The Green Thumb
Let's Get More Familiar (Part One)
market share, there are many aspects of LGMF worthy of discussion from both an industry and environmental perspective. We'll begin with a look at the resources required for the steel/LGMF manufacturing process.
Caveat emptorOne of the most attractive characteristics of LGMF is the recyclability (100 percent) of all steel products and the recycled content (25 to 100 percent) of LGMF. In reality, the recycled content of LGMF is very much dependent upon the method employed in its manufacture: either the traditional basic oxygen furnace method or the modern Electric Arc Furnace method. In part two, we'll examine both of these methods in depth.
The North American steel industry claims to recycle 64 percent of all steel products. In 2002, this translated to 70 million-plus tons of steel recycled here in North America or exported for recycling. This includes such post-consumer products as: cans, appliances, automobiles (there are 12,000 auto dismantlers in North America) and construction materials.
For more than 150 years, steel has been recycled-its magnetic properties making it easy and efficient to "cull-out" of the solid waste stream. Currently, there are about 1,800 scrap processors in North America-many in business since the 19th century. Steel remains the most recycled material on the planet. More steel is recycled annually than all glass, paper, plastic and aluminum combined.
There's good reason for all this effort at recycling and it's not altruistic-it simply makes good economic sense since it is cheaper to use recycled steel than make new steel from virgin materials. However, whether the finished steel product contains 30 or 100 percent recycled content, the quality and strength of the finished steel product is in no way diminished. The high standards and precision by what steel is made guarantees its quality and status as having the highest strength-to-weight ratio of any building material. Steel's economic good sense for recycling has the advantage of conserving non-renewable natural resources and conserves landfill space. Since steel has a long lifecycle, it will always be necessary to mine its essential ingredients:
• Iron ore • Limestone
• Coal • Zinc
Iron ore and limestone cause the worst eco-disruption since these minerals are obtained primarily from open-pit and strip mines on the earth's surface. Such surface mining completely disrupts and destroys valuable ecosystems, and leaches large quantities of metals and minerals into local and regional water supplies/sources. In the United States, environmental controls and regulation have limited this ongoing damage but in other regions where iron ore is mined, such as South America, such stringent controls are not in place and the resulting damage to Mother Earth can be devastating. The U.S. Environmental Protection Agency estimates that surface mining operations cause 48,000 tons per square mile of surface erosion annually.
Native wealthCoal for steel making comes primarily from underground mines in Appalachia (western coal is unsuitable for steel making because it lacks the required metallurgical properties needed). Since the 1890s, the majority of iron ore used to make steel comes from the Mesabi Range, in northern Minnesota. Though there is estimated to be an abundant supply that will last for several centuries, the quality of the ore is in decline. This has allowed iron ore imports from South America (Venezuela and Brazil, specifically) to gain a foothold in the North American market. Limestone is also in abundant supply in North America and is typically quarried near steel making facilities.
Zinc for galvanizing is mined in a variety of regions in North America. Though zinc supplies are plentiful, the byproducts of the "smelting" process to obtain zinc for galvanizing from zinc ore is environmentally controversial. Wastewater from zinc smelting sites contain heavy metals, such as Cadmium, chlorinated compounds and toxic organics. Many former zinc smelting sites are now "Superfund" cleanup sites. About one-third of the zinc consumed in the United States is produced domestically-the balance comes from Mexico, Canada and other countries. Of the one-third produced here in the U.S., about a third or 33 percent is reclaimed/recycled. Galvanized steel is melted whereby the zinc evaporates and is recaptured for reuse.
There are tangible and significant positive results from recycling steel. Consider that each ton of recycled steel saves:
• 2,500 pounds of iron ore
• 1,400 pounds of coal
• 120 pounds of limestone
From a lifecycle perspective, energy savings due to LGMF's airtight capabilities for a building envelope, long structural life and the conservation of iron ore resources save the electrical energy equivalent to powering 18 million (plus or minus 20 percent) American homes. On the job site, LGMF represents only about 2 percent of the solid wastes produced-primarily due to its recyclability and ease of separation from other materials, such as wood that generates about 20 percent of the solid waste at a construction site.
All LGMF, no matter what the manufacturing method used, contains a minimum of 25 percent recycled steel content and as much as 100 percent. Whatever the recycled content percentage, it is always 100 percent recyclable. Steel made by the traditional Basic Oxygen Furnace method typically contains about 30 percent recycled content, whereas steel made by the Electric Arc Furnace method is made from up to 100 percent recycled content. The 64-percent recycling rate used by the steel industry includes "home scraps"-steel scraps that never leave the mill. Such scraps are not considered "recycled" and/or "recovered" materials by most industries.
As well, steel scrap collected domestically and exported is included in this percentage. This steel does not return as recycled content in products manufactured in the United States. For these reasons, the overall realistic recycled content of domestically produced steel is about 46 percent.
The advent and success of the U.S. Green Building Council's LEED green building certification/rating system has increased the appeal and use of LGMF. Under LEED v.2.1, points under credits 4.1 and 4.2 are earned while incorporating LGMF in a building's design since the steel used in LGMF-whether manufactured by the BOF method or the EAF method, exceeds the 5- and 10-percent goals set forth in the LEED criteria for these credits.
In part two, we'll examine the steel manufacturing process overall and the process for manufacturing LGMF in particular.