Beneficiation of Iron Ores

These ores ca n be directly utilise in the output signal of campaign and steel. All other ores charter benefaction and certain fulfill in the first place they argon utilise in t he harvest-festivalion of straighten out and steel. pitiful grade compress ores squeeze outnot be use as such for the production of atomic derive 26 and SST eel and need to be upgraded to repress its gangue mental object and increase its Fee capability. The dish up pick out to upgrade the Fee content of variant n ore is known as bid ore benefaction (108). However, Iron ores from different sources pay their own peculiar mineralogy cal characteristics and require the circumstantial benefaction and teleological treatment to lounge about the best product out of it.Also for telling Ben affectation treatment, legal oppress, contrition, and masking of the ore is demand for which suitable crush, contriteness, and SC reining technologies ar to be employed. The choice of the benefacti on treatment depends on the nature of the gangue present and its association with the ore structure. some(prenominal) methods/proficiencys such as washing, jigging, magnetised interval, graveness judgment of conviction interval, and flotation n etc. be use to enhance the Fee content of the Iron ore and to reduce its gangue content.These techniques argon used in various combination s for the benefaction of compress ores. For benefaction of a particular compact ore the emphasis is commonly to develop a live effective f moo she et incorporating necessary crushing, corrasion, screening and benefiting techniques which atomic number 18 necessary for the upgrading of the iron or e. A typical flow shred for iron ore benefaction plant is shown in frame 1. 3/13 Fig 1 A typical flow sheet of iron ore benefaction plant roughly of the common methods/ techniques applicable for iron ore influenceing ar described below.Crushing, cranch and screening technique The purpose of exc oriation and re excoriation is to reduce the ore to a coat small en ugh to liberate and recover the valuable minerals. The crushing, grinding and screening systems of an BIB plant atomic number 18 to be designed t ripening into ac front the requirements of the vote outstream benefaction deales. The crushing units may overwhelm chief(a), secondary, t artery and quaternary crushing systems. Jaw, gyrator, cone, and roll crushers be used for ore crushing. Semi toughens grinding and AU toughens grinding circuits are used for grinding the ore.Both rod move and ball mills are used for this purpose. Capital coronation and decorous action costs of grinding equipment are high. Hence economics execute a large part in planning for the degree of crushing and grinding perform d to prepare ore for benefaction. new(prenominal) factors considered in de lineining the degree of crushing and grinding embarrasss the value concentrate Zion of the ore, its mineralogy, scratchiness and m oisture content. Closed circuit grinding minimizes over grinding of very breakable ore normally of undo in the ore bodies of our region.The much the recirculation load the less is the over grinding of particles. Washing and skew-whiff scrubbing This process is primitive and widely used in lumpy iron ore impact to discotheque edge and remove friable and sonant laterality materials, fine materials and limitation remains particles adhering to the ore. askew scrubbing is alls o profitable in hard and porous ores, which ever take in cavity/ pores filled with sonorous material that need substantial removal. gloominess breakup This technique is used where iron bearing minerals are free from associated g angle materials.The unique(predicate) gravity of iron bearing minerals is usually higher(prenominal) than the specific gravity of gangue materials. Effectiveness e faculty of the gravity disengagement depends largely on to proper crushing and sizing of the ore so as to ensur e a proper size flow to the gravity time interval equipment and alike removal of slime from the equipment. A large numbers of equipment/ processes functioning on gravity separation principle are available. Some of t hem are described below. Dense media separation -? The process is also known as overburdened media separate on. The process is used for mutual ores (size float mm to 50 mm.Ground convey silicon of 300 net income size is used as suspension to unction et a parting immersion of 33. 2 which is sufficient for angle materials to float and fall separated. The suspension material is recover vibrating reed by using low fanaticism magnetized separators (LIME). Feed for the dense media separation must be hard and exhort 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 bosoms to collapse separation betwixt ore an d gangue material.Ground Frederickson of 325 mesh size is used as a media in cyclone. Jigging Jigging is a gravity engrossment technique where the iron ore is seep rated into slatternly absorption segment, medium density divide 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 catamenia film separation devices. General pop ration is a continuous gravitational laminar flow down(p) on an inclined surface. The mechanism of separation involves primary coil and SE secondary flow patterns.The primary flow is essentially the slurry stream down the turn trough under the force of gravity. The sec Andrea flow pattern is stellate across the trough. Here the uppermost placid layers comprising higher density particles move out-of-door from t he centre period the lowermost concentrate layers of higher density particles move towards the centre. Spirals require ad dition of water at various orders down the whorled to assist washing of the iron ore, I. E. Transporting outdoor(a) the light gangue from the dense ore. The e add up of wash water and its distribution down the spiral trough can be adjusted to meet the operating requirements.Point count roll minimizes the total water requirements by efficiently directing water into the flowing pulp 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 pertinence 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 va luables from slimes and tails. Cyclones Cyclones used for concentration of iron ores are of several types. T hose include hydrochloric, stub cyclone and heavy media cyclone. Cyclones are cost effective and simple in their construction. The e main parts of a cyclone dwell of cyclone diameter, the inlet nozzle at the point of entry into the cater chamber, vortex finder, cyclical medical section and cone section.They have proper geometrical relationship between the cyclone diameter, inlet area, vortex find ere, summit orifice, and sufficient length providing retention time to properly classify particles. As the feed enters the chamber, a rotation Of the slurry inside of the cyclone begins, do centrifugal forces to accelerate the movement of the particles towards the oh term wall. The particles migrate downward in a spiral pattern through the cylindric section and into the conical section. At this poi NT the smaller mass particles migrate toward the center and spiral upward and out through the vortex finder, discharging through the overflow pipe.This product, which contains the finer particles and the volume of the water, is termed the overflow and should be discharged at or near atmospherical pressure. The higher ass particles remain in a downward spiral path on the walls of the conical I section and in stages exit through the apex orifice. This product is termed the underflow and also should be discharged at or nee r atmospheric pressure. magnetic separation Magnetic separation technologies are used to take the profit 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 both 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. showtime forcefulness separators use magnetic fields between 1000 to 3000 gauss. Low intensity techniques are norma lly used on magnetite ore as an tawdry and effective separation method. graduate(prenominal) intensity separators employ fields as toilsome as 20,000 gauss. This method is u sow to separate vaguely magnetic iron ores such as hematite, from nonmagnetic or less magnetic gangue materials.Other factors most-valuable 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 namely (I) c bobbling, (ii) cleaning/roughing and (iii) finishing. each stage may employ several drums in a series to improve separation efficiency. Each s successive stage whole kit and boodle on finer particles as a result of the removal of oversized particles in earlier separations. Cobblers work on big 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 magnetic ores Induction roll magnetic separation (RIMS) for concentrating dry ores Flotation process Flotation process uses a technique where particles of one mineral or base of minerals are made to adhere preferentially to air bubbles in the presence of a chemical substance reagent.This is achieved by using chemical reagents t hat that preferentially play off with the desired mineral. Several factors are important to the success of flotation activities. These include link up remit of particle size, use of reagent congruous with the mineral, and water conditions that will not intervene with the attachment of the e reagents to the mineral or the air bubble. Today flotation is in the main used to upgrade concentrates resulting from mage entice separation.Flotatio n to be used all alone as a benefaction method is used rarely. Chemical reagents used are in the first place of three main groups namely (I) collectors/ amines, (ii) brothers, and (iii) antifoam. Reagents may be added in a number of forms which include solid, immiscible liquid emulsion a ND solution in water. The concentration of reagents need to be generally controlled during conditioning since adding more reagent than needed d retards the reaction and reduce efficiency.