Survey analysis and chemical characterization of solid inhomogeneous samples using a general homogenization procedure including acid digestion, drying, grinding and briquetting together with X-ray fluorescence
- SP Technical Research Institute of Sweden, Brinellgatan 4, SE-501 15 Borås, Sweden
- Received 11 November 2011. Revised 10 March 2012. Accepted 24 March 2012. Available online 21 May 2012.
A survey analysis and chemical characterization methodology for inhomogeneous solid waste samples of relatively large samples (typically up to 100 g) using X-ray fluorescence following a general homogenization procedure is presented. By using a combination of acid digestion and grinding various materials can be homogenized e.g. pure metals, alloys, salts, ores, plastics, organics. In the homogenization step, solid material is fully or partly digested in a mixture of nitric acid and hydrochloric acid in an open vessel. The resulting mixture is then dried, grinded, and finally pressed to a wax briquette. The briquette is analyzed using wave-length dispersive X-ray fluorescence with fundamental parameters evaluation. The recovery of 55 elements were tested by preparing samples with known compositions using different alloys, pure metals or elements, oxides, salts and solutions of dissolved compounds. It was found that the methodology was applicable to 49 elements including Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Ce, Ta, W, Re, Ir, Pt, Au, Tl, Pb, Bi, and Th, that all had recoveries >0.8. 6 elements were lost by volatilization, including Br, I, Os, and Hg that were completely lost, and S and Ge that were partly lost. Since all lanthanides are chemically similar to La and Ce, all actinides are chemically similar to Th, and Hf is chemically similar to Zr, it is likely that the method is applicable to 77 elements. By using an internal standard such as strontium, added as strontium nitrate, samples containing relatively high concentrations of elements not measured by XRF (hydrogen to fluorine), e.g. samples containing plastics, can be analyzed.
► A methodology for performing survey analysis of inhomogeneous waste is presented. ► Waste samples are homogenized and analyzed by X-ray fluorescence. ► An internal standard is used for samples containing elements not measurable with XRF. ► 55 elements were studied and the methodology is applicable to 49 of these elements. ► The possibilities with the methodology are discussed.