Slurry Classifiers

Heat Exchangers Using Non-Newtonian Fluids. Most fluids used in the chemical, pharmaceutical, food, and biomedical industries can be classified as non-Newtonian, ie, the viscosity varies with shear rate at a given temperature. In contrast, Newtonian fluids such as water, air, and glycerin have constant viscosities at a given temperature. Examples of non-Newtonian fluids include molten polymer, aqueous polymer solutions, slurries, coal—water mixture, tomato ketchup, soup, mayonnaise, purees, suspension of small particles, blood, etc. Because non-Newtonian fluids ate nonlinear in nature, these ate seldom amenable to analysis by classical mathematical techniques. 

After acid removal, scrap batteries are fed to a hammer mill in which they are ground to <5 cm particles. The ground components are fed to a conveyor and passed by a magnet to remove undesirable contamination. The lead scrap is then classified on a wet screen through which fine particles of lead sulfate and lead oxide pass, and the large oversize soHd particles are passed on to a hydrodynamic separator. The fine particles are settled to a thick slurry and the clarified washwater recirculated to the wet screen. 

Insofar as they are used to purify other products, several processes used in the refinery fall under the classification of dewaxing processes however, such processes must also be classified as wax production processes (2). Most commercial dewaxing processes utilize solvent dilution, chilling to crystallize the wax, and filtration (28). The MEK process (methyl ethyl ketone—toluene solvent) is widely used. Wax crystals are formed by chilling through the walls of scraped surface chillers, and wax is separated from the resultant wax—oil—solvent slurry by using fliUy enclosed rotary vacuum filters. 

Cla.ssifica.tion. Slurry leaving precipitation is classified into a coarse and one or more fine fractions, usually by elutriation in hydroclassifiers. Cyclones and combinations of hydroclassifiers and cyclones are gaining popularity. In smelting grade alurnina plants, the coarse fraction, called primary product, is sent to calcination the fine fractions, called secondary and tertiary seed, are recycled to be grown to product size. 

Addition of NaCl decreases the solubiHty of Ca(OCl)2 in equiHbrium with the dibasic salt and lime. The dibasic slurry is sent to a classifier. Finely suspended lime impurities are removed from the overheads yielding a clear Hquor, which is recycled to the lime slurry makeup. The bottoms from the classifier are chlorinated giving a slurry of Ca(OCl)2 2H20, which is centrifuged. The cake is mixed with strong, low salt NaOCl solution in a pug mill and... 

Several modifications of the preparation of neutral Ca(OCl)2 2H20 do not involve intermediates. In a continuous process, lime slurry containing caustic and Ca(OCl)2 mother Hquor is chlorinated under reduced pressure to remove the heat of reaction, and the resulting slurry is separated in a classifier into Ca(OCl)2— and NaCl-rich regions from which slurry is withdrawn to obtain Ca(OCl)2 filter cake and soHd salt (204). 

In another cocrystalHzation process, lime is mixed with 50% caustic and recycled filtrate and chlorinated to yield a slurry of calcium hypochlorite dihydrate and NaCl crystals that are separated in a hydrauHc classifier. The underflow is mixed with centrate mother Hquor and sent to a wet screen classifier the overflow is recycled to the hydroclone and the salt-rich bottoms are centrifuged. The centrate is recycled to the chlorinator and the salt used as feed to chloralkaH ceUs. The Ca(OCl)2-rich overheads from the hydroclone are centrifuged, the cake going to a dryer and the filtrate sent to the wet screen classifier (207). 

The termination of the cone section is the apex orifice. The critical dimension is the inside diameter at the discharge point. The size of this orifice is determined by the application involved and must be large enough to permit the solids that have been classified to underflow to exit the cyclone without plugging. The normal minimum orifice size would be 10% of the cyclone diameter and can be as large as 35%. Below the apex is normally a splash skirt to help contain the underflow slurry in the case of a hydroclone. 

Improved grinding media and linings, roller mills, high-efficiency classifiers, wet process slurry Dewatering with filter presses... 

A common problem in both chemical and metallurgical practice is that of separating relatively coarse particles, which are called sands, from a slurry of fine particles, which are called slimes. The most common method is to use continuous settling equipment called classifiers. 

Continuous vacuum filters are mostly of the constant pressure type and are mainly used in dewatering concentrated slurries such as concentrates. These filters are classified into disk, drum, and horizontal filters. The drum and the disk filters are the mainstay for most final detwatering, the drum filters being used to a lesser extent than the disk filters. These two groups of filters remove most fine particles from a process stream. 

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