficient; reduce cathode voltage drops; increase current efficiency by reducing voltage drops across the anodes. Other main approaches include phasing out small-scale pre-baked aluminum electrolyzers with high energy consumption, optimizing the product chain, improving process efficiency through optimized processes for baking, starting up, and operating aluminum electrolyzers; optimizing anode replacement procedures to minimize downtime; innovating in technologies for major repairs of electrolyzers to extend their lifespan; and strengthening resource management. It is also important to rely on independent innovation to achieve sustainable development.

1. Promote the use of “Sail” switch technology to ensure stability in production systems. The multi-point parallel operation of “Sail” switches enhances the stability of aluminum electrolysis processes.
2. Develop technologies for recovering and utilizing waste heat from aluminum electrolyzers: optimize the temperature distribution within the electrolyzer; select appropriate heat exchange media, electrolyzer steel shell materials, and containers for storing these media; increase the energy utilization rate from the current 48% to around 60%.
3. Innovate new low-temperature aluminum electrolysis processes: understand the characteristics of low-temperature aluminum electrolysis; use mathematical simulations to analyze changes in temperature, electromagnetic, and flow fields in such electrolyzers; reduce the electrolysis temperature from around 950°C to below 900°C, thereby reducing direct current consumption to 12,000–12,400 kWh/tAl.
4. Optimize new low-voltage, low-emission aluminum electrolysis processes: develop technologies for producing fully graphitized carbon/titanium boride composite cathodes; develop antioxidant, highly conductive, and electrocatalytic carbon anodes; optimize the gas collection systems in electrolyzers to increase their efficiency from less than 98% to over 99%; explore process control techniques for low-distance aluminum electrolysis and low-voltage operation to ensure stable performance, with an anode effect coefficient of less than 0.05, and reduce CFn greenhouse gas emissions by more than 50%.
5. Industrialize technologies for the comprehensive utilization of solid waste from aluminum electrolyzers: use flotation to recover carbon powder and electrolyte; the recovered carbon powder can be used to manufacture anode protection rings, cold ramming pastes, or cathode carbon blocks, thus enabling the reuse of waste cathode carbon blocks; use physical and chemical methods to recover electrolyte and silicon carbide powder; the electrolyte can be reused in aluminum electrolyzers, while silicon carbide powder can be used to manufacture silicon carbide bricks for electrolyzers, thus enabling the comprehensive utilization of silicon carbide; waste refractory materials can be used to produce aluminum-silicon alloys and other products. The overall recycling rate of solid waste from electrolytic aluminum reaches 98%