hydro cyclone
DESCRIPTION
This experiment is conducted to exposed student to:1. Introducing the hydrocyclone as one of the important tools in the classification processof mineral processing industry.2. Learn the operation of the hydrocyclone in lab scale and see the components involvedthat affects the efficiency of the hydrocyclone.3. Determine the operational parameters and geometry that affect the performance ofhydrocyclone efficiency.4. Studies about the particle size distribution on the sample of feed, overflow andunderflow.TRANSCRIPT
HYDROCYCLONE By Muhammad Zulqayyim Bin Noor Azizul
School of Material and Mineral Resources Engineering, Universiti Sains Malaysia ABSTRACT
Hydrocyclone is a device to classify, separate or sort particles in a liquid suspension based on ratio of their centrifugal force to fluid resistance. Hydrocyclone is simple and high capacity equipment relative to its size. Hydrocyclone is suitable for particles in very fine size separation, normally below 75 micron size. This experiment shows a sample of slurry is feed into a hydrocyclone and the slurry will create a swilling motion inside the hydrocyclone and eventually divided the slurry into overflow and underflow. Corse particle will be in the underflow while fine particle in the overflow product. This experiment is conducted at two different pressures which are 5 psi and 10 psi to compare the efficiency of the hydrocyclone according to pressure given at the feed. The experiment shows that the 50% size distribution of particle in overflow of 10 psi sample is higher than 5 psi. So, the experiment is in line with the theory which says that separation at higher pressure will be more effective. INTRODUCTION
A hydrocyclone is a static device that applies centrifugal force to a liquid mixture so as to promote the separation of heavy and light components. Analytical hydrocyclone consist of a conically shaped vessel, open at its apex, or underflow joined to a cylindrical section, which has tangential feed inlet. The top of the cylindrical section is closed with a plate though which passes an axially mounted overflow pipe. This pipe is extended into the body of the cyclone by a short, removable section known as vortex finder, which prevent short circulating of feed directly into the overflow.
Figure: Hydrocyclone
The hydrocyclone is a closed vessel designed to convert incoming liquid velocity into rotary motion. It does this by directing inflow tangentially near the top of a vertical cylinder. This spins the entire contents of the cylinder, creating centrifugal force in the liquid. The feed flow, which is a slurry of small particles, into liquid enters tangentially into the cyclone and is divided into underflow, which carries most of the solids, and overflow, which contacts most of the Liquid. The separation of solid from liquid depends on the particle size and particle density. Centrifugal force throws the particles out against the wall and they subsequently drop into the outlet hopper. Cyclone consists of vertical cylinder with conical bottom. The inlet point is near the top of the cylindrical portion. The particles separated are collected at the bottom.
In the operation of hydrocyclones, slurry is feed into a hydrocyclone under certain pressure through the inlet. Mineral particles that entering the hydrocyclone will be acted by two different forces acting on the contrary which are the centrifugal force and drag force:
a. Centrifugal force will act inwards. According to Stokes Law, the action of centrifugal force on the particles accelerates the rate of sedimentation of mineral particles. Therefore, the particles are being separated by the difference in size and gravity. Usually, coarse particles that settled quickly will move to the cyclone wall, where the velocity is low, and goes out through the opening under the apex of the flow. This particle is known as underflow sample.
b. By the action of drag force, the particles that have a low sedimentation rate, usually the fine size, will move to low pressure zone along the axis of the cyclone and will move up through the vortex finder. This particle is known as overflow sample. Hydrocyclones are also related to centrifuges in that both are intended to separate
heavies and lights by application of centrifugal force to liquids. The key difference is that hydrocyclones are passive separators capable of applying modest amounts of centrifugal force, whereas centrifuges are dynamic separators that are generally able to apply much more centrifugal force than hydrocyclones. Another key difference between hydrocyclones and centrifuges is cost. Centrifuges are expensive precision rotating machines that often need sophisticated control, whereas hydrocyclones have no moving parts and usually no controls at all so they are lower cost devices. OBJECTIVE
This experiment is conducted to exposed student to: 1. Introducing the hydrocyclone as one of the important tools in the classification process
of mineral processing industry. 2. Learn the operation of the hydrocyclone in lab scale and see the components involved
that affects the efficiency of the hydrocyclone. 3. Determine the operational parameters and geometry that affect the performance of
hydrocyclone efficiency. 4. Studies about the particle size distribution on the sample of feed, overflow and
underflow.
PROCEDURE
1. 1 kg of sample was given by lab assistant. 2. Hydrocyclone was clean by rinse with clean water and let to flow in close circuit. 3. Water was added into hydrocyclone rig until 20 mL to get 5% solid. 4. Water was let too flow in close circuit for a few minutes to get a consistent flow before
the test. 5. Sample was added into the rig thoroughly. 6. Pressure gauge was adjusted to 5 psi and let to flow for a few minutes. 7. Overflow and underflow rate was determined by using clock timer and flask stinging. 8. Pulp feed density, underflow and overflow sample was taken by using a basin in 2.8-‐2.9
seconds for particle size distribution analysis. 9. Step 6-‐8 was repeated by using pressure of 10 psi. 10. All samples were dried in oven and particle size distribution was determined by using
particle size analyzer. RESULT
𝑃𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑆𝑜𝑙𝑖𝑑 =𝑊𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑠𝑜𝑙𝑖𝑑
𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑠𝑜𝑙𝑢𝑡𝑖𝑜𝑛 × 100%
= ! !"!" !
× 100%
= 5 % 𝑠𝑜𝑙𝑖𝑑
Table: Operation setting of hydrocyclone
Pressure (psi) Sample Time to Fill Container (s)
Mass (kg)
Flow Rate (t/h)
Pulp Density (kg/m3)
5
Feed 3.24 1.18 1.31 1180
Overflow 4.02 1.12 1.00 1120
Underflow 20.17 1.44 0.26 1440
10
Feed 7.90 1.14 0.52 1140
Overflow 3.57 1.06 1.06 1060
Underflow 17.85 1.20 0.24 1200
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑖𝑙𝑙𝑒𝑑 𝑓𝑙𝑎𝑠𝑘 𝑠𝑡𝑖𝑛𝑔𝑖𝑛𝑔𝑇𝑖𝑚𝑒 𝑡𝑜 𝑓𝑖𝑙𝑙𝑒𝑑 𝑓𝑙𝑎𝑠𝑘 𝑠𝑡𝑖𝑛𝑔𝑖𝑛𝑔
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =𝑀𝑎𝑠𝑠 𝑜𝑓 𝑓𝑖𝑙𝑙𝑒𝑑 𝑓𝑙𝑎𝑠𝑘 𝑠𝑡𝑖𝑛𝑖𝑛𝑔𝑉𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑓𝑙𝑎𝑠𝑘 𝑠𝑡𝑖𝑛𝑔𝑖𝑛𝑔
At pressure 5 psi; Feed
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =1.18 𝑘𝑔3.24 𝑠
×3600 𝑠1 ℎ
×1 𝑡
1000 𝑘𝑔
= 𝟏.𝟑𝟏 𝒕/𝒉
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =1.18 𝑘𝑔1 𝐿
× 1000 𝐿1 𝑚!
= 𝟏𝟏𝟖𝟎 𝒌𝒈/𝒎𝟑 Overflow
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =1.12 𝑘𝑔4.02 𝑠
×3600 𝑠1 ℎ
×1 𝑡
1000 𝑘𝑔
= 𝟏.𝟎𝟎 𝒕/𝒉
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =1.12 𝑘𝑔1 𝐿
× 1000 𝐿1 𝑚!
= 𝟏𝟏𝟐𝟎 𝒌𝒈/𝒎𝟑 Underflow
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =1.44 𝑘𝑔20.17 𝑠
×3600 𝑠1 ℎ
×1 𝑡
1000 𝑘𝑔
= 𝟎.𝟐𝟔 𝒕/𝒉
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =1.44 𝑘𝑔1 𝐿
× 1000 𝐿1 𝑚!
= 𝟏𝟒𝟒𝟎 𝒌𝒈/𝒎𝟑
At pressure 10 psi; Feed
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =1.14 𝑘𝑔7.90 𝑠
×3600 𝑠1 ℎ
×1 𝑡
1000 𝑘𝑔
= 𝟎.𝟓𝟐 𝒕/𝒉
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =1.14 𝑘𝑔1 𝐿
× 1000 𝐿1 𝑚!
= 𝟏𝟏𝟒𝟎 𝒌𝒈/𝒎𝟑 Overflow
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =1.06 𝑘𝑔3.57 𝑠
×3600 𝑠1 ℎ
×1 𝑡
1000 𝑘𝑔
= 𝟏.𝟎𝟔 𝒕/𝒉
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =1.06 𝑘𝑔1 𝐿
× 1000 𝐿1 𝑚!
= 𝟏𝟎𝟔𝟎 𝒌𝒈/𝒎𝟑
Underflow
𝐹𝑙𝑜𝑤 𝑅𝑎𝑡𝑒 =1.20 𝑘𝑔17.85 𝑠
×3600 𝑠1 ℎ
×1 𝑡
1000 𝑘𝑔
= 𝟎.𝟐𝟒 𝒕/𝒉
𝑃𝑢𝑙𝑝 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 =1.20 𝑘𝑔1 𝐿
× 1000 𝐿1 𝑚!
= 𝟏𝟐𝟎𝟎 𝒌𝒈/𝒎𝟑
Table: Cumulative Distribution of Particle Size
Size (micron)
Cumulative Distribution (%) 5 psi 10 psi
Feed Overflow Underflow Feed Overflow Underflow 0.18 1.97 2.27 0.95 1.39 1.82 0.98 0.22 2.72 3.22 1.32 1.92 2.52 1.36 0.26 3.37 4.10 1.65 2.38 3.14 1.69 0.30 3.94 4.92 1.95 2.79 3.69 1.98 0.36 4.74 6.03 2.37 3.35 4.46 2.39 0.44 5.74 7.36 2.90 4.07 5.44 2.90 0.52 6.73 8.54 3.42 4.81 6.41 3.40 0.62 8.04 9.86 4.08 5.80 7.70 4.06 0.74 9.75 11.33 4.90 7.13 9.37 4.92 0.86 11.59 12.79 5.75 8.60 11.18 5.84 1.00 13.81 14.57 6.74 10.41 13.39 6.95 1.20 16.94 17.31 8.06 13.01 16.56 8.50 1.50 21.42 21.64 9.84 16.77 21.17 10.66 1.80 25.71 25.93 11.38 20.30 25.60 12.65 2.10 29.98 30.11 12.80 23.68 29.99 14.52 2.50 35.64 35.79 14.61 27.97 35.80 16.93 3.00 42.34 43.18 16.71 32.92 42.78 19.74 3.60 49.49 51.79 18.96 38.14 50.34 22.79 4.20 55.49 59.09 20.89 42.58 56.69 25.45 5.00 62.10 66.44 23.12 47.56 63.54 28.57 6.00 68.77 72.70 25.62 52.70 70.24 32.03 7.20 75.26 78.02 28.48 57.82 76.61 35.87 8.60 81.33 83.12 31.66 62.82 82.58 40.09 10.20 86.75 88.18 34.68 67.34 87.96 44.32 12.20 91.75 93.19 37.08 71.27 92.96 48.40 14.60 95.76 97.18 38.61 74.10 96.92 51.90 17.40 98.49 99.46 41.20 76.49 99.29 55.90 20.60 99.79 100.00 48.69 80.10 100.00 62.82 24.60 100.00 100.00 64.96 86.67 100.00 75.30 29.40 100.00 100.00 85.28 94.46 100.00 89.84 35.00 100.00 100.00 100.00 100.00 100.00 100.00
Graph of Cumulative Distribution against Particle Size Distribution
Table: Size for which 50% of particle reported for each sample Size
Sample D50 (𝜇𝑚)
5 psi 10 psi Feed 3.65 5.47
Overflow 3.47 3.57 Underflow 20.92 13.30
DISCUSSION
Based on results that have been calculated, it can be show that the pulp density of underflow sample is decrease with the increase in pressure form 5 to 10 psi. This mean the amount of solid or % solid in sample is decrease as the pressure increase. Higher pressure will produce better efficiency as the larger centrifugal force created in the hydrocyclone. The centrifugal force created in the hydrocyclone is one of the parameter needed to control the efficiency of separation. Therefore, with higher pressure contribute to the feed will produce better separation.
In additional, by increasing the pressure supply, the efficiency of hydrocyclone can be increased too as proved by particle size distribution analysis on the samples. It can be concluded that the higher the pressure, the higher the efficiency of the hydrocyclone where more fine particle sample can be separated to vortex as overflow. Particle size distribution test show that the size for which 50% of particle reported in overflow for 10 psi is higher than 5psi. This means, the separation at higher pressure is more effective compared to low pressure.
Theoretically, in the operation of hydrocyclones, there are several parameters that influence the performance or efficiency of the hydrocyclone. These parameters can be divided into two parts which are; 1-‐ Operating parameters 2-‐ Geometrical parameters.
0
10
20
30
40
50
60
70
80
90
100
Y1 / %
0.10.1 0.5 1 5 10X / µm
5 psi • Feed • Overflow • Underflow 10 psi • Feed • Overflow • Underflow
Operating parameters a. Feed pulp density or viscosity b. Shape of particles c. Feed rate d. Pressure
Geometrical parameters a. Diameter of vortex finder b. Apex diameter c. Area of feed inlet d. The cone angle e. The cylinder diameter f. The cylinder length
Another factor that distribute to some error of hydrocyclone is due to the random
error while taking the reading will disturb the accuracy of the result. The mass of the sample is taken by using pulp density scale meter is not accurate as the horizontal horizon cannot be detected on the scale. Other than that, errors might have happen when calculating the time to fill up the flask stinging. Some errors can be avoided to acquire better result but some can be ignored and average reading will be taken. Besides that, error might also come from the uncovered rig. This cause the sample spilt from the rig where the overflow and underflow pulp are supposed to flow directly back to the rig as the circuit is closed circuit. CONCLUSION
From this experiment, it shows that hydrocyclone is efficient to operate at high pressure because the separation will be more effective. From the result, we can see that at 5 psi pressure, hydrocyclone can produce finer particle size distribution compared to 10 psi pressure. Therefore, the increase in pressure will also increase the efficiency of hydrocyclone. But this result might be different from the theory due to some errors that cannot be neglected while doing the experiment. In overall, the classification or separation of mineral particles in the hydrocyclone is due to: a. The nature of these particles such as size, shape and specific gravity. b. The physical properties of liquid such as density, percent solids and viscosity. c. The design parameters and operating parameters of the hydrocyclone itself. REFERENCE
§ B.A Wills, Mineral Processing Technology, 6th edition. An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery, England 1997.
§ Richard Holdich, Fundamentals of Particle Technology, Loughborough, United Kingdom, 2002.
§ Ph. Hasler, Th. Nussbaumer, Particle Size Distribution Of The Fly Ash From Biomass Combustion, Verenum Research, Langmauerstrasse 109, Ch -‐ 8006 Zurich, Switzerland, June 8–11 1998