Recently, the clean recycling process of "collaborative enrichment of flue ash - low-temperature melting - full element resource utilization" jointly developed by leading domestic recycled lead enterprises and research institutions has officially been industrialized. This process successfully solves the industry problem of heavy metal loss and severe secondary pollution in the lead flue ash recovery process. After testing by a third-party authoritative institution, the comprehensive lead recovery rate is as high as 99.2%, far exceeding the average level of traditional processes of 90% -95%. The entire process achieves harmless disposal of wastewater, exhaust gas, and waste residue, providing a new technological paradigm for the circular economy upgrade of the recycled lead industry.
Lead flue ash is a typical hazardous waste generated during processes such as metal smelting and recycling of waste lead-acid batteries, with an annual global output of over 2 million tons. This type of waste is rich in heavy metals such as lead and arsenic. If not disposed of properly, 1 gram of lead can contaminate 1 cubic meter of water to exceed the standard by 20 times. It can also harm the ecological environment and human health through soil infiltration, food chain enrichment, and other pathways. Traditional recycling processes often use high-temperature pyrometallurgical melting, which not only requires a high temperature environment of over 1300 ℃ and high energy consumption, but also has problems such as high smoke and dust rates, serious lead loss, and large fluctuations in sulfur dioxide concentration in the generated flue gas, making it difficult to effectively treat and posing a prominent risk of secondary pollution. The clean recycling process implemented this time has achieved full process innovation through the integration of multiple technologies.
In terms of breakthroughs in core technology, this process has established a "three-level collaborative processing" system to improve recycling efficiency and environmental protection level from the source. Firstly, X-ray fluorescence (XRF) and AI image recognition intelligent sorting system are used to accurately preprocess flue ash, achieving efficient separation of impurities such as lead, copper, and tin with a sorting accuracy of ± 0.5%, laying the foundation for subsequent recovery. Subsequently, the innovative application of the "iron silicon calcium sodium" quaternary low melting point slag system lowered the melting temperature from above 1300 ℃ in traditional processes to below 1150 ℃, reducing the comprehensive energy consumption of a single ton of product by 30%. At the same time, it was equipped with a new type of oxygen enriched side blowing furnace. Through the high-density layout design of low stirring load oxygen guns, the smoke and dust rate was reduced to below 14%, and the vertical yield exceeded 98%. Finally, through the use of an ionic liquid assisted acid production system, the concentration of sulfur dioxide in the flue gas was stably controlled at around 3%, achieving efficient acid recovery and completely solving the pain point of difficult sulfur dioxide treatment in traditional processes.
The whole process environmental control is another highlight of this technology, truly achieving the goal of "no secondary pollution". In terms of exhaust gas treatment, a "bag dust removal+wet electric collaborative purification" system is adopted to perform multi-stage treatment on the smelting flue gas. The final emission of particulate matter concentration is less than 10mg/Nm ³, and the emissions of sulfur dioxide and nitrogen oxides are controlled below 100mg/Nm ³, far exceeding the requirements of the "Emission Standards for Industrial Pollutants of Recycled Copper, Aluminum, Lead, and Zinc". In the wastewater treatment process, the heavy metal containing wastewater generated during the production process is purified by a dedicated treatment system and fully recycled without being discharged, achieving a water resource utilization rate of 100%. In terms of waste disposal, the tailings generated from smelting are treated with water quenching to form glass bodies with a lead content of less than 1%. They belong to general industrial solid waste and can be directly sold for cement production, with a resource utilization rate of 99.8%; The lead containing waste residue generated during the refining process is returned to the smelting system for recycling, achieving a closed-loop of resources throughout the entire process.
At present, the process has been put into stable operation in the annual production of 200000 tons of recycled lead project, with a cumulative processing capacity of over 150000 tons of lead flue ash and the recovery of 148000 tons of high-purity lead ingots, creating direct economic benefits of over 2.3 billion yuan. The purity of the produced lead ingots reaches 99.99%, fully complying with the standard of "Regenerated Lead and Lead Alloy Ingots" (GB/T 21181-2017), and can be widely used in high-end fields such as new energy storage batteries and nuclear power protection. Industry experts say that the large-scale application of this process can not only significantly improve the recycling and utilization rate of lead resources, but also significantly reduce the industry's carbon emission intensity. It is expected that a single plant will reduce carbon dioxide emissions by more than 500 tons per year, providing key technical support for China to achieve the planning goal of "lead regeneration rate of over 70% by 2025".
With the continuous promotion of clean recycling technology, the recycled lead industry is transforming from "end of pipe treatment" to "full value utilization of resources". In the future, it will further promote industry concentration and green low-carbon development, providing more environmentally friendly and efficient raw material guarantees for fields such as new energy and nuclear industry.
