GPS-900-3 high-frequency fine screen GPS-900-3 high-frequency fine screen was successfully developed in the early 1980s, and its structural properties are as follows.
1. Structure The high-frequency fine screen consists of exciter, slurry distributor, painter, screen frame, frame, product collection device, suspension spring and laminated screen (see the figure below).
The high-frequency fine screen is a multi-way ore screening device divided into three ways (upper, middle and lower), each of which can independently complete the screening process for feeding, screening and discharging. The screen surface is composed of three layers of screens of different pore sizes. The uppermost screen has the smallest mesh opening, which is called the main screen; the second screen has a larger size than the first screen, and the screen is called the anti-blocking screen; the third screen has a mesh aperture. As large as possible to increase the mesh area, but to maintain sufficient rigidity, strength, and can not be too thick due to the wire diameter, the first and second layer of mesh is uneven, reducing the service life. [next]
The exciter produces the exciting force required to grade the material. Its shape is long cylindrical, its length is equal to the width of the screen frame, and there are many heat sinks on the outer surface. Material good heat dissipation performance aluminum alloy. A three-phase AC excitation motor is installed in the middle of the long cylinder, and a pair of vibrators are arranged at both ends of the motor shaft. The vibrator composed of the weight block and the deviation block changes the angle between the deviation block and the weight block, and the magnitude of the excitation force can be changed to change the amplitude. When the weight block and the deviation block overlap, the excitation force is the largest, and the amplitude of the screen frame is also the largest; when the angle between the deviation block and the weight block is the largest, the excitation force is the smallest and the amplitude of the screen frame is the smallest.
The action of the vibrator is directly transmitted to the screen frame of the vibrating movement, and the screen frame is fixed on the bracket by four rubber springs by means of screws, so that the screen frame is suspended.
The high-frequency fine sieve is a three-way ore feeding, which realizes the uniformity of the amount of slurry, so that the amount of slurry, slurry concentration and particle size composition given to each screen surface are basically similar. The slurry distributor is a cyclone similar to a flat bottom without overflow pipe, tangentially feeding the ore and dividing into three tangential directions for discharge. In order to reduce the impact of the slurry on the screen surface, reduce the damage of the screen, and increase the service life of the screen, a porous rubber sheet of about 6 mm (adjustable) from the screen surface is installed at the ore end of the ore feeder. The slurry flowing from the slurry distributor is uniformly and slowly fed to the sieve surface through the sizing plate, the gas separation tank and the porous rubber sheet.
The screen surface of the high-frequency fine screen is made of stainless steel woven screen, and the rigidity and strength are reduced with the decrease of the sieve hole. Therefore, the bracket supporting the sieve surface of the fine-grain material should make the screen surface easy to be tensioned and laterally stressed. It is relatively uniform and does not produce unevenness, so as to improve the service life of the screen and the uniform distribution of the material. At the same time, the support strip of the bracket can not be too dense, so as to avoid reducing the effective area of ​​the screen surface and minimizing the quality of the vibration. A bracket with a certain degree of separation was used for comparison.
2. Main technical parameters and characteristics The main technical features of GPS-900-3 high frequency fine screen are as follows:
Vibration frequency, times / min 2850
Amplitude, mm 0.138～0.403
Slope, degree 26
Processing capacity, t / table · h separation of 0.15 ~ 0.3 materials, 4 ~ 12
Separate 0.10mm material, 4.0~6.0
Number of mine roads 3 Screen size (width / length), mm 3 × (900 × 700)
Effective area, m 2 1.64 mesh layer, layer 3
Screen material stainless steel vibration exciter power, kW 1.1
Its characteristics are as follows:
(1) The frequency is high and the amplitude is small. The conventional vibrating screen has a frequency of 1450 to 980 times/min and an amplitude of 1 mm, while the high frequency fine screen has a frequency of 1,850 times/min and an amplitude of between 0.13 and 0.4.
(2) High screening efficiency. Because the machine adopts high frequency, small amplitude, laminated screen and other structures and the mesh is not easy to block, the total screening efficiency of the machine is between 60% and 70%. [next]
(3) The excitation mechanism is simple and has a long service life. The excitation mechanism is composed of a motor and vibrator mounted in a long cylinder. It directly drives the screen frame to vibrate, thus improving the mechanical efficiency and saving energy. Each sieve requires only 1.1 kW of power. The vibrator is a one-piece piece, so it is easy to handle and replace. Production tests show that this type of shaker has a long service life of more than 3000h.
(4) Good vibration isolation performance.
(5) Laminated screen. The use of a laminated screen and the use of a large sieve to screen small materials is an important feature of high-frequency fine screening. The mesh aperture is larger than the classification granularity, and the secondary movement of the screen, the mesh hole is not easy to block, and at the same time, the wire diameter of the screen is correspondingly increased due to the increase of the mesh hole, thereby improving the service life of the screen.
(6) The effective area of ​​the screen surface is large. Since the screen surface is a woven screen, the effective area is large, about 45%. The effective area of ​​the sieve scorpion is below 25%, or even only about 10%.
(7) Three-way feeding. The high-frequency fine screen divides the ore into three ways at the same time, which is equivalent to increasing the width of the screen surface and reducing the thickness of the ore layer applied to the sieve surface, which is beneficial to the fine-grained material quickly contacting the screen surface and reducing the coarse particles. The transportation distance achieves both the improvement of processing capacity and the high overall screening efficiency.
(8) Low noise: high-frequency fine screen, due to the small amplitude, the screen frame is connected with the bracket through the rubber spring, and the rubber has good sound absorption performance and reasonable design of the vibration exciter structure, and the noise is small. The noise of the high-frequency fine screen was determined to be 82 to 84 dB.
(9) Work is stable. The high-frequency fine screen works in the super-resonance area, that is, the working frequency is much larger than the natural frequency of the system, and because of the use of the rubber spring, the vibration absorption and the vibration isolation performance are good. It will enter normal operation after about 4 to 6 seconds after starting; when it stops, it will stop after about 15 seconds. At the same time, during the normal operation, the change of the frequency caused by the change of the voltage and the change of the ore within a certain range have little effect on the amplitude, so the work of the machine is relatively stable.
3. Working principle The classification process of high-frequency fine screen is similar to that of ordinary mechanical vibrating screening equipment, but its classification principle is not exactly the same:
(1) Ordinary vibrating screen adopts single-layer sieve plate or sieve, the classification granularity is basically equal to the mesh size, and the high-frequency fine sieve adopts laminated screen. The mesh size of the three-layer sieve is larger than the separation granularity. The mesh size of the upper screen is greater than 0.6 times the separation size. Therefore, the relationship between the size of the sieved granular material and the size of the mesh is different from that of the ordinary shaker, and the ratio of the relative particle size is reduced.
(2) Due to the high frequency of the high-frequency fine screen, on the one hand, the surface tension of the slurry and the adhesion of the fine-grained material to the coarse particles are destroyed, and the attraction between the granular materials due to molecular attraction or electrostatic attraction is reduced. The adhesion between the particles increases the loose delamination and separation speed of the particles. On the other hand, due to the high-speed oscillation of the material on the sieve surface, the separation of the large density (specific gravity) useful minerals is accelerated, and the increase is increased. The probability of contact with the separated pore size material and the sieve pores is better, thereby causing better separation conditions, so that the material smaller than the separation particle size, especially the larger material and the slurry, passes through the sieve hole to become the sieve product. [next]
(3) Since the high-frequency fine screen adopts a laminated screen, although the three-layer screen is stretched together, the tension of each layer of the screen is not completely the same due to the error of the stretched net. Therefore, in addition to the movement of the screen together with the screen frame, there is relative movement between the screens, that is, because the tension of the screen pottery is different, there is a very small up and down flapping movement and lateral movement between the screens. . Due to this secondary movement, the grading of the material by particle size is accelerated, and the difficult-to-screen particles are relatively easily passed through the mesh to become the under-sieving product, or the extruded mesh is turned into a product on the sieve, so that the mesh is not easily clogged, and the mesh is increased. The area of ​​the effective mesh in the screening process.
(4) At present, in the industrial production, the vibrating screen used is divided into plane motion and vertical motion according to the motion form. In the plane motion, it is divided into circular motion, elliptical motion and linear motion. Since the vibrator of the high-frequency fine screen is installed above the screen frame, the screen frame is suspended, so the movement of the screen frame is not a single circular motion or elliptical motion. After testing, both circular motion and elliptical motion are tested. . In the middle road is a movement close to the circle, and the upper and lower roads are elliptical motion, and the long axis of the ellipse does not point in one direction, and their moving direction intersects above the screen frame, therefore, the upper, middle and lower three paths The trajectory of the screen surface is not the same. As shown below.
This movement of three different trajectories creates an ideal situation where the material is brought into close contact with the screen surface at the feed end and immediately becomes a thin layer along the screen when the material is applied to the screen. The surface is evenly distributed. At the same time, the material at the feed end is accelerated downward elliptical motion, and the material at the discharge end is decelerated (the elliptical motion of the mountain upwards), thereby achieving the ideal velocity distribution required for the screening material.
4. In the iron ore processing plant in Beijing Miyun iron ore processing plant applications use this equipment. The ore processed by the plant belongs to the Anshan-type sedimentary metamorphic iron deposit. The ore is dense block, hemp-like and thick strip-like structure with a gradual relationship; the metal mineral is magnetite, a small amount of hematite and yellow ore. . The gangue minerals are mainly quartz , followed by feldspar , hornblende, chlorite, biotite, etc.; the ore is granular structure, due to early metamorphism, coarse particles, magnetite granularity is generally 0.4mm, the maximum is 4mm, red The iron ore has a fine particle size and is generally below 74 μm. The ore crystal grain size of each ore body varies greatly, which makes it difficult to optimize the size of the fine mesh. [next]
The high-frequency fine screen and the curved screen of the installation part of the figure below were compared. The production operation showed that: (1) the high-frequency vibrating fine screen screening efficiency was 80-90%, and the classification efficiency was 75-80%. It is 35 to 45% higher than the curved screen and 35 to 40% higher. Due to the low classification efficiency of the curved sieve, the useful minerals are over-grinded, which affects the yield and other mineral processing indexes; (2) the high-frequency vibrating fine sieve has a yield of 74.35%, which is 34.82% higher than the curved sieve; (3) due to the high frequency The vibration stratification of the vibrating fine screen has a significant ratio, and the material with high grade is obviously enriched under the sieve, and the grade under the sieve is 12.59% higher than the average grade on the sieve. The grade under the curved sieve is 9.4% higher than the grade on the sieve.
This type of screen has been promoted and applied in China more than 70 units. The stainless steel screen (1Cr 18Ni 9Ti) has a service life of more than 1000h.
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