Clays filtration

Clay filtration is commonly used at airports and terminals to remove water, solids and unwanted compounds prior to use of the jet fuel. 

Clay filtration can be utilized to effectively remove polar compounds such as corrosion inhibitors, electrical conductivity improvers, and antioxidants from jet fuel. Also, more costly molecular sieve techniques can be utilized to remove contaminants from jet fuel. 

Clay filtration and molecular sieve filtration may remove enough of the higherboiling-point polar compounds from the jet fuel to improve WSIM. 

Clay filtration can be used to remove existent gum from fuel... 

Clay filtration will remove color bodies and high-molecular-weight compounds from fuel... 

A great many industrial products besides those mentioned in Sections 11.2 and 11.3 depend in some way on H bonds. For finished goods that require certain catalysts (hydrous metal oxides), color removal (by clay filtration), or flotation separation, adsorption influenced by H bonds is sometimes critical. Finally, some materials require H bonds to achieve or maintain their desired form or to cairry out their functions an example is the urea complexes used in separating paraffin hydrocarbons (110). 

The standard re-refining process uses sulfuric acid to dissolve sludge. The oil phase is further cleaned by clay filtration. The process is so inefficient that one-third of the oil is lost and disposal of the acid solution is increasingly difficult. 

The most common name is neutral (N) which was derived in the days when the lube distillates were acid treated (sulfuric acid) followed by clay filtration. After clay treating the oil was acid free or neutral. The viscosity number in this example, 150 N, is the approximate viscosity of the base stock (Note the ASTM viscosity classification refers to an industrial oil grade system, not the base stock viscosity system) expressed in Saybolt Seconds Universal (SSU) at 100 F. 

The ECLP tube press was originally developed for the filtration of china clay but has been used with many other slurries such as those in mining, Ti02, cement, sewage sludge, etc. The typical cycle time is about four minutes or more. 

Originally designed for the continuous filtration of conditioned sewage sludges, as were most of the filter belt presses available, the Manor Tower press is increa singly used for the treatment of paper mill sludge, coal, or flocculated clay slurries. 

Modem practice is to maintain the white water system as closed as possible, ie, as much water as is compatible with efficient machine operation is recycled. The loss of fibers and inert furnish components, particularly clay, has been gready reduced. Eiber losses, however, stiU occur into the white water, and greater economy of operation may be achieved if these fibers could be recovered. Thus, it is common to design a fiber-recovery system into the white water cycle. The three general types of save-all fiber recovery are based on filtration (qv), dotation (qv), and sedimentation (qv). If these are operated efficiendy, the net fiber loss can be less than 1%. 

Low Solids/Nondispersed. Fresh water, clay, and polymers for viscosity enhancement and filtration control make up low sohd/nondispersed muds. Low soflds muds are maintained using minimal amounts of clay and require removal of all but modest quantities of drill soflds. These are called nondispersed systems because no additives are used to further disperse or deflocculate the viscosity building clays. Most water-based muds are considered dispersed because deflocculating additives are used to control the flow properties. 

Hydrating bentonite in fresh water before adding it to the mud greatly increases its efficiency when the makeup water is contaminated with salt and/or hardness. Prehydrated bentonite can be protected from dehydration by flgnosulfonate (70) or sulfomethylated tannin when used in saturated salt water. Salt water clays, such as sepioflte and attapulgite, provide no filtration control and are normally used with suitable filtration control agents. 

Solids present in oil and synthetic muds must be kept wet with the nonaqueous phase to prevent coagulation and settling and mud instabiUty. Oil-wetting agents are normally incorporated in the basic mud package. These materials are typically amines or quaternary ammonium salts having hydrocarbon chains of 10 or more carbon atoms. They also render clays or lignites oil-wet for use in viscosity and filtration control (128). 

Many other polymerization processes have been patented, but only some of them appear to be developed or under development ia 1996. One large-scale process uses an acid montmorrillonite clay and acetic anhydride (209) another process uses strong perfiuorosulfonic acid reski catalysts (170,210). The polymerization product ia these processes is a poly(tetramethylene ether) with acetate end groups, which have to be removed by alkaline hydrolysis (211) or hydrogenolysis (212). If necessary, the product is then neutralized, eg, with phosphoric acid (213), and the salts removed by filtration. Instead of montmorrillonite clay, other acidic catalysts can be used, such as EuUer s earth or zeoHtes (214—216). 

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