Stamp mill

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Model of an Upper Harz stamping mill in Lerbach
Stamp mill in operation in the Fretter bone mill

A Pochwerk or a Poche , also known as a stamping mechanism, shock mechanism, percussion mechanism or Pocherich, was a machine used to crush ore . Stamp mills were mostly integrated in the smelters and iron hammers . The technical manager of a stamp mill was called Pochsteiger . A permit from the mining authorities was required to operate a stamping mill. Stamp mills were also used in other stamp mills , such as oil mills , tinder mills , bone mills , blue ink mills and powder mills .


The raw ore from the ore mines had to be processed before being smelted . Some ores had such a low metal content that they first had to be smashed in order to be able to process them further. Such low-grade ores were referred to as throbbing. Depending on the grain size achieved, the respective punching process was called coarse pounding, Rösch pounding or fine pounding. With coarse punching, grain sizes between four and eight millimeters are achieved, with Röschpochen the grain sizes were two millimeters and with fine punching one millimeter. The resulting crushed ore was known as punching flour or punching stuff. If the punching flour was sharp-edged, it was called the crunchy witness ; if it was only slightly rough, it was called the mild witness . If the pounder did not pay close attention to the pounding process and the ore was pounded too long, the ore particles were crushed into fine flakes. These platelets could not be used for further processing because they floated on the water and were washed away. Such particles were said to be “the ore was knocked to death”.


Modeled on the stamp mill of the former Saigerhütte Grünthal in the Ore Mountains

A well-documented written mention shows that the first dry stamping mills were used as early as 1492 in S-charl in south -eastern Switzerland. The first wet stamping mills were used in the Schwaz mining industry around 1512. This technology was later passed on to the Saxon Ore Mountains. A stamping mill was built in Schneeberg between 1752 and 1753, with which the cobalt ores were stamped. In Ramingstein in the Lungau mining district there were four stamping works in the 16th century. These stamping mills were in operation until 1782. In the Upper Harz there were once numerous stamping mills for crushing the ores extracted. It is known from Goldlauter near Suhl that up to eight separate stamping works existed in the Goldlauter valley there in the 16th century. That is why parts of the valley are called “Pochwerksgrund” today.

In (former) mining areas there are house, place and field names that refer to stamp mills:


There were dry and wet stamping works. Wet stamping machines were very similar in structure to dry stamping machines, there were differences in the size of the stamping shoes and the stamping sole. The stamping tools from the dry stamping works were then transported to the sieve for further processing. Wet pounding mills served as it were for washing ore , whereby the ore contained in the pounding agent was enriched by means of gravity separation . The pounding tools from the wet pounding were processed further on the shock stove or the sweeping stove. The flood remained of the throbbing turbidity as a remnant of the settling process. The flood no longer contained any usable ores. The wet process enabled safer and cleaner handling of the materials to be thrown.


Stamp mills consist of several components. The frame of the stamping mill is the stamping chair, in which the stamping stamps are guided. Each stamp is in its own section. Three to five stamps form a stamp. The stamping sole is located under the stamping chair; the ore is filled into this stamping stamp and crushed by the stamping stamp.


Stamp mill with five stamps in a gold and silver mine in Idaho, USA

The punch chair was constructed differently depending on the type. The heavier the stamps, the more stable and heavier the punch chair had to be. Usually it was made of wood. Struts were used to fasten the stool so that it would not wander back and forth due to the vibrations caused by the movement and the impact of the stamp. In some mining districts, the punch stools were placed on firm ground. To do this, the upper layer of the earth was removed about five to seven feet . Where this was not possible, foundations were made from heavy beams.


The stamps were also called Pochschiesser. Squared timbers, mostly made of hardwood with a thickness of six to seven inches, were used as stamps. Two pairs of guide sticks were used to guide the stamp, which had to be attached to the sticks on the side of the stool, the stamp pillars, at a precisely coordinated height. If the upper pair of guide timber were attached too high above the stamping sole, the stamping chair had to be provided with additional lateral supports in order to have a sufficient stand. In wet stamping works, the lower pair of guide wood should not be attached too close to the stamping trough, as it loses its abrasion resistance due to the splashing water and it wears out more quickly due to the moving stamp. At the lower end of each punch an iron ring, called a punch shoe or punch iron, was attached. The punch shoe was subject to high wear and tear and was therefore exchangeable. So that the pouch shoes had the longest possible service life, they were made of hard materials, usually extra hard cast iron . In order for the punch to have a sufficiently high impact force when it hit the ore, it had to be positioned in the punching chair so that it hit the ore to be crushed from an average height of eight inches . The height of the fall of the punch was adjustable and should not be more than twelve and not less than four inches. The weight per stamp was between 100 and 500 pounds. Lighter stamps were less suitable, as more stamps were required per stamping unit for the same stamping performance. Heavier punches were also not well suited, as they were more difficult to handle and, due to their weight, the lifting parts of the stamping mill had to be designed to be more stable. The mean weight of the punches used was about 300 pounds.

Tampon sole

Wet stamping after Agricola

The stamping sole formed the bottom of the stamping mill, on which the ore was crushed with the stamps. The punch sole had to have great strength and hardness. So-called "halved" cast iron was mostly used as material. The pouch sole was usually more durable than the pouch shoes. Square plates were used that could be used on both sides and turned over up to four times. If one side was worn, the individual plates of the punch sole were turned over. The material used for the punch sole was a maximum of four inches thick. Stronger material was not required as the wear on the material did not exceed 1.5 inches per side. The length and width of the pouch sole was dependent on the dimensions of the pouch shoes. The cast iron punch sole had to be placed on a flat surface. As a rule, plates made of cast iron were also used for this. However, these panels were at least six inches thick, up to twelve inches if necessary. These greater material thicknesses were necessary in order to counteract the vibrations caused by the stamping of the stamps. There were also stamp soles made of very hard stones, these were put together in wooden boxes. These stone soles were more durable and easier to repair; when the stones were trampled, new stones were refilled. However, the stones could get mixed up when punching and the stone punch sole required a deeper substructure than the cast iron punch sole.

Punch trough

In wet stamping works, a stamping trough was built in instead of the stamping base; it had the same task as the stamping base. The pouch was made of oak or beech wood. The trough had to have a solid base just like the bottom of the tap. If the ground was too soft, a foundation made of wooden planks was created. The joints between the woods were sealed with thin cloths or moss so that the pot was sealed. On the side of the trough had an opening through which the mixture of crushed ore and water could run out. The smelting man called the water filled into the pounding trough for the throbbing process, and the ore water ( suspension ) he called throbbing. A form made from three pieces of wood, the so-called channel , was built on the pochette . At the end of the channel there was a settling trough, which was called a swamp. The pounding pulp flowed from the pounding trough over the channel into the swamp.


Stamp mill with drive, view from behind

The stamp mill was usually powered by a water wheel. There were also stamp mills that were powered by animal muscle power or later also with a steam engine. The drive machines were coupled to the punch shaft that protruded from the punch chair. This shaft was provided with embedded pins, so-called Heblingen. These Heblinge in turn operated so-called Däumlinge, which were provided with a mechanism with which the stamps of the stamp mill were moved. Because of their low efficiency, gnepfen (water seesaws ) were only rarely used.


  • Johann Hübner: Newspaper and Conversations Lexicon, thirty-first edition, third part: M to R. Gleditsch, Leipzig, 1826, pp. 585-587 online .
  • Hans-Joachim Kraschewski: The punch work. Innovative tools for ore processing in the pre-industrial ironworks of the Harz . In: Scripta Mercaturae. Journal for Economic and Social History, vol. 47, 2018, pp. 73-100

Web links

Commons : Pochwerk  - collection of images, videos and audio files

Individual evidence

  1. a b c d e f Explanatory dictionary of technical art expressions and foreign words used in mining in metallurgy and in salt works. Falkenberg'schen Buchhandlung publishing house, Burgsteinfurt 1869.
  2. ^ A b Moritz Ferdinand Gätzschmann: The processing . First volume, published by Arthur Felix, Leipzig 1864.
  3. Der Pochsteiger (accessed on August 19, 2011).
  4. a b c d Georg Agricola: Twelve books on mining and metallurgy. In commission VDI-Verlag GmbH, Berlin.
  5. a b c d e Moritz Ferdinand Gätzschmann: Collection of mining expressions. 2nd edition, Verlag von Craz & Gerlach, Freiberg 1881.
  6. a b c d e P. Ritter von Rittinger: Textbook of the processing customer. Published by Ernst & Korn, Berlin 1867.
  7. ^ A b c d Carl von Scheuchenstuel : IDIOTICON of the Austrian mountain and hut language. kk court bookseller Wilhelm Braumüller, Vienna 1856.
  8. a b Mineralienatlas Lexikon: Pochwerk (accessed on August 19, 2011).
  9. Bergstadt Schneeberg: From ore to cobalt color ( Memento from April 2, 2016 in the Internet Archive ) (accessed on August 19, 2011).
  10. The Pochwerk Kendlbruck (accessed on 19 August 2011).
  11. Wilfried Ließmann: Historical mining in the Harz. 3rd edition, Springer Verlag, Berlin and Heidelberg 2010, ISBN 978-3-540-31327-4 .
  12. Silver and copper mining near Goldlauter. (accessed on August 19, 2011).