Comparison of Two Different Sample Digestion Methods for Determination of Tungsten, Molybdenum, and Bismuth in Polymetallic Ore by Inductively Coupled Plasma-Optical Emission Spectrometry
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ABSTRACT
BACKGROUNDCurrently, tungsten, molybdenum, and bismuth contents are mainly determined by the traditional potassium thiocyanate colorimetric method and EDTA volumetric method. These methods are based on single-element analysis, which has a complicated operation process, low analysis efficiency, and long detection cycle. It is difficult to meet the requirements of accurate and rapid determination of many samples.OBJECTIVESTo improve the traditional single-element analysis method for the determination of tungsten, molybdenum, and bismuth in polymetallic ore.METHODSA rapid method for the simultaneous determination of tungsten, molybdenum, and bismuth in the ore sample was developed by comparing the two digestion methods of HCl-H3PO4-HClO4-HNO3 and HCl-HClO4-HNO3, and was subsequently combined with inductively coupled plasma-optical emission spectrometry.RESULTSTungsten, molybdenum, and bismuth in the sample were digested more thoroughly using the four-acid digestion method with a reasonable addition of phosphoric acid. The relative error between the determined and certified values of each element ranged from -5.36% to -1.39%, which indicated higher accuracy. The relative standard deviation was ≤ 4.18%, and the detection limits of the method ranged from 0.0027% to 0.0037%. The method was employed for the analysis of actual samples of the polymetallic ore from a certain area in Chenzhou, Hunan Province. The recovery of each element ranged from 95.0% to 103.0%. All the technical indexes were better than those of the three-acid digestion method.CONCLUSIONSThe developed method significantly improved the analysis efficiency and gave accurate and reliable results. The method has been verified by actual samples and is suitable for batch detection of tungsten, molybdenum, bismuth, and other major and trace elements in the polymetallic ore samples.
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