This is my solution to Problem Number 2 from Chapter 11 of Fundamentals of Particle Technology by Holdich. Hope it helped. E-mail me if you have questions or corrections at vic_zhou14@yahoo.com.ph. :)
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Crushing and Classification number 2 solution (Particle Technology by Holdich)
1. Canja, Bobby T.
ChE 65 A
BS ChE 5
February 28, 2013
Chapter 11 Crushing and Classification
below
k
f
p
q
C
k-q
M
2. By doing material balance in certain sections of the diagram, the following equations are
obtained.
(1)
(2)
(3)
(4)
Manipulating (4):
(5)
Substituting (3) to (1):
(6)
Substituting (6) to (5):
(7)
Manipulating (7):
(8)
Given from the problem:
C=
0.1
0
0
0
0
0.3
0
0
0
0
0.5
0
0
0
0
0.7
For the size distribution in the feed rate, 4 grades are assumed for the classifications of the
particle sizes, namely:
Grade
1
2
3
4
Size (亮m)
1000 to 750
750 to 500
500 to 250
<250
3. The size distribution of the particles in the feed with respect to each grade is obtained by
subtracting the number of undersize in a corresponding particle diameter to the undersize
percentage of the next smaller particle size diameter. The feed matrix in terms of mass flow rate
is therefore:
f=
0.15
0.61
0.14
0.10
f=
0.75
3.05
0.7
0.5
X
5 tons/hour
The mill matrix is derived with the use of the breakage function unction
where
y is the lower boundary and x is the mean particle size within a certain grade.
M=
0.176
0.358
0.267
0.199
0
0.287
0.427
0.286
0
0
0.448
0.552
0
0
0
1
There is also an identity function which when multiplied by a certain matrix will yield the value of
the matrix multiplied to this type of matrix given by:
I=
1
0
0
0
0
1
0
0
0
1
0
0
0
0
1
The I C matrix is just the difference of each elements in matrix I and C.
IC=
0.9
0
0
0
0
0.7
0
0
0
0
0.5
0
0
0
0
0.3
4. Multiplying the matrix above the matrix of the feed yields:
0.675
2.135
0.350
0.150
(I C) {f} =
Performing operations of matrix for the rest of the terms given in the equation, yields the
following matrices.
(I C)M =
0.158
0.251
0.134
0.060
0
0.201
0.214
0.086
0
0
0.224
0.165
0
0
0
0.300
I - (I C)M =
0.842
-0.251
-0.134
-0.06
0
0.799
-0.2135
-0.086
0
0
0.776
-0.165
0
0
0
0.7
Let
so that
; where
The cofactor matrix of H is obtained by using the formula
for each of the element
of matrix H where m = the minor of an element, which is the determinant of the matrix that
excludes the row and column where the element is located.
The cofactor matrix, as obtained by applying the formula in each element is:
e=
0.434
0
0
0
0.136
0.457
0
0
0.086
0.126
0.471
0
0.08
0.086
0.111
0.522
0
0.457
0.126
0.086
0
0
0.471
0.111
0
0
0
0.522
The transpose of this matrix is:
et =
0.434
0.136
0.086
0.08
5. From the original equation of inverse matrix,
H-1 =
=
1.189
0.373
0.236
0.219
0
1.252
0.345
0.236
0
0
1.29
0.304
0
0
0
1.43
1.189
0.373
0.236
0.219
0
1.252
0.345
0.236
0
0
1.29
0.304
0
0
0
1.43
From equation (8):
{k-q} =
0.675
2.135
0.350
0.150
Thus,
{k-q} =
0.803
2.925
1.347
0.973
tons per hour
The size distribution in percentage in the coarse cut from the classifier is:
Grade Percentage
1
13.28 %
2
48.36 %
3
22.27 %
4
16.09 %
The total flow rate is 6.048 tons/hour.