機械研磨飛灰-高嶺土不僅將粉體粒徑減小，且使粉體達到無晶序化(amorphization)，粉體的無晶序化和燒結後鈣長石相對含量具正相關；而以焚化飛灰作為合成鈣長石的鈣源，經研磨粉體燒製後，可觀察到眾多短柱狀的鈣長石結晶，成功製備出鈣長石基陶瓷材料，並將燒製的溫度從1,300 ℃降至950 ℃，經燒製後的產品，重金屬溶出已經非常低，產品已無害化。
In Taiwan, incineration had become the major method to treat the municipal solid waste. Incineration has the advantages of good volume and mess reduction efficiency and healthy, but the residual fly ash was classified as hazardous waste since it contained much heavy metals, which could not pass the TCLP test, and should be solidified before landfilling. Nevertheless, the landfill site is difficult to be installed, and the long-term stability of the heavy metals of the solidified matrix was doubted by the publics. Therefore, to develop new detoxification and recovery technologies for fly ash are urgently.
This study introduced the concept of mechanochemical reactions, which provided mechanical energy to promote the characteristics change of the heavy metals in the fly ash to reach the aim of stability. In this study, the high energy ball milling was used to reduce the milling time. The optimum operation conditions for wet milling were studied, and then to explore the stabilization mechanism of lead. Furthermore, milled fly ash powder was blended with aluminum silicate rich kaolin, and sintered to produce humidity-controlling ceramic as the ecological building material. On the other hand, the soft mechanochemical synthesis mechanism was applied in the anorthite-based ceramic production with fly ash blended with kaolin, due to the rich calcium-based property of fly ash.
The results showed that, 8 hours milling can reach the effect of 96 hours traditional wet ball milling for lead stabilization. Lead in the high pH could react with chloride ions to generate Pb7O6Cl2 precipitation, after milling, the much stable species PbO2 and Pb2O3 will produced. The results of the mathematical relationship analysis for weight factors of lead stabilization showed that, the highest weight factors is milled ash, 92.44 %; but the lowest is lead chloride salt which weight factor, which is negative, and it will affect the other stability effects.
The humidity-controlling ceramic produced from mixed powder milled 8 hours and then sintered at 1,000 oC performed 70 % moisture absorption ability, which can meet the grade 3 standard in Japan. It was found that the intensity of the diffraction peaks of mayenite (Ca12Al14O33, C12A7) of sintered sample is proportional to the amount of moisture absorption and desorption, while calcium aluminum (Ca2Al2SiO7, C2AS) is inversely proportional. Therefore, the mayenite generated in sintered specimen is helpful to moisture absorption and desorption.
Mechanical milling of the fly ash with kaolin not only decreases particle size, but also transforms the crystals into amorphization. Furthermore, the amorphization of the powder and relative content of anorthite after sintering process have a positive correlation. Using fly ash as a calcium source to synthesize anorthite by milling and sintering could observe many short columnar crystals of anorthite. The process of milling and sintering can successfully prepare anorthite-based ceramic materials and could decrease the sintering temperature from 1,300 oC to 950 oC. The leaching of heavy metals of the product is very low and it has been harmlessly.