An Investigation of Longwall Gob Gas Behavior and Control Methods

The National Institute for Occupational Safety and Health (NIOSH) has initiated the use of a tracer gas in field studies to characterize geologic and mining factors influencing the migration of longwall gob gas. Three studies have been conducted using sulfur hexafluoride (SF6) at a coal mine in the Northern Appalachian Basin operating in the Pittsburgh Coalbed. Eight underground tracer gas releases and one gob gas venthole release are summarized. The results indicate that the gas flow in the bleeder network and in the interior regions of longwall panel gobs do not strongly interact and that the negative pressure provided by gob gas venthole exhausters is very significant in maintaining this behavior. The data also show that ventilation practices employed in a large multi-panel gob area are functioning in accordance with the intent of the engineering design, a fact which would be difficult to evaluate using conventional mine ventilation measurement methods

Methane emissions and airflow patterns along longwall faces and through bleeder ventilation systems

The Gros-Horloge, built next to the town belfry; Rouen is the former center of the Rotomagi; invaded by Normans in the 9th century; occupied by England 1418-1449. It is the site of trial and execution of Joan of Arc in 1431; taken by Huguenots 1562; held by Germany 1870; site of famous 13th-century Gothic cathedral damaged in World War II. Source: Thesaurus of Geographic Names (Notes) [website]; http://www.getty.edu/research/conducting_research/vocabularies/tgn/ (accessed 7/16/2008

Control of longwall gob gas with cross-measure boreholes (upper Kittanning coalbed) /

Bibliography: p. 17.Mode of access: Internet