Rubber belt filter

The Tilting Pan Filter is predominantly employed in the phosphoric acid industry and, to some extent, in the washing of phosphate rock. There was a traditional rivalry over the years between the Pan and Belt Filter which now, owing to the substantial progress in rubber technology, swings in the favor of the later. The operation of Tilting Pan Filters is based on a series of horizontal independent... 

A belt filter consists of an endless reinforced rubber belt, with drainage hole along its centre, which supports the filter medium. The belt passes over a stationary suction box, into which the filtrate is sucked. Slurry and wash water are sprayed on to the top of the belt. 

Figure 11.11. Continuous horizontal vacuum filters especially suited to free settling and draining solids, (a) Principle of the conveyor belt filter units may operate up to 0.S m/sec with a cycle time up to 10 min and produce cake thicknesses up to 15 cm. (b) Showing the construction of a grooved rubber belt support for the filter cloth of the belt filter (Purchas, 1981). (c) Rotating horizontal vacuum filter the unit has readily accessible piping and is amenable to thorough washing of free draining solids (Dorr-Oliver Inc.).

Belt filter, horizontal vacuum 316 s/s for parts contacting the liquid, including drive and motor but excluding vacuum equipment, platforms, tanks, pumps and piping for feed and wash. FOB cost = 400000 for an effective filter area = 9 m with n = 0.64 for the range 10-60. L-i-M = 2.2-3.2. L/M = 0.42. Alloy factors 316 s/s, X 1.00 rubber-coated, X 1.0 c/s, X 0.60. Complexity factors excluding vacuum auxiliaries, X 1.00 including vacuum auxiliaries, X 1.3. 

Several equpment vendors supply the continuous, rubber belt type filter dqricted in Figure 11.17. Variations in design are usually directed at reducing the fiiction betwe the belt (with the supported cake mass) and the vacuum box. Attention is given to the use of low-fiiction materia (PTFE) for the contact surfiices. Air or filtered water may be directed at the inter ce between the sliding surfiice area and the box. 

Increases of the rubber belt width leads to increased belt cost, which can be 22-40% of the overall cost of the filter. Cost considerations, and the need to find a replacement for... 

F ure 7. Filtering partition for a belt filter 1 - rubber beit 2 - slots 3 - grooves 4 -filtering cloth 5 - cord 6 - edges of rubber belt. 

One important variation of this type of filter is based on replacing the rigid outer wall necessary for containing the feed and the cake on the rotating table by an endless rubber belt. The belt is held under tension and rotates with the table. It is in contact with the table rim except for the sector where the discharge screw is positioned, where the belt is deflected away from the table... 

From the final pond the concentrated brine (Table 1.3) with a density of about 1.25 g/cc was pumped nearly 4.8 km (3 mi 1.5 mi in 1967, Gadsby, 1967) to the processing plant in the town of Silver Peak. The plant had been converted from a silver ore cyanide-leach plant that had operated there from 1864-1961. In the conversion all of the tanks and settlers were rubber lined to reduce iron contamination in the product, and considerable new equipment was added. The solar pond brine was first reacted with lime to remove most of the residual magnesium and some of the sulfate and borate ions, and then a small amount of soda ash was added to precipitate most of the calcium from the lime reactions. The slurry from these operations was settled and filtered, and the overflow solution sent to storage tanks. From there the brine was pumped through filter presses to be totally clarified, and then heated to 93°C (200°F lithium carbonate has an inverse solubility) and reacted with dry soda ash and hot wash and make-up waters to precipitate the lithium carbonate product. Extra water was added to prevent salt from crystallizing, since the pond brine was samrated with salt. The lithium carbonate slurry was thickened in a bank of cyclones, and the underflow fed to a vacuum belt filter where it was washed and dewatered. The cyclone overflow and filtrate were... 

Modular Type Filter With the so-called modular filter (Figure 18.24) the endless rubber carrying belt with its trough shape is replaced by trays of stainless steel... 

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