Building Technology and Construction Management Division, Department of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
Waste Manag. 2010 Aug-Sep;30(8-9):1528-35. doi: 10.1016/j.wasman.2010.03.027. Epub 2010 Apr 18.
Coal combustion residues which include fly ash, bottom ash and boiler slag is one of the major pollutants as these residues require large land area for their disposal. Among these residues, utilization of bottom ash in the construction industry is very low. This paper explains the use of bottom ash through pelletization. Raw bottom ash could not be pelletized as such due to its coarseness. Though pulverized bottom ash could be pelletized, the pelletization efficiency was low, and the aggregates were too weak to withstand the handling stresses. To improve the pelletization efficiency, different clay and cementitious binders were used with bottom ash. The influence of different factors and their interaction effects were studied on the duration of pelletization process and the pelletization efficiency through fractional factorial design. Addition of binders facilitated conversion of low-calcium bottom ash into aggregates. To achieve maximum pelletization efficiency, the binder content and moisture requirements vary with type of binder. Addition of Ca(OH)(2) improved the (i) pelletization efficiency, (ii) reduced the duration of pelletization process from an average of 14-7 min, and (iii) reduced the binder dosage for a given pelletization efficiency. For aggregate with clay binders and cementitious binder, Ca(OH)(2) and binder dosage have significant effect in reducing the duration of pelletization process.
燃煤残渣（包括粉煤灰、底灰和炉渣）是主要污染物之一，因为这些残渣需要大量土地进行处理。在这些残渣中，底灰在建筑行业中的利用率非常低。本文介绍了通过颗粒化利用底灰。由于底灰的粗糙性，原始底灰不能直接颗粒化。虽然细磨底灰可以颗粒化，但颗粒化效率较低，且骨料强度太弱，无法承受处理过程中的应力。为了提高颗粒化效率，使用了不同的粘土和胶凝粘结剂与底灰混合。通过部分因子设计研究了不同因素及其交互作用对颗粒化过程持续时间和颗粒化效率的影响。粘结剂的添加促进了低钙底灰向骨料的转化。为了达到最大的颗粒化效率，粘结剂的含量和水分要求随粘结剂的类型而变化。添加 Ca(OH)(2) 提高了（i）颗粒化效率，（ii）将颗粒化过程的持续时间从平均 14-7 分钟缩短，（iii）减少了给定颗粒化效率所需的粘结剂用量。对于含有粘土粘结剂和胶凝粘结剂的骨料，Ca(OH)(2)和粘结剂用量对缩短颗粒化过程的持续时间有显著影响。
