• The Korean Journal of Ceramics
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• 제2권3호
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• pp.125-130
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• 1996

Hematite iron ore and waste iron oxide sludge containing about 3-5 wt% $SiO_2$ were purified by three types of method developed on the basis of the Bayer process which is known as the purification process of bauxite ore. The basic principle of the developed methods lies in the fact that the impurities contained in the iron oxides, such as $SiO_2$ and $Al_2O_3$ are soluble in the alkaline reagents. Reaction of the raw materials with KOH was done in pressure vessel, at atmospheric pressure, and by both of these two. By the pressure vessel method $SiO_2$ content was reduced to below 0.5 wt% in the waste iron oxide sludge, while, in iron ore, $SiO_2$ remained at 2-3 wt%. The atmospheric pressure reaction rendered the waste iron oxide sludge $SiO_2$ content below 0.5wt% when the reaction temperature increased to above 90$0^{\circ}C$. The combined method of two previous methods was the most effective process and rendered the refined iron oxide about 300-400ppm of $SiO_2$. Using some refined iron oxides, Ba-ferrite was produced and magnetic properties were measured. The highest quality of magnetic properties obtained in this study were Br=2.09 G, bHc=1.99 KOe, iHc=4.54 KOe, $(BH)_{max}$=1.06 MGOe. Effect of sintering condition and chemical composition will be discussed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.49-52
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• 2007

We investigated hydrogen storage and production properties using redox system of iron oxide($Fe_{3}O_{4}$ + $4H_{2}$ ${\leftrightarrows}$ 3Fe + $4H_{2}O$) modified with rhodium, ceria and zirconia under atmospheric pressure. Reduction of iron oxide with hydrogen(hydrogen storage) and re-oxidation of reduced iron oxide with steam(hydrogen evolution) was carried out using a temperature programmed reaction(TPR) technique. On the temperature programmed studies, the effects of amounts of cerium and zirconium on the re-oxidation rate of partial reduced iron oxides were increased with increasing metal additives amount, but the rhodium amount showed little effect on the re-oxidation rate. On the thermal studies, the re-oxidation rates were enhanced with increasing temperature(300 $^{\circ}C$ < 350 $^{\circ}C$).

• 한국결정성장학회지
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• 제11권4호
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• pp.176-179
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• 2001

Iron oxide powders were prepared under high temperature (up to $175^{\circ}C$) and pressure conditions( up to 129 pasi) by precipitation from metal nitrates with aqueous potassium hydroxide. Various types of iron oxide powders were obtained at different conditions. The size and the shape of the particles can be controlled as afunction of starting solution pH. The average particles size of the synthesized iron oxide powders increased, the particle shapes of the powders became fibrous, and the crystalline phase of the powder changes from iron oxide to iron hydroxide with increasing solution pH. The effects of synthesis parameters are discussed.

• 한국분말재료학회지
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• 제20권3호
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• pp.180-185
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• 2013

The iron oxides nanoparticles and iron oxide with other compounds are of importance in fields including biomedicine, clinical and bio-sensing applications, corrosion resistance, and magnetic properties of materials, catalyst, and geochemical processes etc. In this work we describe the preparation and investigation of the properties of coated magnetic nanoparticles consisting of the iron oxide core and organic modification of the residue. These fine iron oxide nanoparticles were prepared in air environment by the co-precipitation method using of $Fe^{2+}$: $Fe^{3+}$ where chemical precipitation was achieved by adding ammonia aqueous solution with vigorous stirring. During the synthesis of nanoparticles with a narrow size distribution, the techniques of separation and powdering of nanoparticles into rather monodisperse fractions are observed. This is done using controlled precipitation of particles from surfactant stabilized solutions in the form organic components. It is desirable to maintain the particle size within pH range, temperature, solution ratio wherein the particle growth is held at a minimum. The iron oxide nanoparticles can be well dispersed in an aqueous solution were prepared by the mentioned co-precipitation method. Besides the iron oxide nanowires were prepared by using similar method. These iron oxide nanoparticles and nanowires have controlled average size and the obtained products were investigated by X-ray diffraction, FESEM and other methods.

• 폴리머
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• 제29권3호
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• pp.266-270
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• 2005

Fe(CO)$_5$(철-펜타카보닐)의 열분해법을 이용하여 산화철 나노 입자를 제조하였다. 표면 조절 시약으로서 생체적 합성 고분자인 폴리(비닐피롤리돈)(PVP)을 사용하여 산화철 나노 입자의 크기를 제어하였다. 산화철 나노 입자의 형성 여부는 XRD를 통해 분석하였으며, PVP 코팅된 산화철 나노 입자의 크기는 TEM, ELS를 통하여 분석하였다. PVP 코팅 된 산화철 나노 입자의 입자 크기는 PVP/Fe(CO)$_5$의 몰비와 용매, PVP 분자량에 의해 조절되었다. PVP 함량이 증가함에 따라 입자 크기가 증가하였으며 디메틸포름아마이드를 용매로 하였을 때 $50\~100$ nm의 산화철 나노 클러스터가 형성되었고, Carbitol을 용매로 하였을 때 균일하게 분산된 10 nm 이하의 작은 PVP 코팅된 산화철 나노 입자가 형성되었다. 본 연구에서 제조된 PVP코팅된 산화철 나노 입자는 물에 잘 분산될 뿐 아니라 생체적합적인 PVP로 코팅이 되었기 때문에 in vivo에 응용할 수 있으며, 입자의 크기가 $50\~100$nm및 10 nm로 조절됨으로써 MRI 조영제로서 가능성을 가지고 있음을 확인하였다.

• 자원리싸이클링
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• 제9권5호
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• pp.22-27
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• 2000

철강산업 냉연공장에서 산세공정중 발생하는 산화철은 대부분 전자재료용과 안료용 원료로 사용되고 있다. 특히 산화철중에는 여러 불순물이 포함되어 있는데 최근에는 염소성분 저감을 통한 고품질화가 요구되고 있다. 본 연구에서는 실제로 냉연공장 산화수설비에서 배소로의 조업조건을 변경하며 산화철종 염소성분 제거실험을 하였으며, 산화수설비 배소로 후단에 탈염소장치를 설치하고 산화철의 탈염소 현장실험을 실시하였다. 실험결과 산화수설비 배소로의 현장 조업 범위내에서 산화철중 염소성분은 최대 1.100ppm으로 저감 가능 하였으며, 배소로에 부착한 탈염소 실험장치에서는 최대 360ppm 으로 저감 가능하였다.

• 한국물환경학회지
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• 제20권2호
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• pp.104-109
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• 2004

Removal of nutrients from domestic sewage or industrial wastewater is needed to protect surface waters from eutrophication. This research was carried out to remove the nitrogen (N) and phosphorus (P) from the wastewater using the iron oxide obtained from the steel industry and the natural zeolite, respectively. This research was conducted in both batch and continuous systems. The removal efficiency of the nutrients was evaluated in the batch system using the varying concentrations of zeolite and iron oxide added. The removal efficiency of N was 60% at the 8g of zeolite added. In the same condition, the removal efficiencies of N were 76% and 82% at 12g and 16g of zeolite added, respectively. Removal efficiency of P was 80% as 8g of iron oxide was added. The removal efficiency of P was correspondingly increased as the concentration of iron oxide was increased. Continuous column system was also used to evaluate the removal efficiency of N and P by the addition of zeolite and ferric oxide, respectively. Removal efficiencies of N were compared in the mixed packing, two stage, and four stage columns, respectively. The removal efficiencies (80%) of N in the separate packed columns (two and four stages) were higher than the mixed packing column (400%) after 90 hr. Whereas, the removal efficiencies of P were similar to each other in the three columns.

• 공업화학
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• 제24권6호
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• pp.656-662
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• 2013

원자력발전소의 2차 계통수 중에 존재하는 철산화물(magnetite)은 열전달 튜브의 표면에 침착(fouling)되어 열전달 성능을 떨어뜨리거나 부식을 유발한다. 이와 같은 문제를 방지하기 위해, 원전 2차 계통수 중에 고분자 분산제(polymeric dispersant) 주입을 통해 철산화물의 분산 안정성 향상을 도모하는 연구를 수행하였다. 카르복실기(-COOH, carboxyl group)를 함유한 3종의 음 이온성 고분자(PAA, PMA, PAAMA)를 선정하였으며, 이들에 농도변화(1~1000 ppm)에 의한 마그네타이트 분산 특성을 평가하기 위해 침강시험, 투과율 측정, 입도 측정, 제타전위 측정을 수행하였다. 고분자 분산제는 수용액 중 철산화물 분산안정성에 큰 영향을 미쳤다. 분산제가 주입되면 분산 안정성이 향상되는 경향을 보였으나, 분산제 농도 증가에 따라 마그네타이트의 분산 안정성이 선형적으로 비례하여 증가하지 않았다. 이는 임계 분산제 농도 이상에서는 철산화물 사이의 응집(agglomeration)이 발생하기 때문인 것으로 사료된다. 분산안전성 향상 효과는 분산제-철산화물의 농도비(ppm, 분산제/마그네타이트)가 0.01~0.1 범위에서 현저하였다. 분산제 주입을 통한 철산화물 제거 효과를 최대화하기 위해서는 적용 환경 특성, 철산화물 농도, 분산제 농도 및 철산화물-분산제 농도비의 최적화가 필요한 것으로 판단된다.

• 자원리싸이클링
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• 제12권6호
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• pp.19-25
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• 2003

제철소 냉연 공정의 염산 폐액에서 ruthner process 공법으로 제조된 산화철을 사용하여 2차 배소 온도변화에 따른 산화철의 분체 특성을 조사하였고, 산화철과 스트론튬을 건식 혼합 및 가소후 Sr-ferrite 자석을 제조하여 자기적 물리적 특성을 조사하였다. Ruthner proces의 산화철을 2차 배소를 실시한 경우, Cl- 함량이 적고 분체 특성이 안정적인 배소온도는 $800^{\circ}C$ 부근으로, 평균 입자(APS)는 1.5 $mu extrm{m}$, apparent bulk density(ABD)는 1.4 g/$m\ell$ 이며, Cl- 함유량은 0.05% 이하를 나타내었다. Ruthner process에서 제조된 산화철을 vibrating disk mill에서 1차 분쇄를 실시한 경우, Sr-ferrite magnet의 보자력(HcJ)은 229 kA/m에서 251 kA/m로 향상하였다. Sr-ferrite magnet의 소결 온도 변화에 따른 잔류자속밀도와 보자력의 희귀식은 Br≒-0.258HcJ＋494의 함수 관계를 나타내고 있으며, 성형 중 가한 자장 방향과 수직방향에 따른 수축비는 산화철의 2차 배소 온도 $800^{\circ}C$까지는 1.6으로 안정적인 판상형으로 결정 성장을 나타내고 있으나, 그 이상의 온도로 2차 배소한 산화철을 사용한 경우에는 소결에서 결정이 더 커진 것으로 판단된다.

• Carbon letters
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• 제11권2호
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• pp.117-121
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• 2010

The composites of alginate, carbon nanotube, and iron(III) oxide were prepared for the removal of heavy metal in aqueous pollutant. Both alginate and carbon nanotube were used as an adsorbent material and iron oxide was introduced for the easy recovery after removal of heavy metal to eliminate the secondary pollution. The morphology of composites was investigated by FE-SEM showing the carbon nanotubes coated with alginate and the iron oxide dispersed in the alginate matrix. The ferromagnetic properties of composites were shown by including iron(III) oxide additive. The copper ion removal was investigated with ICP AES. The copper ion removal efficiency increased greatly over 60% by using alginate-carbon nanotube composites.