
Click Picture for Enlargement
October 3 through October 16, 1999
Rising carbon
monoxide levels in the gob were a major focus as the period began. Carbon
dioxide inert gas injection was continued, and carbon dioxide chambers
were constructed at each of the underground seals to reduce leakage of
intake air into the isolated area.. As carbon monoxide levels stabilized
in the gob, reventilation of the longwall face continued. Carbon dioxide
injection was causing levels of CO2 on the face to reach levels as high as
13 percent. Injection rates were reduced from 1250 cfm to 1000 cfm, and
finally on October 7 reduced to 700 cfm. Levels of CO2 on the face
continued to be elevated, with concentrations as high as 2.52 percent
found on October 10. Plans were developed to replace part of the CO2
injection with nitrogen injection on October 12. Initial rates of nitrogen
injection were 500 cfm, with continuing carbon dioxide injection at 400
cfm. The rate was changed later in the day to increase nitrogen injection
up to 800 cfm with carbon dioxide injection remaining at 400 cfm. |