Influence of process on quality

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Influence of process on quality

  1. 1. Influence of process on quality And quality control on process
  2. 2. Why we maintain quality ? It is need of the customer Customer is the king .He sees us in quality price ratio To day mason decides the quality but tomorrow engineer will decide the quality in our country ( house construction , etc) What will happen to us ?
  3. 3. Customer is the king. He is a better business man than you. Tomorrow’s market is competitive with quality/ price ratio. Customer creates the customers. Bon’t brand the quality alone , brand your service too.
  4. 4. Mining crushing preblending Raw meal preparation Raw meal blending Pyro process Clinkercooling Cement grinding Packing & despatch Process steps Concern for Environm ent Q uality control
  5. 5. Process flow diagram and integration of quality Quality control
  6. 6. Variation makes the process and quality to struggle and custome unhappy customer
  7. 7. Mining Well developed mines
  8. 8. Geology and location of boreholes Bore Hole sample
  9. 9. Function of PGNA Analyser Cf 252
  10. 10. Variation is a devil In any process
  11. 11. Lime saturation factor on clinker basis If MgO is below 2 % LSF = 100( CaO – free CaO+0.75 MgO) (2.85 SiO2) + ( 1.18 Al2O3) +(0.65 Fe2O3) If MgO is above 2 % LSF = 100( CaO – free CaO+1.5 MgO) (2.85 SiO2) + ( 1.18 Al2O3) +(0.65 Fe2O3) 95 – harder to burn, tendency to high free lime & C3S clinker , high early strength high fuel consumption < 95 , easy to burn , excess coating , excess liquid phase , possible brick infiltration reduced cement strength , low free lime acceptable standard deviation = 1.2
  12. 12. Raw meal residue Depends upon the Mineralogy , ie Calcite or quartz 90 mic = 8 – 15 % 212 mic = 0.5 – 3 %
  13. 13. time Variation from mines Variation After pre blending Variation after Raw milling Variation in quality control Set point
  14. 14. Auto sampler position - 20 mm
  15. 15. Liter weight
  16. 16. . Rapid burning ( short burning zone ) and rapid cooling of clinker improves the clinker quality. smaller C3S crystals with micro cracks)
  17. 17. Slow burning Fast burning
  18. 18. C3S Clinker when it is quenched in cooler it creates micro cracks which needs less energy for comminution during grinding. C3S Clinker cooling C2S
  19. 19. Reactions during clinker cooling Resorption of alite Liquid phase + C3S C2S + C3A + C2(A,F) Decomposition of alite very slow cooling reducing conditions C3S C2S + CaO Crystallization of liquid phase Slow cooling: large crystals – improved reactivity MgO crystals grow on cooling (periclase)
  20. 20. Properties of cement
  21. 21. • Portland cement • Portland pozzolana cement • Portland slag cement • Sulfate resistant cement • Oil well cement • Rapid hardening cement • White cement
  22. 22. Cement quality tests • Setting time • Compressive strength (mortar) • Modulus of rupture ( bending strength) • Fineness( blaine or Particle size distribution) • Expansion ( Le Chatelier & Auto clave) ( soundness) • Chemical analysis
  23. 23. X-4.0(100- X) /100 < 35% 3.03.03.0Insoluble residue % (max) 0.8 - 1.02 0.8 - 1.02 0.66 - 1.02 LSF CaO- 0.7 SO3/(2.8S+1.2A+0.65F) PPC53S53 Gr43 Gr specifications 5.04.04.05.0LOI 3.03.03.03.0SO3 % max 6.05.06.06.0Magnesia ,MgO %,max 0.050.100.10Cl max > 45C3S 10.0----C3A max BIS specifications for various grades of cement
  24. 24. 1051010.0Soundness ,LeChat expansion , (mm) max 30/60060/60030/60030/600Setting time, initial ( min) / final (max) , minutes 300.0370.0225.0225.0Fineness sqm /kg , min 162727233 days+/_ 1 hr Compressive strength, Mpa , min 0.80.80.80.8Soundness, Autoclave % 0.15Drying shrinkage 3353534328 days +/ - 4 hrs 2237.533337 Days +/_ 2 hrs
  25. 25. Blaine apparatus air permeability test
  26. 26. (Part - 5) Determination of Initial and Final Setting Times4031 (Part-5) Early stiffening – false set or flash set If less gypsum no gypsum flash set occurs If cement temperature > 130 deg c gypsum dehydrates and flash set occurs
  27. 27. Setting time ASTM specification
  28. 28. In concrete chemistry ettringite is a hexacalcium aluminate trisulfate hydrate, of general formula: (CaO)6(Al2O3)(SO3)3·32H2O or; CaO)3(Al2O3)(CaSO4)3·32H2O
  29. 29. Influencing parameters on Cement strength
  30. 30. 1 3 7 28 90 days Strength MPa C3S C2S C3A C4AF 60 0 20 30 40 50
  31. 31. = f (C3S) 28 7 3 1 MPa 70 60 50 40 30 20 10 40 45 50 55 60 65 % C3S
  32. 32. = f (Wk) 28 7 3 1 0 MPa 70 60 50 40 30 20 10 0 0.5 1.0 % Wk A 1% increase in LOI result in decrease in strength 1 day by 25 % 2 8days by 3 % and 90 days by 2 %
  33. 33. Cement strength is measured in 1 day, 3 days ,7days and 28 days Measurement compressive strength BIS 4031 (Part-8)1988(Part - 8) Determination of Compressive strength of hydraulic Cement
  34. 34. Compression testing 50*50mm
  35. 35. Compressive strength – influencing parameters Compressive strength 1 d 3 d 7 d 28 d Influencing Normal range 5 – 15 20 – 35 30 - 45 45 - 60 Parameters OPC C3S 45 – 65 % + + + + C3A 6 – 12 % + + + + Ks 0.2 – 1.5 % + + +/0/- - SO3 2 – 4 % +/0/- +/0/- +/0/- +/0/- Blaine 280 – 300 + + + + m2/kg Wk 0 - 0.3% - - - -
  36. 36. Quantitative rules of thumb C3S : 1 – 28 d : + 0.5 Mpa / % Ks ; 1 d : + 4 Mpa / % : 3 d : + 4 Mpa / % : 7 d : - 2 Mpa / % : 28 d : - 10 Mpa / % (SO3) tot : 1 - 28 d : - 5 Mpa / % from optimum Blaine : 1 d : + 0.04 Mpa / (m2/ kg) 3- 28 d : + 0.08 Mpa / (m2/ kg)
  37. 37. One day strength is contributed mainly by C3A , Soluble alkalies, and C3S 3 day is contributed mainly by C3S 7 days strength is contributed by mainly C3S 28 days strength is mainly contributed by C2S Apart from the above cement strength is enhanced by higher fineness of cement Less C3S crystal size achieved by rapid burning and quenching the clinker in cooler Higher fineness of rawmeal also reduces the crystal size of clinker minerals , ie ., C3S & C2S which enhances the hydraulic reactivity Cement strength – influencing parameters
  38. 38. Wk , prehydration of clinker Prehydration of clinker minerals can occur 1. As a result of incorrect internal water cooling in cement mill 2. when storing too hot cement in a silo 3. When clinker and especially cement is exposed to humidity Please note: If clinker has more soluble alkalis and sulfates it is highly hygroscopic especially when pet coke is fired. In cement silos they form Syngenite , K2SO4.2 CaSO4. H2O which forms lumps and block the cement silos. Hence venting is must to evacuate moisture and silo cleaning. cements having soluble alkalis and sulfates preferably packed in paper bags to avoid depletion of strength.
  39. 39. Thumb rule formulae for prediction of strength FLS predicted the formula for cement ground to 300 kgs/ m2 With 4 % gypsum strength, d28 = 52 - 10.( Ks) + 0.15.(C3S) The content of soluble alkalis Ks is dependent on the total alkali content and SO3 content in clinker. As per Knofel it is F 28 = (3*C3S)+ (2*C2S) + C3A – C4AF N / mm2 Strength prediction for 3 d = 97 + 35.8 Ma + 38.1K2SO4 + 28.7 Ms – 1.3 C3S Kg/ cm2 7 d = 300 + 13.4 Ms + 2.8 C2S + 56.1 Ma – 15.4 K2SO4 + 15.5 Na2O 28 d = 490 – 55.3 K2SO4 + 1.3 C3S (or) = 490 – 86 K2O + 2 C3S – 26 Na2O
  40. 40. Influence of fineness on cement strength For cements with the same specific surface the increase of the uniformity factor results in increase of strength of all ages. 1. The specific surface , the percentage of fractions 3- 32 mm and the uniformity factor n really influences the development of cement strength. The influence of 3 - 32 mm fraction and the uniformity factor is higher in cement with higher in specific surface ( > 3400 cm2/ g) 2. The fractions with particle size less than 3 mm contributes only to early strength while the fraction with particle size more than 24 mm influences strength development significantly. 3. While the fractions 3 – 16 mm and 16 – 32 mm seems to be more significant factor for specific surface 3500 – 4000 cm2/ g) . This is relevant only if the granulometric distribution is continuous and steep. 4. The optimistic granulometric distribution of a cement is a continuous and steep ( with high uniformity factor) distribution with a high (65 %) content in 3 – 32 mm fraction and specifically in 16 - 24 mm fraction and low content of fine particles ( < 3 mm , 10 % ) and specific surface of 2500 – 3000 cm2/ g according to Blaine.( high efficiency separator and grinding media distribution plays significantly here)
  41. 41. Properties of cement minerals Characteristics C3S C2S C3A C4AF Setting quick slow rapid nil Hydration rapid slow rapid nil 3 days heat 1.1 cal / g 0.4 cal / g 2 cal / g nil liberation Early strength high upto low upto not much nil Contribution 14 days 14 days beyond one day Late strength less later high later nil nil contribution Resistance to moderate high poor high Chemical attack Drying shrinkage nil low nil nil
  42. 42. Measurement of expansion for free lime ( IS 4031 Part3 -1988 Expansion due to free CaO=< 10 mm
  43. 43. Auto clave test for expansion of cement (Part - 3) Determination of Soundness 198 8 4031 (Part-3) 25*25*282mm Expansion limit < 0.8mm
  44. 44. Autoclave Calorie meter
  45. 45. Tube samplers for bulk cement
  46. 46. MgO Crystals Or Periclase
  47. 47. Free lime clusters
  48. 48. Problems and solutions 1. Grinding problems a) False set lower cement mill temperature add less gypsum add part anhydrite b) reduced strength high mill temperature less water cooling correct water cooling 2. Silo storage a) False set short storage time cooling of cement < 70 deg c b) reduced strength increase gypsum dehydration in mill c) lump formation and add less gypsum, use partly silo blockage (syngenite anhydrate , decrease K2O content formation, K2SO4.2CaSO4.H2O to avoid the formation of Syngenite Problems solutions
  49. 49. 3 ) Bag storage a. reduced strength short storage time b. lump formation add TEA during grinding (tri ethanal amine) add hydrophobic agents c. crust formation plastic coated bags d. abnormal setting plastic covering pallets
  50. 50. quality Process Quality is a set point and process is variable Right
  51. 51. Process quality Process is a set point and quality is variable wrong
  52. 52. Thanks you for your kind attention And spending your valuable business hours K.P.PRADEEP KUMAR Sr.GM Operation Karikkali works Chettinad Cements Ltd

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