Effect Of Jet Mill Operating Parameters During The Production Of Ultrafine Limestone
Loading...
Date
2011-01
Authors
Jamil, Noorina Hidayu
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Fine grinding of limestone in jet mill was carried out by varying the operational parameters such as feed rate, classifier rotational speed and grinding pressure at five levels. Besides that the inside mill condition such as holdup mass and grinding camber pressure was noted as well. The ground particle was characterized for particle size and its distribution, mechanochemical effect and improvement in particle shape. The ground product exhibits poly-modal distribution where the volume moment diameter ranged from 2.11μm to 7.12μm whilst the span values are in between 1.1 to 2.9. Finer particles were obtained at overpressure grinding chamber condition and the mass of holdup of 1500g. The mechanochemical effect was characterized through X-ray diffractogram and FTIR. The X-ray diffraction pattern exhibits reduction in peak intensity, peak base broadening and shift in peak position. The degree of crystallinity of the ground particles ranged from from 27.56% to 97.12%. The crystallite size ranged from 144.1nm to 228.2nm whilst lattice strain ranged from 0.153 to 0.201. The expansion of crystal lattice was observed in the ground samples. The IR spectra exhibits reduction of O-H band which indicate the mechanochemical effect has taken place. The particle shape was characterized through circularity values where a reduction of 30% in this value was observed in the ground particles. Abrasion breakage mechanism facilitates breakage of particles edges which produces sub-micron particles whilst impact breakage mechanism produces micron size particles. Limestone particles below 10m with narrow distribution and improved particle shape with partially amorphous characteristics is suitable for filler application in various manufacturing products.
Description
Keywords
Jet Mill , Ultrafine Limestone