Drum vacuum filters

One of the oldest filters applied throughout the chemical processing industry is the rotary vacuum drum filter, which is illustrated in Figure 8. This machine belongs to the group of bottom feed configurations. Rotary drum filters are typically operated in the countercurrent mode of operation. The principle advantage of these machines is the continuity of their operation. 

Figure 16-5 A continuous belt drum filter. This works on the same principal as the vacuum drum filter. 

Rotary Vacuum Drum Filters Designed By M/s. Eimco, USA... 

Vacuum drum filter F G Ed high to med. — medium high medium medium high high medium... 

Filtration is a unit operation commonly employed nowadays in biotechnological processes. In this unit operation, a filter medium acts as a physical barrier to particles larger than its pores. Traditional filtration devices such as filter presses and rotary vacuum drum filters have so far found no application for the separation of animal cells. Nevertheless, membrane filters are commonly employed, as well as some alternative filter designs such as spin-filters. In the next sections, the most common types of filters used for animal cell separation will be discussed. 

The filter press is to be replaced by a rotary vacuum-drum filter with negligible filter-medium resistance. This rotary filter can deliver the filtrate at a rate of 1000 lb/h when the drum speed is 0.3 r/min. Assuming the fraction submerged and the pressure drop are unchanged, what drum speed in r/min is necessary to make the amount of filtrate delivered in 24 h from the rotary filter exactly equal to the maximum amount of filtrate obtainable per 24 h from the plate-and-frame filter ... 

FIGURE 14.9 Rotary vacuum drum filter (Example 14.6). 

After precipitation is complete, the slurry is pumped to vacuum drum filters where a neady complete liquid—solids separation is accomplished. The liquid is dilute sodium sulfide solution, which is concentrated by evaporation to a flaked 60 wt % sodium sulfide product. The filter cake is a 60 wt % strontium carbonate soHd which is fed to a carbonate dryer. After drying, the strontium carbonate product is cooled, ground, and screened for packaging. 

Vacuum drum filters, 319 air flow rates, 328 applications, 332 cycle design, 328 flowsketch, 326 laboratory test data, 312 minimum cake thickness, 328 operation, calculation example, 312,... 

Cross-sectional end view of rotary vacuum-drum filter. (Eimco Corporation.)... 

Filtration can include filter presses, rotary vacuum drum filters, and variations on synthetic membrane... 

Precoated rotary vacuum drum filters (Fig. 6) are used by filtering a slurry of filter aid and water first, then subsequent product filtration. Difficult filtering materials, which have a tendency to blind, are removed with a doctor blade. Precoat is removed along with the slurry to expose a new filtration surface each cycle. 

One of several problems that confront the procedure, for example, is the design of a suitable filter. Possibly vacuum drum filters could be used for liquids of low viscosity, but high-viscosity liquors will require new designs provided with ways and means for continuous displacement of the carbon cake from the filter leaf. 

A study of the wet circuit operations, with the technical assistance of Asturiana de Zinc, showed that the majority of the zinc loss was due to the low wash efficiency of the existing vacuum drum filters. In addition, it was observed that there still was an amount of recoverable zinc in both the lead-silver and jarosite residues, and that several other steps of the wet circuit could be improved. 

Figure 11.4 Rotary vacuum drum filter (Courtesy of Filtration Services Lt4 Macclesfield, U.K.)...

Theory vs Practice Rotary Vacuum Drum Filter... 

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