Drum manufacturer Krummenauer already supplies to Europe, Russia, Poland, Romania, Ukraine , South Africa and China and is presently establishing itself in Australia with its globoid drum and EB-water spray system.

The drum was designed to overcome high water and power usage, tool wear, dust, downtime, noise and the hazard of methane ignition, which becomes especially prevalent when a shearer is working in a seam with a dip, encounters rock bands or rock intrusions, or when siliceous or abrasive rock must be cut in the roof or floor.

“The durability of the conventional cylindrical drum is important to keep the cost and the time of repairs down,” said Krummenauer mining consultant Albert Dawood.

“The water spray system to reduce dust and the risks of mine gas explosions is compulsory but often not very advanced.

“Therefore the change for the mining machine’s cutting head today is overdue and requires a continuous and smooth loading, long durability and safety features to minimise hazards to life and equipment.”

Krummenauer undertook a comparison between its globoid drum with the EB-water spray system and a conventional cylindrical drum at the Reden colliery in Germany.

On a conventional cylindrical drum spiral vanes are set at 90 degrees to the axis of the drum and form a straight line in the layout lacing pattern.

The depth and the spacing distance between the vanes remain constant from the coalface to the discharge side of the drum. This means the cross-sections along the axis of the cylindrical drum also remain the same.

“During the cutting operations, the coal collects in the interstices and is transported towards the armoured face conveyor by the vane sides,” said Dawood.

“As the quantity of the mined product increases at the drum discharge side, the clearance space between the vanes is often not sufficient, so that product build-up occurs, and this congestion reduces the haulage speed and loading capacity of the shearer drum.

“Larger product may also become wedged between the vertical vanes and so obstruct loading out of the debris.”

Dawood said Krummenauer’s research and development had led to the patented Globoid shearer drum and the EB-water spray system where drums are customised to suit different mines’ structural conditions. The cutting track is also calculated with computer programs to optimise cutting parameters.

The vanes’ pitch rises progressively towards the drum discharge side. Intervals between the vanes have half-elliptical cross-sections towards the AFC and half-circular shapes towards the face side of the drum.

“All these changes in the drum make clearance volume permanently larger towards the discharge side and this can prevent coal build-up, blocking of coal and rock lumps,” Dawood said.

“Also the mobility of product between the vanes is improved, friction reduced and its disposal accelerated.”

Research by German coal company Deutsche Steinkohle showed fine coal reduction with the drums of almost 20%. Dawood said the globoid drum also benefited micron-size fines.

On the drum, the EB-water nozzles spray 1.05 litres per minute per nozzle and require pressure of 20 bar (290psi).

“The patented EB-water spray system actively absorbs dust by creating depression with its sophisticated water nozzle system,” Dawood said.

“Using a spray instead of a beam creates a larger area of protection from mine gas explosions.”