Extraction of metals from municipal solid waste incinerator fly ash by hydrothermal process.
This work examined the extraction properties of metallic elements from municipal incinerator fly ash under hydrothermal conditions. The ash was firstly pre-washed by distilled water, then subjected to hydrothermal treatments. The pre-washing process was effective for Na, K, Ca extraction with extraction percentages of 67%, 76% and 48%, respectively. The optimum contact time was 30 min for the pre-washing process. Five types of acids were tested for the extraction experiments and hydrochloric acid was found to be most effective for metal extraction from the ash. Compared to room condition, hydrothermal treatment accelerated the dissolution of the ash, thus promoted the reaction of acid with hazardous metals such as Cr, Cd, Pb, and furthermore, the consumption speed of acid was slowed down under hydrothermal condition. The acid simultaneously reacted with all the metal in the ash under hydrothermal condition but preferentially reacted with Ca at room condition. The optimum hydrothermal treatment temperature, time and liquid/solid ratio were 150 degrees C, 5h and 10:1 (ml:g), respectively.
Zhang
Fu-Shen
FS
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18, Shuangqing Road, Beijing 100085, China. fszhang@rcees.ac.cn
Itoh
Hideaki
H
D002244:Carbon / Q000032:analysis*; D060729:Coal Ash; D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D008670:Metals / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011786:Quality Control; D012037:Refuse Disposal; D015203:Reproducibility of Results; D012995:Solubility; D013696:Temperature; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D060729:Coal Ash; D008670:Metals; D052638:Particulate Matter; D014867:Water; D002244:Carbon