High frequency fine screen
(1) High-frequency fine screen
Northeast University of Technology in 1982 and developed a GPS-800 × 1680 high-frequency fine sieve, and completed extensive testing in the industrial Waitoushan dressing. The machine is characterized by linear motion, using mechanical parts and lubrication methods such as domestic general-purpose motors, bearings, sieve plates.
A structure The structure of high-frequency fine screen (Fig. 1) is mainly composed of screen frame, sieve surface, counterweight wheel, sieve discharge outlet, sieve discharge outlet, rubber spring, frame, motor and so on.
The screen frame is welded by steel plates and steel pipes, and welded with ribs. The sieve surface is composed of 28 nylon sieve plates with a sieve hole of 0.15mm. The sieve surface is fixed on the screen frame by square wood chips and wedges, which is convenient to replace. The sieve surface is divided into two ways to feed the ore, and the discharge end of the sieve is provided with first and second screen upper discharge outlets and a lower sieve discharge outlet. The function of the counterweight wheel is to generate an exciting force to make the sieve vibrate in a straight line; the magnitude of the excitation force and amplitude can be adjusted by adjusting the number of counterweights. The rubber spring can reduce the dynamic load on the foundation when the sieve is working. The entire screen frame is connected to the frame by a rubber spring, and the front and rear frames can be adjusted to the upper and lower positions to change the inclination angle of the screen surface. The two motors are mounted on two bases.
B Working principle
The high-frequency fine-screen linear vibration is realized by the principle of two unbalanced heavy motions, as shown in Figure 2. The two motors respectively drive the upper and lower shafts to rotate in opposite directions. The synchronous relative rotation is superimposed on the excitation force of the screen surface at an angle of 30°, and the excitation forces in the other directions cancel each other to form a single excitation force along the vibration direction, so that the sieve is reciprocated by a linear trajectory. . Since the sieve only vibrates in the direction in which the exciting force is superimposed, there is no vibration in other directions, and the sieve works very smoothly.
The machine has high vibration and small amplitude, and the material is vibrated at high speed on the sieve surface, which is easy to loosely stratify. The material smaller than the sieve hole and the water pass through the sieve hole, and the screening efficiency is high, which is suitable for screening the granule material, Grading. [next]
C Technical performance The technical performance of GPS-800×1680 high frequency fine screen is as follows:
Effective screen area 1.2m 2
Screen size 0.15mm
Screen angle 15°～25°
Full amplitude 0.6~2.2mm
Vibration time 2860/min
Motor power 2 × 2.2kW
Total weight 925kg
Dimensions 2.7 × 1.4 × 3.2m
D Industrial test The industrial test of the machine was carried out in a series of Shantoushan concentrator. Parallel to the on-site vibrating fine screen, the magnetic separation coarse concentrate product was processed, and its screening efficiency and processing capacity were examined. 360h.
The test flow is shown in Figure 3.
The bearing life is evaluated by continuous operation of 3100h, and it is dry oil lubrication, which can run continuously for half a year.
Three kinds of sieve plates have been selected for the sieve plate test: (1) stainless steel sieve plate, the minimum mesh size is 0.2mm, and the price is expensive; (2) stainless steel braided mesh screen, the mesh hole is 0.1mm, the strength is low, it is not wear-resistant, and it is easy to break. , short life; (3) nylon sieve plate, mesh hole is 0.15mm, with elasticity, strong wear resistance, not easy to block, long life, can be used for more than 4 months, and the price is cheap, the disadvantage is that the effective area is low, still to be produced Sieve plate having a mesh size of less than 0.15 mm.
It can be seen that the mass efficiency and mass efficiency of the high-frequency fine sieve are higher than that of the shock-absorbing fine sieve, and the treatment amount per unit area is high, and the iron grade on the sieve is 3-4% lower, but the iron grade under the sieve is also 2%, which is slightly larger than the sieve hole. Equipment structure related. GPS-800×1680 high-frequency fine screen when the concentration of ore is 55~65%, when the treatment volume is 15t/(h · m 2 ), the screening efficiency is: 73～82%.[next ]
(II) GPS-900-3 high-frequency fine screen Changsha Research Institute of Mining and Metallurgy developed GPS-900-3 high-frequency fine screen in 1981, and carried out research on screen material. The machine adopts high vibration times, small amplitude, laminated anti-blocking screen, rubber spring floating support, and three-way feeding device. The operation is stable and reliable, and the screening efficiency is 60-70%. The YK-Z-900 vibrator is used to laminate the anti-blocking screen, and the service life is one month, which can better prevent the screen from being blocked.
A structure The machine is mainly composed of vibrator, sieve frame, feeding system, mining funnel and frame (Figure 4).
A vibrator having a cylindrical aluminum alloy housing, built with a three-phase asynchronous motors, bearings, and above the two pairs of emphasis block portion fixed to the vibrator sieve box. The screen frame is supported by the four rubber springs on the frame in a floating manner and forms a certain inclination angle with the horizontal plane. The screen frame is divided into upper, middle and lower three roads to form three independent screen surfaces, each of which completes the screening operation. Each screen surface consists of a three-layer stainless steel screen, and the ore supply system includes a slurry distributor and a feeder, which are respectively placed above the frame.
The device has the following characteristics in terms of structural performance:
(1) High frequency vibration. This vibration mode can destroy the surface tension of the slurry, reduce the viscosity of the slurry, loose the material layer, increase the ability of the fine material to penetrate the screen, reduce the blockage of the screen, and improve the processing capacity of the fine screen. The vibrator bearing is dry and slippery.
(2) Laminated screen. The upper two layers are the main screen, and the pore size is slightly larger than the dry separation particle size, and the sieve is used. This replacement of a screen with a smaller aperture by a screen with two larger apertures makes it possible to make the screen have a relatively coarser wire diameter and thus extend the life. The lower layer is the support net and serves as a support. There is slight relative vibration between the three layers of screen, which can effectively prevent the clogging of the screen.
(3) Three-way feeding. It can improve the processing capacity of the equipment, because under the high frequency vibration, the material grading process can be completed in a shorter time and a shorter distance, so a shorter screen length can be used.
(4) Reasonable feeding method. Through the feeder and the porous rubber sheet, the slurry fed into the screen is evenly distributed, and the impact of the slurry on the screen surface is alleviated, thereby improving the screening efficiency and reducing the wear of the screen surface.
The slurry is evenly fed into the screen through the slurry distributor and the feeder. Due to the high-frequency vibration, the fine-grained material smaller than the separation particle size quickly passes through the screen, and the fine particles partially mixed in the product on the sieve are loosened and sieved off due to the water spray on the sieve surface, becoming the undersize product. . The coarse particles and the small amount of fine particles larger than the separation particle size, because of the vibration of the sieve frame and the slope of the sieve surface, continuously move downward on the sieve surface to become a product on the sieve. [next]
This is a circular motion high-frequency fine screen with a projectile strength designed to
Where A———the amplitude of the screen frame;
ω———the angular velocity of the shaft that drives the movement of the screen frame;
a———the angle of the screen surface;
g———Gravity acceleration.
Here are the main technical features:
Vibration frequency 2850 times / min
Amplitude 0.2~0.35min
Number of mine roads 3 roads Screen size (length × width) 700 × 900mm
Effective screening area 1.6m 2
Screen angle (upper, middle and lower) 25°, 26°, 27°
Vibrator motor power 1.1kW
Feeding concentration 25~40%
Separation particle size 0.1～0.4mm
Processing capacity Separation particle size 0.1mm 4～6t/h
Separation particle size 0.15mm 6～8t/h
Unit area treatment volume separation particle size 0.1mm 2.5~4t/(m 2 · h)
Separation particle size 0.15mm 4~6t/(m 2 · h)
Dimensions 2700 × 1.400 × 3200mm
B Non-magnetic stainless steel fine mesh In recent years, research on Cr-Mn-Ni-N stainless steel has made great progress, and a large number of patented alloys have appeared. Basic performance data for some representative nitrogen-fortified austenitic stainless steels.
18-2Mn has a high overall performance, and its similar grades are Carpenter 18Cr-2Ni-12Mn, Crolog-299, Nitronic-32 and so on. Another feature of this alloy is that it does not produce martensite transformation (i.e., no magnetic transition) under a large number of cold deformation conditions.
The raw materials are smelted in an induction furnace, cast into ingots, and then forged, rolled, and drawn into filaments of Ñ„ 0.1 mm. After annealing, it is woven into a 100-mesh square-hole screen.
The indicators achieved by the test are as follows:
Mechanical properties: σ b =850MPa δ=60%
Ψ=48% HRb=95
Wear resistance: weight loss is 0.0399g (under the same test conditions, the weight loss of 1Cr18Ni9Ti sample is 0.0515g)
Corrosion resistance: Good corrosion resistance in 2% H 2 SO 4 and 2% HNO 3 aqueous solutions.
Metallographic organization: single phase, non-magnetic.
Among the factors affecting the life of the screen, in addition to the hardness of the material, the tensile strength of the material is also an important factor.
The development of this nitrogen-containing high-strength, wear-resistant, non-magnetic stainless steel screen has a longer service life than the current domestic 1Cr18Ni9Ti stainless steel screen, and is a better fine mesh material.
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