Polygonmachine PDH Series – Dewatering Screen and Hydrocyclone Systems

What is a Dewatering Screen?

A dewatering screen is a highly beneficial piece of equipment that removes surplus water from bulk material. It does this by adding high-frequency vibration to a sloping screen deck, on which water can drain while solids are retained and discharged.
The technology is of critical value to the mining, aggregates, sand treatment, and recycling industries, where moisture content needs to be controlled to facilitate processing, transport, and secondary processing of material.

Gravity and capillary action is the principle through which the dewatering screen operates. High speed is caused by oscillations, and consequently, there is high-speed draining of water and little material loss. Less processing time, less operating expense, and high efficiency are realized from dewatering screens relative to conventional drying operations.

At Polygonmachine, we are committed to the bespoke design of dewatering screens that deliver world-leading drying quality but are incredibly durable against demanding applications. We engineer our solutions to meet and surpass the most demanding requirements in markets around the world.

Dewatering screens strip excessive water from material after washing and separation operations. Under gravity, water flows backward due to high-frequency and overall upward-inclined vibration, while solid matter dries to lose its high moisture content.

Model	Width x Length (mm)	No. of Decks	Power @50Hz (kW)	Weight (kg)	Max Feed Size (mm)	Typical Moisture Content Reduction (%)
PDS 1224	1200×2400	1	2×2.88	1800	10	8–15
PDS 1824	1800×2400	1	2×7.35	2645	10	8–15
PDS 1840	1800×4000	1	2×6.1	4092	10	8–15

How Does a Hydrocyclone Work?

A hydrocyclone is a conical separation machine that utilizes high centrifugal action to separate particles in a liquid. It has no moving parts within, making it simple, effective, and extremely durable.
Slurry is pushed tangentially at pressure into the hydrocyclone, where it creates a swirling vortex. The heavier particles are pushed towards the periphery in the direction against the wall and out by way of the underflow nozzle through centrifugal force, while lighter fluid and fines are attracted toward the centre and out through the overflow pipe.

Hydrocyclones are also found to have broad uses in mineral processing, mining, oil and gas, and wastewater treatment plants. Its major uses include particle classification, desanding operation, and slurry dewatering.

Our hydrocyclone solutions at Polygonmachine are created to achieve the best performance with superior separation performance, minimal maintenance, and long life. For fine particle recovery or thickening applications, our hydrocyclones ensure stable operation under various operating conditions.

Hydrocyclones are efficient yet low-maintenance equipment that employs centrifugal action to separate solid particles from liquids based on the principle of difference in density. Because of their conical structure, they generate a high-speed circular motion that propels heavier particles outward to be ejected from the bottom, and lighter particles remain at the center and flow through the top.

Model/Size (inches/mm)	Typical Particle Recovery (mesh/µm @ SG)	Lining Options	Construction Materials	Cone Angles	Primary Application
4-100mm	+200 mesh (75µm) @ 2.7 SG	Rubber, Urethane	Ni-hard, Hi-chrome	Multiple	Classification, Desliming
12-300mm	400 mesh (38µm) @ 2.7 SG	Rubber, Ceramic	Ni-hard, Hi-chrome	Multiple	Fines Recovery
36-900mm	625 mesh (20µm) @ 2.7 SG	Rubber, Urethane	Ni-hard, Hi-chrome	Multiple	Specialty Fines

Dewatering Screen for Sand Applications

One of the most common uses of a dewatering screen is sand processing. Sand dewatering screens are specifically constructed to remove as much water as possible from sand slurry after washing or wet classifying.
Water levels should be reduced to a minimum in sand production plants in a bid to attain maximum stockpile condition, and final product quality. Water in sand incurs handling costs and may lead to production delays. Installation of high-efficiency dewatering screens will ensure sand is dry enough for transportation, storage, and use in construction activities.

Polygonmachine has high-capacity dewatering screen sand systems that are designed to high standards of performance. Our design yields quick dewatering, lowest loss of fines, and lowest maintenance downtime, attributes that lead to highest profitability to sand producers.

Assume a sand washing plant:

Sand is in slurry form.

The hydrocyclone centrifuges the slurry, spuing out heavier sand particles through the underflow.

But this discharge still contains 25–30% moisture.

The wet sand is pumped to the dewatering screen.

The vibrating screen action weeps away excess water, reducing moisture down to 8–15%.

The sand produced is dry enough to be stockpiled directly.

This system not only saves water but also offers excellent product quality.

Hydrocyclone Separator: Definition and Applications

The application of hydrocyclone is that which is referred to as hydrocyclone separator — centrifugal separation of solids from liquid suspensions.
Hydrocyclone separators are very versatile and are largely used for:

Classification of particles by size or density

Thickening and dewatering of slurry

Desanding and desilting operations

Clarification of wastewater

Hydrocyclone separators can be utilized to treat fine, coarse, or mixed-size slurries based on design parameters.
Polygonmachine offers different hydrocyclone separators for application in various industries to provide maximum performance for every individual process requirement.

While hydrocyclones will separate water from solids based on density, the discharge from the resulting separation can still contain moisture. That is where dewatering screens enter the picture.

Advantages of Using the Two in Combination:

Hydrocyclone discharge is pumped to the dewatering screen, with moisture content reduced to 10–15%.

Provides outstanding fine material recovery.

Decreases drying time, with dry, stackable product produced.

Provides significant savings in water and energy consumption.

Such a mixture is now standard practice in sand washing plants, aggregate plants, wastewater treatment works, and mines.

Hydrocyclone vs Centrifuge: A Technical Comparison

When it comes to separation equipment, most industries prefer hydrocyclones vs centrifuges.
Though both make use of centrifugal forces, there are a few differences:

Hydrocyclones cost less, contain fewer moving parts, and hence lower acquisition and maintenance costs. They’re most appropriately used for bulk separation operations where ultrafine separation is not required.

Centrifuges achieve greater accuracy in separation and are used wherever high accuracy or efficiency of dewatering is of the essence. Centrifuges are, however, more costly to purchase, operate, and maintain.

In summary:

Where low-cost, high-throughput separation is paramount — hydrocyclones are the solution.

Where ultimate recovery of solids and recovery of fines is desired — centrifuges might be the solution.

Our technical professionals at Polygonmachine advise our clients in selecting the best technology based on project requirements, operating conditions, and economics. From hydrocyclone use to centrifuge technologies, our technical guidance and customized solutions are provided.

Conclusion

Hydrocyclones and dewatering screens are both very essential equipment used in material processing facilities.
Dewatering screens suit best for expediting the dewatering of solids like aggregates and sand, whereas hydrocyclones are engineered for thickening and separating slurries by the process of centrifugal separation.
Through a clearer understanding of operating principles, uses, and differences in performance among these technologies, companies are able to improve process, save them money, and increase productivity.

Here at Polygonmachine, we are dedicated to delivering world-class, state-of-the-art solutions to global dewatering, classification, and slurry separation needs. Call us today to learn how our equipment can increase your efficiency and profitability levels.