Treatment and resource recovery from inorganic fluoride-containing waste produced by the pesticide industry
Yang Li , Hua Zhang
,
Zhiqi Zhang
,
Liming Shao
,
Pinjing He
DOI:10.1016/j.jes.2014.10.016
Received August 04, 2014,Revised October 16, 2014, Accepted , Available online May 19, 2015
Volume 27,2015,Pages 21-29
The rapid development of the fluorinated pesticide industry has produced a large amount of fluorine-containing hazardous waste, especially inorganic fluoride-containing waste (IFCW). A two-step process, including extraction and recovery, was developed to recover fluorine as synthetic cryolite from IFCW produced by the pesticide industry. The optimum conditions for extraction were found to be a temperature of 75℃, an initial pH (pHi) of 12, a 4-hr incubation time and a liquid-to-solid ratio of 40 mL/g; these conditions resulted in a fluorine extraction ratio of 99.0%. The effects of pH and the F/Al molar ratio on fluorine recovery and the compositional, mineralogical and morphological characteristics of the cryolite products were investigated. Field-emission scanning electron microscopy of recovered precipitates showed changes in morphology with the F/Al molar ratio. Coupling Fourier transform and infrared spectroscopy, X-ray diffraction indicated that the formation of AlF63- was restricted as increasing pH. Both the amount of fluorine recovered and the quality of the cryolite were optimized at initial pH = 3 and a F/Al molar ratio 5.75. This study proposed a reliable and environmentally friendly method for the treatment of fluoridecontaining wastes, which could be suitable for industrial applications.
