Recommendations for reporting of thermal analysis data relating to differential thermal analysis, differential scanning calorimetry,
thermogravimetry and thermomechanical analysis were developed some two decades ago. Since that time there have been significant
changes in the techniques, as well as a greater understanding of the effect of experimental variables on the results obtained
from thermonalytical experiments. This paper reports on a preliminary review of the Recommendations by the Task Group established
by the ICTAC Committee on Standardization to undertake their revision. Particular attention has been paid to the properties
of the sample; control of the instrument variables; and the data acquisition and manipulation by computers.
Black spruce /Picea mariana/ twigs and needles have been collected from a uraniferous area of northern Saskatchewan and characterized for their content of some radionuclides and trace elements in an interlaboratory program. These materials, rich in uranium, are available as reference materials, for estimating accuracy in the analysis of vegetation, from the Canadian Certified Reference Materials Project in Ottawa, Canada.
The thermal decomposition of sodium ethyl xanthate (SEX) was used to compare the techniques of pyrolysis-gas chromatography-mass
spectrometry (py-GC-MS), thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and TG-MS.
In the py-GC-MS analysis, SEX was pyrolysed at 400C in an inert atmosphere. Major gases evolved were carbon disulfide, diethyl
sulfide, ethanol, and carbonyl sulfide. The TG of SEX exhibited a sharp mass loss at 201C (42.3%) and a gradual mass loss
at 217-325C (20.8 %). The MS spectra of the evolved gases were complex due to overlapping of molecular, isotope, and fragment
ion signals. Using the MS in selected ion monitoring mode, the major gases evolved were found to be carbon disulfide and carbonyl
sulfide. The FTIR spectra of the evolved gases displayed vibrational frequencies due to alkanes, carbonyls, carbonyl sulfide,
and carbon disulfide.
From the analyses it was concluded that py-GC-MS provided unambiguous gas identification. Interpretation of the MS results
was reliant on the py-GC-MS results, and the FTIR data was limited to identifying gases with very characteristic vibration
Four mineral sulfides typically found in the feed stock of a commercial nickel flash smelter, namely pyrite, violarite, pyrrhotite and pentlandite, were isolated from a primary and a supergene ore sample using magnetic separation. Relatively pure samples of pyrite, pyrrhotite and pentlandite were obtained, but violarite could only be upgraded to a 40–50% mixture with pyrite. These samples were characterized by chemical analysis, optical microscopy, Electron Probe Microanalysis (EPMA), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Thermogravimetry-Differential Thermal Analysis (TG-DTA). Each sample was split into four fractions of particle size 20–45Μm, 45–75Μm, 75–90Μm and 90–125Μm. Ignition temperatures and extents of reaction were determined using an isothermal thermogravimeter, and the products were characterized by electron microscopy. Pyrite and violarite were found to be the most reactive to ignition, followed by pyrrhotite, with pentlandite being the least reactive. This order contradicts the results of other studies and various possible causes for this are discussed. The observed trend of increasing ignition temperature with increasing particle size was in agreement with previously published reports. The extent of reaction of each mineral was measured at increasing furnace preheat temperatures. These plots were correlated with the morphology of the products formed at the ignition temperature.
The quantitative interpretation of X-ray fluorescence (XRF) data is often difficult because of matrix effects. The intensity
of fluorescence measured for a given element is not only dependent on the element's concentration, but also on the mass absorption
coefficients of the sample for the excitation and fluorescence radiation. Also, there are interelement effects in which high-energy
fluorescence from heavier elements is absorbed by ligher elements, with a resulting enhancement of their fluorescence. Recent
theoretical treatments of this problem have shown that X-ray fluorescence data can be corrected for these matrix effects by
calculations based on first principles. Fundamental constants, available in atomic physics data tables, are the only parameters
needed. It is not necessary to make empirical calibrations. In this paper we report the application of this correctional procedure
to alloys and alumina-supported catalysts. We also discuss how it may be applied to other matrices. A description is given
of a low-background spectrometer which uses monochromatic AgKα radiation for excitation. Matrix corrections by first principles can be easily applied to data from instruments of this type
because fluorescence excitation cross-sections and mass absorption coefficients can be accurately defined for monochromatic
A sample of chalcocite (Cu2S) of particle size 45–75 μm was heated in air at 10°C min−1 in a simultaneous TG-DTA apparatus. The phase compositions of the products at various temperatures were quantitatively determined
by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and wet chemical analyses. Copper(II) sulfate,
of amount 1.7% by mass, was observed at 435°C and increased rapidly in concentration to 56% at 570°C. From 570–670°C, there
was a rapid decrease in CuSO4 content to 9.8% as the phase converted to CuSO4·CuO, with the CuSO4 not being detected at 775°C. From 435–570°C, Cu2O formed, but at a rather slower rate, reaching 47% at 570°C. The Cu2O level then decreased to 38% over the range 570–670°C. CuSO4·CuO was first detected at 570°C by FTIR, although it was not detected by XRD at this temperature. The content of this species
reached 41% at 670°C, decreased to 24% at 775°C, and was not detected at 840°C. CuO first appeared at 670°C and rose steadily
in concentration until at 840°C it was the only compound present.