ICP-AES Determination of Phosphorus in Tungsten Concentrate with Ferric Hydroxide Coprecipitation

The sample of tungsten concentrate was digested with HCl and HNO₃-HF-HClO₄ (by volume ratio of 1:1:1) mixed solution in a closed PTFE sample dissolving tank. In ammonia, the trace phosphorus was separated with tungsten and copper in the matrix by coprecipitation with Fe(OH)₃. ICP-AES was used to determine the concentration of phosphorus. The 214.914 nm spectral line was selected as the phosphorus analysis spectral line, and the spectral interference of tungsten to phosphorus was eliminated by the interference coefficient correction method.Linear relationship between values of spectral intensity and mass concentration of phosphorus was kept in the range within 10 mg·L^-1, with detection limit (3σ) of 28 μg·g^-1. The proposed method was applied to the determination of phosphorus in tungsten concentrate samples, values of RSD (n=12) found were in the range of 2.4%-5.1%. The results obtained by the proposed method were consistent with those of the national standard method.