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Efficient stabilization of dredged sludge with high water content using an improved bio-carbonation of reactive magnesia cement method

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3760-3771页

作者： Rui Wang Chaosheng Tang Xiaohua Pan Dianlong Wang Zhihao Dong Xiying Zhang xiancai lu School of Earth Sciences and Engineering Nanjing UniversityNanjing210023China Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lake Qinghai Institute of Salt LakesChinese Academy of SciencesXining810008China

This study proposed an improved bio-carbonation of reactive magnesia cement(RMC)method for dredged sludge stabilization using the urea pre-hydrolysis *** on unconfined compression strength(UCS),pickling-drainage,and scanning electron microscopy(SEM)tests,the effects of prehydrolysis duration(T),urease activity(UA)and curing age(CA)on the mechanical properties and microstructural characteristics of bio-carbonized samples were systematically investigated and *** results demonstrated that the proposed method could significantly enhance urea hydrolysis and RMC bio-carbonation to achieve efficient stabilization of dredged sludge with 80%high water content.A significant strength increment of up to about 1063.36 kPa was obtained for the bio-carbonized samples after just 7 d of curing,which was 2.64 times higher than that of the 28-day cured ordinary Portland cement-reinforced *** elevated T and UA could notably increase urea utilization ratio and carbonate ion yield,but the resulting surge in supersaturation also affected the precipitation patterns of hydrated magnesia carbonates(HMCs),which weakened the cementation effect of HMCs on soil particles and further inhibited strength enhancement of bio-carbonized *** optimum formula was determined to be the case of T?24 h and UA?10 U/mL for dredged sludge stabilization.A 7-day CA was enough for bio-carbonized samples to obtain stable strength,albeit slightly affected by *** benefits of high efficiency and water stability presented the potential of this method in achieving dredged sludge stabilization and resource *** investigation provides informative ideas and valuable insights on implementing advanced bio-geotechnical techniques to achieve efficient stabilization of soft soil,such as dredged sludge.

关键词： Reactive magnesia cement(RMC)biocarbonation Urea pre-hydrolysis Dredged sludge Efficient stabilization Unconfined compressive strength Microbially induced carbonate precipitation(MICP)

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Thermodynamic properties of calcium ferrite-type MgAl_2O_4:A first principles study

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Science China Earth Sciences 2016年第4期59卷 831-839页

作者： YIN Kun ZHOU HuiQun lu xiancai State Key Lab for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing University

The diamond anvil cell experiments have revealed that the calcium ferrite(CF)-type aluminous phase is probably an important component of subducted mid-oceanic ridge basalt(MORB) in the lower mantle. In this study, we have performed first principles lattice dynamics calculations for the Mg Al_2O_4 end-member of the aluminous phase based on density functional perturbation theory using two functionals within the local density approximation(LDA) and generalized gradient approximation(GGA) for bracketing the calculated properties at their lower and upper limits, respectively. A simple empirical pressure correction at zero temperature has been applied to both LDA and GGA. The results of room-temperature equation of state(EOS) and zero-pressure thermal expansion calculated by GGA with pressure correction have shown the best agreement with available experimental data. The high-pressure and temperature thermodynamic properties have been obtained using the GGA with correction method. The pressure-volume relations are fitted with a third-order high-temperature Birch-Murnaghan EOS. The isobaric heat capacity, the coefficient of thermal expansion and isothermal bulk modulus are fitted with polynomials and their coefficients are reported in the range of 0–40 GPa and 300–2000 K. The density profile of MORB estimated using the computational thermo-elastic constants supports the hypothesis that the subducted oceanic slabs could gain enough downwelling forces into the lower mantle.

关键词： CaFe2O4-type MgAl2O4 Density functional perturbation theory Thermodynamic properties First principles

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A molecular dynamics study of uranyl-carbonate complexes adsorbed on basal surfaces of clay minerals

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Chinese Journal Of Geochemistry 2015年第2期34卷 143-155页

作者： Lei Li Xiandong Liu xiancai lu State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing University

We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species(UO_2^(2+)) to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and *** ion can form various complexes with carbonates,namely,[UO_2(H_2O)_5]^(2+),[UO_2(H_2O)3(CO_3)],[UO_2(H_2O)2(CO_3)_2]^(2-),[UO_2(CO_3)_3]^(4-).The simulations show that at aqueous clay interfaces,both uranyl species and surface type control the adsorption *** noncarbonato and monocarbonato uranyl species can form outer-sphere complexes on siloxane surfaces through electrostatic interaction,but the dicarbonato and tricarbonato uranyl complexes rarely adsorb on the siloxane *** outer-sphere adsorptions of the uranylcarbonate complexes on gibbsite surfaces are observed,which are fixed by hydrogen bonds between the ligands(carbonate and/or H_2O) and surface *** sorption behaviors derived in this study provide new insights into understanding the migration and enrichment of uranium and other radionuclides.

关键词：分子动力学模拟表面羟基吸附机制双氧铀碳酸酯黏土矿物铀酰络合物基底

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Anorthite dissolution promoted by bacterial adhesion:Direct evidence from dialytic experiment

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Science China Earth Sciences 2011年第2期54卷 204-211页

作者： ZHOU YueFei WANG RuCheng lu xiancai State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing University Nanjing 210093 China School of Resources and En virommentatl Engineering Hefei Univetwity of Teehnology Hefei 230009 China

Bacterial adhesion is crucial to the dissolution of minerals and rocks. By employing dialysis method, we designed comparative experiments to investigate the dissolution behavior of anorthite with the mediation of both adhered and non-adhered Paenibacillus polymyxa. The results show that during 10 experimental days, the dissolution of anorthite was promoted considerably by P. polymyxa and metabolites. Nanoscale precipitates were formed in contact experiment. Anorthite has a higher release of Ca and lower releases of Al and Si in dialysis experiment than in contact experiment. The difference implies that the release of Ca is controlled by mechanism of proton-exchange, whereas those of A1 and Si are controlled by ligand-complexation in which A1-O-Si bonds are destroyed first. Kinetically the release of Ca is controlled mainly by surface reaction and leached-layer diffusion. Both of them are restrained by adhered bacteria. The releases of AI and Si are controlled mainly by surface reaction, which is accelerated by adhered bacteria.

关键词： anorthite Paenibacillus polymyxa adhesion dissolution dialysis

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Molecular simulation study on K^＋-Cl^- ion pair in geological fluids

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Acta Geochimica 2017年第1期36卷 1-8页

作者： Mengjia He Xiandong Liu xiancai lu Rucheng Wang State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing UniversityNanjing 210046 People's Republic of China

This paper reports a classical molecular dynamics study of the potential of mean forces(PMFs),association constants,microstructures K^+-Cl^- ion pair in supercritical *** constrained MD method is used to derive the PMFs of K^+-Cl^- ion pair from 673 to 1273 K in low-density water(0.10-0.60 g/cm).The PMF results show that the contact ion-pair(CIP) state is the one most energetically favored for a K^+-Cl^- ion *** association constants of the K^+-Cl^- ion pair are calculated from the PMFs,indicating that the K^+-Cl^- ion pair is thermodynamically *** gets more stable as T increases or water density *** microstructures of the K^+-Cl^- ion pair in the CIP and solvent-shared ion-pair states are characterized in ***,we explore the structures and stabilities of the KCl-Au(I)/Cu(I) complexes by using quantum mechanical *** results reveal that these complexes can remain stable for T up to1273 K,which indicates that KCl may act as a ligand complexing ore-forming metals in hydrothermal fluids.

关键词： Molecular dynamics KCl Potential of mean force Association constant Geometry optimization

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A molecular simulation study of Cs-Cl and Cs-F ion pairs in hydrothermal fluids

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Acta Geochimica 2022年第3期41卷 325-334页

作者： Xi Zhang Xiandong Liu Tianhua Wang xiancai lu Rucheng Wang State Key Laboratory for Mineral Deposits Research School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023JiangsuChina

Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties of Cs-Cl and Cs-F ion pairs in hydrothermal fluids. The association constants(log_(10)K_(A)(m)) under a wide range of temperature(i.e. 298–1273 K) and fluid density(i.e. 0.1–1.0 g/cm^(3)) were derived from the potential of mean force(PMF) curves. The results indicate that CsCl and Cs-F ion pairs have similar stabilities. This is different from other alkali metal cations(e.g., Li^(+), Na^(+), and K^(+)), which prefer binding with F over Cl. The stabilities of Cs-Cl and Cs-F ion pairs increase with increasing temperature(except for the fluid density ≤ 0.1 g/cm^(3)) or decreasing fluid density, which is similar to other alkali halide ion pairs. Comparisons among the stabilities of CsCl/F and other alkali halide ion pairs indicate that the Li–F ion pair has the highest stability in hydrothermal fluids.

关键词： Cesium Hydrothermal fluids Association constant Hydration structure Molecular dynamics

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Oxidation and Mineralization of Mn^2＋ Ions Mediated by Pseudomonasputida： Insights from an Experimental Study

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Acta Geologica Sinica(English Edition) 2017年第4期91卷 1276-1285页

作者： CHEN Xiaoy lu xiancai LIU Huan LI Juan XIANG Wanli ZHANG Rui lu Jianjun MOE Key Laboratory of Surficial Geochemistry School of Earth Sciences and Engineering Nanjing University Nanjing Jiangsu 210093 China

The formation of manganese oxides in nature is commonly mediated by microorganisms. In this study, the mineralization of biogenic manganese oxidation mediated by Pseudomanas putida has been experimentally investigated by employing various characterization techniques, including SEM, FESEM, TEM, XRD, and STXM-NEXAFS. The results indicate that Mn^2＋ ions can be oxidized into Mn （IV） minerals （birnessite and pyrolusite） and Mn（III） minerals （hausmannite and feitknechtite）, successively. The primary products （birnessite and pyrolusite） further transformed into hausmannite and feitknechtite under Mn^2＋ ion-enriched conditions. However, birnessite and pyrolusite are the end- products of the continuous microbial oxidation processes. These biogenic Mn oxides are poorly crystallized, which provides them with a high potential for usage in environmental restoration of contaminated soils and waters contaminated with heavy metals. The approaches employed in this study will also enrich genesis research of biological oxidation of Mn（II） species in nature.

关键词： Pseudomanasputida Mn^2+ microbial oxidation biomineralization

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东南沿海火山岩地区火山黏土型锂矿的发现

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高校地质学报 2024年第4期30卷 409-417页

作者：邵小阳邓飞张忠进王汝成陆现彩车旭东广东省佛山地质局佛山528000 同济大学土木工程学院上海200092 内生金属矿床成矿机制研究国家重点实验室南京大学地球科学与工程学院南京210023 关键地球物质循环教育部前沿科学中心南京大学南京210023

广东省东北部石人背盆地上白垩统叶塘组中存在锂元素超常富集现象(Li_(2)O含量可达0.2%以上),具有寻找黏土型锂矿的良好前景。石人背盆地综合剖面测量、全岩地球化学分析及岩相学观察表明,锂的富集层位位于叶塘组中—上部页岩、泥岩和... 详细信息

广东省东北部石人背盆地上白垩统叶塘组中存在锂元素超常富集现象(Li_(2)O含量可达0.2%以上),具有寻找黏土型锂矿的良好前景。石人背盆地综合剖面测量、全岩地球化学分析及岩相学观察表明,锂的富集层位位于叶塘组中—上部页岩、泥岩和粉砂岩中,黏土矿物是锂的主要载体矿物,其成因与火山活动密切相关,初步判断为火山活动相关的黏土型锂矿。盆地构造为锂矿形成提供了有利的沉积环境,富锂沉积层的厚度可观,连续富矿的层位厚度可达226 m,找矿潜力较大。该矿的发现为中国东南沿海火山岩地区寻找超大型火山岩相关沉积型锂矿提供了重要的找矿线索。

关键词：火山黏土型锂矿叶塘组石人背盆地粤东北地区

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Highly Zn,Mn-rich calcite in calcareous tufa from the Qixiashan Pb-Zn Mine,Nanjing:a possible candidate for Zn-Mn removal from mining impacted waters

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Chinese Science Bulletin 2009年第8期54卷 1376-1383页

作者： LIU Ting WANG RuCheng lu xiancai LI Juan HU Huan School of Earth Sciences and Engineering State Key Laboratory for Mineral Deposits Research Nanjing University Nanjing 210093China

The exploitation of metallic mines may cause serious environmental *** removal of the heavy metals from the contaminated mining environments has become an urgent *** this paper,the occurrence and distribution of heavy metals in the calcareous tufa collected from the mining laneway of the Qixiashan Pb-Zn Mine in Nanjing were investigated by using multiple mineralogical *** by X-ray diffraction spectrum(XRD) shows that calcite is the major compo-nent of the calcareous *** heavy metals such as Mn,Zn,Mg,Fe and Pb are detected in calcite by means of electron microprobe *** the heavy metal contents in the hostrock and the formation water are significantly low,the contents of Mn,Zn,Mg,Fe and Pb in the tufa calcite are as high as 23.65 wt%,9.6 wt%,0.76 wt%,4.44 wt% and 0.66 wt%,*** back-scattered electron image shows complex compositional zoning texture in the tufa,which is linked directly to varia-tions in heavy metals,particularly in Mn and *** addition,we also observed floccule and helical precipitations,which may be derived from the metabolism of the *** is deduced that the occurrence and high concentration of heavy metals in tufa may be controlled by the activities of *** results presented in this work suggest that calcite will be an important candidate for the remediation of the heavy metal contamination in mining areas.

关键词：采矿影响方解石铅锌矿栖霞山候选人土法高锌南京

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Cataclastic rheology of carbonate rocks

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Science China Earth Sciences 2005年第8期48卷 1227-1233页

作者： lu xiancai SUN Yan SHU Liangshu GU Lianxing GUO Jichun ZHU Wenbin State Key Laboratory of Mineral Deposits Research Department of Earth SciencesNanjing UniversityNanjing 210093China

Based on the knowledge of the shallow-level mylonitization of detrital rocks and intrusive rocks,the poorly-known cataclastic rheology of carbonate rocks is discussed compre-hensively in this *** cases taken from eastern China are analyzed in various aspects including ductile-brittle fault zone,rock texture and structure,clastomylonite layer,leucocratic stress minerals,and frictional *** is proposed that the cataclastic flow structure represented by clastomylonite texture is a cooling pattern of flow assemblage charac-terized by cooling metamorphism,cooling mylonite and cooling stress *** a pattern is formed generally in mildly reducing physicochemical environments,and is commonly related to regional tectonism and mesothermal and epithermal mineralization.

关键词： carbonate rock cataclastic rheology clastomylonite ductile-brittle fault zone.

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