In the asbestos ore screening and stratification stage, the factors affecting the stratification of the ore are two aspects, both the working parameters of the sieve and the nature of the ore. The working parameters of the sieve are mainly the rotational speed, amplitude and screen inclination.
Sieve speed: 250~270 rpm for flat rocking screen and 200 rpm for flat rotary screen; below this speed, the material on the screen is not easy to loose and stratified. Above this number of revolutions, the material jumps on the screen surface. Strong, but also not conducive to stratification.
Screen surface amplitude: plane shaking is 20-30 mm, plane rotation is 25-32 mm. If the amplitude is too small, the movement speed of the material on the sieve is too slow, which is not conducive to looseness. If it is too large, the asbestos fiber is easily lost through the ore layer.
Screen inclination angle: generally 5~7°, the inclination angle is too small, the material moves slowly on the screen surface, which is beneficial to material stratification, but the production capacity is reduced, the inclination angle is too large, and the material moves too fast on the screen surface, which will destroy Layering.
The ore properties affecting stratification are mainly ore particle size, humidity and feed amount.
The ore particle size is generally 30 mm. If the ore is too large, the ore is not fully dissociated, which is not conducive to sorting. If it is too small, the concentrate is seriously polluted by dust.
The ore humidity is preferably controlled to have a moisture content of less than 1%.
The feed amount is preferably kept at twice the maximum particle size of the material layer, and too thick and too thin is not conducive to stratification of the material.
The asbestos fiber phase affects the factors that absorb asbestos fibers, including two aspects, the structure of the suction nozzle and the velocity of the airflow.
The structural parameters of the suction nozzle are mainly its size and installation position.
The shape of the suction nozzle is generally rounded at the upper end and rectangular at the lower end, similar to the exhaust hood for removing smoke. The lower end area is usually 10-20% larger than the upper end area, and the side wall inclination angle is not less than 65-70%, so that the airflow speed in the suction nozzle is gradually increased to prevent the asbestos fibers that have been sucked out from re-sedimentation. In order to be able to absorb all the asbestos fibers on the sieve, the lower end of the suction nozzle is generally made into a narrow slit shape, and the slit length is exactly equal to the width of the sieve surface. The width of the slit is generally: for rough selection of 80 to 140 mm; for selection of 100 ~ 140 mm. In order to obtain a good cotton suction effect, a skirt plate is arranged on both sides of the slit so that the slit is flared, so that the airflow flows into the suction nozzle in a streamlined shape.
The suction nozzle is usually installed at the discharge end of the sieve. However, a roller can be added at the end of the sieve, and the suction nozzle is installed above the rotary projecting material of the drum. The advantage is that the rotation speed of the drum is faster, the material layer can be thinned, the suction efficiency of the asbestos fiber is increased, and the air volume is reduced.
The air flow rate is related to the height of the material layer from the lower end of the suction nozzle and inversely proportional to the height h 2 , which can be controlled by adjusting h. Generally h = 100 ~ 150 mm.
The main factors affecting the sedimentation effect of asbestos fiber in the stage of asbestos fiber are the structural factors of the cotton tube and the properties of the asbestos fiber.
The structural factors of the cotton-reducing cylinder include the diameter of the descending cotton, the inlet section and the degree of sealing of the feeder. The larger the diameter of the down tube, the lower the effect of the cotton drop. If the cotton reduction efficiency of Ñ„1500 mm is 1100%, increase to Ñ„2000 mm, it will be reduced to 99%, and then increased to Ñ„2500 mm, which is reduced to 97%. The size of the entrance section of the down tube affects the airflow speed. Usually the inlet wind speed is 18-20 m/s. Below this speed, the cotton reduction efficiency will be reduced. Above this speed, the efficiency of increasing cotton is not obvious. The degree of sealing of the cotton hopper is very important. The stricter the airtightness, the less air leakage, and the impact on the cotton reduction efficiency is small. Practice points out that when the hopper is leaking 5%, the cotton-reducing efficiency is 3 to 7% lower, and when the air leakage is 12 to 14%, the cotton cannot be lowered.
The factors in the properties of asbestos fibers are the feed concentration and the long-term variation of asbestos fibers. The test indicates that the feed concentration increases and the cotton reduction efficiency increases. If the concentration is less than 0.1%, the cotton-reducing effect is seriously deteriorated. The longer the asbestos fiber in the feed, the higher the radial movement speed of the asbestos is, and it is easy to settle down, so the cotton reduction efficiency is improved, and vice versa, the cotton reduction efficiency will be affected. The fiber is too short to settle at all.
Sieve speed: 250~270 rpm for flat rocking screen and 200 rpm for flat rotary screen; below this speed, the material on the screen is not easy to loose and stratified. Above this number of revolutions, the material jumps on the screen surface. Strong, but also not conducive to stratification.
Screen surface amplitude: plane shaking is 20-30 mm, plane rotation is 25-32 mm. If the amplitude is too small, the movement speed of the material on the sieve is too slow, which is not conducive to looseness. If it is too large, the asbestos fiber is easily lost through the ore layer.
Screen inclination angle: generally 5~7°, the inclination angle is too small, the material moves slowly on the screen surface, which is beneficial to material stratification, but the production capacity is reduced, the inclination angle is too large, and the material moves too fast on the screen surface, which will destroy Layering.
The ore properties affecting stratification are mainly ore particle size, humidity and feed amount.
The ore particle size is generally 30 mm. If the ore is too large, the ore is not fully dissociated, which is not conducive to sorting. If it is too small, the concentrate is seriously polluted by dust.
The ore humidity is preferably controlled to have a moisture content of less than 1%.
The feed amount is preferably kept at twice the maximum particle size of the material layer, and too thick and too thin is not conducive to stratification of the material.
The asbestos fiber phase affects the factors that absorb asbestos fibers, including two aspects, the structure of the suction nozzle and the velocity of the airflow.
The structural parameters of the suction nozzle are mainly its size and installation position.
The shape of the suction nozzle is generally rounded at the upper end and rectangular at the lower end, similar to the exhaust hood for removing smoke. The lower end area is usually 10-20% larger than the upper end area, and the side wall inclination angle is not less than 65-70%, so that the airflow speed in the suction nozzle is gradually increased to prevent the asbestos fibers that have been sucked out from re-sedimentation. In order to be able to absorb all the asbestos fibers on the sieve, the lower end of the suction nozzle is generally made into a narrow slit shape, and the slit length is exactly equal to the width of the sieve surface. The width of the slit is generally: for rough selection of 80 to 140 mm; for selection of 100 ~ 140 mm. In order to obtain a good cotton suction effect, a skirt plate is arranged on both sides of the slit so that the slit is flared, so that the airflow flows into the suction nozzle in a streamlined shape.
The suction nozzle is usually installed at the discharge end of the sieve. However, a roller can be added at the end of the sieve, and the suction nozzle is installed above the rotary projecting material of the drum. The advantage is that the rotation speed of the drum is faster, the material layer can be thinned, the suction efficiency of the asbestos fiber is increased, and the air volume is reduced.
The air flow rate is related to the height of the material layer from the lower end of the suction nozzle and inversely proportional to the height h 2 , which can be controlled by adjusting h. Generally h = 100 ~ 150 mm.
The main factors affecting the sedimentation effect of asbestos fiber in the stage of asbestos fiber are the structural factors of the cotton tube and the properties of the asbestos fiber.
The structural factors of the cotton-reducing cylinder include the diameter of the descending cotton, the inlet section and the degree of sealing of the feeder. The larger the diameter of the down tube, the lower the effect of the cotton drop. If the cotton reduction efficiency of Ñ„1500 mm is 1100%, increase to Ñ„2000 mm, it will be reduced to 99%, and then increased to Ñ„2500 mm, which is reduced to 97%. The size of the entrance section of the down tube affects the airflow speed. Usually the inlet wind speed is 18-20 m/s. Below this speed, the cotton reduction efficiency will be reduced. Above this speed, the efficiency of increasing cotton is not obvious. The degree of sealing of the cotton hopper is very important. The stricter the airtightness, the less air leakage, and the impact on the cotton reduction efficiency is small. Practice points out that when the hopper is leaking 5%, the cotton-reducing efficiency is 3 to 7% lower, and when the air leakage is 12 to 14%, the cotton cannot be lowered.
The factors in the properties of asbestos fibers are the feed concentration and the long-term variation of asbestos fibers. The test indicates that the feed concentration increases and the cotton reduction efficiency increases. If the concentration is less than 0.1%, the cotton-reducing effect is seriously deteriorated. The longer the asbestos fiber in the feed, the higher the radial movement speed of the asbestos is, and it is easy to settle down, so the cotton reduction efficiency is improved, and vice versa, the cotton reduction efficiency will be affected. The fiber is too short to settle at all.
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