• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.243-250
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• 2010

Froth flotation of complex copper ore from Indonesia Jambi mine has been carried out to produce high-grade Cu concentrate. Since the ore contained minor Cu sulfides in addition to major Cu carbonate (malachite), copper concentrate was recovered by two-stage process of flotation, which consisted of copper sulfide flotation using xanthate followed by copper oxide flotation using oleic acid. The copper sulfide concentrate of 57.5% Cu grade with 9.5% recovery was obtained by copper sulfide flotation under conditions of 300 g/t collector (1 : 1 mixture of xanthate series Aero Promoter 211 and Aero Promoter 242) and pH 6.0 pulp. In subsequent copper oxide flotation on sink products, the concentrate of 30.8% Cu grade with 92.1% recovery was obtained under the conditions of oleic acid 300 g/t, AF65 50 g/t, pH 8.0 and 2 times cleaning. The flotation techniques which can achieve a Cu grade of 36.1% and a recovery of 92.1% have been developed from the two-stage process of flotation.

• Food Science and Preservation
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• v.22 no.5
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• pp.644-651
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• 2015

To enhance the consumption of horse meat, its nutritional composition was analyzed and compared to that of white meat (i.e., chicken and duck), which consumers consider healthy. Horse meat samples used in the experiment were classified by breed and grade as follows: Jeju horse (grade $1^+$ and 1), Jeju crossbred horse (grade 1 and 2), Thoroughbred (no grade), and cuts (loin, chuck roll, and arm picnic). In an analysis of general components and cholesterol, the horse meat was confirmed as a low-fat, high-protein, and low-cholesterol food material. In an amino acid analysis, horse meat contained a higher proportion of essential amino acids than white meat. The fatty acid compositions were also analyzed. The content of linolenic acid, an essential fatty acid, was significantly higher in all horse meat groups than in Ross chicken and Pekin duck meat. The content of palmitoleic acid showed similar results. In a mineral analysis, the levels of Fe and Zn in horse meat were higher than those of white meat. The mineral content was as follows except for the leg of shite meat: K > P > Na > Mg > Ca > Zn > Fe.

• Resources Recycling
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• v.21 no.5
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• pp.58-64
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• 2012

Ti button type ingots were prepared by recycling of Ti turning scraps using vacuum arc melting process for production of consumable arc electrode. The behavior of impurities such as Fe, W, O, and N in the Ti button ingots was investigated and the properties of the Ti button ingots were also evaluated. In the case of oxygen gaseous impurity, the oxygen layers on the surface of the Ti turning scraps were easily removed by the first vacuum arc melting. On the other hand, the solute oxygen in the Ti turning scraps was not removed by the next melting. In the case of Fe, major impurity in the Ti turning scraps, the removal degree in the final Ti button ingot refined by vacuum arc melting for 20 minutes was approximately 43 %, which is due to the vapor pressure difference between Ti and Fe. As a result, the Ti button ingots with ASTM grade 3 could be obtained by multiple vacuum arc melting from the Ti turning scraps. Therefore, it was confirmed that the preparation of consumable electrode for vacuum arc remelting could be possible by recycling of Ti turning scraps.

• Resources Recycling
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• v.14 no.1
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• pp.33-38
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• 2005

Worldwide magnesium market has been considerably growing recently due to adoption as light materials for automobile engines and electronic devices such as mobile phones. In this study, it is to prepare magnesium oxide, which is the first-step product in smelting of magnesium from the ore, using magnesite of Yongyanag mines in North Korea as raw ores. MgO grade of the magnesite was about 45 wt%, and SiO$_2$, CaO, Al$_2O_3$ and Fe$_2O_3$ were contained as impurities. The sample ore was crushed, classified and thermally analyzed to determine its calcination temperature. The sample of 45-75 ${\mu}m$ size was calcined at 600-900$^{\circ}C$, and effect of temperature on calcination and change of the particle shape was investigated. Optimum temperature of the calcination was about 750$^{\circ}C$, and 30 minutes was sufficient to obtain over 99% conversion. The purity of the calcined MgO was about 95 wt%.

• Economic and Environmental Geology
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• v.40 no.6
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• pp.771-784
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• 2007

This study shows the weathering characteristics of mica-schist affected by faulting and metamorphism through laboratory tests. Frozen-thaw test, which simulate the physical-chemical weathering processes in the laboratory, shows the important influence of foliation developed in mica-schist, resulting in $20{\sim}40%$ reduction of UCS according to weathering grade of rock. Slaking durability test was carried out for different weathering grade rock specimens and indicated that the specimens from fault area had a low durability index compared to other relatively fresh samples. XRD analysis allowed to estimate the dynamic evolution of mineral composition through wet-dry cycle in which the chlorite was the most important mineral leached out during slaking test. The creep test indicated that the main deformation produced along the foliation plane. The compacted clay minerals between discontinuity planes influence on the discontinuity shearing properties and result in a big difference between peak shear strength and residual strength. The results of laboratory tests on mica-schist show the possibility of a important deformation along the foliation plane or discontinuity.

• Journal of the Korean Ceramic Society
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• v.11 no.2
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• pp.22-30
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• 1974

This study was carried out to investigate the species of iron compounds in kaolin mineral and the bonding relation between the major kaolin and its subordinate iron compound existing as incidental mineral in common clay by means of chemical composition, X-ray diffraction, thermal differential and thermogravimetrie analysis for the application of clays in the field of ceramic raw material. The domestic clay are produced abounduntly in many places, but San-Cheong kaolin, Chu-An clay, and Yeong-Am clay were selected as samples in this experiment because of their frequent utilization in porcelain industry. Two kinds of samples with low and high iron content are picked up respectively from the place of production and elutriated under two micron size to determine the properties and concentration of iron compound very fine particles or colloidal substance of low crystalline grade. Therefore, hydrothermal treatment in autoclave was conducted considering the existence of low crystalline grade of iron compounds known as an amorphoue state in X-ray diffraction pattern furthermore, de-iron treatment of hydrothermal compound was done in order to identify the related iron compound before and after hydrothermal reaction and iron compound which is one of the samples was synthesized for the determination of their compounds state in more detail. The obtained results in this study are as follows: In San-Cheong kaolin, Chu-An clay and Yeong-Am clay 1) It is proved that species accompanying iron compound is $\alpha$-FeOOH form. 2) Iron compound is composed of very fine particles or colloidal substance. 3) The iron substance encircles the fine parts of clay minerals under 2 micron and acts as cementizing agent.

• Journal of the Korean Ceramic Society
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• v.15 no.4
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• pp.213-223
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• 1978

The purpsoe of this study was to produce domestic stamping materials; sling mass which could be used as unburned refractory for iron melt'ladle. Batch compositions were based on Belgian Ladelite; mineral compositions were composed of 84 wt% of quartz and 16 wt% of clay, and particle sizes were divided into 12 wt% of 1410/297㎛, 18wt% 297/149㎛, 20wt% of 149/74㎛, 11wt% 74/44㎛ and 39wt% 44㎛ under. The effect of variable batch compositions were also investigated such as substitution of pyrophylite or industrial grade alumina for quartz and of zircon for portion of quartz and clay, increase of clay and addition on sericite. Samples were pressed at 100kg/㎠ with 7.4wt% of water or 7.4wt% of 4 wt% PVA solution. Dried and Fired properties of samples such as linear shrinkage, apparent porosity, modulus of rupture, refractoriness and corrosion resistance to blast furnace slag were investigated. The results are summarized as follows. 1. Dried samples are shrinked, but fired at 700-1400℃ expanded. Samples fired at 700-1000℃ and 1200-1400℃ tended to expand with incresing of firing temperature, but fired at 1000-1200℃ tended to shrink with increase of firing temperature. 2. Apparent porosity of samples fired at 700℃ is increased, but fired at 1200-1400℃ decreased with increasing of firing temperature. 3. Modulus of rupture of samples fired at 700℃ is decreased, but fired at above 700℃ increased with increasment of firing temperature. 4. Dried samples with 7.4 wt% of 4 wt% PVA solution better improve modulus of rupture than with 7.4 wt% of water, but the firing strength of the sampels fired at 700-1000℃ is showed reversely. 5. In quartz-clay system, mineral phases of samples fired at above 1200℃ are consisted of α-quartz, α-cristobalite and mullite. Respectively as firing temperature was rising up, intensity of α-cristobalite and mullite is in creased. 6. Quartz-Kibushi clay system, Kimcheun quartz(substitutuion of portion of industrial grade alumina for quartz) Hampyeung clay system and pyrophyllite-clay system are better in corrosion resistance to blast furnace slag than burned pyrophyllite brick. 7. 84 wt% of pyrophyllite-16wt% of clay system is superior in modulus of rupture and corrosion resistance to blast furnace slag to 84 wt% of quartz-16 wt% of clay system.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.465-475
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• 2001

The purpose of this study was to evaluate effect of platelet rich plasma on the treatment of Grade II furcation involvement, with and without porous resorbable calcium carbonate($Biocoral^{(R)}$)in humans by digital subtraction radiography. 15 teeth(control group) were treated with porous resorbable calcium carbonate($Biocoral^{\(R)}$), and 15 teeth(test group) were treated with porous resorbable calcium carbonate($Biocoral^{(R)}$) and Platelet Rich Plasma. The change of bone density was assessed by digital subtraction radiography in this study. The change of mineral content by as much as 5%(vol) could be perceived in the subtracted images. The change of mineral content was assessed in the method that two radiographs are put into computer program to be overlapped and the previous image is subtracted by the later one. Both groups were statistically analyzed by Wilcoxon signed Ranks Test and Mann-whitney Test using SPSS program(5% significance level). The results were as follows: 1. In test group, the radiolucency in 3 months after surgry were significantly increased than 1 month after surgery(p<0.05). 2. In test group, there were no significant difference between 1 month after surgery and 6 months after surgery(p>0.05). 3. In test group, the radiopacity in 6 months after surgery were significantly increased than 3 months after surgery(p<0.05). 4. In control group, the radiolucency in 3 months and 6 months after surgery were significantly increased than 1 month after surgery(p<0.05). 5. In control group, the radiopacity in 6 months after surgery were significantly increased than 3 months after surgery(p<0.05). 6. There were no significant difference between test group and control group at 1 month, 3 months after surgery, but radiopacity in test group were significantly increased than control group at 6 months after surgery(p<0.05). In conclusion, Platelet Rich Plasma can enhance bone density.

• Journal of the Korean GEO-environmental Society
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• v.17 no.5
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• pp.17-25
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• 2016

The rocks exposed on the surface undergo expedite weathering process due to the effects of climatic process, etc. and the weathering process changes the properties of minerals, thereby lowering the stability of rocks. Therefore, it is important to examine the composition of minerals in order to investigate the resistance of rocks against weathering, which is performed by weathering sensitivity analysis. And microscopic flaking test was performed for the bored samples in this study and the composition of minerals that are vulnerable to weathering was measured through mode analysis. The lithological and mineralogical weathering factors were evaluated through this process. Furthermore, the degree of progress of weathering was identified by quantitatively measuring the actual mineral composition of rocks through X-Ray diffraction analysis and identifying the secondary minerals through observation with a scanning electron microscope. This analyzing the weathering sensitivity was analyzed to be capable of determining appropriate indicators that can determine weather resistance and predicting the weathering grade using chemical weathering speed.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.632-637
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• 2017

The vehicle lubricant occupies upto 35% in a total lubricant market and engine oil occupies upto 77% in the vehicle lubricant market in Korea. A suitable quality management of the circulating engine oil is necessary for driver and engine protection. But, KS and synthetic engine oil products (involved over 30% synthetic oil) are exempt to any quality management under Petroleum and Alternative Fuel Business Act. It is also known that synthetic oils such as PAO (poly alpha olefin) have excellent properties and performance like anti-wear, varnish control and oxidation stability than those of mineral oils. For this reason, PAO has been used for an engine oil, rotary screw and reciprocating compressor in addition to heavy duty and other extreme service applications. In this study, our research group analyzed the chromatogram pattern for the mineral oil, PAO and mineral oil involved a typical ratio of PAO using SIMDIST (simulated distillation). In the SIMDIST chromatogram, the mineral oil showed a broad peak, while PAO showed a sharp typical peak. Also the oil with a large viscosity grade exhibited a long retention time due to the heavy molecular weight and high boiling point. In particular, the blended mineral oil with 20% PAO sample showed a distinctly different pattern compared to that of using the conventional mineral oil. For monitoring PAO contents in distributing engine oils, we analyzed the SIMDIST for 27 kinds of engine oils which were popularly sold in Korea. The analytic results indicate that all kinds of engine oils showed that PAO contents were below 20% in engine oil products. Moreover, the PAO titled product was found to have a small amount of PAO. Thus, we conclude that the related laws for the proper quality management of synthetic oils are needed to be established.