Spectrographic determination of tungsten in ores and concentrates employing an intermittent a.c. arc between copper electrodes

Tungstic oxide has been determined in ores and concentrates by emission spectrography in the range 6–65%. Silica is used to dilute the sample ten-fold. Silver chloride is used as a buffer and nickel (oxide) as internal standard. To avoid formation of refractory tungsten carbide over graphite electrodes, copper electrodes are used. The effect of the presence of calcium oxide, manganese dioxide and iron oxide on tungsten determination is studied. Samples analysed by chemical and spectrographic methods show good agreement.