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The Mining of Shale

Adapted by Harry Knox from his book "The Scottish Shale Oil Industry & The Mineral Railway Lines"

Mining

The methods of the mining shale changed little over the life of the industry and it was to be process which was not to use modern mining equipment to any great extent. Shale mining was to be hard, manual work during its lifetime. Basically, the Miner was a contractor, often known as a Placeman or Faceman, who undertook, for an agreed lump sum of money, to extract a specified amount of shale, or drive a pre-determined length of heading, per working shift. From this money, the Miner had to purchase his own explosives required, pay his Drawer or Drawers and pay for repairs to all equipment used. There was, in the early days, no set weekly wage. An average day’s work produced around three tons of shale or more per man, or linear progress of around 12 feet per week into the seam.

At the shale face (the workplace) the Miner made the holes in the shale into which the explosives were firmly placed, for firing. In the early days, these holes were dug out by the use of a very sharp, pointed pick but this less than satisfactory practice was soon overtaken by the use of hand-operated, ratchet drills. This consisted of the drill body, containing a screw which was extended in a rotary motion by the operation of the ratchet handle, worked backwards and forwards by the Miner. The drill body was supported on a suitably placed pit prop, (a boring tree) and a drill bit was secured to the screw end. As the screw wound out, so the bit drilled into the shale. When the screw was fully extended, the bit was replaced by a longer bit, and the process continued until a hole or holes of sufficient depth had been made. Into these holes, the Miner inserted cartridges of explosive Black Powder (Gunpowder) contained in strong paper tubes. When the explosive was firmly lodged in the hole and had been stopped up by a “paste” of shale dust and water, a fuse was inserted and lit by the Miner, generally from the flame on his lamp. The fuse was long enough to give the men to move to a place of safety. After the shots were fired, sufficient time was left for the fumes to clear before the Drawer(s) began to load, by shovel, the broken shale into the hutches. When full, the Drawer would push the hutch out to a haulage level where it, along with other loaded hutches were transported in trains, hauled by a pony, or later by a small locomotive, to the pit bottom. Each hutch carried an identification tag, and on reaching the surface, the tonnage was credited to that Miner.

Trials were later made with air operated drills but these were less than successful, however, electric drills were introduced in the early days of WWII, and using tungsten carbon tipped drills, the holes could be drilled in a much lesser time. In Breich Pit, which became something of a showpiece pit after the war, electricity was used for winding and longwall working was re-introduced, along with mechanical coal cutting machines and shaker conveyor belt systems to streamline the shale production process and eliminate much of the manual labour. The coal cutting machines were not a success since coal, unlike shale was a hard and friable mineral which was easily shattered. Shale was softer and denser in nature, and the coal cutters could not cope. Maintenance costs for both conveyors and coal cutters were much higher than had been allowed for, and that, with the non-success of the longwall working, led to the abandonment of the trials.

The actual mining teams of two or three men, were supported by the “on-cost” men. These were men not immediately involved in mining shale, but who followed on behind the mining operation by “brushing” the headings created, that is putting up proper supports for the roof, removing any waste, and in longwall mining, creating the packs, and also moving and extending the underground haulage-ways. As the name suggests, their work was an additional cost or an “on-cost” to the actual mining costs.

There were three basic mining procedures employed to mine shale, namely Longwall Mining, Stoop and Room Mining and Retreat, or Broken Mining. In a mine, the roof was, as to be expected, the top of the working whilst the floor was known as the pavement.

Longwall Mining

Longwall mining was widely used in the early days since it was a method understood by coal miners. Basically, the shale face was working over a length of 100 to 150 yards, with around 14 to 16 workplaces, known as “stints” spread over the length. Each stint was manned by a Miner and one or two Drawers working together as a team. The shale seam was undercut over the working length, mainly by hand, and later by the coal cutting machines. Above the undercut, a lower and an upper row of shot holes were drilled. Polar Ammon gelignite was used in the lower rows and black powder shots in the upper. The miner bored holes for the explosives and fired the shots. The Drawer(s) loaded the broken shale which had been brought down by the explosion, in to hutches which were then taken to the main haulage road to be included in trains of loaded hutches hauled by ponies (in the early days) en route to the pit bottom where they were lifted to the surface. Empty hutches returned the same way. Where conveyor belts were used, the shale was conveyed by this means to a central loading point adjacent to the main haulage roads. The roof of the working was supported at the face by timber pit props (trees) but behind the mining operating, packs of sleepers were built up and filled with waste material, to give better support to the roof. These packs lined the main headings.

Stoop and Room Working

Stoop and Room working largely replaced Longwall working at a later time, and, apart from some trials with Longwall in Breich Pit after WWII (described above), stoop and room became the norm. A series of headings, around 12 feet wide and 9/10 feet high were driven into the seams of shale at 12 to 15 feet intervals. As each workplace progressed, at about 12 to 15 feet depending on the inclination of the seam, cross headings were driven leaving pillars of shale around 12 to 15 feet square as roof supports. These pillars were the Stoops. The levels and workplaces were the Rooms. The mining technique and removal of broken shale was similar to Longwall working except that the workplaces at the face were generally smaller. There was no set dimensions for the stoops and in inclined shale seams, the stoops had to be longer in the inclined side to prevent “creep” or the sliding movement of the roof.

Retreat or Broken Working

Where Stoop and Room working had been employed and when the boundary of the pit or mine had been reached, so the Stoops that had been left supporting the roof, were recovered by removing them in a retreat operation. Each pillar was removed by a slicing technique (splits) and the roof was supported temporarily by wooden props. As the Stoops were removed, the props were also recovered and the roof which was then left unsupported, gradually fell in. This practice eventually caused subsidence problems on the surface, although the roof was not left unsupported under buildings or important structures. Retreat working was possibly the highest risk activity undertaken by the Miners in the pit.

Another short-lived method of shale extraction was trialled and this was opencast working of the seams which outcropped close to the surface. The earliest use of this method soon ceased but in 1946, with modern drag-line equipment, opencast extraction was again started at Whitequarries and at Livingston, but was finished in 1950.

The Mines and Pits

Basically, a mine consisted of an inclined shaft driven down at an angle to the horizontal into the shale seams and was the normal method adopted where shale seams outcropped at or near surface level.

A pit was a vertical shaft sunk down to access the deeper seams of shale.

In both the early pits and mines, normally only one shaft was provided for the purposes of an access for miners to the working areas and for the haulage of mined shale back to the surface. The inclined shaft contained two sets of narrow gauge railway upon which the hutches ran, one set for loaded hutches being brought up to the surface and the other for empties being conveyed back underground.

Later, Mining Regulations demanded that all workings were provided with two shafts, partly for ventilation purposes as described below, but more importantly, to ensure that there was an alternative emergency escape route should anything untoward occur in the underground access to the main haulage shaft. In shale workings, this escape facility was often provided by linking two adjacent pits / mines via underground tunnels.

Winding

Rope winding was employed in both mines and pits. In a mine, the rope, (later a wire rope) ran in a continuous loop to the foot of the shaft (the bottom). Here, loaded hutches were attached to the rope and hauled to the surface whilst empty hutches were returned by the same means. In the later mines, a special car containing rails transversely across the body, and on to which the loaded hutches, four at a time, were run and the car, with a heavier load of shale was then hauled up to the surface.

In pits, a wooden (and later) metal frames was constructed sitting across and above the top of the shaft, on which two large diameter wheels (whorls) were attached and over which the winding rope ran from the winding engine house. The loose end of the wire rope was attached to a cage, merely a metal platform and in the early days, otherwise unprotected, upon which both men and hutches could be raised and lowered into the pit. The winding of these cages was controlled from a winding house where a large winding engine provided the power. The Winding Engineman, a very responsible position, was provided with indicators which showed at which levels the cages were. The cages were held in position by guide ropes running the depth of the shaft and a buffer rope to prevent two cages colliding as they passed in the shaft. The early winding engines were powered by steam, but later, electrically-powered winding engines were provided.

Ventilation

From the earliest days of shale mining, there was a need to ensure by some means, a way of introducing fresh air into the deep workings and to encourage a circulation of air so that noxious fumes could be extracted. With single shafts, this was a problem, especially in the deeper pits. An early solution was to create a wooden barrier vertically up the shaft, in fact creating two shafts. The smaller shaft created, had a cube furnace provided at the mine foot, and, working on the basis that warm, or hot air always rises, so the heated, stale air rose up the shaft to the surface and fresh cooler air was drawn down the main haulage shaft, known as the downdraft shaft. However fire in a pit, any pit was a hazard, as was the wooden barrier, and inevitably there was a disaster at Starlaw Pit where the wooden barrier caught fire and eventually the flames burned through to reach the haulage shaft. This halted the raising and lowering of the cage and rendered the rescue impossible. Most men had been raised to the surface but as the fire ate through the partition, so seven miners were trapped underground and perished.

In later pits and mines, a second shaft was provided, mainly for ventilation purposes but also as an emergency access / egress shaft as required. This shaft was known as the updraft shaft and was fitted with a power-operated ventilation fan adjacent to the top of the shaft, which drew stale air from the workings. A series of screens and doors erected in the headings and levels of the underground workings ensured a good circulation of fresh air throughout the pit. Proper ventilation was essential for the safe operation of the mine or pit.

Explosives

Black powder (gunpowder), packed in stout paper tubes of varying lengths and weights, was the preferred explosive used in shale mining. It was an effective way of splitting and breaking the shale without shattering it into unusable sizes. In seams with harder mineral present, Polar Ammon gelignite was also used but being a high explosive, this did shatter and ruin the shale to a significant degree. The black powder was produced locally, at Camilty Powder Mill near Harburn, and consisted of 75 parts of saltpetre, 15 parts of carbon and 10 parts of sulphur. It was packed in stout paper tubes and, in earlier days, the Miners purchased the explosive from the local Co-operative ironmongery department (licensed under the Explosives Act), and they were certainly doing this up until WWI. From that time, Oil Companies were obliged to apply for a license to create a secure explosives magazine all pits and mines, located at a safe distance from the pithead, and, whilst this was a very piece-meal process in practice, the habit, which was widespread, of Miners taking unused shots home and throwing them in a cupboard, was eventually rendered obsolete.

The explosive was ignited by inserting “strum”, a rope like fuse with a black powder core, into the cartridge. The Miner lit the fuse, either by employing a chemical ignitor which was crimped on to the end of the fuse, and then crushed, the chemicals contained inside, then combining and producing heat, or merely by applying the flame on his lamp to the end of the strum, and he and his Drawer took refuge in a place of safety whilst the shots were fired. Shot-firing with black powder created noxious fumes and this was an ongoing source of complaint over the life of the industry. Even with very efficient methods of ventilation, it could take some time before the air in the far-flung working faces could be cleared.

Lighting / Illumination

Underground workings were, by their very nature, extremely dark places. There was, in later pits, electric lighting provided at the pit bottom and in the main haulage roads but in the working levels and headings, the only illumination was from the lamp carried by the Miners and Drawers in their caps. In the early days, these lamps, shaped like very small kettles, used animal fat (tallow) as a fuel. The tallow was softened by holding and rolling it in the hands and was then pushed into the container. A wick ran the length of the spout, and when this was lit, the heat generated, softened the tallow further into an almost liquid state and this melted fat was absorbed into the wick where it burned with, it must be said, a rather obnoxious smelling flame. This was known as a naked light lamp. These tallow (tally) lamps were gradually to be replaced by acetylene lamps, a more substantial lamp in two parts. The lower part was container into which calcium carbide was placed, and the upper part was a water reservoir. When the water, by means of a small valve, was allowed to drip on to the carbide, a chemical reaction took place which produced acetylene gas, a very flammable gas. This gas escaped through a small nozzle where it was lit, and provided a source of lighting, but it was was again, a naked flame lamp. These lamps were generally hooked into the miners cloth cap. There was however, one further lamp which was widely used, being a legal requirement, and that was the Safety Lamp

Shale workings were, in the main, and quite unlike coal workings, relatively free from gases, the various forms of gases, being known across the mining industry as “damps”, such as Firedamp, Stinkdamp and Whitedamp which were extremely flammable gases and Blackdamp and Afterdamp which were toxic and asphyxiants. These posed significant risks to underground safety.

In most coal workings underground, any form of naked flame was forbidden by Law and there were pit-head searches carried out on miners going underground to check for “contraband” the carrying of matches, lighters, pipes or cigarettes or anything which could generate heat or a flame. To carry such items underground was a dismissible offence.

In shale workings, however, these rules did not generally apply and shale workings were in the main, deemed to be naked flame pits. However, there was always the risk, however slight, of gases being released by the movement of the roof or falls of shale and rock. Thus Mining Regulations required that each workplace at the shale face, was inspected, and tested for gas once per day by a Fireman or Pit Deputy. These were responsible and specially trained personnel who used a Safety Lamp to carry out this test. The invention of the mining Safety Lamp is credited to Sir Humphrey Davy in 1816, but both George Stephenson (of railway fame) in 1816 and a Dr. Clanney, earlier in 1813, had also invented Safety Lamps, but all using basically the same principle of enclosing the flame in a wire gauze cone. Indeed, Dr. Clanney further improved upon the Davy Lamp at a later date. By surrounding the naked flame with wire gauze, so the heat of the flame was dissipated and kept below the flash point temperature of methane or other flammable gas. To test for gas, the Fireman would hold the lamp above head height in the workings. If methane was present, the flame burned with a distinctly blue colour. The lamp, when placed on the ground, if the atmosphere was in any way starved of oxygen, then the flame would extinguish, again giving due warning to the presence of an asphyxiating gas. The Miner, under a shale mining Special Rule, also had a responsibility to test the workplace each time after it was left unmanned (meal breaks etc) and had to ensure that no person with a naked flame lamp, re-entered the workplace until such testing had been carried out. It was a failure to comply with this special rule that led to the tragic explosion and fifteen fatalities in Burngrange No. 1 & 2 Pit at West Calder in 1947.

It will be seen that the actual illumination provided by any one of the lamps discussed would be very poor indeed, and so it proved. Things were to improve at a later time when battery-powered electric safety lamps were brought into use. The Miner wore a battery on his belt, capable of providing sufficient power for the lamp on his helmet, for a complete shift and these lamps were collected from, and returned to, a special lamp cabin on the surface, where the batteries could be re-charged when not in use. These provided a much improved level of illumination. Lamp cabins also held, and maintained, Safety Lamps.

Water Control

All underground workings, by their very nature, suffered from the ingress of water to a greater or smaller extent. In very wet pits, known as “dripping” pits, water could, and did flooding in at a rate of 600 to 800 gallons, and even more, each minute. There was no real alternative to providing pumps to control water levels and in the early days, steam driven pumps were employed. Electric power brought triple-ram and multi-stage turbine pumps which were extremely effective and by the 1950’s, multi-ram pumps were the norm across the industry. Not every pit or mine suffered in this way but there were some very notorious wet pits.

Underground Haulage Systems

Quite basically, this consisted of railway tracks of 2 feet gauge (ie two feet between the running rails), of light construction and thus easy to move and alter to suit circumstances, upon which hutches ran. These were quite simply small, four-wheeled wagons holding around 28 cwt of shale when loaded, and because friction was minimised by steel wheel on steel rail, could easily be moved by one person. The Drawers were responsible for taking loaded hutches out of the working headings to a level where the hutches could be attached to a continuous rope running between the rails, to be taken to the pit bottom, or made up into small trains, pulled by a pony to the pit bottom. Later, small diesel electric or battery electric locomotives superseded the ponies, and these, rated at 12hp. could pull heavier trains of loaded hutches (up to 30 at a time) along the underground haulage ways and even on rising gradients.

In seams which were steeply inclined (from the horizontal), there was a problem controlling loaded hutches descending the inclined track and hauling empty hutches back up the incline to the working face, for re-loading. This problem was addressed by employing by one of two methods. This was a simple application of applied mechanics to a special problem, and it worked. These were “Cousie Braes” and “Cuddie Braes” where, in the former, loaded hutches descending were attached to empty hutches to be pulled up, by means of being secured to a chain passing over a pulley near the working face. The loads descending were counter-balanced by the empties on the way up. In the latter method, a permanently heavily-loaded hutch, the cuddie, running on an adjacent, but separate inclined track and again using the principal of a chain and pulley, was used to counterbalance loads descending, by itself being hauled up the incline, and when it was descending it pulled empty hutches up. Simple, but it worked and served the industry well.

The underground workings were dark, often wet and humid, insanitary places with no toilet facilities or indeed, running water, and where men, and in the days of the pit ponies, the ponies worked and ate together.

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