Iron Ores

                               Iron Ores Iron ore is a type of minreral and rock from which metallic iron is extracted economically. This ore is normally rich in iron oxides and vary in color from dark grey, bright yellow and deep purple to rusty red. The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite (FeO(OH)), limonite (FeO(OH).n(H2O)) or siderite (FeCO3). Different types of iron ores are shown in Fig 1 Fig 1 Types of Iron ores The main ores of iron are hematite (70% iron) and magnetite (72% iron). Ores carrying very high quantities of hematite or magnetite (greater than 62% of Fe) are known as “natural ore” or “direct shipping ore”, meaning they can be fed directly into iron making furnaces. Taconite is low grade silica rich iron ore containing up to 30% magnetite and hematite. This deposit can be processed to produce a concentrate of Fe around 65%. This ore is a major source of iron in USA, Canada and China. Magnetite is also known as magnetic iron ore because it is easily attracted by a magnet. It is a heavy black mineral with metallic luster. Hematite is a steel-gray to iron- black colored mineral which is as hard as magnetite (Moh’s scale hardness is 5.5 to 6.5) but slightly less heavy (usually specific gravity varies from 5.0 to 5.3). It has also a metallic luster. The three primary sources of iron ore are banded iron formations, magmatic magnetite ore deposits, and hematite ore. Banded iron formations (BIF) – These are fine grained metamorphosed sedimentary rocks composed predominantly of magnetite and silica (as quartz). Most of the iron ore is extracted from banded iron formations, the geological structures laid down mostly between 3 and 1.2 billion years ago. Blue...