First, the choice of hydrocyclone
Hydrocyclones are widely used in grading, de-sludge, dewatering and other operations. The main advantage is that the structure is simple, there is no moving parts, and the occupied area is small; in the case of finer granularity, the classification efficiency is higher than that of the spiral classifier. The main disadvantage is that the mine needs to be pumped and pumped, and the power consumption is high; the operation is more complicated than the spiral classifier. The suitable size range of the hydrocyclone is generally 0.3~0.01mm.
The specifications of the hydrocyclone depend on the amount of ore and overflow particle size that needs to be treated. When the amount of ore to be treated is large and the overflow particle size is coarse, a large-scale hydrocyclone is selected; otherwise, a small-sized hydrocyclone should be used. When the treatment of large amount of minerals requires fine flow size, a small-scale hydrocyclone group can be used.
The structural parameters and operating parameters of the cyclone have a great influence on the overflow particle size and classification effect, and should be carefully considered when selecting. The relationship between the main structural parameters of the cyclone and the diameter D of the cyclone, the general range; the equivalent diameter of the feed port d f = (0.15 ~ 0.25) D; the diameter of the overflow pipe d o = (0.2 ~ 0.4) D; grit The mouth diameter d u = (0.06 ~ 0.20) D; the cone angle a ≤ 20 °.
The inlet pressure is one of the main parameters of the hydrocyclone, usually 49~157kPa (0.5kgf/cm 2 ~1.6kgf/cm 2 ). The general relationship between inlet pressure and overflow particle size is shown in Table 1.
Table 1 General relationship table of inlet pressure overflow granularity
Overflow particle size d 95 /min | 0.59 | 0.42 | 0.30 | 0.21 | 0.15 | 0.10 | 0.074 | 0.037 | 0.019 | 0.010 |
Import pressure / kPa (kgf / cm 2 ) | 29.4 0.3 | 49 0.5 | 39~78 (0.4~0.8) | 49~98 (0.5~1.0) | 59~118 (0.6~1.2) | 78~137 (0.8~1.4) | 98~147 (1.0~1.5) | 118~167 (1.2~1.7) | 147~196 (1.5~2.0) | 196~245 (2.0~2.5) |
Second, the hydrocyclone calculation
The calculation of the hydrocyclone uses the following two methods.
A The main steps and calculation formulas of the original Soviet Povarov calculation method are as follows:
(1) Select the diameter of the spinner and calculate the volumetric processing capacity of the cyclone and the number of units required.
Volume processing amount is calculated by the following formula
Where q V - the amount of treatment by ore volume, m 3 /h;
K a —— hydraulic cyclone cone angle correction factor;
When a = 10 °, K a + 1.15; when a = 20 °, K a = 1.0;
K D - hydrocyclone diameter correction factor;
d f —— the equivalent diameter of the mine mouth, cm
b, h - respectively, the width and height of the ore mouth, cm;
p o ——the working pressure of the cyclone to the mine mouth, MPa;
d o ——overflow pipe diameter, cm;
D——the diameter of the cyclone cylinder, cm.
(2) Determine the diameter of the grit chamber according to the range given by the sample body, and check the unit cross-sectional area load (in terms of solid volume) so as to be in the range of 0.5~2.5t/(cm 2 ·h).
(3) Calculate the ore pressure required for the cyclone.
(4) Calculate the upper limit of the overflow particle size d 95 so that it meets the requirements of the overflow particle size. See Table 2 for the relationship between the different fractions of the cyclone feed and overflow.
Where d 95 - the upper limit of the overflow particle size, μm;
C f - the weight concentration of the ore, %;
d u —— sanding mouth diameter, cm;
Ρ——the density of solid materials in the pulp, t/m3;
D, d o , p o , K D , - the same formula (1). [next]
Table 2 Relationship between different fractions of the cyclone feed and overflow
Size/μm | content/% | |||||||||
-74 | 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 95 |
-40 | 5.6 | 11.3 | 17.3 | twenty four | 31.5 | 39.5 | 48 | 58 | 71.5 | 80.5 |
-20 | 13 | 17 | twenty three | 26 | 35 | 46 | 55 | |||
Upper limit granularity, d 95 | 430 | 320 | 240 | 180 | 140 | 94 | 74 | |||
B Krebs calculation method
(1) Separated particle size d 50 , corrected separation particle size d 50 (c) Calculated Separation particle size d 50 means a very narrow level of particle size at a recovery rate (distribution rate) of 50% in grit and overflow. In the actual classification efficiency curve of the cyclone (curve 1 in Figure 1), the particle size corresponding to the particle fraction recovery rate of 50% in the grit is the separation particle size d50.
In the cyclone grading process, the material entering the grit comprises two parts: a part of the material entrained by the water into the grit, the part of the material is not actually classified, and the relative amount of water in the grit is the water in the grit. The ratio (decimal) is equivalent; the other part is the material that has been graded into the grit. Therefore, when calculating the grit level recovery of the cyclone, the unclassified material entrained by the water should be deducted, namely:
Where y c and y are respectively the corrected recovery rate and the actual recovery rate of a certain level in the grit, respectively;
R f - The ratio of water in the grit to the water in the ore, in decimals.
The classification efficiency curve (curve 2 in Fig. 1) made by y c instead of y is called a corrected classification efficiency curve or a corrected recovery rate curve. The separation particle size on this curve is referred to as the corrected separation particle size expressed as d 50 (c) .
In the grinding circuit, the overflow particle size of the cyclone is generally expressed as a percentage of a specific particle size d r , and its relationship with d 50 (c) is shown in Table 3. If the percentage of a particular particle size in the overflow is known, the corrected separation particle size d 50(c) can be calculated according to the data in Table 3 .
Table 3 Relationship between hydrocyclone overflow particle size d50(c)
a specific particle size (d r ) percentage in the overflow /% | 98.8 | 95.0 | 90.0 | 80.0 | 70.0 | 60.0 | 50.0 |
d 50(c) /dr | 0.54 | 0.73 | 0.91 | 1.25 | 1.67 | 2.08 | 2.78 |
(2) Calculate the diameter of the hydrodynamics D as follows:
D=0.0234d 50(c) 1.515 P o 0.424 (Ï-1) 0.758 ×(1-0.0189cÏ…) 2.167 (41)
Where D - the inner diameter of the cyclone, cm;
d 50(c) - correct separation particle size, μm;
P o - cyclone feed pressure, kPa;
Ρ——material density, t/m 3 ;
Cυ——the concentration of the ore concentration, %. [next]
(3) Calculate the number of cyclones according to the processing capacity of the standard hydrocyclone (see Figure 2). It should be noted that the treatment shown in Figure 2 is based on water, and the slurry is slightly higher than this data. Therefore, according to this calculation, the number of cyclones is partial to insurance, which is allowed in engineering design.
(4) According to the relationship between the flow rate of the grit chamber and the diameter of the grit chamber, the diameter of the grit port is determined by Figure 3.
[next] C hydrocyclone calculation example
A certain grinding circuit, the hydrocyclone grading and the ball mill constitute a closed circuit, the new ore supply of the circuit is 250t/h, the cyclone overflow is 40%, and the overflow particle size is -74μm, accounting for 60%, ore density. At 2.9 t/m 3 , the cyclone inlet pressure is 55 kPa and the grinding circuit has a cyclic load of 225%. The material balance results calculated according to the above conditions are shown in Table 4. Try to calculate the specifications and number of hydrocyclones.
Table 4 Hydraulic cyclone material balance calculation results
project | unit | overflow | Sanding | Feed mine |
Solid amount | t/h | 250 | 562 | 812 |
Water volume | m 3 /h | 375 | 187 | 562 |
Amount of pulp | t/h | 625 | 749 | 1374 |
Weight concentration | % | 40 | 75 | 59.1 |
Volume concentration | % | 50 | 33.2 | |
Pulp density | t/m 3 | 1.355 | 1.966 | 1.632 |
Pulp volume | m 3 /h L/s | 461 128 | 381 106 | 842 234 |
There are two ways to calculate
(1) Povarov calculation
According to the equipment sample, a hydrocyclone with D=50cm and cone angle a=20° can be selected. The size of the feeding port is 11cm×12cm (diameter d f =13cm), and the diameter of the overflow pipe is d o =18cm. Diameter d u =9cm.
Processing volume calculation:
According to the calculation results, 6 D=50cm cyclones are selected, and 3 other spares are used.
The diameter of the grit chamber is d u =9cm, and the cross-sectional area is 63.6cm 2 . The solid load per unit section of the grit chamber is , within the allowable range.
, within the allowable range. Calculate the actual required ore pressure:
Referring to Table 2, this upper limit particle size satisfies the requirement of -74 μm accounting for 60%.
(2) Krebs method calculation
According to the requirement of overflow particle size -74μm60%, look up Table 3 and calculate the corrected separation particle size:
d 50(c) =2.08×74=154(μm)
Calculate the diameter of the cyclone:
D=0.0234 d50(c) 1.515 P o 0.424(Ï-1) 0.758 (1-0.0189cÏ…) 2.167
=0.0234×154 1.515 ×550.424(2.9-1) 0.758 (1-0.0189×33.2) 2.167
=50.6 (cm)
A D=51cm Krebs standard cyclone is available.
As shown in Fig. 2, when the mine pressure is 55 kPa, the D=51 cm cyclone treatment capacity is 44 L/s, then the number of cyclones For the station, 6 units can be used, and 3 units can be reserved.
For the station, 6 units can be used, and 3 units can be reserved. Select the size of the grit port according to the volume flow of the grit slurry: the volume flow of the grit slurry of each cyclone is According to Figure 3, the diameter of the grit is 9.5cm.
According to Figure 3, the diameter of the grit is 9.5cm. 1 Ton Mini Excavator,Hydraulic Mini Excavator,Rc Hydraulic Excavator,Farm Mini Excavator
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