METAL ANALYSIS IN PETROLEUM COKE BY WAVELENGTH DISPERSIVE X-RAY SPECTROSCOPY: ASTM D6376
EXPLANATION
The presence and concentration of sulfur and various metallic elements in a petroleum coke are major factors determining the suitability of a coke for various purposes. This test method provides a rapid means of measuring these elements in coke samples, and provides a guide for determining conformance to material specifications used by buyers and sellers in commercial transfer of petroleum coke. Sulfur content can also be used to evaluate potential formation of sulfur oxides, a source of atmospheric pollution. This test method using X-ray fluorescence spectrometry specifically determines sodium, aluminum, silicon, sulfur, calcium, titanium, vanadium, manganese, iron, and nickel. This test method may be applicable to additional elements if appropriate standards are available.
Appropriate matrix and interelement spectral interferences need to be corrected to obtain accurate results.
TEST SUMMARY
A weighed portion of a sample of petroleum coke dried at 110° C and crushed to pass a 200-mesh sieve is mixed with stearic acid and then milled and compressed into a smooth pellet. The pellet is then irradiated with an X-ray beam. The characteristic X-rays of the elements analyzed are excited, separated and detected by the wavelength dispersive X-ray spectrometer. The measured X-ray intensities are converted to elemental concentration by using a calibration equation derived from the analysis of the standard materials. The K-alpha spectral lines are used for all of the elements determined by this test method.
TEST PRECISION
The precision and bias of this test method are under development at present.
