Efficient Dewatering of Sludge from Recycled Lead Smelting Wastewater

During the process of recycled lead smelting and non-ferrous metal smelting, wet flue-gas scrubbing systems generate industrial wastewater containing high levels of suspended solids. Following neutralization with calcium oxide (CaO), heavy metal ions and other impurities in the wastewater precipitate, resulting in metallurgical sludge that requires further dewatering. This type of sludge typically contains calcium hydroxide, calcium sulfite, gypsum, calcium carbonate, fine furnace dust, and lead compounds such as PbO and PbSO₄; it is characterized by a complex composition and a high content of inorganic particles. Consequently, selecting an appropriate filter press for this metallurgical sludge is crucial for enhancing wastewater treatment efficiency and reducing sludge disposal costs.

Compared to typical industrial sludge, metallurgical wastewater sludge presents specific filtration challenges. With a solids content generally ranging from 10% to 15% and particle sizes primarily between 30 and 100 μm, the material can form a filter cake; however, the presence of fine metal-hydroxide precipitates increases filtration resistance and often leads to the clogging of filter cloths. Furthermore, the slurry is corrosive and prone to sedimentation, while gypsum and other calcium salts may form deposits within pipelines and machine. An improper choice of machine can easily result in issues such as restricted feed flow, reduced filtration efficiency, and the need for frequent maintenance. Therefore, when processing metallurgical wastewater sludge, it is essential to consider not only filtration capacity but also the machine's corrosion resistance, anti-clogging capabilities, and operational stability.

For this type of material, an automatic enclosed chamber filter press is highly suitable. The machine utilizes chamber-style filter plates to form a sealed filtration cavity. Under pressure supplied by a feed pump, solid particles in the sludge are retained to form a filter cake, effectively separating the liquid phase from the solid impurities. The enclosed design prevents the splashing of lead-containing filtrate and the escape of dust, thereby meeting safety and environmental requirements for the handling of hazardous waste. Features such as automatic plate shifting, automatic cake discharge, and PLC control systems help minimize manual intervention and improve overall operational efficiency. In terms of material configuration, filter plates can be made of stainless steel or reinforced polypropylene (PP), offering resistance to both corrosion and abrasive wear from solid particles. To address challenges such as fine particles and calcium salt deposits, an automatic filter cloth cleaning system can be integrated, which helps mitigate issues like filter cloth clogging and slurry sedimentation during the filtration process.

For projects involving the treatment of wastewater from secondary lead smelting, sludge from metallurgical flue-gas scrubbing, or other industrial wastewater containing heavy metals, automatic enclosed chamber filter presses provide an effective solution that combines sludge dewatering, centralized filtrate collection, and operational safety. By carefully selecting the appropriate filter cloth material, filtration pressure, and filtration area—supported by filtration tests tailored to the specific material—it is possible to enhance solid-liquid separation efficiency, reduce sludge volume, and lower costs associated with subsequent transport and disposal. This offers a stable and reliable solution for the management of sludge derived from metallurgical wastewater.