Iron Ore: Analysis Ajay Chauhan 4/29/2012 Contents Introduction ............................................................................................................................................ 4 Iron Ore ................................................................................................................................................... 5 Uses ......................................................................................................................................................... 7 Commercial Grades and Specification .................................................................................................... 8 Ore Characterization ............................................................................................................................. 10 Haematite ......................................................................................................................................... 10 Magnetite .......................................................................................................................................... 10 Goethite and Limonite ...................................................................................................................... 11 Siderites ............................................................................................................................................ 11 Iron Ore Deposits .................................................................................................................................. 12 Bedded Sedimentary Deposits .......................................................................................................... 12 Sedimentary iron ore deposits of siderite and limonitic composition ............................................. 13 Laterite ores derived from the sub-aerial alterations ...................................................................... 14 Igneous Activity ................................................................................................................................. 14 Surface and Near-Surface Weathering ............................................................................................. 14 Iron Mining Processes ........................................................................................................................... 15 Drilling ............................................................................................................................................... 15 Blasting .............................................................................................................................................. 16 Opti Blast Technology ................................................................................................................... 18 Split Charge blasting techniques with Air Decking by Gas Bags ................................................... 18 Electric Initiation ............................................................................................................................... 19 Ripper - an environment friendly alternative for Drilling & Blasting ................................................ 19 Hydraulic Hammer/ Rock Breaker – An environment friendly alternative to Secondary Boulder Blasting .............................................................................................................................................. 20 Excavation ......................................................................................................................................... 20 Haulage and Transportation System ................................................................................................. 22 Beneficiation Methods ...................................................................................................................... 23 Milling ........................................................................................................................................... 24 Magnetic Separation ..................................................................................................................... 25 Flotation ........................................................................................................................................ 26 Gravity Concentration ................................................................................................................... 27 Thickening/Filtering ...................................................................................................................... 28 Agglomeration .............................................................................................................................. 28 Smelting ................................................................................................................................................ 30 Trace elements .................................................................................................................................. 30 Process .............................................................................................................................................. 30 Roasting......................................................................................................................................... 31 Reduction ...................................................................................................................................... 31 Fluxes ................................................................................................................................................ 31 Blast Furnace ..................................................................................................................................... 31 Electric Arc Furnace .......................................................................................................................... 34 Bloomery ........................................................................................................................................... 36 Reverberatory Furnace ..................................................................................................................... 37 2012 Iron Ore Market Outlook ............................................................................................................. 38 Positive outlook for iron ore ............................................................................................................. 39 Substitutes and Alternative Sources ................................................................................................. 39 Introduction Iron is the second most abundant metallic element in the Earth’s crust and accounts for 5.6% of the lithosphere. The principal minerals of iron are the oxides (haematite and magnetite), hydroxide (limonite and goethite), carbonate (siderite) and sulphide (pyrite). Iron, like most metals, is found in the Earth's crust only in the form of an ore, i.e., combined with other elements such as oxygen or sulphur. Haematite and magnetite are the two important iron ores from which iron is extracted. Of these, haematite is considered to be superior owing to its high grade. It is the basic raw material for iron and steel industry. Steel is an alloy that consists mostly of iron and has carbon content between 0.2% and 2.1% by weight, depending on the grade. Iron is extracted from ore by removing oxygen and combining the ore with a preferred chemical partner such as carbon. This process is known as smelting. Since the oxidation rate itself increases rapidly beyond 800 °C, it is important that smelting take place in a low oxygen environment. Smelting results in an alloy (pig iron) containing too much carbon to be called steel. The excess carbon and other impurities are removed in a subsequent step. Other materials are often added to the iron/carbon mixture to produce steel with desired properties. Nickel and manganese in steel add to its tensile strength and make austenite more chemically stable, chromium increases hardness and melting temperature and vanadium also increases hardness while reducing the effects of metal fatigue. To prevent corrosion, at least 11% chromium is added to steel so that a hard oxide forms on the metal surface; this is known as stainless steel. Tungsten interferes with the formation of cementite, allowing martensite to form with slower quench rates, resulting in high speed steel. On the other hand, sulphur, nitrogen, and phosphorus make steel more brittle, so these commonly found elements must be removed from the ore during processing. Iron has found its usage from a very early part of human civilization, second only to copper, bronze. Steel was known in antiquity, and may have been produced by managing bloomeries, iron-smelting facilities, where the bloom contained carbon. Evidence of the earliest production of high carbon steel in the Indian Subcontinent was found in Samanalawewa area in Sri Lanka Wootz steel was produced in India by about 300 BC. Along with their original methods of forging steel, the Chinese had also adopted the production methods of creating Wootz steel, an idea imported into China from India by the 5th century AD. During the early part of the civilization, India was an important trade centre of iron smelting which dates back to about 3000 years. Documentary evidences suggests making of various surgical instruments using iron as one of the constituent in 3rd/4th century BC. Since the 17th century the first