Disc pressure filters are commonly used in flotation processes. The structure of a disc pressure filter consists of five main parts: a pressure chamber, a disc filter, a scraper conveyor, a sealed discharge valve, and an automatic control device. The following is a detailed description:

1. Pressure Chamber

The pressure chamber is a pressure vessel where the entire pressure filtration process takes place. One end of the chamber has a fixed end cap, and the other end has a movable end cap to accommodate the filter and scraper conveyor. General maintenance is carried out inside the chamber, which is equipped with lighting, a maintenance platform, and a lifting beam. For easy access to personnel and parts, there are one ø1200mm and one ø900mm manhole. A sight glass is also installed for easy observation of the chamber’s operation. A safety valve is installed on the top of the chamber.

2. Disc Filter

The pressure chamber contains the disc filter. The disc filter under pressure differs significantly from a typical disc vacuum filter. First, to accommodate the increased pressure differential, the pressure resistance of the filter discs is correspondingly increased. Second, to reduce compressed air consumption, the number of filter elements is increased, and the immersion depth is also increased accordingly, allowing the liquid level in the filter tank to reach the same level as the centerline of the main shaft. Therefore, the main shaft sealing device of the disc filter has been improved. To accommodate the increased filtration intensity, the cross-section of the filtrate pipe has been doubled and placed on the outer ring of the main shaft for easy replacement. To address particle stratification in the filter tank, a specially developed axial-flow high-power agitator enhances convection between the upper and lower layers of the slurry in the filter tank, thereby improving the filtration effect.

The filter discs are generally made of fiberglass or stainless steel, and the filter cloth is made of specially woven stainless steel wire. During operation, the filter discs rotate within the coal slurry in the tank, and under the action of compressed air, the coal slurry forms a filter cake on the filter discs. The filter cake is dehydrated at the top of the filter discs and carried to the discharge position. A special guiding device is located at this position, equipped with a discharge scraper. The distance between the scraper and the filter disc is maintained between 2-4 mm. This discharge method ensures a filter cake removal rate of over 95%. A back-blowing device is also included; when the filter cake thickness is less than 5 mm, back-blowing is required for discharge.

3. Scraper Conveyor

The main purpose of the scraper conveyor is to transport the dewatered filter cake to the discharge port at the bottom of the pressure chamber. The main body of the scraper conveyor is a common scraper conveyor with a double-sided circular chain structure and lower chain transport. Measures are taken during operation to prevent chain slippage; discharge is at the head of the machine; anti-stacking devices are installed at the head and tail of the machine; the bottom of the trough is lined with cast stone to prevent sticking.

4. Sealed Discharge Device

The sealed discharge device is an important component of the pressure filter. Its function is to reliably discharge material under sealed conditions, thereby smoothly discharging the dewatered filter cake and saving compressed air consumption. Currently, the main type used is a dual-chamber, dual-gate alternating sealing discharge device. The two gates are hydraulically driven, and the seals on the gates use inflatable rubber sealing rings. During pressure filtration, the filter operates continuously, while the upper and lower chambers discharge material intermittently, with a short discharge cycle of 50 seconds.

5. Automatic Control Device

The automatic control device consists of three parts: sensors, transmitters and controllers, and regulators and actuators. The pressure filter is installed inside a pressure vessel, operating under harsh conditions with frequent mechanical movements, short discharge cycles, tight connections, and strict interlocking.

This equipment is equipped with a technologically advanced, fully functional, reliable, and flexible parameter monitoring system to ensure the pressure filter operates at high efficiency. The pressure filter has three control modes: local, centralized, and automatic. The first two are used for equipment maintenance and adjustment, while the last is suitable for production operation.