Lanzhou University's General Environmental Engineering Team (GEE Team), based on its proprietary cloud-based dust removal technology, has achieved a technological breakthrough in the flue gas treatment project for a 33,000 m³/h lead-zinc sintering cooling cylinder at Baiyin Nonferrous Metals Group. The team successfully solved the technical challenge of efficiently collecting submicron particles in the lead-zinc sintering process.

In pyrometallurgical processes, substantial flue gas containing submicron particles is generated during the cooling of lead-zinc sulfide concentrates after sintering in cooling cylinders. This flue gas has the following characteristics: 1）High temperature, with flue gas temperatures exceeding 1000℃; 2）Complex composition, containing heavy metals such as lead, zinc, and copper, with particulates primarily composed of zinc oxide, zinc sulfide, and lead oxide; 3）High soluble salt content, with soluble salts crystallizing in pipelines, further increasing the concentration of particles in the flue gas; 4）Small particle size, with a median particle diameter of less than 10 μm. The high temperature, complex composition, and fine particle size of the sintering cooling cylinder flue gas make it extremely difficult to achieve long-term, stable compliance with emission standards.

To address this issue, Lanzhou University's GEE Team fully leveraged the advantages of its platforms, including the "Gansu Provincial Industrial Flue Gas Treatment Technology Center" and the "Gansu Provincial Engineering Research Center for Fine Particulate Pollution Control Technologies and Equipment." Based on cloud-based technology, the team carried out a six-month technical campaign. Using Computational Fluid Dynamics (CFD) simulations (Figure 1), the team accurately calculated the water vapor saturation required for fine particle condensation in the sintering cooling cylinder flue gas. Various atomization methods were tested to construct supersaturated water vapor environments at different gas temperatures. After multiple iterations of "numerical simulation—laboratory testing—field trials," the team ultimately developed a novel process specifically for sintering cooling flue gas treatment: Heterogeneous Coalescence Enhanced Fine Particle Removal Technology (Figure 2).

The core of this process involves a "cloud mist generator," which rapidly cools the flue gas, increases water vapor humidity, and raises the saturation vapor pressure, thereby promoting particle nucleation and growth. This enables efficient removal of particles, metal elements, and soluble salts from the flue gas.

Fig.1 Schematic Diagram of the "Cloud-Based" Dust Removal Technology

Fig.2 Schematic Diagram of the "Cloud-Based" Dust Removal Technology

In mid-October 2024, Baiyin Nonferrous Group’s Third Smelting Plant organized an expert evaluation of the project. The expert team unanimously concluded that the cloud-based dust removal system fully met the technical standards. Dust removal efficiency exceeded 99%, and outlet concentrations achieved the latest ultra-low emission standard of less than 10 mg/m³, successfully passing on-site acceptance.

Fig.3 On-Site Photo of the Cloud-Based Dust Removal Equipment

The implementation of the lead-zinc sulfide concentrate sintering cooling cylinder flue gas dust removal project marks a further milestone in the GEE Team's innovations in flue gas treatment for the metallurgical industry. Moving forward, the GEE Team will continue to delve into technological innovation, align closely with industry frontiers, adhere to the "Four Orientations," and solve engineering and technical challenges in the industry, contributing Lanzhou University's strength to the nation’s ongoing efforts to secure blue skies.