Phosphogypsum:Part Ⅰ:Mineralogical,Thermogravimetric,Chemical and Infrared Characterization

Phosphogypsum (PG) derived from the dissolution of phosphate ore in H2SO4 has been characterized by using chemical and thermogravimetric analyses, X-ray difFraction and infrared spectrum to give an idea about the future utifization of this waste material. The PG under the investigation was free from the radioactive elements and Cd and contained about 141 × 10-6 rare earth elements in total, which favours the utilization of this material. PG was formed mainIy of gypsum, little anhydrite and quartz and rare kaolinite. It exhibited two large endothermic peaks corresponding to the dehydration of the sample and a small one which may be attributed to the Iiberation of the residual water that may be found in the soluble anhydrite. Also, an exothermic peak was observed which may be related to the transformation of soluble (γ-anhydrite) to insoluble β-anhydrite. PG exhibited the same absorption bands as that observed for chemical CaSO4.2H2O and natural gypsum samples besides the appearance of a weak band at 840 cm-1 which characterizes the vibration of H2PO4- group

Thermogravimetric coupled with Fourier transform infrared analysis study on thermal treatment of monopotassium phosphate residue

In China,safe disposal of hazardous waste is more and more a necessity,urged by rapid economic development.The pyrolysis and combustion characteristics of a residue from producing monopotassium phosphate(monopotassium phosphate residue),considered as a hazardous waste,were studied using a thermogravimetric,coupled with Fourier transform infrared analyzer(TGFTIR).Both pyrolysis and combustion runs can be subdivided into three stages:drying,thermal decomposition,and final devolatilization.The average weight loss rate during fast thermal decomposition stage in pyrolysis is higher than combustion.Acetic acid,methane,pentane,(acetyl)cyclopropane,2,4,6-trichlorophenol,CO,and CO_(2) were distinguished in the pyrolysis process,while CO_(2) was the dominant combustion product.

Pyrolysis behaviors of oil sludge based on TG/FTIR and PY-GC/MS

Pyrolysis is an alternative technology for oil sludge treatment.Thermogravimetric Analysis-Fourier Transform Infrared Spectroscopy and Pyrolysis-Gas Chromatography/Mass Spectrometry were employed to investigate the pyrolysis process and products of oil sludge.The pyrolysis process was divided into five stages:drying and gas desorption,oil volatilization,main pyrolysis,semicoke charring,and mineral decomposition.The main reaction temperatures ranged from 497.6 K to 753.2 K.The products were mainly composed of pairs of alkane and alkene(carbon number ranges from 1 to 27).The mechanisms consisted of random chain scission followed by end chain scission at high temperatures with volatilization occurring during the whole process.This study is useful not only for the proper design of a pyrolysis system,but also for improving the utilization of liquid oil products.