Department of Chemical Engineering and Inorganic Chemistry, University of Cantabria, Avda. Los Castros s/n, 39005 Santander, Spain.
J Environ Manage. 2011 Mar;92(3):994-1002. doi: 10.1016/j.jenvman.2010.11.004. Epub 2010 Dec 3.
The feasibility of recycling spent foundry sand in clay bricks was assessed in laboratory, pilot line and industrial trials, using naturally occurring sand as a reference. Raw materials were analyzed by X-ray fluorescence, X-ray diffraction, particle size distribution, and leaching and combined to produce bodies containing up to 35% wt. sand. The extrusion, drying and firing behaviour (plasticity, drying sensitivity, mechanical strength, bulk density, water absorption, and shrinkage) were determined. The microstructure, phase composition, durability and leaching (EN 12457, granular materials, end-life step, European Waste Landfill Directive; NEN 7345, monolithic materials, use-life step, Dutch Building Material Decree) were evaluated for bricks manufactured at optimal firing temperature. These results demonstrate that spent foundry sand can be recycled in clay bricks. There are no relevant technological drawbacks, but the feasibility strongly depends on the properties of the raw materials. Spent foundry sand may be introduced into bricks up to 30% wt. Most of the hazardous elements from the spent foundry sand are inertized during firing and the concentrations of hazardous components in the leachates are below the standard threshold for inert waste category landfill excepting for chromium and lead; however, their environmental risk during their use-life step can be considered negligible.
对回收铸造用废砂生产粘土砖的可行性进行了实验室、中试和工业试验研究，以天然砂为参照。用 X 射线荧光分析、X 射线衍射分析、粒度分布、浸出和综合方法对原材料进行了分析，并用其生产含砂量达 35wt%的制品。研究了挤出成型、干燥和烧成性能（塑性、干燥敏感性、力学强度、体密度、吸水率和收缩率）。对优化烧成温度下生产的砖进行了微观结构、物相组成、耐久性和浸出（EN 12457，粒状材料，最终使用寿命阶段，欧盟废物填埋指令；NEN 7345，整体材料，使用寿命阶段，荷兰建筑材料法令）评价。结果表明，铸造用废砂可以回收利用于粘土砖中。没有明显的技术缺陷，但可行性取决于原材料的性能。铸造用废砂的含量最高可达 30wt%。在烧成过程中，废砂中的大部分有害元素被惰性化，浸出液中有害成分的浓度低于惰性废物类别填埋的标准阈值，除铬和铅外；然而，在其使用寿命阶段，其环境风险可以认为是可以忽略的。
