Segregation
Segregations (obsolete also Saigerungen to, segregate , purify, separate ', related to strain , it segregates separates from the rest of the melt) are segregation of the melt in the metal fabrication which directly given to a local increase or even decrease of elements within the mixed crystal to lead. They arise when the melt changes into the solid state. The different solubility of the alloy elements in the liquid and solid phase and, among other things, the different density of the alloy elements play a role. Segregation results in different material properties within a casting .
A distinction is made between micro segregation (on the crystal level ) and macro segregation in the order of magnitude of the casting.
The Seiger or outdated Saiger process is a smelting process with metal enrichment using this method that has existed since the Middle Ages .
Micro segregation
Differences in concentration during the formation of mixed crystals lead to the formation of micro- or crystal segregations . This difference in concentration is compensated for by diffusion processes when the solidification is very slow . In technical solidification, i.e. H. In the case of solidification that is not close to equilibrium, the concentration compensation by diffusion is not possible due to the rapid cooling. These crystal segregations are the only ones that can be dissolved again by homogenizing annealing .
Macrosegregations
Block segregation
As Blockseigerung segregation are throughout Cast referred. This is the same process as with crystal segregation, but on a larger scale with the solidification of an ingot. Since the solubility of impurities in the solid is lower than in the melt, they collect in the residual melt. Because the melt solidifies from the outside in, the last center of the casting that solidifies is over-saturated with the typical accompanying elements carbon , phosphorus and sulfur .
Segregation occurs when a steel melt cools down . In the case of some copper alloys , inverse block segregation can occur. Here an accumulation of foreign substances occurs at the edge.
Gravitational increase
The increase in gravity often occurs with lead and tungsten alloys. Here segregation takes place due to the different density of the alloy components. It can only be counteracted by slowly rotating the casting mold and the melt during solidification.
Silver mining
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History and principle
In front of the Nuremberg Frauentor there was a municipal Saigerhütte from 1419 at the latest, in which the new Saiger process was used. This was a significant technological advance and at the same time the most momentous mining innovation in the field of non-ferrous technology. Until then, silver contained in copper ore could only be obtained economically if the silver content was more than 0.5 percent.
The principle is based on the fact that silver dissolves much better in lead than in copper in the melting process. Black copper containing silver , with a copper content of approx. 70 to 96%, is therefore fused with about three times the amount of lead and the silver contained in it is extracted from the copper. The lead , which is now silver-containing, from this melt, also known as lead , is largely melted out in a further step in special Seiger furnaces. A technologically-related silver content of 0.02% remains in the copper, which at that time no longer interfered with the further processing of the copper. The copper was then refined by drying and cooking. The recovered lead-silver alloy is in the driving process, even Kupellation (histor. Fining ), separated from each other. The fine silver obtained by Seigern gained a considerable share of the silver market.
This made lead mining for silver mining - just like mercury mining for gold mining - an important branch of industry.
The first Seiger huts are built
The higher mountain shelf , which also included mining for silver, remained almost without exception with the sovereign. With the discovery of the process, the owner of the smelter succeeded in obtaining possession of the silver contained in the copper ore, which was not subject to delivery. The prince's share in the copper ore was already paid for with the tithe, and the owner of the smelter was free to dispose of the molten metal in terms of quantity and price. The metal trade quickly recognized the importance of the process, which prompted merchants in this trade to build large Saiger smelters.
First of all, Nuremberg patricians appeared with the establishment of Saigerhütten or Saiger trading companies. At that time, Nuremberg was one of the most important centers for metal processing in Europe. The metal trade as the owner of the smelters secured the supply of raw materials. Due to the high demand for water power ( water wheels ) and wood (for the production of charcoal ), the first Seiger huts were built mainly in water and wooded areas of the Thuringian Forest . Along the trade routes crossing the mountains there were favorable opportunities for their establishment. Between 1461 and 1565 created twelve huts, of which Saigerhütte Schleusingen of November 20, 1461 , Count Wilhelm von Henneberg-Schleusingen was licensed - concessionaire was the Nuremberg citizens Martin Semler. At the beginning, mainly copper from the area around Mansfeld was exported as the silver content was higher than in other mining regions. The operation of the aforementioned Saigerhütten led to Thuringia being a leader in copper and silver metallurgy for about a century. When Sachsen-Zeitz fell back to Kursachsen in 1718, the history of the Thuringia Saigerhütten came to an end. In Saxony in 1471 Ernst and Albrecht von Sachsen granted the merchant Nickel Tyle and a Saiger trading company the privilege to build a Saigerhütte in Chemnitz . In the 1490s Jakob Fugger established the Sauchter in Schwaz in Tyrol (from where almost half of all European silver soon came, the lead came from Tarrenz - Gurgltal ) and in the Fuggerau in Carinthia (lead from Bleiberg ), shortly afterwards also in Neusohl in Upper Hungary ( today Slovakian Banská Bystrica ). From 1538 the Saigerhütte Grünthal , founded by the Annaberg miner Hans Leonhardt, worked , which in the following years developed into an important industrial complex and the center of copper processing in Saxony.
literature
- H. Georgii Agricole vom Bergkwerck / the eleven [eleventh] book. Frankfurt 1580, pp. 419-465 ( digitized version ) - The Saiger process for silver separation and copper extraction according to Georgius Agricola
- Lothar Suhling : The Seigerhütten process. The technology of copper seizing according to the early metallurgical literature. Riederer, Stuttgart 1976.
Web links
Individual evidence
- ^ Walter Möllenberg : Document book on the history of the Mansfeld Saiger trade , Halle (Saale) 1915, pp. 179-185.
- ↑ a b c Hanns-Heinz Kasper : From the Saigerhütte to the Kupferhammer Grünthal 1537–1873 - From the 450-year history of a metallurgical company in Olbernhau-Grünthal. Publisher: Saigerhüttenverein eV Olbernhau-Grünthal, Druckerei Olbernhau GmbH, 1994, pp. 10-11.
- ↑ Hanns-Heinz Kasper: From the Saigerhütte to the Kupferhammer Grünthal ... p. 14.
- ↑ See Hanns-Heinz Kasper: The Saigerhütte Grünthal. Care and maintenance of a metallurgical monument from the time of Georgius Agricola. In: Sächsische Heimatblätter Heft 2/1994, pp. 87-91, ISSN 0486-8234
- ↑ See Peter Lange: Saigerhütten in Thuringia. In: Copper Silver Steel - Contributions to the history of metallurgy. Published by the museums of the city of Olbernhau, Olbernhau 1988, pp. 15–17.
- ↑ See Peter Lange: Saigerhütten in Thuringia. ... p. 29.
- ↑ See Andrea Kramarczyk: The Kupfersaigerhütte of Ulrich Schütz in Chemnitz. Company history, documentation, perspectives of a ground monument. (PDF; 2.2 MB), (12th Agricola conversation of the Agricola Research Center Chemnitz on June 5, 2003), In: Agricola circulars of the Agricola Research Center Chemnitz , circular 2003, pp. 3-19. (accessed on March 13, 2012).