The Research On The Rapid Detection Methods Of The Harmful Elements In Minerals

With the rapid development of industrialization and urbanization as well as the domestic and foreign trade and prosperity, minerals import and export trade will not only satisfy the demand for mineral resources in our country, but also can increase our country's economy through some minerals exports. Because of the complexity of the regional distribution of mineral resources, it will be introduced the harmful elements. So it is very important to analyze the poisonous and harmful elements in minerals.This paper is divided into three parts: one is the determination of total arsenic content in the fluorite; the second is the determination of total cadmium content in iron ore; and the last part is total chlorine content in coal mine.1. Make up a complete validation procedures of chemical analysis methods including in-house validation and collaborative study validation. In-house validation is necessary before executing the collaborative study validation to ensure the feasibility of the method. The project group developed five fluorite validation samples with different levels of arsenic content and made sure the homogeneity and stability of the samples, validating robustness, linear, detection limit,accuracy and precision. The results showed that the particle size of the samples should be less than63?m. Catching acid using the system of HNO3 and HClO4 was more suitable than water bath using aqua regia(1+1) as a sample pretreatment method and thiourea-ascorbic acid solution could eliminate the interference of coexisting ions. The LOQ of the method was 0.04 ?g/g. The concentration of arsenic in the range of 0.1 ng/mL~50 ng/mL exhibited good linearity and the correlation coefficient was 0.9997. Repeatability standard deviation of the method was between1.3% and 5.0%(n=6). The recovery of the method was between 85.0% and 103.7%. The result had no significant difference in 97.5% confidence interval when comparing with the DDTC-Ag method and the accuracy of the method is validated further.The collaborative study validation involved 10 collaborative laboratories and 5 validation samples. After Mandel test, Cochran test and Grubbs test, repeatability and reproducibility of the method were acquired. The results showed that, in the range of 0.0000102%~0.007656% of arsenic content in fluorite, repeatability standard deviation were between 0.00000231% and 0.0001919% with the function relationship of Sr=0.0246m+0.00000276, and reproducibility standard deviation were between 0.00000255%and 0.0004153% with the function relationship of SR=0.0532m+0.0000167.The national standard,fluorite-determination of arsenic content-hydride generation-atomic fluorescence spectrometry, is based of the validation.2. The method of determination of cadmium in iron ores by atomic fluorescence spectrometry was optimized.The best sensitization system was thiourea 10g/L-Ascorbic acid10g/L-Ni 0.5 ?g/m L.The most appropriate amount of Fe matrix, 0.78g/L and sample quantity,0.2g, were determined through investigating the influence of Fe on the determination of Cd.The optimized method was validated through measuring the determination of Cd in the four iron ore samples.The results showed that the detection limit of the method for Cd was 0.075?g/g with dynamic linear range of 0ng/mL~50ng/mL.The correlation coefficient was 0.9994.The recovery of the method for Cd was 85.4%~109.2% with the precision range of 5.8%~8.7%(n=6).The optimized method meet with the determination of trace cadmium in iron ore.3. Developed a new method to analyse chloride in coal by combining a new instrument named automatic quick furnace(AQF) which can do the preparation of solid samples by burning and ion chromatography together. This method exerts the abilities of AQF which can treat sample fast and the advantages of ion chromatography.We only need 18 minutes to treat a single sample on average by AQF-IC.The detection limits of chlorine were 0.0864mg/L with correlation coeffient of 0.9993.The RSD ranges of the method for the determination of chlorine in sample and standard were 2.39%~7.41%, and the average recovery ranges for chlorine were84.27%~110.82%.Compare the determination results with the results of GB/T 3558-2014, sample melting by Eschka reagent- potassium hydrogen sulfate titration, verifying the accuracy of the method further.