In the shadow of China’s booming aluminum industry, a hidden environmental challenge is brewing. Every year, over 3 million tons of secondary aluminum dross, a hazardous byproduct of aluminum production, is generated. This figure is set to rise as recycled aluminum becomes more prevalent. But what if this waste could be transformed into a valuable resource, rather than a mounting problem? This is the question that Kun Lin, a researcher at the School of Minerals Processing and Bioengineering, Central South University in Changsha, China, is tackling head-on.
Secondary aluminum dross, a mixture of aluminum nitride, chlorine salts, fluoride, and about 40% aluminum, is a double-edged sword. It’s a hazardous waste that poses environmental risks, but it’s also a potential goldmine of aluminum resources. “The disposal of secondary aluminum dross has become a bottleneck restricting the development of the aluminum industry,” Lin notes.
Lin’s recent study, published in the Journal of Engineering Sciences, delves into the complex world of secondary aluminum dross, exploring its characteristics and the latest research on its detoxification and utilization. The findings reveal two primary methods for dealing with this waste: pyrometallurgical and hydrometallurgical processes.
The pyrometallurgical process, which involves high-temperature treatment, is currently the go-to method for large-scale utilization. It transforms dross into useful products like cement, refractory materials, and ceramic heat storage balls. However, it’s not without its drawbacks. The process is energy-intensive, can cause significant equipment corrosion, and is restrictive in terms of raw material composition.
On the other hand, the hydrometallurgical process, which uses water or chemical solutions to extract metals, offers a more environmentally friendly approach. It’s particularly effective at detoxifying high-salt dross, but it’s not without its challenges. The process generates a significant amount of waste liquid and may not completely remove aluminum nitride.
Lin’s research suggests a two-pronged approach to maximize the benefits of secondary aluminum dross. “Low-salt secondary aluminum dross can be directly discarded via the pyrometallurgical process. High-salt secondary aluminum dross can be pretreated via the hydrometallurgical process to remove salts and most of the nitrogen, after which the pyrometallurgical process can be employed to realize high utilization of the dross,” Lin recommends.
The potential commercial impacts of this research are vast. Efficient detoxification and large-scale, high-value utilization of secondary aluminum dross could not only eliminate environmental risks but also maximize the use of aluminum resources. This is crucial for the ecological environment and the healthy development of the aluminum industry, especially in the energy sector, where aluminum is a key material.
The future of secondary aluminum dross disposal lies in a more nuanced approach, one that considers the salt content and categorizes the dross accordingly. It’s a challenge, but one that Lin and her team are ready to tackle. Their work, published in ‘Journal of Engineering Sciences’, is a significant step towards a more sustainable and profitable aluminum industry.
