The amended techniques effect on refractory material corrosion and metals emission in melting of Municipal Solid Waste Incinerator fly ash

• Main Authors: Yu-hsin Hu, 胡友馨
• Other Authors: Kung-yuh, Chiang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/09218776520729939976

碩士 === 逢甲大學 === 環境工程與科學所 === 95 === This study investigated that washing and additive effects on the metals emission resuction and refractory material corrosion in melting of municipal solid waste incinerator (MSWI) fly ash by water-washing and waste glass addition. Experimental conditions were including the liquid-to-solid (L/S) 10, 20, 50, 100 for water-washing treatment and waste glass addition ratio ranging from 10% to 90%. Meanwhile, the fly ashes after washing or waste glass addition pretreatment were conducted at 1450℃ for 2hrs. The basicity of tested fly ash was decreased from 22.1 (?) to 4.61 and 0.09, respectively. Experimental results indicated that the extraction efficiency of Pb increased with L/S ratio increased by water washing. The maximum extraction efficiency was 78.00% at L/S 100. However, the extraction efficiencies of Cu, Zn, Cr, and Cd were increased insignificantly with L/S ratio increased. Soluble salts, Na+、K+、Cl- and SO42- , approximately 94.12%-99.73% were extracted by water washing at all of tested L/S ratio. In case of L/S 100, the extraction efficiencies of Ca2+ and Mg2+ were 78.25% and 0.65%, respectively. According to XRD analysis results, the mineral species in fly ash were metal silicates (Zn2SiO4 and Al2SiO5) and metal sulfides (ZnS). Based on the above-mentioned results, the change of species in fly ash would improve the metals emission reduction and the refractory materials corrosion in melting. According to the results of metals emission in tested fly ash melting, the partitioning in molten slag of Cu, Cr, Al, Ca and Mg were ranging from 58.56% to 99% in washed fly ash melting. The partitioning of above metals increased with L/S increased. Zn, Cd, Pb, Na, K, Cl- and SO42- were mainly presented in gas phase, the percentage of partitioning was above 90%. This is due to the physical and chemical characteristics of metals or tested elements in melting. According to the results of waste glass addition, Cr, Cd, Al, Ca and Mg were remained in molten slag, and the percentage of partitioning increased with glass addition increased. Some metals, such as Zn, Pb, Cu, Na, K, Cl- and SO42- still partitioned to gas phase. Although, in this study, there were less effect on the emission reduction of some tested metals or elements by water washing and glass addition, it would be good for reduction of the quantities of total metal emission. In case of MSWI fly ash melting, the corrosion depth of refractory material was 7144μm and 100% penetration. According to the results of corrosion test, the penetration depth of washing ash was in the range of 7505μm~8237μm as L/S 10~50. When the L/S ratio 100, the corrosion depth was about 6568 μm. There was show that corrosion depth decreased with glass addition increased. When fly ash mixed with 10%~90% glass addition, its corrosion depth decreased from 7388 μm to 4946μm. These results showed that glass addition could inhibit the refractory materials corrosion in fly ash melting. In addition, the penetration distribution of Ca and Mg in refractory materials was inhibited as 20%-90% glass addition. Cl and S also showed the inhibitory effect in refractory materials, especially the 90% glass mixture ash. It can concluded that the change of physical and chemical characteristics of fly ash by water washing and waste glass addition, and improvement of the refractory materials corrosion. It also would be good for the application of refractory materials in melting furnace.