Bentonite filtration

Solids can be classified as those required for drilling and those detrimental to the drilling operation. Required solids are viscosifers (bentonite), filtration control agents, and weighting materials (barite). Viscosifers and filtration control agents are usually colloidal in size, i.e., smaller than 2 pm—Table 4-56 [29]. 

Figure 14.3 Temporal changes in fouling deposition for 200mgr bentonite filtration CFV of 15 + 0.2mm s flux of 75 I m h ). The hollow fibre membrane is visible as the dark area below the white line. He and Hfe indicate stagnant cake height and fluidised cake height, respectively.

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. 

Seawater muds are composed of bentonite, thinner (lignosulfonate or lignosulfonate and lignite), and an organic filtration control agent. The typical formulation of a seawater mud is 3.5 Ib/bbl of alkali (2 Ib/bbl caustic soda and 1.5 Ib/bbl lime), 8 to 12 Ib/bbl of lignosulfonate, and 2 to 4 Ib/bbl of bentonite to maintain viscosity and filtration. Another approach is to use bentonite/thinner (ligno-sulfonate)/freshwater premix, and mix it with seawater that has been treated for hardness. This technique will be discussed in the saturated saltwater muds section. 

A modified saturated saltwater mud is prepared with bentonite clay by a special technique. First, bentonite is hydrated in freshwater, then treated with lignosulfonate and caustic soda. This premix is then mixed with saltwater (one-part premix to three-part saltwater). The mixture builds up a satisfactory viscosity and develops filtration control. Thinning of the mud is accomplished by saltwater dilutions additional premix is required for viscosity and water loss control. 

For low solids muds with bentonite extenders the API filtration rate is approximately twice that which would be obtained using a conventional clay/ water mud having the same apparent viscosity. 

Examples of filtration control additives are latex, bentonite with a dispersant and other various organic compounds and polymers. 

Seawater muds are composed of bentonite, thinner (lignosulfonate or ligno-sulfonate with lignite), and an organic filtration control agent. 

However, the mechanism of action of filtration control additives is not yet completely understood. Examples are bentonite, latex, various organic polymers, and copolymers. Many additives for fluid loss are water-soluble polymers. Vinyl sulfonate fluid loss additives based on the 2-acrylamido-2-methyl-propane sulfonic acid (AMPS) monomer are in common use in field cementing operations [363]. The copolymerization of AMPS with conjugate monomers yields a fluid loss agent whose properties include minimal retardation, salt tolerance, high efficiency, thermal stability, and excellent solids support. 

The application of ion exchangers to dextrose process liquors involved considerable experimental work because of a number of factors which do not enter into their application to water purification. The accumulation of fats and proteins on the resin surfaces must be guarded against by proper clarification of the liquors to be treated. Such accumulation may result from precipitation as the neutralization progresses, and may soon destroy the effective acid-removing capacity of the anion exchange resin. This difficulty can effectively be eliminated by prior precipitation of thfe refinery residue from the acid liquor by bentonite, a colloidal clay of opposite electrical charge to the colloids,21 followed by filtration. 

The fats and proteins are coagulated by treatment of the hydrolyzate with a small quantity of bentonite. The coagulated residue is filtered from the hydrolyzate with the addition, if desired, of a small quantity of filtered to improve the filtration rate. The hydrolyzate must be properly clarified in order to reduce to a minimum the potential contamination of the ion exchange resin with extraneous material. 

Supercritical drying (SCD) The wet cake of sol pillared bentonite (sol-PILB) was dispersed into absolute ethanol and filtrated, washed with ethanol for several times to replace the water by ethanol. The cake was transferred to a cartridge and the ethanol was extracted by supercritical fluid (CO2) for 3 h under 3000 psi, at 323 K. The flow rate was controlled around 2.5 ml/min. The sample was then calcined at 773 K for 12 h and labeled as sample SCD. 

A portion of the wet sol-intercalated clay was mixed with a surfactant of quaternary ammonium salts [CH3(CH2)n-i N(CH3)3Br] by stirring for 2 hours. 15.75 mmol of surfactant was added to each gram of the starting bentonite clay. The resultant mixture of clay and surfactant was transferred into an autoclave and kept in an oven at 100°C for 3 days. The wet cake was washed with water to Cl ions free and the solid was recovered by filtration. The solid was dried in room temperature and calcined at 773 K. for 4 h. The calcined products were labeled as sol-PILB-Cn, where n denotes the number of carbon atoms in the alkyl chain of the surfactants used. Four samples were prepared sol-PILB-C12, -C14, -C16 and -C18. 

In a screw-capped vial were placed malonic acid (0.52 g, 5.0 mmol, 3 equiv.), p-tolualdehyde lc (0.20 g, 1.67 mmol) and bentonite (0.72 g). The tube was capped and the contents of the tube were thoroughly mixed with a vortex mixer and then irradiated in the microwave oven for 5 min at a power of 1050 W. After the reaction the mixture was cooled to room temperature and washed successively with hexane (3xl0mL) and cold water (3xl0mL). The resulting mixture was immersed in ethyl acetate (2x10 mL) for 5 min. After removal of bentonite by filtration under vacuum, the mixture was evaporated under reduced pressure to give 2-(4-methylbenzylidene)malonic acid 2c as a white solid (0.29 g, 86%). This solid was recrystallized from hot, distilled water, mp 205-208 °C. 

Smiles, D.E., Kirby, J.M., and Little, I.P. (1996) Hydrodynamic dispersion and chemical reaction in sodium bentonite during filtration in the presence of calcium sulphate. Chem. Engng Sci. 51, 3647-3655... 

Wear eye protection, butyl rubber gloves,10 and laboratory coat. Cover spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand.11 Scoop the solid into a container, transport to the fume hood, and slowly add to water allowing 20 mL of water for each 1 g of hydrazine. Remove the clay and sand by filtration. For each 1 g of hydrazine, place 120 mL (about 25% excess) of household laundry bleach (containing 5.25% sodium hypochlorite) into a three-necked, round-bottom flask equipped with a stirrer, thermometer, and dropping funnel. Add the aqueous hydrazine dropwise to the stirred hypochlorite solution at such a rate that the temperature is maintained at 45-50°C. The addition takes about 1 hour. Stirring is continued overnight (at least 12 hours). The reaction mixture can be flushed down the drain with at least 50 times its volume of water.12 13... 

Wear breathing apparatus, eye protection, laboratory coat, and butyl rubber gloves. Cover spill with 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand.8 For each 1 mL of iron pentacarbonyl, place 45-50 mL of household bleach (about 5% sodium hypochlorite solution) in a plastic bucket equipped with a stirrer and located in a fume hood. Dilute the bleach with three times its volume of water and, to this solution, slowly add the contaminated spill mix while stirring. Continue the stirring for a period of 48 hours, and then filter the slurry using vacuum filtration. The... 

Refrigeration. At least one major winery minimizes the amount of wine movement necessary by cold stabilizing the wine at 28° F (-2.22° C) in a jacketed tank until laboratory evaluation shows the wine to be cold stable. The wine is allowed to warm to 30°-32° F (-1. ll°-0° C), then a slurry of bentonite, which has been soaked at least overnight in hot water, is added to the wine at the level prescribed by the previously described laboratory procedure. When the bentonite has settled to the bottom of the tank, the wine is racked off the bentonite lees and filtered to a holding tank. The wine is now ready for polish filtration and bottling. 

The new wine usually is fined, or more tightly centrifuged, or given a preliminary filtration, around the first of the year. Bentonite is used most commonly, the amount being determined by laboratory-size samples of different concentrations. The average quantity is about 0.3 mg/L. The proprietary material Sparkalloid also is used a great deal, as is the classic... 

Vinegar clarification is accomplished by filtration, usually with the use of filter aids such as diatomaceous earth or bentonite. After clarification, vinegar is bottled, sealed tightly,... 

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