There are many types of screening machines. The commonly used screening machines in iron ore plants include fixed bar screens, various vibrating screens, and wet fine screens.
1. Fixed Rod Screen
The fixed rod screen includes a grid screen and bar screen, which can be installed horizontally on the top of the coarse crusher silo to prevent large pieces from entering the crusher. It can also be installed obliquely in front of the crusher for pre-screening. Its structure is simple, usually welded with steel rods, channel steel, steel rails, and other materials.
The mesh size of the strip sieve is about 1.1 to 1.2 times the undersize product. Generally, the mesh size is not less than 50mm. The width of the bar screen depends on the width of the feeder, conveyor, and crusher, and should be more than 2.5 times the largest block in the feeder. The length L of the bar screen should be selected according to the width B, generally 2 times the width.
2. Vibrating Screen
A vibrating screen is a kind of screening machine commonly used in concentrators. According to the different trajectories of the screen frame, it can be divided into circular motion vibrating screen and linear motion vibrating screen. In iron ore dressing plants, circular motion vibrating screens are mainly used, including single-axis inertial vibrating screens, self-centering vibrating screens, and heavy-duty vibrating screens.
2.1 Inertial Vibrating Screen
The screen box and the screen are supported on the frame by means of springs. The two sections of the main shaft are equipped with two eccentric weight wheels near the bearing, and there are counterweights on the wheels. When the belt pulley drives the eccentric weight wheel to rotate through the main shaft, a relatively large inertial centrifugal force will be generated, which will act on the spring and the screen box, thereby causing the screen to vibrate. Adjusting the position of the weight on the eccentric weight wheel is different, and different inertial forces can be obtained to adjust the amplitude of the sieve. The material on the screen is forced to vibrate up and down in the vertical direction due to the vibration of the screen, which causes the material to be loose and stratified. At the same time, the screen holes are not easily blocked, thereby achieving the purpose of screening.
2.2 Self-centering Inertial Vibrating Screen
Self-centering inertial vibrating screens are generally suspended on supports, also known as universal hanging screens. The screen frame is mounted on the bearing of the eccentric part of the eccentric shaft. The screen frame is hung on the fixed structure by springs. The flywheel is equipped with a counterweight. The centrifugal force generated by the counterweight when the flywheel rotates is balanced with the centrifugal force generated by the screen frame when it rotates. At this time, the screen frame moves in a circle around the main shaft, and the centerline of the main shaft remains unchanged in space. This type of transmission screen is called a self-centering inertial vibrating screen.
2.3 Heavy-duty Vibrating Screen
The principle of the heavy-duty vibrating screen is similar to the self-centering vibrating screen, but the main shaft of the vibrator is not eccentric at all, and the automatic adjuster in the pulley is used to achieve the purpose of self-centering during operation.
3. Wet Fine Screen
The wet high-frequency vibrating fine screen is mainly used as an iron ore concentrate regrind and classification equipment in iron ore concentrators, or as a fine grinding and classification equipment. The main advantage is that the classification particle size is controlled according to the geometric size, which avoids the problem of anti-enrichment of iron minerals in the low flow during the cyclone classification process. At present, the fine screens commonly used in concentrators mainly include Derek’s high-frequency fine screens and domestic MVS high-frequency fine screens.
Gongyi Forui Machinery Factory is a high-quality enterprise specializing in the production of beneficiation equipment. Over the years, it has produced gravity beneficiation, magnetic separation, flotation, and other beneficiation equipment, and has accumulated a lot of practical experience. Forui Machinery is involved in lead-zinc ore, gold ore, fluorite, barite, pyrite, hematite, limonite, magnetite, manganese ore, antimony ore, tungsten ore, tin ore, celestite, etc. In the field of beneficiation of a variety of minerals, fruitful results have been achieved.
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