Pilot plant testing for hydrocyclone design


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Pilot plant testing for hydrocyclone design

  2. 2.  Introduction Design variables Hydrocyclone efficiency Hydrocyclone design TestworksCONTENT2
  3. 3.  A hydrocyclone is a size classifier used toprocess slurries. The separation mechanism is based onenhanced gravity and takes advantage ofparticle size and density.[5]INTRODUCTION3 Recovery of water to overflow isgenerally high (around 90%). It followsthat the coarser particles exit throughthe underflow as a dense slurry.[5]
  4. 4. INTRODUCTIONSlurry is injected into thecylindrical zoneCycloning starts to takeplace in the feedchamber.Heavier particles moveto the outer walls bycentrifugal forces andmove toward the apex.Lighter particles stay near thecenter of the cone and are carriedaway by the vortex finder.[1,7]
  5. 5.  Classification does not take-place throughout the whole bodyof the cyclone.5INTRODUCTIONRegion A: unclassified feedRegion B: fully classified coarse materialRegion C : fully classified fine materialRegion D: classification takes place.Across this region, decreasing sizes showmaxima at decreasing radial distancesfrom the axis.[1]
  6. 6.  Hydrocyclone design objectives: Maximum efficiency Maximum capacity Lower operating costs The process design criteria will be based on an interpretationof testwork carried out on the particular ore. As more test work result are available and the orecharacteristics and process become better defined acontinuous updating of the design criteria is under taken. Pilot scale testing is regerded as the most reliable method ofselecting flowsheets and generating design criteria forequipment sizing and selection.[4]6INTRODUCTION
  7. 7. Cyclone geometryArea of the inletnozzleCyclone diameterCylindrical andconical sectionVortex finder andapex orificeFeed featuresSolids concentrationand Size distributionSpecific gravity of solidand liquidSlurry and liquid viscosityInitial pressure of feed7DESIGN VARIABLESCyclone performance0.05 times thecyclone diametersquared−Retention time−Length equal tocyclone diameter−Angle:10°- 20°[1],[2]
  8. 8.  The sharpness of the cut depends on the slope of the centralsection of the partition curve; the closer to vertical is theslope, the higher is the efficiency.[1]8HYDROCYCLONE EFFICIENCY
  9. 9.  Small cyclone diameters give greater efficiency. Efficiency and P increase with height; normally height isbetween 2 and 6 diameters. Smaller cone angle gives better efficiency. Pressure drop is related to efficiency, It increases withefficiency. In practice the efficiency is limited because at highP, velocities become high, and turbulence causes reentrainment and loss of particles. Efficiency increases with mass which increases with particlesize.[1,6]9HYDROCYCLONE EFFICIENCY
  10. 10. EFFICIENCY, FLOWRATE AND P00water Flowrate, Q0ΔP,mofwatercolumnEfficiencyABOptimumOperationEffPTheoryPractice40100[6]
  11. 11.  You should start with calculating cyclone diameter:Step1: Calculate required D50 using mass balance equationsfrom known information.Step2: Calculate D50(base) with multiplying times a series ofcorrection factors designated by C1, C2, and C3:D50C(application) = D50C(base)xC1xC2xC3o C1: influence of the concentration of solids11HYDROCYCLONE DESIGN[2],[3].[4]
  12. 12. Larger amount of finescoarser separationAbsence of finesfiner separation 12HYDROCYCLONE DESIGN this is affected by particlesize and shape and liquidviscosity. higher concentrationresults coarser separation.[2]
  13. 13. o C2: influence of pressure drop• Pressure drop is a measure of the energy being utilized in thecyclone to achieve the separation.• It is recommended that pressure drops, be designed in the 40to 70 kPa range to minimize energy requirements. [2]C2 = 3.27 x ∆P-0.2813HYDROCYCLONE DESIGN
  14. 14. 14HYDROCYCLONE DESIGN Higher pressuredrop finerseparation [2]
  15. 15. o C3: Influence of specific gravity of the solids and liquid GS = Specific gravity of solids GL = Specific gravity of liquid[2]15HYDROCYCLONE DESIGN
  16. 16. D = 0.204 x (D50(base))1.675 [2]16HYDROCYCLONE DESIGND50(base) = D50C(application)/C1xC2xc3
  17. 17.  Then determine cyclone capacity and number ofcyclones: The volume of feed slurry that a given cyclone can handle isproportional to the pressure drop.Number of cyclone= total slurry flow rate /cyclone capacity. Approximately 20% to 25% standby cyclones arerecommended for operational as well as maintenanceflexibility. [2],[3]17HYDROCYCLONE DESIGN
  19. 19.  Determine apex diameter: [2]19HYDROCYCLONE DESIGN
  20. 20.  Vortex finder diameter:where Dv is the vortex diameter and Dc is cyclone diameter Inlet nozzle diameter:[3]20HYDROCYCLONE DESIGNDi = 0.05 × (Dc)2
  21. 21.  Sizing Measurement Tests Sizing analyses provide useful information on the sizedistribution of a sample of ore or other material, using acomprehensive set of screens and all screening done understandard and unvarying conditions to ensure self-consistencyand reproducibility of the results.[8]21TESTWORKS
  22. 22.  X-ray Diffraction (XRD):Qualitative Identification - mineral presentSemi-Quantitative analysis - identification andestimation of major/minor/trace componentsQuantification of mineral species present - Rietveldquantification[8] The solids Specific gravity of the equivalent Mineral is:[9]22TESTWORKS
  23. 23.  Testwork 1: To collect the data on the operationalperformance of hydrocyclone, a series of pilot scale tests wasconducted. These experiments were carried out using feed slurryconsisting of quartz particles with a density of 2650 kg/m3. The feed sizedistribution is shown in Table 1.23TESTWORKS
  24. 24.  The liquid phase was water. A hydrocyclone of 100 mm diameter and 435 mm totallength, at a constant inlet pressure of 10 psi was used. The variable parameters were; the overflow opening diameterin the range of 14–50 mm, the middling flow openingdiameter in the range of 4–12 mm, and the underflowopening diameter in the range of 10–24 mm. The inlet opening diameter was kept constant at 14 mm withall other conditions.[10]24TESTWORKS
  25. 25.  Test rig Fig. 11 shows a schematic diagram of the test rig used in theexperimental work. It comprises a 100 hydrocyclone, a variable speed slurrypump and 80 l baffled sump. The pressure drop across the cyclone was measured with apressure gauge using a diaphragm mounted on the feed inletpipe. Stirring of slurry in the sump was achieved by a mechanicalagitator in conjunction with the turbulence created by thereturning flows and baffles which ensured a completesuspension of solids in the sump.[10]25TESTWORKS
  26. 26. 26TESTWORKSFig. 11. A schematicdiagram of the test rigconstructed at theMineral ProcessingLaboratory, Faculty ofEngineering, AssiutUniversity.[10]
  27. 27.  Test procedure, sampling and data analysis In each test, the appropriate components are selected toobtain the desired hydrocyclone configuration. Feed slurry containing approximately 4.8% solids wasprepared in the sump. After attaining steady statecondition, the overflow, middling flow and underflow streamswere sampled simultaneously for a certain time. This is immediately followed by sampling of the feed stream.The slurry samples are weighed, filtered, dried and reweighedto calculate the flow rates and solids percent in the differentproducts. The obtained results were mass balanced and used forsubsequent calculations and interpretations.[10]27TESTWORKS
  28. 28.  Testwork 2: Particle size distribution of the dispersed phase A proper amount of tracer particles as the dispersion phaseand the continuous phase was mixed in the feed tank andpumped into the pipe line with a centrifugal pump. A return line was set near the inlet of the pump to manipulatethe feed rate and to avoid the strong impact to thehydrocyclone by the inlet flow. The light dispersion was separated and went back to the tankwith the overflow, while the continuous phase went back tothe tank directly with the underflow. The position of the orifices in the hydrocyclone wasdetermined by the research purpose. [11]28TESTWORKS
  29. 29.  For the study of the influence of the vortex finder’s structureparameter on the flow distribution, some representative anduniformly distributed axial cross-section should be chosen toset the orifices. The weighting method was used to test the separationefficiency under the same material system.[11]29TESTWORKS
  30. 30.  The results give a coordinated relationship of vortex finderparameters and performance of hydrocyclones for separatinglight dispersed phase. The size of vortex finder has great influence on thedistribution of the centrifugal separation factor, but thedifferent depth of vortex finder has little influence on thecentrifugal separation factor. With the reduction of the vortex finder diameter, the size ofthe dispersed particles gets smaller and the separation of thehydrocyclone gets better. [11]30TESTWORKS
  31. 31.  Testwork3: Effect of particle size and shape on hydrocycloneclassification The hydrocyclone tests were carried out as follows: 30 L of theslurry, in the slurry tank was circulated by the circulation pumpthrough the circulation line to agitate and disperse the particlesin the slurry. After the slurry flow through the hydrocyclone reached a steady-state, the overflow product (hereafter referred to as OP) from thevortex finder and the underflow product (UP) from the apex of thecyclone were sampled in plastic bottles. the flow rates of the overflow and underflow were measuredusing measuring cylinders and a stopwatch. Both the overflow and underflow products were dried, and thesolids were weighed for calculations of the solid concentrationsof the OP and UP as the solid mass per unit volume of thesamples.[12]31TESTWORKS
  32. 32. 32TESTWORKS
  33. 33.  Size distributions of particles contained in the OP and UPsamples were measured using a laser-diffraction-dispersion-type particle size distribution analyzer, Microtrac MT3300SX(Microtrac Inc.), with the measurement condition:wavelengthof light source, 780 nm;measured range of particlesize, 0.021–1408 μm; measuring time, 30 s; refractiveindex, 1.55 for PTFE, 1.51 for glass flake, 1.33 for water;measure mode, transparent and nonspherical. The results in the table suggest that the settling velocity oflarge particles is smaller than that of small particles whenthe particle Reynolds number is large. In the hydrocyclone tests of PTFE and glass flake, recovery ofcoarser particles as underflow product decreased at high inletvelocities.[12]33TESTWORKS
  34. 34. 34TESTWORKS
  35. 35.  [1] will’s mineral processing technology, eddition7 [2] THE SIZING AND SELECTION OF HYDROCYCLONES, Richard A. Arterburn [3] mineral processing, Dr. Nematollahi [4] mineral processing plant design practice and control,I [5] Fundamental understanding of swirling flow pattern inhydrocyclones, Aurélien Davailles a,b,⇑, Eric Climent a,b, Florent Bourgeoisc [6] apresentation: Powder Technology – Part II, DT275 Masters inPharmaceutical and Chemical Process Technology, Gavin Duffy, School ofElectrical Engineering Systems, DIT [7] a presentation: An Introduction to Basic Hydrocyclone Operation [8] JK hydrocyclone test [9] DESIGNING AND TESTING THE REPRESENTATIVE SAMPLERS FORSAMPLING A MILLING CIRCUIT AT NKANA COPPER/COBALTCONCENTRATORChibwe, P.1, Simukanga, S.1, Witika, L.K.1,Chisanga, P.2and Powell, M. 200535REFERENCES
  36. 36.  [10] Performance of a three-product hydrocyclone Mahmoud M. Ahmeda,, Galal A. Ibrahim a, Mohamed G. Farghaly b, 2008 [11] The coordinated relationship between vortex finder parameters andperformance of hydrocyclones for separating light dispersed phase QiangYang, Hua-lin Wang∗, Jian-gang Wang, Zhi-ming Li, Yi Liu, 2011 [12] Effect of particle shape on hydrocyclone classification KoukiKashiwaya , Takahiko Noumachi 1, Naoki Hiroyoshi, Mayumi Ito, MasamiTsunekawa, 201236REFERENCES