Bernard Husson

Quantitative mineralogical composition of complex mineral wastes – Contribution of the Rietveld method

The objective of the work presented in this paper is the quantitative determination of the mineral composition of two complex mineral wastes: a sewage sludge ash (SSA) and a municipal solid waste incineration fly ash (MSWIFA). The mineral compositions were determined by two different methods: the first based on calculation using the qualitative mineralogical composition of the waste combined with physicochemical analyses; the second the Rietveld method, which uses only X-ray diffraction patterns. The results obtained are coherent, showing that it is possible to quantify the mineral compositions of complex mineral waste with such methods. The apparent simplicity of the Rietveld method (due principally to the availability of software packages implementing the method) facilitates its use. However, care should be taken since the crystal structure analysis based on powder diffraction data needs experience and a thorough understanding of crystallography. So the use of another, complementary, method such as the first one used in this study, may sometimes be needed to confirm the results.

Use of treated sediments in road building techniques

ABSTRACT With a view of reducing the quantities to be landfilled, the Solvay Company has been working on the development of a treatment for polluted sediments: the Novosol® process. It allows fixing heavy metals and eliminating organic matter. This article reports on the characteristics of a treated sediment and on its use in road building techniques. From mechanical point of view, the performance of the mixtures incorporating sediments is satisfactory since their mechanical strengths are even higher than those of the reference mixtures. The leaching test carried out on the mixtures shows that the release is the same for both materials. Also, on the whole, these results suggest that using treated sediments in road building techniques is conceivable.