제강 슬래그는 제철 공정 중 쇳물에 녹아있는 불순물을 제거하는 공정에서 발생하는 슬래그로, 불순물과 생석회(CaO), 석회석(CaCO3) 등과의 반응으로 생성된다. 슬래그의 발생량은 원료 및 공정에 따라 그 차이가 있으나 1톤 조강 시 약 470kg이 발생하며, 국내 제강 슬래그의 발생량은 한 해 약 830만톤 정도이다. 제강슬래그에는 칼슘의 성분이 다량으로 함유되어 있어 콘크리트 등 건설원료로 사용이 가능하지만, 이를 사용하기 위해서는 장시간의 숙성 과정이 필요하기 때문에 처리 및 재활용할 수 있는 방안이 필요하다. 광물탄산화는 산업폐기물을 이용하여 이산화탄소 고정 및 탄산염을 생성하는 기술로, 이를 제강 슬래그에 적용하는 연구가 진행되고 있다. 본 연구에서는 광물탄산화 방법중의 하나인 간접 탄산화 방법을 통해 제강 슬래그로부터 탄산칼슘을 제조하고 그 특성을 평가하였다. HCl을 이용하여 제강 슬래그 내 칼슘을 추출하였으며, NaOH 및 CO2 가스를 이용하여 탄산칼슘을 제조하였다. 추출의 경우 반응 온도에 의한 효과는 크지 않은 반면, HCl 농도 및 고액비의 영향을 받았으며, HCl의 농도가 높을수록 낮은 순도의 탄산칼슘이 생성되었다. 최적 조건에서 칼슘 추출 효율은 89%로 나타났으며, 98% 이상의 순도를 가진 탄산칼슘을 생성하는 것이 가능하였다.

Carbonation is one of the most critical deterioration phenomena to concrete structures exposed to high CO2 concentration, sheltered from rain. Lots of researches have been performed on evaluation of carbonation depth and changes in hydrate compositions, however carbonation modeling is limitedly carried out due to complicated carbonic reaction and diffusion coefficient. This study presents a simplified carbonation model considering diffusion coefficient, solubility of Ca(OH)2, porosity reduction, and carbonic reaction rate for low concentration. For verification, accelerated carbonation test with varying temperature and MIP (Mercury Intrusion Porosimetry) test are carried out, and carbonation depths are compared with those from the previous and the proposed model. Field data with low CO2 concentration is compared with those from the proposed model. The proposed model shows very reasonable results like carbonation depth and consuming Ca(OH)2 through reduced diffusion coefficient and porosity compared with the previous model.

This paper reported the effect of blended activator on the compressive strength of alkali-activated slag cement(AASC) mortar. The alkalis combinations made using sodium hydroxide(NaOH), calcium hydroxide(Ca(OH)2) and potassium hydroxide(KOH) with calcium carbonate(CaCO3). The compressive strength was increase as the dosage of caustic alkali increase.

Chloride adsorption is very ambiguous in the mechanisms of deterioration of concrete exposed to marine environment. Author suggested that chloride adsorption with cement hydrates depends on pH value of pore solution. However, adsorbed chloride ions can be dissolved in concrete under the combined deterioration environment of carbonation and chloride penetration. In the condition, the most crucial issue is the amount of dissolved chloride ions in cement paste due to carbonation. In this study, dynamics experiment was designed to quantify the effect of CaCO3 on chloride adsorption. Based on the experiment results, the final goal of this study is to develop integrated system for predicting chloride adsorption /desorption behaviors.

This study investigated the textural changes after the calcium-pectin bonding of ginseng roots and their vinegar and calcium solution immersion. The strength and breakdown of the ginseng roots increased according to the increase in the calcium carbonate concentration, with the highest in the 0.7~1.0% calcium carbonate. The hardest and softest ginseng roots were obtained in the 1.0% calcium carbonate concentration. The strength, brittleness and hardness of the ginseng roots that were soaked in 1% calcium carbonate and 5~6% acidity vinegar continued to increase with the long-term storage of the ginseng root drink. The softness of the ginseng root that was dipped in 5% acidity vinegar with 1.0% calcium carbonate decreased with the long-term storage of the ginseng root drink. Thus, calcium and vinegar immersion of ginseng roots could prevent softening and clouding during the long-term storage of the ginseng root drink.

This study is about a kind of organic waste, food waste, and was conducted by using an alternative medium for the cultivation of oyster mushrooms to examine applicability. The study investigated the cultivation characteristics for major cultivated varieties of oyster mushrooms and the growth characteristics within food waste mediums. In addition, NaCl desalinization of food waste is being pointed out as a problem when using the medium, therefore, the effects of the medium's composition were examined by using calcium carbonate. Calcium carbonate is used for desalinization of NaCl. This study investigated the use of a total of 6 cultivars of the oyster mushroom, the Suhan (PL.1), Chiak No. 5 (PL.2), Chiak No. 7 (PL.3), Samgu No. 5 (PL.4), Samgu No. 8 (PL.5), Jangan No. 5(PL.6). In terms of medium, the optimum growth of the mycelium of the oyster mushroom was observed in the PDA medium. The optimal culture conditions was pH 6.0 in Samgu No. 8 (PL. 5) and pH 5.5-6.6 in another cultivar. In terms of food waste, the mycelium’s growth were investigated and found insufficient in the bulk of cultivars. but Chiak No. 7 (PL.3) was superior to that of other cultivars relative to the mycelium’s growth. (Mycelium’s growth: Chiak No. 7 (PL.3) = Jangan No. 5 (PL.6) > Samgu No. 8 (PL.5) > Samgu No. 5 (PL.4) > Suhan (PL.1) > Chiak No. 5 (PL.2)). In the test of desalinization using Calcium carbonate, the early salt concentration was 4.3%. When treating the calcium carbonate (1 ~ 10%) in the food waste, a change of salt concentration less than 5% of the calcium carbonate could be observed. Also, when treating the calcium carbonate (1 ~ 10%, w/w) in the food waste medium, a great change of EC could not be observed either. Therefore, the addition of calcium carbonate to food waste does not affect the growth of the mushroom, thus we had to speculate about the possibility of using food waste in the cultivation of oyster mushrooms.

도심에 위치한 탄산염암 석조문화재는 주로 대기 오염으로 인하여 흑색층이 형성되어 있으며 심하게 손상되어 있는 상태이다. XRF, XRD, SEM 등의 분석을 통하여 도심에 위치한 석탑 표면에 형성된 흑색층의 화학조성, 구성광물, 미세조직에 대해 연구하였다. 또한 흑색층이 원암에 끼치는 영향을 밝히고, 나아가 안정환동위원소분석법을 적용하여 흑색층 내에 함유되어 있는 황성분의 기원을 밝혔다. 석탑 원암의 구성광물은 방해석이지만 흑색층은 석고와 소량의 석영을 포함하고 있다. 흑색층을 구성하는 다량의 석고는 석탑 내부에 균열을 생성시키는 원인 물질이며, 흑색층과 원암의 경계면은 흑색을 띠는 것은 아니지만 그 특성이 흑색층과 유사하여 대기오염 물질을 쉽게 흡착하여 흑화될수 있다는 것을 보여주었다. 안정황동위원소분석 결과 흑색층에 함유되어 있는 황의 주 기원이 다를 수 있음이 밝혀졌다.

In the present paper, batch and semi-continuous settling characteristics of a binary calcium carbonatewater system were investigated. Using experimental data of batch settling characteristics, a graphical analysis for a semi-continuous thickening column was developed and compared with experimental results on the basis of Kynch theory, only where the feed velocity line was within the limits of Kynch theorem Ⅲ. The analysis showed good agreement with experiments. Quite erroneous results, however, was observed for the analysis of a sludge region on the underloaded operation, which was considered due to the deviation from the limits of theory.