• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.870-873
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• 2000

This investigation reports the grinding characteristics of quartz. Grinding experiments were performed at various grinding conditions including wheel mesh, table speed and depth of cut. The grinding forces and specific grinding energies were measured to compare the grindability of quartz with those of structural ceramics such as A1$_2$O$_3$, SiC, Si$_3$N$_4$ and ZrO$_2$. Surface roughness was also measured with tracer and the ground surfaces were observed with SEM. The chip formation energy of quartz was about 6J/㎣, which is quite smaller than those of structural ceramics. Although plastic flows are occured in Si$_3$N$_4$ and ZrO$_2$, micro/macro cracks are occured in ground surface of quartz like in A1$_2$O$_3$ and SiC.

• 한국자동차공학회논문집
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• 제2권6호
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• pp.38-49
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• 1994

In this study, grindability of some representative engineering ceramics are experimentally investigated using resin bond diamond wheel with conventional surface grinding machine, and proper grinding conditions which can be obtained from various experimental results are established also for mechanical components which are proper to domestic circumstances with high reliability. And through the results of experiment, it is confirmed that grinding energies of the ceramics, especially in the case of $Al_2O_3$, are lower than steel with same machining condition in the conventional grinding because of their fine-brittle fracture mode type removal process, though the ceramics are well-known to unmachinable materials. And moreover, the total pass numbers needed for spark-out process to be completed are depend on their mechanical properties because that grinding stiffness is different from each other. The grinding force, ginding power and ground surface roughness are also measured and compared. Furthermore, the experiments carried out in this study, some useful results are obtained with can guide to grind engineering ceramics with conventional surface grinding machine.

• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.196-205
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• 2015

The aim of this study was to evaluate the fuel characteristics of thermally treated wood chips of the Larix kaempferi C. As torrefaction temperature was increased ($200^{\circ}C$ to $300^{\circ}C$), the carbon content, calorific value, and mass loss of torrefied wood chips increased significantly. The torrefied wood chips were shown to have hydrophobic properties even when only treated by mild torrefaction. The energy required to grind torrefied wood chips was reduced by the torrefaction process. Different sizes of wood chips were used in this study; however, this produced almost no difference in the fuel characteristics of processed Larix kaempferi C, except in the distribution of ground wood particles. Similar results were observed when the wood chips were torrefied for different lengths of time (15 min to 60 min) at a constant temperature. Torrefaction was shown to have positive effects on the fuel characteristics of Larix kaempferi C, including improved energy density, storage, and grindability.

• 한국정밀공학회지
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• 제14권2호
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• pp.58-65
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• 1997

Work rolls used in cold rolling mills must have outstanding wear resistance and very little plastic defor- mation. Thus, these rolls require a higher surface hardness and harding to a greater depth. To meet these requirements, the rolls, in general, have basic chemical composition of 0.7 to 1.0% carbon and 1.0 to 5.0% Cr(chromium), plus a small amounts of special elements, and are subjected to intensive water quenching and tempering at low temperature to provide a surface hardness of over 90 shore. This test results are as follows. Deflection and fracture load of 5% Cr material are than those of 3% Cr material and show flat curve from surface to subsurface. It will be clear that 5% Cr work roll has a superior resisti- bility against wear and abrasion comparing with 3% Cr work roll. The improvement of wear and abrasion in 5% Cr work roll will be achieved by the large amount of wpheroidal carbide. In grindability and polish, 5% Cr work roll will be a little inferior comparing with 3% Cr work roll.

• 공업화학
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• 제1권1호
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• pp.23-29
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• 1990

급속동결 전처리가 유기이온교환 수지의 분쇄에 미치는 효과를 연구하였다. 습윤상태의 이온교환 수지를 고체탄산 또는 액체질소를 이용하여 급속동결하면 이온교환 수지의 내부구조가 물리적으로 파괴되며 일단 파괴된 수지는 다시 실온이 되어도 원래의 상태로 회복되지 않음을 발견하였다. 따라서 급속동결한 수지는 실온에서도 분쇄가 매우 용이하며 이 효과는 양이온교환 수지가 음이온교환 수지에 비하여 더 크게 나타났다. 아울러 음이온교환 수지의 경우, 급속동결 전처리 효과 뿐만 아니라 이온종류 역시 분쇄에 큰 영향을 미침을 관찰할 수 있었다.

• 자원리싸이클링
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• 제24권6호
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• pp.31-37
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• 2015

철강산업 부산물 중 고로슬래그는 시멘트혼화재로 재활용되고 있지만 제강 슬래그들은 주로 골재로서 활용되고 있다. 본 연구는 전기로 산화슬래그를 대상으로 용융상태에서 철을 환원시켜 개질한 후 물로 급랭하여 제조된 비정질 슬래그를 시멘트 혼화재로 활용하고자 하였다. 개질된 전기로 산화슬래그는 고로수쇄슬래그 보다 분쇄성이 높았으며, 고로슬래그와 개질산화슬래그를 혼합하여 제조한 슬래그 시멘트의 모르타르 실험결과 고로슬래그에 대한 개질산화슬래그 대체율 20%까지는 비교시험체의 98%에 해당하는 압축강도 특성을 나타냈다.

• 산업기술연구
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• 제9권
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• pp.29-41
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• 1989

A general study on the upgrading of mica minerals which are mainly found in pegmatite deposits was carried out for the purpose of developing a technique for recovering mica in form of comercial grade products. By the way the grade one of about 5~6% $K_2O$ still is not developed. The target of this research work is to be establish a process for the efficient concentration of muscovite, containing more than 10% $K_2O$. The tests are applied to incraese the recovery and grade of concentrates in term of variations of conditions. The test sample consists of mainly muscovite and gangue mineral such as quartz, pyrite and chlorite. Decantation and shaking table tests were ineffective to up-grade this low grade one, but flotation method gave satisfactory result. By means of grade one, but flotation method gave satisfactory result. By means of grindability tests, an optimum result could be obtained from the sample ground to -48mesh feed size. The flotation result indicates that the dodecyl ammonium chloride used as a cationic collector is effective on the negatively charged surface, while the sodium dodecyl sulfate as an anionic collector is effective on the positively charged surface. Muscovite was floated by petroleum sulfonate as well as amine type collector, it also floated by MIBC as well as pine oil frother under well condition. Fine muscovite concentrates of about 10.68% $K_2O$ was obtained with 22.4% yield, by decantation, the muscovite concentrates of 10.10% $K_2O$ was obtained with 23.54% yield, by table concentration, the muscovite concentrates of 11.51% $K_2O$ was obtained with 23.0% yield by flotation.

• 한국세라믹학회지
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• 제51권6호
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• pp.584-590
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• 2014

Air-cooled slag showed grindability approximately twice as good as that of water-cooled slag. While the studied water-cooled slag was composed of glass as constituent mineral, the air-cooled slag was mainly composed of melilite. It is assumed that the sulfur in air-cooled slag is mainly in the form of CaS, which is oxidized into $CaS_2O_3$ when in contact with air. $CaS_2O_3$, then, is released mainly as $S_2O{_3}^{2-}$ion when in contact with water. However, the sulfur in water-cooled slag functioned as a constituent of the glass structure, so the$S_2O{_3}^{2-}$ ion was not released even when in contact with water. When no chemical admixture was added, the blended cement of air-cooled slag showed higher fluidity and retention effect than those of the blended cement of the water-cooled slag. It seems that these discrepancies are caused by the initial hydration inhibition effect of cement by the $S_2O{_3}^{2-}$ ion of air-cooled slag. When a superplasticizer is added, the air-cooled slag used more superplasticizer than did the blast furnace slag for the same flow because the air-cooled slag had higher specific surface area due to the presence of micro-pores. Meanwhile, the blended cement of the air-cooled slag showed a greater fluidity retention effect than that of the blended cement of the water-cooled slag. This may be a combined effect of the increased use of superplasticizer and the presence of released $S_2O{_3}^{2-}$ ion; however, further, more detailed studies will need to be conducted.

• Applied Biological Chemistry
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• 제28권3호
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• pp.115-123
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• 1985

보리의 건식제분공정을 확립키 위하여 수분함량 별 보리의 제분특성을 Brabender Grain Hardness Tester를 사용하여 조사하였다. 분말의 입자크기 별 적정 GHT간극은 -10+12mesh는 $1/0{\sim}1/10$, -12+18mesh는 $0/5{\sim}0/15$, -18mesh는 0/-15이었다. 수분함량에 따른 파쇄성은 수분함량이 감소할수록 증가하였으며 곡립경도는 반대양상을 나타내었다. 제분에 소요되는 에너지는 GHT간극이 작을수록, 수분함량이 증가할수록 큰값을 보였고 수분함량 14.04%에서 최대치를 나타내었다. 건조 소요에너지를 감안할 때 보리의 최적 건식제분조건은 수분함량 12.80%에서 GHT간극 0/-5일 때이었고 이때 1,000kg의 -18mesh 입자를 생산하는데 소요되는 에너지는 92.41kwh이었다.

• 에너지공학
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• 제28권1호
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• pp.1-9
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• 2019

석탄 화력발전소의 배연탈황공정에서 탈황용 흡수제로 사용하는 석회석을 대상으로 본드의 분쇄일지수(BWI) 및 하드그로브지수(HGI) 측정 후 분쇄효율을 비교하였다. 측정결과, 국내 탈황용 석회석의 분쇄성지수는 HGI가 증가함에 따라 BWI가 감소하는 선형적인 반비례 관계를 확인할 수 있었으며, 석회석의 화학조성 및 채광위치에 따른 결정구조에 따라 분쇄효율의 차이가 발생하였다. 이에 따라, 석회석의 분쇄성을 측정할 경우 측정방법이 까다롭고 시간이 오래 걸리는 BWI 보다 간편하게 측정할 수 있는 HGI를 활용하여도 시료의 분쇄성 차이를 확인할 수 있을 것으로 사료되며, 분쇄 특성에 따른 석회석의 선택적 활용 시 탈황효율 또한 향상시킬 수 있을 것으로 판단된다.