Reasons for low working efficiency of hydrocyclone

The hydrocyclone is an effective ore classification equipment. The pulp is fed into the cyclone along the tangential direction at a certain speed for rotating motion. Under the action of centrifugal force, the coarser particles are thrown to the wall of the vessel, move downward in a spiral trajectory, and are discharged from the grit chamber to become coarse-grained products; the finer particles and most of the water are discharged from the overflow pipe in an inner spiral trajectory, and To achieve the purpose of separation and classification.

In the production process, the factors affecting the working efficiency of the hydrocyclone mainly include ore properties, structural factors and process operation factors. Below, I will take you to understand in detail how various factors affect the working efficiency of the hydrocyclone, so as to help you use the hydrocyclone correctly.

Part 1 The nature of the ore

The ore properties mentioned here mainly refer to the density, particle size composition and slurry concentration of the ore.

The higher the density of the ore, the finer the classification size. When the slurry concentration is high and the mud content is high, its viscosity and density increase, which increases the movement resistance of the particles and makes the classification size coarser, and vice versa. Therefore, when the mud content is high, it is necessary to de-slime in advance. Appropriate pulp concentration is usually determined by beneficiation tests according to specific conditions.

Part2 Structural factors

In terms of structure, the factors affecting the working efficiency of the hydrocyclone mainly include the diameter and height of the cylinder, the size of the ore feeding port, the diameter of the grit chamber, the diameter and depth of the overflow pipe and the size of the cone angle.

1. Cylinder diameter and height

The diameter of the cylinder is the main size of the hydrocyclone, and it has a certain relationship with the dimensions of other components, which determines the separation particle size and production capacity of the hydrocyclone. When the ratio between the feeding pressure, the feeding port, the overflow port and the diameter of the cyclone remains unchanged, the production capacity of the cyclone will increase with the increase of the diameter of the hydrocyclone, and the separation particle size will also increase with the diameter of the hydrocyclone. The diameter increases and becomes thicker.

Therefore, most plants will choose the size of the hydrocyclone according to the required overflow particle size, or even use multiple hydrocyclones in parallel.

The height of the column mainly affects the length of time that the slurry is affected by centrifugal force, which has a certain impact on the work efficiency. In general, the height of the hydrocyclone cylinder should be 0.6-1.0 times the diameter. The higher the height of the column, the finer the separation particle size, but if it exceeds a certain limit, it will lose its effect due to the increase of the ore pressure loss.

2. Feeding port size

The size of the feeding port will affect the working efficiency and production capacity of the hydrocyclone. Too large or too small feeding port is not conducive to the classification effect. If the feeding particle size is coarse and the feeding pressure is low, the ratio of the feeding port to the diameter of the hydrocyclone can be slightly larger, generally 0.16-0.20 is appropriate; and if the feeding granularity is finer, the feeding pressure is higher , the ratio of the diameter of the feed to the hydrocyclone is usually maintained at 0.14-0.16.

In addition, the shape of the feeding port (often rectangular) and the feeding method (tangential or involute) also have a certain impact on the work efficiency.

3. Grit nozzle diameter

Generally, the diameter of the grit chamber is large, the overflow volume is small, and the overflow particle size becomes finer, while the increase of the grit volume, the concentration becomes lower, and the fine particles increase, but it has no obvious effect on the processing capacity.

The diameter of the sand settling nozzle is small, the concentration of sand settling is high, the discharge volume of the settling sand is reduced, and the phenomenon of "running coarse" will appear in the overflow.

The suitable diameter of the grit chamber should be such that the sand is discharged in an umbrella shape, with an included angle of 40°-70°, and the ratio of the diameter of the grit chamber to the diameter of the overflow pipe is generally 0.4-0.8.

4. Overflow pipe diameter and depth

The diameter of the overflow pipe should be proportional to the diameter of the hydrocyclone. When the diameter of the overflow pipe is increased, the overflow volume will increase accordingly, the overflow particle size will become coarser, the fine-grained grade in the sedimentation will decrease, the concentration of the sedimentation will increase, and the classification efficiency will decrease. In addition, the ratio of the depth of the overflow pipe to the height of the hydrocyclone cylinder should also be kept at 0.7-0.8. Too deep or too shallow will cause the overflow granularity to become coarser and the fine-grained content in the sand to increase, thus affecting the work efficiency.

5. Cone angle size

The size of the cone angle has an important influence on the working efficiency of the hydrocyclone. The cone angle is small, the cone is long (the distance between the overflow port and the sand settling port is large), and the classification volume is increased, which can strengthen the classification process of mineral particles in the hydrocyclone, which is conducive to the separation of fine-grained materials. When used for fine-grain desliming, the cone angle is generally 10°-15°, and when used for coarse-grain classification, the cone angle is generally 20°-45°.

Part 3 Process operation factors

In the production process, the process operation factors that affect the working efficiency of the hydrocyclone mainly include ore feeding, overflow and sand discharge. The parameters are within a reasonable range to ensure the stable operation of the hydrocyclone.

1. Feeding pressure, concentration, particle size composition

The ore feeding pressure mainly affects the processing capacity and grading size of the hydrocyclone. The feeding pressure is increased, the slurry flow rate is accelerated, and the influence of viscosity is reduced, and the classification effect of the hydrocyclone is improved. When dealing with coarse-grained materials, most plants use a low pressure of 49-98KPa, while when dealing with fine-grained and muddy materials, a high pressure of 98-294KPa is used.

The ore feeding concentration and its particle size composition will directly affect the concentration and particle size of the final product. The particle size of the product is coarser.

2. Discharge of overflow and grit

The ideal working state of the hydrocyclone should be that the sand is sprayed out in an umbrella shape. Therefore, the angle of the umbrella surface should not be too large, and it is appropriate to just spread out. When used for concentration operations, the sand is discharged in a rope shape with a higher concentration. When used in dewatering operations, the sand is discharged in a larger umbrella shape, and the overflow has the least solid content.

The above are the three major factors that affect the working efficiency of the hydrocyclone. It is worth noting that maintaining the working efficiency of the hydrocyclone is a systematic project, and each factor is not only related to each other, but also restricts each other. The selection plants must be considered comprehensively and cooperate closely in order to obtain the ideal working efficiency.

Offered by Huatao Group

2022-03-21