焚化飛灰以微波消化處理鉛重金屬溶出削減特性之研究

Dynamic Characteristic of Reduction of Lead Metal Leaching from Flyash of Incineration by Microwave Digestion

謝宗甫(Fu-Zong Xie)

指導教授 ： 章裕民

國立臺北科技大學/工程學院/環境規劃與管理研究所/碩士(2007年)

摘要

焚化飛灰中鉛、鎘重金屬濃度常超出法規之毒性溶出管制標準，致使對後續處理及資源化應用產生諸多限制。本研究針對北部某大型焚化廠進行一年為期12個月之焚化灰渣採樣，以建立民國95年焚化飛灰之基線資料。

本研究之目的為探討利用微波輔助酸消化法對於焚化飛灰進行消化反應時之反應動力學。將飛灰進行粒徑分析，樣品分為dp>417µm、295µm< dp<417、74µm< dp<295µm及37µm< dp<74µm四組，在微波功率600W、消化液濃度9M、固液比1/10下進行不同消化時間與溫度之多次實驗，並配合TCLP進行溶出量推估，四種粒徑之飛灰經由不同消化時間與溫度之微波消化後，推求其TCLP溶出削減量之速率式。由實驗結果發現，焚化飛灰在消化溫度160℃之條件下，消化時間16分鐘時經微波消化處理（MDT）後其各組粒徑之飛灰TCLP削減率高達90％以上，且飛灰粒徑對於重金屬鉛之TCLP削減量影響較顯著。

利用線性迴歸方式建立各組飛灰消化溫度與消化反應速率常數之關係，研究發現dp>417µm、295µm< dp<417、74µm< dp<295µm及37µm< dp<74µm四組粒徑範圍下其微波消化之表觀活化能各約為7.6(Kcal/mole)、11.9(Kcal/mole)、20.2(Kcal/mole)及32.6(Kcal/mole)，發現反應灰之粒徑為影響反應活化能之重要指標，當飛灰顆粒愈小時，由於飛灰顆粒表面外膜阻力以及孔擴散阻力，而限制擴散效應進行，因而降低了整體微波消化處理速率。

關鍵字

微波消化處理（MDT） ； 焚化飛灰 ； 鉛重金屬 ； 削减動力學

並列摘要

In general TCLP concentrations of Lead and Cadmium in flyash are usually over the regulation standards. It results in many restrictions on treatment and recycling. Flyash emitted from a large-scale refuse incinerator in the north Taiwan was investigated in this study.

The objective of this research is discuss the dynamic of TCLP reduction, lead metal in flyash by Microwave Digestion Treatment method. Samples of flyash were divided into four groups, dp>417µm、295µm< dp<417、74µm< dp<295µm及37µm< dp<74µm. The experiments follow-up on the conductions, 600W, digested liquid 9M, liquid-solid ratio 1/10 and on the different digestion time and temperature to find out the rate of TCLP reduction. Result reveal after MDT ,the rate of TCLP reduction in lead metal up to more than 90％ at digestion temperature 160℃ and digestion time 16 minutes. On the other hand, the diameter of particle affect the TCLP reduction in lead metal more seriously.

Useing the linear regression to published the relationship between digestion time and rate constant of digestion in every group of diameter of particle, it was found that the appearance activation energy of every group of flyash （dp>417µm、295µm< dp<417、74µm< dp<295µm及37µm< dp<74µm）is 7.6(Kcal/mole)、11.9(Kcal/mole) 、20.2(Kcal/mole) and 32.6(Kcal/mole). The experimental results indicate that the diameter of particle is an important factor on the TCLP reduction rate in lead metal. When the flyash diameter of particle became smaller, the diffusion between acid molecule and particle of flyash will be limited because of the outer layer and inner part layer drag of flyash particles . Therefore the rate of microwave digestion treatment and TCLP reduction in lead metal would be reduced.

並列關鍵字

Microwave digestion treatment ； Flyash ； Lead metal ； Prevention efficiency

參考文獻

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