Browsing by Author "Kiser, Michael James"

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    Development of Methods to Aid in Flotation Circuit Evaluations and Drip Pan Design
    Kiser, Michael James (Virginia Tech, 2012-03-28)
    Field assessments were performed to establish the performance capabilities of a new flotation technology for fine coal upgrading, known as StackCell flotation. Flotation release analysis was performed on all samples to determine the amount of hydrophilic material present in the streams around the flotation cell. Data from this work supported recommendations from the equipment manufacturer that the wash water distribution system should be changed to a drip pan and that the design of the slurry-air distributor from the mixing chamber should be altered. The experimental data showed that as froth depth, rotor speed, and wash water rate changed, the performance of the cell followed expected trends with respect to product quality, but diverged from expected trends with respect to carbon recovery and yield. Other work performed includes the development of a new carbon partitioning test, which uses a blender to provide a high shear environment and uses oil to partition the slurry into a carbon rich oil phase and an ash rich pulp phase. This test is capable of producing results comparable to those of a traditional release analysis. Lastly, a spreadsheet program was developed that can aid users in designing drip pans. This program is capable of producing custom designs or unit cell designs. A study of the effect that plate thickness has on flow rate was performed in order to develop a model for flow through an orifice plate. The results of this work showed that plate thickness has little to no effect on the flow rate.
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    New Methodologies for the Characterization and Separation of Rare Earth Elements Present in Coal
    Kiser, Michael James (Virginia Tech, 2015-11-24)
    Three phases of work were performed for this study. First a new form of liberation analysis was created and applied to two coal samples from separate formations. This new method of liberation analysis attempts to remove sources of error found in the traditional form of liberation analysis. This new method is capable of producing results comparable to multiple iterations of the traditional liberation analysis while using only one head sample. The new method relies on the mathematical reconstruction of the data to produce the resulting liberation profile. This allows the user to easily expand the method to include more liberation profiles without greatly increasing the amount of head weight needed. The results of this phase confirm that the products of each liberation profile reconstitute the correct feed ash. The second phase of work focused on the evaluation and concentration of rare earth elements (REEs) present in the refuse streams of coal processing plants found in the eastern United States. Twenty plants were sampled for the fleet study. Samples of these plants' refuse streams were collected and their REE and ash contents were determined. Coal from the Eagle seam, Fire Clay seam, and Fire Clay Rider were collected and tested during the concentration phase. Samples of a waste coal from the Pittsburgh seam and a coal combustion by prodcut were also provided by a third party. The separation methods investigated include multi-gravity separation, electrostatic separation, and selective oil agglomeration. Partition curves from x-ray sorting devices were also applied to REE float-sink data as well. The results of this work show that REEs tend to partition with low ash material when viewing the results on an ash basis. Finally, the third phase of this work involved the application of x-ray sorting technology on different coals. This work showed that the x-ray sorting technology in question is capable of effectively treating prescreened feed with a size range of 2" x 1/4". The work also shows that the x-ray sorting technology also has applications in the power generation field, where it can be used to eliminate elements of environmental concern.