Mining in the Upper Harz
Mining in the Upper Harz region of central Germany was a major industry for several centuries, especially for the production of silver, lead, copper, and, latterly, zinc as well. Great wealth was accumulated from the mining of silver from the 16th to the 19th centuries, as well as from important technical inventions. The centre of the mining industry was the group of seven
.History
The Upper Harz was once one of the most important mining regions in Germany.[1] The major products of its mines were silver, copper, lead, iron and, from the 19th century, zinc as well. The main source of income, however, was silver. From the 16th to the middle of the 19th centuries about 40–50% of the entire German silver production originated in the Upper Harz.[2] The taxes raised from this contributed significantly to the revenue of the royal houses in Hanover and Brunswick-Wolfenbüttel and helped to secure their positions of power and influence within the empire.
Its lucrativeness justified a high commitment in terms of investment and effort. The Upper Harz mining industry produced a considerable number of innovations and inventions, including such important advances as the
In the Upper Harz, vein mining (Gangerzbergbau) predominated. Excavation followed the almost vertically standing lodes or veins (Erzgängen) downwards.[3] In their heyday the Upper Harz Mines were among the deepest in the world. For example, as early as 1700 or so shafts were already exceeding depths of 300 metres and, around 1830, a depth of 600 metres was achieved – which was considered significant at that time because it was below sea level.[4]
The Middle Ages
Mining activity in the Harz goes back to the 10th and 11th centuries.
Early Modern Period to the Industrial Revolution
A clear recovery followed from about 1520 onwards, initially at the instigation of the Duke of Brunswick-Wolfenbüttel, Henry the Younger.[1] But it was his son, Julius, Duke of Brunswick-Lüneburg, who gave added impetus to existing mining operations in the Upper Harz and initiated the creation of further infrastructure, especially the structures of the Upper Harz Water Regale to provide water power for the mines. In order to entice the necessary labourers, tradesmen and even mining companies to the Harz, the dukes granted 'mining freedoms' (Bergfreiheiten) based on Bohemian and Saxon practice.
Because the considerable energy needed to drain the mines increased as the mines became deeper and deeper, attempts were made early on to reduce energy consumption by driving drainage adits. This entailed cutting tunnels from the mine into the neighbouring valleys, through which water could drain away downhill under gravity. The deeper the water level lay, the longer these adits needed to be. The longest of these tunnels was the Ernst August Tunnel, built in the mid-19th century, which was 26 kilometres long. It collected water from the mines in Bockswiese, Lautenthal, Zellerfeld, Clausthal and Wildemann and transported it to Gittelde on the edge of the Harz.[3]
The Upper Harz mines attained their greatest productivity in the 16th and 17th centuries, even though there were frequent crises during that time. In 1690 the metal produced reached a quantity that was not exceeded until 1850. That was especially thanks to the construction of artificial water supply structures and the introduction of
Industrial Revolution to the Closure of the Mines
Following the annexation of the Kingdom of Hanover by the
Re-use for electricity generation
Following the closure of the mines in 1930, several shafts switched to the generation of electricity. Here, water from the Upper Harz Water Regale's network of ponds and channels was transported down chutes into the shafts, in which
Mining technology in the Upper Harz
Mining the ore
In the early days of mining in the Upper Harz simple
The packing (gangue material used for filling) from the upper main gangways was placed in the exhausted cavities (the so-called 'old man' or Alter Mann). This required the erection of a wooden ceiling over the active workings so that packing material did not fall into it and onto the face workers there. If the expected supply of ore or its quality did not justify sinking the main shaft deeper, or if the workings were a long way from it, draw-shafts were sunk. These blind shafts saved having to pack the 'old man'. In the Hornstatt, 1 or 2 labourers (Knechte) worked a hand winch and lifted the ore to the next highest main gallery.
From 1633
After clearing the blast debris, the material to be screened was loaded into wagons (Hunde or Hunte) using rakes (Kratze) and tubs (Trog). Larger boulders (Wände) were first broken up with sledges and crowbars.
From the second half of the 18th century the method of mining was reversed. Now the roof was always mined and so extraction proceeded upwards. That meant the miners worked on top of the packing and could transport the ore under gravity using so-called chute holes (Rollöcher or Rollen) rather than shafts. Overhand stoping remained the only mining method in the Upper Harz mines until the end and was perfected in the final years through the use of trackless wagons, roof bolts (Ankern), shotcrete and lean concrete packing. Trials with sublevel stoping (Teilsohlenbruchbau) and square set timbering (Blockbau mit Rahmenzimmerung) did not get past the experimental stage.
In the middle of the 19th century, the many individual pits transferred to larger mine complexes with central shafts, at which point the sinking of inclined shafts and the mixing of layout and equipment with the workings was abandoned entirely. The central, vertical shafts lay in the host rock (usually in the hanging wall), just as permanently established as the main gangways (usually in the footwall).
Extraction technology
To begin with the ore was chiseled free and carted to the surface of the open pits or shallow mines in baskets. Once shaft depths increased to between about 10–60 metres hand winches (Handhäspel) were used, operated by one or two workers (Knechten). The crude ore was placed in wooden buckets for transportation. For the rather short, horizontal gangways leading to the shaft the ore was carried in Trogs for several centuries (long before the introduction of blasting). In the 17th century the shafts reached depths of between 100 and 200 m. Ore could no longer be removed by hand and horsepower was increasingly used. The horses worked in a cone-shaped building, the Göpel or Gaipel, which housed a
Due to the availability of water power this system was used until the closure of the Clausthal and
Movement
Until the beginning of the 19th century the miners of the Upper Harz had to enter and leave the mine using ladders. Towards the end, for shaft depths of around 700 metres this took up to 2 hours of the daily work time. This effort was almost impossible for older miners. In 1833, master miner (Oberbergmeister) Georg Ludwig Wilhelm Dörell (1793–1854) came up with a simple, but ingenious mechanical method of getting in and out of the mine, the
Preparation of Upper Harz ore
The processing of minerals in the Upper Harz depended on the type of
In the
- Coarse crushing with a heavy sledge (later with crushing machines).
- Wet trommels). The ore is washed (and gangue removed) and sorted by size.
- Manual separation (Handscheidung) of the coarse lumps of ore, pure ore minerals (so-called rough ores or Derberze) were sorted, dry crushed and went straight on sale (to the smelters). The work on the picking tables (Klaustischen) was carried out mainly by women, the elderly and youths.
- Washing (Siebwaschen) of the 'smalls' (Grubenkleins) or ore dust (Feinerze) in water-filled jigging tubs (Setzfässern). By dipping an ore-filled sieve several times in water the heavier pieces that were more ore-rich, settled in a lower layer. This process was later mechanised using jigging sieves (Setzmaschinen, not to be confused with the Setzmaschinen used in crushing).
- Wet stamping (Nasspochen) of ore which is more finely mixed with the gangue until it forms a 'sand'.
- Separation of the stamped ore on tables (Herdwäschen) using gravity. Depending on the design and drive mechanism, they were called vanners (Planherde), percussion tables (Stoßherde) or rotating tables (Rundherde). The fundamental principle was that heavy particles of ore remained on the table and the gangue would be washed away by water.
- The slimes or tailings from the preceding set of processes were further separated from the particles of ore in tyes (Schlammgräben) by sedimentation.
The resulting concentrates (Schlieg or Schliech) were sold to the smelters. The preparation of the different types of ore was carried out as far as possible by visually sorting the concentrates by hand in order e.g. to separate out lead from copper concentrates.
After 1850 the small and scattered stamp mills and ore washeries were replaced by central ore dressing plants. The basic steps - coarse crushing - manual separation - sieving - jigging - fine crushing - table work and slime washing - remained much the same. The process was increasingly mechanised and perfected. In 1905 the most modern ore dressing plant in Germany went into operation in Clausthal using the gravity dressing process. It was located near the
Smelting in the Upper Harz
Mining in the Upper Harz is inextricably bound up with metallurgy. It is the preparation and smelting of ore that enables metals to be extracted and used. Only by adapting and developing the smelting processes over the course of the centuries could mining in the region be maintained, because the lodes changed their primary metal content sharply with increasing depth.
The beginnings of smelting go back to the start of mining in the Upper Harz in the
In the second major phase of mining in the Upper Harz from 1524, smelting was gradually moved into fixed sites. The transportation of logs as
From the first mining period until just before the industrial age the so-called precipitation method (Niederschlagsarbeit) was used in the Upper Harz. Instead of the usual roasting (desulphurising) of the ore, the slag was melted using charcoal with granulated iron (Eisengranalien) as a reduction medium using the roast-reaction process (Röst-Reaktions-Verfahren) (direct conversion from metal sulphide to metal) in arched kilns (Krummofen). The comparatively low kiln temperatures of around 1000 °C produced no liquid slag, the residue (gangue) remained in solid form. Not until the development of more powerful fan shaft kilns around 1850 were the concentrates roasted in double-deck ovens (Etagenöfen) and sintering pans and then melted in crucible shaft kilns (Tiegelschaftofen) on silver-containing argentiferous lead (Werkblei) and molten slag. The argentiferous lead was initially worked immediately in the German tests on lightened silver. At the start of the 20th century a multi-stage refining process was carried out in Kesselherden and silver extracted using the Parkes process.
Mining and forestry
The steadily rising demand for wood from the pits and smelting works led to overexploitation of the forests by the Early Middle Ages. Construction wood was needed above ground for accommodation huts as well as mining and smelting buildings. Below ground it was needed to extend the pits. The greatest consumption of wood, however, was for the smelting of ore with charcoal. There were some 30,000 wood billets in the Harz alone.
By the Early Middle Ages ore had to be transported over kilometres to the smelting works due to the lack of wood. One particularly well-known route is the transportation road from Goslar's Rammelsberg on the northern edge of the Harz over the Upper Harz to Riefensbeek and Kamschlacken on its southern perimeter. Traces of the road may be seen at many places in the Upper Harz forests.
From the 18th century a systematic reforestation of the largely destroyed forests was begun. As a result, the Upper Harz contributed significantly to the development of modern forestry. Although not typical of the region, fast-growing spruce trees were exclusively grown in monocultures. The consequences of this intensive forestry, which continued until the 1970s, are still to be seen in many areas of the Upper Harz today.
Because the shortage of wood was time and again one of the limiting factors for mining and smelting, the forestry situation was a standing agenda item at meetings in the mining office.
See also
- List of mines in the Harz
- Mining and metallurgy in medieval Europe
- Mining in the Lower Harz
- Upper Harz Mining Museum
- Roter Bär Pit
- Samson Pit
- Kunstgraben
- Kunstteich
References
- ^ a b c Gerhard Fleisch (1983), Die Oberharzer Wasserwirtschaft in Vergangenheit und Gegenwart (in German), Clausthal-Zellerfeld: TU Clausthal
- ^ Friedrich Wilhelm Conrad Eduard Bornhardt (1929), Blei-, Silber- und Kupfererzeugung im Oberharz und am Rammelsberg (in German), Landesamt für Bergbau, Energie und Geologie Clausthal, IV B 1b 151
- ^ ISBN 3-89720-725-7
- ^ Friedrich Wilhelm Conrad Eduard Bornhardt (1934), Wilhelm August Julius Albert und die Erfindung der Eisendrahtseile (in German), Berlin: VDI-Verlag
- ^ Dieter Stoppel (1981), Gangkarte des Oberharzes (in German), Hannover: Bundesanstalt für Geowissenschaften und Rohstoffe
- ISBN 3-923605-42-0
- ^ Christoph Bartels (1992), Vom frühneuzeitlichen Montangewerbe bis zur Bergbauindustrie (in German), Bochum: Deutsches Bergbaumuseum
- ^ Christiane Segers-Glocke (2000), Auf den Spuren einer frühen Industrielandschaft (in German), Hameln: Niedersächsisches Landesamt für Denkmalpflege
- ^ Asmus, Bastian (2012). Medieval Copper Smelting in the Harz mountains, Germany. Bochum.
Sources
- Bastian Asmus (2012), Medieval Copper Smelting in the Harz Mountains, Germany. Bochum: Deutsches Bergbaumuseum. ISBN 3-937203-63-X
- Martin Schmidt (2005), Das Kulturdenkmal Oberharzer Wasserregal (PDF) (in German), Clausthal-Zellerfeld: Harzwasserwerke, archived from the original (PDF) on 2009-04-19, retrieved 2010-05-02
- Hardanus Hake (1981), Bergchronik (in German), Goslar: Harzverein für Geschichte und Altertumskunde e.V.
- Christoph Bartels (1992), Vom frühneuzeitlichen Montangewerbe bis zur Bergbauindustrie (in German), Bochum: Deutsches Bergbaumuseum
- Christiane Segers-Glocke (2000), Auf den Spuren einer frühen Industrielandschaft (in German), Hameln: Niedersächsisches Landesamt für Denkmalpflege
- Dieter Stoppel (1981), Gangkarte des Oberharzes (in German), Hannover: Bundesanstalt für Geowissenschaften und Rohstoffe