skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants

Abstract

The project proposal was approved for only the phase I period. The goal for this Phase I project was to develop an industrial model that can perform continuous and efficient dewatering of fine coal slurries of the previous flotation process to fine coal cake of {approx}15% water content from 50-70%. The feasibility of this model should be demonstrated experimentally using a lab scale setup. The Phase I project was originally for one year, from May 2005 to May 2006. With DOE approval, the project was extended to Dec. 2006 without additional cost from DOE to accomplish the work. Water has been used in mining for a number of purposes such as a carrier, washing liquid, dust-catching media, fire-retardation media, temperature-control media, and solvent. When coal is cleaned in wet-processing circuits, waste streams containing water, fine coal, and noncombustible particles (ash-forming minerals) are produced. In many coal preparation plants, the fine waste stream is fed into a series of selection processes where fine coal particles are recovered from the mixture to form diluted coal fine slurries. A dewatering process is then needed to reduce the water content to about 15%-20% so that the product is marketable. However, in the dewatering processmore » currently used in coal preparation plants, coal fines smaller than 45 micrometers are lost, and in many other plants, coal fines up to 100 micrometers are also wasted. These not-recovered coal fines are mixed with water and mineral particles of the similar particle size range and discharged to impoundment. The wasted water from coal preparation plants containing unrecoverable coal fine and mineral particles are called tailings. With time the amount of wastewater accumulates occupying vast land space while it appears as threat to the environment. This project developed a special extruder and demonstrated its application in solid-liquid separation of coal slurry, tailings containing coal fines mostly less than 50 micron. The extruder is special because all of its auger surface and the internal barrier surface are covered with the membranes allowing water to drain and solid particles retained. It is believed that there are four mechanisms working together in the dewatering process. They are hydrophilic diffusion flow, pressure flow, agitation and air purging. Hydrophilic diffusion flow is effective with hydrophilic membrane. Pressure flow is due to the difference of hydraulic pressure between the two sides of the membrane. Agitation is provided by the rotation of the auger. Purging is achieved with the air blow from the near bottom of the extruder, which is in vertical direction.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
West Virginia University Research
Sponsoring Org.:
USDOE
OSTI Identifier:
946468
DOE Contract Number:
FG26-05NT42498
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; COAL; COAL FINES; COAL PREPARATION PLANTS; DIFFUSION; FLOTATION; HYDRAULICS; MEMBRANES; MINING; MIXTURES; PARTICLE SIZE; ROTATION; SLURRIES; TAILINGS; TEMPERATURE CONTROL; WASHING; WASTES; WATER; WATER REMOVAL

Citation Formats

Wu Zhang, David Yang, Amar Amarnath, Iftikhar Huq, Scott O'Brien, and Jim Williams. Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants. United States: N. p., 2006. Web. doi:10.2172/946468.
Wu Zhang, David Yang, Amar Amarnath, Iftikhar Huq, Scott O'Brien, & Jim Williams. Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants. United States. doi:10.2172/946468.
Wu Zhang, David Yang, Amar Amarnath, Iftikhar Huq, Scott O'Brien, and Jim Williams. Fri . "Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants". United States. doi:10.2172/946468. https://www.osti.gov/servlets/purl/946468.
@article{osti_946468,
title = {Development of an Ultra-fine Coal Dewatering Technology and an Integrated Flotation-Dewatering System for Coal Preparation Plants},
author = {Wu Zhang and David Yang and Amar Amarnath and Iftikhar Huq and Scott O'Brien and Jim Williams},
abstractNote = {The project proposal was approved for only the phase I period. The goal for this Phase I project was to develop an industrial model that can perform continuous and efficient dewatering of fine coal slurries of the previous flotation process to fine coal cake of {approx}15% water content from 50-70%. The feasibility of this model should be demonstrated experimentally using a lab scale setup. The Phase I project was originally for one year, from May 2005 to May 2006. With DOE approval, the project was extended to Dec. 2006 without additional cost from DOE to accomplish the work. Water has been used in mining for a number of purposes such as a carrier, washing liquid, dust-catching media, fire-retardation media, temperature-control media, and solvent. When coal is cleaned in wet-processing circuits, waste streams containing water, fine coal, and noncombustible particles (ash-forming minerals) are produced. In many coal preparation plants, the fine waste stream is fed into a series of selection processes where fine coal particles are recovered from the mixture to form diluted coal fine slurries. A dewatering process is then needed to reduce the water content to about 15%-20% so that the product is marketable. However, in the dewatering process currently used in coal preparation plants, coal fines smaller than 45 micrometers are lost, and in many other plants, coal fines up to 100 micrometers are also wasted. These not-recovered coal fines are mixed with water and mineral particles of the similar particle size range and discharged to impoundment. The wasted water from coal preparation plants containing unrecoverable coal fine and mineral particles are called tailings. With time the amount of wastewater accumulates occupying vast land space while it appears as threat to the environment. This project developed a special extruder and demonstrated its application in solid-liquid separation of coal slurry, tailings containing coal fines mostly less than 50 micron. The extruder is special because all of its auger surface and the internal barrier surface are covered with the membranes allowing water to drain and solid particles retained. It is believed that there are four mechanisms working together in the dewatering process. They are hydrophilic diffusion flow, pressure flow, agitation and air purging. Hydrophilic diffusion flow is effective with hydrophilic membrane. Pressure flow is due to the difference of hydraulic pressure between the two sides of the membrane. Agitation is provided by the rotation of the auger. Purging is achieved with the air blow from the near bottom of the extruder, which is in vertical direction.},
doi = {10.2172/946468},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Dec 22 00:00:00 EST 2006},
month = {Fri Dec 22 00:00:00 EST 2006}
}

Technical Report:

Save / Share:
  • The Department of Energy (DOE) awarded a contract entitled Engineering Development of Advanced Physical Fine Coal Cleaning Technology -- Froth Flotation,'' to ICF Kaiser Engineers with the following team members, Ohio Coal Development Office, Babcock and Wilcox, Consolidation Coal Company, Eimco Process Equipment Company, Illinois State Geological Survey and Virginia Polytechnic Institute and State University. The overall project scope of the engineering development project is to conceptually develop a commercial flowsheet to maximize pyritic sulfur reduction at practical energy recovery values. This is being accomplished by utilizing the basic research data on the surface properties of coal, mineral matter andmore » pyrite obtained from the Coal Surface Control for Advanced Fine Coal Flotation Project, to develop this conceptual flowsheet. In addition to actual bench scale testing, other unit operations from other industries processing fine material will be reviewed for potential application and incorporated into the design if appropriate. This report describes progress on the unit operation design and process performance data required to (1) reduce or eliminate the technical and engineering uncertainties of the preliminary 20TPH advanced location semi-works plant and (2) design, build and operate a 2--3 TPH advanced flotation POC module; raw coal characterization; advanced flotation round robin; bench scale process testing; and component and unit operations development. 8 refs., 18 figs., 5 tabs.« less
  • This report describes the addition of a conventional froth flotation circuit into the FORTRAN coal cleaning module of the Integrated Environmental Control (IEC) model. The purpose of this modification is to include froth flotation as an option to clean the coal fines. The current model has three beneficiation: levels (2, 3, and 4) in which different streams are washed by specific gravity equipment. Level 2 washes only the coarse stream. Level 3 washes the coarse and medium streams. Level 4 washes the coarse, medium, and fine streams. This modification adds a fifth level, which uses specific gravity equipment to washmore » the coarse and medium streams and froth flotation equipment for the fine stream. The specific size fractions in each stream are specified by the model user. As before, the model optimizes the yield of each circuit in order to achieve a target coal quality for the cleaned coal product.« less
  • This report describes the addition of a conventional froth flotation circuit into the FORTRAN coal cleaning module of the Integrated Environmental Control (IEC) model. The purpose of this modification is to include froth flotation as an option to clean the coal fines. The current model has three beneficiation: levels (2, 3, and 4) in which different streams are washed by specific gravity equipment. Level 2 washes only the coarse stream. Level 3 washes the coarse and medium streams. Level 4 washes the coarse, medium, and fine streams. This modification adds a fifth level, which uses specific gravity equipment to washmore » the coarse and medium streams and froth flotation equipment for the fine stream. The specific size fractions in each stream are specified by the model user. As before, the model optimizes the yield of each circuit in order to achieve a target coal quality for the cleaned coal product.« less
  • The Bureau of Mines is investigating a dewatering technique for coal-clay waste that uses a flocculant, polyethylene oxide (PEO). This flocculant forms strong stable flocs that can be dewatered on a static screen. A field test unit (FTU) using this technique was operated at approximately 400 gal/min, using a waste stream from the flotation circuit of a coal preparation plant.
  • Battelle, in cooperation with the Electric Power Research Institute (EPRI) CQ, Inc., Ashbrook-Simon-Hartley (ASH), and Professor S. H. Chiang of the University of Pittsburgh, is developing an advanced process for the dewatering of fine and ultrafine coals. The advanced process, called Electroacoustic Dewatering (EAD), capitalizes on the adaptation of synergistic effects of electric and acoustic fields to commercial coal dewatering systems, such as belt filter presses. The project has the following objectives: To validate the expected technical feasibility and energy conservation/economic benefits of the EAD process as applied to fine ({minus}100 mesh) and ultrafine ({minus}325 mesh) coal; and to obtainmore » data from a continuous, process research unit (PRU) in order to conduct a reliable economic analysis and to design commercial EAD filters as well as to promote adaptation of the process by the coal preparation industry. Progress is reported. 2 figs., 4 tabs.« less