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Title: Characterization of multiphase fluid flow during air-sparged hydrocyclone flotation by X-ray CT. Thirteenth quarterly report: 14 August--13 November, 1993

Abstract

The research activities during this quarter of the DOE project, {open_quotes}Characterization of Multiphase Fluid Flow During Air-Sparged Hydrocyclone Flotation{close_quotes}, involved a detailed parametric study of the flotation response of the ASH, establishing an empirical correlation between flotation response and operating variables, and development of a phenomenological description of the observed responses. In these experiments with quartz particles, flotation response is essentially characterized by recovery of the solids to the overflow. Dimensionless variables such as the ratio of overflow opening area to underflow opening area, the ratio of air flow rate to slurry flow rate, percent solids in the feed suspension, particle size, inlet velocity (i.e. slurry pressure) are all of paramount importance. A series of experiments were designed to systematically study the effects of these variables on the flotation response. The radial density distribution profiles obtained from x-ray CT measurements (presented in earlier quarterly reports) reflect the fluid flow behavior of the ASH to a great extent. Based on the results of the experimental tests an empirical model has been developed correlating recovery with the operating variables.

Authors:
Publication Date:
Research Org.:
Utah Univ., Salt Lake City, UT (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10118040
Report Number(s):
DOE/PC/90311-13
ON: DE94005758; TRN: 94:001592
DOE Contract Number:
FG22-90PC90311
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 16 Nov 1993
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 01 COAL, LIGNITE, AND PEAT; SLURRIES; FLUID FLOW; QUARTZ; FLOTATION; PROGRESS REPORT; FLOW MODELS; COMPUTERIZED TOMOGRAPHY; SOLIDS FLOW; LIQUID FLOW; FLUID MECHANICS; X RADIATION; WATER; SPARGERS; AIR FLOW; CYCLONE SEPARATORS; PARAMETRIC ANALYSIS; 420400; 013000; HEAT TRANSFER AND FLUID FLOW; TRANSPORT, HANDLING, AND STORAGE

Citation Formats

Miller, J.D. Characterization of multiphase fluid flow during air-sparged hydrocyclone flotation by X-ray CT. Thirteenth quarterly report: 14 August--13 November, 1993. United States: N. p., 1993. Web. doi:10.2172/10118040.
Miller, J.D. Characterization of multiphase fluid flow during air-sparged hydrocyclone flotation by X-ray CT. Thirteenth quarterly report: 14 August--13 November, 1993. United States. doi:10.2172/10118040.
Miller, J.D. 1993. "Characterization of multiphase fluid flow during air-sparged hydrocyclone flotation by X-ray CT. Thirteenth quarterly report: 14 August--13 November, 1993". United States. doi:10.2172/10118040. https://www.osti.gov/servlets/purl/10118040.
@article{osti_10118040,
title = {Characterization of multiphase fluid flow during air-sparged hydrocyclone flotation by X-ray CT. Thirteenth quarterly report: 14 August--13 November, 1993},
author = {Miller, J.D.},
abstractNote = {The research activities during this quarter of the DOE project, {open_quotes}Characterization of Multiphase Fluid Flow During Air-Sparged Hydrocyclone Flotation{close_quotes}, involved a detailed parametric study of the flotation response of the ASH, establishing an empirical correlation between flotation response and operating variables, and development of a phenomenological description of the observed responses. In these experiments with quartz particles, flotation response is essentially characterized by recovery of the solids to the overflow. Dimensionless variables such as the ratio of overflow opening area to underflow opening area, the ratio of air flow rate to slurry flow rate, percent solids in the feed suspension, particle size, inlet velocity (i.e. slurry pressure) are all of paramount importance. A series of experiments were designed to systematically study the effects of these variables on the flotation response. The radial density distribution profiles obtained from x-ray CT measurements (presented in earlier quarterly reports) reflect the fluid flow behavior of the ASH to a great extent. Based on the results of the experimental tests an empirical model has been developed correlating recovery with the operating variables.},
doi = {10.2172/10118040},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1993,
month =
}

Technical Report:

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  • During this quarter a new set of experiments was carried out with and without collector in order to understand the flow patterns inside the ASH unit for both hydrophilic and hydrophobic particles. These tests were designed to study the effects of percent solids in the feed, A* - the nondimensional ratio of overflow opening area to underflow opening area, and the effect of collector addition on the flow characteristics. These experiments were done with 0%, 5% and 15% solids in the feed. The latter two cases were studied for three different A* values and also with and without the additionmore » of collector. The value of Q*, the dimensionless ratio of air f low rate and slurry flow rate was maintained at the same level (Q* 4.55). Quartz particles of size {minus}100 +200 mesh were used for this study rather than coal particles because they did not abrade and were of a higher density. The reagents and their dosages used were 40 ppm (water basis) of frother (MIBC) and 800 g of collector (dodecyl amine) per ton of solids in the suspension. At room temperature, quartz is intrinsically hydrophilic while addition of the amine collector renders the quartz particles hydrophobic. The absence of collector will be referred to as the hydrophilic case and the presence of collector will be referred to as the hydrophobic case.A total of 11 scans was taken over the entire length of the ASH unit. Software has now been developed to analyze the CT images obtained from these tests and is able to account for any offset of the air core from the axis of the ASH. In this way, the image is reconstructed and a radial density profile of the time averaged flow is generated. Some experimental results are presented graphically in Figures 1 through 4 at 0% and 5% solids in the suspension for both hydrophilic and hydrophobic cases.« less
  • During this quarter of the DOE project, ``Characterization of Multiphase Fluid Flow During Air-Sparged Hydrocyclone Flotation``, efforts were made to correlate the x-ray CT measurements with the flotation experiments reported in the last. quarterly report. In this regard the axial view of the flow regimes in the ASH during steady state operation were constructed from the radial density profiles as revealed by x-ray CT measurements. By studying the characteristics of the flow regimes from these axial views and relating them with flotation recovery data, a more detailed understanding of ASH flotation was possible. Construction of the axial view of themore » flow regimes and the effect of two operating variables, dimensionless area ratio (A* = overflow opening area/underflow opening area) and percent solids in the feed, are reported in this quarterly report.« less
  • During this quarter some experiments from the previous set were repeated to check the reproducibility of the results. Also, a new set of experiments was carried out to study the effects of (1) collector dosage, (2) Q* -- the nondimensional ratio of air flow rate to slurry flow rate, and (3) slurry pressure on the flow characteristics. Four different Q* values with hydrophobic particles in the feed slurry were studied. The value of A*, the dimensionless ratio of overflow opening area to underflow opening area, was maintained at the same level (A* 1.00). Quartz particles of size {sup {minus}}100 {supmore » +}200 mesh were used for this study rather than coal particles because they did not abrade and were of a higher density. The reagents used were 40 ppM (water basis) of MIBC frother and 800 g of dodecyl amine collector per ton of dry solids in the suspension. In other experiments with no solids in the feed suspension, collector level in the water was varied at 0, 10 and 20 ppM. At room temperature, quartz is intrinsically hydrophilic while addition of the amine collector renders the quartz particles hydrophobic. The absence of collector will be referred to as the hydrophilic case and the presence of collector will be referred to as the hydrophobic case.« less
  • The effect of A* (the dimensionless ratio of overflow opening area to underflow opening area) on the fluid flow behavior of the 2 inch ASH-2C unit was studied for different percentage of solids in the suspension. Limestone, a hydrophilic solid was chosen for study. The particle size of the solids was taken as {minus}100 {plus}200 mesh. Three different concentrations of solids in the suspension were considered, 5, 10 and 20% by weight. The corresponding pulp densities of the feed suspension for these three cases are 1.09, 1.18 and 1.36 g/cc respectively. Since no collector was added to the suspension, allmore » the solids are expected to report to the underflow. For all these studies the Q* value was maintained at the same level (Q* = 2.28). Reconstructed images from the CT scanner were analyzed using the graphics software developed at the University of Utah. Assuming the air core to be cylindrical in shape and using the previously generated calibration curve, the average density of the swirl layer and its average thickness were estimated for each slice. These results are presented graphically in the accompanying figures along the axis of the ASH unit from bottom to top.« less
  • The axial flow reversal was studied using tracer injection and results correlation with x-ray CT and flotation. Effects of dimensionless area ratio and flow rate ratio, percent solids in feed, and inlet pressure on location of surface of zero axial velocity in the ASH were studied. 4 figs.