As one of the world’s major aluminum producers, China’s booming electrolytic aluminum and aluminum alloy smelting industries face severe challenges in solid waste disposal. Aluminum and aluminum alloy smelting processes inevitably generate byproducts such as aluminum dross and slag. Notably, aluminum dross is explicitly listed in the National Hazardous Waste Catalogue (2021 Edition), becoming a critical bottleneck restricting the industry’s green development.

During the overhaul of electrolytic cells after 4–5 years of service, electrolytic aluminum enterprises produce large volumes of overhaul slag. Currently, only a small portion of refractory materials can be recycled, with most waste disposed of via landfilling or open-air stockpiling. This practice not only occupies valuable land resources but also poses long-term ecological risks: cyanide and fluoride compounds in the slag seep into soil and contaminate water bodies, subjecting enterprises to stringent environmental compliance pressures and high costs. Resolving the disposal challenges of aluminum dross and overhaul slag to achieve reduction, harmless treatment, and resource recovery is both an inevitable requirement for national environmental strategies and a must for high-quality development in the aluminum industry.

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With over 60 years of expertise in equipment manufacturing, Henan Zhengzhou Mining Machinery Co., Ltd. (ZKM) leverages technological innovation and its full-industry-chain capabilities to address the pain points of hazardous waste disposal in the aluminum sector. The company has developed an integrated solution for the collaborative utilization of aluminum dross and overhaul slag. Adopting the innovative philosophy of "treating waste with waste, turning slag into treasure", ZKM has created an efficient, high-value green pathway for hazardous waste disposal, empowering the aluminum industry’s green transformation with cutting-edge technology.

As a high-tech enterprise integrating scientific research, design, manufacturing, installation, commissioning, and operation support, ZKM boasts profound technical expertise and robust R&D capabilities. The company’s production base spans over 80,000 square meters, equipped with more than 300 sets of heavy-duty manufacturing equipment, including dedicated process workshops and analytical testing centers. These facilities enable pilot-scale trials and data analysis for solid and hazardous waste treatment, providing strong technical support for project implementation. ZKM’s R&D team, composed of professionals from bachelor’s to doctoral levels, has decades of experience in solid and hazardous waste disposal. The team accurately identifies industry needs, overcomes key technical barriers, and builds a complete industrial chain covering standalone equipment, turnkey EPC projects, and full-process services. With reliable product quality and comprehensive service systems, ZKM’s products are exported to over 100 countries and regions worldwide, earning high recognition from domestic and international clients.

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To tackle the disposal challenges of aluminum dross and overhaul slag, ZKM innovatively applies a "collaborative sintering of overhaul slag and aluminum dross for refining slag production" process. By harnessing the calorific value of cathode carbon blocks in overhaul slag and synergizing with aluminum dross and slag, this technology completely eliminates hazardous waste pollution while enabling efficient resource recovery, delivering multiple benefits. The entire process is scientifically rigorous, efficient, and controllable, with every step optimized to ensure compliance in both waste treatment and product quality:

01 Precision Pretreatment: Laying the Foundation for Resource Recovery

Multi-stage crushing, screening, and ball milling technologies are used to process aluminum dross/slag and overhaul slag into 80+ mesh aluminum dross powder and cathode powder, significantly enhancing material reactivity. Limestone is crushed into 5–30mm particles to improve performance, forming a solid basis for subsequent mixed material preparation. ZKM’s self-developed crushing and ball milling equipment delivers stable operation and high processing efficiency, with flexible capacity adaptation to meet client production requirements and ensure smooth pretreatment.

02 Intelligent Batching & Mixing: Ensuring Reaction Efficiency

A dedicated batching system precisely proportions and uniformly mixes pretreated aluminum dross powder, cathode powder, and crushed limestone into 100+ mesh mixed material. The system enables accurate ratio control, achieving a hazardous substance solidification rate of over 99%, ensuring harmless treatment during high-temperature calcination and maximizing resource recovery efficiency.

03 High-Temperature Calcination & Reconstruction: Turning Hazardous Waste into Resources

The mixed material is fed into ZKM’s self-developed high-temperature rotary kiln for calcination at a precise 1250°C. Materials move from the kiln tail to the head, passing through preheating, calcination, and cooling zones to complete detoxification, melting, and solidification, ultimately producing high-quality steelmaking refining slag. Notably, cathode carbon blocks in overhaul slag supply 60% of the kiln’s required heat, significantly reducing natural gas consumption. During calcination, cyanide decomposition exceeds 99.9%, while fluorides are stabilized as fluorite, with leaching toxicity far below national standards—achieving complete harmless treatment.

This collaborative utilization technology not only resolves the environmental challenges of aluminum dross and overhaul slag disposal but also enables high-value resource recovery:

Recovered aluminum is reused in aluminum smelting, reducing pressure on primary aluminum ore extraction.

The produced refining slag meets quality standards for Al₂O₃, CaO, and trace elements. When used in steel mills, it shortens refining time by 20% and reduces steel consumption by 8kg per ton, delivering substantial economic benefits.

Compared with traditional landfilling and stockpiling, ZKM’s solution transforms enterprises from passive pollution controllers to active value creators, unifying environmental, economic, and social benefits.

With decades of industry experience and an unwavering commitment to green development, ZKM adheres to the quality policy of "survive by quality, develop by technology" and the core culture of "ethics before profit, benefit after others". The company holds ISO 14001 (environmental management) and ISO 9001 (quality management) certifications, and has been awarded titles such as High-Tech Enterprise of Henan Province. Beyond continuous technology and equipment optimization, ZKM provides customized, one-stop full-process services—from site planning and process design to equipment manufacturing, installation, commissioning, and after-sales maintenance. This ensures rapid project implementation and efficient operation, helping clients reduce compliance costs and enhance core competitiveness.

As China advances its "dual carbon" strategy and tightens environmental regulations, the aluminum industry enters a critical phase of green transformation. ZKM will continue to drive innovation, deepen expertise in aluminum dross and overhaul slag comprehensive utilization, optimize processes and equipment, and deliver tailored solutions with reliable quality and attentive service. Together with aluminum enterprises, we will address hazardous waste challenges, promote resource recycling, and build a sustainable future for the aluminum industry.