Page 104 - Advances In Productive, Safe, and Responsible Coal Mining

88 Advances in Productive, Safe, and Responsible Coal Mining

CWP and progressive, massive fibrosis (PMF) among coal miners over the past
15years where previously, these diseases had been nearly eradicated. They state that
the prevalence of PMF has reached levels not seen since the 1970s.
Dust control for continuous miner operations is chiefly accomplished by the face
ventilation system in conjunction with dust control water sprays installed on the cut-
ting drum as well as on the machine frame, and, in many cases, dust scrubber systems
that scrub and filter the exhaust air behind the cutting drum. Face ventilation should
preferably be exhausting so that fresh air enters the section and contaminated dust-
laden air exits the section behind the ventilation curtain or through exhaust tubing
and an auxiliary fan. It is important that the inlet end of the exhaust tube is maintained
within 3–5m (10 to 15ft) of the face to prevent short circuiting of fresh air causing
methane and dust accumulations in the face area.
Water sprays on the cutting drum as well as on the continuous miner frame capture
and bind respirable dust with larger water droplets that either drop out of the exhaust
air stream or can then be captured in a scrubber system. A scrubber system may be
used on the continuous miner in conjunction with a blowing auxiliary fan and tubing.
The blowing face fan has the advantage that facilitates fresh air reaching and sweeping
the face more effectively, while the dusty exhaust air is then cleaned by the scrubber
system.

6.5 Belt ventilation and dust control

Proper ventilation and dust control for conveyor belts and belt systems is equally
important as face ventilation. Conveyor belts are a frequent source of mine fires
and the belt fire at the Aracoma Alma mine in 2006 caused two fatalities. Following
this fire, the US Mine Safety and Health Administration (MSHA) formed the
“Technical Study Panel on the Utilization of Belt Air and the Composition and Fire
Retardant Properties of Belt Materials in Underground Coal Mining” that rec-
ommended, among other findings, the following[4]:
l If belt air is used to ventilate a working section, an atmospheric monitoring system (AMS)
must be utilized to monitor the air quality in the belt entry with CO and smoke sensors. This
is codified in 30 CFR §75.350–351.
3
l Respirable dust concentrations in belt conveyor entries should be kept below 1mg/m deter-
mined in an 8-h, time-weighted average.
Belt air flow away from the face is preferred because it permits the mine operator to
apply rock dust to belt entries while miners are working in the face area. Also, in the
event of a belt fire, smoke and fire gases travel toward the return rather than to
the face.
For belt dust control, belts should be equipped with water spray systems at the load-
ing and discharge points. Scrapers should be installed and maintained to keep the belt
clean and to reduce the formation of dust to a minimum. All belt runs must be fre-
quently inspected for proper alignment to avoid rubbing on the structure.