• Resources Recycling
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• v.19 no.6
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• pp.93-101
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• 2010

In this study, we have studied hydration properties and compressive strength of the electric arc furnace reduction slag as a cement admixture. The reduction slag is mainly consisted of 17.1% of f-CaO and rapid curing clinker minerals, 37.1% of $C_{11}A_7CaF_2$, and 21.0% of $C_3A$. When the substitution rate of the slag on OPC was 30%, the initial setting time and final setting time has been shortened from 305 min. and 425 min. to 10min. and 30min. When the substitution rate of the slag on OPC was 7%, the compressive strength of mixed cement mortars has been increased than that of OPC during all period. When the substitution rate of the slag on OPC was over 20%, the compressive strength of mortars has been reduced than that of OPC at initial and final compressive strength. As a result of hydration properties of reduction slag, $C_{11}A_7CaF_2$ transfer to $C_3AH_6$ but as the substitution rate of slag on OPC increases, increased f-CaO and the metastable hydrates $C_4AH_{13}$ increased. Therefore, we should control the substitution rate of the slag on OPC was under 7% in order to use EAF reduction slag as a cement admixture.

• Journal of the Korea Institute of Building Construction
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• v.16 no.1
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• pp.1-7
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• 2016

In this research, it used cement powder and reduction slag, which generates high hydration heat in hydration reaction without heat cure below $-5^{\circ}C$ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction slag generates high hydration heat, compressive strength development is excellent. By generating highly hydration heat by $C_{12}A_7$ and $C_3A$ in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without $SO_3$, it is indicated that quick-setting occurs by shortage of $SO_3$. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, compressive strength developed 5MPa in 3 days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.

• Journal of the Korean Ceramic Society
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• v.50 no.5
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• pp.319-325
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• 2013

In this study, petroleum cokes ash and $C_{12}A_7$-based slag were used for the shrinkage reduction and strength enhancement of mortar. The hydration properties of shrinkage reduction agents were analysed. The flow, change of length and compressive strength were experimented with mortar-added shrinkage reduction agents. As a result of this study, petroleum cokes ash : $C_{12}A_7$-based slag = 60~80% : 20~40% showed excellent results. In the case of mortar with 20% $C_{12}A_7$-based slag, the setting time and change of length were similar to Ref. mortar. The flow and compressive strength were superior to Ref. mortar. In the case of mortar with a 40% $C_{12}A_7$-based slag, the setting time was longer than Ref. mortar. The compressive strength of 3 days and 7 days were superior to Ref. mortar.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.181-187
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• 2014

In order to use the spherical atomizing reduction steel slag (ladle furnace slag, LFS) instead of the fine aggregate of polymer concrete composites, various specimens were prepared with various replacement ratios of atomizing reduction steel slag and the addition ratios of polymer binder. Physical properties of these specimens were investigated through the absorption test, the compressive strength test, the flexural strength test, the hot water resistance test, the pore analysis and the micro-structure using scanning electron microscope. Results showed that the compressive strength and flexural strength of specimens with 7.5% of polymer binders increased with the increase of replacement ratios of atomizing reduction steel slag, but those of the specimens with 8.0% or more of polymer binders showed a maximum strength at a certain replacement ratio due to the material segregation causing the increase of fluidity. By hot water resistance tests, the compressive strength, flexural strength, average pore diameter, and bulk density decreased but the total pore volume and pore diameter increased. It was concluded that the amount of polymer binders could be reduced by maximum 23.8%, because the workability of the polymer concrete was remarkably improved by using the atomizing reduction steel slag instead of fine aggregate. However, since the use of atomizing reduction steel slag decreased the resistance of the polymer concrete to hot water, further studies are required.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.32-33
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• 2016

This purpose of this study is to find the properties of pore structure and length change of blast furnace slag cement added alkali powder stimulant on shrinkage reducing agent presence. In length change, the specimen added alkaline stimulant was smaller than normal blast furnace slag concrete. And the specimen added shrinkage reduction agent was confirmed to show smaller rate of length change than the length. In MIP analysis of 1day-age, 0.1㎛ subsequent pore amount of the specimen added alkaline stimulant was significantly smaller value the normal blast furnace slag concrete specimen.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.364-371
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• 2015

For the cost down of polymer concrete, It is very important to reduce the use amount of polymer binder, which occupies most of the production cost of polymer concrete. Fly ash and atomizing reduction steel slag are spherical materials obtained from industrial by-products. Spherical atomizing reduction steel slag was manufactured using steel slag from reduction process of ladle furnace by atomizing technology. To investigate the physical properties of polymer concrete, polymer concrete specimens were prepared with the various proportions of polymer binder and replacement ratios of atomizing steel slag. Results showed that compressive and flexural strengths of the specimens were remarkably increased with the addition amount of polymer binder and the replacement ratios of atomizing steel slag. In the hot water resistance test, compressive strength, flexural strength, bulk density and average pore diameter decreased but total pore volume and pore diameter increased. We found that polymer concrete developed in this study reduced the amount of polymer binder by 18.2% compared to the conventional product because of the remarkable improvement of workability of polymer concrete using spherical fly ash and atomizing reduction steel slag instead of calcium carbonate (filler) and river sand (fine aggregate).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.17-18
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• 2019

In this study, the initial strength reduction of coal gasification slag fine powders was confirmed through previous studies when used in cement formulations. It is also confirmed that the blast furnace slag is mixed with cementitious coal blast furnace slag, which is similar to coal gasification slag, to incorporate gypsum in order to prevent initial strength deterioration. In order to analyze the reactivity of coal gasification slag by desulfurization gypsum, the formation of hydrates and their reactivity at early ages were confirmed by electron microscope. In order to confirm the reactivity, the gypsum samples were prepared with unincorporated type and 2% mixed type. Experimental results showed that 2% of the desulfurized gypsum specimens reacted more actively than the uninjured ones.

• Resources Recycling
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• v.23 no.4
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• pp.69-74
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• 2014

Slags generated in the smelting reduction of deep sea manganese nodule could be utilized as an additional materials for making Fe-Si-Mn alloys by mixing with cokes and re-smelting at an arc furnace. In this re-melting process slag is also generated, and the secondary slag is treated as waste. In this survey, recycling of the waste slag of Mn nodule was studied. It is tried to utilize the waste slag as ceramic materials or construction materials. However, it is difficult to use the waste slag directly as an additional material to ceramics such as portland cement or castable refractory material due to the much difference of chemical compositions. As an altercation road constructing material is considered, and toxicity on the soil of the waste slag was tested according to Korean Standard for testing permissible amount of toxic substances. The test result was satisfied with the requirements on the standard. So, it should be suggested that the waste slag of the Mn nodule could be utilized as constructing materials such as road filler or base materials.

• Resources Recycling
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• v.19 no.1
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• pp.21-26
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• 2010

In order to understand the microwave carbothermic reduction of steelmaking slag to recover Fe, the effects of gas atmosphere and carbon addition on the carbothermic reduction behavior of CaO-$SiO_2$-FeO slag were investigated. It was found that the maximum temperature and the reduction rate were higher in air than in nitrogen atmosphere. In addition, under air atmosphere, the maximum temperature and the reduction rate were increased by increasing the amount of additive carbon. When the carbon equivalent is 5, the maximum temperature reached as high as 1800K and the reduction rate was approximately 90%. As the Carbon equivalent increased further, the maximum temperature and the reduction rate did not change.

• Resources Recycling
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• v.23 no.3
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• pp.30-36
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• 2014

A large amount of waste copper slag containing about 35 ~ 45% iron has been generated and discarded every year from pyrometallurgical processes for producing copper from copper concentrate. Thus, recovery of iron from the waste copper slag is of great interest for comprehensive use of mineral resource and reduction of environment problems. In this study, a physico-chemical separation process for upgrading iron from the waste copper slag discharged as an industrial waste has been developed. The process first crushes the waste copper slag below 1 mm (first crushing step), followed by carbon reduction at $1225^{\circ}C$ for 90 min (carbon reduction step). And then, resulting material is again crushed to $-104{\mu}m$ (second crushing step), followed by wet magnetic separation (wet magnetic separation step). Using the developed process, a magnetic product containing more than 66 wt.% iron was obtained from the magnetic separation under a magnetic field strength of 0.2 T for the waste copper slag treated by the reduction reaction. At the same conditions, the percentage recovery of iron was over 72%. The iron rich magnetic product obtained should be used as a iron resource for making pig iron.