XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2055
Rotational Frequency
The test of f was conducted under the conditions of P
0.03 MPa, andV 25 ml/s, and the test results are shown in
Figure 9.With the increase of f, the ash content of clean coal
decreases from 4.39 to 3.20%, and the corresponding yield
decreases gradually from 78.06 to 50.46%, while the vitrin-
ite content in clean coal increases gradually from 55.24 to
70.00%. When the f increases, the centrifugal force suf-
fered by the particles in the sorting area increases. So more
particles settling in the rifling circle to enter into underflow,
which decreases the yield and ash of the clean coal. In addi-
tion, the vitrinite is more likely to be enriched in the low
density class, and the vitrinite content in the clean coal is
improved.
With the increase of f, the enrichment ratio of vitrinite
gradually increases from 0.98 to 1.24, and the recovery rate
gradually decreases from 76.28 to 62.48%. Among them,
the enrichment ratio of vitrinite and the change trend of
vitrinite content are consistent, and its increase is attrib-
uted to the increase of vitrinite content. The recovery rate is
related to the vitrinite content and clean coal yield. With the
increase of f, the high density particles are more enriched in
the rifling circle to become tailing coal, the total amount of
overflow product decreases, but the proportion of low den-
sity particles in the overflow product is relatively improved,
and the vitrinite content increases. But the magnitude of
increase in the vitrinite content is not as fast as the decrease
in the overflow product yield, which results in the recovery
rate of vitrinite always decrease.
Backwash Water Pressure
The test of Pwas conducted under the conditions of f
35 Hz, and V 25 ml/s, and the test results are shown in
Figure 10. With the increase of P, the ash content of clean
coal increases gradually, from 3.13 to 4.72%, and the clean
coal yield also increases gradually from 45.19 to 75.46%,
while the vitrinite content in clean coal decreases gradually,
from 69.75 to 54.87%.When Pincreases, the settling resis-
tance to particles in the sorting zone increases, resulting in
an increase in the clean coal yield and ash content. When
the sorting bed looseness is appropriate, the increase in
backwash water pressure will cause high density particles to
increase the possibility of becoming overflow, resulting in
a decrease in the vitrinite content in the overflow product.
With the increase of P, the enrichment ratio of vitrin-
ite gradually decreases from 1.23 to 0.97, and the recovery
ratio gradually increases from 55.76 to 73.24%. Among
them, the enrichment ratio is consistent with the chang-
ing trend of vitrinite content. Vitrinite recovery is cor-
related with vitrinite content and clean coal yield. With
the increase of P, the settling resistance of particles in the
sorting area becomes larger, resulting in high-density par-
ticles are difficult to overcome the pressure of the backwash
water to deposit in the comeback circle. High-density grade
material contains a large number of inertinite and miner-
als, which will result in the decrease of vitrinite content
of the overflow product. Due to the increase in backwash
water pressure, the clean coal yield increases, resulting in an
increase in the recovery rate of vitrinite.
Figure 9. Variation of sorting and evaluation indicators with rotational frequency
Rotational Frequency
The test of f was conducted under the conditions of P
0.03 MPa, andV 25 ml/s, and the test results are shown in
Figure 9.With the increase of f, the ash content of clean coal
decreases from 4.39 to 3.20%, and the corresponding yield
decreases gradually from 78.06 to 50.46%, while the vitrin-
ite content in clean coal increases gradually from 55.24 to
70.00%. When the f increases, the centrifugal force suf-
fered by the particles in the sorting area increases. So more
particles settling in the rifling circle to enter into underflow,
which decreases the yield and ash of the clean coal. In addi-
tion, the vitrinite is more likely to be enriched in the low
density class, and the vitrinite content in the clean coal is
improved.
With the increase of f, the enrichment ratio of vitrinite
gradually increases from 0.98 to 1.24, and the recovery rate
gradually decreases from 76.28 to 62.48%. Among them,
the enrichment ratio of vitrinite and the change trend of
vitrinite content are consistent, and its increase is attrib-
uted to the increase of vitrinite content. The recovery rate is
related to the vitrinite content and clean coal yield. With the
increase of f, the high density particles are more enriched in
the rifling circle to become tailing coal, the total amount of
overflow product decreases, but the proportion of low den-
sity particles in the overflow product is relatively improved,
and the vitrinite content increases. But the magnitude of
increase in the vitrinite content is not as fast as the decrease
in the overflow product yield, which results in the recovery
rate of vitrinite always decrease.
Backwash Water Pressure
The test of Pwas conducted under the conditions of f
35 Hz, and V 25 ml/s, and the test results are shown in
Figure 10. With the increase of P, the ash content of clean
coal increases gradually, from 3.13 to 4.72%, and the clean
coal yield also increases gradually from 45.19 to 75.46%,
while the vitrinite content in clean coal decreases gradually,
from 69.75 to 54.87%.When Pincreases, the settling resis-
tance to particles in the sorting zone increases, resulting in
an increase in the clean coal yield and ash content. When
the sorting bed looseness is appropriate, the increase in
backwash water pressure will cause high density particles to
increase the possibility of becoming overflow, resulting in
a decrease in the vitrinite content in the overflow product.
With the increase of P, the enrichment ratio of vitrin-
ite gradually decreases from 1.23 to 0.97, and the recovery
ratio gradually increases from 55.76 to 73.24%. Among
them, the enrichment ratio is consistent with the chang-
ing trend of vitrinite content. Vitrinite recovery is cor-
related with vitrinite content and clean coal yield. With
the increase of P, the settling resistance of particles in the
sorting area becomes larger, resulting in high-density par-
ticles are difficult to overcome the pressure of the backwash
water to deposit in the comeback circle. High-density grade
material contains a large number of inertinite and miner-
als, which will result in the decrease of vitrinite content
of the overflow product. Due to the increase in backwash
water pressure, the clean coal yield increases, resulting in an
increase in the recovery rate of vitrinite.
Figure 9. Variation of sorting and evaluation indicators with rotational frequency