Analysis of nickel refinery dusts

After characterization of bulk samples by inductively coupled plasma emission spectroscopic (ICP-ES) quantitative analysis and X-ray powder diffraction studies, single particle techniques using quantitative image analysis, scanning electron microscopy--energy dispersive analysis by X-ray, and finally laser beam ionization mass spectrometry analysis (LIMA) for surface analysis have been applied to historical nickel refinery dust samples from the nickel refining plant at Clydach in Wales. There were two historical samples of processed material from 1920 and 1929. These samples had a remarkably small particle size range, mean 3 microns and range, 0.75-24 microns. The most significant difference in elemental composition was the presence of 10% arsenic in the 1920 sample compared with 1% in the 1929 sample. The X-ray spectra revealed the presence of NiO in both. However, surprisingly, CuO was identified only in the 1929 sample. Of particular interest was the presence of a component, in the 1920 sample only, identified as the mineral orcelite, a copper-iron-nickel-arsenide-sulphide mineral, predominantly, Ni5-XAs2. Using the LIMA technique, it was found that in both samples, arsenic and arsenic derivative peaks are prominent, indicating the surface availability of arsenic compounds.