Investigation of the effect of mechanical activation on the structural changes of fluorapatite using X-ray diffraction analysis method

Document Type : Original Research

Authors
A Hadi Shadi Naghadeh
P. Pourghahramani
10.22034/jaert.1.2.41
Abstract
In this study, a planetary ball mill was used for mechanical activation of phosphate concentrate by dry milling in argon atmosphere. To investigate the structural changes of fluorapatite, amorphization degree, crystallite size, micro-strain, particles size, specific surface area changes and new phase formation were investigated. The crystallite size and micro-strain were estimated using Williamson-Hall method. To investigate the influence of effective parameters on mechanical activation, the ball to powder ratio of 20:1 and 40:1 with two types of balls of 9.4 and 20 mm and speeds of 200 and 500 rpm was used. The results showed that agglomeration of particles occur at higher intensities of mechanical activation, but no phase change occurs during high intensity ball milling. The most variations in crystallite size, micro-strain, surface area, amorphization degree and XRD line broadening were for samples that were activated by smaller balls for longer time. The results of the Williamson-Hall plots showed that the maximum effect of mechanical activation on phosphate concentrate was in the first 20 minutes with small balls and the crystallite size, micro-strain and amorphization degree was changed from 225 nm, 0.09% and 0% for initial sample to 64.29 nm, 0.9% and 80.081% for mechanically activated sample, respectively. Also the results showed that changes in cell parameter at c direction had larger effect on unit cell volume. The maximum unit cell volume variations were corresponding to mechanically activated sample with 9.4 mm balls that changed from 525.4 (A3) for initial sample to 528 (A3) for activated one after 90 min.

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