Low Temperature Drying of Ultrafine Coal

A new dewatering technology, called low temperature drying, has been developed to remove water from ultrafine (minus 325 mesh) coal particles. The process subjects partially dewatered solids to intense mechanical shearing in the presence of unsaturated air. Theoretical analysis of the thermodynamic properties of water indicates residual surface moisture should spontaneously evaporate under these conditions. This is contingent on the large surface area of these fine particles being adequately exposed to an unsaturated stream of air. To demonstrate this process, three dispersion methods were selected for bench-scale testing; the static breaker, air jet conveyor, and centrifugal fan. Each of these devices was chosen for its ability to fully disperse and pneumatically convey the feed cake. The moisture content of the feed cake, and the temperature and relative humidity of the process air were the key parameters that most significantly affected dryer performance. Of the three methods tested, the centrifugal fan produced the best results. The fan was capable of handling feeds as wet as 21.5% and consistently dried the coal fines below 2% moisture. The cost of the air and heat required to provide good drying performance was modeled to explore the practicality of the drying process. Modeling was accomplished by modifying equations developed for thermal dryers. The modeling results indicate, if good exposure of the fine particle surface area is achieved, dryers operating with either heated or unheated (ambient) air can be used for drying ultrafine coal.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Mining and Minerals Engineering

Department dc:contributor.department

Mining and Minerals Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2010

Author dc:creator

• Freeland, Chad Lee

Chairs dc:contributor.committeechair

• Yoon, Roe-Hoan
• Luttrell, Gerald H.

Committee member dc:contributor.committeemember

• Adel, Gregory T.

• ultrafine coal
• coal dewatering
• low temperature drying

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Dc Identifier Other

etd-01072011-170711

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/76750