레드머드 중화 방법에 따른 토양 중 비소의 안정화 특성 평가

우지오,김은정,Woo, Jio,Kim, Eun Jung 한국지하수토양환경학회 2021 지하수토양환경 Vol.26 No.6

Since the amount of red mud, generated from aluminum smelting process as a by-product, has increased worldwide, the recycle and metal resource recovery from the red mud is becoming more important. In this study, in order to recycle the red mud as a soil stabilizer to remediate arsenic contaminated soils, neutralization of red mud was investigated. Red mud was neutralized by washing with distilled water and NaCl, CaCl₂, FeCl₃, and HCl solutions and heating at 200-800℃, and arsenic stabilization characteristics in soils were evaluated with the neutralized red mud. Although washing with distilled water was not effective in neutralizing red mud, the application of the washed red mud to soils lowered the soil pH compared to the application of untreated red mud. Among NaCl, CaCl₂, FeCl₃, and HCl solutions, washing with FeCl₃ showed the most effective in lowering pH of the red mud from pH 10.73 to pH 4.26. Application of the neutralized red mud in soils resulted in quite different arsenic stabilization efficiency depending on soil samples. In M1 soil, which showed relatively high arsenic stabilization efficiency by untreated red mud, the neutralization of red mud resulted in little effect on arsenic stabilization in soil. On the other hand, in M2 soil, which showed low arsenic stabilization efficiency by untreated red mud, the neutralization of red mud increased arsenic stabilization significantly. Soil characteristics such as clay minerals and pH buffering capacity seemed to affect reactions between red mud and soils, which resulted in different effects of the red mud application on soil pH and arsenic stabilization efficiencies.

Red mud를 이용한 중금속 Cd 및 Pb의 흡착제거 특성

임수빈(Yim Soobin),김재곤(Kim Jaegon),송호철(Song Hocheol) 한국지반환경공학회 2011 한국지반환경공학회논문집 Vol.12 No.7

본 연구에서는 red mud를 흡착제로 이용하여 산성광산배수내 대표적인 유해 중금속인 Cd과 Pb의 흡착특성을 파악하고, 산처리와 소성처리 방식으로 활성화된 red mud에 의한 Cd와 Pb의 중금속 흡착능의 변화를 알아보고자 하였다. Red mud에 대한 Cd과 Pb의 흡착은 반응시간 30분 이내에 대부분 발생하였으며, 5시간 경과 후에는 평형상태에 도달하는 것으로 나타났다. pH가 증가할수록 red mud에 대한 Cd 및 Pb의 흡착은 증가하는 것으로 나타났다. Red mud를 증류수 혹은 산으로 중화 처리하거나 산처리 혹은 소성처리 등과 같은 활성화 처리할 경우 Cd와 Pb에 대한 red mud의 흡착능은 오히려 감소하는 것으로 나타났으므로 red mud를 이용한 Cd와 Pb의 흡착제거는 가공하지 않은 원 상태의 red mud를 이용하는 것이 효과적인 것으로 파악되었다. Red mud에 대한 Cd와 Pb의 흡착거동은 Langmuir 및 Freundlich 등온흡착모델에 모두 잘 적용되었으며, Red mud 흡착제에 대한 Langmuir 등온흡착식의 qm 과 Freundlich 등온흡착식의 KF 상수값은 Cd에 대하여 각각 5.230㎎/g와 1.118㎎/g이었으며 Pb에 대해서는 각각 22.222㎎/g와 7.241㎎/g의 값을 나타내고 있었다. The objective of this study is to investigate the removal characteristics of cadmium(Cd) and lead(Pb) by adsorption on red mud and to study the adsorption characteristics of Cd and Pb using red mud activated by acid treatment and calcination. Theadsorption of Cd and Pb on red mud was significantly achieved within 1hour and equilibrated after 5 hours. The adsorption capacity of Cd and Pb on red mud increased with increasing pH. The neutralization of red mud by distilled water or acid and the activation of red mud by acid treatment or calcination decreased the adsorption capacity of Cd and Pb on red mud, suggesting that Cd and Pb could be effectively eliminated by adsorption on red mud without any pretreatment or modification. Both Langmuir and Freundlich models were successfully applied to describe the adsorption behavior of Cd and Pb on red mud. The qm of Langmuir adsorption model and KF of Freundlich adsorption model were 5.230㎎/g and 1.118㎎/g for Cd and 22.222㎎/g and 7.241㎎/g for Pb, respectively.

액상 및 중화 레드머드를 첨가한 시멘트 페이스트의 수화특성

강혜주 ( Kang Hye Ju ),강석표 ( Kang Suk Pyo ) 한국건축시공학회 2020 한국건축시공학회 학술발표대회 논문집 Vol.20 No.2

Red mud is a highly alkaline waste by-product of the aluminum industry. Although recycling of red mud is being actively researched, a feasible technological solution has not been found yet. In this study, we propose that neutralization of red mud alkalinity could assist in its use as a construction material. Neutralized red mud ( pH 6-8) was prepared by adding sulfuric acid to liquefied red mud (pH 10-12). After adding liquid and neutralized red mud to the cement paste, the heat of hydration was measured. As a result of the experiment, the calorific value of the cement paste with liquid red mud was lowered and delayed compared to the cement paste with neutralized red mud.

황산 중화 액상레드머드를 사용한 슬래그 시멘트 모르타르의  수화 특성

강석표,박규은,김상진 대한건축학회 2024 대한건축학회논문집 Vol.40 No.1

본 논문에서는 알루미늄 제조공정의 부산물인 레드머드 슬러지를 재활용하기 위해 액상레드머드와 황산 중화 액상레드머드를 제조하고, 이를 슬래그 시멘트 모르타르에 적용하여 건축 재료로서의 활용 가능성을 검토하였다. 액상레드머드와 황산 중화 액상레드머드를 슬래그 시멘트 모르타르로 대체한 결과, 초기 응결 시간이 단축하고 초기 강도를가 향상되는 긍정적인 영향을 미치는 것으로 나타났다. 특히, 레드머드에 황산을 첨가하면 NaOH와 반응하여 Na2(SO4)3 형태의 화합물이 생성되는데, 이는 황산 중화 액상레드머드를 첨가한 슬래그 시멘트 모르타르의 급결 현상을 저하시키는 요인으로 작용하여 28일 강도 결과에서 액상레드머드 첨가 슬래그 시멘트 모르타르 보다 높은 강도를 나타내었다. XRD 분석 결과에서는 새로운 A 피크로 Xonotlite와, B 피크로 Gismondite가 확인되었으며, 이는 초기 압축강도 결과에 영향을 미치는 것으로 나타났다. 따라서 레드머드 슬러지를 활용한 황산 중화 액상 레드머드는 건설산업에서의 활용성이 높은 것으로 판단된다. In this paper, liquid red mud and sulfuric acid neutralized liquid red mud were manufactured to recycle red mud sludge, a by-product of thealuminum manufacturing process, and applied to slag cement mortar to examine the possibility of its use as a building material. Liquid redmud and sulfuric acid neutralization As a result of replacing liquid red mud with slag cement mortar, it was found to have a positive effectby shortening the initial setting time and improving initial strength. In particular, when sulfuric acid is added to red mud, it reacts withNaOH to produce a compound in the form of Na2(SO4)3, which acts as a factor in reducing the rapid setting phenomenon of slag cementmortar added with sulfuric acid-neutralized liquid red mud, reducing the 28-day strength. The results showed higher strength than slag cementmortar added with liquid red mud. In the XRD analysis results, Xonotlite and Gismondite were identified as the new A peak and Gismonditeas the B peak, which appeared to affect the initial compressive strength results. Therefore, it is believed that sulfuric acid neutralizationliquid red mud using red mud sludge has high utility in the construction industry.

Engineered biochar composite fabricated from red mud and lipid waste and synthesis of biodiesel using the composite

Yoon, Kwangsuk,Jung, Jong-Min,Cho, Dong-Wan,Tsang, Daniel C.W.,Kwon, Eilhann E.,Song, Hocheol Elsevier 2019 Journal of hazardous materials Vol.366 No.-

<P><B>Abstract</B></P> <P>Co-pyrolysis of lipid waste and red mud was investigated to achieve valorization of red mud by fabricating biochar composite. For the further sustainable approach, this study intentionally employed carbon dioxide (CO<SUB>2</SUB>) as reaction medium in the co-pyrolysis process. The use of CO<SUB>2</SUB> on co-pyrolysis of lipid waste and red mud enabled manipulation of the carbon distributions between pyrogenic products. CO<SUB>2</SUB> expedited the thermal cracking of lipid waste and further reacted with lipid waste during the thermolysis. These mechanistic roles of CO<SUB>2</SUB> were catalytically enhanced by the presence of mineral phases (Fe<SUB>2</SUB>O<SUB>3</SUB>) in red mud, thereby resulting in the enhanced formation of CO (40 times more at 550 °C). However, CO<SUB>2</SUB> suppressed dehydrogenation of lipid waste (∼ 50%), which resulted in the different pathway for reducing iron oxide in red mud. Moreover, as an aspect of valorization of red mud, catalytic capability of biochar composite was evaluated. As a case study, biodiesel (FAMEs) were synthesized, and all experimental findings suggested that biochar composite could be an effective catalyst for biodiesel synthesis. As compare to biodiesel synthesis using silica (92% yield at 360 °C), the equivalent biodiesel yield was achieved with the biochar at much lower temperature (130 °C).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Valorization of red mud and lipid waste via the thermo-chemical process. </LI> <LI> Enhanced energy recovery in the thermo-chemical process using CO<SUB>2</SUB>. </LI> <LI> Fabrication of biochar composite from red mud and lipid waste. </LI> <LI> Biodiesel synthesis using biochar composite. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

시멘트 페이스트의 강도특성에 미치는 중화 레드머드의 영향

강혜주 ( Kang Hye Ju ),강석표 ( Kang Suk-pyo ) 한국건축시공학회 2020 한국건축시공학회 학술발표대회 논문집 Vol.20 No.1

In this study, as a measure to recycle red mud, which is a byproduct of the Bayer Process, red mud was manufactured as liquid and recycled without drying and grinding. Previous studies have shown that mechanical performance decreases when liquid red mud is applied to cement concrete. Therefore, in this study, liquid red mud was neutralized with nitric acid and applied to cement paste to examine the properties of cement paste according to the addition of red mud. As a result, the compressive strength of 10% liquid red mud decreased by 37.7% compared to Plain, and 10% liquid red mud indicates similar strength to Plain and restores the strength.

황산으로 중화시킨 액상레드머드 첨가 슬래그시멘트 모르타르의 특성

김상진 ( Kim Sang-jin ),강석표 ( Kang Suk-pyo ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.2

In this paper, the characteristics of slag cement mortar added with neutralized liquid red mud with sulfuric acid and reduced pH were reviewed to improve the strength degradation of cement concrete added with liquid red mud. As a result, in the case of compressive strength up to 7 days, the strength of the cement mortar added with liquid red mud tends to increase compared to Plain. This shows that adding liquid red mud to cement mortar tends to increase the initial age strength, and the compressive strength on the 28th shows 74% of Plain when adding non-neutralized liquid red mud and 89% when adding sulfate neutralized red mud. Therefore, it is judged that the compression strength is improved by neutralizing the liquid red mud with sulfuric acid.

질산으로 중화시킨 액상레드머드 첨가 슬래그시멘트 모르타르의 특성

김상진 ( Kim Sang-jin ),강석표 ( Kang Suk-pyo ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.2

In this paper, the characteristics of slag cement mortar added with neutralized liquid red mud with nitric acid to reduce pH by neutralizing liquid red mud with nitric acid were reviewed to improve strength degradation of cement concrete added with liquid red mud. As a result, the compressive strength of cement mortar added with liquid red mud was higher than that of Plain on 1 and 3 days, and the strength of red mud neutralized with nitric acid was lower than that of cement mortar added with liquid red mud on 7 days, but the strength was recovered on 28th. It was found that the addition of red mud has the effect of improving the strength in the early age.

Synthesis of structural binder for red brick production based on red mud and fly ash activated using Ca(OH)₂ and Na₂CO₃

Kim, Soon Yong,Jun, Yubin,Jeon, Dongho,Oh, Jae Eun Elsevier 2017 Construction & building materials Vol.147 No.-

<P><B>Abstract</B></P> <P>This paper explored the effectiveness of red mud and a mixture powder of Ca(OH)<SUB>2</SUB> (C), Na<SUB>2</SUB>CO<SUB>3</SUB> (N), and fly ash (F) (denoted CNF powder) as precursor materials to produce an environment-friendly high strength brick product. Overall, despite the inclusion of up to ∼81% of red mud and fly ash, 7-day strengths were developed ∼17–34MPa; this was high enough to be used as a structural binder for brick production. In particular, the use of NaOH was very effective in increasing flowability, and, more importantly, early strength in the red mud-CNF blended system, despite the red mud inclusion, because NaOH greatly improved the degree of reaction of the system, resulting in more calcium silicate hydrates (C-S-H) formation as well as significant pore size refinement at early days of curing. Trial bricks were also prepared to examine possible toxicity due to the inclusion of red mud and fly ash using the toxicity characteristic leaching procedure (TCLP) test and the TCLP concentrations were very low.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Red mud and cementless CNF binder were explored as precursor for brick production. </LI> <LI> Up to ∼81% of red mud and fly ash inclusion, 7-day strengths were ∼17–34MPa. </LI> <LI> The use of NaOH increased flowability and early strength in this binder system. </LI> <LI> NaOH greatly improved the degree of reaction, resulting in more C-S-H formation. </LI> </UL> </P>

레드머드 대체율에 따른 폴리머 혼입 알칼리활성화 슬래그 - 레드머드 시멘트모르타르의 강도 및 기공특성

권성준,강석표 한국구조물진단유지관리공학회 2016 한국구조물진단유지관리공학회 논문집 Vol.20 No.2

The alkali–slag–red mud(ASRC) cement belongs to clinker free cementitious material, which is made from alkali activator, blast-furnaceslag(BFS) and red mud in designed proportion. This study is to investigate strength and pore characteristics of alkali-activated slag cement(NC), clinkerfree cementitious material, and ordinary portland cement(C) mortars using polymer according to red mud content. The results showed that the hardenedalkali-activated slag-red mud cement paste was mostly consisted of C-S-H gel, being very fine in size and extremely irregular in its shape. So the hardenedASRC cement paste has lower total porosity, less portion of larger pore and more portion of smaller pore, as compared with those of hardened portlandcement paste, and has higher strength within containing 10 wt.(%) of alkali-activated slag cement(NC) substituted by red mud. 알칼리활성화 슬래그-레드머드 시멘트는 알칼리활성화 시멘트 연구의 일환으로서 시멘트 조성에서 알칼리자극제, 고로슬래그와레드머드로 구성되어져 있으며, 포틀랜트 시멘트를 사용하지 않는 클링커 프리 시멘트(Clinker Free Cement)를 의미한다. 본 논문에서는 포틀랜트 시멘트를 전혀 사용하지 않고 고분자 유기화합물인 재유화형 분말 폴리머를 혼입한 알칼리활성화 슬래그 시멘트에 레드머드의 대체율을달리하여 강도특성, 기공특성 등을 기존 포틀랜트 시멘트와 비교 평가하였다. 그 결과 알칼리활성화 시멘트에 레드머드를 대체할 경우 C-S-H광물상과 에트린가이트가 주요 수화생성물로 포틀랜트 시멘트와 비교하여 조직이 치밀하고 대체율 10%까지는 압축강도 및 휨강도가 증가하였다.