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Cleaning Method for Ceramic Vacuum Filter |
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08 Jun, 2017 |
Ultrasonic Cleaner |
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Ceramic vacuum filter is a kind of efficient and energy-saving solid-liquid separation equipment, which is widely used in ore-dressing process. Ceramic filter plates are the core components of vacuum disc filter, use composite porous ceramics as a new-type filter medium. In order to maximize the production efficiency, it's significant to choosing a proper cleaning method including ultrasonic cleanng for ceramic filter equipment. Immersible ultrasonic transducers are commonly used in mineral dressing process and realize excellent cleaning effects over conventional cleaning equipment and solvents. The combined cleaning system consisting of vibration box and acid washing fully ensures the unobstructed micropores on ceramic disc plates and the high efficiency of filtration.
Cleaning methods of ceramic vacuum filter
The cleaning methods of ceramic filter plates can be divided into physical methods and chemical methods. The physical methods include backwash and ultrasound, chemical methods include oxidants, acid-base cleaning, etc. Generally, The way chosen depends upon differences in material, type of dirt and degree of contamination.
1) Backwash: compressed air seeps out from the inside of filter plate under positive pressure, remove any residue and small particles in micro pores on surface caused by the gap between filter plate and scraper. If the backwash pressure is too high, the filter plate is prone to damage, and if it is too small, the backwash power is insufficient for cleaing, usually controlled at around 0.15MPa.
2) Acid cleaning: mainly consists of an acid storage tank, acid pump, cleaning pipelines, etc. It generally uses about 1% acid containing to chemically clean and dissolve fine particles and scaling substances, and combines with ultrasonic cleaning to form a joint cleaning device, promot the coordination between chemical and physical interactions to obtain great cheaning result.
3) Ultrasonic cleaning: include ultrasonic generator, ultrasonic immersible transducer, and related connecting cables. In the joint cleaning stage after shutdown of ceramic filter machine, the ultrasonic generator sends high-frequency signals, which are converted into high-frequency mechanical oscillation waves through ultrasonic transducer and continuously impact the ceramic filter plate, cause the dirt on surface and gaps of disc filter plate to quickly peel off, achieve the goal of quickly unblock micropores and clean the surface of ceramic plate.
Ultrasonic cleaning for vacuum disc filter
The ultrasonic cleaning system for vacuum ceramic disc filter mainly consists of ultrasonic power, immersible transducer and auxiliary cables. The vibration box is installed on both sides of the filter plate, the output line comes out of the hollow tube and connects to the generator. During cleaning process, High-frequency oscillation produce tens of thousands of tiny vacuum bubbles, these bubbles generate and grow in the negative pressure zone formed by the longitudinal propagation of ultrasonic waves, and quickly close in positive pressure zone. The process is known as cavitation effect, the tiny bubbles can generate instantaneous high pressure exceeding atmospheric pressure when closed. The continuously generated instantaneous high pressure, like a series of small explosions, continually impacts the surface of ceramic disc plate to peel off the fouling, and purify and dredge the ceramic filter plates. , some solid substances that have not been cleaned and adhered to the filter plates are dissolved and completely separated from the filter medium by combining ultrasonic cleaning and chemical cleaning. However, there are many factors that affect the cleaning effect of submersible ultrasonic cleaner, mainly including frequency, power density, temperater, viscosity of liquids, etc, please learn more details at: Ultrasonic Cleaning Effect
Mounting method of ultrasonic immersible transducer
It can be divided into two types based on different mounting method: Inserted type and lift type
1) Inserted-type immersible transducer consists of an ultraosnic vibration box, a screw, nuts, etc. The screw is welded to the stainless steel box, and the transducer box is fixed between two ceramic filter plates. The installation height of screw rod can be adjusted to ensure that the ultrasonic box is located on the running trajectory of filter plates. In the joint cleaning stage, the ceramic filter plate moves in a low-speed circular motion with the rotation of rotor, and passes through the working area of ultrasonic immersible transducers. The mechanical waves emitted by cleaning transducers are transmitted into liquid, which acts on the porous filter plates to complete cleaning work.
2) lift-type immersible transducer consists of an ultrasonic vibration box, a lifting device and upper and lower limit switches. The ultrasonic box is rigidly connected to the lifting rod. During operation, the lifting device drives the lifting rod and immersible transducer to rise, and stop at the upper limit position, cleaning box is above the liquid level of tank. In the joint cleaning stage, the lifting device drives the lifting rod and immersible transducer to descend, stop at the lower limit position, and the cleaning box is below the level of cleaning solution. At this point, ultrasound begins to work, the ceramic filter plate moves in a low-speed circular motion with the rotation of rotor, pass through the working area of ultrasound wave in sequence. The cavitation bubble penetrate fine gaps and tiny holes, and clean the complex shaped micropores inside the filter ceramic plate. As the rotor rotates back and forth, the cleaning task will be successfully completed. Finally the ultrasonic cleaning box is raised above the liquid level of tank again.
It's easy to see from the above structure that the Inserted-type ultrasonic cleaner may have cracks in outer shell of metal box due to long-term immersion in solution with strong corrosiveness of many materials filtered by ceramic filter. Once the liquid penetrates into transducer box, it will cause a short circuit or overload in electrical circuit. In addition, the immersible transducer is fixed in slurry tank which increases the difficulty of disassembly and maintenance. The fixed installation position also creates many dead corners in tank, and difficult to clean. The lifting immersible transducers have many obvious advantages, they only enter into cleaning tank when needed. At the same time, replacement, disassembly and flushing work are very convenient, greatly improve the stability and reliability of vacuum ceramic filter system. However, the complex structure and high-degree automation level of lifting-type ultrasonic immersible transducer will increase the manufacturing cost of ceramic vacuum filters. Each factory should choose a suitable ultrasonic cleaning solution based on their own actual situation.
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