Shortwall Underground Coal Mining

This method of mining was developed in the late 1960's to take advantage of the then recent development of suitable hydraulic longwall supports, coupled with the productivity and low capital cost of continuous miners and shuttle cars. In effect it gained some of the advantages of longwall mining without the cost of installing a complete set of longwall equipment
An installation roadway was driven as for a normal longwall, but only supports were installed. A continuous miner was then utilised to cut 3.5m wide open ended lifts off the face, with shuttle cars being used to transport coal along and off the face to the maingate belt in lieu of an AFC.
The face length was therefore limited by the length of shuttle car cables then available, but in practice most shortwall faces were considerably shorter than this (<90m).
Supports were connected to a reference rail which was then utilized to pull the 2 or 3 leg supports forward, in a similar manner to the use of an AFC to advance longwall supports.
Shortwall faces could be installed between two gate roads as for a longwall face, but in some cases were mined to a blind end and ventilated by auxiliary fan (not very suitable for gassy seams as the fans could draw from the goaf).
Shortwalls were used in an endeavour to increase the productivity of continuous miners at relatively low capital cost, sometimes as a transition stage while changing a mine to full longwall. In some cases, because they were somewhat more flexible, shortwalls were used to obtain the benefits of longwalls in mines, or parts of mines, where seam discontinuities or mine geometry made the use of full longwalls impractical
The main disadvantages of shortwalls compared to longwalls are:

• The width of the unsupported roof ahead of the chocks is governed by the width of a continuous miner as opposed to a shearer drum.
  
• Personnel have to work adjacent to the face which presents safety issues unless rib support is installed which would greatly slow production.
  
• The use of shuttle cars is by its nature not continuous and brings in all the disadvantages of trailing cables in the face area.

Shortwalls had only mixed success and there have been no shortwall operations in Australia (or elsewhere to the knowledge of the writer) for many years.