Slags from the iron and steel industries are sometimes erroneously classified, and often looked upon, as industrial waste materials. In fact, these co-products are valuable and extremely versatile construction materials. The need for maximum utilization for economic and environmental reasons has led to rapid development of slag utilization.
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Slag can help grass grow by adding micronutrients to the earth, by neutralizing soil acidity, by conditioning the grass and helping to retain moisture.
Slag has been proven to be a valuable replacement for agricultural lime. It can help increase crop yield, and improve soil texture by breaking down clay-like soil.
Slag can be used as a permeable reactive barrier to remove contaminants from water. When used as a trickling filter media in water purification, slag particles provide increased surface area and a high degree of void, both essential to efficient filtering. Slag is also a potential phosphorus removal media for waters at fish farms.
The Japanese implant certain species of oysters with small slag particles to stimulate the growth of pearls. Chickens need to swallow gravel as grit for their two-stage digestive process. But it has been discovered that slag’s angular surfaces do a better job than regular gravel and produce fatter chicken in less time. When cattle are transported to market the floor of the freight cars are covered with slag sand. It’s economical, absorbent, comfortable, and even acts as an odor neutralizer. Slag can also be used for dog runs for the same reasons.
Slag may assist in attaining LEED credits by the Green Building Council for new construction because of its recycled/renewable resource content.
In areas where iron and steel are manufactured, an agricultural blast-furnace slag product, including ladle metallurgical furnace slag, may be available as an economical alternative to agricultural limestone or dolomite and as a better source of micro nutrients. According to studies as far back as 1927 by Penn State University, Ohio State University, U.S. Department of Agriculture, Auburn University, and Canadian research, Ag-Slag applications have been equivalent to limestone and dolomite in increasing crop yields at equal levels of fineness. Both blast furnace and steel slag have chemistries that make them suitable as liming materials. Slag serves not only as a liming agent, neutralizing soil acids, but it also contains important micro-nutrients often lacking in soils. Agricultural slag corrects soil acidity basically in the same manner as limestone. Calcium carbonate equivalence (CCE) ratings can be directly compared.