Evaluation of Acid-Leached Fly Ash as a Pozzolan

ABSTRACTDirect acid leaching (DAL) with HCl to recover Al and other metal values from fly ash has been examined extensively by the Electric Power Research Institute (EPRI) under RP2422. Large scale utilization of the solid residues from the DAL-process (DAL-residues) could significantly influence the economics of resource recovery. This paper describes a study of the potential use of DAL-residue as a pozzolan in the concrete industry.Samples of six ashes from a range of coal types were beneficiated to remove magnetic particles and particles larger than 45 gim. The beneficiated fractions were leached with 6M HCl at 105°C to determine metals recovery for Al, Fe, Ca, Mg, Na, K, and Ti. The corresponding DALresidues were characterized by chemical composition, morphology and mineralogical content, and examined as potential concrete pozzolans by standard ASTM tests. One DAL-residue from a highrank coal was examined more extensively in Portland cement mortars.The greatest yields of Al were from low-rank coal ashes, but were obtained at the ‘cost’ of substantial salt-cake production and high acid consumption. The DAL-residues from all ash types showed high-Si content: those from high-rank coals being spherical pseudomorphs of the original ash particles, and those from low-rank coals containing substantial quantities of gel-like materials.All of the residues were pozzolanic, but those from low-rank coals caused an unfavorable increase in water demand in mortars. DAL-residues from beneficiated high-rank coal ashes are enhanced pozzolans conforming to standard specification requirements with pozzolanic indices in excess of 100%.

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Correlations of Chemistry and Mineralogy of Western U.S. Fly Ash

MRS Proceedings ◽

10.1557/proc-86-109 ◽

1986 ◽

Vol 86 ◽

Cited By ~ 4

Author(s):

G. J. McCarthy ◽

O. E. Manz ◽

D. M. Johansen ◽

S. J. Steinwand ◽

R. J. Stevenson

Keyword(s):

Fly Ash ◽

Physical Properties ◽

North Dakota ◽

Data Center ◽

Low Rank ◽

Research Development ◽

X Ray Diffraction ◽

Fly Ashes ◽

X Ray ◽

Low Rank Coals

Fly ashes derived from low-rank coals mined principally in Montana, Wyoming and North Dakota are being studied by the Western Fly Ash Research, Development and Data Center [1]. Previous studies of the mineralogy of western U.S. fly ash by McCarthy et al. [1–3] using x-ray diffraction (XRD) form the framework of the present study. A database of chemical, mineralogical and physical properties, along with precursor coal characteristics, is being assembled. Based on studies to date of several hundred fly ash samples derived from lignite and subbituminous coals, as well as from several bituminous ashes, correlations of chemistry and mineralogy have been hypothesized and are being tested. These correlations are discussed below.

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Zero-shot Learning with Many Classes by High-rank Deep Embedding Networks

Proceedings of the Twenty-Eighth International Joint Conference on Artificial Intelligence ◽

10.24963/ijcai.2019/337 ◽

2019 ◽

Author(s):

Yuchen Guo ◽

Guiguang Ding ◽

Jungong Han ◽

Hang Shao ◽

Xin Lou ◽

...

Keyword(s):

Latent Variables ◽

Large Scale ◽

High Rank ◽

Low Rank ◽

Small Scale ◽

Simple Extension ◽

Linear Transformations ◽

Low Rank Approximation ◽

Deep Embedding ◽

Compatibility Function

Zero-shot learning (ZSL) is a recently emerging research topic which aims to build classification models for unseen classes with knowledge from auxiliary seen classes. Though many ZSL works have shown promising results on small-scale datasets by utilizing a bilinear compatibility function, the ZSL performance on large-scale datasets with many classes (say, ImageNet) is still unsatisfactory. We argue that the bilinear compatibility function is a low-rank approximation of the true compatibility function such that it is not expressive enough especially when there are a large number of classes because of the rank limitation. To address this issue, we propose a novel approach, termed as High-rank Deep Embedding Networks (GREEN), for ZSL with many classes. In particular, we propose a feature-dependent mixture of softmaxes as the image-class compatibility function, which is a simple extension of the bilinear compatibility function, but yields much better results. It utilizes a mixture of non-linear transformations with feature-dependent latent variables to approximate the true function in a high-rank way, which makes GREEN more expressive. Experiments on several datasets including ImageNet demonstrate GREEN significantly outperforms the state-of-the-art approaches.

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The influence of steam drying process on combustion behavior of Indonesian low-rank coals

Indonesian Mining Journal ◽

10.30556/imj.vol23.no2.2020.1105 ◽

2020 ◽

Vol 23 (2) ◽

pp. 105-115

Author(s):

Datin Umar ◽

◽

Suganal Suganal ◽

Ika Monika ◽

Gandhi Hudaya ◽

...

Keyword(s):

Ignition Temperature ◽

Calorific Value ◽

High Rank ◽

Low Rank ◽

Drying Process ◽

Combustion Behavior ◽

East Kalimantan ◽

Steam Drying ◽

Low Rank Coals

Steam drying process of the Low Rank Coals (LRCs) has been conducted to produce coal which is comparable with the High Rank Coal (HRC). Characterization of the raw and dried coals was carried out through proximate, ultimate, calorific value, Fourier Transform Infrared (FTIR) spectroscopy and Thermo Gravimetry-Differential Thermal Analysis (TG-DTA) to study the combustion behavior of the coals. This study used Indonesian low rank coals coming from Tabang (TKK coal) and Samurangau (SP coal), East Kalimantan. The results indicate that the calorific value of the dried coals increases significantly due to the decrease in moisture content of the coal. The FTIR spectrums show that the methylene-ethylene (RCH3/CH2) and aromaticity-aliphaticity ratios (Rar/al) of the dried coals increased while the ratio of RCO/ar decreased which reflect that the rank of the coals increased equivalent to the high rank coal (bituminous). Meanwhile, the TG-DTA indicates that the ignition temperature (Tig) and combustion rate (Rmax) of the dried coals increased. This analysis expresses that the dried coals produced by steam drying process have better combustion behavior due to the higher calorific value than those of the raw coals.

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Sulfides Formation in Carbothermic Reduction of Saprolitic Nickel Laterite Ore Using Low-Rank Coals and Additives: A Thermodynamic Simulation Analysis

Minerals ◽

10.3390/min9100631 ◽

2019 ◽

Vol 9 (10) ◽

pp. 631 ◽

Cited By ~ 1

Author(s):

Harjanto ◽

Rhamdhani

Keyword(s):

Carbothermic Reduction ◽

Simulation Analysis ◽

Thermodynamic Simulation ◽

Low Rank ◽

Nickel Laterite ◽

Metals Recovery ◽

Nickel Laterite Ore ◽

Nickel Grade ◽

Low Rank Coals ◽

Laterite Ore

In this paper, a systematic thermodynamic analysis of carbothermic reduction of saprolitic nickel laterite ore was carried out. Different carbon sources—such as pure C, sub-bituminous, and lignite—were used for the carbothermic reduction at 1000 °C (1273 K). The effect of the different additives—such as S, FeS, Na2S, Na2SO4, and CaSO4—was also systematically evaluated. The thermodynamic calculations suggested that the use of low rank coals (sub-bituminous and lignite) do not significantly affect the nickel grade and nickel recovery, but affect the total metals recovery. The presence of S in these C-sources promoted the formation of sulfides. At 1000 °C (1273 K), only a small amount of C-sources (C, sub-bituminous, lignite) are needed to significantly metallize the nickel in the laterite, i.e., between 4–6 wt %. The additives S, FeS, Na2S, Na2SO4, and CaSO4 were predicted to promote the formation of liquid sulfides, and at the same time reduce the formation of the (Fe,Ni) alloy, thus reducing the nickel and total metals recovery. Therefore, consideration is needed to balance the two aspects. The calculations predicted that S, Na2SO4, and CaSO4 additions provided an increase in the nickel grade; while FeS and Na2S reduced the nickel grade.

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Application of NMR in Coal Reservoir Characterization

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.765-767.2168 ◽

2013 ◽

Vol 765-767 ◽

pp. 2168-2171 ◽

Cited By ~ 1

Author(s):

Zi Yang ◽

Xiao Hua Pan ◽

Sheng Qiang Yuan ◽

Zhi Feng Ji

Keyword(s):

Nuclear Magnetic Resonance ◽

Reservoir Characterization ◽

High Rank ◽

Low Rank ◽

Main Peak ◽

Low Rank Coal ◽

Trimodal Distribution ◽

Porosity And Permeability ◽

Coal Reservoir ◽

Low Rank Coals

Nuclear Magnetic Resonance (NMR) can provide information about pore and fracture structures, porosity and permeability of reservoirs. It can deep into materials without destroying samples, with advantages such as rapid, accurate and high resolution. This paper introduced the experimental principles and carried out a series of NMR experiments based on high rank coal and low rank coal samples. Results show that: the T2 spectra of high rank coal samples have an independent trimodal distribution with the main peak located at the low T2 value section, indicating that high rank coal is dominated by micropores and transition pores; while the T2 spectrum of low rank coal samples show a continuous trimodal distribution with the main peak located at the high T2 value section, demonstrating the dominance of macropores, mesopores and fractures. The pore and fracture structures of low rank coals are significantly favorable than those of high rank coals.

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Elucidation of the Degradation of Poly Aromatic Hydrocarbon (PAH) in Coals During Pyrolysis

Energy and Environment Research ◽

10.5539/eer.v6n2p27 ◽

2016 ◽

Vol 6 (2) ◽

pp. 27

Author(s):

Andrew O. Odeh ◽

Samuel E Ogbeide ◽

Charity O Okieimen

Keyword(s):

Aromatic Hydrocarbon ◽

Pyrolysis Temperature ◽

Maximum Length ◽

High Rank ◽

Low Rank ◽

Transmission Electron ◽

Length Range ◽

Resistant Medium ◽

Crystallite Diameter ◽

Low Rank Coals

In this paper, we explore the use of high resolution transmission electron microscopy (HRTEM) in the degradation of the poly aromatic hydrocarbon (PAH) in coals of different ranks subjected to chemical plus heat treatment. The crystallite diameter on peak (10) approximations, La (10), of 37.6 Å for the high rank coal char at 700 oC fell within the HRTEM’s range of minimum-maximum length boundary of 11 x 11 aromatic aromatic fringes (28 – 44 Å). The La (10), 30.5 Å for the low rank lignite chars fell nearly on the minimum-maximum length range of 7 x 7 aromatic fringes (17 – 28 Å).The HRTEM results showed that the high rank anthracite chars at 700 oC comprised a higher distribution of larger distribution of larger aromatic fringes (11 x 11 parallelogram catenations). The mechanism for the similarity between coal chars of different ranks was the greater transition occurring in the low rank coals (lignite and sub-bituminous) to match the more resistant medium and high rank coals (bituminous – anthracite). This emphasized that the transitions in the properties of the low rank coals were more thermally accelerated than those of the high rank coals. The total PAHs detected in the coals of different ranks during pyrolysis are dominated by two- and three- ring PAHs. The amount of PAHs increase and then decrease with increase in pyrolysis temperature.

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