Analysing iron ores with Mossbauer spectroscopy

In previous papers (1, 2) the authors have pointed out the influence of the grain size on the shape of the Mossbauer spectra of goethite (α-FeOOH). In this paper the correlation between the particle size and the relative Mossbauer constant of goethite is investigated. It is found that only those goethite samples which have in their Mossbauer spectra a “superparamagnetic” fraction at room temperature show a variation of the relative Mossbauer constant with respect to well crystallized materials so that for such samples correction has to be made in Mossbauer quantitative analyses. Further the relative Mossbauer constants for all the iron compounds appearing in iron ores have been determined, taking into account the eventual excess of water. The knowledge of these data enabled us to determine the composition of several iron ores.