An improved method of preserving and extracting mineral matter from coal by very low-temperature ashing (VLTA)

Shirazi, Ahmad Reza; Lindqvist, Oliver

doi:10.1016/0016-2361(93)90387-h

Cited by 13 publications

(4 citation statements)

References 3 publications

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“…The surface becomes covered with ash, which in some conditions can limit further ashing. This implied that particle size can influence the ashing rate and highlighted the importance of intermediate stirring and grinding of the samples during the ashing procedure . The results of the present study indicate that higher humificated peat was oxidized to a greater degree than lower humificated peat.…”

Section: Resultsmentioning

confidence: 48%

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Mechanisms Behind the Positive Effects on Bed Agglomeration and Deposit Formation Combusting Forest Residue with Peat Additives in Fluidized Beds

et al. 2009

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A compilation was made of the composition of peat from different areas in Sweden, of which a selected set was characterized and co-combusted with forest residue in controlled fluidized-bed agglomeration tests with extensive particle sampling. The variation in ash-forming elements in the different peat samples was large; thus, eight peat samples were selected from the compilation to represent the variation in peat composition in Sweden. These samples were characterized in terms of botanical composition, analyzed for ash-forming elements, and oxidized using a low-temperature ashing procedure, followed by characterization using scanning electron microscopy/electron-dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD). The selected peat samples had in common the presence of a small fraction of crystalline phases, such as quartz, microcline, albite, and calcium sulfate. The controlled fluidized-bed agglomeration tests that co-combusted forest residue with peat resulted in a significant increase in agglomeration temperatures compared to combusting forest residue alone. Plausible explanations for this were an increase of calcium, iron, or aluminum in the bed particle layers and/or the reaction of potassium with clay minerals, which prevented the formation of low-melting bed particle layers. The effects on particle and deposit formation during co-combustion were reduced amounts of fine particles and an increased number of coarse particles. The mechanisms for the positive effects were a transfer and/or removal of potassium in the gas phase to a less reactive particular form via sorption and/or a reaction with the reactive peat ash (SiO 2 and CaO), which in most cases formed larger particles (>1 μm) containing calcium silicon and potassium.

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Section: Resultsmentioning

confidence: 48%

“…The weight loss of the peat samples with high levels of iron was generally higher than that of the other peat samples. A study by Shirazi and Lindqvist demonstrated that, in low-temperature ashing, the particles are oxidized from the surface inward . The surface becomes covered with ash, which in some conditions can limit further ashing.…”

Section: Resultsmentioning

confidence: 99%

Mechanisms Behind the Positive Effects on Bed Agglomeration and Deposit Formation Combusting Forest Residue with Peat Additives in Fluidized Beds

et al. 2009

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“…Low-Temperature Ashing. The most widely used method for removing OM from coal and concentrating IM and MM in a low-temperature ash (LTA) is the oxygen plasma ashing at 150−200 °C. ,,− ,− Subsequently, the investigation of this IM residue by various chemical and mineralogical methods is conducted more easily than for the bulk coal samples. However, it should be stated that the LTA yield is not the actual IM or MM of coal because the LTA is derived from both IM and OM in coal, and inorganic compounds not originally present in coal (in particular for lignites) may be formed.…”

Section: Separation Proceduresmentioning

confidence: 99%

“…Scanning Electron Microscopy (SEM). This is one of the best methods for IM and MM characterization of coal, and data on the sample preparation and application of SEM can be found elsewhere. ,,,,,,,− ,,,,,,,,− ,− The high image quality in secondary and backscattered electrons at relatively higher magnifications (up to 10−20 thousand times) and the possibility to use microprobe elemental analyses of small areas (up to a few μm 2 ) to deduce mineral and phase species are a big advantage. SEM equipped with an energy-dispersive X-ray analyzer (EDX) or a wavelength-dispersive X-ray detector (WDX) can determine elements with atomic numbers from Na or B to U, respectively, in concentrations of ≥0.1−0.5%.…”

Section: Microscopic Observationsmentioning

confidence: 99%

Methods for Characterization of Inorganic and Mineral Matter in Coal: A Critical Overview

2003

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The present state of the methods commonly used for inorganic and mineral matter characterization in coal is described and summarized. The application of various separation procedures, macroscopic observations, reflected and transmitted optical microscopy, scanning and transmission electron microscopy, X-ray diffraction, differential thermal and thermogravimetric analyses, Mössbauer spectroscopy, infrared spectroscopy, and chemical analyses are briefly discussed. A short critical overview on the advantages and limitations of the above listed methods as well as some recommendations during their utilization are also presented.

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Analytical Aspects of Organomagnesium Compounds

Zabicky

2009

Patai's Chemistry of Functional Groups

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An improved method of preserving and extracting mineral matter from coal by very low-temperature ashing (VLTA)

Cited by 13 publications

References 3 publications

Mechanisms Behind the Positive Effects on Bed Agglomeration and Deposit Formation Combusting Forest Residue with Peat Additives in Fluidized Beds

Mechanisms Behind the Positive Effects on Bed Agglomeration and Deposit Formation Combusting Forest Residue with Peat Additives in Fluidized Beds

Methods for Characterization of Inorganic and Mineral Matter in Coal: A Critical Overview

Analytical Aspects of Organomagnesium Compounds

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