ZINC (Part three)

by Darren
Zinc part 3

This is the last in a trilogy of short articles on the history, production and usage of zinc sheeting, presented by Rheinzink. This private company was founded in 1966 and is recognised today as a world leader in the manufacturing of titanium zinc roofing, cladding and roof drainage systems.


Recycling, the environment and sustainability

The deposits of zinc ore in existence are only known as far as they have been investigated for mining in the near future. Other deposits are explored regularly, changing the limits of availability, also depending on the technology used and the achievable price.

The zinc content of the reserves of ore probably considered to exist in 1999 was approximately 200-million tons, of which about half comes from Australia, China, the USA and Canada. The total reserves of zinc identified in terms of the metal content of the deposits are put at approximately 1,9 billion tons in total throughout the world.

In addition, some 30% of the zinc used in the world today is recovered by recycling materials containing zinc. This share is already exceeded in Germany and is set to rise worldwide in coming years.

Applications and recycling today

Zinc is mainly used in the form of sheets and other semi-finished products, in particular in the building industry. In alloys it is mostly combined with copper as brass and with aluminium to make die-cast parts – about one third of the total zinc production. To protect steel parts from corrosion takes about half of the total zinc production, and in the chemical industry it appears as zinc oxide and zinc dust.

Zinc sheets are used in construction, not only to protect steel parts from corrosion, but also for roofs, facades and roof drainage. At the end of their service life they can be melted down and reused as secondary zinc in alloys, for galvanisation or in the chemical industry.

The level of recycling is often described by setting the quantity of recycled material against the new material produced over the same period of time. However, this definition is misleading. If we set the old waste occurring today (new scrap is not included here as it is channelled directly back into the production process) against the total production at the time when this material was produced, it will then become clear that zinc is used, but barely consumed.

The quantity of old waste more or less corresponds to the production volume at the time of manufacturing of the products recycled as old scrap. If we consider the different volumes and usage periods occurring for the individual applications, we can assume an average of 30 years. The recycling rate defined for the zinc used by the German building industry is virtually 100%.

The recycling of metals is important for a number of reasons. Firstly it reduces the quantity of materials going to landfill. In the case of valuable metals’ such as zinc, practically nothing is left over as waste from the original metal at the end of its life. All scrap is submitted for processing and recycling via established channels. These metals can also be recycled an infinite number of times.

The benefits of zinc sheeting

The benefits of zinc sheeting and cladding are legion, and the inherent resilience of zinc is one of its most important assets. Properly installed zinc roofs have been known to last for over 100 years, and this impressive lifespan is due the ability of zinc to heal itself.

If iron is left out in the rain or in contact with salt, the chemical reaction will form ferrous oxide or rust, which corrodes the iron. Zinc, on the other hand, develops a protective layer called zinc hydroxyl-carbonate. Once formed, that layer blocks moisture and chemicals from penetrating to the zinc beneath and, if scratched, the hydroxyl-carbonate will reform over time.

Protecting the climate with a sustainable product
The low toxicity of zinc sheeting is a major plus for the environment. Zinc is nearly 100% recyclable. In addition, the water run-off from zinc roofing doesn’t pick up additional chemicals that will taint the soil and groundwater supply.
Since most zinc sheeting can be recycled, it further lowers the energy cost of manufacturing. Already, zinc mining and production take a quarter of the energy needed for aluminium and half of that for copper. Moreover, recycling zinc demands less than 20% of the original input.
There are not many other materials with such a favourable environmental lifecycle assessment as Rheinzink sheeting. The amount of energy required to obtain and process zinc is extremely low, and emissions are kept to a minimum thanks to state-of-the-art production facilities, in addition to which all Rheinzink products can be recycled 100%.

Nowadays a third of every Rheinzink product is made up of recycled zinc once used for construction. Following a comprehensive evaluation of its entire lifecycle, the material was certified as an environmentally-friendly building product by the independent organisation Institute of Construction and Environment (Institut Bauen und Umwelt eV- IBU) in 1999. Furthermore, Rheinzink is certified by BREEAM and LEED.

The versatility of Rheinzink is appreciated by architects all over the world, as international architects turn to Rheinzink to give perfect expression to their designs. For them the great attraction of this material is the enormous variety it offers: from avant-garde to more traditional, roofs and facades made of Rheinzink always represent a high-quality functional solution that won’t date.

And this is further enhanced by a wide range of accessories. Whether cladding for dormers, gables or chimneys, verges, soffits or garage doors, Rheinzink accessories will blend with any architectural style and materials, and it is guaranteed to be the highlight of every building.

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