Mineralogical Studies of Coal Fly Ash for Soil Application in Agriculture

Coal fly ash procured from Guru Gobind Singh Super Thermal Power Plant, Ropar, Punjab, India, was analyzed for its mineralogical content and thermal stability by x-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and physicochemical properties. XRD studies showed that major crystalline phases observed were quartz (SiO₂) and aluminum silicon oxide (Al_4.52Si₁.₄₈) with macro- and microelement (N, P, K, Mg, Zn, S, and Fe). Fly ash showed thermal stability up to 500°C and reduction in weight was up to 200°C, primarily due to loss of water and decarboxylation as revealed by TGA plots. FTIR of fly ash showed that the most prominent peaks in the spectra corresponded to Si–O and Al–O stretch vibrations. Coarse-grain accumulation of fly ash indicated the presence of 70% of fine-grained particles of 0.075 mm. Coal fly ash was alkaline in nature (pH 7.85 ± 0.03) with an electrical conductivity of 0.14 ± 0.02 µS m^?1, water holding capacity of 62%, low bulk density of 0.99 g cm^?3, and a surface area of 0.96 m² g^?1. With properties similar to that of soil coal, fly ash represents a suitable material for use in specific quantities as a soil amending agent in agriculture.     

水热法合成NaP1型粉煤灰沸石的性能表征

通过碱性介质中的水热反应,由粉煤灰合成了单一沸石矿物种的NaP1沸石,并对合成产品进行了表征.经粉晶X射线衍射鉴定,合成产物中主要矿物成分为NaP1沸石,另有少量尚未反应的石英和莫来石.在电子显微镜下,粉煤灰颗粒呈球形且表面光滑,而合成产物颗粒表面粗糙.粉煤灰合成沸石含有大量的交换性Ca2 ,且与粉煤灰原料相比,SiO2含量明显减少,Al2O3稍有增加,SiO2/Al2O3比值由3.3降至1.8.红外光谱分析和差热分析证实了合成的粉煤灰沸石中沸石水的存在.NaP1型粉煤灰沸石的阳离子交换容量(CEC)达213 cmol/kg,比表面积达29 m2/g,分别比粉煤灰高约100倍和26倍.     

Performance Characteristics of Centrifugal Slurry Pump with Multi-Sized Particulate Bottom and Fly Ash Mixtures

The present study reports on the performance characteristics of the centrifugal slurry pump with multi-sized particulate slurry of bottom ash and fly ash mixtures. The performance characteristic of the pump was experimentally evaluated at rotational speed 1450 rpm for bottom ash slurries with and without the addition of fly ash in the concentration range of 10% to 50% (by weight). Addition of fly ash in the bottom ash was varied from 10% to 30% (by weight). The pump total head, overall efficiency, and pump input power at different flow rates were evaluated. The performance characteristics results show that the value of head and the efficiency of the pump depend on the solid concentration. It was also observed that the performance parameter of the pump strongly depends on slurry properties. The addition of fine particles fly ash in the coarser particles of bottom ash slurry, leads to reduce the additional head losses in the pump. The pump performance in terms of head and efficiency improved with addition of fly ash in bottom ash slurry.     

A Comparative Study on the Performance Characteristics of Centrifugal and Progressive Cavity Slurry Pumps with High Concentration Fly Ash Slurries

Slurry pumps are extensively used in the hydraulic transportation of fly ash slurries through pipes in thermal power plants. Today, a wide range of slurry pumps are available and the most commonly used pumps are broadly classified into two main categories, namely, positive displacement and centrifugal pumps. These two types of pumps differ considerably in construction as well as in operating principle compared to the conventional pumps. The aim of the present study is to compare the performance characteristics of these two different types of pumps operating with high concentration fly ash slurries. For each type, the performance characteristics have been experimentally evaluated at the rated speed with water as well as with fly ash slurries in the concentration range of 50 to 70% by weight. The pump total head, overall efficiency, and pump input power as a function of the flow rate have been measured. The results obtained from the centrifugal slurry pump performance show that at rated speed, the head and efficiency of the pump decrease with an increase in solid concentration and the effect is strongly dependent on slurry properties. The pump input power also increases monotonically with an increase in solid concentration. In the case of progressive cavity screw pump, pump performance characteristics and behavior were completely different compared to the centrifugal slurry pump. At rated speed, the head developed and the efficiency of the pump improved with an increase in solid concentration for progressive cavity screw pump.     

Synthesis, Characterization, and Formation Process of Na-X Zeolite from Coal Fly Ash

Using the SiO₂ and Al₂O₃ components of the amorphous phase in coal fly ash (Fa), Fa was converted to Na-X zeolites in NaOH-NaAlO₂ solutions by stirring at 35°C for 72 hr and then aging at 85°C for a given period. The molar ratio SiO₂/Al₂O₃ of the starting materials was controlled from 2.0 to 13.2. The resulting materials were characterized by various means. Increasing the SiO₂/Al₂O₃ ratio of the starting material increased the degree of crystallinity of faujasite, exhibiting a maximum at SiO₂/Al₂O₃ = 8.0. The faujasite formed was identified as Na-X zeolite with Si/Al = 1.20. The amorphous phase in Fa was dissolved during the stirring to form a precursor of zeolite, such as amorphous aluminosilicate. The Na-X zeolite was formed by aging for 24 hr, and the degree of crystallinity of this material was increased with the increasing aging period. The cation exchange capacity and specific surface area were increased with the increasing degree of crystallinity of the Na-X zeolites.     

Oil-Shale Fly Ash Utilization as Independent Binder of Natural Clayey Soils for Road and Airfield Base Construction

ABSTRACT

This article describes physicochemical interactions of different natural clayey soils with oil-shale fly ash (OSFA) from thermal power plants, dealing with the strengthening processes of new materials. Toward this end, a range of traditional and modern research methods were used, i.e., definition of the ultimate strength under uniaxial compression and rupture by the Brazilian method, temporary changes in moisture content and linear deformation, water and frost resistance, free CaO and SO₃, CaCO₃, XRD, and SEM. It was established that the surfaces of the initial component (OSFA and soils) particles were dissolved in porous alkaline solutions. The dissolution products gave rise to new amorphous and crystal formations. After 28 days, the strength of the samples reached 2–12 MPa but, after 90 days, it rose to 4–31 MPa. It was found that the strength at every stage of hardening can be increased significantly by changing the proportion of the initial mixture's composition. The materials displayed very high water and frost resistance, with coefficients equaling or exceeding the 1.0 level, except the OFSA and loess combination. The materials developed are applicable for the construction of roads, airfields, and dam bases and for various types of foundations without traditional binders, such as cement, and without heating.     

Oil-Shale Fly Ash Utilization as Independent Binder of Natural Clayey Soils for Road and Airfield Base Construction

This article describes physicochemical interactions of different natural clayey soils with oil-shale fly ash (OSFA) from thermal power plants, dealing with the strengthening processes of new materials. Toward this end, a range of traditional and modern research methods were used, i.e., definition of the ultimate strength under uniaxial compression and rupture by the Brazilian method, temporary changes in moisture content and linear deformation, water and frost resistance, free CaO and SO₃, CaCO₃, XRD, and SEM. It was established that the surfaces of the initial component (OSFA and soils) particles were dissolved in porous alkaline solutions. The dissolution products gave rise to new amorphous and crystal formations. After 28 days, the strength of the samples reached 2-12 MPa but, after 90 days, it rose to 4-31 MPa. It was found that the strength at every stage of hardening can be increased significantly by changing the proportion of the initial mixture's composition. The materials displayed very high water and frost resistance, with coefficients equaling or exceeding the 1.0 level, except the OFSA and loess combination. The materials developed are applicable for the construction of roads, airfields, and dam bases and for various types of foundations without traditional binders, such as cement, and without heating.     

酸法生产粉煤灰工艺中设备的腐蚀与材料选择

本文通过对酸法溶解粉煤灰工艺技术中的工艺流程描述,列举出了可产生腐蚀现象的相关部位及零件,并对使用的相应不锈钢材质进行腐蚀机理分析,根据其腐蚀现象归纳出腐蚀类型,探讨了不锈钢材料的优选原则与材料选择。     

Variation of physical and rheological properties of fly ash slurries with particle size and its effect on hydraulic transportation at high concentrations

In thermal power plants, fly ash is collected at the bottom of electrostatic precipitator (ESP) hoppers and transported to common sump for further disposal to the ash pond by slurry pipelines. The fly ash from different fields of ESP hoppers vary widely in particle size as well as quantity. Depending on the sequence of evacuation, the overall particle size distribution (PSD) would vary with time which in turn would affect the head requirement in the high concentration slurry disposal (HCSD) system. Fly ash samples from different fields of ESP hoppers of a thermal power plant have been analyzed for their physical properties namely the PSD, specific gravity, settling characteristics, pH of the slurry, etc. and for rheological properties in the concentration range of 60–70% (by weight). The particle size (d_wm) of the fly ash samples decreases with the increase in ESP field, whereas the static settled concentration and specific density increase. The pH values of all samples are almost constant and nonreactive in nature. The rheological properties namely yield stress and Bingham viscosity of the fly ash slurries from different fields of ESP hoppers increase with increase in concentration. Further at any given concentration, these parameters exhibit a strong dependence on particle size. Using these properties and treating the distribution of particles across the pipe cross section as homogeneous in the concentration range of 60–70% (by weight), CFD computations are made to evaluate the head requirement in a HCSD pipeline. The head loss increases with increase in concentration for all fields of ESP hoppers. The present study also shows that head requirement varies significantly by mixing different proportion of fly ash from different ESP fields.     

粉煤灰激活中ATR/FTIR、FTIR和NMR的分析与比较

采用ATR/FTIR对南京热电厂Ⅰ级粉煤灰及经过NaOH激发后的样品进行了分析，并且同FTIR和NMR的分析结果进行比较。研究结果表明：以表征表面特征的ATR/FTIR方法可以清晰地表征粉煤灰表面出现的变化，且随着碱浓度的提高变化明显，而以表征宏观几率特征的FTIR和NMR则没有反映出粉煤灰表面出现的变化。ATR/FTIR在粉煤灰的表面研究中具有独到效果。     

微生物絮凝剂与粉煤灰联合处理水中pb2+的响应面优化

目前,用微生物絮凝剂(MBF)与粉煤灰联合处理重金属的方法鲜有报道.从内蒙古地区盐碱地中筛选出一株具有较高絮凝活性的菌株HG6,16S rDNA鉴定为Oceanobacillus polygoni,以其制备出MBF.采用BBD(box-behnken design)法研究了MBF与粉煤灰联合去除废水中pb2+的最佳条件组合,设定响应值为pb2+的去除率,方差分析显示,模型F值为17.30,P=0.000 5,相关系数R2 =0.901 7,拟合模型极显著.在最优条件:粉煤灰投加量1.46 g/L,MBF投加量0.888 g/L,CaCl2投加量15.6 mL/L(1％,w/V)时,测得pb2+的去除率达到99.75％.通过傅里叶变换红外光谱、Zeta电位分析发现,MBF-HG6与粉煤灰对pb2+的捕集过程中存在电中和及吸附架桥作用机理.     

Characterization of Rice Hull Ash and Its Performance in Turbidity Removal From Water

This study characterizes the locally obtained samples of rice hull ash and investigates its performance on turbidity removal from water. Four samples of this material were studied, namely, unwashed parboiled rice hull ash (UPRHA), washed parboiled rice hull ash (WPRHA), unwashed unparboiled rice hull ash (UUPRHA), and washed unparboiled rice hull ash (WUPRHA). Scanning electron microscopy (SEM), x-ray diffractometer (XRD), and Fourier infrared spectroscopy (FTIR) were carried out to characterize these samples. A filtration process was carried out to investigate the effectiveness of the rice hull ash medium in removing water turbidity. The XRD results showed the silica, which is present in the ashes, to be cristobalite, quartz, and tridymite. The silica contents of the UUPRHA and WUPRHA were observed to be 77.10% and 98.24%, respectively, while those of UPRHA and WPRHA were 79.07% and 94.97%, respectively. The SEM images showed agglomeration of ash particles after the ashes were washed. The washed RHA samples showed improved pH, a good percentage of turbidity removal (<5 NTU) from water sample. Washing RHA with distilled water increased the efficiency of RHA in turbidity removal from water and regulated water pH to an acceptable range.     

矿用双抗塑料制品的应用研究进展

从抗静电和阻燃两方面总结了煤矿井下对塑料制品的要求,并综述了聚氯乙烯、聚乙烯、玻璃钢等塑料制品的抗静电性及阻燃性,指出抗静电剂和阻燃剂研发缓慢限制了我国工程塑料在煤矿井下的应用,新型高效抗静电剂和阻燃剂是塑料制品在煤矿井下应用的研究方向。     

粉煤灰活性硅铝的微波制样快速测定方法

讨论了粉煤灰活性硅铝测定中加热回流制样方法的不足和采用微波技术制样的原理与关键参数.试验研究了影响粉煤灰活性硅铝测定的微波制样功率和时间,与加热回流制样的测定结果比较表明,采用210W微波处理15min制样所测定的活性硅铝结果与加热回流方法制样所测得的相当.确定粉煤灰活性硅铝测定中微波制样条件为210W微波处理15min,微波制样可用于快速测定粉煤灰活性硅铝.     

汽车悬架控制臂液压衬套动态特性实测与计算分析

在汽车悬架系统中,为了满足其低频振动控制和高频隔振性能的要求,对控制臂衬套动态特性的要求是不一致的。常见的橡胶衬套很难提供在低频振动控制时所需要的大阻尼。液压衬套是一种可在一个较大的频率范围内提供大阻尼和大刚度的振动控制元件,目前它在悬架系统中得到了广泛的应用。介绍了可在径向或轴向方向提供大阻尼和大刚度的两种结构型式的液压衬套,实验测试了它们的静态特性、动刚度和阻尼及其与激振频率和激振振幅的相关性;建立了液压衬套动特性计算分析的集总参数模型,利用该模型计算分析了一液压衬套的动刚度和滞后角,计算结果和实验值的对比结果证明了模型的正确性。最后给出了液压衬套在解决由于路面或车轮不平衡激励而引起方向盘振动问题的应用实例。     

Radio Isotope Method for Rapid Determination of Proppant Concentration in Working Mixtures Used in Hydraulic Fracturing of Oil and Gas Containing Strata

A radio isotope method for rapid determination of proppant concentration and a test measurement unit RIKP-01 constructed on the basis of it provides a relative error in determining proppant concentration of not more than ± 3.5% with a measurement time of 15 sec that is four times better than for the world leader, i.e., the firm Halliburton (USA).Translated from Izmeritel’naya Tekhnika, No. 3, pp. 68–70, March, 2005.