Construction has a profound impact on our natural environment. In North America, the built-up environment accounts for approximately one third of the greenhouse gas (GHG) emissions, as well as energy, water and materials consumption. Given the increased awareness of “green” construction, steel is the material of choice because of its major recycled content and recyclability attributes.
Steel is the world's most recycled material, and in North America, over 70 million tonnes of steel are recycled or exported for recycling annually. This is done for both economic and environmental reasons. It is always economical to recycle steel. Even though two out of every three kilograms of new steel are produced from “old” steel, the fact that buildings, appliances, bridges and other infrastructure products have such long service lives, makes it necessary to continue to mine some virgin ore to supplement the production of new steel.
Once iron ore is extracted and refined into steel, its life never ends. This makes steel an ideal material to deploy in sustainable strategies for the construction industry. Today’s steel is produced using two technologies, both of which require “old” steel to make “new” steel. The combination of these technologies gives Canadian steel mills the flexibility to produce a variety of steel grades for a wide range of product applications.
From a car to a bridge to a culvert and back to a car.
Steel possesses a unique material property unrivalled by other materials in that it can be recycled both up and down the product value chain. Open loop recycling allows, for example, an old car to be melted down to produce a soup can, and then, as the new soup can is recycled, it is re-melted to produce a new appliance, a structural beam used in a bridge or building, or corrugated steel drainage products like culverts.
Unlike competing materials, recycling in the steel industry is second nature. The North American steel industry has been recovering and recycling steel scrap for over 150 years through over 1,800 scrap processors and a network of 12,000 auto dismantlers across the Continent. As a result of the large quantities of “old” steel supplied to the steel manufacturers, the steel industry is Canada’s largest steel recycler consuming over 8 million tonnes of steel scrap every year.
Recycled content of steel construction products is very high.
Canadian steel producers use both Electric Arc Furnace (EAF) and Basic Oxygen Furnace (BOF) technologies interchangeably, to supply construction market end uses.
The scrap-based EAF technology uses close to 100 percent steel scrap as its feedstock. EAF steels are used in construction products such as culverts and other drainage products, underground water detention systems, commercial roofing and cladding, steel studs, decking, and floor joists where the major required material characteristic is strength.
The traditional BOF technology uses typically 25 percent steel scrap (“old” steel) to make new steels. Steels manufactured by the BOF method are used to produce products where formability is a key material requirement. These products include automotive outer body panels, automotive axle shafts, hydro formed tube applications, and exterior panels for appliances, residential door skins, and packaging, as used in soup cans as well as construction products.
[ Source: Canadian Steel Pipe Institute, Technical Bulletins, cspi.ca ]