Working principle of hydrocyclone

Hydrocyclone is a device that uses centrifugal force to accelerate the settling of mineral particles, separating solid particles from the slurry liquid. In addition to classification operations, hydrocyclones can be used in thickening, dewatering and ore sorting processes.

First, the hydrocyclone composition and structure

The upper part of the hydrocyclone is a cylinder and the lower part is an inverted cone. The upper part of the cylinder is sealed, and there is no bottom plate in the middle. In the middle of the bottom plate, there is a short tube overflow pipe connecting the upper and lower parts. The ore pipe is connected to the lower part of the base plate along the tangential direction of the cylinder, and the overflow discharge pipe is connected to the upper part of the cylinder. At the bottom of the cone is a sand sinker for the mouth of the mine. The sand sinker and the cylinder are usually lined with wear-resistant rubber, silicon carbide, polyurethane or pyroxene cast stone to reduce wear and facilitate replacement after wear.

Second, the working principle of hydrocyclone

The working principle of hydrocyclone is mainly centrifugal sedimentation. Under pressure, the slurry enters the hydraulic cyclone shell along the cutting line and undergoes rotary motion. Coarse particles or high-density particles in the slurry enter the periphery of the rotating flow through a larger centrifugal force, while flowing downward with the slurry, and eventually discharged from the bottom of the sand sedimentation port, forming sand; fine particles or low-density particles in the centre of the rotating flow of a smaller centrifugal force, flowing with the liquid, and ultimately discharged from the overflow pipe overflow.

Third, the advantages and disadvantages of hydrocyclone

The main role of hydrocyclone in the beneficiation process is: first, as a grading device in the grinding circuit, especially as a grading device for fine grinding; second, slurry and concentration. In actual production, it needs to be selected according to the nature of the ore to be processed and the beneficiation environment.

Advantages:

(1) High grading accuracy, because the centrifugal force is many times greater than gravity, so the lower limit of the particle size of grading is reduced, and it can separate the finer size of the ore particles;

(2) High classification efficiency, especially when the classification size is very fine, the classification efficiency of hydrocyclone is significantly higher than other classification equipment;

(3) Simple structure, no moving parts, easy to manufacture and maintain;

(4) Strong production capacity, small footprint, suitable for a variety of working environments.

Disadvantages:

(1) large energy consumption, hydrocyclone feed pump for mining consumes large amounts of electricity, about 5 to 8 times as much as other classification equipment;

(2) Fast wear and tear of the equipment, especially the fastest wear and tear of the feed port and sand sinking port, which need to be replaced frequently;

(3) The fluctuation of feeding pressure, feeding size and feeding quality can easily affect the working index of hydrocyclone.

Common faults and solutions

1: Large fluctuation of feed pressure

In the production process, the feed pressure will affect the processing capacity and classification size of the hydrocyclone. Generally speaking, the feed pressure of hydrocyclone should be kept stable according to the requirements, and should not produce large fluctuations, otherwise it will damage the performance of the equipment and affect its classification effect. The reason for large fluctuations in feed pressure is usually a drop in pump tank level or air traction resulting in insufficient feed to the pump, or clogging of debris in the pump. The drop in feed pressure after long-term operation of hydrocyclone is mainly caused by pump wear.

  1. If the pump tank level drops caused by fluctuations in the feed pressure, you can increase the level, close one or two cyclones or reduce the pump speed to adjust;
  2. Pump clogging or wear caused by fluctuations in feed pressure, the pump should be overhauled.

Fault two: hydrocyclone clogging

Determine whether the hydrocyclone is clogged mainly by observing the operation of the hydrocyclone overflow and underflow discharge is smooth to judge. When there are more coarse particles in the overflow, the overflow and underflow flow is reduced or the underflow is disconnected, and the sedimentary sand is discharged in the form of a column, it means that the hydrocyclone is clogged. In addition, if the hydrocyclone shakes violently for a long time, it also indicates that the hydrocyclone is clogged.

  1. If the overflow, the underflow flow decreases, it may be the hydrocyclone inlet clogging. In this case, the feed valve of the clogged hydrocyclone should be closed, and the clogging should be removed and cleared;
  2. If the bottom flow is reduced or cut off, the bottom flow port is clogged. At this time, you can remove the flange, remove the bottom flow mouth debris.
  3. In order to prevent clogging, the hydrocyclone group feed pool can be set up to prevent coarse debris facilities (such as debris removal screen). At the same time, the feed pool should be emptied in time when stopping to avoid clogging when travelling again due to sedimentation and high concentration.

Failure bottom flow concentration and discharge abnormalities

During operation, hydrocyclone operators should frequently observe the cyclone underflow discharge status and regularly test the underflow concentration and fineness. If the underflow concentration fluctuates or the underflow is clamped, it should be adjusted in time. Under normal operating conditions, the hydrocyclone underflow discharge should be umbrella. If the underflow concentration is too high, the underflow is column or intermittent block discharge.

  1. High underflow concentration may be caused by high concentration of feed slurry or too small underflow opening. You can add appropriate amount of water at the feed first. If the underflow concentration is still large, it is necessary to replace the larger underflow opening.
  2. If the underflow is discharged in the form of umbrella, but the concentration of underflow is less than the required concentration of production, it may be caused by the low concentration of feed material. At this time, the feed concentration should be increased.
  3. Bottom flow clip fine may be caused by bottom flow mouth wear, bottom flow calibre is too large, overflow pipe diameter is too small, pressure is too high or too low. Adjust the pressure first, and then test whether the bottom flow mouth is worn or replace the smaller size of the bottom flow mouth, and gradually adjust to the normal production state.

Failure four: overflow concentration and fineness abnormality

In the operation process, hydrocyclone operators also need to regularly test the cyclone overflow concentration and fineness. The increase in overflow concentration or overflow thickness is usually due to the increase in mine concentration and the blockage of the bottom outlet.

  1. If you find that the overflow runs thick, you can first test whether the bottom outlet is clogged, then test the concentration of the ore feed, and then adjust according to the specific situation. If the bottom outlet is clogged, open the bottom outlet to clear the clog.
  2. If the overflow concentration is small and the fineness is fine, you can reduce the pressure or adjust the feeding concentration, or you can meet the requirements by replacing the small sand sinker. If the overflow concentration is large, fineness is coarse, you can increase the pressure and adjust the concentration of ore or replace the large sand sinker to meet the requirements.

Failure five: sand sinking nozzle in the form of spray or rope

Under normal circumstances, the sinking sand of the hydrocyclone is discharged in the form of an umbrella, and the angle of the sinking sand is between 10°-20°, and the concentration is about 75%, which is the ideal working condition of the hydrocyclone. If the sand-sinking nozzle is spray-like, the dispersion angle of the sand is too large, indicating that the size of the sand-sinking nozzle is too large. If the sand-sinking nozzle is rope-like, it may be because the feed concentration is too high, the size of the sand-sinking nozzle is too small, the sand-sinking nozzle is partially clogged or the density of the slurry is too low.

  1. When the sand-sinking nozzle is in the shape of spray, it can be adjusted by replacing the small sand-sinking nozzle.
  2. When the sand-sinking nozzle is rope-like, you can increase the size of the sand-sinking nozzle appropriately, and stop the cyclone operation to clean up the clogging phenomenon.

The above are the reasons and countermeasures for the common failures of hydrocyclone. In order to make the equipment stable and efficient operation, in addition to choosing the type of equipment that meets the ore dressing process, routine maintenance is also particularly important

The main factors affecting the operating effect of hydrocyclone

Hydrocyclone overflow particle size and concentration, mainly related to its internal structure parameters and external parameters; the former with the diameter of the hydrocyclone, feed pipe diameter, overflow pipe diameter, diameter of the sedimentation port, as well as the structure and material of the cyclone; the latter with the feed flow rate, feed pressure, feed concentration, density of ore, media density, etc., and so on.

In the nature of the ore, grinding conditions, equipment selected under the premise of which feed pressure and feed concentration is the most important factor affecting the efficiency of the classification effect, the process affects the two main factors are slurry pump speed, add water; feed pressure and slurry pump speed related to the oncentration of the ore and the size of the added water, because of the equipment factors and the movement of the sedimentation interference law, both can only be adjusted within a limited range The overflow particle size is the reflection of the water and the water and the water and the water. The overflow particle size is the most important factor to reflect the hydrocyclone working condition and classification effect.