Galvanization is a method of applying a protective zinc coating to steel or iron for industrial use, in order to prevent rusting. Zinc, a metallic element can withstand much more than steel or iron, and thus lasts much longer as it acts as a physical barrier against rust. The actual procedure is where fabricated steel, structural steel and various other steel parts are dipped into a large kettle of molten zinc and is called hot-dip galvanizing.
While zinc is a natural substance and is necessary for human health, too much of element can be harmful to human health. Most food, air, water and soil contain certain amounts of zinc, but due to industrial activities, the level of zinc is rising at an unnatural rate. Certain areas around industrial sources are considered toxic due to the high amount of zinc in the drinking water. Health effects for people can include stomach cramps, skin irritation, nausea and vomiting. Extreme levels can damage internal organs and cause respiratory disorders. Acute work-place exposure to high-levels of zinc can lead to flu-like symptoms for people that are especially sensitive.
With the increase of zinc effecting people, it is also causing an effect on the environment. Water is often the first to become polluted where industrial plants do not purify their waste water to a satisfactory level. This may be a cause in the rise of acid levels within water – effecting local flora and fauna. Certain fish accrue high levels of zinc in their bodies which is then passed on to other animals and humans when the fish is consumed.
Zinc can also be found in soil. When farmers grow their crops, the zinc is then leeched into the food supply and again moves further up the food chain through consumption.
Zinc is, however a step up from other chemicals that are used as rust inhibitors. Lead is often contained in red pigment used in paint that is then used as a rust inhibitor and is commonly used in industrial settings much like zinc. To be considered lead free during the galvanizing process, there must be less that .01% lead used in the hot dip.
While an increase in zinc can be harmful, we also have to look at the benefits. The use of Zinc can add to sustainable development because of its longevity in protection, its recyclability and when cleaned up and filtered properly, it’s minimal environmental impact. Galvanizing provides 50+ years of maintenance-free rust and corrosion protection and therefore it doesn’t require any additional energy or produce any additional waste. The biggest issue with hot-dip galvanizing seems to be the clean-up efforts. As of now, the American Galvanizers Association (AGA) is working together with the International Zinc Association (IZA) to contribute to Leadership in Energy and Environmental Design (LEED) points.
With the reduction in use of lead, the main environmental issue with galvanization seems to be the poor clean-up efforts in some industrial areas. A major concern is the purification of waste water and once that is managed more successfully, galvanization can truly be considered a sustainable and eco-friendly process.
References
* American Galvanizers Association. (2011). Retrieved December 5, 2011, from http://www.galvanizeit.org/
* Zinc - ZN (1998- 2011). Retrieved December 5, 2011, from http://www.lenntech.com/periodic/elements/zn.htm