| 摘要 |
<p>PURPOSE:To provide a crystallized aggregate having excellent mechanical strength and chemical resistance by a method wherein a sewage sludge essentially consisting of SiO2, Al2O3, Fe2O3 and CaO and regulated to a specific range of composition is melted, and the obtained nucleus-forming product is heat-treated under a specific condition. CONSTITUTION:A sewage sludge having a main chemical composition of SiO2: 18-45wt%, Al2O3: 1-15wt%, Fe2O3; 1-35wt%, and CaO: 13-45wt% and the CaO/SiO2 ratio controlled to 0.6-1.3 is melted in a melting furnace. The molten product is kept at 850-950 deg.C for 15min or more to form crystallization nuclei. The obtained nucleus-forming product is crystallized by being kept at 1,050- 1,200 deg.C for 20min or more. This produces a high-strength crystallized aggregate.</p> |
