Belt Filter Cloth

Belt Filter Cloth is used in Horizontal Belt Filters which are the most commonly used vacuum filters in the industry due to their flexibility of operation, adaptation to corrosive slurries and suitability to handle large throughputs.The development of the Horizontal Belt Filters for the chemical process industries was closely associated with the progress in rubber technology since they incorporate an endless and thick rubber belt of a complex design to support the cake retained by the filter cloth. The Best filter cloth retains the cake and moves together with the belt. Nowadays, with some exceptions, they are made from synthetic materials such polypropylene or polyester with monofilament or multifilament yarns and with sophisticated weaves. The entire subject of filter cloth and its selection will be discussed in a separate section that was not yet constructed.

Belt Filter Cloth Selection Criteria

• For solids that are fast settling and cannot be kept as a homogenous slurry in bottom or side feed filters such as Drum or Disc Filters.
• When long drying time is required to reach asymptotic moisture in the cake. On Drum Filters, for example, the ratio of dry to form cannot normally exceed 1.5 since it is determined by its geometry and the number of circumferential compartments.
• When very short cycle times are required for fast dewatering cakes such as phosphate slurry.
• If a clear filtrate is required right from the start it is good practice to form a thin heel that serves as filter medium over the exposed cloth.
• When intensive cake washing is required since belt filters make it possible to apply counter-current washing. On Drum Filters, for example, the time available for washing is rather limited due to its geometry.
• When cakes tend to crack under vacuum measures such as a flapper, compression blanket or pressure roll may assist in sealing the cracks thus avoiding loss of vacuum.
• When such measures are used it is necessary to make sure that the belt supporting system can take these extra vertical loads.
• When scale formation due to flash evaporation is a problem or filtrate temperature must be maintained a vacuum box steam jacketing may be provided.
• When the cake tends to clog the cloth its continuous removal after cake discharge enables dislodging of particles by thorough washing of the cloth on both sides with high impact nozzles.