• Title, Summary, Keyword: $CaCO_3$ 제조

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The Extraction of Ca in Electric arc Furnace Slag for CO2 Sequestration (CO2고정화(固定化)를 위한 전기로제강(電氣爐製鋼)슬래그의 칼슘성분(成分) 침출(浸出))

  • Youn, Ki-Byoung
    • Resources Recycling
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    • v.22 no.1
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    • pp.64-71
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    • 2013
  • Mineral carbonation has been proposed as a possible way for $CO_2$ sequestration. The electric arc furnace slags consist of calcium, magnesium and aluminum silicates in various combinations. If they could be used instead of natural mineral silicates for carbonation, considerable energy savings and $CO_2$ emissions reductions could be achieved. Indirect aqueous carbonation of the slags consists of two steps, extraction of calcium and carbonation. Acetic acid leaching of electric arc furnace slags had been already studied to extract Ca in them, but it was reported that the carbonation of the extracted $Ca^{2+}$ in the leached solution would suffer from too slow kinetics, even at high pressure of $CO_2$. In this work, to develop more efficient extraction of the electric arc furnace slags, hydrochloric acid leaching to separate calcium from them was studied, and the results were compared with the acetic acid ones. The phase boundary between $Ca^{2+}$ and $CaCO_3$ in the solution with pH was determined by thermodynamic calculations. Hydrochloric acid was more effective than acetic acid for the extraction of Ca in electric arc furnace slag, and there is a possibility to recycle an unreacted hydrochloric acid in the leached solution by electrolysis or evaporation.

Development of Fluorite-free Desulfurizing Agent for Molten Iron using Al-dross and Ladle Slag (알루미늄 드로스와 래들 슬래그를 활용한 무형석 용선 탈황제 개발)

  • Lee, Chang-Hyun;Koo, Yeon-Soo;Lee, Man-Seung
    • Resources Recycling
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    • v.27 no.5
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    • pp.49-53
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    • 2018
  • In developing an optimum steelmaking process, the purity of the product, environmental impact, capability and cost of the process should be considered. Desulfurization of molten iron is conducted during preliminary treatment stage before converter operation. Although fluorite is added as a desulfurizing agent in CaO and $CaCO_3$ based agents, the concentration of fluorine in slag is strictly regulated. In order to develop desulfurizing agent without fluorine, CaO was mixed with Al dross and ladle slag containing alumina. The characteristics and desulfurizing capacity of the CaO based desulfurizing agent thus prepared were tested by varying temperature of Kanvara Reactor. Our results showed that the desulfurizing capacity of the samples prepared in this work was found to be similar to that of the traditional desulfurizing agents with fluorine.

Fabrication and Properties of $(Pb_{1-x}C_{ax})((Co_{\frac{1}{2}}W_{\frac{1}{2}})_yTi_{1-y})O_3+(MnO_2, NiO)$ piezoelectric ceramic (압전세라믹 $(Pb_{1-x}C_{ax})((Co_{\frac{1}{2}}W_{\frac{1}{2}})_yTi_{1-y})O_3+(MnO_2, NiO)$)

  • Mun, Dong-Jin;Do, Si-Hong;Jang, Ji-Won
    • The Journal of the Acoustical Society of Korea
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    • v.6 no.4
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    • pp.55-63
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    • 1987
  • Modified $PbTiO_3$ piezoelectric ceramics added with 0.2, 0.25, 0.3 mol of $CaCO_3$ and 0.04 mol of $(Co_{\frac{1}{2}}W_{\frac{1}{2}})$ and 0.05 mol of $MnO_2$ and NiO have been fabricated. These ceramics can be poled sufficiently within 10 minutes at $100^{\circ}C$ under about d.c. field of 40 kv/cm. Detailed measurement was performed on dielectric constants, cutie temperatures, elastic and piezoelectric properties and coupling factors for the fabricated ceramics. The most value of the piezoelectric coupling factors was coupling factor of thickness mode kt and its value for 0.25 mol of Ca was about $45\%$. Dielectric constants of $\varepsilon_{33}^T$ and $\varepsilon_{11}^T$ for 0.25 mol of Ca were 242 and 260, and coupling factor ratio (kt/Kp) and Qm were 6 and 357 respectively.

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A Study of Calcium Phosphate Crystal Phases Prepared from Oyster Shells (굴 껍질로부터 제조된 calcium phosphate 결정상에 관한 연구)

  • Ryu, Su Chak
    • Korean Journal of Materials Research
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    • v.13 no.4
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    • pp.246-250
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    • 2003
  • Calcium phosphate was prepared by chemical reaction formula using Oyster shells and $H_3$$PO_4$solutions. After added to 0.1 M∼0.9$ M H_3$$PO_4$ solution for oyster shell, prepared powders were investigated for heating properties and formation phase with heat treatment temperatures. As the results of XRD analysis of heated powders at $500^{\circ}C$$1200^{\circ}C$,$ CaCO_3$ phases were observed at the temperature of below 900 TEX>$^{\circ}C$ and in the condition of 0.1 M∼0.9 M $H_3$$PO_4$ solutions. However, $CaCO_3$, $CaPO_3$(OH) and $Ca_3$($PO_4$)$_2$ phases were appeared at the temperature range between $500∼900^{\circ}C$ and in the solution of 0.7 M to 0.9 M $H_3$$PO_4$. $Ca_{ 5}$($PO_4$)$_3$(OH) and CaO phases due to the decarbonation of oyster shells($CaCO_3$) were appeared at above $1000^{\circ}C$ and in the solution of below 0.5 M $H_3$X$PO_4$. However in the case of above 0.7 M $H_3$$H_4$ solutions, $Ca_{5}$ ($PO_4$)$_3$(OH) was decomposed into $Ca_3$($PO_4$)$_2$ at more higher 100$0^{\circ}C$. Thus $Ca_3$(X$Ca_4$)$_2$ phases were appeared at higher than 100$0^{\circ}C$.

Deactivation causes of dry sorbents for post-combustion CO2 capture (연소 후 이산화탄소 포집용 흡수제의 비활성화 원인 규명)

  • Cho, Min Sun;Chae, Ho Jin;Lee, Soo Chool;Jo, Seong Bin;Kim, Tae young;Lee, Chul Ho;Baek, Jeom-In;Kim, Jae Chang
    • Korean Chemical Engineering Research
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    • v.57 no.2
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    • pp.253-258
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    • 2019
  • Several materials are used to design the sorbents applied in a fast-fluidized bed process for post-combustion $CO_2$ capture. In this study, $K_2CO_3$-based dry sorbent (KMC) was prepared by using Micro-cell C (MCC), one of the materials used to design the sorbent, and then its $CO_2$ sorption and regeneration properties were evaluated. KMC sorbent showed a low $CO_2$ capture capacity of 21.6 mg $CO_2/g$ sorbent, which is about 22% of the theoretical value (95.4 mg $CO_2/g$ sorbent) even at 1 cycle, and showed a low $CO_2$ capture capacity of 13.7 mg $CO_2/g$ sorbent at 5 cycles. It was confirmed that the KMC sorbent was deactivated due to the formation of a $K_2Ca$ $(CO_3)_2$ phase, resulting from the reaction of the $K_2CO_3$ with the Ca component contained in the MCC. In order to solve the deactivation of sorbent, and KM8 sorbent was prepared by adding the process of calcining the MCC at $850^{\circ}C$. The KM8 sorbent showed a high $CO_2$ capture capacity of 95.2 mg $CO_2/g$ sorbent and excellent regeneration property. Thus, it was confirmed that the deactivation of the sorbent could be solved by adding the calcining step to remove the side reaction causing material.

Effect of Solvent on the Dispersion Stability of CaCO3 Pigment (CaCO3 안료의 분산 안정성에 대한 용제의 영향)

  • Lee, Gun Dae;Ryu, Young Cheal;Suh, Cha Soo;Hong, Seong Soo;Ahn, Byung Hyun;Moon, Myung Jun
    • Applied Chemistry for Engineering
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    • v.8 no.2
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    • pp.252-261
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    • 1997
  • The effect of solvent on the dispersion stability of $CaCO_3$ pigment in various solvents and resin solutions has been studied using Dynometer. Dispersion stability can be estimated in a relatively short time by means of Dynometer and the solubility parameter, ${\delta}$, of $CaCO_3$ determined from dispersion stability was 11.62(${\delta}_d=8.04$, ${\delta}_p=5.05$, ${\delta}_h=6.70$). The solvent showing weaker interaction with pigment increased the adsorption of resin on to the pigment, resulting in higher dispersion stability in resin solution. It was found that the rheological properties and dispersion stability of pigmented resin solution were depending strongly on the solvent added in small amount in the formulation.

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Purification of Waste Acid and Manufacture of Complex Oxide and Mn-Ferrite Powder by Co-Roasting Process (폐산의 정제 기술 및 분무 배소법에 의한 복합 산화물과 Mn-Ferrite 분말의 제조)

  • 유재근;김정석;민병구;성낙일
    • Resources Recycling
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    • v.7 no.4
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    • pp.64-75
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    • 1998
  • The purpose of this study is to produce high putity composite powder composed of Fe-oxide, Mn-oxide and Mn-ferrite having superior homogencity in composition and particle size distribution by co-roasting process. Binary component metal (Fe, Mn) chloride solutions were produced by dissolving mill scale and ferro-mangancse alloy in hydrochloric acid. These chloride solutions contained the impurities such as SiO$_{2}$, P, Al, Ca and Na, which were originated from the Fe/Mn source materials. The neutralization and polymeric coagulant method were adoped to refine the hydrochloric liquor. When pH is far below the isoelectric point (pH 2-3), the SiO$_{2}$ was the most effectively reduced element, while other impurities remained unchanged. By increasing pH above 3, most of the impurities could be reduced effectively due to the coprecipitation reaction. The polymeric coagulants such as poly vinyl alcohol, resin amine and ammonium molybdate were found to have no effect on the spray roaster designed by the authors. The produced oxide powders were confirmed to be mixtures of Fe-oxide, Mn-oxide and mn-ferrite. the powders were homogeneously mixed and the particle size increased sleeply with increasing co-roasting temperature.

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A study on the surface modification of artificial lightweight aggregates by using bottom ash from coal power plant (화력발전소 바닥재를 이용한 인공경량골재의 표면개질에 관한 연구)

  • Ryu, Yug-Wang;Kim, Yoo-Taek
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.4
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    • pp.208-213
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    • 2009
  • Artificial lightweight aggregates were produced by using bottom ashes and dredged soils from coal power plant. The amount of glassy phases on the aggregate surfaces, specific gravities, absorption rates, and observations of cross-sectional surfaces were compared according to the compositions, sintering temperatures, and the amount of coating. It is concluded that surface modification by 10 % $CaCO_3$ coating on the aggregate surfaces enhances the properties of aggregates as follows: Specific gravities were controlled by depressing formation of large pores in the aggregates. Sticking phenomena among aggregates during the sintering process was drastically decreased by reducing glassy phases on the aggregate surfaces. Pumping problems during the application of ready-mix concretes containing lightweight aggregates having high value of absorption rates could be solved by reducing the absorption rate.

Effect of Surface Modification and Additives on Nitridation of Al-AlN System (Al-AlN계 질화반응에 대한 표면개질 및 첨가제의 영향)

  • 유재영;김용남;황명익;박정현
    • Journal of the Korean Ceramic Society
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    • v.40 no.3
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    • pp.249-254
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    • 2003
  • AI, AIN and additives such as Li$_2$CO$_3$, Y$_2$O$_3$ and CaCO$_3$ which promoted nitridation were mixed, formed and heat-treated in nitrogen atmosphere. The effect of solvent, additive and temperature on nitridation of AI-AIN system was studied. When ethanol containing 1 wt% oleic acid was used as a mixing solvent, the formation of oxide was minimized due to surface modification of AI and AIN particles. The addition of Li$_2$CO$_3$ or CaCO$_3$ as an additive extremely diminished the formation of oxide which formed during heat treatment for nitridation compared with the addition of Y$_2$O$_3$.