Biomedical Engineering Reference
In-Depth Information
where
A
is the energy consumption.
D
1
and
D
2
are particle size of the feed and
discharge material, respectively.
Q
is a constant.
②
The volume hypothesis, proposed in 1885 by Germany's Kick, supposed that
when geometry similar to the material was crushed into products with a similar
geometry, the energy consumption was proportional to the volume or weight of
the broken block. The relationship was expressed using the following formula:
log
D
1
D
n
A D C
where
A
is the energy consumption.
D
1
and
D
n
are the particle size of the initial
feed and final discharge, respectively.
C
is a constant.
③
The cracks hypothesis, proposed in 1952 by Bond of the United States, suggested
that when particles with a size of
D
1
were crushed into a particle with size of
D
2
,
the energy consumption can be expressed as follows:
D
1=2
2
D
1=2
1
A D K
:
where
K
is a constant; Bond replaced it with 10 Wi. Wi is commonly known
as the Bond index. It is a parameter reflecting property resisting crushing and
abrasion. The crack hypothesis also interprets
D
as a measure of crack length of
the ruptured block. Therefore, crush energy consumption is also proportional to
the crack length.
These three hypotheses have limitations in application. The area hypothesis is
more suitable for grinding operations with a particle size 0.01-1 mm. The volume
hypothesis is more suitable for coarse crushing and medium crushing with a particle
size greater than 10 mm. The cracks hypothesis is between them and is suitable for
a more extensive range, from medium crushing to rough grinding operations.
There are still some other physical processing methods, such as steam explosion,
microwave and ultrasonic, radiation, and freezing methods; and chemical processing
methods, such as alkali treatment, solvent treatment, organic solvent treatment,
dilute acid treatment, oxidizing treatment, and supercritical extraction. However,
there is no mature model currently to analyze the consumption of energy and
chemical materials, but it could be calculated according to the consumption per
unit of product. Greenhouse gas produced by these treatment methods could be
calculated by referring to the Revised 1996 IPCC (Intergovernmental Panel on
Climate Change) Guidelines for National Greenhouse Gas Inventories, in which
greenhouse gas emissions from solvent used in a production process are included.
11.1.5.3
Research Methods for Products in the Primary Refining
Process [
20
]
According to the purpose of primary refining, different research methods are
required to analyze the final product. The purpose of primary refining can be
