Zinc: the perfect recyclable material 

Zinc: the perfect recyclable material 

The most common application of zinc is to protect steel from corrosion by hot-dip galvanising. This zinc-steel combination has significant economic benefits in terms of lifecycle costs.

Thanks to diminishing levels of sulphur dioxide (SO2) and the associated improvements in air quality in many industrialised countries, zinc coatings now provide even longer protection for steel.

“Steel is one of the most widely used materials on the planet. Thanks to zinc, steel’s durability can be prolonged,” says Simon Norton, the International Zinc Association (IZA) Africa’s executive director.

Both steel and zinc are 100% recyclable indefinitely, without the loss of chemical or physical properties. In fact, steel is the most recycled material in the world, with virtually all structural steel reclaimed for repossessing and nearly 94% of structural shapes being built from recycled steel. The reclamation rate for zinc, meanwhile, is more than 80%, so the majority of zinc available for recycling is, indeed, recycled.

At present, about 70% of the zinc produced originates from mined ores, while 30% comes from recycled or secondary zinc. The level of recycling is increasing in step with progress in zinc production and zinc recycling technologies. Zinc is recycled at all stages of production and use, from the production of galvanised steel sheet to scrap generated during manufacturing and installation processes, as well as from products at their end-of-life.

The life of zinc-containing products is variable, ranging from 10 to 15 years for cars or household appliances to over 100 years for zinc sheets used for roofing. Street-lighting poles made from zinc-coated steel can remain in service for 50 years or even much longer, while transmission towers can endure for over 70 years.

“All these products tend to be replaced due to obsolescence, not because the zinc has ceased to protect the underlying steel. For example, zinc-coated steel poles placed in the Australian outback a hundred years ago are still in excellent condition,” reports Norton.

The presence of zinc coating on steel does not restrict steel’s recyclability and all types of zinc-coated products are recyclable. Zinc-coated steel is recycled along with other steel scraps during the steel production process, during which the zinc volatilises and is then recovered. The supply of zinc-coated steel scrap is expected to double over the next five years, as more zinc-coated products enter the recycling stream.

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