• Journal of the Mineralogical Society of Korea
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• v.1 no.1
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• pp.1-14
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• 1988

최근 국내에서의 고령토의 다양한 공업적 이용추세는 다량의 고품위 고령토를 필요로 하게 되었다. 그러나 하동-산청지역의 고령토 광석은 저품위가 대부분인 반면 그 양은 막대하다. 고령토의 저품위 현상은 산화철광물과 함철 규산염광물등 고령토 이외의 광물들이 고령토 광석에 다량 함유된데 기여한다. 그릴제거, 자력분리 및 디티오나이트에 의한 침출등 종래의 정제 방법에 의하여 제작된 고령토 정광에는 아직도 상당량의 철분이 함유되어 있어서 정광의 품위가 높지 않다. 고령토 광석으로부터 분리해낸 순수한 할로이사이트는 평균 Fe2O3 0.4%를 함유하고 있으며 이 철분은 할로이사이트내에 구조철로 함유되어 있다. 고령토에 함유되어 있는 함철광물로는 산화광물(적철석, 자철석, 침철석, 티탄철석)과 규산염광물(감섬석, 버미큘라이트, 일라이트, 녹니석)이 있다. 종래의 정제방법으로는 대부분의 산화철광물들은 제거 되었지만 버미큘라이트(Fe2O3 0.9%)와 일라이트 (Fe2O3 1.2%)는 고령토 정광에 계속 남아 있어서 저품위 정광이 되고 있다. 버미큘라이트와 일라이트의 함유가 주로 고령토 정광의 저품위의 원인이 되고 있기 때문에 고품위 고령토 정광을 생산하기 위해서는 이들 두 광물을 제거해야 한다.

• Cement Symposium
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• s.40
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• pp.20-28
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• 2013

• Resources Recycling
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• v.25 no.6
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• pp.98-104
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• 2016

The purpose of this study is to obtain an optimum condition of the concentrate by floatation using Australian low grade copper ore of suitable particle size by crushing, grinding and sizing. The effect of the dosage of collector, activator, depressant and change of acidity on the floatation was investigated. The floatation conditions comprising of pH 9.0 acidity, 500g/t $CuSO_4{\cdot}5H_2O$ activator, 500g/t K.E.X. collector, 1500g/t $Na_2SO_3$ depressant and 25wt.% plup density were optimized. Grade and recovery of copper in the concentrate obtained by froth floatation under optimum conditions were 4wt.% and 65wt.% respectively.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.743-748
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• 2019

This study focuses on the simulation of wet flue gas desulfurization process for improving the production of gypsum by the utilization of low-grade limestone. At present, high-grade limestone with a $CaCO_3$ content of 94% is used for producing merchantable gypsum. In modeling process, a lot of reactions are considered to develop model. First, the limestone dissolution is simulated by RSTOIC model. Second, SOx absorption and crystallization is used by RCSTR model. Finally the gypsum is separated by using SEPERATORS model. Modeling steps make it easy to reflect further side reactions and physical disturbances. In optimization condition, constraints are set to 93% purity of gypsum, 94% desulfurization efficiency, and total use of limestone at 3710 kg/hr. Under these constraints, the mass flow of low-grade limestone was maximized. As a result, the maximum blending quantity of low-grade limestone for 2,100 kg of high-grade limestone that satisfies constraints is about 1,610 kg.

• Resources Recycling
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• v.29 no.2
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• pp.37-47
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• 2020

According to Vietnam government establishes additional thermal power plant, processing the coal ash from power plant is urgent issue. This study targeted reducing unburned carbon contents in low quality fly ash to below 6% that according to international standards. As a result, the unburned carbon contents of low quality fly ash was high and irregular as 5.3~23.6%, and it was possible to reduce unburned cabon contents to under 6%, in case of unburned carbon contents below 9.8% ashes using air classification, in case of unburned carbon contents below 23.6% ashes using combined process composed of air classification and electrostatic separation.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.512-512
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• 2009

본 연구는 자유지방산을 포함하고 있는 저품위 유지로부터 바이오디젤을 합성하는데 있어서 외부가열 방법 대신에 마이크로파를 이용한 내부 직접가열 방법으로 고체촉매 반응을 가속화한 연구에 관한 것이다. 대두유를 원료로 KOH 균일촉매를 이용한 전이에스테르화 실험에서는 섭씨 60도 상압조건에서 반응시간 3분에 95.4%의 전환율을 획득했다. 올레산과 고체산촉매를 이용한 자유지방산 제거 실험에서는 섭씨 60도 상압조건에서 solvent free 방식의 S-ZrO2는 반응시간 20분만에 93.7%의 제거율을 보였고 Rohm&Hass사의 Amberlyst-15dry 촉매는 반응시간 30분에 82.0%의 제거율을 보였다. 또한 바이오디젤 합성에 사용된 마이크로파의 총 에너지를 측정한 결과 외부가열 방법에 비해 약 1/3 수준임을 확인했다. 이것은 기존의 heat bath를 이용한 실험결과들과 비교할 때 반응속도가 약 10배 정도 향상되면서도 에너지효율이 높다는 것을 확인한 결과로서, 저품위 유지를 원료로 하는 바이오디젤 생산공정에서 마이크로파가 매우 효율적인 가열수단이 될 수 있음을 보여주었다.

• Mineral and Industry
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• v.26
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• pp.13-21
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• 2013

This study is carried out experiments on various factors for improving the grade of low grade scheelite by Knelson concentrator prior to the main beneficiation process. Even though there are several gravity separators such as Jig, Spirals and etc. for rougher concentrate, the KC3 Knelson Concentrator was adopted to get better separation efficiency and beneficiating effects for pre-concentration of the low grade scheelite ore. The feed samples was prepared to minus 1mm in size by crushing and grinding. The important factors in the KC3 Knelson Concentrator test were examined in terms of the variations such as number of treatment, feed rate, rotation speed of bowl(G force), water flow rate, pre-removal of magnetic minerals, feed size and feed grade. According to the result of experiment, it shows that the important technical variations are limited in terms of number of treatment, feed rate, feed size and feed grade. The final result shows that the KC3 Knelson Concentrator obtains the scheelite pre-concentrate of about $3%WO_3$ grade and 90% recovery, respectively, from the feed containing about $0.8-1.0%WO_3$ grade.

• Cement Symposium
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• no.21
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• pp.51-59
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• 1993

• Cement Symposium
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• s.41
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• pp.67-71
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• 2014

• Journal of Energy Engineering
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• v.23 no.2
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• pp.1-6
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• 2014

Upgrading technology has been studied for efficient utilization of low rank coal. Spray coating of heavy oil was applied on the upgrading process in order to stabilize low rank coal against spontaneous combustion. Low rank coal, which contains more than 30wt% of moisture, was upgraded to high calorific coal and stabilized by spray coating of heavy oil. It was identified that spray coating of heavy oil after drying coal is the optimum procedure of upgrading low rank coal. The experimental results show that more than 2wt% of heavy oil should be adsorbed on the coal in order to stabilize sufficiently for spontaneous combustion.