Tinplate
Tinplate is a thin cold-rolled steel sheet , the surface of which is coated with tin . Sheet metal thicknesses of 0.1 to 0.5 mm are currently common. The tin used primarily for corrosion protection .
Up to the middle of the 20th century, hot-dip tinning, in which the tin was applied in a molten state, was common. With today's electrolytic tin plating, the coating has not only become more uniform but also much thinner, which saves both raw materials and costs.
history
The technical processes have evolved over the centuries. The manufacturing process changed from hot rolling to cold rolling and the tinning process from hot-dip tinning to electrolytic tinning.
In the 17th / 18th In the 19th century, tin-makers made sheet metal in smaller plates, pickled it in rye bran and tinned it by dipping it in liquid tin.
In the 18th / 19th In the 19th century, tinplate was initially only produced industrially in large quantities in England, as technical progress was enormous in the motherland of the industrial revolution. The fat kettle was introduced here as early as 1745 and pickled with dilute hydrochloric acid from 1806.
Since the 19th century the history of the tinplate production is closely linked to the history of tin linked. With the developments of Nicolas Appert , who patented the preservation of food through heat sterilization in 1810 , and the method of the Englishmen Peter Durant and Augustus de Heine for storing food in light cans , the demand for tinplate increased enormously.
The cold rolling process has existed since 1816 and the process of forming tinplate by annealing in annealing furnaces since 1829. The thickness of the sheet has been steadily reduced since the 18th century until today. The first electrolytic strip tinning line was put into operation in 1934 - this also made a much thinner coating possible.
Tinplate in Germany
The processing of steel into tinplate was an important economic factor in the 19th century, especially in the Rhenish areas, and in the 20th century in today's Rhineland-Palatinate. Today tinplate only plays a minor role in Germany.
18th century
In the early 18th century, at the beginning of the industrial revolution, steel production was not yet centered on the Ruhr area to the extent that it was later to be. In the areas on the Rhine , especially the Neuwied basin east of Koblenz , there were some steel processing companies such as the Bendorf Sayn ironworks ( Bendorfer Hütten , Sayner Hütte ) or the Rasselstein , which was built in 1784 by the entrepreneur Carl Wilhelm Remy the Prince Alexander Graf zu Wied was bought. In 1769 the first German sheet steel was rolled in Rasselstein.
19th century
In 1824, the Remy family succeeded in opening the first puddle steel plant in their Rasselstein plant. It is also thanks to the technical developments at the production facility that the first German railway line from Nuremberg to Fürth could be used in 1835 . The rails for this also came from Rasselstein. In the middle of the 19th century, the Englishman John Player began building the Albion ironworks and producing tinplate. After closing down the business in 1856, the Remy family started tinplate production with the Rasselsteiner plant.
In addition to the Rasselstein plant, other companies in Germany such as Dillinger Hütte produced tinplate. In the 1860s, a "tinplate sales office" was founded in Germany, in which by merging to form a cartel, competition within Germany was to be avoided and a better position compared to Great Britain achieved.
20th century
With the coal mining in the Ruhr region also occurred in the other on the Rhine-lying areas around the region Koblenz to a structural change , the majority of steel production in which, in the present state of North Rhine-Westphalia shifted. In the 20th century, tinplate was still produced at various locations in Germany, for example in Wissen and Andernach in what is now Rhineland-Palatinate, where the development of an electrolytic tinning process for tinplate led to a revolution in the manufacturing process in 1934.
After the Second World War , the only tinplate manufacturers in Germany are only based in Rhineland-Palatinate. With an annual turnover of 7,292 million euros in 2010, the metal industry is the third largest industrial sector in Rhineland-Palatinate in terms of turnover. The tinplate production by ThyssenKrupp Rasselstein is one of the largest employers in the Koblenz area.
Technical aspects
Corrosion protection
A layer of approx. 0.3 µm tin, which corresponds to approx. 2 g / m², is sufficient to protect the steel from corrosion by sealing . Zinc and chromium are electrochemically less noble than steel. Unlike tin, they therefore offer additional electrochemical protection against corrosion. However, zinc is unstable to acids and acidic foods, and chromium compounds are poisonous. Tin compounds are toxic to a small extent, but if the protective tin layer is damaged and a local element is created , the less noble iron corrodes first and harmless iron salts are formed. Therefore, tinplate is also suitable for storing watery foods in cans. However, tin ions can be released when exposed to air. This is why tinplate cans are often additionally lacquered or foil-coated on the inside.
use
Around 90 percent of the tinplate produced in Germany is used to manufacture packaging. This is why one also speaks of packaging steel. The main areas of application of packaging steel are in the following four areas:
- Tin cans for food and pet food (approx. 44 percent)
- Packaging for chemical-technical products and spray cans for aerosols (approx. 22 percent)
- Closures: lids and crown caps (approx. 18 percent)
- Beverage cans (approx. 16 percent).
In addition, tinplate is used, for example, for the production of (now rather rare) tin toys and jewelry boxes .
Further areas of application for tinplate are connections, battery contacts, battery housings and shielding housings in electrical engineering and electronics, because tinplate can be soldered with acid-free fluxes .
recycling
The recycling rate for tinplate in Germany was 93.3 percent in 2014. This is the highest recycling rate among packaging materials. However, recycling causes problems: layers of paint and material residues are a problem and the tin can only be recovered if the tinplate scrap is aluminum-free. The tin is removed electrolytically in hot sodium hydroxide solution.
After the waste incineration z. For example, tinplate cans recovered by a magnetic separator do not contain any organic residues, but also no metallic tin: the expensive tin is also lost here. These cans can be used (melted down) in steel production. The high sulfur content due to waste incineration does not allow for equivalent reuse.
market
The tinplate market is a typical niche market . It suffers from strong fluctuations in raw material and energy costs and at times from overcapacities.
literature
- Klaus Peters: 200 years of Rasselstein, a contribution to the history of fine sheet metal. Steel and rolling mills Rasselstein / Andernach AG, 1960.
- The iron and steel industry in the Wieder basin. Development history overview using the example of the Concordia Hütte, the Sayner Hütte and the Rasselstein. Association of German Ironworkers, 1987.
- A piece of German industrial history. 225 years of Rasselstein. From Count zu Wied to Remys, the development led to a strong “shareholder family”, today the “pearl” of the Thyssen Group. In: stadtmagazin - Life in Neuwied. Volume 12, 1985, No. 9, pp. 10-15.
Web links
Individual evidence
- ↑ Reinhold Reith : Recycling - Material Flows in History . In: Cross sections 8: Environmental history. Fields of work, research approaches, perspectives . Edited by Sylvia Hahn, Reinhold Reith. Oldenbourg, Munich 2001. Quote: "In 1934, electrolytic tinning reduced the amount of tin per square meter by two thirds".
- ↑ The history of the former tinplate mill (rolling mill) Wissen , online on the Internet: February 5, 2013.
- ↑ http://www.stahl-online.de/index.php/weissblech-meistrecycelter-verpackungswerkstoff/
- ↑ N. Kopytziok: Handbook for environmental and waste advice, July 2005, Section 2.11: Is aluminum / tinplate recycling worthwhile? (PDF, page 2).