Incorrect installation of the overflow pipe of the hydrocycl
Writer： admin Time：2020-08-03 11:29 Browse：℃
The overflow pipe is used to send the overflow of the hydrocyclone to the next feat. The pipe can be regarded as the extension of the cyclone device. When it is installed incorrectly, it will have a negative impact on its working indicators. First, the slurry passes through When the duct flows through, there will be fluid resistance. Secondly, the duct becomes a siphon. Normally, the overflow does not fill the entire section of the duct, so air may be sucked into the air column area of the hydrocyclone through the duct. At the same time, the duct will work periodically, and its section will be filled from time to time and sometimes underfilled. This pulsating working state has a bad influence on the classification index, so the diameter of the cyclone duct should be larger than the overflow pipe. Please pay special attention when installing.
Hydrocyclones are mainly used in ore dressing: ① Dense medium cyclones are common heavy medium separation equipment. ②As a classification equipment in the grinding circuit, especially as a classification equipment for fine grinding. ③ Desliming and thickening the pulp.
The main consideration for selecting the appropriate size and design structure of the cyclone is the classification target rather than the relationship between its capacity, inlet aperture, vortex detector diameter and tip diameter.
It is rarely necessary to change the size of these apertures, unless the classification target or the working conditions of the equipment change. For the operation of the cyclone, there are many factors that affect it. The following briefly discusses some factors that affect the operation of the cyclone:
1, dilute the feed
Dilution of the feed is an effective control method. Increased dilution water will achieve faster and better separation. The amount of dilution water can also be adjusted to maintain a constant water level in the water tank. Although the operator must be aware of the possible changes in the separation, when the dilution of the feed is high, the change in the separation situation will be small.
2, pressure control
The pressure drop on the cyclone is the difference between the pressure at the inlet of the cyclone and the overflow pressure. When the cyclone is discharged into the atmosphere, the pressure at the inlet of the cyclone is the pressure drop, and the pressure drop forces a certain volume of fluid An indicator of the energy required to pass through the cyclone is not an indicator of the pressure model or flow rate under study. Excessive pressure will increase the operation and maintenance costs of the pump, so it should be avoided. The higher the pressure drop, the greater the flow through the cyclone, and the higher the pressure drop will also produce a better separation effect.
3, cyclone orifice plate
The various small holes on the cyclone also have a great impact on its performance, and the replacement of these holes requires the system to shut down.
The overflow pipe is used to send the overflow of the hydrocyclone to the next feat. The pipe can be regarded as the extension of the cyclone device. When it is installed incorrectly, it will have a bad influence on its working indicators. The slurry passes through the pipe. When it flows through, there will be fluid resistance. Secondly, the duct will become a siphon. Normally, the overflow does not fill the entire section of the duct. Therefore, air may be sucked into the air column area of ??the hydrocyclone through the duct. It will also form a state of periodic work of the catheter, and its section will be filled from time to time, and sometimes not filled. This pulsating working state has a bad influence on the classification index, so the diameter of the cyclone duct should be larger than that of the overflow pipe. Please pay special attention to the diameter when installing.
Operation and maintenance of hydrocyclones
1. Stable pressure to mine.
The feed ore of the cyclone must have a certain pressure. Maintaining the stability of the feed pressure is the key to ensuring the high efficiency of the cyclone.
In production and life, the ore feeding method of the cyclone can adopt the ore feeding method of the pressure stabilization box, that is, the height difference is used to feed the ore into the cyclone by the pipe or the sand pump is used to send the slurry to the higher pressure stabilization box. The flow device stabilizes the pressure. Due to the fluctuation of the slurry volume, the liquid level of the slurry pool of the static pressure to the mine fluctuates, resulting in the pressure of the cyclone to the mine is not stable enough, resulting in the pressure change of the cyclone and the fluctuation of the classification efficiency.
In actual operation, due to the wear of the sand pump impeller, the pressure of the cyclone to the mine drops and the amount of slurry decreases. At this time, the number of cyclones should be adjusted according to the changes in the amount of slurry and pressure.
2. Strengthen product quality inspection.
The main purpose is to check that the concentration and particle size of the sedimentation and overflow meet the production requirements. If the overflow concentration suddenly increases, it should be observed whether the amount of slurry entering the flotation machine decreases. If the amount of slurry does not decrease and the sedimentation is normal, If it is the cyclone used for the second stage classification, it indicates that the grinding capacity of the first stage has increased too much and should be overhauled in time.
If the overflow concentration suddenly becomes small, check the cyclone sedimentation situation immediately. If the cyclone sedimentation is sparse, it means that the amount of ore is insufficient, or the sand pump pressure is insufficient, and it should be repaired immediately.
If the overflow flow suddenly increases, the water supply should be closed immediately, and the ore supply should be stopped to restore it to normal. The cause of the clogging of the cyclone is mostly due to the excessive processing capacity or the excessively high concentration of the ore. There are debris in the ore slurry and block the sand spout.
3. Separate slag seriously.
If the slag isolation work is not done well and the grit port is blocked, a slag isolation screen must be installed in front of the slurry tank or the pump, and the debris on the screen should be removed in time.
The hydrocyclone is used in the swirling dezincification of blast furnace sludge. The sludge in Dalian produced in the ironmaking process contains a large amount of iron and carbon. It is a good raw material for ironmaking. The zinc content exceeds the standard, so the sludge must be dezincified before it can be recycled as ironmaking raw materials. The zinc in the blast furnace sludge is mainly in small particles of sludge, so the sludge can be removed by a hydrocyclone. The zinc element in the sludge is separated from the small particles, so that the zinc content of the sludge reaches the standard and can be recycled.
The investigators conducted an experimental study on the cyclone separation of blast furnace sludge, analyzed the performance of the hydrocyclone in particle separation and classification by numerical calculation methods, and obtained the particle classification in the hydrocyclone through experiment and numerical methods. The efficiency curves of the two are quite consistent. However, the numerical simulation results of all these studies are obtained under the condition that the particle inlet volume concentration is very low. Due to the strong swirling effect in the cyclone, the cyclone The concentration in a local area is much higher than the inlet concentration, which leads to the difficulty of numerical simulation. At present, we cannot perform numerical simulation on the solid-liquid multiphase flow in the cyclone under the condition of higher inlet particle concentration. Therefore, Compared with the experiment, the particle inlet concentration used is quite different. However, scholars have been thinking about why the numerical simulation results for the low inlet concentration situation can be consistent with the experimental results obtained under the high inlet concentration situation, and finally concluded that the particle inlet concentration does not significantly affect the hydrocyclone Classification of particles in the vessel.
After the hydrocyclone is installed successfully, it needs to run for about 5-10 minutes under load. The purpose of this is to flush out the debris inside the cyclone. If there is a dripping place, tighten the bolts. At this time, we have to observe the working pressure of the slurry tank and the system. When both of them remain stable, the cyclone reaches normal operation.
Through the above steps, we can ensure that the hydrocyclone starts to operate. There are two points that need special attention during operation:
1. The working pressure must be continuously stable within the required range, and the concentration of feed, overflow and underflow must be within the required range;
2. From the concentration and particle size composition of the feed, overflow and underflow, the material balance calculation table and the classification efficiency of the cyclone can be calculated.
Working principle of hydrocyclone
The hydrocyclone consists of a hollow cylinder in the upper part and an inverted cone communicating with the cylinder in the lower part. The two constitute the working cylinder of the hydrocyclone. In addition, the hydrocyclone has a feed pipe, an overflow pipe, an overflow pipe and a grit port.
The hydrocyclone uses a sand pump (or height difference) to spin the pulp into the cylinder along the tangential direction at a certain pressure (usually 0.5 to 2.5 kg/cm) and flow rate (about 5 to 12 m/s), and then the pulp is very The fast speed rotates along the cylinder wall to generate centrifugal force. Under the action of centrifugal force and gravity, the coarser and heavier ore particles are thrown out.
Hydrocyclones are mainly used for classification, separation, concentration and desliming in the mineral processing industry. When the hydrocyclone is used as a grading device, it is mainly used to form a grinding and grading system with a mill; when used as a desliming device, it can be used for desliming in a gravity separation plant; when used as a thickening and dewatering device, it can be used to remove beneficiation tailings After being concentrated, it is sent to fill underground mining tunnels.
The hydrocyclone has no moving parts and has a simple structure; the production capacity per unit volume is large and the area is small; the classification efficiency is high (up to 80% to 90%), the classification particle size is fine; the cost is low, and the material consumption is low.
