Ceramsite obtained from water and wastewater sludge and its characteristics affected by (Fe(2)O(3)+CaO+MgO)/(SiO(2)+Al(2)O(3)).
To control and optimize the process for making ceramsite from wastewater treatment sludge (WWTS) and drinking-water treatment one (DWTS), the effect of mass ratios of (Fe(2)O(3)+CaO+MgO)/(SiO(2)+Al(2)O(3)) (defined as F/SA ratios); SiO(2):Al(2)O(3) and Fe(2)O(3):CaO:MgO (under the condition of fixed F/SA ratio) on the characteristics of ceramsite were investigated. It was found that the optimal F/SA ratios for making ceramsite range 0.175-0.45. Na-Ca feldspars and amorphous phases increase in ceramsite as F/SA ratios increase. Ceramsite with porous surfaces, expanded structures, and complex crystalline phases can be obtained at 0.275</=F/SA</=0.45, which accordingly cause the decrease in compressive strength. Higher strength of ceramsite with lower porosity can be obtained at 0.175</=F/SA<0.275, and under the condition of F/SA ratio=0.275, the raw materials can produce ceramsite with desired physical properties at 18.2:35</=SiO(2):Al(2)O(3)</=45:10.2 and 10:2.7:1.4</=Fe(2)O(3):CaO:MgO</=5.3:6:1.6. Ceramsite with higher compressive strength and lower porosity can be obtained at SiO(2):Al(2)O(3)>27.2:15.8 and Fe(2)O(3):CaO:MgO>6:3.5:1.8. Results indicate that F/SA ratios could be used as an important parameter to control the production process of ceramsite with desired physicochemical properties and resolve the disposal problems of residual sludges.
Xu
G R
GR
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China. xgr@hit.edu.cn
Zou
J L
JL
Li
G B
GB
D000537:Aluminum Oxide; D017610:Calcium Compounds; D003247:Conservation of Natural Resources; D003252:Construction Materials; D005290:Ferric Compounds; D008277:Magnesium Oxide; D008855:Microscopy, Electron, Scanning; D012722:Sewage / Q000737:chemistry*; D012822:Silicon Dioxide; D014867:Water / Q000737:chemistry*
D017610:Calcium Compounds; D005290:Ferric Compounds; D012722:Sewage; D014867:Water; D008277:Magnesium Oxide; D012822:Silicon Dioxide; D000537:Aluminum Oxide