Determination Of Gallium In Fly Ash By Inductively Coupled Plasma Atomic Emission Spectrometry

As a kind of scattered element,applications of metallic element gallium are very broad,and the market demand for gallium is improving gradually.Fly ash is a kind of solid waste with certain content of gallium that can be extracted for recycling.An important prerequisite for extracting gallium in fly ash is the determination of gallium quickly and accurately.Conventional method-Spectrophotometry for the analysis of the element Gallium has some disadvantages,such as the cumbersome process and not environmentally friendly,and the use of inductively coupled plasma atomic emission spectrometry(ICP-AES)for determination of gallium in the fly ash can solve these problems.The fly ash in Shizuishan power plant of Ningxia was made as the main sample and acid dissolution method was used for sample pre-treatment.Considering detection limit and reaction time,the weight of 0.25g was selected.According the six characteristic lines of Ga corresponding to the BEC and DL in ICP spectrometer,the wavelength of 294.364nm with lowest BEC and DL was chose as analytical line.Observing the intensity and waveform diagram of lmg/L gallium standard solution in ICP spectrometer with different transmit power and carrier gas,transmit power and carrier gas flow rates were set to 1300W and 0.60L/min.Through the condition experiments,when HCl was added and temperature rised,it made GaCl3 volatile and content of the gallium low.Therefore HCl can not be used to dissolve sample.The amount of nitric acid didn't significantly affect to determination of gallium,from two aspects of safety and reaction time,choose 3mL as the amount of nitrate.The intensity of the gallium increased with HF(1-10 mL).When HF added was more than 10mL,content of gallium unchanged,therefore HF was added in an amount of 10mL.High solution temperature caused partial acid volatile,making the sample can not be completely dissolved,thereby enabling the analysis of results was low,and therefore the temperature for samples dissolved was set at 130?150?.The content of gallium in fly ash of the power plant was about 26.80?g/g and the detection limit of the method was 0.58?g/g.Precision of the method were good with its relative standard deviation(RSD)of 4.51%.Compared with mass spectrometry experiments,the results meet the requirements of analysis.The method recoveries were between 94.45 and 105.4%.The fly ash sample was molten by Alkali fusion(lithium borate LiBO2),with the sample weight of 0.2g,the amount of lithium borate of 0.8g,melting temperature of 1050? and determined by ICP-AES.The results by Alkali fusion and that of acid dissolution were similar.In view of its high requirements of the reaction conditions and low operability,therefore the method of acid dissolution was selected for pre-treatment of fly ash.