Determination of Tungsten Content in Tungsten Carbide and Waste Product by X-ray Fluorescence Spectrometry with Fusion Sample Preparation

Tungsten carbide is widely used in the production of cemented carbide materials and the content of tungsten in tungsten carbide has a significant impact on its performance and cargo accounts settlement. The ratio error and grinding in the production process produces generous tungsten-containing waste, and the recovery of tungsten from waste material can make up for the shortage of tungsten resources, so it is important to determine tungsten in tungsten carbide and its waste. At present, the determination of tungsten in tungsten carbide is usually estimated by the national standard and is analyzed by using the cinchonine gravimetric method. The method has high accuracy, but, only for the detection of tungsten trioxide content greater than 50% of the sample and the process is tedious and work intensive. According to the characteristics of tungsten carbide, such as easy oxidation at high temperature, reference to the international standard ASTM B890-07, it can be converted into tungsten trioxide, and the tungsten content can then be detected by melting the sample preparation for X-ray Fluorescence Spectrometry (XRF). To achieve this, the tungsten carbide was first placed in a muffle furnace to make convert the tungsten completely into tungsten trioxide, then tantalum pentoxide was added as the internal standard, with sodium borate-lithium tetraborate as mixed solvent, to a temperature of 1150℃ to make a sample piece, and then the tungsten was determined by XRF. Experiments show that the optimum temperature of ignition is 800℃, and at this temperature tungsten carbide is completely converted into tungsten trioxide, so the tungsten carbide fusion sample preparation, which is normally considered difficult is effectively solved; the precision of the method (RSD) is 0.2; the actual sample determination value is consistent with the national standard method (cinchonine gravimetric method); tungsten trioxide content range is 30%-100% through measure. The analysis time is greatly shortened and it meets the need of a large number of actual sample detection.