The Environmental Protection Administration officially designated waste lead-acid batteries as recyclable waste in the year 1989. In recent years, the annual collection of lead batteries in Taiwan has reached 50,000 to 70,000 metric tons. Currently, the common method for recycling waste lead-acid batteries in Taiwan involves the pyrometallurgical process to recover lead metal. However, similar to general secondary metal smelters, the issue of final disposal of the resulting furnace slag presents a challenge. Furthermore, lead is classified as one of the hazardous industrial waste materials, leading to the predominant disposal method of solidification followed by landfilling. In recent years, as landfills gradually reach saturation, the associated disposal costs have been on the rise. This project explores the feasibility of using derived lead slag as a substitute for some of the raw materials in red brick manufacturing. Observing the results of toxicity leaching experiments conducted in the laboratory, the Pb leaching value in lead slag reaches as high as 417 mg/L. In contrast, the Pb leaching values for various red brick specimens range from only about 0.06 to 0.35 mg/L. For red bricks manufactured in the factory, the Pb leaching value is 0.13 mg/L, meeting the recycling material standard of 0.3 mg/L. This indicates that through the sintering process of red bricks, Pb elements have been solidified within the clay matrix of the aluminum-silicon crystal lattice, resulting in a relatively lower risk of leaching. In the compressive strength and water absorption tests for red bricks with addition levels of 1%, 2.5%, 5%, and 10%, both water absorption and compressive strength met the specifications for the third category of bricks. In the case of factory-produced bricks, compressive strength also met the third-category specifications, although water absorption was slightly higher than the standard. This difference is attributed to manual brick preparation in the laboratory. However, it is anticipated that using professional brick-making equipment in a factory setting would enable compliance with the standard requirements. Therefore, based on the laboratory trial results, the optimal ratio for the addition level was determined to be 1%. In the estimation of Pb loss and volatilization, the primary loss stage for Pb occurs in the temperature range of 800°C to 850°C. Subsequent increases in temperature and time show minimal changes in the loss variation. After calculating the estimated Pb volatilization, the volatile proportion is found to be 19.83%, indicating that materials with higher Pb content still impact exhaust emissions. Therefore, when producing red bricks containing lead slag, attention should be paid to the blending ratio. It is recommended that, if there is a desire to enhance processing capacity, consideration should be given to increasing pollution control measures at the backend to improve overall processing capabilities.

Lead-containing furnace slag, Heavy metals, Bricks