CHAPT-03.PDF

Mill Material Balance

The Extractions III -1

CHAPTER III

THE EXTRACTIONS

Sugar is categorized the kind of sweetener produced through the processing of raw material, such

as sugar cane, beet, coconut, different kinds of palm trees and stevia leaves as well.

We will discuss sugar; the sweetener that mainly produced by the sugar factories processing

sugar cane as the raw material into a sweetener called crystal sugar.

Sugar cane is one among the other plants that richly consist of sugar (saccharose).

Looking to the materials consisting in sugar cane, they could be grouped into two portions, i.e.

the juice and the fiber. The same grouping applies for the component if they are seen from the

physical terms, where the sweetener (saccharose) inhibits the cane juice.

To optimally extract the saccharose from the sugar cane, a lot of separation works have to be

implemented especially separating the non-sugar content from the sugar juice.

Indeed most of the works applied in sugar factory were mainly separating works, such as

separating cane juice from the fiber containing the cane, separating the water content from the

cane juice, separating the color, separating viscous material from the crystal containing in the

massecuite and so on.

The first phase of such a work is to separate the cane juice from its fiber, and this is to be done

with the help of certain equipment such as the mill, the diffuser, cane separator, screw press

and the others as well.

In the case of separating cane juice from its fiber which containing the sugar cane with the use of

mill, such as normally done in cane sugar factories; we knew the term of extraction.

The sugar cane is extracted to separate its juice from the fiber. If good extraction is expected, we

have to put additional water as imbibition / maceration to dilute the saccharose stickled around

the fiber cells, makes it easier to be separated or extracted.

Because cane juice is considered to consist of water and brix, then sugar cane as physically seen

is considered as to consist of juice and fiber. Further sugar cane also known as to consist of

water, brix and fiber, while the sugar content of the cane is normally expressed by the value of its

polarization (%pol).

Based upon the above descriptions, then we have to know the basic measure of extraction, which

in term of milling there should be at least 3 (three) parameters:

Juice extraction

Brix extraction (HPB)

Sugar extraction (HPG)

The juice extraction, is the result of division between the extracted juice and the juice containing

in the incoming / original material.



The Brix extraction, is the result of division between the extracted Brix and the total Brix

containing in the incoming / original material.

The sugar extraction, is the result of division between the extracted sugar (polarization) and the

sugar containing in the incoming / original material.

The expression of extraction therefore can be in fraction or in percentage.

Well have further the overview of extraction for the following tandem consisting of 4 units of

mill.

The system shown above called the cane juice mill extraction with compound imbibition.

In order to determine the rate of extraction, we have to calculate the amount of cane juice

extracted by each mill in the tandem.

Lets see at mill#1:

Wim1 = the weight of incoming material (cane),

Wb1 = the weight of bagasse produced,

Wej1 = the weight of juice extracted;

then: Wim1 = Wb1 + Wej1

hence: W ej1 = Wim1 - Wb1 ............................................. (a)

And then at mill#2:

Wim2 = the weight of incoming material,


Wej2 = the weight of juice extracted;

then: Wim2 = Wb2 + Wej2 ............................................. (b)

hence: Wej2 = Wim2 - Wb2 .......................................... (c)

ej1 ej2

ej3

ej4

b1 b2 b3

b4 water

ej4 ej3

mj

cane Mill.I Mill.II Mill.III Mill.IV



Then at mill#3:

But back to equation (b):

Wim2 = Wb2 + Wej2,

also: Wim2 = Wb1 + Wej3

hence: Wej3 = Wb2 + Wej2 - Wb1 .................................... (d)

If: Wim3 = the weight of incoming material,


Wej3 = the weight of juice extracted,

Wej4 = the weight of juice extracted by mill#4;

then: Wim3 = Wb3 + Wej3

also: Wim3 = Wb2 + Wej4

hence: Wej4 = Wb3 + Wej3 - Wb2 .................................... (e)

Weve been trying to define all the formulas of juice extraction in each mill, but only the weights

of juice extracted by mill#1 and mill#2, which could be detected so far.

The weight of juice extracted by mill#1 that is Wej1 in the equation (a), could be calculated by the

following Brix method:

bmj - bj2 Wej1 = Wmj bj1 - bj2

Where the above formula describes:

Wmj = the weight of mixed juice which is known through its weighing or measured,

bmj = the Brix degree of mixed juice,

bj1 = the Brix degree of mill#1 juice,

bj2 = the Brix degree of mill#2 juice;

All the values of Brix degree were the results of analysis.

Hence, the weight of bagasse produced by mill#1 that is Wb1 can be calculated, because Wim1

that is the weight of cane crushed was known during its weighing.

The weight of juice extracted by mill#2 is then:

Wej2 = Wmj - Wej1

For the moment we can not calculate the weights of juice extracted by mill#3 {Wej3 on equation

(d)} and the juice extracted by mill#4 {Wej4 on equation (e)}, because the weights of bagasse

produced by mill#2 and mill#3 are not known.

All unknown items will be defined by the new system of calculation for a complete mill material

balance, especially the formula for the weight of bagasse exhausted by the respective mill after

mill#1 in the tandem.

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