Research on limits of heavy metal contents in ceramsite blocks based on risk assessment

In order to control the environmental risk of heavy metals in the ceramsite used for building materials, samples of ceramsite blocks prepared by using ceramsite fired by electroplating sludge were collected, and the content of heavy metals, the toxic concentration of leaching and the effective amount of heavy metals in ceramsite blocks were analyzed. The characteristic heavy metals and their potential risks were ide.pngied, and a method based on the risk assessment method for determining the limits of heavy metals was established when ceramsite blocks were used. The method was used to calculate the limits of heavy metals in ceramsite blocks in two kinds of exposure scenarios, i.e. wall materials and pavement laying. The results showed that the characteristic heavy metals in the ceramsite blocks were Cr, Ni, Cu, Zn and Ba. The leaching (releasing) toxicity concentrations of these five heavy metals was 30.0-48.6, 37.2-132.0, 28.7-50.6, 12.9-169.0 and 609-674 μg/L, respectively. These values were lower than the standard limits in Ide.pngication Standard for Hazardous Wastes-Ide.pngication for Extraction Toxicity (GB 5085.3-2007). Therefore, the use of electroplating sludge to make ceramsite blocks was a feasible resource harmless treatment method. The maximum leaching(releasing) concentration of Cr, Ni, Cu, Zn, Ba from abandoned ceramsite blocks was 1.50, 0.20, 10.00, 10.00 and 7.00 mg/L, respectively. The limit content of Cr, Ni, Cu, Zn, Ba in ceramsite blocks was of 186 198, 3 313, 8 740, 36 703 and 3 272 mg/kg, respectively. The proposed method could provide basis for the environmental risk control of heavy metals in ceramsite and provide a reference for the method of formulating the content limits of heavy metals in building materials.