Determination of 6 Platinum Group Elements in Copper Concentrate by Inductively Coupled Plasma Mass Spectrometry with Nickel Sulphide Fire Assay

In response to the current problem of complex slag separation operation and difficulty in meeting production requirements in the determination of elements in copper concentrates by inductively coupled plasma mass spectrometry (ICP-MS) with fire assay, the assay ingredients had been optimized and a research mentioned by the title was conducted. 5 g of the sample was taken, mixed with 30 g of borax, 15 g of sodium carbonate, 1 g of sublimated sulfur, 10 g of silica, 3 g of sodium nitrate, 10 g of calcium fluoride, 4 g of carbonyl iron powder, and 1.5 g of carbonyl nickel powder. The mixture was placed in a clay crucible, and covered with a mixture of lightweight magnesium oxide-silicon carbide at a mass ratio of 3∶1, keeping at 1 050 ℃ for 15 min. After cooling, the matte buckle was taken and placed in a 100 mL-ground triangular flask. 30 mL of water was added, and 30 mL of hydrochloric acid was added after the matte buckle was dispersed. The mixture was dissolved at 160 ℃ until the solution was clear and no bubbles emerged. After cooling, the mixture was filtered with a 0.45 µm mixed cellulose filter membrane and washed with 10% (volume fraction) hydrochloric acid solution. The sediment was transfered into a ground triangular flask, and 5 mL of aqua regia (a mixture of hydrochloric acid and nitric acid at a volume ratio of 3∶1) was added. The sediment was dissolved at 120 ℃ until the solution was clear and made its volume up to 25 mL with water. 6 platinum group elements were determined by ICP-MS in collision pool mode. As shown by the results, sodium nitrate in the assay ingredients reduced the excess reducing power in the sample, and avoided the entry of base metals into the sulforaphane, in order to obtain a suitable quality matte buckle. Calcium fluoride improved the fluidity of slag, and was easier for the slag to settle. A mixture of lightweight magnesium oxide-silicon carbide at a mass ratio of 3∶1 as the covering agent could effectively reduce the loss of osmium and ruthenium during the melting process. Linear relationships between the corresponding response intensity and the internal standard (lutetium) response intensity ratios and mass concentrations of elements were found within 100.0 μg·L⁻¹, with detection limits (3s) of 0.017-0.139 μg·kg⁻¹. This method was used for the analysis of national standard substances, with RSDs (n=12) of the determined values less than 8.0%. Test for recovery was made on the blank sample by standard addition method, giving results in the range of 90.0%-109％.