Magnetic Separation and Iron Ore Beneficiation Oct04

Magnetic Separation and Iron Ore Beneficiation...

Magnetic Separation and Iron Ore Beneficiation Magnetic separation is an old technique for the concentration of iron ores and for the removal of tramp iron. Since 1849, a number of patents on magnetic separation have been issued in USA, and texts of some of the patents before 1910 describe a variety of magnetic separators for mineral processing. Magnetic separation methods are used to take the advantage of the difference in the magnetic properties for separating iron ore from the non-magnetic associated gangue materials. Magnetic separation can be conducted either in a dry or in a wet environment, although wet systems are more in use. Magnetic separation is a physical separation of discrete particles based on the three way competition between tractive (i) magnetic forces, (ii) gravitational, hydro-dynamic drag, frictional, or inertial forces, and (iii) attractive or repulsive inter-particle forces. These forces combine to act differentially on particles of differing magnetic properties in the feed material. Fig 1 shows the principle of the magnetic separation. Fig 1 Principle of magnetic separation The forces in the magnetic separators which compete with the magnetic forces and act on all of the particles which travel through the separator are those of gravity, hydrodynamic drag, friction, and inertia. Depending on the type of magnetic separator, certain of these forces can have higher or lesser importance. The gravitational force is significant for large particles while the hydrodynamic drag force is significant for the small particles. Thus in the magnetic separator which treats large particles in dry form, the feed material passes through the force of gravity. The magnetic forces need to be sufficient to hold the magnetic particle against the competing force of gravity. In a wet separator for small particles, the magnetic force need to be larger than the...

Low grade Iron Ore Beneficiation and the Process of Jigging Sep25

Low grade Iron Ore Beneficiation and the Process of Jigging...

Low grade Iron Ore Beneficiation and the Process of Jigging Iron ore resources are getting consumed at an accelerated rate because of the growth in the production of iron and steel. Due to this reason the availability of high grade iron ore is reducing and the supply of high grade iron ore to iron and steel plants is declining sharply. Hence, the scenario is steadily shifting towards the use of low grade iron ores and slimes which are stock piled in the mine’s sites for years. These dumped slimes also, in fact, falls in the category of low grade iron ore.  Also, some of the ores of iron have a complex mineralogical composition and do not respond to conventional beneficiation techniques. Modern beneficiation processes allow for effective and low cost upgrading of lump, fines and ultra-fines of such ores. Since the iron ores consist of several compositions, mineralogies, shapes, and sizes, so there is no ‘one size fits all’ approach to the beneficiation of iron ore. Most of the ‘run-of-mine’ (ROM) iron ore contain a large percentage of other materials which need to be removed through the process of beneficiation before the ore attains the specifications needed for its use. The extent of the beneficiation techniques employed depends on the level and nature of diluents and the form of distribution of the gangue and impurities in the ore structure. Liberation of ore is an essential step for making it responsive to the beneficiation techniques. For selection of appropriate techniques, it is necessary to carry out first the mineralogical assessment of the ore so as to get the insight into the ore and to know the gangue association, and grain size etc. There are several issues relating to categorization and beneficiation of low grade iron...

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...