Beneficiation of Iron Ores

These ores ca n be directly use in the production of crusade and steel. All other ores need benef proceeding and certain actioning originally they atomic number 18 occupy in t he production of straighten out and steel. Low grade iron ores assholenot be utilise as such for the production of iron and SST eel and need to be upgraded to reduce its gangue means and join on its Fee content. The solve adopted to upgrade the Fee content of publicise n ore is known as iron ore benefaction (108). However, cast-iron ores from antithetic sources have their own peculiar mineralogy cal characteristics and aim the specific benefaction and teleological treatment to get the best product out of it.Also for effective Ben cant treatment, effective crushing, craunch, and screening of the ore is required for which suitable crushing, rubbing, and SC reining technologies be to be employed. The choice of the benefaction treatment depends on the nature of the gangue present and its stan d with the ore structure. Several methods/ techniques such as washing, jigging, magnetised insulation, gravity time interval, and flotation n etc. Are employ to enhance the Fee content of the Iron ore and to reduce its gangue content.These techniques be used in various combination s for the benefaction of iron ores. For benefaction of a particular iron ore the stress is usually to develop a cost effective point she et incorporating necessary crushing, grinding, screening and benefiting techniques which are necessary for the upgrading of the iron or e. A typical f scurvy sheet for iron ore benefaction jell is shown in physique 1. 3/13 Fig 1 A typical flow sheet of iron ore benefaction plant Some of the common methods/ techniques relevant for iron ore bear on are described below.Crushing, grinding and screening technique The purpose of grinding and regrinding is to reduce the ore to a surface small en ugh to liberate and recover the valuable minerals. The crushing, grind ing and screening systems of an BIB plant are to be excogitationed t aging into account the requirements of the downstream benefaction processes. The crushing units may include primary, second gearondary, t artery and intravenous depleteing crushing systems. Jaw, gyrator, cone, and roll crushers are used for ore crushing. Semi toughens grinding and AU toughens grinding circuits are used for grinding the ore.Both rod mills and nut case mills are used for this purpose. Capital investment and proper action costs of grinding equipment are high. Hence economics play a bounteous part in planning for the grade of crushing and grinding perform d to prepare ore for benefaction. Other factors considered in de preconditionining the degree of crushing and grinding includes the value concentrate Zion of the ore, its mineralogy, hardness and moisture content. unsympathetic circuit grinding minimizes over grinding of very friable ore unremarkably of undo in the ore bodies of our region.Th e more the recirculation load the little is the over grinding of particles. Washing and wet scrubbing This process is primitive and childlikely used in lumpy iron ore processing to disco edge and adjourn friable and soft laterality materials, fine materials and limitation clay particles adhering to the ore. smashed scrubbing is alls o useful in hard and porous ores, which perpetually have cavity/ pores filled with clayey material that need square(a) removal. Gravity time interval This technique is used where iron object minerals are free from associated g angle materials.The specific gravity of iron bearing minerals is usually higher than the specific gravity of gangue materials. Effectiveness e force of the gravity withdrawal depends largely on to proper crushing and coat of the ore so as to ensure a proper size feed to the gravity separation equipment and besides removal of slime from the equipment. A large numbers of equipment/ processes functioning on gravity separa tion principle are available. Some of t hem are described below. Dense media separation -? The process is also known as heavy media separate on. The process is used for coarse ores (size range mm to 50 mm.Ground ferry te of 300 mesh size is used as suspension to lick et a parting slow-wittedness of 33. 2 which is sufficient for angle materials to vaunt and get separated. The suspension material is recover reed by victimisation low speciality magnetized separators (LIME). Feed for the dense media separation moldiness be hard and compact with non poor us gangue material. Heavy media cyclone The process is used for iron ore fines with size range o f 0. Mm to 6 mm. The cyclone type separator utilizes centrifugal as well as gravitative forces to make separation between ore an d gangue material.Ground Frederickson of 325 mesh size is used as a media in cyclone. Jigging Jigging is a gravity ingress technique where the iron ore is seep rated into light density fraction, medium de nsity fraction and heavy density fraction. Size fraction of the iron ore used for gig Eng is 0. 5 mm to mm. Http//asparagus. Com/beneficiationofironores/ Spirals Spiral concentrators are flowing hire separation devices. General pop ration is a continuous gravitational laminar flow down on an inclined surface. The mechanism of separation involves primary and SE secondary flow patterns.The primary flow is fundamentally the slurry flowing down the spiral trough under the force of gravity. The sec Andrea flow pattern is radial across the trough. Here the uppermost silver-tongued layers comprising higher density particles move away from t he essence while the lowermost concentrate layers of higher density particles move towards the centre. Spirals require addition of water at various points down the spiral to pay heed washing of the iron ore, I. E. Transporting away the light gangue from the dense ore. The e get alongity of wash water and its distribution down the spiral trough ca n be adjusted to meet the operating requirements.Point count roll minimizes the total water requirements by efficiently directing water into the flowing frame at the most effective angle. Feed size app logicality is in the range of 0. 3 mm to 1 mm. Spirals are normally operated at a pulp density of 25 % to 30 % solids. Tables -? Tables have wide range of application in gravity treatment of iron ore s. Tables are normally used in cleaning and scavenging circuits. Feed size pertinency is in the range of 0. 3 mm to 1 mm. Spirals are n armorial operated at a pulp density of 25 % to 30 % solids.Multi gravity concentrator They are under development stage and are design Ned to treat fines and ultramarine particles Of iron ore. They are useful in processing of valuables from slimes and tails. Cyclones Cyclones used for assimilation of iron ores are of several types. T irrigate include hydrochloric, stub cyclone and heavy media cyclone. Cyclones are cost effective and undecomposable i n their construction. The e main parts of a cyclone consist of cyclone diameter, the entry nozzle at the point of entry into the feed chamber, vortex finder, cyclical medical section and cone section.They have proper geometrical kin between the cyclone diameter, inlet area, vortex find ere, apex orifice, and sufficient distance providing retention time to properly classify particles. As the feed enters the chamber, a rotation Of the slurry inside of the cyclone begins, causing centrifugal forces to accelerate the movement of the particles towards the oh term wall. The particles transmigrate downward in a spiral pattern by dint of the cylindrical section and into the conical section. At this poi NT the smaller mass particles migrate toward the center and spiral upward and out finished the vortex finder, discharging through the overflow pipe.This product, which contains the finer particles and the majority of the water, is termed the overflow and should be discharged at or near atmospheric pressure. The higher ass particles remain in a downward spiral path along the walls of the conical I section and gradually exit through the apex orifice. This product is termed the underflow and also should be discharged at or nee r atmospheric pressure. charismatic separation Magnetic separation technologies are used to record the advantage Of the differ once in the magnetic properties for separating iron ore from the non magnetic associated gangue materials.Magnetic separation can be condo acted in either a dry or wet environment, although wet systems are more common. Magnetic separation operations can also be categorized as either low or high I density. Low flashiness separators use magnetic fields between 1000 to 3000 gauss. Low intensity techniques are normally used on magnetite ore as an inexpensive and effective separation method. High intensity separators employ fields as strong as 20,000 gauss. This method is u seed to separate frail magnetic iron ores suc h as hematite, from nonmagnetic or less magnetic gangue materials.Other factors important t in determining which type of magnetic separator system is used include particle size and the solids content of the ore slurry feed. Http// asparagus. Com/beneficiationofironores/ 5/13 Typically magnetic separation involves three stages of separation videlicet (I) c bobbling, (ii) cleaning/roughing and (iii) finishing. individually stage may employ several drums in a series to improve separation efficiency. Each s successive stage melt downs on finer particles as a result of the removal of oversized particles in earlier separations. Cobblers work on larger particles and reject substantial percent of feed as tails.Several types of magnetic separation technologies are used. These are descried bed below. Wet and dry, low intensity magnetic separation (LIME) High gradient magnetic separation (HIGHS) Wet high intensity magnetic separation (WHIMS) Roll magnetic separators for processing weak magn etic ores Induction roll magnetic separation (RIMS) for concentrating dry ores Flotation process Flotation process uses a technique where particles of one mineral or group of minerals are made to bind preferentially to air bubbles in the presence of a chemical reagent.This is achieved by using chemical reagents t hat that preferentially react with the sought after mineral. Several factors are important to the success of flotation activities. These include merge remit of particle size, use of reagent compatible with the mineral, and water conditions that will not interfere with the attachment of the e reagents to the mineral or the air bubble. forthwith flotation is primarily used to upgrade concentrates resulting from mage entice separation.Flotation to be used all alone as a benefaction method is used rarely. Chemical reagents used are mainly of three main groups namely (I) collectors/ amines, (ii) brothers, and (iii) antifoam. Reagents may be added in a number of forms which i nclude solid, incompatible liquid emulsion a ND solution in water. The concentration of reagents need to be loosely controlled during conditioning since adding more reagent than needed d retards the reaction and reduce efficiency.