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L·s- -1
Ï w - the density of water, t / m 3 ;
Sand pump selection and calculation
Sand pumps commonly used in ore plants include ordinary sand pumps and live slag pumps.
First, ordinary sand pump
(a) type
(1) PS-type sand pump, are horizontal centrifugal sand pump side into the slurry, with the temple conveying mineral pulp factories, heavy medium beneficiation of the working medium and the like, the maximum concentration of pulp is conveyed up to 60% to 70% (mass). The shaft seal is in the form of low-pressure packing. It needs to be cooled and lubricated with a small amount of water during operation. With the press-in configuration, the center line of the pump shaft is lower than 1m of the slurry surface;
(2) PH type sand pump is a horizontal single-stage single-suction cantilever type centrifugal ash pump, which can transport mixed liquid containing sand and gravel (maximum particle size not exceeding 25mm), and can allow sandstone with a small particle size of about 50mm to pass intermittently. . The shaft seal is sealed by a general packing, and the shaft seal water is injected at a working pressure higher than 98 kPa.
(3) PN sand pump is a horizontal single-stage single-suction cantilever centrifugal mud pump for conveying slurry. The maximum concentration (mass) is 50%~60%. The shaft seal is made of general packing, and the shaft seal water is injected at a working pressure higher than 98 kPa.
(4) PNJA and PNJFA type sand pumps are all horizontal single-stage single-suction heart-type rubber-lined pumps. The PNJFA model is designed to transport corrosive pulp. They can be used to transport a variety of pulp, but it is not advisable to transport a slurry containing sharp-angled solid particles. The maximum concentration of the transported slurry shall not exceed 65% (by weight), the temperature shall not exceed 60 °C, and the press-in configuration shall be adopted, and the water shall be sealed.
(5) PNL sand pump is a vertical single-stage centrifugal mud pump, which can be used to transport slurry in the concentrator. The maximum concentration (mass) is 50%~60%.
(6) PW-type pumps cantilevered horizontal single-stage centrifugal water pump, for conveying the liquid and below 80 ℃ with sewage or other suspension of the fibers, but not for conveying an acidic, basic and can cause metal Corrosive chemical mixture liquid. In order to prevent the sewage from leaking along the shaft, a water seal is required, and the pressure should be higher than the pump outlet pressure.
(7) PWF type pump is a horizontal single-stage single-suction cantilever centrifugal corrosion-resistant sewage pump, suitable for discharging acidic, alkaline or other corrosive sewage. The liquid temperature is within 80 °C; it needs to be sealed, and its clear water pressure is high. There are two kinds of seals at working pressure of 49~98 kPa (0.5~1.0kg/cm 2 ): mechanical seals (single end face) and general packing seals to prevent toxic and corrosive liquid leakage.
(8) Long-axis vertical centrifugal pump (commonly known as long-axis pump) is a special pump for transporting pulp, coal slurry and various flotation foams and medium-mineral products from the concentrator. It can also transport other liquids and sewage. It is a large-scale flotation. One of the indispensable supporting equipments in the production of the plant enables the flotation plant to realize flexible control of the circuit.
(9) Foam pump, which is a vertical centrifugal sand pump, has defoaming effect, and the defoaming rate is generally above 75%. It can be used for defoaming and conveying before concentration dehydration, reducing metal loss in concentrated overflow, and can be used for foam products. Delivery.
(2) Calculation of ordinary sand pump
The calculation of the sand pump should be based on the nature of the transported mortar (such as material size, density, hardness, slurry concentration, viscosity and corrosivity) to determine the type of sand pump, and then according to the amount of slurry delivered, head and pipe resistance loss, etc. The specific conditions of the sand pump are selected. Determine pipe diameter and transport slurry flow rate
A Determine the pipe diameter and the conveying slurry flow rate
Determining the appropriate slurry flow rate is an important part of the hydraulic pressure calculation of mortar pressure. There are many factors affecting the critical flow rate. It is difficult to find a calculation formula suitable for various sandstone properties, concentration, particle size and flow diameter. For long distances, the critical flow of high-concentration pipelines should be determined experimentally. The empirical value of the pressure is shown in Table 2.
The outlet diameter (critical pipe diameter) of the sand pump is calculated according to Equation 1.
According to DL, the standard pipe diameter D is selected. At this time, the actual flow rate of the slurry is Ï…=q Ï… /(0.785D 2 ), and Ï…>Ï… L is required .
Where q υ —— the amount of slurry transported, m 3 /s;
D L - critical diameter, m;
υ L ——minal pulp flow velocity, m/s; can refer to Table 1 and Table 2. [next]
Table 1 Summary empirical values ​​of critical flow rate of slurry in pressure pipe
Pulp concentration /%
When the ore density is ≤ 2.7t/m 3 , the critical flow velocity of various average particle diameters d w 1 / m·s -1
≤0.074
0.074~0.15
0.15~0.4
0.4~1.5
1.5~3.0
1~20
1.0
1.0~1.2
1.2~1.4
1.4~1.6
1.6~2.2
20~40
1.0~1.2
1.2~1.4
1.4~1.6
1.6~2.1
2.1~2.3
40~60
1.2~1.4
1.4~1.6
1.6~1.8
1.8~2.2
2.2~2.5
60~70
1.6
1.6~1.8
1.8~2.0
2.0~2.5
Table 2 Summary of minimum flow rate of slurry in pressure pipe
Ore size
Ore density / t · m 3
The amount of pulp /
Pulp concentration /%
15
20
30
40
50
Minimum flow rate / m·s -1
1.0
4.0~4.2
3.4~3.5
30~45
4.2
30~45
1.85
60~80
60~130
1.85
1.95
1.95
2.05
1.90
1.95
2.05
2.15
2.0
2.05
2.1
2.15
2.2
2.25
0.6~0
3.4~3.5
4.0~4.2
13~20
30~45
30~45
60~80
1.6
1.7
1.65
1.75
1.80
1.8
1.75
1.85
1.90
1.9
1.85
1.95
2.0
1.95
2.05
2.1
0.4~0
3.4~3.5
13~20
30~45
1.6
1.65
1.7
1.75
1.8
1.85
0.15
3.7~3.8
4.4~4.6
30~45
60~85
30~45
60~80
1.5
1.55
1.55
1.6
1.65
1.70
1.65
1.7
1.75
1.8
1.85
1.9
1.95
2.0
B Total calculation of the total lift required for sand pumping
Where H j is the total head required for the sand pump to send the slurry into water, m;
H——the required geometric height difference, m;
h——Remaining indenter, generally about 2m;
Ï p - pulp density, t / m 3 ;
L——including the straight pipe, elbow, gate, tee and other resistances converted into the total length of the straight pipe, m; check the table 3;
I——pipeline water resistance loss, can be selected according to the i value table, or can be calculated as follows
i=Aq 2 v (2a)
q v - slurry flow, m 3 /s;
A - specific resistance coefficient, check Table 4. [next]
Table 3 Various pipe fittings folding length
name
Pipe diameter / mm
50
63
76
100
125
150
200
250
elbow
Common connector
Fully open gate
Three links
Check valve
3.3
1.5
0.5
4.5
4.0
4.0
2.0
0.7
5.5
5.5
5.0
2.5
0.8
6.5
6.5
6.5
3.5
1.1
8.0
8.0
8.5
4.5
1.4
10.0
10.0
11.0
5.5
1.8
12.0
12.5
15.0
7.5
2.5
15.0
16.0
19.0
9.5
3.2
18.0
20.0
Table 4 Specific resistance coefficient A value
Inner diameter / mm
A
Inner diameter / mm
A
Inner diameter / mm
A
Inner diameter / mm
A
9
12.5
15.75
21.25
27
33.75
41
53
68
80.5
2255×105
3295×104
8809×103
1643×103
4367×102
93860
44530
11080
2893
1168
106
131
156
126
148
174
198
225
253
270
267.4
86.23
33.15
106.2
44.95
18.96
9.273
4.822
2.583
1.535
305
331
357
406
458
509
610
700
750
800
0.9392
0.6088
0.4078
0.2062
0.1098
0.06222
0.02384
0.01150
0.007975
0.005665
850
900
950
1000
1100
1200
1300
1400
0.00411
0.003034
0.002278
0.001736
0.001048
0.000605
0.0004322
0.0002918
NOTE: geometric sequence shown in the table index cast iron pipes, steel pipes index value of 75% in the table,
C sand pump converts the slurry from the slurry
Where H k - sand pump is converted into a clear water head by the lift slurry, m;
H s —— the clear water head detected by the sand pump performance curve, m;
K h —— the reduction rate of the lift affected by the slurry concentration, look up Table 5, can also be calculated as follows
K h =1-0.25C w (3a)
C w - pulp concentration (mass), %;
K m - the head reduction factor after impeller wear, generally 0.8~0.95;
Ï p , Ï w -- the meaning of the symbol is the same as before.
The result of the calculation must be such that the selected sand pump H k ≥ the required H j .
Table 5 Head drop rate K h value
Ρp/t·m -3
Kh-(1-0.25Cw)
Ï o =2.5
Ï o =2.6
Ï o =2.7
Ï o =2.8
1.05
1.10
1.15
1.20
1.25
1.30
0.98
0.96
0.95
0.93
0.92
0.90
0.98
0.96
0.95
0.93
0.92
0.91
0.98
0.96
0.95
0.93
0.92
0.91
0.98
0.96
0.95
0.94
0.92
0.91
Note: Ï o is the ore density, t/m 3 .[next]
D sand pump required power calculation
a Pump shaft power
Where P o - the shaft power of the pump, kW;
Η——the efficiency of the pump, check the water performance curve of the pump;
H s - the clear water head is found on the performance curve of the sand pump, m;
Ï p - pulp density, t / m 3 ;
q v —— the amount of slurry delivered by the sand pump, L/s;
b motor power
Where P is the required motor power, kW;
P o - the shaft power of the pump, kW;
η z —— transmission efficiency, belt drive η z =0.95; direct drive η z =1.0;
K——safety factor, when P o ≤40kW, K=1.20; when P o >40kW, K=1.10.
E sand pump performance adjustment
When the lift of the lift of the sand pump cannot meet the design requirements, it can be adjusted by changing the number of revolutions of the pump and the diameter of the discharge pipe, but the adjustment range cannot exceed the allowable range given on the product sample. The calculation formula is as follows:
a Pump's lift is proportional to its number of revolutions
Where q υ 2 —— the amount of pulp to be sent, L/s or m 3 /h;
q υ1 ——the amount of revolution when the number of revolutions of the pump is n1, L/s or m 3 /h;
n 1 - the operating speed of the performance curve, r / min;
n 2 ——When the pump lift is q υ2 , the required speed is adjusted, r/min.
b The lift of the pump is proportional to the square of its revolution
Where H 2 is the head when the number of pump revolutions is adjusted to n 2 , m;
H 1 - the lift of the number of revolutions of the pump at n 1 , m.
c pump power is proportional to the cube of its revolution
Where P 2 - the power of the pump when the number of revolutions is adjusted to n 2 , kW;
P 1 - the power when the number of revolutions of the pump is n 1 , kW.[next]
Second, Warman (WARMAN) slurry pump
The series, characteristics and versatility of the Woermann slurry pump currently in the production of the concentrator are as described in Table 6. The factors to be considered for the selection of such pumps are: slurry concentration, lift, lift, cavitation margin, efficiency. , number of revolutions, etc. The amount of lift and head are the basis for selecting specifications, series or not; the number of revolutions of the pump should not be too high. Generally, it is appropriate to take the right and left. In this case, the head can not be used in series, and the head should have a margin of 10% of its rated head; the material should be consulted with the manufacturer according to the need; the transmission method generally adopts elastic coupling and V-type V-belt drive, but V-type V-belt drive will increase the power consumption by 5%; to ensure that the effective cavitation margin is greater than the pump's necessary cavitation margin plus a cavitation safety margin of 0.3m, ie NPSH a = NPSH Y +0.3, can make the pump run without cavitation, otherwise the overcurrent parts of the pump will be damaged prematurely. Under severe cavitation, the pump will generate vibration and noise, and even lead to the lift of the pump. Quantity and efficiency have dropped dramatically. The effective cavitation margin refers to the energy of the vaporization pressure head of the unit weight liquid at the inlet of the pump.
Table 6 Warman slurry pump characteristics
Series pump type
Features and performance
Heavy
AH type
Heavy duty main series for conveying strong abrasion and high concentration grouting, can be used in multiple stages
AHP type
Multi-stage series use, strong abrasion, long-distance conveying slurry
M type
Strong abrasion, high concentration slurry
HH type
Low corrosion resistance, low concentration, single stage high lift slurry
H type
Higher efficiency than HH type, low concentration, good abrasion resistance, allowing large single-stage high lift for conveying particles
Light weight
L type
Low concentration (not exceeding 30% by weight), low abrasion grouting
Roll down slurry pump
SP type SPR type
Working centrifugal slurry under vertical immersion method, suitable for coarse particle high concentration slurry pump
Dredging gravel pump
D type G type
Horizontal, suitable for conveying coarse-grained mud and gravel slurry