Scrap Metal Recycling: Scrap Metal Recycling Is Not Very Glamorous, but It Might Help Save the Planet
Childress, Vincent W., The Technology Teacher
If one thinks that an understanding of scrap metal recycling is not important, consider the following: Recycling is a 65 billion dollar-per-year industry. Scrap metal recycling saves 74% or more of the energy it takes to smelt metal from ore (Institute of Scrap Recycling Industries, 2007). That represents a significant reduction in greenhouse gas emissions. Scrap metal recycling (and other forms of recycling) is not very glamorous, but it might help save the planet. Recycling has been a significant industry in the United States for more than 200 years. For primitive cultures in the copper, bronze, and iron ages, recycling existing metal was much less labor-intensive than mining and smelting metal from ore. That is still the case today.
Iron ore is a naturally occurring element found in the earth's crust. It is mined by digging it out of large pits with large excavating equipment. In its natural state, iron ore is a metallic-looking rock that usually has other types of nonmetallic rock clinging to it. When ore is fired or heated to its melting point in a blast furnace, a great deal of air pollution is created by the burning of coal. Refining ore into metal is called smelting. It takes significantly larger volumes of coal to smelt ore than it does to simply melt down recycled iron and steel. Thus, air pollution can be reduced by recycling metals.
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While iron ore is plentiful in the United States and many countries around the world, the process of smelting iron ore into steel is energy-intensive. Iron ore is placed into a huge container that can hold about 20 tons or more of ore.
A fire melts the ore so that the liquid iron separates from the rocky, non-iron materials. Coke is used to more efficiently heat the ore in the smelting process. To understand what coke is, consider charcoal. Common charcoal is the solid char leftover when wood is burned. Charcoal is useful because it ignites quickly and burns hot. Coke is like charcoal; it is what is left after partially burning coal It has the same advantages of charcoal but has much more energy. Steel is most effectively refined when coke is used in blast furnaces. So, to fully smelt iron and produce steel with it, the manufacturer must fire coal to make coke, and then it must fire the coke to make steel. This is an energy-intensive process, and in the process, tons of greenhouse gases and toxic elements and compounds are released into the atmosphere annually.
Consumers are aware of some recyclable materials but are less familiar with others. Consumers are familiar with the recycling of aluminum cans, paper, and some plastics because many communities encourage consumer recycling through local programs. It is not unusual for some forms of glass and steel cans to be accepted in consumer-level recycling programs. However, entire automobiles can be recycled for steel and aluminum and, in some cases, glass and plastics. Building demolitions also produce structural steel for recycling. Consumers are less aware of automobile recycling and structural steel recycling. Lead-acid automobile batteries are also recycled, as are the components of electronic hardware. The Institute of Scrap Recycling Industries (2007) reports the following statistics on recycling volumes in the United States annually. (Table 1.)
Land use is a big issue around the world. Landfills are filling to capacity at alarming rates, and consumers do not realize the extent to which municipal waste is dumped directly into the oceans. Equally alarming is the rate at which municipal waste is being incinerated, thus adding to the air pollution problem and global warming. The Environmental Protection Agency (2007) estimates that in 2005, 79 million tons of waste was recycled--an increase of 64 million tons since 1980. This figure does not include automobile and structural steel recycling. …