Hand drilling in the Cobalt mines
Pure muscle power - The history of hand drilling.
Hand drilling was a long-standing mining method in Norwegian mining. It had its beginnings around the middle of the 17th century, but became a widespread mining technique during the 18th century. The method was introduced together with gunpowder blasting. The gunpowder had to be poured into a hole if it was to be effective, so hand drills were used to drill out such holes. The first Norwegian mine to experiment with gunpowder blasting was the Lilledal copper mine in Hordaland in 1655.
As mentioned, it wasn't until the 18th century that gunpowder blasting and hand drilling gained a firm foothold in Norwegian mines. This made many mines more efficient and displaced a number of older mining methods. If the operation went horizontally inwards, i.e. stoll mining, firesetting was generally still used, but if the operation went vertically, hand drilling and gunpowder blasting were a better solution.
Hand drilling was primarily carried out by two men, but it could also be done by one to three men. The occupational group that carried out the drilling was called borhauere. The most common form of two-man drilling involved one man holding the drill and one man striking the blunt end of the drill with a sledge-like tool called a chisel. The man holding the drill had to turn it around about a quarter of the way round after the blows.
The equipment used was three drills, one short and thick, one of medium length and thickness and one long and thin. These drills were elongated iron rods with a steel-set tip (towards the end of the 19th century they switched to pure steel drills) that had a sharpened tip and a blunt end.
First, the drillers were instructed by the foreman, known as the stigern, on where to make holes. At the designated drilling site, the rock was examined. Loose rock was knocked loose with a hammer at the drilling site, and at the same time elevations in the rock were knocked loose so that the drill would not slip away when drilling began.
When drilling started, the shortest and thickest drill bit was used first. If a long drill bit was used first, before the drill bit had created a proper attachment point, it would be "difficult and awkward to turn and strike [the drill] and [it] would wobble a lot". As the hole got deeper, the middle drill bit was used and finally the longest and thinnest. As the drill went deeper, it was easier to use a thinner bit, as thinner bits did not get stuck in the drill hole as easily. The length of the drill bit also increased to give greater reach.
The drill had to be turned slightly with each stroke. If the driller turned it too much, i.e. all the way round, the drill would hit the same spot, resulting in little progress. That's why it was important for the drill operator to turn the bit a little at a time "the subsequent blow makes a new groove in the stone, and if this is close to the first one, the stone in between also springs loose".
A little water was poured into the hole so that the boron meal, the broken stone, was driven out of the hole. This prevented the boron meal from forming a layer at the bottom of the drill hole, which would block further drift. The hole should not be too shallow or too deep. Morten Thrane Brünnich, the manager of the Blaafarve mill at the end of the 18th century, believed that the drill hole should ideally be somewhere between 18 and 30 inches deep (1 inch = 2.54 cm). If the hole was too shallow or too deep, the gunpowder would have no effect, making the work a waste.
Once the hole was drilled, a wiper was inserted into the hole. A wiper was a thin stick with a hole cut into the end. Through the hole lay a piece of cloth made of linen. This piece of linen was pushed down into the hole to remove the boron meal and moisture. The drill hole was now ready for blasting.
Cutting edge - Cobalt mines as pioneers of drilling innovation.
When cobalt was discovered in Modum in 1772, open-cast mining began. The cobalt ore was located at the very surface of the mountain, so the easiest way to extract it was straight out. Therefore, blasting and hand drilling were the natural mining methods. The first cobalt ore extracted from what was to become the Cobalt Mines was probably hand-drilled and blasted out.
In the cobalt mines, so-called chisel drills were used as early as 1788. On this type of drill, the cutting edge was shaped like an egg. In the silver mines, the older crown drills were used, where the cutting edge consisted of four edges that met in a point. When the Silverworks' management decided to replace the crown drills with chisel drills in 1796, a ladder and a blacksmith from the Cobalt mines were recruited to Kongsberg to teach the Silverworks' workforce how to use and forge this tool.
Koboltgruvene was the first mine in Norway to mechanise its drilling work. This happened almost 100 years later, in 1875, when pneumatic drills were used in the Cobalt Mines' longest and deepest adit, the Ludwig Eugen adit, which lies 160 metres below the Cobalt Mines' highest point and is 880 metres long. The pneumatic drills were made in Germany and consisted of a 13 HP steam engine, 1 air compressor with a cylinder diameter of 350 mm, 1 air reservoir of 6 cubic metres, an air line, 2 wrought iron pipes with a length of 345 barrels (1 barrel = 2 metres). The machine could turn 300 times a minute and had an output of 4 metres a month. This was double the output of hand drilling and lighthouse setting.
A diamond drill was also hired for ore exploration in 1890. With this, 4 holes were drilled. The longest hole was 60.38 metres and took 14 days to drill. Koboltgruvene was one of the first mines in Norway to use diamond drills.
The daily grind - Borhauern's hard everyday life at the Cobalt Mines.
The men who worked on drilling at the Cobalt mines were called borhauere. These workers had to have good knowledge of the mine's rocks so that he could drill good holes without too much instruction or help. Drillers worked in the open pit or underground. As the work was also heavy, the borhauers were adult men. Young boys were given lighter work outside the mine itself.
The Blaafarvewerk's management assigned the drillers a certain amount of work to be done each day. In 1827, each driller was to drill 30 inches per shift. In practice, this meant 60 inches per shift, as two men drilled together. More than 10 years later, in 1840, the labour requirement for the crew had increased to 80 inches per shift. However, the drillers had different labour requirements in winter and summer. There were 72 inches per shift in the winter and 80 inches in the summer. In 1842, a total length equivalent to 35.7 kilometres was drilled by hand in the Cobalt mines. At the same time, the average driller worked 304 shifts a year. Monday to Friday working hours were 11.5 hours, while Saturdays were only 6 hours.
Considering the heavy and dangerous work performed by the borhauers, it's not surprising that they resented being subjected to higher labour standards. When the Cobalt Mines hired a new mine manager in 1827, the new employee, Karl Friedrich Böbert, learnt that the Norwegian workers did not hesitate to speak up when they were dissatisfied. Böbert decided that the borhauers had to drill more for the same pay. As he put it:
"It is all too contrary to the interest of the work, when the labourers enjoy a constant and secure profit, and do not do what they can and should do."
As a result, the Borhauers were subjected to a greater labour requirement. This triggered a violent reaction, by the standards of the time, among the Borhauers at Sydgruvene. Böbert himself described it this way:
"This increase in the amount of work was, however, the cause of a general uprising among the labourers concerned, who all stopped work and wanted to push me back to the old system. Unacquainted as I was with the language of these rebellious subordinates, I nevertheless succeeded in bringing them back to obedience, by offering them the choice between either drilling 10 inches more than at present in each shift and receiving an additional half a specie, or drilling 6 inches more without additional payment. They preferred the latter, probably fearing that the first offer was only bait for further steps."
It would appear that the German managers regarded the Norwegian workers as ill-mannered, inefficient and conservative. New demands and working methods were met with scepticism and sometimes actively opposed. It seems that German workers were perceived as more docile and submissive, i.e. in the same way that German managers viewed an ideal worker.
The more pragmatic miner Müller, who ran mining operations for the competing cobalt plant Snarum Koboltverk, described his miners as follows:
"Every month, the borhauers change their workplaces according to management and the ladder's instructions. This prevents the impression of bias on the part of the factory. Norwegians, with their strong sense of freedom, are also the least likely of all to be treated unfairly."
The photo was taken by Gercke in the 1860s. This is inside the Cobalt Mines and is one of Norway's earliest industrial photographs.