From in-situ coal to fly ash: a study of coal mines and power plants from Indiana

This paper presents data on the properties of coal and fly ash from two coal mines and two power plants that burn single-source coal from two mines in Indiana. One mine is in the low-sulfur (<1%) Danville Coal Member of the Dugger Formation (Pennsylvanian) and the other mines the high-sulfur (>5%) Springfield Coal Member of the Petersburg Formation (Pennsylvanian). Both seams have comparable ash contents (11%). Coals sampled at the mines (both raw and washed fractions) were analyzed for proximate/ultimate/sulfur forms/heating value, major oxides, trace elements and petrographic composition. The properties of fly ash from these coals reflect the properties of the feed coal, as well as local combustion and post-combustion conditions. Sulfur and spinel content, and As, Pb and Zn concentrations of the fly ash are the parameters that most closely reflect the properties of the source coal.     

Characterization of fly ash from a power plant and surroundings by micro-Raman spectroscopy

Fly ash samples were collected from a Portuguese power plant that burns low-sulphur coals from South Africa, U.S.A., Colombia, and Australia. The fly ashes were collected from the hoppers of the economizers, air heaters, electrostatic precipitators, and from the stack. The power plant air monitoring system was also sampled. The fly ash characterization was conducted by micro-Raman spectroscopy (MRS). The micro-Raman spectroscopic analysis permitted an efficient identification and characterization of different inorganic and organic materials present in fly ash: quartz, hematite, magnetite, calcite, glass, aluminium and calcium oxides, and different types of organic constituents.The study of the structural evolution of the unburned carbon/char material during their path through the power plant, though the use of Raman spectra and Raman parameters reveal that despite the high temperatures they reached, these materials are still structurally disordered. However, a structural evolution occurs in the char from the economizer up to the electrostatic precipitators where the char is structurally more disordered.The different features of the Raman spectra observed for carbon particles collected from the stack, together with the high range of variation of the Raman parameters, confirm the existence of different carbon particles in the stack, i.e., char and others (probably soot).The filters from the surroundings contain a variety of carbon particles with Raman parameters different from the ones obtained in the fly ash hoppers and stack. These are diesel particles as indicated by the values of W_D1, FWHM_D1, FWHM_G, W_G and ID1/IG obtained.     

Metal recovery from power plant ash: An ecological approach to coal utilization

The growing use of coal in electrical generation is resulting in power plant solid waste becoming a serious national problem. For 1977, approximately 62 million tonnes of utility ash was produced in the US. If oil and gas burning units that were originally designed to burn coal switch back to that fuel, utility ash will be the fourth largest solid material produced in the US. Disposing of such quantities of wastes poses siting and pollution problems which are becoming critical in areas experiencing increased land use competition.An alternative to disposal is to recover the constituent metals of the ash. Aluminium, iron, manganese, calcium, titanium, and magnesium are all present in fly ash, the utility waste that poses the major disposal problem. This paper indicates that metal recovery is an attractive alternative if national instead of special interest goals are maximized. Metal recovery from fly ash is attractive on environmental, self-sufficiency, and stragegic grounds although it may not be a wise decision for an individual entrepreneur. The geography of power plant location within the US is increasing the economical attractiveness of this potential resource since large, new facilities produce sufficient quantities of material that can be used in nearby metal smelters.     

富拉尔基热电总厂粉煤灰敏感性指标的试验研究

以富拉尔基热电总厂粉煤灰为研究对象，对其与水和温度有关的各项敏感性指标－渗透稳定性、软化特性、冻融强度损失和冻胀性进行了试验研究。     

Effect of some additives on synthesis of zeolite from coal fly ash

Hydrothermal conversion of fly ash into zeolites was conducted and the effects of the addition of sodium halide and waste solutions produced after zeolitization of fly ash, as well as the adjustment of the Si/Al ratio prior to synthesis process on the formation and cation exchange capacity (CEC) of zeolite product were evaluated. Both the addition of NaCl and NaF ameliorated the crystallinity and CEC of synthesized zeolite, but NaF had a better improvement effect. Na⁺ was considered to enhance the crystallization of zeolite, while F⁻ favored the dissolution of fly ash. The type of zeolite formed depended on the Si/Al ratio of the starting material prior to the nucleation and crystallization of zeolite. The adjustment of the Si/Al ratio of fly ash by addition of Na₂SiO₄ and Al(OH)₃ changed the type and CEC of zeolite. Waste solutions contained large amount of Si and little Al due to the formation of a zeolite named NaP1 in zeolite terminology with the Joint Committee of Powder Diffraction Standard (JCPDS) code of 39-0219. The alkalinity decreased largely. As a result, the CEC value of zeolite products synthesized with waste solution as alkali source decreased. The supplementation of new alkali to adjust the alkalinity of waste solution could enhance the CEC of synthesized product. It was concluded that: (1) addition of sodium halide and adjustment of the Si/Al ratio prior to synthesis can improve the quality of zeolite; (2) waste solutions produced following the zeolitization of fly ash can be reused as an alkali source in the activation of fly ash; zero-emission of waste solution in the synthesis of zeolite from fly ash is possible.     

Sulfur and carbon isotope geochemistry of coal and derived coal-combustion by-products: An example from an Eastern Kentucky mine and power plant

The isotopic compositions of S (δ³⁴S) and C (δ¹³C) were determined for the coal utilized by a power plant and for the fly ash produced as a by-product of the coal combustion in a 220-MW utility boiler. The coal samples analyzed represent different lithologies within a single mine, the coal supplied to the power plant, the pulverized feed coal, and the coal rejected by the pulverizer. The ash was collected at various stages of the ash-collection system in the plant. There is a notable enrichment in ³⁴S from the base to the top of the coal seam in the mine, with much of the variation due to an upwards enrichment in the δ³⁴S values of the pyrite. Variations in δ³⁴S and in the amount of pyritic S in the coal delivered to the plant show that there was a change of source of coal supplied to the plant, between week one and week two of monitoring, supporting a previous study based on metal and sulfide geochemistry for the same plant. The fly ash has a more enriched δ³⁴S than the pulverized coal and, in general, the δ³⁴S is more enriched in fly ashes collected at cooler points in the ash-collection system. This pattern of δ³⁴S suggests an increased isotopic fractionation due to temperature, with the fly ash becoming progressively depleted in ³⁴S and the flue gas S-containing components becoming progressively enriched in ³⁴S with increasing temperatures. Substantially less variation is seen in the C isotopes compared to S isotopes. There is little vertical variation in δ¹³C in the coal bed, with δ¹³C becoming slightly heavier towards the top of the coal seam. An 83–93% loss of solid phase C occurs during coal combustion in the transition from coal to ash owing to loss of CO₂. Despite the significant difference in total C content only a small enrichment of 0.44–0.67‰ in ¹³C in the ash relative to the coal is observed, demonstrating that redistribution of C isotopes in the boiler and convective passes prior to the arrival of the fly ash in the ash-collections system is minor.     

Mercury capture by selected Bulgarian fly ashes: Influence of coal rank and fly ash carbon pore structure on capture efficiency

Mercury capture by fly ash C was investigated at five lignite- and subbituminous-coal-burning Bulgarian power plants (Republika, Bobov Dol, Maritza East 2, Maritza East 3, and Sliven). Although the C content of the ashes is low, never exceeding 1.6%, the Hg capture on a unit C basis demonstrates that the low-rank-coal-derived fly ash carbons are more efficient in capturing Hg than fly ash carbons from bituminous-fired power plants. While some low-C and low-Hg fly ashes do not reveal any trends of Hg versus C, the 2nd and, in particular, the 3rd electrostatic precipitator (ESP) rows at the Republika power plant do have sufficient fly ash C range and experience flue gas sufficiently cool to capture measurable amounts of Hg. The Republika 3rd ESP row exhibits an increase in Hg with increasing C, as observed in other power plants, for example, in Kentucky power plants burning Appalachian-sourced bituminous coals. Mercury/C decreases with an increase in fly ash C, suggesting that some of the C is isolated from the flue gas stream and does not contribute to Hg capture. Mercury capture increases with an increase in Brunauer-Emmett-Teller (BET) surface area and micropore surface area. The differences in Hg capture between the Bulgarian plants burning low-rank coal and high volatile bituminous-fed Kentucky power plants suggests that the variations in C forms resulting from the combustion of the different ranks also influence the efficiency of Hg capture.     

Effects of coal fly ash amended soils on trace element uptake in plants

Variations in As, Ba, Bi, Cd, Co, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Th, Tl, U, W, and Zn uptake were evaluated in young, middle-aged, and mature basil, tomato, zucchini, and sunflower plants grown in soils amended with 5, 10, and 20% by weight fly ash. Elements susceptible to uptake with increasing fly ash were As and Tl, with As exceeding potentially toxic levels in basil and zucchini. Temporal variations in element uptake included (1) increasing Ba and Cd concentrations in tomato and As, Ba, Cd, and Tl in zucchini, (2) decreasing Co concentrations in tomato, zucchini, and sunflower, Ni in zucchini, and Tl in basil, and (3) increasing As and Ni concentrations in basil and Pb in zucchini and sunflower during early growth followed by decreasing concentrations at maturity. Although most of the trace elements were below reported toxic levels, the elevated concentrations of As in plant tissue suggests that fly ash treatment programs can lead to potentially toxic accumulations of As, and thus, should be carefully monitored.     

利用粉煤灰和电石渣制备形貌可控的硅酸钙晶须

粉煤灰和电石渣是重要的污染物,本文选用粉煤灰和电石渣为原料,通过水热合成法,制备了硅酸钙晶须材料,探讨了合成温度、保温时间、水固比和反应浓度等条件对生成产物晶须性能的影响,通过XRD和SEM等手段表征晶须的形貌和结构特征。结果表明,以工业品为原料时,温度控制在250℃左右,时间控制在30~50 h才能生成晶须产物。反应体系水固比应控制在40∶1且最佳反应浓度应控制在0.05 mol/L。不同类型的表面活性剂对硬硅钙石型硅酸钙晶须的形貌、长度和长径比都有影响。。     

Comparison of the effects of conventional organic amendments and biochar on the chemical, physical and microbial properties of coal fly ash as a plant growth medium

The bulk of fly ash (an inorganic waste of coal-fired power generation) produced is deposited in disposal areas where it needs to be revegetated. The effects of addition of three conventional organic amendments (biosolids, poultry manure, green waste compost), or poultry manure-derived biochar, to coal fly ash (at two rates) on some key chemical, physical and microbial properties and on growth of Rhodes grass (Chloris gayana) was studied in a laboratory incubation/greenhouse study. Addition of all amendments, including biochar, increased concentrations of extractable Mg, K, Na and P and CEC_{(pH 7.0)}. Additions of poultry manure, and particularly biosolids, also greatly increased levels of extractable NH₄ ⁺ and NO₃ ⁻-N. Addition of biosolids, green waste compost and biochar resulted in a decrease in macroporosity, a concomitant increase in mesoporosity and, at the high rate of addition, an increase in available water-holding capacity. Basal respiration was very low in fly ash and was increased by addition of all amendments; metabolic quotient was markedly greater in control than amended treatments. Biosolids, poultry manure and green waste compost additions all increased microbial biomass C. Growth of Rhodes grass was extremely low under unfertilized conditions in control, biochar and, to a lesser extent, green waste compost treatments but addition of poultry manure and the lower rate of biosolids resulted in large increases in yields. Although biochar additions increased extractable Ca, K, P, Cu, Zn and Mn, CEC, mesoporosity and water-holding capacity, they had a little or no stimulatory effect on the size of the soil microbial community, N fertility or plant growth. This was attributable to the lack of metabolisable C and an insignificant N-supplying capacity.     

The influence of fly and bottom ash deposition on the quality of Kastela Bay sediments

The objective of this study was chemical and radiological characterization of Kastela Bay sediments exposed to numerous anthropogenic sources like deposition of fly and bottom ash enriched in radionuclides and heavy metals, chemical plant, cement plant, iron plant, shipyard, electroplating facility, untreated industrial and domestic waste waters as well as heavy traffic. Totally, 33 samples of the mixture of fly and bottom ash, 12 sediment cores ranging from 0 to 40 cm and nine surface sediment samples were analyzed. Enrichment in heavy metals in the mixture of fly and bottom ash was ranging from 1.5 to 36 times compared to flysch soil while ²²⁶Ra and ²³⁸U were up to 50 times enriched compared to average activities characteristic for surrounding soils developed on the Middle and Upper Eocene flysch. Maximum ²³⁸U activity was approximately 32 times higher and ²²⁶Ra approximately 40 times higher in the Kastela Bay sediment compared to mean value determined for Adriatic sediments. The highest enrichment in sediment cores compared to background values were found for Zn (35.6 times), Pb (16 times), Cr (9.1 times) and Ni (4 times)     

Study on the distribution of PAHs in fly ash from coal and residual char combustion in a pressurized fluidized bed

Direct coal combustion not only has a low utilizing efficiency, but also produces a large amount of pollutants such as particulate, CO2, SO2, NOx, polycyclic aromatic hydrocarbons （PAHs）, PCDD/PCDFs, and so on. Coal gasification is a clean coal technology that presents good prospects for coal use, mainly for producing electricity with a high coal conversion efficiency and low environmental impact. However, there is a problem about the minimization of PAHs in coal gasification or direct coal combustion. PAHs are harmful to the environment and human health due to their high degree of mutagenicity and carcinogenicity when they enter human bodies through breathing, eating, and drinking. It is said that about 75%-90% cancers of human beings are mainly caused by PAHs. So the US EPA has prioritized 16 PAH compounds as hazardous air pollutants; these compounds are naphthalene （NAP）, acenaphthylene （AcPy）, acenaphthene （AcP）, fluorene （Flu）, phenanthrene （PhA）, anthracene （ANT）, fluoranthene （FluA）, pyrene （Pyr）, benzo （a） anthracene （BaA）, chrysene （Chr）, benzo （b） fluoranthene （BbF）, benzo （k） fluoranthene （BkF）, benzo （a） pyrene （BaP）, indeno（1,2,3,-cd） pyrene [In（1,2,3-cd） P], dibenzo （a,h） anthracene （DbA）, and benzo （ghi） perylene （BghiP）. The residual char is one of the main products during coal gasification, and then it is brought into the combustion chamber to combust. To investigate the distribution of PAHs in fly ash, the combustion of coal and residual char was tested in a pressurized spouted fluidized bed. After Soxhlet extraction and K-D concentration, the contents of 16 PAHs recommended by US EPA in coal, residual char, and fly ash, were analyzed by a HPLC coupled with fluorescence and diode-array detection.     

粉煤灰和二灰对桂林红黏土力学性质的影响

为了研究粉煤灰和二灰掺量及养护时间对桂林红黏土的改良效果,进行了直剪试验、固结试验以及电镜扫描试验。试验结果表明,粉煤灰的掺入提高了红黏土的抗剪强度,但超过一定量（18%粉煤灰掺量）反而会降低红黏土黏聚力,各掺量粉煤灰红黏土随养护龄期的延长,抗剪强度呈先增后缓趋势。二灰改良红黏土,在早期强度剧增,且强度随养护时间增长而大幅增加,一定龄期内,二灰红黏土黏聚力随二灰掺量呈先增后减趋势。粉煤灰和二灰的掺入均增大了红黏土的压缩模量,且随养护时间的延长而逐渐增大。红黏土中随粉煤灰、石灰的加入,发生一系列物理化学反应,从微观结构分析得知土中孔隙减少,结构性较素红黏土好。     

粉煤灰处理含氟废水的正交试验研究

对粉煤灰处理含氟废水进行了正交试验研究。结果表明各因素对F-去除率的影响顺序为:pH>V/M>T>CF-,极差R分别为49.6、9.1、4.9和3.6;在pH=5、V/M=10、T=3h时,粉煤灰对于CF-<500 mg/L的废水具有较好的去除效果;粉煤灰吸附F-的行为符合Langmuir等温方程,方程为Ce/qe=0.251 8Ce+6.087 3。     

Impact of petroleum coke characteristics on the adsorption of the organic fractions from oil sands process-affected water

Petroleum coke (PC) is a waste by-product generated during the oil upgrading processes by the petroleum industry. The continuing accumulation of large quantities of PC requires the development of innovative strategies for the effective utilization of this carbon-rich material. In this study, PC was used for the removal of naphthenic acids (NAs) and acid-extractable fraction (AEF) from oil sands process-affected water (OSPW), generated during the oil refining process. A systematic study on the adsorption of organic fractions, vanadium leaching from PC, adsorption mechanisms, and the effect of physico-chemical characteristics of the PC on adsorption process was performed. Physico-chemical properties of PC were determined by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy, and Brunauer–Emmett–Teller surface area analysis. AEF and NAs removals of 60 and 75 %, respectively, were achieved at PC dose of 200 g/L after 16 h of contact. FT-IR and TGA analysis of PC suggested the physisorption of organic compounds onto the surface of PC. The calculated mean free energy of adsorption (E < 8 kJ/mol) also indicated the physisorption of organics to the PC surface. The hydrophobic interactions between the NAs and the PC were suggested as the dominant adsorption mechanisms. The vanadium release occurred when PC was mixed with OSPW and vanadium concentration increased with an increase in the PC dose. Speciation analysis indicated that the vanadium leached was predominantly vanadium (V) and insignificant amount of vanadium (IV) was also detected.     

某电厂贮灰坝失稳过程及破坏机制研究

运用非饱和土土力学理论分析了某电厂贮灰坝失稳过程,揭示了该贮灰坝的失稳和破坏机制。分析表明,随着子坝挡水历时的增加,积水不断下渗,浸润线逐渐抬高,非饱和区域相应减少,坝体中受此影响的部位的孔隙水压力也随之不断增高,抗剪强度不断降低。此过程发展到一定程度,则导致贮灰坝产生破坏和滑动。上述分析清楚地诠释了干滩长期消失会使贮灰坝的稳定性遭受巨大威胁的原因。其研究结果可为贮灰坝、尾矿坝在类似工况下的稳定性评价和预测预报提供借鉴。     

Impact of fertilizer plant effluent on water quality

The impact of National Fertilizer Company of Nigeria outfall effluent on the physicochemistry and bacteriology of Okrika creek was investigated during the sampling period from May to December, 1998. The National Fertilizer Company of Nigeria outfall effluent, the Okrika creek water and the Ikpukulubie creek (control) water samples were collected. The physico-chemical parameters analyzed for all the samples included temperature, pH, total chloride, total dissolved solids, dissolved oxygen, conductivity, free ammonia, total phosphate, urea, zinc and iron, while the bacteriological determinations were total culturable aerobic heterotrophic bacteria count and identification of representative isolates. The Okrika creek recorded higher concentrations for all the physico-chemical parameters and bacteria load than the control creek. The higher values of pH, Free NH₃, urea, TDS and the conductivity of the National Fertilizer Company of Nigeria outfall effluent above the FEPA standards reflect the poor effluent quality generated by National Fertilizer Company of Nigeria. The bacteria species isolated from the samples include Aerococcus viridans, Alcaligenes faecalis, Bacillus cereus, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Serratia marcescens and Staphylococcus aureus. In general, the investigation revealed that there was an extremely adverse impact on the physico-chemical and bacteriological water quality characteristics of the Okrika creek as a result of the discharge of poor quality effluent from National Fertilizer Company of Nigeria operations.