Laboratory Report Experiment for Jigging

Laboratory Report Experiment for Jigging1) INTRODUCTIONJiging is integrity of the peculiar(prenominal) gravity separation methods.The method sepa regularize minerals of different circumstantial gravity by their relative movement in response to gravity. pinpoint sizing is also important in danceging.If the rust is closely sized,it is smooth to get good separation with narrow specific gravity range.Jigging is able for the sizes between 25 mm and 75 microns for minerals and satisfactory for 20 cm and 0.5 cm for coal.2) THEORYJig is an open tank filled with piddle that has blind at the top and spigot or hutch compartment at the bottom.Jig neck may have laborious coarse material(ragging material) .Jigs have screen, concussion duration hutch compartment under the screen and ragging,a layer of heavy material.There ar two actions at work.First one is most important one that is the arrange of hindered settling.When the slurry is subjected to several pulses before it exists the tailings weir of the jig,better separation will get.After repeated pulses,particles proceed graded.Heavy materials be settle at the bottom and light particles settle at the top.The early(a) action is the effect of the wet.Upward flow of water separates particles by their specific gravity.Some conditions present in jigging action are1) Therminal Velocity ab initio particles have an acceleration and increasing speed.When equilibrium is achieved,particles reach their terminal velocity and they settle down at constant rate.2) Free Settling The drop of particles in fluid.3) Hindered Settling The hindered settling conditions prevail when the proportion of solids in the flesh increases.The effect of particle crowding becomes more apparent and falling rate of particles begins to decrease.The governing body begins to behave as a heavy liquid whose constriction is that of the pulp rather than that of the carrier liquid.Mechanisms1) Differential Initial Acceleration The initial accel eration is dep shoemakers lastent only on the densities of the solid and the fluid.It is necessaryu that short jigging make pass to separate small heavy particles to light particles.2) Consolidation Trickling In integrating stage,where the thumping particles in the bed come close to each other leaving relatively large interstices filled with draining water racecourse down as a result of the suction part of the strike.breakup may be achieved over the screen or trough the screen in jigging.The operation parameters of jigs are1) Dilution It is the amount of water.High dilution is necessary to remove large quantity of materials.2) Screen Aperture It must be as large as possible,consistent with break size to minimize resistance to flow.3) dig and Frequency Stroke is moving distance of the piston and it depends on particle size.Frequency is the number of stroke per time.4) Feed Rate and Particle Size Range Jigs have soaring unit capacity and can achieve good recovery in particle si ze under 150 pm.3) OBJECTIVES-To wield the social stratification care for-As a function of the value of concentration criteria,observing the rate of stratification-To observe the effect of the ragging material-To observe the effects of the operating variables4) MATERIALS AND EQUIPMENT-multi compartment piston casing laboratory jig steel balls as ragging material-crushed heavy mineral with the size of -3mm +0,5mm-crushed light material wit the size of -3mm +0,5mm-chromite5) PROCEDURE-prepare a mixture of heavy and light minerals-fill the jig wit hutch water-add the feed-add steel balls as ragging material-start the jig and observe the stratification-empty the stratified material-collect the light product6) DISCUSSIONa) Jigs The methods operate by differences in specific gravity. Jigs rely on stratification in a bed of coal when the carrying water is pulsed. The shale tends to sin, and the cleaner coal rises. The basic jig, Baum Jig, is suitable for larger feed sizes. Although the Baum Jig can clean a gigantic range of coal sizes, it is most effective at 10-35 mm. A allowance of the Baum Jig is the Batac Jig which is used for cleaning fine coals. The coal is stratified by bubbling form directly through the coal-water-refuse mixture in this cleaning unit.For intermediate sizes the same principles are applied, although the pulsing may be from the side or from under the bed. In addition, a bed or hard dense mineral is used to enhance the stratification and stay fresh remixing. The mineral is usually feldspar, consisting of lumps of silicates of about 60 mm size.Jigs offer constitute effective technology with a clean coal yield of 75-85% at about 34% ash content. The jigs are used more much than dense-medium vessels because of their larger capacities and cheaper costs.b) Baum jigs and Batac jigsi) Baum jigs A baum jig with a screen deck comprising, in combination, a number of water cisterns each having a feed end and a discharge end and arranged in a serie s-paralleled musical arrangement withsymmetrical short letter house opened at the bottom and located infra the screen deck transversely to the axis of the jig, state symmetrical stress chambers comprising plates as sections of a cylindrical surface, the symmetry axes of said tune chambers beingdeflected from the perpendicular by an angle of 5 to 15 toward said feed end, said chambers having asymmetric guide vanes displaceable in a horizontal direction.ii) Batac jigs There is one decisive difference between an BATAC jig and a Baum jig The water current is not generated in an air chambers are intermittently supplied with compressed air by an electronically controlled valve or flap organisation (pulse generator) . That air is intermittently discharged from the system (at atmospheric pressure) after completion of the upward stroke. Motion is imparted to the water privileged the jig as a function of the pressure generated inside the air chambers. Moreover make-up water is added a t the lowest location of either jigging chamber to intensify the upward current and to dampen the downward current. The feed is stratified according to its density by the pulsating motion of the water when preparing coal, e.g., in refuse, middlings and clean coal.The heavy fraction of the stratified raw material is perceive by floats in accordance with the product qualities required. The system provides for controlled withdrawal of the heavy fraction over a discharge device. Jigging of great comprehensiveness are equipped with independently operating discharge devices fitted with separate sensor and hydraulic units. This configuration ensures optimal product qualities over the entire jig width even in case of non-uniform material distribution.The parts of the batac jig inspirationrefuse outletrefuse ingathering hoppermiddlings outletmiddlings collecting hopperdischarge devicesclean coal overflowair chambersmake-up waterair-distributing tabesair-distributing tankwaste-air collect ing tankwaste-air tubes with silencersvalve control system operate parameters of jigs The observe and control of jig separators is effected by monitoring the time variation within a jig cycle of at least one operating parameter of the jig, and manipulating the operating parameter(s) to produce the desire after form of the time variation within the jig cycle. Operating parameters include bed voidage, water level, particle velocity in the bed and water or air pressure.c) An example of flow sheetIn the flow sheet below, you can see the details of this jigging process as it exists on a Superior mill floor. Copper rock from the mold enters the classifier and is directed to one of four jig sieves. These jigs work in tandem and both pig and tailings are removed during the process (the T and C in the diagram) . The middlings are then sent on to a distributer box, which sends the tailings off to one of four series of refining jigs. More copper and tailings are removed as the middlings are sent on to the wash out floor.7) RESULTSIn this experiment, we have learned the working principle of the jig, the effect of the ragging layer, the stratification process, the effect of operating parameters of jigs. Jig separate the minerals by the effect of specific gravity, and some other forces such as hindered settlings of minerals etc. and the minerals has a layer (stratification) by means of an upward water and the help of the ragging layer. In addition, there are some parameters which effect the separation. They are design parameters such as stroke and frequency and operating parameters such as feed rate and particle size range. Furthermore, if we supply a narrow size range of the minerals to be separated, we can increase the effect of specific gravity and have a good separation.