Determination of W, Mo and Bi in Skarn-Type Polymetallic Tungsten Ore by ICP-AES with Penta Acid Digestion

The dried sample (0.100 0 g) was digested with hydrochloric acid-phosphoric acid-hydrofluoric acid-nitric acid-perchloric acid as acid system. After digestion, 20 mL of hydrochloric acid was added and water was used to make its volume up to 200 mL. W, Mo and Bi were determined by inductively coupled plasma-atomic emission spectroscopy. The radio frequency power was set to 1 150 W, with the atomizing gas flow of 0.50 L·min^-1, the auxiliary gas flow of 1.00 L·min^-1. The spectral lines of W, Mo and Bi were 239.7, 202.0 nm and 223.0 nm, respectively. It was shown that linear relationships between values of mass concentration of W, Mo and Bi and their response values were kept in the definite ranges, with detection limits in the range of 0.002 4%-0.003 8%. The standard substances of skarn-type polymetallic tungsten ore were determined, and the absolute values of relative errors between the determined values and the certified values were less than 7.7%, with RSDs (n=12) of the determined values less than 5.5%. Test for recovery was made on the actual sample, giving results in the range of 96.2%-101%. The determined values of W, Mo and Bi were basically consistent by this method and the national standard methods.