LONGWALL mining

THE FUTURE

There have been many predictions of what the future will be like in all sorts of fields as well as mining, most of which have proved to be wildly inaccurate, usually on the optimistic side, and therefore it is not intended in this document to make predictions without qualifications.

Comments will refer to work where progress appears to be being made towards certain aims and directions progress is expected to be taken. Up to recent times, apart from improvements in longwall management systems (organisational and personnel management), longwalls have become more productive mainly by adding more and more power, particularly in thicker seams which have become more accessible, often as open cut workings have reached their economic depth limits. This method of productivity improvement cannot continue as size brings its own problems related to weight of equipment, extra space required to install the equipment and in some cases the additional heat generated. Other ways must be found to improve productivity, always with an eye to improving safety at the same time.

There is, no doubt, still room for improvement in organisational and personnel management systems to varying degrees across the industry and some changes will be evident in this area, but the best system for a given operation may well be different from others in different conditions and may even vary from time to time at a single operation where conditions vary during its life.

An increase in the use of automation to varying degrees is to be expected. As previously noted aspects of automation are already in use or at least available at some, probably most, longwall mines. Some well respected experts are of the opinion that almost unmanned faces will be operating in the next few years. While this may be true for some locations with very uniform and relatively uncomplicated conditions, others are of the opinion that a longer time scale will be involved for this aspect of progress. Even if a face is essentially operating automatically, it is likely that most mines will feel a need to have personnel in place to "keep an eye on it" for some time yet, until it is proven to be reliable and effective. Much depends on the degree of knowledge of variations in strata conditions and so developments in other fields, notably improved (possibly continuous) logging of boreholes could have a large effect on the success of automation. Even where aspects of automation have been proven, unless retrofitting is practical its use will be delayed simply because mines cannot afford to discard existing equipment to replace it with automated equipment, unless increased productivity or reduced costs can justify such action. The extensive use of full automation is therefore likely to take place over a long period.

Longwall top coal caving has started to be used (at Yancoal Australia Pty Ltd's Austar Mine) and its use is expected to increase in the mid to long term. The main driving forces are likely to be:

  • maximisation of resource recovery, probably at a relatively low incremental cost per tonne, and/or
  • the possibility of reducing equipment size, enabling the normal longwall cutting part of the process to be carried out at a comfortable (and safer) height, while still maintaining high production and recovery levels.

Communications are likely to continue the improvements made over recent years to the extent that communications between individuals may become possible without the need to travel to a phone or use loudspeaker/radio type instruments – the use of instruments in the form of individual mobile phones, possibly attached to safety helmets, may be introduced. Such instruments may be combined with a location/tracking device. Personal radios and tracking devices are already available and in use, but it is to be expected that these will become more personal (individual units rather than radios able to be heard by other personnel, for instance) and probably less bulky. Monitoring of machine information and the use of CCTV to provide information to remote locations, particularly surface, is likely to become more widespread and long distance remote control of some machinery more common.

Improvements in dust control/capture are desirable to enable personnel to have the freedom to work at any location regardless of the type of cutting process used. Work is in progress in this regard.

Ventilation is a limiting factor for many installations, particularly gassy mines, and the future is likely to involve larger fans and greater use of booster fans to allow higher production rates. Again improvements in drilling technology allowing improved gas capture in drainage systems may reduce the requirement for better ventilation to some degree. Improvements in roadway development (in rates and costs) could allow drivage of additional airways, thereby also reducing the need for greater ventilation power.

Where the future actually takes us is dependent on many factors, not the least of which is financial. It is possible for lower coal prices to provide an impetus to improve productivity. However, most improvements, particularly for large changes, require a considerable investment in time and money, with the consequence that there is a tendency for progress to increase in the good times.

Thankfully coal mining overall, even to some extent including equipment manufacturers, has a history of sharing information rather than using secrecy to try and gain a financial advantage, possibly because so much of the work involves improving safety as well as productivity. This attitude enables shared costs for research through organisations such as ACARP and can avoid a lot of wasted effort "re-inventing wheels" or repeatedly going down the same blind alley. Even so, research resources are limited and future developments will be concentrated in areas where the industry as a whole sees the greatest need or greatest return for effort at that time. This vision can frequently change depending on market conditions, government regulation, taxation issues (particularly possible carbon taxes at present) often disguised under some other name, public opinion and perceptions, etc. Such changes can easily alter what is currently a vision of the future and revise the priorities to which the finite research resources are applied.