Publication: Study on fine grinding of mica in jet mill for filler application in plastic
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Date
2009-05-01
Authors
Yung, Mei Hua
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Abstract
This main objective of this study is to produce ultrafine mica below 10µm in order to fulfill the requirement as filler for plastic industry. Fine grinding process of mica was carried out in an Alpine 100 AFG air jet mill by varying the operation parameters such as feed rate, classifier rotational speed and grinding pressure. The ground products were characterized by X-ray Fluorescence (XRF), Particle Size Analysis (PSA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrafred Spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and density test. The predominant constituents of the sample were 52% SiO2 and 35% Al2O3. The size reduction and mechanochemical effect of mica take place simultaneously as the jet mill is an energy intensive grinding mill. The minimum particle size obtained was 5.85µm with a span value of 1.08. Degree crystallinity of ground mica was ranging from 28.90% to 84.62%. The crystallite size ranged from 2.410nm to 7.496nm whilst lattice strain ranged from 0.246 to 1.056. Delamination and destructive breakage mechanism took place according to the varying operation parameters of the jet mill. Si-O stretching bands exhibited as the main bonding in mica. The specific surface area increased as particle size decreased and ranged from 7.099 m²/g to 36.105 m²/g. For density test, the density of the ground mica ranged from 2.6014 g/cm³ to 2.7572 g/cm³.