소각바닥재의 재활용 현황과 염화물이 환경에 미치는 영향

안지환,임미희 한국자원공학회 2009 한국자원공학회지 Vol.46 No.1

In this paper, we have reviewed the effect of chloride on the environment to emphasize the need of chloride removal from municipal solid waste incineration (MSWI) bottom ash. Recycling technologies of the bottom ash are focused on minimizing concentrations of contaminants in the ash prior to the manufacture of products to prevent their leaching into the environment. It has been shown that the MSWI bottom ash in Korea contains a large amount of soluble or insoluble chlorides. Although chloride does not affect human health, high concentration of chloride in the environment affects negatively growths of plants and aquatic organisms. It also decreases the diversity of soil microorganisms and changes the composition of soil microbial community. Soil inorganic chloride is related to chlorination of soil organic matter (humic substances), mediated by microorganisms and exoenzymes. Moreover, chloride may increase the mobility of toxic heavy metals from the soil by forming strong complexes with them. Therefore, it is important to understand the effect of chloride on the environment and to develop technologies for chloride removal. 본고에서는 도시생활폐기물 소각바닥재에 함유된 염소 제거의 필요성을 강조하기 위해 염소가 환경에 미치는 영향들에 대해 조사하였다. 도시생활폐기물 소각바닥재의 재활용 기술은 오염물질이 환경에 유출되는 것을 방지하기 위해 제품으로의 생산 이전에 바닥재에 함유된 유해물질농도를 감소시키는 것에 초점을 맞추고 있다. 특히 한국의 도시생활폐기물 소각바닥재에는 다량의 용해성 또는 난용해성 염화물이 함유된 것으로 밝혀졌다. 염화물은 인체에 특별한 영향을 미치지는 않지만 환경에 유출된 고농도의 염화물은 식물과 수중 생물의 성장에 악영향을 미친다. 또한 염화물은 토양 미생물 다양성을 감소시키고 토양 미생물 군집 조성을 변화시킨다. 토양의 무기 염화물은 미생물 생체 효소를 매개로 하여 토양유기물질(humic substances)을 염소화시키는 것에 관여하기도 한다. 뿐만 아니라 토양에서 이동성이 큰 염화물은 토양에 흡착하고 있는 독성 중금속들과 강한 복합체를 형성하면서 토양에서 지하수로 중금속의 이동성을 증가시키기도 한다. 이와 같이 염화물이 토양 및 물 환경에 미치는 영향을 이해하고 그 제거를 위한 기술 개발에 노력을 기울일 필요가 있다.

철-니켈 합금 에칭구액 용매추출 공정 용액으로부터 고순도 탄산니켈 제조에 관한 연구

채병만,황성옥,이석환,김득현,이상우,김대원,최희락,Chae, Byung-man,Hwang, Sung-ok,Lee, Seok-Hwan,Kim, Deuk-Hyeon,Lee, Sang-Woo,Kim, Dae-Weon,Choi, Hee-Lack 한국결정성장학회 2017 韓國結晶成長學會誌 Vol.27 No.6

여러 가지 금속을 에칭하기 위하여 사용된 $FeCl_3$ 폐용액은 유가금속인 니켈을 함유하고 있다. 본 연구에서는 염화철을 재생하고 남은 니켈 함유 에칭폐액으로부터 니켈을 고순도의 탄산니켈 결정분말로 회수하고자 하였다. 5 % NaOH 수용액을 이용하여 pH 4의 조건에서 1차적으로 철 성분의 불순물을 약 97 % 제거하고 추가적으로 남은 불순물을 제거하기 위하여 용매추출제 D2EHPA(Di-(2-ethylhexyl) phosphoric acid)를 사용하여 불순물로서 존재하는 금속이온들을 약 99% 제거하였다. 그 후 불순물이 제거된 염화니켈 용액에 탄산나트륨과의 반응을 통하여 99.9 % 이상의 순도를 가진 탄산니켈분말을 얻을 수 있었다. The $FeCl_3$ waste solution used to etch various metals contains valuable metal such as nickel. In this study, we recovered as high purity nickel carbonate crystalline powders from nickel-containing etching waste solution after regeneration of iron chloride. Firstly we eliminated about of the iron impurities under the condition of pH 4 using 5 % NaOH aqueous solution and then removed the remaining impurities such as Ca, Mn and Zn etc. by using solvent extractant D2EHPA (Di-(2-ethylhexyl) phosphoric acid). Thereafter, nickel carbonate powder having a purity of 99.9 % or more was obtained through reaction with sodium carbonate in a nickel chloride solution.

원심분리를 통한 음식물쓰레기 바이오차의 탈수 특성

안광호,김이태,이예은,신동철,정진홍,정윤아 한국수처리학회 2022 한국수처리학회지 Vol.30 No.2

Various methods of technology for using food waste as energy have been developed, but their utility as fuel is low due to the salt concentration contained in food waste. As of 2019, the daily amount of domestic food waste is approximately 14,000 tons, and as the amount of food waste increases, it is necessary to develop technology for processing a large amount of food. Bio-char made from food waste can be a good fuel with high calorific value if salt is removed. In this study, a centrifugal separator was used to remove chloride ions from bio-char, and as a result of the experiment, the higher heating value(HHV) was improved through centrifugation. Food waste bio-char showed higher calorific value as the particle size was smaller, and higher calorific value was improved by 15~25% after centrifugation than before centrifugation. As for the chlorine component removal efficiency before and after centrifugation, the smaller the particle size, the higher the chloride ion removal efficiency. After centrifugation, the moisture of bio-char was 21.7~30.4%, and the ultimate analyzes of bio-char were found the most in the order of carbon, oxygen, hydrogen, and nitrogen, and no sulfur component was detected. As a result of water quality analysis, the dewatering water after centrifugation showed the degree of contamination of sewage was shown.

시멘트 염소 함량과 콘크리트의 슬럼프, 압축강도 간의 상관관계 연구

김경석(Kyoung-Seok Kim),서동균(Dong-Kyun Seo),우지완(Ji-Wan Woo),최재원(Jae-Won Choi),유병노(Byeong-Know You) 한국건설순환자원학회 2024 한국건설순환자원학회 논문집 Vol.12 No.2

본 연구에서는 콘크리트 슬럼프 및 압축강도와 시멘트 염소 함량을 포함한 기타 요인과의 상관관계에 대해 통계적으로 분석하였다. 시멘트 염소 함량은 236 ~ 794 ppm 범위로 선정했으며, 기타 물성들은 KS L 5201 규격에 만족하는 시멘트를 사용하였다. 분석결과, 어떠한 요인들과도 초기 슬럼프와는 상관관계가 존재하지 않았다. 슬럼프 경시변화에서의 염소 성분은 강한 음의 상관관계를 나타내고 있으며, 1일 ~ 7일 압축강도에서는 강한 양의 상관관계를 갖고 있는 것으로 분석되었다. 한편, 28일 압축강도에서는 염소성분과 압축강도 간의 상관성이 없는 것으로 확인되었다. This study was analyzed the relationship between concrete slump, compressive strength and other factors such as the quantity of chloride or others using statistics method. The amount of chloride in cement was selected to range from 236 to 794 ppm, and cement that satisfied the KS L 5201 standard for other physical properties was used for this experiment. As a result, no factors had a interrelationship for initial slump and the strong-negative correlation between concrete slump elapsed time and the quantity of chloride. The proportion of chloride was shown as a strong-positive correlation for compressive strength from 1-day to 7-day curing. However, there was no correlation between chloride and compressive strength at 28-day curing.

염화알칼리에 의한 과열기 소재의 고온부식 영향

김범종,정수화,김혜수,류창국,이은도 한국청정기술학회 2018 청정기술 Vol.24 No.4

In order to cope with environmental problems and climate change caused by fossil fuels, renewable energy supply is increasing year by year. Currently, waste energy accounts for 60% of renewable energy production. However, waste has a lower calorific value than fossil fuels and contains various harmful substances, which causes serious problems when applied to power generation boilers. In particular, the chlorine in the waste fuel increases slagging and fouling of boiler heat exchangers, leading to a reduction in thermal efficiency and the main cause of high temperature corrosion, lowering facility operation rate and increasing operating cost. In this study, the high temperature corrosion experiments of superheater materials (ASME SA213/ASTM A213 T2, T12 and T22 alloy steel) by alkali chlorides were conducted, and their corrosion characteristics were analyzed by the weight loss method and SEM-EDS. Experiments show that the higher the temperature and chloride content, the more corrosion occurs, and KCl further corrodes the materials compared to NaCl under the same condition. In addition, the higher the chromium content of the material, the better the corrosion resistance to the alkali chlorides. 화석연료로 인한 환경문제 및 기후변화 대응을 위해 신재생에너지 공급비중은 매년 증가하고 있으며 현재 폐기물 에너지는신재생에너지 생산량의 60% 가량을 차지하고 있다. 그러나 폐기물은 화석연료에 비해 낮은 발열량을 가지고 여러 유해물질이 포함되어 있어 발전용 보일러에 적용 시 다양한 문제를 발생시킨다. 특히 연료 내 염소성분은 보일러 열교환부에 슬래깅 및 파울링을 증가시켜 열효율 감소와 고온부식의 주요 원인이 되며 설비 가동률을 낮추고 운전비용을 증가시킨다. 본 연구에서는 염화알칼리에 의한 과열기 소재의 부식특성 분석을 위해 과열기용 주요 금속소재(ASME SA213/ASTM A213 T2, T12 and T22 합금)를 대상으로 고온부식 실험을 수행하고 무게 감량법과 주사전자현미경 에너지분산분광기(SEM-EDS)를활용해 다양한 조건에 따른 부식특성을 분석하였다. 실험 결과 온도 및 염화물 함량이 높을수록 부식이 증가하였으며 NaCl 보다 KCl의 부식성이 더 높음을 확인하였다. 또한 소재의 크롬함량이 높을수록 염화알카리에 대한 내부식 특성이 우수하게나타났다.

유리 연마슬러지를 혼입한 콘크리트의 복합열화 저항성에 관한 실험적 연구

이현기,오홍섭,심종성,지광습 한국방재학회 2013 한국방재학회논문집 Vol.13 No.2

Subsidiary concrete structures such as a barrier and a side-channel suffer from rapid deterioration due to the excessive use of an de-icing in Korea. Consequently, the needs for replacement and/or repair of the structures has increased significantly, resulting in the increase of the maintenance cost. The preliminary study strongly indicates that it is necessary to improve the durability and visibility of the subsidiary structures in order to reduce the maintenance cost of the structures. Hence, the purpose of this research project is to develop a concrete with high durability by incorporating waste-glass or polymer admixture in concrete. And in order to develop concrete of high durability by utilizing waste glass, a research was focused on an effect of waste glass sludge mixing over concrete strength and durability and measurement for compression strength by each material age performed together with chloride ion penetration resistance and scaling resistance test for properties of multi-deterioration. 국내 콘크리트 방호벽, 측구와 같은 소구조물들은 과도한 제설제의 사용에 의해 복합열화의 피해를 받고 있으며, 구조물의 유지보수비 절감과 안전성 향상을 위해 콘크리트 소구조물의 내구성 증진이 요구되는 상황이다. 따라서 본 연구의 목적은 폐유리를 활용한 고내구성 콘크리트 개발하는 것이다. 이에 따라 폐유리를 활용한 고내구성 콘크리트 개발을 위해 폐유리 혼입에 따른 콘크리트 강도 및 내구성의 영향에 초점을 맞추었으며, 먼저, 재령별 압축강도 시험을 수행하였으며, 복합열화 특성을 확인하기 위하여 염화물 확산계수 시험과 박리저항성 시험을 실시하였다.

A reactive distillation process for the treatment of LiCl-KCl eutectic waste salt containing rare earth chlorides

Eun, H.C.,Choi, J.H.,Kim, N.Y.,Lee, T.K.,Han, S.Y.,Lee, K.R.,Park, H.S.,Ahn, D.H. Elsevier 2016 JOURNAL OF NUCLEAR MATERIALS Vol.480 No.-

<P><B>Abstract</B></P> <P>The pyrochemical process, which recovers useful resources (U/TRU metals) from used nuclear fuel using an electrochemical method, generates LiCl-KCl eutectic waste salt containing radioactive rare earth chlorides (RECl<SUB>3</SUB>). It is necessary to develop a simple process for the treatment of LiCl-KCl eutectic waste salt in a hot-cell facility. For this reason, a reactive distillation process using a chemical agent was achieved as a method to separate rare earths from the LiCl-KCl waste salt. Before conducting the reactive distillation, thermodynamic equilibrium behaviors of the reactions between rare earth (Nd, La, Ce, Pr) chlorides and the chemical agent (K<SUB>2</SUB>CO<SUB>3</SUB>) were predicted using software. The addition of the chemical agent was determined to separate the rare earth chlorides into an oxide form using these equilibrium results. In the reactive distillation test, the rare earth chlorides in LiCl-KCl eutectic salt were decontaminated at a decontamination factor (DF) of more than 5000, and were mainly converted into oxide (Nd<SUB>2</SUB>O<SUB>3</SUB>, CeO<SUB>2</SUB>, La<SUB>2</SUB>O<SUB>3</SUB>, Pr<SUB>2</SUB>O<SUB>3</SUB>) or oxychloride (LaOCl, PrOCl) forms. The LiCl-KCl was purified into a form with a very low concentration (<1 ppm) for the rare earth chlorides.</P>

혼화재로서 폐유리 미분말을 사용한 콘크리트의 특성 평가

최성우 ( Choi Sung-woo ),류득현 ( Ryu Deug-hyun ),김준형 ( Kim Jun-hyoung ) 한국건축시공학회 2017 한국건축시공학회 학술발표대회 논문집 Vol.17 No.1

In the automotive industry, such as scrap metal and plastic scrap process is being recycled. Although the glass beads are used as road paving or other additives and processing crushing, recycling is known that there are limits. The utilization of waste glass was evaluated as a concrete admixture by using powder characteristics and chemical composition of the glass. As a result of using waste-glass powder as an admixture, it is difficult to expect the pozzolanic effect, but it is found that it can increase the fluidity of concrete and ensure the durability performance in the appropriate amount range.

Subcritical water leaching of valuable and hazardous metals (Ni, Co, and Cd) from waste Ni-Cd batteries using ferric chloride hexahydrate (FeCl_3.6H₂O)

( Md Ishtiaq Hossain Khan ),( Masud Rana ),( Theoneste Nshizirungu ),( Jeong Hun Park ) 한국폐기물자원순환학회 2022 ISSE 초록집 Vol.2022 No.-

Many valuable metals may be found in waste Ni-Cd batteries. The leaching of valuable metals from waste Ni-Cd batteries has attracted tremendous attention in recent years. In spite of this, it remains difficult to develop a sustainable and efficient method. The purpose of this study was to investigate an efficient, convenient, and innovative way to recycle valuable metals from waste Ni-Cd batteries. Heavy metals from Ni-Cd batteries were leached in subcritical water using ferric chloride hexahydrate (FeCl₃.6H₂O). By releasing HCl in subcritical water, ferric chloride hexahydrate (FeCl₃.6H₂O) accelerates metals' leaching performance. Ni, Cd, and Co leaching efficiencies were also extensively studied using reaction parameters, such as temperature, time, solid-to-liquid ratio, and Ni-Cd powder-to-FeCl₃.6H₂O mass ratio. FT-IR, XRD, SEM-EDS, and XPS analyses were carried out on solid residues obtained after subcritical water leaching experiments. The leachate was analyzed by ICP-OES. In the optimized conditions, Ni, Cd, and Co leached with almost (93, 95, and 100) % efficiency; at 300°C, 120 minutes, 15g/L solids/liquids ratio, and 1:3 Ni-Cd-to-FeCl₃.6H₂O mass ratios. For the recovery of valuable metals from waste Ni-Cd batteries, the subcritical water leaching has been found to be efficient, environmentally friendly, and sustainable method.

강도수준별 순환골재 콘크리트의 염화물 확산특성

이준,이봉춘,조영근,정상화 한국구조물진단유지관리공학회 2016 한국구조물진단유지관리공학회 논문집 Vol.20 No.2

This paper presents mechanical properties and chloride diffusivity of the recycled aggregate concretes(RAC) in which natural coarse aggregatewas replaced by recycled coarse aggregate(RCA) by compressive strength levels(20, 35, 50 MPa). A total of 9 RAC were produced and classified intothree series, each of which included three mixes designed with three compressive strength levels of 20 MPa, 35 MPa and 50 MPa and three RCAreplacement ratios of 0, 50 and 100%. Engineering properties of RAC were tested for slump test, air content, compressive strength, chloride penetrationdepth and chloride diffusion coefficient. The test results indicated that the workability of RAC could be improved or same by RCA replacement ratios,when compared with that containing no RCA. This is probably because of the RCA shape improving the workability of RAC. Also, the test resultsshowed that the compressive strength was decreased by 9~10% as the RCA replacement ratios increase. Furthermore, the result indicated that themeasured chloride diffusion coefficient increases by 144% with the increase of the RCA replacement. In the case of the concrete having low levelcompressive strength, the increase of chloride diffusion coefficient tends to be higher when using the RCA. However, the trend of chloride diffusioncoefficient in high level compressive strength concrete is similar to that obtained in general concrete. This is because that the effect of the RCA replacementcould be a decrease with increase of compressive strength. Therefore, an advance on the admixture application and mix ratio control are required toimprove the chloride resistivity when using the recycled aggregate in large scale. 본 연구에서는 국내에서 생산되고 있는 콘크리트용 순환 굵은골재를 사용하여 콘크리트의 압축강도 수준(20, 35, 50 MPa)에 따라순환 굵은골재의 혼입률 변화가 콘크리트의 염화물 확산특성에 미치는 영향을 분석하였다. 실험결과 순환 굵은 골재의 치환율 변화에 따른 유동성(슬럼프)은 순환골재를 혼입하지 않은 경우에 비해 동등하거나 양호한 유동성을 나타내는 것으로 나타났다. 이러한 영향은 국내에서 생산되는 순환골재의 양호한 입형이 유동성 개선에 기여한 것으로 판단된다. 또한, 순환 곩은 골재의 치환율 변화에 따른 압축강도는 순환골재 혼입률이 증가할수록 약 9~10% 감소하는 것으로 나타났다. 그리고 염화물 확산계수는 순환골재 혼입률이 증가함에 따라 최대 144%까지 증가하는 결과를 나타냈으며 낮은 강도 수준의 콘크리트 일수록 순환골재 활용에 따른 내염성 저하 정도가 큰 것으로 나타났다. 강도가 증가할수록 순환골재 혼입에 따른 영향은 감소되어, 고강도 영역에서는 일반 콘크리트와 유사한 염화물 확산 특성을 발현하는 것으로 분석되었다. 따라서 순환골재를 콘크리트용 재료로 대량 활용하기 위해서는 콘크리트의 내염성 개선을 위한 혼화재료의 적용 또는 배합설계상 조정을 통한 강도의개선 등이 필요할 것으로 판단된다.