The fundamental concept of bord and pillar methods of mining is that the coal seam is divided into a regular block like array by driving through it primary headings which are intersected at regular intervals by connecting cutthroughs. The headings and cutthroughs may be taken as “bords” although this is not strictly correct terminology. The blocks of coal bounded by them are the “pillars”. The pillars support the overlying strata during the “first workings” as the bords are driven. They may or may not be extracted systematically on subsequent “second workings”, depending on the scheme adopted. In its simplest and most traditional form bord and pillar workings are illustrated to the right.
Layouts such as the one displayed here originated from hand working practices in seams thicker than 1 m where insufficient waste material was obtainable during the working to allow construction of the packwalls and stowage necessary in hand worked longwall methods. Essentially it has always been the method of mining the medium-thick seams in Australia.
Exactly the same layout is suited to modern mechanised practices but it has taken some intervening stages of machine development to reach this situation.