Yield stresses and sedimentation in dense flyash slurries

Stanmore, B. R.; Page, David

doi:10.1016/0032-5910(92)88023-b

Cited by 9 publications

(4 citation statements)

References 11 publications

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“…Coal fly ash is a coal combustion byproduct, which can be used alone or as an admixture in tailings managements due to its cementitious and alkaline nature [8][9][10][11][12][13][14]. Stanmore and Page [15] measured the yield stress of dense fly ash slurries by a vane technique and stated that the yield stress increased with time owing to the pozzolanic reaction of precipitated calcite. Mahlaba [16] studied the yield stress of saline fly ash paste and noted that the higher salinity in fly ash pastes becomes less flowable paste.…”

Section: Background Theorymentioning

confidence: 99%

“…Stanmore and Page [15] measured the yield stress of dense fly ash slurries by a vane technique and stated that the yield stress increased with time owing to the pozzolanic reaction of precipitated calcite. Mahlaba [16] studied the yield stress of saline fly ash paste and noted that the higher salinity in fly ash pastes becomes less flowable paste.…”

Section: Introductionmentioning

confidence: 99%

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Rheology of Fly Ash Mixed Tailings Slurries and Applicability of Prediction Models

Lee

Kim

2017

Minerals

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Abstract:Coal fly ash has potential applications in the management of reactive mine tailings. The shear stress versus shear rate curves obtained during viscometer tests are presented to describe the rheological behaviors of tailings slurries mixed with fly ash. The investigation was conducted on specimens prepared with different fly ash additions as well as prepared at variable conditions of temperature, mixing time, and CaCl 2 solution. It was observed that the rheological properties of ash-tailings slurry mixtures are influenced by the hydration of fly ash as well as the particle packing and arrangement. Rheological properties of specimen mixtures were determined from the resulting flow curves using the existing rheological models. The performance of prediction models in calculating the rheological properties of the mixed specimens, as quantified by the root mean square error (RMSE), varied with the mixture constituents, temperature, and time. In general, the Papanastasion, Herschel-Bulkley, Sisko, and Robertson-Stiff models were found to be favorable for use with mixtures of fly ash and tailings slurries, compared to the Bingham, Modified Bingham, Casson, and De Kee models.

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Section: Background Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rheology of Fly Ash Mixed Tailings Slurries and Applicability of Prediction Models

Lee

Kim

2017

Minerals

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“…Dense slurries are generally characterised by the volume fraction of the solid in suspension. The literature indicates [20,21] that a 50% volume fraction mixture is about the maximum possible loading which will give a mobile slurry able to be pumped by a standard high pressure pump. Unfortunately biomass such as 'grassy' wheat straw retains the plant cell structure, which involves the cellulosic cell walls surrounding what is effectively a void space where the cytoplasm has consolidated by drying after ripening.…”

Section: Dense Slurriesmentioning

confidence: 99%

Can biomass be satisfactorily gasified under pressure using an aqueous slurry feed? Examination by simulation

Stanmore¹,

Nzihou²

2017

Biomass and Bioenergy

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A major hurdle for the gasification of biomass under pressure is the need to introduce a fibrous biomass feed material such as straw, switchgrass or miscanthus into a pressure vessel. One proposed solution is to prepare a dense aqueous slurry from the biomass and then use a conventional high pressure pump. The production of syngas from wheat straw and subsequent power generation is examined theoretically in an Australian context. A slurry of concentration of 50% biomass by volume, which is regarded as the maximum pumpable value, is dried with superheated steam and the biomass gasified at 2 MPa with steam only in cyclones. It was found that the thermal deficiency of introducing excessive liquid water is considerable, rendering the process unsustainable. The problem can be overcome by employing a subsidiary fuel such as natural gas, but even with the minimal amount of water, the required energy input is equivalent to that of the straw. The net electrical efficiency of the process based on both fuels is 33.5%, so that the approach would be contemplated only if the over-riding consideration was the use of the straw for energy generation. The zero net present value cost of power production is 125 $ MWh-1 for 90 Gg of straw consumption per annum.

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“…with saturated ammonium chloride solution (Stanmore & Page, 1992). The resulting medium was analyzed for calcium by atomic absorption spectroscopy.…”

Section: Comparing the Concentration Of Calcium Hydroxide 183mentioning

confidence: 99%

Comparing the Concentration of Calcium Hydroxide in the Diffuse Double Layer by Modeling and Experiment

Pullammanappallil

Iyer

Stanmore

et al. 2005

Particulate Science and Technology

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The leaching of elements from the surface of charged fly ash particles is known to be an unsteady process. The mass transfer resistance provided by the diffuse double layer has been quantified as one of the reasons for this delayed leaching. In this work, a model based on mass transfer principles for predicting the concentration of calcium hydroxide in the diffuse double layer is presented. The significant difference between predicted calcium hydroxide concentration and the experimentally measured is explained.

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Yield stresses and sedimentation in dense flyash slurries

Cited by 9 publications

References 11 publications

Rheology of Fly Ash Mixed Tailings Slurries and Applicability of Prediction Models

Rheology of Fly Ash Mixed Tailings Slurries and Applicability of Prediction Models

Can biomass be satisfactorily gasified under pressure using an aqueous slurry feed? Examination by simulation

Comparing the Concentration of Calcium Hydroxide in the Diffuse Double Layer by Modeling and Experiment

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