Processes for Beneficiation of Iron Ores Mar28

Processes for Beneficiation of Iron Ores...

Processes for Beneficiation of Iron Ores  Iron is an abundant element in the earth’s crust averaging from 2 % to 3 % in sedimentary rocks to 8.5 % in basalt and gabbro. Because iron is present in many areas, it is of relatively low value and thus a deposit must have a high percentage of metal to be considered ore grade. Typically, a deposit must contain at least 25 % iron to be considered economically recoverable. Over 300 minerals contain iron but five minerals are the primary sources of iron ore. They are (i) magnetite (Fe3O4), (ii) hematite (Fe2O3), (iii) goethite (Fe2O3.H2O),  (iv) siderite (FeCO3), and (v) pyrite (FeS2). Mining of iron ores requires drilling, blasting, crushing, screening, and blending of the ores. Crushing and screening are an integral part of ore producing facilities. Crushing usually involves a primary crusher and secondary crushers operating in closed circuit with vibrating screens. Equipment selection is determined largely by the friability of the ore. Most of the screening operations on high grade ores are dry except when the fines fraction can be effectively upgraded by desliming. Iron ores normally fall within one of the three categories namely (i) direct shipping, or high grade ores, which contain enough iron to be charged to the iron making furnace directly and may only require crushing, screening, and blending, (ii) associated low grade merchant ores which occur around the high grade ores that can be mined concurrently and which require minor upgrading by washing to increase their iron content, (iii) low grade ores that requires extensive crushing, grinding and concentration to produce an acceptable concentrate. The iron ores that fall within these three categories have quite different processing requirements. To obtain a uniform product, ores of different grades, compositions, and sizes...

Beneficiation of Iron Ores Apr03

Beneficiation of Iron Ores...

Beneficiation of Iron Ores Iron ore is a mineral which is used after extraction and processing for the production of iron and steel. The main ores of iron usually contain Fe2O3 (70 % iron, hematite) or Fe3O4 (72 % iron. magnetite). Ores are normally associated with unwanted gangue material. Grade of iron ore is usually determined by the total Fe content in the ore. Run of mines ores after dry or wet sizing, if it contains normally greater than 62 % of Fe, are known as ‘natural ore’ or ‘direct shipping ore’ (DSO). These ores can be directly used in the production of iron and steel.  All other ores need beneficiation and certain processing before they are used in the production of iron and steel. Low grade iron ores cannot be used as such for the production of iron and steel and need to be upgraded to reduce its gangue content and increase its Fe content. The process adopted to upgrade the Fe content of iron ore is known as iron ore beneficiation (IOB). However, Iron ores from different sources have their own peculiar mineralogical characteristics and require the specific beneficiation and metallurgical treatment to get the best product out of it. Also for effective beneficiation treatment, effective crushing, grinding, and screening of the ore is necessary for which suitable crushing, grinding, and screening technologies are to be employed. The choice of the beneficiation treatment depends on the nature of the gangue present and its association with the ore structure. Several methods/techniques such as washing, jigging, magnetic separation, gravity separation, and flotation etc. are used to enhance the Fe content of the Iron ore and to reduce its gangue content. These techniques are used in various combinations for the beneficiation of iron ores. For...