Pub. 5 2015 Issue 1

9 MINING FOCUS usually not concentrated except in meteorites. Iron is most of - ten found in the form of iron oxide, and the minerals with the highest iron content are near the earth’s surface. Most of us take iron for granted, but as a society we de- pend heavily on it. Although iron is heavy and can rust if there is moisture in the air, it is a useful construction material be- cause of its strength and toughness. Rust can be avoided by either placing some kind of protective cover over the iron, or embedding iron within another object so it will not be exposed. Pure iron is a white, bright metal that is shiny and can be hammered or rolled into a thin sheet or stretched into a wire: • Because it can be formed into a sheet, it is called malleable. • Because it can be stretched into wire, it is called ductile. Iron by itself is soft. Its atoms are arranged in a regular pattern, making it easy for layers to slide on each other. If you were to see the atoms they would look like little balls ar- ranged in rows and columns. Iron is generally too soft to be useful unless it has been altered in some way. Iron is used to make steel, for example, by blowing oxygen into molten iron and removing carbon. The oxygen and carbon react, forming carbon monoxide and carbon dioxide, and escape from the molten metal. Vanadium and chromium are also sometimes added in order to create alloys with specific useful properties. Oddly enough, even though iron is soft, it can also be categorized as being hard. It is a transition metal, a term that refers to the way in which the d-shell of electrons is filled. What that means in practical terms is that the bonds between at- oms are strong. Its melting points and boiling points are both high, and it is also extremely dense on the atomic level. For example, let’s compare the density of iron to sodium. The den - sity of sodium is only 0.97 grams per cubic centimeter, which is less than the density of water. That is why sodium floats. Iron, on the other hand, has a density of 7.9 grams per cubic centimeter — a density more than eight times that of sodium. Iron can be worked easily and inexpensively. It is often used to reinforce concrete, and it is also used to make fasten- ers such as nails and screws. Iron’s primary competitors are plastic and aluminum: • Plastic is a less expensive alternative for products that don’t have to be as strong or durable. • Aluminum is sometimes used in applications such as the construction of airplanes, where its lighter weight gives it an advantage over iron. The real advantage of iron, however, is its use in alloys. An alloy is a combination of two or more metals. The result- ing properties of the alloy are a combination of the metals used. However, both metals still have their original chemical properties, and can be separated by melting the alloy. Alloys differ from compounds in that compounds undergo a chemical reaction and are characterized by chemically bonded ele- ments; electrons are shared or transferred, and as a result, it is impossible to physically separate a compound once it has been made. Iron and its resulting steel alloys are indispensable building materials that exist only because of today’s safe and envi - ronmentally responsible mining industry. As scientists and engineers continue to learn more about iron and its alloys, these mined materials will continue to advance society and our way of life for centuries to come. X Iron became most useful after scientists began to understand the chem- istry involved in the process of making it, and especially the role of carbon in making iron hard. Recycling industrial-related scrap metal is one of the things we do best! www.umw.com | 801.364.5679 Utah Metal Works, Inc.