粉煤灰改良饱和黄土动力特性研究

以资源循环再利用与提高饱和黄土地基抗震性能为目的,通过对不同掺量粉煤灰改良饱和黄土进行动弹性模量-阻尼比试验,研究了动荷载作用下粉煤灰掺量对饱和改良黄土动骨干曲线的影响,同时对不同掺量粉煤灰改良饱和黄土初始动弹性模量、最大动应力幅值、动弹性模量与阻尼比进行了对比研究。研究结果表明:饱和压实素土与不同掺量粉煤灰改良饱和黄土动骨干曲线均可用双曲线模型进行描述,模型参数受粉煤灰掺量影响较大;粉煤灰的掺入可有效改善饱和黄土地基抗震性能,随粉煤灰掺量增加,不同掺量饱和改良黄土动弹性模量与阻尼比分别总体呈增大与减小趋势;考虑粉煤灰改良饱和黄土抗震性能与经济成本,提出了饱和改良黄土最佳粉煤灰掺量为20%~25%;并基于回归分析,给出了饱和改良黄土动弹性模量衰减经验公式与阻尼比增长经验公式及其拟合参数。     

Demobilization of Heavy Metals from Mine Waters

The present study elucidates the remediation of mine waters by means of geochemical barriers („active barriers“). Active barrier systems (ABS) are developed, which can prevent heavy metal dispersion by introducing the barrier into the mine. Therefore, low‐cost materials are investigated which can remove contaminants by chemical, and/or physical mechanisms from water. The materials investigated are industrial by‐products (e.g. fly ash, red mud, scale arrears), natural wastes (e.g. tree bark), and relatively cheap natural products (bentonite, zeolites). Red mud and fly ash show the best results for the removal of Zn, Cd, Ni, and Mn from model water. Cd seems to have the strongest binding of the investigated metals on the sorption sites. The main mechanisms of metal removal from solution in this case are sorption and precipitation. Both materials have very good sorption and acid neutralization capacities (ANC), but ANC seems to be the determining factor.     

无机盐改性对沸石覆盖技术控制底泥氮磷释放的影响研究

通过试验,考察了无机盐改性对沸石覆盖控制底泥氮磷释放效果的影响,并对沸石覆盖技术控制底泥氮磷释放的机理进行初步探讨,结果表明:①NaCl及CaCl2改性对沸石吸附氨氮的性能影响不大;CaCl2改性可以提高沸石Ca2 的交换量而降低Na 的交换量,NaCl改性则可以明显降低Ca2 的交换量和增加Na 的交换量.②NaCl及CaCl2改性对沸石覆盖技术控制底泥氨氮的释放影响不大,而对控制底泥磷的释放则影响较大,沸石覆盖控制底泥磷释放效率从大到小依次为CaCl2改性沸石＞天然沸石＞NaCl改性沸石.③沸石覆盖技术控制底泥氨氮释放的机理为沸石的物理吸附和阳离子交换作用,控制底泥磷释放的机理包括沸石的机械阻挡作用和沸石与铵所交换出来的Ca2 对磷酸盐的固定作用.     

Experimental studies in the sorptive extraction of boron and lithium from thermal waters

We studied the extraction of boron and lithium from prepared and industrial solutions using industrial ionites ATsD-4-1p, AV-16 GS, AN-3, and AV-17-8 and by modified zeolites from the Yagodnoe field, Kamchatka. The modification was performed using aluminum hydroxide, hydrochloric hydroxylamine, or urotropin. We found that when modified with Al(OH)₃, zeolite shows selectivity with regard to lithium ions. When modified with hydrochloric hydroxylamine or with urotropin zeolites can be used for sorption of boric acid from naturally occurring and industrial solutions. The sorptive capacity of the modified zeolites is 30% higher on average compared with that of industrial ionites.     

动荷载作用下粉煤灰改性黄土的震陷特性

针对黄土地区实现工程施工材料本土化和科学利用粉煤灰问题,对不同配比条件下粉煤灰改性黄土进行重塑非饱和试件的动三轴震陷试验,研究其在动荷载作用下的震陷特性,分析粉煤灰掺入量对动变形模量和动残余应变的影响变化规律。研究结果表明:粉煤灰掺入量对黄土震陷性质的影响较大。相同固结应力水平下,动变形模量和动残余应变随粉煤灰掺入量呈现出不同的变化规律,随着粉煤灰掺入量的增加,黄土动变形模量也随之增大,残余应变则减小。动变形模量与动残余应变之间的变化趋势满足幂函数关系;黄土掺加约20%粉煤灰改性后就能够有良好的抗震陷性能。研究成果可为黄土地区地基的抗震防震设计提供借鉴依据,具有重要的工程实用价值。     

粉煤灰改良饱和黄土的抗液化特性

为了经济、环保地达到改良处理减轻饱和黄土地基液化震害的目的,通过配备不同粉煤灰掺量的改良黄土进行动三轴试验,研究饱和粉煤灰改良黄土的动应力、动应变和动孔隙水压力变化特征,分析粉煤灰掺量对饱和改良黄土液化应力比、动残余变形和动孔隙水压力的影响规律,并结合微结构试验结果,探讨饱和粉煤灰改良黄土抗液化的物理化学机制。结果表明:粉煤灰掺量对饱和改良黄土的液化应力比、动应变和动孔隙水压力比均具有较为显著的影响。随着粉煤灰掺量的增加,饱和改良黄土的液化应力比持续增加,且当掺量达到15%后,继续增加粉煤灰掺量时改良黄土的液化应力比增加显著。饱和改良黄土的动应变和动孔隙水压力比均随着粉煤灰掺量的增加而减小;掺量达到25%后,饱和改良黄土不液化。饱和粉煤灰改良黄土的SEM细观结构试验照片中呈现大量的圆球状、粒状粉煤灰颗粒和絮凝状胶结物,表明其抗液化的物理化学机制主要包括粉煤灰的水化作用、胶体生成物和颗粒的填隙作用和粉煤灰对游离水的吸附作用。     

Nutrients adsorption from seawater by new porous carrier made from zeolitized fly ash and slag

This study investigated the adsorption and precipitation of phosphate by blast furnace slag (BFS) separately.

In order to evaluate the adsorption capacity of BFS, BFS was treated before its use by acid. The authors aim to develop a new porous carrier to adsorb simultaneously ammonium and phosphate from seawater under eutrophic conditions. The current paper deals with a promising new approach to improve the utilization of some industrial solid wastes such as BFS and zeolite synthesized from fly ash [ZFA(Fe)] by their solidification to cylindrical porous carriers using a hydrothermal hot-pressing (HHP) method.

Attempts to produce porous carriers using an arranged HHP method with different porosities (24%, 40% and 52% (v/v)) were carried out. Physical properties of carriers such as porosity, compressive strength and height have been investigated. Laboratory studies showed strong evidence that the porous carrier was very selective towards phosphate and ammonium. The results demonstrated the role of porosity in enhancing phosphate and ammonium adsorption by the increase of the surface area per weight. The estimates of the parameters and the correlation coefficients according to the Freundlich equations revealed that adsorption was related to the porosity of carriers and phosphate and ammonium were adsorbed well on the carriers having large porosity.

The results suggested that developing carrier with high porosity was a promising way to enhance nutrients adsorption.     

Nutrient Recovery from Human Urine Using Pretreated Zeolite and Struvite Precipitation in Combination with Freezing‐Thawing and Plant Availability Tests on Common Wheat

The nutrient rich fractions in wastewater originating from human urine and can be recovered as solids for more efficient recycling, facilitated handling and storage for reuse in agriculture. Freezing and thawing can be used to concentrate the urine nutrients. Phosphorus (P) and nitrogen (N) can be precipitated as struvite [(Mg,Ca)(K,NH₄)(PO₄)·6H₂O] by adding MgO and additional nitrogen can be recovered by using zeolites. The zeolite in this study was pretreated in two ways: (i) washed and (ii) washed and thermally treated. The P recovery was high (> 97%) and the N recovery was ca. 50 to 60%. There was no significant difference in the nitrogen recovery among the different pretreated zeolites or between the pretreated and the untreated zeolite. Freezing had a positive effect on the nutrient concentration. The acute toxicity of the supernatants was tested on Daphnia magna to evaluate the possibilities of discharging the remaining supernatants to a recipient. The supernatants from the frozen treatments and from the unfrozen and washed zeolites were much less toxic than those of the original urine. The minerals acted as slow‐release fertilizers in climate chamber tests on spring wheat.     

土工格栅加筋粉煤灰改良黄土力学特性研究

随着西部黄土地区城镇化进程的加快,填挖结合的新增用地方式要求地基处理技术需要重点解决填方区的强度与变形问题。论文将粉煤灰作为改性填料对黄土进行改良,通过直剪试验、三轴试验、湿陷试验与扫描电镜试验,分析不同粉煤灰掺入比条件下加筋与未加筋黄土试样的强度变化规律、宏观破坏特征和微结构特征。结果表明:采用粉煤灰改良和土工格栅加筋后,黄土的最优含水率增大,最大干密度降低。当粉煤灰掺入比λ=20%时,加筋改良效果最好,黄土的峰值强度、残余强度和等效内摩擦角均有大幅提高,侧向变形显著减小,且能有效降低其湿陷性。微结构分析表明:粉煤灰对黄土的改良主要体现在颗粒直接填充和化学结晶体交织成的网状填充两种类型的强化作用,改良后黄土的孔隙率与孔隙尺寸均有所下降。研究结果可为黄土地区填方边坡与填方路基的改良加固提供参考。     

Laboratory Simulation of Fly Ash as an Amendment to Pyrite-Rich Tailings

Column leaching experiments show that fly ash Interlayered with sulfide-rich tailings can reduce the vertical permeability of tailings by at least three orders of magnitude. Chemical reactions between the fluid, alkaline fly ash from Western coal and pyritic tailings result in a one to three order of magnitude reduction in the dissolved metals content of the effluent solution. Metal precipitation, which produces the dissolved metals reduction, is a significant element in the permeability reduction. The combined factors reduce the metals flux from the tailings by four to six orders of magnitude. We believe that tailings ponds with fly ash layers as amendments can greatiy reduce ground water contamination from pyritic tailings. In addition, concentrated application of fly ash layers near the end of mining should act to restrict infiltration and access of oxygen, thereby enhancing reclamation. Similar results maybe obtainable using other amendments with lower base capacity (lime, crushed limestone, trona).     

加高扩容贮灰场地震响应特性及其稳定性评价

贮灰场主要用于储存燃煤电厂排出的粉煤灰和炉渣,在加高扩容时应特别注意地震作用下的稳定性。通过现场试验和数值模拟手段,研究了某贮灰场加高扩容前后的液化可能性、动力响应及稳定性。结果表明:(a)加高扩容后四级坝的峰值加速度和峰值水平位移相比现状三级坝响应更加显著。(b)子坝坝体粉煤灰不液化,库内可能出现液化。输入地震动峰值加速度越高,库内液化区明显增大,加高扩容后库内液化区域增大。(c)地震作用下贮灰场三级坝与拟筑四级坝的潜在滑动面位置均位于子坝坝系。随拟筑四级坝高程增加,最小安全系数减小。根据该贮灰场Ⅷ度抗震设防烈度要求,加高扩容前后贮灰场的稳定性均满足抗震规范要求。研究成果可为贮灰场加高扩容后的抗震设计提供理论依据。     

Liquefaction strength of fly ash reinforced with randomly distributed fibers

In this paper a study on the improvement of liquefaction strength of fly ash by reinforcing with randomly distributed geosynthetic fiber/mesh elements is reported. A series of stress controlled cyclic triaxial tests were carried out on fly ash samples reinforced with randomly distributed fiber and mesh elements. The liquefaction resistance of reinforced fly ash is defined in-terms of pore pressure ratio. The effects of parameters such as fiber content, fiber aspect ratio, confining pressure, cyclic stress ratio, on liquefaction resistance of fly ash have been studied. Test results indicate that the addition of fiber/mesh elements increases the liquefaction strength of fly ash significantly and arrests the initiation of liquefaction even in samples of loose initial condition and consolidated with the low confining pressure.     

Self-Organizing Maps for identification of zeolitic diagenesis patterns in closed hydrologic systems on the Earth and its implications for Mars

We have conducted a survey of zeolite occurrences in saline-alkaline paleolake deposits on Earth to identify the most prominent zeolite alteration patterns and to characterize the most common authigenic minerals and their paragenetic relationships. We collected the bulk mineral assemblages (from previous and our studies) as identified by X-ray diffraction from zeolitic tuff beds and associated sedimentary beds from thirteen paleolake deposits from the USA, Mexico, Greece, and Tanzania. We applied the Kohonen Self-Organizing Maps (SOM) to look for interesting patterns in the tuff bed mineral assemblages without prescribing any specific interpretation, and for information reduction and classification. Decision Tree (DT) method was applied to characterize these clusters. We were able to define clear class boundaries between fresh glass, non-analcime zeolites, analcime, and K feldspar. The non-analcime zeolites were further grouped into several classes based on mineral type. We also discuss the potential implications for Mars, showing that the mineral assemblages of diagenetic facies identified by SOM and DT can be used to test or validate the orbital, in situ, or modeling results, while the trained SOM provides a robust generalized ability to classify the new mineral assemblage data into the most common diagenetic facies identified in saline-alkaline paleoenvironments that contain zeolites. The study concludes that generalizing the complex geochemical behaviors using unsupervised statistical learning methods can help to identify the most prominent geochemical behaviors.     

土壤剖面中粉煤灰垂向迁移的磁响应

对浙江省安吉县梅溪发电厂粉煤灰贮灰场附近的土壤短剖面进行环境磁学、元素含量及粒度研究.借助模糊聚类分析,分辨出粉煤灰原位堆积、富集、迁移深度及未受污染土壤特征.剖面上部0～14cm为粉煤灰的原位反映,多畴磁铁矿主导了该段样品磁性.其中11～14cm处磁性矿物和金属元素有所富集.14～21cm为粉煤灰在土壤中的迁移深度.迁移段土壤中亚铁磁性矿物及Pb、Zn等金属含量介于底部未污染土壤与上部粉煤灰原位堆积层之间.单畴斜交反铁磁性矿物及来源于上部粉煤灰的多畴磁铁矿共同主导了该段土壤的磁性特征.21cm以下土壤基本未受粉煤灰污染,单畴斜交反铁磁性矿物是其主要磁性矿物.指标聚类分析表明,亚铁磁性矿物主要赋存在粗粉砂中,单畴磁晶粒主要存在于细粉砂中.χ、ARM、SIRM与Cu、Mn、Pb、Zn呈显著相关.结合多元统计分析,磁参数可用于追踪、识别粉煤灰在土壤剖面中的垂向迁移.     

Ionenselektiver Austausch an slowakischem Klinoptilolith-Tuffit

Clinoptilolite, a natural zeolite is efficient for removing ammonia from water. The use of natural zeolites deposited at Ni?ný Hrabovec, ?SSR, for ammonia removal from model solutions is studied under various conditions: pH, temperature, hydrodynamic regime, zeolite-modification. The optimal ion exchange conditions, the equilibrium and capacity data in real waste water of ?SSR-clinoptilolite tuff were investigated.     

Evaluation of Amendments to Control Phosphorus Losses in Runoff from Pig Slurry Applications to Land

If spread in excess of crop requirements, incidental phosphorus (P) losses from agriculture can lead to eutrophication of receiving waters. The use of amendments in targeted areas may help reduce the possibility of surface runoff of nutrients. The aim of this study was to identify amendments which may be effective in reducing incidental dissolved reactive phosphorus (DRP) losses in surface runoff from land applied pig slurry. For this purpose, the DRP losses under simulated conditions across the surface of intact grassland soil cores, loaded with unamended and amended slurry at a rate equivalent to 19 kg P ha^?1, were determined over a 30 h period. The effectiveness of the amendments at reducing DRP in overlying water were (in decreasing order): alum (86%), flue gas desulfurization by‐product (FGD) (74%), poly‐aluminum (Al) chloride (PAC) (73%), ferric chloride (71%), fly ash (58%), and lime (54%). FGD was the most costly of all the treatments (€7.64/m³ for 74% removal). Ranked in terms of feasibility, which takes into account effectiveness, cost, and other potential impediments to use, they were: alum, ferric chloride, PAC, fly ash, lime, and FGD.     

Magnetic mineralogy and grain-size dependence of hysteresis parameters of single spherules from industrial waste products

The use of magnetic susceptibility as a proxy for the relative degree of industrial pollution of soils and sediments is only qualitative and complications arise when unmixing the contributions from different sources. Detailed characterization of anthropogenic magnetic phases is needed in order to discriminate the input from different sources. The present study investigates magnetic fractions from fly ashes from different thermoelectric power plants and lagooned ash from metal works in Bulgaria, to further our knowledge of potential sources. Thermomagnetic analysis of saturation magnetization (M_s) and magnetic susceptibility (K) revealed a low-substituted magnetite-like phase in power-plant fly ashes and magnetite/maghemite phases in lagooned ash. Magnetic hysteresis measurements on single spherules from the wastes are combined with subsequent SEM/EDX examination of the same grains, allowing for the grain size dependence of the hysteresis parameters to be directly obtained for the studied anthropogenic phases. The results suggest that the structure-sensitive magnetic parameters for the lagooned ash show stronger size dependence compared to the published data for synthetic crushed magnetites, which is due to the complex internal structure and stress level in the anthropogenic phases formed under fast cooling conditions. Moreover, the Day plot for the studied single grains shows the presence of different correlation lines for fly ashes and the lagooned ash, i.e. it discriminates between the sources.     

贮灰场子坝粉煤灰动力特性试验研究

贮灰场子坝冲填粉煤灰的动力特性是评估挡灰坝在地震作用下动力稳定性的关键因素。为探究冲填粉煤灰的动力变形和强度特性,利用液压控制振动三轴试验仪测试饱和沉积灰和冲填灰两类试样在偏压固结条件下的动应力-动应变关系、动强度、阻尼比和动孔隙水压力。结果表明:试样骨干曲线均表现出应变硬化特征,可近似描述为双曲线型关系。此外,循环振次增大导致试样动强度降低,且主要与动黏聚力降低有关,受内摩擦角影响较小。双对数坐标轴下,无量纲处理后的阻尼比与动剪切模量近似呈线性关系,且与围压关系不显著。不同围压下动孔压水平随破坏振次增大仅在较窄范围内变化,为简便计算,可忽略围压和循环振次对动孔压水平的影响。据此,可采用Finn公式描述偏压固结下粉煤灰试样的动孔隙水压力特征。     

喀斯特地区梯级水库建造对水化学分布的影响

为深入了解河流梯级筑坝对喀斯特地区河流水化学分布的影响,于2017年1、4、7和10月别对乌江干流洪家渡水库(多年调节)、乌江渡水库(季调节)和索风营水库(日调节) 3个具有不同滞留时间的水库进行水样采集,分析入库水、坝前剖面水和下泄水的水化学特征,探讨河流梯级筑坝对水化学分布及风化速率估算的影响.研究结果表明:3个水库深层水比表层水HCO3-浓度分别高12.9%、5.5%和8.0%,Ca~(2+)浓度分别高15.9%、2.4%和8.5%.河流梯级筑坝一定程度上改变了水体水化学组成,从而影响碳酸盐岩风化速率估算.整体上,洪家渡水库、索风营水库和乌江渡水库的全年风化速率变化范围分别为:-1.7%～15.4%、-5.6%～1.1%和-0.3%～3.4%.河流筑坝作用对风化速率估算及主量离子浓度的影响:HCO_3~-与Ca~(2+)浓度分布均为:洪家水库乌江渡水库索风营水库,这与水体滞留时间长短规律一致,表明水体滞留时间影响着水化学的组成分布.同时水体离子浓度表现出明显的季节性差异,丰水期各水库变化率明显大于枯水期.上述结论表明喀斯特地区河流连续筑坝后水化学组成及分布特征发生了一定程度改变,影响流域化学风化速率的估算,且影响程度随水体滞留时间延长而增大,并受气温影响.因此,今后在估算流域风化速率及探究水化学空间变化时应对筑坝作用加以考虑,以便更加准确地评估喀斯特流域岩石风化在全球碳循环中的作用.     

Verfahren zur katalytisch-oxydativen Entsulfidierung von Abwässern

The oxidative conversion of strongly alkaline sulphide concentrations in wastewaters from the wet molybdenite enrichment is successfully performed within a relatively short time by the application of atmospheric oxygen, “Winkler adsorbent” (activated form of ash from Winkler generators) or “Winkler generator ash” and chlorinated lime at the same time. The reaction times were 60… 90 min at residual sulphide concentrations of 1… 10 mg/l. The initial concentrations of sulphide were between 400 and 1,200 mg/l. It was proved by comparative investigations that the “Winkler absorbent” or the “Winkler generator ash” have a catalytical effect during the oxidation by air. Therefore, also, e.g., at an initial concentration of sulphide of 600 mg/l only 4 g/l chlorinated lime were required, which corresponded to only about 0.13 times the stoichiometrically calculated quantity with the available chlorine content being taken into account. Flotation cells are suitable as reactors.