The Study of Hydration and Carbonation Reactions and Corresponding Changes in the Physical Properties of Co-Deposited Oil Shale Ash and Semicoke Wastes in a Small-Scale Field Experiment

Sedman, Annette; Talviste, Peeter; Kirsimäe, Kalle

doi:10.3176/oil.2012.3.07

Cited by 8 publications

(5 citation statements)

References 15 publications

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“…In the high temperature range, the pyrolysis reaction of kerogen inside the oil shale is basically completed . But a series of physical and chemical interactions also can happen, which include the dehydration of some crystalline water and decomposition of the residual inorganic minerals, and some fixed carbon undergoes coking carbonization to form shale semicoke. ,, Although the growth of pore volume slows down, the porosity, TNF, and MAF continue to increase because thermal cracking intensifies under high temperature.…”

Section: Results and Discussionmentioning

confidence: 99%

Evolution of Pore and Fracture Structure of Oil Shale under High Temperature and High Pressure

et al. 2017

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In order to study the coupled effect of the temperature and pressure on pyrolysis characteristics and pore and fracture structures of oil shale, a total of 25 groups of pyrolytic reaction experiments have been conducted on 14 mm long and 7 mm in diameter cylindrical oil shale specimens under different temperature and pressure conditions ranging from 20 to 600 °C and 0.1–15 MPa. Further, both X-ray microcomputed tomography (μCT) and mercury intrusion porosimetry (MIP) have been used to comprehensively investigate the network structure, interconnectivity, and evolution of pore and fractures. The results show that the temperature significantly affects the pyrolysis characteristics of oil shale. With rising temperature, both the mass loss and the porosity increase gradually, the number and the maximum aperture of fractures also increase, and the pyrolytic degree intensifies progressively. The increase is most significant from 300 to 500 °C. The maximum mass loss ratio is 20.84%, the largest porosity is 13.52 times larger than that under the room temperature, and the total number and the maximum aperture of the fractures are 813 and 0.383 mm, respectively. Moreover, the pressure has a significant effect on the pore and fracture structures of oil shale. As the pressure increases, both the pore volume and the fracture distributions first decreased and then increased. With the continuous increase of pressure, the porosity and the total number of fractures reach a maximum at the pressure of 15 MPa. Under the coupled effect of temperature and pressure, with both the temperature and pressure increasing, the pores and fractures in the oil shale specimens developed increasingly. Furthermore, using the μCT scan technology, the distribution laws and the connectivity characteristics of the pores and fractures have been investigated. The connected fractures appear when the temperature reaches 300 °C and further extend along the bedding plane or pass through it at 600 °C.

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Section: Results and Discussionmentioning

confidence: 99%

Evolution of Pore and Fracture Structure of Oil Shale under High Temperature and High Pressure

et al. 2017

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“…In the water-mixed samples, the secondary Ca-Al-sulphate phase (ettringite) and the Ca-Alphase (hydrocalumite) also started to precipitate. Formation of ettringite and hydrocalumite is a characteristic process in the hydrated oil shale ash and semicoke deposits [5,8,[15][16][17]. Sulphate needed for ettringite formation was possibly delivered by the CaS dissolution that disappeared quickly after the beginning of our experiments.…”

Section: Hydration Geopolymerization and The Development Of Compressmentioning

confidence: 99%

Geopolymeric Potential of the Estonian Oil Shale Solid Residues: Petroter Solid Heat Carrier Retorting Ash

Paaver¹,

Paiste²,

Kirsimäe³

2016

Oil Shale

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In this paper, the geopolymerization of the solid heat carrier (SHC) ash waste produced at Petroter shale oil plants, Viru Keemia Grupp (VKG), Estonia was studied. Different mixtures were prepared to study and evaluate the potential use of this SHC ash for geopolymer-type mortar and cement production and to compare alkali-activated black ash with the material having self-cemented upon hydration with plain water. Mixtures prepared with plain water and NaOH solution show comparable compressive strength development, but the mixture with NaOH affords significantly lower compressive strength values, which can be explained by the absence of an ettringite/monosulphate phase in the NaOH-activated samples. Hydrocalumite precipitated instead of ettringite in the NaOH-activated mixture does not provide the interlocking structure that is found in water mixtures, though the formation of an amorphous geopolymer phase is possibly observed in the NaOH-activated sample after 90 days of curing. Sodium silicate-and Na-silicate/NaOH-activated samples show a strong geopolymerization and development of Ca-Na-Al-silicate gel formed in the pore space of the ash aggregate. However, due to strong shrinkage upon drying, the compressive strength obtained after 7 days of curing is lost in the prolonged curing process, and further research into the causes and prevention of Ca-Na-Al-silicate gel shrinkage is needed.

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“…In parallel with anhydrite dissolution, the precipitation of the Ca-sulphoaluminate hydrate phase, ettringite, is initiated and continues for 6–7 days [ 46 ]. Paaver et al [ 25 ] showed that ettringite composes up to 20% of minerals in hydrated pastes of the activated FA already after seven days, whereas ettringite abundances up to 40% have been reported in oil-shale processing waste deposits [ 47 , 48 , 49 ]. Dissolution of anhydrite, slacking of the lime, and formation of abundant ettringite is also evident in FA-CSA mixtures with OPC and sand ( Figure 2 ).…”

Section: Resultsmentioning

confidence: 99%

Design of High Volume CFBC Fly Ash Based Calcium Sulphoaluminate Type Binder in Mixtures with Ordinary Portland Cement

2021

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Growing concerns on global industrial greenhouse gas emissions have boosted research for developing alternative, less CO2 intensive binders for partial to complete replacement of ordinary Portland cement (OPC) clinker. Unlike slag and pozzolanic siliceous low-Ca class F fly ashes, the Ca- and S-rich class C ashes, particularly these formed in circulating fluidised bed combustion (CFBC) boilers, are typically not considered as viable cementitious materials for blending with or substituting the OPC. We studied the physical, chemical-mineralogical characteristics of the mechanically activated Ca-rich CFBC fly ash pastes and mortars with high volume OPC substitution rates to find potential alternatives for OPC in building materials and composites. Our findings indicate that compressive strength of pastes and mortars made with partial to complete replacement of the mechanically activated CFBC ash to OPC is comparable to OPC concrete, showing compared to OPC pastes reduction in compressive strength only by <10% at 50% and <20% at 75% replacement rates. Our results show that mechanically activated Ca-rich CFBC fly ash can be successfully used as an alternative CSA-cement type binder.

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The Study of Hydration and Carbonation Reactions and Corresponding Changes in the Physical Properties of Co-Deposited Oil Shale Ash and Semicoke Wastes in a Small-Scale Field Experiment

Cited by 8 publications

References 15 publications

Evolution of Pore and Fracture Structure of Oil Shale under High Temperature and High Pressure

Evolution of Pore and Fracture Structure of Oil Shale under High Temperature and High Pressure

Geopolymeric Potential of the Estonian Oil Shale Solid Residues: Petroter Solid Heat Carrier Retorting Ash

Design of High Volume CFBC Fly Ash Based Calcium Sulphoaluminate Type Binder in Mixtures with Ordinary Portland Cement

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