I was fortunate enough to have been trained by some vastly experienced coal miners, some of whom commenced their mining careers in the 1930s, well before the advent of hydraulic roof supports and high powered electrical cutting machines.
Back in those days, it was Geordie props, split bars, lids, picks and shovels. “High technology” was compressed air.
In this column I have itemised what would have made a good longwall operator back then and compared it with today’s ideal operator.
The 1940s Northumberland longwall operator
A typical longwall in 1940s Northumberland longwall would be 100 yards long, perhaps 40 inches high, supported by Geordie props (the width of a man’s leg) and steel bars.
The coal face would be undercut by a machine resembling a very large chain saw, followed by boring and firing (blasting) and then the coal would be filled out onto a rubber conveyor belt. The final cycle was to dismantle the conveyor and advance the props and bars. Note: face creep was not an issue.
In those days, the word “geotechnical” had not been invented and any aspect of environmental monitoring or strata control, was executed using the five human senses of touch, smell, hearing, sight and “pit sense” – the latter coupled with “pit craft”
Before the advent of longwall visual analysis and convergence monitoring, the miners would “listen” to the strata and the wooden props holding up the roof. Wood props were preferred over steel props as they would “talk” under load, providing warning of impending danger. A miner could tap the roof with the wooden shaft of his pick and know if the roof was good or bad.
The old miners could detect a heating by smell long before the sampling systems would show anything at all.
I worked with a safety engineer in Yorkshire who “sniffed out” heatings weeks before there was scientific evidence and yes, he was well endowed with facial features that were an inspiration for the space shuttle.
There will be a handful of people reading this who will remember Peter Jerenik.
Looking at the condition of the roof, the ribs and the floor would indicate the pressures being exerted on the working coal face. Another sign was the sap being squeezed out of timber chocks. The partings and breaks in the coal would expose the hidden perils that lay beyond the next web of coal.
An old deputy would tap the roof and sides with his stick and “feel” for breaks, while listening for the hollow note that could indicate an impending roof collapse. Changes in pressure and direction of the air might indicate a distant goaf fall, or something far worse.
I define this as “awareness” of the mining environment and the ability to respond to the mining challenges and the constant potential dangers.
These are the skills handed down from generation to generation of coal miners. Not all coal miners possessed pit sense or pit craft but the ones that did were as skilled and as talented as any engineer, tradesman or artist that I have met.
In the “old days” (right up until the 1980s in fact) roof cavities were timbered up by miners working inside huge cavities in unsupported ground. Timbering of cavities required great skill but it was highly dangerous and often lethal. This is one skill I am pleased is no longer employed in our coal mines.
Today’s longwall operator
Today’s longwall operators may be a world away from the hand-hewn faces of the past, the only common feature being the coal seam itself.
The modern longwall is a custom-designed integrated assembly of equipment costing $200 million or so.
They may consist of up to 200 computerised powered roof supports that can individually support the weight of two fully loaded Airbus A380s; steel conveyors that can move 5000 tonnes per hour of coal; coal cutting machines more powerful than 4000 horses that can cut and load 5000tph.
The skills required are very different to the old miners of the past but require a far higher level of training and expertise and a broader spectrum of skills.
The five senses alone are not enough. Modern longwall operators have to interact with computers, automation systems and “smart” machinery.
It is mandatory to wear ear protection to prevent damage to our noise-sensitive ears. Hearing has limited use most of the time during production other than for communication. In some instances, hearing can be useful for horizon control (picks on a stone floor).
Everyone on the coal face wears dust masks. However, even the slightest smell of combustion is highly noticeable underground. This remains an important sense.
Everyone underground must wear eye protection. The modern coal face in particular is extremely hazardous to the naked eye. However, sight is the most important sense on a modern longwall. Sight is essential around moving machinery for safety reasons, for horizon control, for reading computers, for identifying problems, for checking alignment, or for seeing alarms.
All contact with the coal seam is entirely though heavy-duty machinery and so touch only applies during interaction with the machines or, in modern speak, the user interface.
This is still very important. Situational awareness is essential for safety. It is also essential for understanding roof control. Pit sense is not something you learn from a book. It is something you learn through practical experience.
This is perhaps where the biggest differences are found. The modern day longwall miner must have a sound knowledge of:
- Computers. The modern longwaller does not have to be a software programmer, but needs to be competent and conversant with a variety of computer systems for equipment monitoring and operation. Systems such as (but not limited to) LVA, V-Shield, PMCR, RS20S and many more;
- Strata control: a basic understanding of how the strata behaves around a longwall and a complete understanding of the functions of a powered roof support;
- Horizon control: everyone on a longwall must understand the importance of horizon control and the implications of getting it wrong. They must also understand what actions to take when they see it go wrong;
- Armoured face conveyor creep control: this may not have been an issue in the old days but it is potentially catastrophic if it gets out of control. Creep control requires constant vigilance and immediate actions on the part of the longwall crew;
- Face alignment: directly within the control of the longwall crews, the longwall must be kept straight and all team members must recognise this;
- Teamwork: the modern longwall environment requires teamwork. Everyone has a role to play within the team. If you are not a team player, you should not be on a longwall; and
- Health and safety: most importantly of all, longwall miners must have a thorough understanding of safety systems, no-go zones, the automation cycle, isolation procedures, risk analysis, safe working procedures and personal protective equipment requirements.
The modern longwall operator requires many skills and the ones discussed are only during “normal operations”
The additional skills required for longwall relocations and roof falls would require another, longer column.