Deflocculating additive

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. 

Wood Lignin AUcali-lignin, Lignosulphonate (from sulphite paper process) Clay deflocculant Additive in drilling fluids... 

Acryhc modifiers for cement impact strength and adhesion to substrates are discussed in reference 211. Both water-soluble acryhc and acryhc emulsion polymers are used in the ceramic industry as temporary binders, deflocculants, and additive components in ceramic bodies and glazes (212) (see Ceramcs). 

Organophosphoms compounds, primarily phosphonic acids, are used as sequestrants, scale inhibitors, deflocculants, or ion-control agents in oil wells, cooling-tower waters, and boiler-feed waters. Organophosphates are also used as plasticizers and flame retardants in plastics and elastomers, which accounted for 22% of PCl consumed. Phosphites, in conjunction with Hquid mixed metals, such as calcium—zinc and barium—cadmium heat stabilizers, function as antioxidants and stabilizer adjutants. In 1992, such phosphoms-based chemicals amounted to slightly more than 6% of all such plastic additives and represented 8500 t of phosphoms. Because PVC production is expected to increase, the use of phosphoms additive should increase 3% aimually through 1999. 

Forming additives or processing aids (2,33—37) are commonly used to render ceramic powders more processible. Binders and plasticizers (qv) are typically added to improve or aid dry powder and plastic forming, whereas deflocculants, surfactants (qv), and antifoams are commonly used in slurry processing. 

The hquid vehicle in a slurry should have a low vapor pressure for Hquid extraction and drying be compatible with the soHds and casting mold be inexpensive and be capable of dissolving and dispersing deflocculants and other additives. Distilled or deionized water is generally used as the Hquid vehicle, however, organic Hquids must be used for such moisture sensitive oxide powders as CaO and MgO, and for oxidation sensitive nonoxide powders, eg, AIN. 

Dispersed Noninhibited Systems. Drilling fluid systems typically used to drill the upper hole sections are described as dispersed noninhibited systems. They would typically be formulated with freshwater and can often derive many of their properties from dispersed drilled solids or bentonite. They would not normally be weighted to above 12 Ib/gal and the temperature limitation would be in the range of 176-194°F. The flow properties are controlled by a deflocculant, or thinner, and the fluid loss is controlled by the addition of bentonite and low viscosity CMC derivatives. 

Acid resistance is enhanced by fine milling and minimum clay additions to the slip. The setting agents (deflocculents) which hold the powder particles... 

By introducing surfactants, which lower the interfacial tension, it is possible to reduce the work necessary to deflocculate agglomerates. In liquid suspensions the introduction of an interfacial tension depressant facilitates wetting of the solid by the liquid and the displacement of adsorbed gases from the solid surface. Certain solids have adsorbed films whose adhesional forces are so great that they resist all mechanical efforts to displace them. Upon the addition of a surfactant, the Aims are displaced and a solid-liquid interface is achieved (1). 

Copolymers or terpolymers of acrylic acid, which contain from 5 to 50 mole-percent of sulfoethyl acrylamide, acrylamide and sulfoethyl acrylamide, ethyl acrylate and sulfoethyl acrylamide, acrylamide and sulfophenyl acrylamide, and acrylamide and sulfomethyl acrylamide, are claimed to be calcium-tolerant deflocculants for drilling fluids [704]. In general, 0.1 to 2 lb of polymer per barrel of drilling fluid is sufficient to prevent flocculation of the additives in the drilling fluid. 

What precautions could be taken to prevent the take up of impurities when reducing the particle size of zirconia from 10 pm to 1 pm Describe the beneficial effects that addition of a deflocculating agent might be expected to have on the ball-milling process. 

Although the production of highly deflocculated suspensions is a primary objective for formulation of suspension concentrates, these systems tend to settle under gravity forming dilatant sediments (clays). The latter must be prevented either by controlled flocculation or by the addition of a second disperse phase to the continuous medium (1). One method which may be applied to sterlcally stabilised dispersions, is to add a free (ie. non-adsorbing) polymer to the continuous medium. 

Silicates. The addition of sodium and potassium silicates to synthetic detergent has proved very beneficial. They have in solid or solution form important characteristics such as emulsification, buffering, deflocculation, and antiredeposition ability. 

In the literature, the reported use of zeta potential measurement for non-aqueous suspensions is relatively infrequent because non-aqueous suspensions only represent a small percentage of all medicated suspensions. Su and others evaluated the flocculation-deflocculation behavior of cefazolin sodium in non-aqueous media and the effect of surfactants as measured by zeta potential along with sedimentation and porosity measurements. A significant difference in zeta potential was observed when the particles were dispersed in peanut oil and ethyl oleate. The addition of lecithin reduced the zeta potential of cefazolin sodium, resulting in a deflocculated state accompanied by a decrease in sedimentation volume. The effect of surfactant... 

Rheological properties of casting slips are controlled by small additions of suitable electrolytes which promote deflocculation of aggregates and thus cause a decrease in yield point and increase in fluidity, which is desirable with respect to reduction of the required water content (refer to the section on slip casting). The stability of the suspension is also improved, i.e. the sedimentation of the solids is suppressed. 

Deflocculation, including its secondary effects, is a result of ion exchange on the surface of clay particles. The efficacy of this colloid-chemical adjustment is illustrated by the example reported by Norton (1952) addition of NaOH solution to mono-disperse fraction of H -kaolinite prepared by dialysis gives rise to an (approximately) 200-fold decrease in apparent viscosity, affected instantaneously in the region of pH 5-6, where complete exchange of ions for Na " has taken place. 

Additives serve a variety of functions in forming , which may be divided into four categories binders, plasticizers, dispersants (also referred to as deflocculants), and lubricants. 

Use Stabilization of asphalt emulsions, ceramic binder and deflocculant, dye leveler and dispersant, drilling-fluid additive, precipitation of proteins, extender for phenolic plastics, special molded products, source of vanillin, phenol, and of a component of battery expanders. 

If a natural clay is contaminated with soluble salts, they exert the crowding effect , the clay flocculates and the addition of deflocculants alone has little effect. Moreover certain anions, notably S04 ", are powerful flocculants. Fortunately in filterpressing most soluble impurities are removed, but some remain and have to be removed chemically. Calcium sulphate, CaS04 (in the foW of gypsum), is a common example of such a contaminant if present, the best way of removing it is to treat the clay with the requisite amount of barium carbonate, according to the equation ... 

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