512 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
particles to find their paths to contact the screening sur-
faces and then pass through as undersize product. It, how-
ever, does not help the screening process if the particles
are overly-stratified and end up airborne most of the time.
Derrick’s high speed low amplitude screens are proven bet-
ter suited for dry, fine particle screening than traditional
low frequency high amplitude dry coarse screens.
Temperature and Chemical Compatibility
Material temperature and chemical compatibility are piv-
otal in selecting and optimizing screening performance.
The temperature of materials influences their structural
stability, impacting screening efficiency. Compatibility
with specific chemicals prevents degradation and reactions
during the screening process. Optimal material selection
ensures durability, preventing deformities and enhancing
overall performance in screening applications across diverse
industrial settings.
We also need to consider desired separation size, prod-
uct specifications and any machine layout requirements,
including headroom constraints and maintenance space
required for different fine screening technologies. Tailoring
the screening process to meet specific separation criteria and
accommodate layout constraints ensures precision and effi-
ciency. Addressing product specifications further refines the
selection, aligning the technology with desired outcomes. A
holistic approach, encompassing material attributes, sepa-
ration criteria, and spatial considerations, is essential for
optimizing fine screening technologies in diverse industrial
applications.
SCREENING PERFORMANCE
EVALUATION: EFFICIENCY AND
PARTITION CURVE
The factors that affect the screen classification efficiency
mainly include the following aspects: the material prop-
erties (the solid content, pulp properties, particle size and
density distribution, particle shape, and other factors), the
screen surface parameters (panel opening, opening geom-
etry, opening area, panel material, anti-blinding design,
and so on), the screen motion (‘G’ force, vibration veloc-
ity, vibration amplitude, and frequency), and other relevant
factors. For the evaluation of any classification devices, it
is often to consider the classification efficiency, capacity,
energy consumption and operation life.
Screening Efficiency
A screening machine separates a feed stream into oversize
and undersize products. A convenient method to determine
the effectiveness of this separation is to calculate efficiency.
In practical terms, efficiency refers to the amount of mate-
rial that was correctly placed, often expressed as a percent.
Three efficiency values may be calculated. Oversize
efficiency refers to the amount of oversize in the feed that
was directed to the oversize product stream. Similarly, the
amount of undersize in the feed that was placed in the
undersize product stream is the undersize efficiency. The
overall efficiency refers to the total amount of correctly
placed material. Efficiency, as well as the product weight
splits, is calculated from the particle size distribution of the
feed and products.
At the desired separation size, the following data is
required for the calculation:
A =percent of oversize in the feed
B =percent of undersize in the feed (100 – A)
C =percent of oversize (coarse) in the oversize
product
D =percent of undersize (fines) in the undersize
product. The weight splits and efficiency values
are calculated as follows
U =Undersize weight (percent) =C D
C A 100 100 +-
-
O =Oversize weight (percent) =100 – U
E =Undersize efficiency =*
B
U D
E =Oversize efficiency =*
A
O C
E =Overall efficiency =**U D O C
100
+
CASE STUDIES
Dry Sizing Silica at 230 Mesh
Silica is an important resource for the manufacture of glass,
quartz glass, fiber optics, electronics industry, optical instru-
ments, handicrafts and refractory products. Silica producers
are now often required to provide products with very strict
requirement on the particle size distribution. An American
Silica producer sent samples to Derrick Corporation for
industrial-scale testing to evaluate the effect of Derrick
High Frequency dry sizing machines. The testing data is
shown in Table 1.
The screening efficiency calculation shows that the
undersize efficiency is 83.91%, oversize efficiency is
97.99%, and overall efficiency is 92.03% for test 1. For test
2, the undersize efficiency is 86.46%, oversize efficiency is
97.61%, and overall efficiency is 91.18%. It is clear that
Derrick high frequency dry screen can effectively screen/
size silica samples at fine panel opening with high accuracy
and high efficiency.
particles to find their paths to contact the screening sur-
faces and then pass through as undersize product. It, how-
ever, does not help the screening process if the particles
are overly-stratified and end up airborne most of the time.
Derrick’s high speed low amplitude screens are proven bet-
ter suited for dry, fine particle screening than traditional
low frequency high amplitude dry coarse screens.
Temperature and Chemical Compatibility
Material temperature and chemical compatibility are piv-
otal in selecting and optimizing screening performance.
The temperature of materials influences their structural
stability, impacting screening efficiency. Compatibility
with specific chemicals prevents degradation and reactions
during the screening process. Optimal material selection
ensures durability, preventing deformities and enhancing
overall performance in screening applications across diverse
industrial settings.
We also need to consider desired separation size, prod-
uct specifications and any machine layout requirements,
including headroom constraints and maintenance space
required for different fine screening technologies. Tailoring
the screening process to meet specific separation criteria and
accommodate layout constraints ensures precision and effi-
ciency. Addressing product specifications further refines the
selection, aligning the technology with desired outcomes. A
holistic approach, encompassing material attributes, sepa-
ration criteria, and spatial considerations, is essential for
optimizing fine screening technologies in diverse industrial
applications.
SCREENING PERFORMANCE
EVALUATION: EFFICIENCY AND
PARTITION CURVE
The factors that affect the screen classification efficiency
mainly include the following aspects: the material prop-
erties (the solid content, pulp properties, particle size and
density distribution, particle shape, and other factors), the
screen surface parameters (panel opening, opening geom-
etry, opening area, panel material, anti-blinding design,
and so on), the screen motion (‘G’ force, vibration veloc-
ity, vibration amplitude, and frequency), and other relevant
factors. For the evaluation of any classification devices, it
is often to consider the classification efficiency, capacity,
energy consumption and operation life.
Screening Efficiency
A screening machine separates a feed stream into oversize
and undersize products. A convenient method to determine
the effectiveness of this separation is to calculate efficiency.
In practical terms, efficiency refers to the amount of mate-
rial that was correctly placed, often expressed as a percent.
Three efficiency values may be calculated. Oversize
efficiency refers to the amount of oversize in the feed that
was directed to the oversize product stream. Similarly, the
amount of undersize in the feed that was placed in the
undersize product stream is the undersize efficiency. The
overall efficiency refers to the total amount of correctly
placed material. Efficiency, as well as the product weight
splits, is calculated from the particle size distribution of the
feed and products.
At the desired separation size, the following data is
required for the calculation:
A =percent of oversize in the feed
B =percent of undersize in the feed (100 – A)
C =percent of oversize (coarse) in the oversize
product
D =percent of undersize (fines) in the undersize
product. The weight splits and efficiency values
are calculated as follows
U =Undersize weight (percent) =C D
C A 100 100 +-
-
O =Oversize weight (percent) =100 – U
E =Undersize efficiency =*
B
U D
E =Oversize efficiency =*
A
O C
E =Overall efficiency =**U D O C
100
+
CASE STUDIES
Dry Sizing Silica at 230 Mesh
Silica is an important resource for the manufacture of glass,
quartz glass, fiber optics, electronics industry, optical instru-
ments, handicrafts and refractory products. Silica producers
are now often required to provide products with very strict
requirement on the particle size distribution. An American
Silica producer sent samples to Derrick Corporation for
industrial-scale testing to evaluate the effect of Derrick
High Frequency dry sizing machines. The testing data is
shown in Table 1.
The screening efficiency calculation shows that the
undersize efficiency is 83.91%, oversize efficiency is
97.99%, and overall efficiency is 92.03% for test 1. For test
2, the undersize efficiency is 86.46%, oversize efficiency is
97.61%, and overall efficiency is 91.18%. It is clear that
Derrick high frequency dry screen can effectively screen/
size silica samples at fine panel opening with high accuracy
and high efficiency.