gypie gold southlands BillyteaBeen down this pit a number of...

gypie gold southlands Billytea
Been down this pit a number of times. It is deep and therefore the stress and loads a larger.
The coal is fairly weak (but good quality)
The more this longwall retracts the thicker the sulfur bearing portion and 1% increase in sulfur drops the price considerably.
When a long wall is extracted it creates an abuttment of weight (or forces) thrown over onto to solid supported areas. There is always an abuttment force somewhere in the area of 10 to 100m in advance of mining (or extraction) this increas in force buts strain on the roof and pillars causing them to deteriorate, collaspse, or take weight and sag.
SL2 created the same forces and threw this weight on SL3
I think that southlands have a small set of manually operated chocks (to be replace SL4 with a set from Monee Colliery) This old set is inept for the purpose, they are slow and I believe must be operated some distance back from the shearer.
PUR is a two pack resin exspanding foam that flows into small fissures etc and sets to bind the broken roof etc together. Where the roof has fallen this may have to be packed and filled to form a "bridge" for the chocks to support the roof again.
I can not tell you anymore than what has been reported but I recently heared of chocks being metal bound but only from one source.