• Resources Recycling
• /
• v.18 no.5
• /
• pp.19-25
• /
• 2009

Molybdenite concentrate ($MoS_2$) is the major mineral for the molybdenum industry, of which the industrial processing is first converted to technical grade molybdenum trioxide ($MoO_3$) by its oxidative roasting and purification, used as a raw material for manufacturing several molybdenum compounds. In the present work, detailed experimental results for the oxidative roasting of low grade Mongolian molybdenite concentrate are presented. The experiments were carried out in the temperature range of 793 to 823 K under an oxygen partial pressure range of 0.08 atm to 0.21 atm by using a thermogravimetric analysis technique. The molybdenite concentrate was an average particle size of $67\;{\mu}m$. In the oxidative roasting of low grade Mongolian molybdenite concentrate, more than 95% of molybdenite was converted to molybdenum trioxide in 60 min. at 828 K. The lander equation was found to be useful in describing the rates of the oxidative roasting and the reaction order with respect to oxygen concentration in a gaseous mixture with nitrogen was 0.11 order.

• Resources Recycling
• /
• v.31 no.6
• /
• pp.73-80
• /
• 2022

This study investigated the mineralogical characteristics and basic flotation properties of domestic molybdenum ores. The source mineral of molybdenum was identified as molybdenite, and the main gangue minerals in the raw ore were silicate minerals. Copper, lead, and zinc were also found in trace amounts. Based on the results of basic flotation properties, molybdenite's zeta potential showed negative charges in all pH ranges. The contact angle of molybdenite increased with pH, reaching a maximum of 74° at pH 9. In optimal conditions, the grade and recovery of the concentrate by unit flotation were MoS2 82.4% and 92.04%, respectively. Further investigation of the impurities in the concentrate revealed a sulfide mineral with surface characteristics similar to molybdenite and silicate minerals combined with molybdenite, which may degrade the quality of the concentrate. To improve the concentrate quality, we intend to control silicate minerals through regrinding and liberation and use column flotation to improve fine particle separation efficiency.

• Journal of the Mineralogical Society of Korea
• /
• v.14 no.1
• /
• pp.52-57
• /
• 2001

옥천대의 탄질 흑색 점파암에 최대 1000 ppm까지 부화되어 있는 몰리브덴의 광물학적 존재형태를 밝히기 위하여 충청북도 괴산군 덕평지역 흑색점판암에 대하여 박편제작, X선회절분석, 중성자활성화학분석, 주사전자현미경관찰, 에너지분산 X선분석, 파장분산 X선분석 등을 실시하였다. 그결과 몰리브덴은 두께 $1~2\mu$m 정도의 극미립 엽상 휘수연석($MoS_2$)으로 존재함이 판명되었다. 휘수연석은 흔히나이트의 포획물로 산출된다. 탄질흑색 점판암에 우라늄 및 바다듐과 함께 다량의 몰리브덴이 함유되어 있음에도 과거의 연구에서 그 존재형태가 규명되지 않은원인은, 극미립 휘수연석이 불투명한 세립 탄질기질에 분산 분포하기 때문이다.

• Korean Journal of Food Science and Technology
• /
• v.50 no.5
• /
• pp.486-491
• /
• 2018

This study investigated the qualitative characteristics of Sooyeon noodles supplemented by sorghum powder at concentrations of 10, 15, 20, and 25%. L- and b-values of Sooyeon noodles decreased while its a-value was significantly increased by the addition of sorghum powder. Additionally, sorghum powder increased the weight, volume, and water uptake of noodles. Turbidity as well as cooking loss of cooked noodles decreased significantly due to the addition of sorghum powder. Increasing concentration levels of sorghum powder resulted in an increase in the hardness of cooked noodles, which was in the range of 1,236-1,932 g, and a decrease in tension, which was in the range of 152-105 g. The same trend was observed in the dough production process. Sooyeon noodles with 25% sorghum powder yielded the highest total polyphenol content (3.668 GAE mg/g) and flavonoid content (1.893 CE mg/g). DPPH and ABTS radical scavenging activities increased linearly to 0.704 and 0.815 AA mg/g, and 0.355 and 0.935 AA mg/g. respectively.

• TTA Journal
• /
• s.35
• /
• pp.49-54
• /
• 1994

• 건강소식
• /
• v.31 no.4 s.341
• /
• pp.14-15
• /
• 2007

• 건강소식
• /
• v.30 no.8 s.333
• /
• pp.14-15
• /
• 2006

• KLA journal
• /
• v.46 no.5 s.360
• /
• pp.42-44
• /
• 2005

• 건강소식
• /
• v.31 no.3 s.340
• /
• pp.18-19
• /
• 2007

• 건강소식
• /
• v.30 no.10 s.335
• /
• pp.14-15
• /
• 2006