Transition at the coal face (continued)

To overcome the critical shortage of the war years (1939-1945) and immediately thereafter, the Joint Coal Board from its inception in NSW in 1947 set out to accelerate the introduction of mechanisation in underground mines and also the development of open-cut operations despite the fact that a ban by unions on the mechanical extraction of pillars was still in force.

To mine an underground seam of coal the procedure is to divide the virgin seam up into blocks (pillars) by driving headings (main development) and bords and cut throughs (secondary development) so that in plan the perception is akin to the geometry of a modern city, the development entries represented by the streets and the city blocks remaining by the pillars, which in a coal mine represent from 50 per cent to say 70 per cent of the virgin coal.

This account explains why proprietors were loth to invest in equipment which could at best only mine 50 per cent of the in situ coal. The reasons for this ban by the Miners Federation were mainly on the perceived safety issue arid no doubt also because pillar extraction was more profitable and less arduous to the hand miner. Nevertheless, underground mechanisation was encouraged and subsidised in a number of ways, despite the fact that mining was still restricted to a one shift operation.

In its pursuit of mechanisation the Joint Coal Board is credited with the introduction of the first Joy Continuous Miner into Australia in NSW in 1950. This machine combined the three separate phases of conventional mechanisation, i.e. cutting, boring and loading, into one operation by using rotating cutter picks to tear the coal from the solid face (thus avoiding the use of explosives), gathering the cut coal from the floor and conveying it to whatever means of transport was in use. The immense advantages in coal winning conferred by this machine were the reduction in manning from three separate operations to one, and fewer coal faces to maintain, ventilate and service.

By this time a general appreciation of the benefits accruing from the use of machines was becoming apparent, so that in 1954 the ban on the mechanical extraction of pillars was lifted. This allowed full use of the capital invested in mining machinery for coal winning, and as a result by 1959 the percentage of coal mechanically loaded had risen to 38.8 per cent.

The advent of the continuous miner, which simplified and made safer the function of pillar extraction, led to a demand for multi-shift operation from the colliery proprietors, so that by 1963 the production of coal by continuous miners on the second shift was equal to 40 per cent of the production of coal by continuous miners on the first shift. From this time on, with mechanisation fully established, hand mining went into a rapid decline and has not been used as a production function for many years.

Australian Academy of Technological Sciences and Engineering