Real Fly Ash Research Articles

Particulate Deposition Effects on Internal Swirl Cooling of Turbine Blades

Abstract Particulate deposition effects on flow and heat transfer in an internal swirl tube subjected to fly ash ingestion were investigated by constructing an unsteady simulation framework, in which a particle–wall interaction model and a mesh morphing technique were implemented. Swirling flows in the swirl tube were induced by two tangential jet nozzles. Particles having a mean diameter of 6.5 μm were released from the nozzle inlets to model an exposure duration of 4500 h for engine operation in real fly ash environment using scale factors in the unsteady simulations. Particle deposition and its dynamic process were examined, and the effects of deposition on the swirling flow were quantified by comparing time-averaged velocity profiles, vorticity, pressure loss, and heat transfer with those from a clean tube without deposition. Results reveal that the most upstream section of the swirl tube captures the majority of the particles and the deposition distributions show a spiral pattern over the tube wall. The total mass of the deposits within the tube linearly increases, while local deposition thickness has a nonlinear relationship with the exposure time due to the interaction of the particles with the swirling flow. The deposition can generate a maximum of 15% reduction in cross-sectional area of the tube within the exposure duration, resulting in a reduced swirl number, because of the accelerated axial velocity and the decreased circumferential velocity, and further lower heat transfer in the downstream section of the tube relative to the clean tube case. However, as the heat transfer in the upstream deposition section is enhanced by the roughness due to the deposition, area-averaged heat transfer throughout the entire swirl tube is slightly improved by 4.0% but simultaneously a 179% higher pressure loss is observed, leading to an overall thermal performance value of 0.79 (relative to 1.0 for a clean tube), indicating substantial degradation of cooling performance in the fouled swirl tube.

Municipal Solid Waste as Secondary Resource: Selectively Separating Cu(II) from Highly Saline Fly Ash Extracts by Polymer-Assisted Ultrafiltration

Urban mining from fly ash resulting from municipal solid waste incineration (MSWI) is becoming more and more important due to the increasing scarcity of supply-critical metals. Metal extraction from acid fly ash leaching has already been established. In this context selective Cu recovery is still a challenge. Therefore, our purpose was the separation of Cu(II) from MSWI fly ash extracts by polymer-assisted ultrafiltration (PAUF). We investigated three polyethyleneimines (PEIs) with regard to metal retention, Cu(II) selectivity, Cu(II) loading capacity, and the viscosity of the PEI containing solutions. A demanding challenge was the highly complex matrix of the fly ash extracts, which contain up to 16 interfering metal ions in high concentrations and a chloride content of 60 g L−1. Overcoming that, Cu(II) was selectively enriched and separated from real fly ash extract at pH 3.0. At pH 1.0, a PEI-free Cu(II) concentrate was obtained and PEIs could be regenerated for reuse in further separation cycles. The PAUF conditions developed at laboratory scale were successfully transferred to pilot scale, and hyperbranched PEI (HB-PEI) was found to be the most suitable reagent for PAUF in a technical scale. Moreover, HB-PEI enables photometric control of the Cu(II) enrichment.

A novel method for precise measurement of unburnt carbon in boiler fly ash by ECSA® based on TG-MS

The unburnt carbon content of fly ash is an important index for evaluating the combustion efficiency of boilers. Measurement by traditional loss-on-ignition (LOI), approximate and elemental analyses causes large errors due to mixing minerals such as portlandites, carbonates, or sulfates with the unburnt carbon. In this paper a new method of Equivalent Characteristic Spectrum Analysis (ECSA®) based on Thermogravimetric Mass Spectrometry (TG-MS) was adopted to determine the unburnt carbon in fly ash. The measuring mechanism, accuracy, superiority, sensitivity, and reliability of ECSA® were discussed. The intrinsic measuring mechanism of ECSA® and its sensitivity were explored through analyzing the reaction characteristics of model compounds that were used to simulate the real fly ash. Five types of real fly ashes collected from boiler plants were used to calibrate and verify the reliability and accuracy of ECSA® method. The ECSA® was finally validated to be more precise and accurate by improving 2 to 3 orders of magnitude in error compared with the LOI and elemental analysis on determining the unburnt carbon in fly ash, and can provide reliable information to assess the operating status of boilers.

Determination of hexachlorobutadiene, pentachlorobenzene, and hexachlorobenzene in waste incineration fly ash using ultrasonic extraction followed by column cleanup and GC-MS analysis.

Hexachlorobutadiene (HCBD) was listed as a new controlling persistent organic pollutant in the Stockholm Convention because of its wide industrial applications and potential genotoxicity and carcinogenicity. However, only limited information exists on the release of HCBD from unintentional sources, such as waste incineration. Identification and quantification of HCBD in fly ash, one of the major outputs of waste incineration, is imperative. This work presents a simple method for determining HCBD in waste incineration fly ash based on ultrasonic extraction coupled with a silica gel-Florisil column cleanup followed by gas chromatography-mass spectrometry detection. Two typical persistent organic pollutants, pentachlorobenzene (PeCB) and hexachlorobenzene (HCB), were measured simultaneously. The parameters that influence the extraction efficiency and the quality of instrument detection were studied. Under the optimum experimental conditions, high sensitivity (detection limit 0.25-0.53 ng g-1), acceptable recoveries (64.0-71.4%) at spiking levels of 5-500 ng g-1, and good repeatability [relative standard deviation (n = 3) of 14% or less] were achieved for all target analytes. The validation of this method was performed by analysis of six real fly ash samples from different waste incinerators in eastern China. The concentrations of HCBD detected in these samples (1.39-97.6 ng g-1) were comparable to those of PeCB (1.22-150 ng g-1) and HCB (0.82-120 ng g-1), indicating that the residual HCBD as well as PeCB and HCB in waste incineration fly ash should not be ignored. The results confirm for the first time that waste incineration is an unintentional source of HCBD in China. Graphical abstract An analytical method for hexachlorobutadiene, pentachlorobenzene, and hexachlorobenzene in fly ash from waste incineration. GC-MS gas chromatography-mass spectrometry, Ph-d10 phenanthrene-d10.

Formation of persistent chlorinated aromatic compounds in simulated and real fly ash from iron ore sintering

Effects of carbon concentration and Cu additive in simulated fly ash (SFA) and real fly ash (RFA) on the formation of polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzo-p-dioxins (PCDDs), chlorobenzenes, and polychlorinated biphenyls which were all regarded as persistent chlorinated aromatics in iron ore sintering were investigated. In the annealing process of SFA with various carbon contents, the yield of chlorinated aromatics and the I-TEQ obtained their maximum at 10 wt% carbon content. Active carbon in SFA acted as the carbon source as well as an adsorbent which led to higher production of PCDD/F in solid phase at 10 wt% carbon content. The increase of carbon content will be beneficial on the formation of 2,3,7,8-Chloro-substituted PCDF compared with 2,3,7,8-Chloro-substituted PCDD. In addition, the CuCl2·2H2O was a much more powerful catalyst in the formation of chlorinated aromatic compounds compared with elementary Cu, since it served as both a catalyst and a chlorine donor. However, the RFA behaved similarly with SFA with elementary Cu in the formation of chlorinated aromatic compounds. The effect of carbon content and copper additives on formation of 2,3,7,8-chloro-substituted congeners displayed similar characteristics with the tetra- to octa-PCDD/F isomers and even the total PCDD/Fs.

Formation of persistent chlorinated aromatic compounds in simulated and real fly ash from iron ore sintering

Formation of persistent chlorinated aromatic compounds in simulated and real fly ash from iron ore sintering

Synergetic inhibition of thermochemical formation of chlorinated aromatics by sulfur and nitrogen derived from thiourea: Multielement characterizations

Nitrogen and sulfur (N/S)-containing compounds inhibit the formation of polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs) in thermal processes. However, few studies have examined the inhibition mechanisms of N/S-containing compounds. In the present study, we focused on thiourea [(NH2)2CS] as such a compound and investigated its inhibition effects and mechanisms. The production of PCDD/Fs, polychlorinated biphenyls (PCBs), and chlorobenzenes (CBzs) were inhibited by >99% in the model fly ash in the presence of 1.0% thiourea after heating at 300°C. Experimental results using real fly ash series were indicative of the thermal destruction of these chlorinated aromatics by thiourea. Multielement characterization using K-edge X-ray absorption fine structures of copper, chlorine, sulfur, nitrogen, and carbon revealed three possible inhibition paths, namely, (a) sulfidization of the copper catalyst to CuS, Cu2S, and CuSO4; (b) blocking the chlorination of carbon via the reaction of chlorine with N-containing compounds to generate ammonium chloride and other minor compounds; and (c) changing the carbon frame involved in attacking the carbon matrix by sulfur and nitrogen. Thus, thiourea plays a role as a sulfur and nitrogen donor to achieve multiple and synergistic inhibition of chlorinated aromatics. Our results suggest that other N/S-containing inhibitors function based on similar mechanisms.

Mechanism of unintentionally produced persistent organic pollutant formation in iron ore sintering

Effects of temperature, carbon content and copper additive on formation of chlorobenzenes (CBzs) and polychlorinated biphenyls (PCBs) in iron ore sintering were investigated. By heating simulated fly ash (SFA) at a temperature range of 250–500°C, the yield of both CBzs and PCBs presented two peaks of 637ng/g-fly ash at 350°C and 1.5×105ng/g-fly ash at 450°C for CBzs, and 74ng/g-fly ash at 300°C and 53ng/g-fly ash at 500°C. Additionally, in the thermal treatment of real fly ash (RFA), yield of PCBs displayed two peak values at 350°C and 500°C, however, yield of CBzs showed only one peak at 400°C. In the thermal treatment of SFA with a carbon content range of 0–20wt% at 300°C, both CBzs and PCBs obtained the maximum productions of 883ng/g-fly ash for CBzs and 127ng/g-fly ash for PCBs at a 5wt% carbon content. Copper additives also affected chlorinated aromatic formation. The catalytic activity of different copper additives followed the orders: CuCl2∙2H2O>>Cu2O>Cu>CuSO4>CuO for CBzs, and CuCl2∙2H2O>>Cu2O>CuO>Cu>CuSO4 for PCBs.

Fly ash as an assemblage of model Ca–Mg–Na-aluminosilicate glasses

Model Ca–Mg–Na-aluminosilicate glasses based on compositions found in a calcareous fly ash were synthesised and their reactivity assessed in NaOH solution and in Portland cement paste. It was found that the reactivity followed the same trend in both systems and that the reaction of the glasses in pastes was very similar to that of the components of similar composition in the real fly ash. This finding indicates that the reactivity of glass in cement can be directly linked to the chemical composition of the glass. Further, when the reactivity of the glasses was normalized to their surface area, it was found that there exists a strong correlation with the NBO/T, the ratio of non-bridging oxygens and tetrahedral ions in the glass.

Upgrading of positively buoyant particles using an Inverted Reflux Classifier

This paper is concerned with the separation of cenosphere particles from fly ash. Cenospheres are hollow alumina silicate micro-shells found in fly ash. They are positively buoyant in water, thus allowing gravity-separation to be used to achieve separation from negatively buoyant fly ash particles. In this study an Inverted Reflux Classifier, a combination of parallel inclined channels and a vertical fluidized bed, was used for the first time to recover and concentrate cenospheres from a real fly ash feed obtained from a coal fired power station. The effects of different operating parameters such as the feed rate, product rate, and fluidization rate were investigated. The device was fed at a solids flux of about 2600kg/(m2h). A product grade of 76% was achieved from a feed with a grade of only 0.51%, corresponding to an upgrade of 149. Here, the recovery of the cenospheres was 42%. By increasing the overflow product rate, a significantly higher recovery of 64% was achieved, but at a reduced upgrade of 33. In both cases most of the losses were attributed to the relatively fine cenosphere particles being entrained to the underflow.

Do we underestimate the impact of particles in coal-derived flue gas on amine-based CO2 capture processes?

The effect of particulate matter on the amine-based capture process has, up till now, not been considered in much detail due to the relatively low concentration of particulate entering the capture plant. In this study we present results of leaching tests with 30 wt% MEA utilising real fly ash samples from a range of European coal-fired power plants. The effect of a number of parameters including CO2 loading, temperature, pH, leaching time, solid/liquid ratio & organic heat stable salts have been investigated. These experiments show that the behaviour of the various compounds and elements is not uniform with different conditions. A strong correlation between reducing pH/increasing CO2 loading and Fe, Cr & V levels is observed, but is not seen for other heavy metals. This impact of pH on metal solubility is striking and suggests that Fe, in particular, may be transported by the liquid system and stored as deposits in the stripper where increased pH reduces the solubility of Fe compounds. The presence of oxalate as a heat stable salt leads to the precipitation of calcium oxalate when calcium phosphate is leached out of the ash. This could result in deposits in areas such as the reboiler that may lead to plugging, reduced heat transfer efficiency and even corrosion issues. Solid/liquid ratio was also found to have some effect with lower solid/liquid ratios showing higher relative solubility for heavy metals. Temperature and leaching time were also investigated but only minor increases in metals content were observed by increasing either of these parameters. The results observed strongly suggest that the effects of particulate matter on the post-combustion capture process should not be ignored, particularly if levels are sufficient to lead to significant build up of ash in the solvent. Ash captured in the liquid has the potential to release significant amounts of Fe, Mg, Ca and PO4 being a concern for the enhancement of solvent degradation processes.

Impact of oxy-fuel combustion on fly ash transformations and resulting corrosive behavior of alloys 310 and 617

Within fireside corrosion tests performed at University of Stuttgart, two alloys dedicated for ultra-supercritical boilers were chosen for a series of tests under oxy-fuel conditions at a metal temperature of 650°C and 750°C. Three real fly ash deposits and three minerals well-known from coal combustion were considered. The fireside corrosion was studied having in focus interactions between flue gas atmosphere, deposits and alloys during oxy-fuel firing with 0,5% SO2 and exposure time of 350h.

Nickel-base superalloys for ultra-supercritical coal-fired power plants: Fireside corrosion. Laboratory studies and power plant exposures

The aim of the study was to determine the fireside corrosion performance of certain nickel-base superalloys dedicated for construction of superheater and reheater sections of a boiler operating at advanced ultra-supercritical conditions. For this purpose, three nickel-base alloys varying in chromium content from 20% to 25% (Alloys 263, 617 and 740) were selected for laboratory tests up to 1000h. Additionally, the chosen materials were exposed using a temperature-controlled corrosion probe in a 500kWth pulverized fuel test rig, one lignite-fired and two hard-coal-fired power plants. The specimens’ temperatures were in the range 640–760°C. The fireside corrosion was studied having in focus the synergy effect of combustion gas atmosphere, real fly ash deposits and alloy composition. Corrosion behavior of each alloy was determined using dimensional metrology and the obtained results were compared with data available from the literature.The values measured on the samples exposed in power plants fit well with the numbers generated from the laboratory tests performed at 24, 350 and 1000h. Moreover the values are in good agreement with results found in the literature and similar alloy ranking based on corrosion resistance is confirmed by the literature. Clear sulphur-induced corrosion was noticed after 1000h exposures in the laboratory furnaces at only one of the examined alloys, which is characterized by the highest molybdenum and lowest titanium content. Both of these elements are believed to play a significant role in the corrosion behavior of the examined alloys. In some metal rings exposed in power plants sulphur induced corrosion is witnessed.In contrast to iron-base austenitic steels no straight connection is observed between increasing chromium content and improved corrosion resistance in the nickel-base austenites. Intergranular oxidation with participation of alumina repeats and occasionally leads almost to a grain release. In laboratory conditions fly ash appears to partially inhibit the corrosive influence of the gas atmosphere, since it behaves to a certain extent as a protective barrier for the metal surface while acting as a “sulphur sink”.

Recovery of germanium from real fly ash leachates by ion-exchange extraction

Germanium recovery from real fly ash (FA) leachates was studied using ion-exchange procedures. The procedure was based on germanium complexation with catechol (CAT) in an aqueous solution followed by the retention of the Ge–CAT complex onto a conventional strongly basic anionic resin (IRA-900). A centred composite rotatable design (CCRD) with two factors was employed for experimental design and analysis of the results. The factors examined during sorption tests were CAT amount and resin dosage. Optimum values of these parameters were: a CAT/Ge molar ratio of 9 and resin/Ge dosage of 3, obtaining 96.1% germanium retention. The obtained response surface and mathematical model are significant with high correlation coefficients ( R 2 = 0.8794). The maximum amount of retained germanium was calculated to be 215.5 mg/g resin. The elution of the germanium complex was achieved with acid solutions in an ethanol matrix.

Real-Time Gas-Phase Analysis of Mono- to Tri-Chlorobenzenes Generated from Heated MSWI Fly Ashes Containing Various Metal Compounds: Application of VUV-SPI-IT-TOFMS

We measured sensitive real-time change of low-chlorinated (Cl(1)-Cl(3)) benzenes in gas phase from heated model and real solid samples using the recently developed vacuum ultraviolet (VUV) single-photon ionization (SPI) ion trap time-of-flight mass spectrometer (VUV-SPI-IT-TOFMS). Model solid samples that contained activated carbon, potassium chloride, silicon dioxide, and trace metallic compounds (copper, iron, lead, and zinc) were used to simulate fly ash at a municipal solid waste incinerator (MSWI). The concentrations of chlorobenzenes determined by integrating the area for 30 min using VUV-SPI-IT-TOFMS were correlated with gas-phase concentrations analyzed by GC/MS. Real-time changes had characteristic patterns dependent on metal species and compounds. Comparing gas-phase real-time patterns of low-chlorinated benzenes between real and model fly ashes, copper chloride- and oxide-like compounds in real fly ash at the postcombustion zone in a MSWI may play key factors in the formation of low-chlorinated benzenes. Lead and zinc compounds and iron oxide in solid phase did not affect the formation of low-chlorinated benzenes in gas phase. VUV-SPI-IT-TOFMS can be applied to the time-dependent characterization of volatile low-chlorinated benzenes in gas phase in various artificial and environmental processes.

Influence of Cu, Fe, Pb, and Zn Chlorides and Oxides on Formation of Chlorinated Aromatic Compounds in MSWI Fly Ash

Model fly ashes containing admixed Cu, Fe, Pb, and Zn chlorides and oxides were heated at a temperature corresponding to the postcombustion zone of a municipal solid waste incinerator (MSWI), resulting in the formation of chlorinated aromatic compounds, including polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs), polychlorinated biphenyls (PCBs), and chlorobenzenes (CBzs). The concentrations of these compounds were measured and compared with those occurring in real fly ash. The order with respect generative capacity of each metal additive was calculated from principal component analysis of the concentrations of the different chlorinated aromatic compounds as CuCl(2)*2H(2)O > Cu(2)(OH)(3)Cl > FeCl(3)*6H(2)O > FeCl(2)*4H(2)O > CuO > Fe(2)O(3) > PbCl(2) > blank (no metal added) > ZnCl(2) > PbO > ZnO. From hierarchical cluster analysis of the concentrations and congener distribution patterns of the PCDDs, PCDFs, PCBs, and CBzs, the metallic compounds were divided into five groups: Group A (CuCl(2)*2H(2)O and Cu(2)(OH)(3)Cl), B (FeCl(3)*6H(2)O and FeCl(2)*4H(2)O), C (CuO and PbCl(2)), D (Fe(2)O(3), blank, and ZnCl(2)), and E (PbO and ZnO). Cluster analysis showed the congener distribution patterns of model fly ashes to be similar to the pattern of real MSWI fly ash. The formation of PCDDs was influenced mainly by group B, blank, and PbO; PCDFs, mainly by CuO, Fe(2)O(3) and ZnCl(2); PCBs, mainly by groups B and C; and CBzs, mainly by groups A and B. Thus, the multiple promotion of chlorinated aromatic compound formation by metallic chlorides and oxides in the fly ashes of MSWIs and other thermal processes has considerable importance for the environment.

Relationship between dynamic change of copper and dioxin generation in various fly ash

Only limited information on the chemical forms of copper in municipal solid waste incinerator (MSWI) fly ash is available in the literature. Therefore, we performed in situ X-ray absorption near-edge spectroscopy (XANES) experiments involving two types of real fly ash to confirm the behavior of copper in fly ash at secondary formation temperatures for polychlorinated dibenzo- p-dioxins (PCDDs) and dibenzofurans (PCDFs). CuCl 2 · 3Cu(OH) 2 was detected in both fly ash types before heating experiments. Cupric compounds in real fly ash were reduced to cuprous compounds or elemental copper at approximately 200 °C. The changes in the Cu XANES spectra observed for the two fly ash samples were similar to those observed previously. We also examined the behavior of copper in model fly ash using SiO 2 to investigate the effect of supporting materials and copper content in fly ash on the dynamic changes of copper and amount of dioxins generated. There was little difference between the use of boron nitride (BN) and SiO 2 as a supporting material. The formation mechanisms of PCDDs and PCDFs in both of the model fly ash types were basically the same. Thus, we conclude that the dynamic change of copper in MSWI fly ash during heating is a commonly observed feature, and no simple relationship between the composition of fly ash and the amount of PCDD/PCDF generated or dynamic change of copper is apparent. The dynamic change of copper explained the generated amount and homologue distribution of PCDDs and PCDFs.

Is the natural PCDD/PCDF mixture toxic for human placental JEG-3 cell line? The action of the toxicants on hormonal profile, CYP1A1 activity, DNA damage and cell apoptosis

The present study was conducted to define the action of a mixture obtained by the extraction and purification of real fly ash, on specific toxicity endpoints, such as hormonal secretion, CYP1A1 expression, DNA damage and cell apoptosis. JEG-3 cell line was exposed in vitro to different doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or Polychlorinated dibenzo-p-dioxin/Polychlorinated dibenzo-P-furan (PCDD/PCDF) mixture. Both TCDD and the mixture decreased hCG secretion, while inhibition of progesterone levels was noted only under the influence of TCDD. The changes in hormone production were not due to the action on cell viability. There were time-dependent differences in CYP1A1 expression in cells exposed to TCDD and PCDD/PCDF mixture. Both TCDD and PCDD/PCDF mixture did not induce the DNA damage, as evaluated by the comet assay. Significantly lower DNA migration from the head of comet into the comet tail was noted after the removal of reagents. The highest efficiency of this process was noted 4 h after the TCDD and 24 h after the PCDD/PCDF mixture removal. These results suggest that the DNA adducts and/or DNA-DNA cross-links were formed. Neither TCDD nor PCDD/PCDF mixture had any effect on cell apoptosis assessed by caspase-3 activity and Hoechst 33258. Taken together, these findings clearly indicate a weaker action of the mixture when compared with TCDD. However, in both cases, their action was not due to the induction of the DNA damage and subsequent cell apoptosis but due to a direct influence of these toxicants on placental hormone production.

Degradation of PCDD/Fs by mechanochemical treatment of fly ash from medical waste incineration

The potential of mechanochemical treatment (MC) to degrade PCDD/Fs contained in fly ash was tested via grounding with and without calcium oxide (CaO) under atmospheric pressure. Three types of fly ash collected from medical waste incineration were compared, originating either from rotary kiln fluidized bed multi-stage incinerator using activated carbon spray (FA1, FA2), or a simple stoker incinerator without activated carbon spray (FA3). In test I: CaO to FA1 mixed at ratio of 6–60% was milled at rotational speed of 350 rpm; in test II: FA2 and FA3 without CaO were milled at rotational speed of 400 rpm. The duration of the tests was 2 h. The results from the present study indicate that (1) under two test conditions of with and without CaO, PCDD/Fs contained in real fly ash both can be degraded by mechanochemical treatment, (2) under condition of blending with CaO, the degradation efficiency of PCDD/Fs increased with increasing ratio of CaO, (3) the degradation efficiency of PCDD/Fs may increase with rotational speed increasing and (4) the destruction and dechlorination are major mechanism for PCDD/Fs degradation. These results show that mechanochemical treatment is a high potential technology for PCDD/Fs degradation in fly ash.

Modeling of Leaching Surface Evolution in Stressed Particulate Media

Many reuse scenarios of waste as construction aggregates involve the application of load. The leachability of contaminants from aggregates is affected by the exposed surface area of constituent particles. Loading decreases interparticle porosity and permeability of bulk materials but enlarges particle-to-particle contacts. A model that accounts for the effects of particle deformation on exposed surface area of particles is developed herein and applied to fly ash. Brunauer, Emmett, and Teller (BET) measurements of the specific surface area of fly ash were compared with those of glass beads and theoretically generated data for spherical particles of equivalent diameter. The ratios of the BET-measured specific surface areas of the glass beads to the theoretically calculated values (TCV) in the same size ranges were found to range from 2 to 11, while those of wet-sieved and dry-sieved fly ash to the TCV ranged from 30 to over 2,825. Plausibly, internal porosities, surface asperities, and shape irregularities of real fly ash particles account for their higher specific surface area values relative to that of size-equivalent glass beads. The effects of surface area evolution on leachability of contaminants were demonstrated using experimental leaching data obtained for Cu, Se, and As. Using contaminant leaching coefficient data, it was found that stress level has minimal effects on the leachability of Cu. Leaching coefficients of Se and As were found to increase with an increase in load. Although the values for Se are comparable to column leaching data at stress levels smaller than 1,425 kPa, they are much higher at 5,710 kPa than column leaching data. In the case of As, the leaching coefficients are smaller under load than those of column leaching. Leaching coefficients measured on the basis of BET-measured specific surface areas are smaller than those based on calculated specific surface areas by a factor of about 10,000. Models that incorporate the effects of load, surface asperities, and internal porosities into surface area estimates are proposed and demonstrated for ash of known physicochemical characteristics and reuse scenarios.