1. Australian Coal Preparation Society DENSE MEDIUM CYCLONE WORKSHOP Presented By: J.A. Engelbrecht JUNE 2011

2. Contents  DMC Process  Dense Medium Cyclones  Cyclone Design  Performance Constraints  DMC Factors  Operational Parameters  Washability  Flow Sheets  Fine DMC Separation  Conclusions

3. DMC Process Typical DMC Process Flow Sheet

4. Typical Dense Medium Process Flow Sheets Coal Process DMC Flow Sheets

5. Typical Dense Medium Process Flow Sheets DMC Flow Sheets

6.  Efficiency Test - Measure System Efficiency - Sampling Standards on Large Capacity Screens? - Sampling Error Bars? Inside a Dense Medium Process DMC Flow Sheets

7. Dense Medium Cyclones

8. Cyclone Design Cyclone Dimensions: DSM vs. Multotec Effect on Efficiency Effect of Cyclone Configuration

9.  DSM Formula for Cyclone of Standard Configuration Inlet = 0.2 x D Vortex Finder = 0.43 x D Spigot = 0.7 x V.F (0.3 x D) Cone Angle = 20 Deg. No Barrel Section Formula gives the total Volumetric Capacity of the cyclone as a function of the Feed Head Cyclone Dimensions: DSM vs. Multotec Cyclone Design

10. Cyclone Dimensions: DSM vs. Multotec Cyclone Design Tangential Involute Scrolled Evolute

11. Cyclone typeDSMMultotec DiameterDD Inlet0.2xD – Tangential0.2xD,0.25xD,0.3xD – Scrolled Evolute Cone Angle20 Degrees Vortex finder0.43xD0.43xD,0.5xD Spigot0.7xVF0.7xVF, 0.8xVF BarrelNoYes Cyclone Dimensions: DSM vs. Multotec Cyclone Design

12.  Scrolled Evolute Entry - Increases capacity by 20 %  B, AB and A Inlets  A and XA Vortex Finders  Barrel Section - Increase Capacity by 5 -10% Cyclone Dimensions: DSM vs. Multotec Cyclone Design Cyclone Design influences the capacity and therefore explains the deviation from the DSM standard

13. Multotec Standard Capacity CyclonesMultotec High Capacity Cyclones Cyclone Diameter (mm) Max Particle Size (mm) Coal Feed (t/h) Cyclone Diameter (mm) Max Particle Size (mm) Coal Feed (t/h) 51034545105199 610418161061145 660449766066175 7104711471071207 8005314980080270 9006019690094355 1000672491000100454 1150773511150115638 1300874681300130854 14509760814501451108 Cyclone Dimensions: DSM vs. Multotec Cyclone Design

14. Effect of Cyclone Configuration Cyclone Design  Inlet Head - Particle Size - Cyclone Capacity  Vortex Finder - Spigot : VF < 0.8 : 1  Spigot - Based on minimum M:O ratio of 1.5:1  Barrel - Cyclone Capacity - Cyclone Efficiency  Pressure - Cyclone Capacity

15. Performance Constraints Cyclone Constraints Factors Influencing Performance

16.  A DMS Cyclone is sized with reference to three Criteria The size of cyclone selected will be the largest needed to satisfy all three of the following: 1.Volumetric Capacity 2.Top Size 3.Spigot Capacity Cyclone Constraints Performance Constraints

17. STREAM M:O RATIO FEED≥ 3 OVERFLOW≥ 2.5 UNDERFLOW≥ 1.5 Cyclone Constraints Performance Constraints

18. Cyclone Constraints Performance Constraints US Bureau of Mines

19. Cyclone Constraints Performance Constraints A Swanson

20. Cyclone Constraints Performance Constraints US Bureau of Mines

21. DESCRIPTIONSIZE FEED0.33 x D Inlet = D Max HANGUP SIZE0.7x D Max BREAKAWAY SIZESee Graph Factors Influencing Performance Performance Constraints

22. Factors Influencing Performance Performance Constraints

23. Factors Influencing Performance Performance Constraints

24. Factors Influencing Performance Performance Constraints A Swanson

25. Factors Influencing Performance Performance Constraints

26. Recommended Size Distribution Limits Factors Influencing Performance Performance Constraints

27. Large Particles require large diameter cyclones which requires large volumes If solids feed rate is low then alternative equipment must be considered Factors Influencing Performance Performance Constraints

28. High solids feed rate require large cyclone diameters If feed grading is very fine, multiple smaller diameter cyclones must be considered Factors Influencing Performance Performance Constraints

29. Factors Influencing Performance Performance Constraints  Underflow Capacity - M:O Ratio ≥ 1.5 - Volumetric Split = F(D u /D vf ) - Maximum D u /D vf = 0.8 JKMRC

30. Spigot size determined by mass recovery to underflow Once selected, Spigot:Vortex finder ratio needs to be checked Spigot diameter also affects differentials - Normal Spigot = 0.7 x VF - High Capacity Spigot = 0.8 x VF Factors Influencing Performance Performance Constraints

31. DMC Factors Normalised Epm Relative Cut Density

32. DMC Factors Normalised Epm

33. DMC Factors Normalised Epm

34. DMC Factors Normalised Epm

35. DMC Factors Normalised Epm

36. DMC Factors Relative Cut Density

37. DMC Factors Relative Cut Density

38. DMC Factors Relative Cut Density

39. Normalised Epm and Relative Cut Density - Jigs DMC Factors Relative Cut Density

40. Operational Parameters Pressure Medium Density Control Cut Density Distributors

41. Operational Parameters Pressure J Steyn

42. Operational Parameters Pressure J Steyn

43. Operational Parameters Medium G J de Korte

44. Operational Parameters Medium

45. Operational Parameters Medium If differentials are too big, hang-up of particles can occur

46.  Two Types of Hang-Up can Occur  Hang – Up of Coarse Sinks Particles Diamond Industry – Concern Other Applications – Accelerated Wear Thought to be caused by Medium Instability Can be overcome by increasing the spigot size  Hang – Up of Tramp Metal Caused by irregular shape and size Can be overcome by increasing the spigot size Use Cast Iron Cones Operational Parameters Medium

47. Poor Control Operational Parameters Density Control

48. Operational Parameters Density Control F Breedt

49.  Factors Affecting Cut Density –Medium stability –Operating pressure –Cyclone size –Spigot size  In order for parallel cyclones or modules to have the same cut densities the following is required: –Cyclone dimensions must be equal –Medium properties must be the same –Pressure must be equal –Feed rate must be equal –Surface moisture must be equal –Distribution must be equal Operational Parameters Cut Density

50. Operational Parameters Distributors

51. Washability Near Density Organic Efficiency Cyclone Results

52. Organic Efficiency = Actual Yield Theoretical Yield Washability Organic Efficiency

53. Washability Near Density

54.  Defined as - The % (D x ) of NEAR DENSITY material which lies within ± 0.1 RD intervals on either side of the Separation Density. (New standard +/- 0.05) D x, %Degree of Difficulty 0 – 7Simple 7 – 10Moderate Difficult 10 – 15Difficult 15 – 20Very Difficult 20 – 25Exceedingly Difficult > 25Formidable Washability Near Density

55. Increase in Cut density = Increase in EP value Washability Near Density

56. Effect of Poor Efficiency Washability Near Density

57. Different Coal Sources = Different Approaches / Recommendations Washability Near Density

58. Washability Near Density D W Horsfall

59. 800mm Cyclone 4 Seam 800mm Cyclone 2 Seam Separation Density 1.481.60 Circ Medium RD 1.421.52 Ecart Probability 0.020.03 Ave Particle Size 7.00 Near Density Material 25.308.40 Theoretical Yield 38.8079.82 Organic Efficiency 89.5599.10 Sink in Float 4.871.31 Float in Sink 4.911.68 Total Misplaced 9.772.99 Actual Yield 34.7479.11 Quality 28.00 Washability Cyclone Results – Various Seams

60. Washability Cyclone Results - MAX1450

61. Flow Sheets Basic Flow Sheet Design Parameters / Inputs Split DMC Flow Sheet Idealised Flow Sheet

62. Australia Southern Africa Flow Sheets Design Parameters / Inputs

63. Medium Density Screen 1 Aperture Hydro Cyclone D50Feed PSD Cyclone Diameter 1.350.7 mm0.07 mmFine420 mm 1.4251.5 mm0.1 mmMedium900 mm 1.53 mm0.13 mmCoarse 1450 mm HydrocycloneScreen 1 Rf0.05 alpha1.76 SizeEpCut Density 1.180.101.68 0.710.101.68 0.220.141.88 0.071.022.14 In all cases the plant was fed 1000 tph Flow Sheets Design Parameters / Inputs Sizing Spirals

64. Flow Sheets Basic Flow Sheet

65. Flow Sheets Basic Flow Sheet

66. Flow Sheets Split DMC Flow Sheet

67. Flow Sheets Split DMC Flow Sheet

68. Flow Sheets With Flotation Without Flotation

69. X ≈ 5mm Z = 0.1 to 0.3mm y=?mm Maybe even consider desliming before flotation. The issue of moisture content to be balanced against energy recovery Optimise the Feed PSD Flow Sheets Idealised Flow Sheet

70. Flow Sheets Conclusions  SA ore more variable than Australian ore in terms of process parameters  Increased liberation improved the overall yield and quality –This is valid for both Australian and Southern African Coal –However if there is no flotation, finer crushing has an adverse effect on the yield of an Australian coal, due to loss of fine coal –The quality does improve for finer crushing  Sending a larger size range to the fine cyclones has a beneficial impact in terms of coal quality and quantity (There is also the benefit of additional control) –This is less pronounced on Australian coal, when there is no flotation

71. Flow Sheets Conclusions  Controlling Medium density has an inter-play between coal quality and yield  Splitting the circuit into a fines DMS and a coarse DMS has the benefit of independently controlling the cut density and medium to ore ratios of the two circuits –This is of considerable benefit when there is a variable ore body  Using smaller cyclones has a beneficial impact in the fines circuit –The effect of the cyclone size for the large fraction in the split circuit was insignificantly small

72. Fine DMC Separation Conclusions Summary

73. Fine DMC Separation Summary

74. Fine DMC Separation Summary

75. Fine DMC Separation Summary

76. Test Plant at South Witbank Colliery Flow Sheets Idealised Flow Sheet G J de Korte

77.  The fine circuit enables dense medium separation to be extended to particles as small as 0.2mm.  Dense medium separation is more efficient and flexible than water based equipment like Spirals, TBS or WOC.  It also highlights that a combination of water only processes can provide better overall results. Fine DMC Separation Conclusions

79.  DMC separation is very efficient even for large diameter cyclones  It is doubtful whether the current operating standards can fully utilize the potential efficiency of DMC on a continuous basis  There is merit to consider a split DMS circuit i.e. coarse and fine  Finer crushing may give better overall results  DMS is the most efficient and flexible process down to 0.5mm or even 0.2mm  Efficiency tests measures the total system and depends on a number of parameters Fine DMC Separation Conclusions

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