Project leader Robert Timko said concerns had been raised that, during remote operation of a continuous miner, the face was not receiving sufficient air and the operator could be subjected to elevated levels of methane and respirable coal mine dust.

In an extended cut the remote operator is usually located 30 to 50 feet behind the continuous miner.

“We are looking at airflow around the face as we are concerned about methane emissions as well as dust generated at the face,” Timko said.

The main problems researchers faced in operating mines were logistic. The distance from the exhaust end of the ventilation duct to the face varied.

The inability to measure airflow, methane emissions and dust generated at the face prompted researchers to explore alternative ways to examine these variables. To solve this the research team conducted tests in a full scale continuous miner ventilation gallery.

Preliminary data on two different entry widths using a simulated initial cut and box cut showed some interesting air velocity and methane concentrations, and an unusual airflow the researchers were not expecting.

“When you look at the results while using a ventilation curtain in a 13 1/2 foot wide box cut, it looks like there is an eddy occurring at the face. In plan view it looks like there is a counterclockwise eddy that forms at the face and continues to swirl at the face. Looking down on the simulation the ventilation takes on the appearance of a figure-8,” he said.

“Logically, you would think that the jet of air coming from the left-side curtain would stay attached to the rib, go to the face, flow across the face and come back down the right rib.

“What appears to be happening is that, immediately after leaving the curtain, the air becomes detached from the rib, takes a right turn and goes at almost right angles across from the entry 20 to 25 feet from the face, makes a left turn and heads up the right side of the face. This only occurs in the narrower box cut.

“In the 16 foot wide slab cut the air jet behaves as one would expect; proceeding down the left rib, across the face and out the right rib.”

The ventilation team is working on the airflow behaviour to determine why this would occur. Airflow data will provide flow profiles to compare face ventilation effectiveness for a variety of face operating conditions including entry geometry and mining equipment configuration near the face.

The delivery and distribution of intake air at the face is critical for achieving adequate methane and dust control.