• Explosives and Blasting
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• v.42 no.3
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• pp.38-48
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• 2024

This study is to evaluate the applicability of high-speed, high-pressure dynamic compression technology for the powder molding of talc. To achieve this, powder molding test was conducted using a self-developed high-speed, high-pressure dynamic compression device, and the results were analyzed. Additionally, the behavior characteristics of pyrophyllite powder particles under dynamic compression were analyzed using the PFC2D. Quantitative analyses, as well as mapping and point analyses, were conducted using the SEM on pyrophyllite from the Naju ceramic Mine and the Bugok mine. The results showed that the weight ratio of composed elements in both mines was in the order of oxygen > silicon > aluminum. A pyrophyllite powder solid with a diameter of 14.5 mm and a thickness of 3 mm was successfully produced using a high-speed, high-pressure dynamic compression device capable of generating an instantaneous compressive force with a 30 kgf projectile dropped from a height of 1.5 m in about 0.4 seconds. Numerical analysis of pyrophyllite powder using PFC2D analyzed that in the numerical model, the compression ratio was approximately 56%, and the porosity decreased from 16.0% to 1.0%, indicating almost no remaining pores.

• The Journal of Engineering Geology
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• v.34 no.3
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• pp.403-413
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• 2024

This study aims to investigate the material properties of specimens made from pyrophyllite and pyrophyllite-aluminum mixed powders using high-speed, high-pressure dynamic compression technology. The aluminum powder exhibited a highly uniform particle size distribution ranging from 10 to 100 ㎛, whereas the pyrophyllite powder displayed four distinct particle size distributions: 0.1~1 ㎛, 1~10 ㎛, 80~100 ㎛, and 200~1,000 ㎛. Using high-speed, high-pressure dynamic compression technology with a drop time of approximately 0.34~0.4 seconds and a dynamic load of about 207 tonf, it was possible to fabricate pyrophyllite and pyrophyllite-aluminum mixed powder specimens with a volume of about 548 mm². The Shore hardness measurement results showed that specimen BG100 had an average of 43.7, BG90 had an average of 33.2, and BG85, BG80, BG75, and BG70 had an average of 31.0, indicating that the specimen with the least aluminum content exhibited the highest Shore hardness value. The thermogravimetric analysis revealed mass losses at two points: the first mass loss occurred at around 270℃ with a loss of approximately 1.45%, and the second mass loss occurred at around 600℃, where BG70 and BG80 showed a mass loss of about 2.53%, and BG75, BG85, and BG90 showed a mass loss of about 3.43%. Scanning electron microscopy analysis indicated that the microstructure of the specimens was similar regardless of the mixing ratio, with three elements-O, Si, and Al-being detected in all specimens. The mapping analysis of BG90 revealed an oxygen weight ratio of 50.80%, silicon weight ratio of 37.36%, and aluminum weight ratio of 11.85%. In the case of BG85, the results were 43.09% oxygen, 43.50% silicon, and 13.41% aluminum; for BG80, the results were 44.83% oxygen, 40.30% silicon, and 14.87% aluminum; for BG75, the results were 44.71% oxygen, 35.49% silicon, and 19.80% aluminum; and for BG70, the results were 34.95% oxygen, 35.73% silicon, and 29.32% aluminum.