Abstract
Shortwave infrared (SWIR) spectroscopy can be applied directly to analyze the mineral chemistry of raw or geologic materials. It provides diagnostic spectral characteristics of the chemical composition of minerals, information that is invaluable for the identification and quality control of such materials. The present study aims to investigate the potential of SWIR spectroscopy as an alternative quality control technique for the mineral chemistry analysis of Portland cement-grade limestone. We used the spectroscopic (wavelength position and depth of absorption feature) and geochemical characteristics of limestone samples to estimate the abundance and composition of carbonate and clay minerals on rock surfaces. The depth of the carbonate (CO3) and Al-OH absorption features are linearly correlated with the contents of CaO and Al2O3 in the samples, respectively, as determined by portable X-ray fluorescence (PXRF) measurements. Variations in the wavelength position of CO3 and Al-OH absorption features are related to changes in the chemical compositions of the samples. The results showed that the dark gray and light gray limestone samples are better suited for manufacturing Portland cement clinker than the dolomitic limestone samples. This finding is based on the CaO, MgO, Al2O3, and SiO2 concentrations and compositions. The results indicate that SWIR spectroscopy is an appropriate approach for the chemical quality control of cement raw materials.
Highlights
The manufacturing process and quality of Portland cement are directly controlled by the chemistry of the raw materials used
Shortwave infrared (SWIR) spectroscopy in the 2.100–2.400 μm wavelength region is investigated in relation to the characterization of Portland cement-grade limestones to determine and estimate the chemical composition and mineral chemistry abundance on the carbonate rock surfaces
Spectral parameters, such as the wavelength position and depth of absorption feature derived from the SWIR continuum removed spectra fitted to the second-order polynomial curves, are helpful in analyzing and estimating carbonate (CO3 ) and Al-OH absorption features associated with CaO
Summary
The manufacturing process and quality of Portland cement are directly controlled by the chemistry of the raw materials used. The composition and properties of Portland cement clinker show that it is made by blending different raw materials, which are predominantly a mix of calcareous and argillaceous materials [1,2,3,4]. 2016, 8, 950 proportions of additive or corrective constituents, which may be a siliceous, aluminous, or ferruginous material or a combination of those materials, into the raw mix. The proportional estimation of the additive or corrective constituents depends on the compositional characteristics of the calcareous material as the main component in the raw mix [1,2,3,4]. The main naturally available calcareous material on the earth’s surface, as well as the preferred source of lime or calcium oxide (CaO) to make clinker, is limestone [1,2,3,4]. The suitability and availability of this carbonate rock in very large amounts are vital for the production of clinker
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