| 摘要: | 造紙廠使用循環式流體化床鍋爐所產出之固體再生燃料（Solid Recovered Fuel, SRF）混燒飛灰可達成廢棄物資源再利用的目標，但部分SRF混燒飛灰在後端處理時存在以下問題：(1)再利用產品之品質不穩定，(2)部分水泥產品發生體積膨脹與開裂。因此，本研究針對與水泥拌和後具有膨脹趨勢之SRF混燒飛灰(J廠與C廠飛灰)，並進行相關之預處理試驗，最終對其成效提出初步評估，提供再利用途徑之判斷依據。
由兩鍋爐廠取樣試驗結果發現，混燒飛灰與水泥拌和產生的體積膨脹發生在試體硬固之前，因燃料中不完全燃燒之的金屬鋁所致，會在水泥新拌階段產生大量氫氣並使試體膨脹及開裂。使用氣體容積法建立產氣轉換式以推估兩廠混燒飛灰中的金屬鋁含量，並採用未處理及預處理等方式進行再利用的合適性評估。未處理部分進行CLSM試驗，預處理部分則包括水浸泡處理、熱處理、鹼浸泡處理、鹼激發處理，其中，鹼激發處理使用水淬爐石粉作為膠結材，而其餘處理的膠結材則是卜特蘭水泥。
試驗結果顯示，具膨脹性的混燒飛灰在未處理之情況下製作成CLSM是無效的；水浸泡處理的效果亦有限，因試體膨脹的現象無法被完全去除；熱處理的結果表示，950℃的處理溫度效果優於750℃，除了能解決體積膨脹問題，也可提高飛灰試體之抗壓強度；鹼浸泡處理可解決膨脹問題，但混燒飛灰試體之抗壓強度明顯下降；鹼激發處理使試體不再膨脹，然而對高鋁含量飛灰的處理效果不佳，抗壓強度改善有限，甚至在低藥劑濃度時引發嚴重的緩凝問題。另廠低鋁含量混燒飛灰的鹼激發處理效果顯著，不同鹼藥劑用量下之抗壓強度大幅提升，在混燒飛灰使用量高達50 %情況下，試體抗壓強度可達到卜特蘭水泥的強度標準。
;Solid Recovered Fuel (SRF) co-firing fly ash which is produced by paper mills by using Circulating Fluidized Bed (CFB) have achieved the goal of waste recycling. However, some of SRF co-firing fly ash encounter the problems while back-end processing: (1) The instability of recycled products quality, (2) some cement products occurs expansion and cracking reactions. Therefore, this study aimed at the SRF co-firing fly ash (SRF-J and SRF-C) which have expansion tendency while mixing with cement, and carried out relevant pretreatment tests to provided a preliminary evaluation, offering the basis of judgement on the way of co-firing fly ash reuse.
In the initial results of study found that the expansion only occurred before hardened when co-firing fly ash maxing with cement, this phenomenon caused by the incomplete combustion of metallic aluminum in the CFB, a large amount of hydrogen will be generate when metal aluminum mixing with cement, and leads to expansion and cracks on specimen.
In addition, the gas release test was used establish a gas emission conversion function to estimate the metallic aluminum content in both of co-firing fly ash, and adopt un-treatment and pre-treatment to evaluate the potential of co-firing fly ash reuse. Un-treatment part select Controlled Low Strength Material (CLSM) test , and the pre-treatment part included water treatment, heat treatment, alkali solution treatment, and alkali-
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activated treatment. Among them, the alkali-activated treatment use slag blender material, and the other treatment use cement.
The test results show that it is invalid to make a sample as CLSM without treatment; the effect of water treatment is limited, cause the phenomenon of the specimen expansion cannot be completely removed; In heat treatment test found that treatment temperature 950℃℃is better than 750℃℃, 950℃℃can remove metallic aluminum in both of fly ash sample, and increase compressive strength of cement mortar; alkali treatment solves the expansion problem, but significantly lower both of fly ash sample’s compressive strength; Alkali-activated treatment also improve expansion problem, however, it do not improve the performance in high metallic aluminum content of fly ash, limited improvement in compressive strength of mortar, and even cause serious slow-setting in low concentration of alkali condition. The performance in low metallic aluminum content of fly ash can be improve significantly with alkali-activated treatment, the compressive strength under different alkali concentration, the strength can still be maintained at an acceptable level (higher than 40 MPa)When the fly ash content is as high as 50%. |
