12 Matching Results

Search Results

Advanced search parameters have been applied.
in publisher: "Virginia Polytechnic Institute and State University. Digital Library and Archives."  
Results: 1 - 12
open access

Control of pyrite surface chemistry in physical coal cleaning

Description: The successful separation of pyrite from coal by flotation is dependent to a large extent upon the selectivity of the process, and the use of a pyrite depressant is one of the most important and cost-effective techniques for achieving this. This report evaluates the effects of three factors on the floatability of pyrite. These are (1) the superficial oxidation of pyrite, (2) the contamination of pyrite surfaces by carbonaceous matter, and (3) pulp redox potentials. XPS (x-ray photoelectron spec… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H. & Ou, Z. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning

Description: To better understand the surface chemical properties of coal and mineral pyrite, studies on the effect of flotation surfactants (frother and kerosene) on the degree of hydrophobicity have been conducted. The presence of either frother or kerosene enhanced the flotability of coal and mineral pyrite with a corresponding decrease in induction time over the pH range examined. Scanning electron microscopy (SEM) results indicate a correlation exists between the sample surface morphology and crystal s… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H.; Zachwieja, J. & Lagno, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning

Description: One of the most difficult separations in minerals processing involves the differential flotation of pyrite and coal. Under practical flotation conditions, they are both hydrophobic and no cost-effective method has been developed to efficiently reject the pyrite. The problem arises from inherent floatability of coal and pyrite. Coal is naturally hydrophobic and remains so under practical flotation. Although pyrite is believed to be naturally hydrophilic under practical flotation conditions it un… more
Date: June 24, 1992
Creator: Yoon, R. H. & Richardson, P. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning. Seventh quarterly progress report, March 1, 1991--May 31, 1991

Description: The removal of pyrite from coal by flotation or any other surface chemistry based separation process is often hampered by the apparent hydrophobicity of the mineral. Results obtained in this project suggest that corrosion processes are responsible for the apparent hydrophobicity of pyrite in aqueous environments. Characterization of the corrosion products of pyrite in acidic and alkaline solution has been performed using electrochemical (cyclic voltammetry and single-potential-step chronoampero… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H. & Zachwieja, J. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning. Tenth quarterly progress report, December 1, 1991--February 29, 1992

Description: One of the most difficult separations in minerals processing involves the differential flotation of pyrite and coal. Under practical flotation conditions, they are both hydrophobic and no cost-effective method has been developed to efficiently reject the pyrite. The problem arises from inherent floatability of coal and pyrite. Coal is naturally hydrophobic and remains so under practical flotation. Although pyrite is believed to be naturally hydrophilic under practical flotation conditions it un… more
Date: June 24, 1992
Creator: Yoon, R. H. & Richardson, P. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning. Second quarterly progress report, December 1, 1989--February 28, 1990

Description: To better understand the surface chemical properties of coal and mineral pyrite, studies on the effect of flotation surfactants (frother and kerosene) on the degree of hydrophobicity have been conducted. The presence of either frother or kerosene enhanced the flotability of coal and mineral pyrite with a corresponding decrease in induction time over the pH range examined. Scanning electron microscopy (SEM) results indicate a correlation exists between the sample surface morphology and crystal s… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H.; Zachwieja, J. & Lagno, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning. Fifth quarterly progress report, September 1, 1990--November 30, 1990

Description: The successful separation of pyrite from coal by flotation is dependent to a large extent upon the selectivity of the process, and the use of a pyrite depressant is one of the most important and cost-effective techniques for achieving this. This report evaluates the effects of three factors on the floatability of pyrite. These are (1) the superficial oxidation of pyrite, (2) the contamination of pyrite surfaces by carbonaceous matter, and (3) pulp redox potentials. XPS (x-ray photoelectron spec… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H. & Ou, Z. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning. Third quarterly progress report, March 1, 1990--May 31, 1990

Description: Correlation of the hydrophobicity measurements of coal and mineral pyrite with changes in the surface composition of the samples as determined by x-ray photoelectron spectroscopy (XPS) reveals that similar surface oxidation products are found on both mineral and coal pyrite samples. The surface oxidation layer of these samples is comprised of different amounts of hydrophilic species (iron hydroxy-oxides and/or iron oxides) and hydrophobic species (polysulfide or elemental sulfur). The resulting… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H.; Zachwieja, J. B. & Lagno, M. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

24-Channel Geophone Array for Horizontal or Vertical Boreholes: Final Report

Description: Improved ground-imaging capabilities have enormous potential to increase energy, environmental, and economic benefits by improving exploration accuracy and reducing energy consumption during the mining cycle. Seismic tomography has been used successfully to monitor and evaluate geologic conditions ahead of a mining face. A primary limitation to existing seismic tomography, however, is the placement of sensors. The goal of this project is to develop an array of 24 seismic sensors capable of bein… more
Date: October 24, 2003
Creator: Westman, Erik C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning

Description: Correlation of the hydrophobicity measurements of coal and mineral pyrite with changes in the surface composition of the samples as determined by x-ray photoelectron spectroscopy (XPS) reveals that similar surface oxidation products are found on both mineral and coal pyrite samples. The surface oxidation layer of these samples is comprised of different amounts of hydrophilic species (iron hydroxy-oxides and/or iron oxides) and hydrophobic species (polysulfide or elemental sulfur). The resulting… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H.; Zachwieja, J. B. & Lagno, M. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Control of pyrite surface chemistry in physical coal cleaning

Description: The removal of pyrite from coal by flotation or any other surface chemistry based separation process is often hampered by the apparent hydrophobicity of the mineral. Results obtained in this project suggest that corrosion processes are responsible for the apparent hydrophobicity of pyrite in aqueous environments. Characterization of the corrosion products of pyrite in acidic and alkaline solution has been performed using electrochemical (cyclic voltammetry and single-potential-step chronoampero… more
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H. & Zachwieja, J. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Development of a video-based slurry sensor for on-line ash analysis. Second quarterly technical progress report, January 1, 1995--March 31, 1995

Description: Automatic control of fine coal cleaning circuits has traditionally been limited by the lack of sensors for on-line ash analysis. Although several nuclear-based analyzers are available, none have seen widespread acceptance. This is largely due to the fact that nuclear sensors are expensive and tend to be influenced by changes in seam type and pyrite content. Recently, researchers at VPI&SU have developed an optical sensor for phosphate analysis. The sensor uses image processing technology to ana… more
Date: April 24, 1995
Creator: Adel, G. T. & Luttrell, G. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen