World Grain - November 2018 - 76

MILLING OPERATIONS

Utilizing granulation curves
Predicting expected distribution of ground stock
a key to maintaining proper mill balance
by Jeff Gwirtz

In my previous article in the September 2018 issue of World
Grain, the procedure to measure break release was presented
as part of a series of articles to discuss in greater detail the
development and utilization of the three tools mentioned in
Mark Fowler's article, "Balancing the mill," in the February
2012 issue of World Grain.
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to the various parts of the milling system, as determined by
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ground stock must be kept within the parameters of the system
design to maximize mill performance as part of the balancing
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granulation curve builds upon knowledge revealed by measuring break release in that it further describes the particle size
distribution of the released material.
FACTORS IMPACTING THE GRANULATION CURVE
Mill balance and product distribution variability is endemic to
any processing system and performance measures. In reviewing six categories - Mother Nature, Mankind, Materials,
Method, Measurement and Machines - some factors that inÀXHQFHJUDQXODWLRQSUR¿OHYDULDWLRQVDUHLGHQWL¿HGLQ7DEOH
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graphic representation of the measured percentage of cumulative material held over a given size screen opening.
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loading changes due to alternative screen selection via visual inspection or linear interpolation.
76

Table 1. Category of factors and influencing granulation profile
Category

Factors

Mother Nature

Temperature, relative humidity

Mankind

Improper water setting during tempering,
improper roll corrugation selection/installation

Material

Kernel size, kernel hardness, wheat variety

Measurement
Machines
Method

Scale weights, screen identification, sifting time
Roll wear, belt slip, roll setting
Sampling collection, screen selection,
calculation

Table 2. Granulation curve calculations
Screen

Microns

Grams

%

∑%

24 SS

869

59

12.0

12.0

28 SS

716

67

13.6

25.7

34 SS

581

54

10.9

36.6

46 SS

437

86

17.5

54.1

62 SS

308

71

14.4

68.5

94 SS

180

74

15.1

83.6

165 SS

107

59

12.0

95.6

PAN

0

22

4.4

100.0

490

100

Initial sample was 500 grams, therefore recovery is 98%
November 2018 / World Grain / www.World-Grain.com
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World Grain - November 2018

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