Jigging

Figure A2.4.12 shows the two possibilities that can exist, m which the Galvani potential of the solution, (jig, lies between ( )(I) and ( )(n) and in which it lies below (or, equivalently, above) the Galvani potentials of the metals. It should be emphasized that figure A2.4.12 is highly schematic in reality the potential near the phase boundary in the solution changes initially linearly and then exponentially with distance away from the electrode surface, as we saw above. The other point is that we have assumed that (jig is a constant in the region between the two electrodes. This will only be true provided the two electrodes are iimnersed in the same solution and that no current is passing.

Another separation device that may be used is the mineral jig. This unit produces a loose vibrating bed of particles in a Hquid medium. The vibrations segregate the soHds into layers of density. The dense nonferrous metals, primarily lead, 2inc, and copper are at the bottom while organics are at the top. The middle layer is primarily glass. 

Gravity concentration, ie, the separation of ore from gangue based on the differences in specific gravities, using jigs, heavy—medium separators, or spiral concentrators for example, is appHcable for lead ores. However, the predominant beneficiation technique used in modem plants is the bubble or froth flotation (qv) process (4,5). 

Value given is per square meter of jig or table. Value is in meters. 

Fig. 11. Schematic diagrams of the basic types of jig where represents the jigging action (a) Denver/Har2 and (b) Batac. (c) Schmatic of a shaking table,...

Another factor is the increasing use of robots in mol ding shops. Large stmctures are removed hot from the mold by robots and clamped to a jig to cool, ensuring that no distortion or warpage takes place during the cooling cycle. 

Tocainide is rapidly and well absorbed from the GI tract and undergoes very fitde hepatic first-pass metabolism. Unlike lidocaine which is - 30% bioavailable, tocainide s availability approaches 100% of the administered dose. Eood delays absorption and decreases plasma levels but does not affect bio availability. Less than 10% of the dmg is bound to plasma proteins. Therapeutic plasma concentrations are 3—9 jig/mL. Toxic plasma levels are >10 fig/mL. Peak plasma concentrations are achieved in 0.5—2 h. About 30—40% of tocainide is metabolized in the fiver by deamination and glucuronidation to inactive metabolites. The metabolism is stereoselective and the steady-state plasma concentration of the (3)-(—) enantiomer is about four times that of the (R)-(+) enantiomer. About 50% of the tocainide dose is efirninated by the kidneys unchanged, and the rest is efirninated as metabolites. The elimination half-life of tocainide is about 15 h, and is prolonged in patients with renal disease (1,2,23). 

Scouring may be conducted on jigs, boil-off machines, or kettles, depending on fabric weight, constmction, and crease tendency ia the rope form. A combination of a synthetic detergent and soda ash is usually used and scouring is conducted at 85—100°C. Certain nylon blends may require less stringent conditions and the use of less alkaline builders, such as tetrasodium pyrophosphate. 

Cellulose Diacetate. When preparing cellulose diacetate for dyeing, strong alkahes must be avoided in the scouring of acetate because the surface of the cellulose acetate would be saponified by such treatment. Many fabrics tend to crease and therefore requke open-width handling. Scouring is frequendy carried out on a jig or beam using 1.0 g/L of surfactant and 0.5—1.0 g/L tetrasodium pyrophosphate for 30 min at 70—80°C. 

Very small quantities of acetate staple are dyed, however, large quantities of acetate filament are found in satin, taffeta, and tricot fabrics these are usually dyed open-width on a jig owing to thek inclination to crease or crack easily. A typical dyeing procedure on the jig involves addition of acetic acid and dispersing agent over two ends at 50°C. The disperse dye is added over two ends and the dyebath temperature is gradually raised to 80°C in 5°C increments with two passes at each temperature. The dyeing is completed after 30—60 min at 80°C. 

Many improvements have been made to streamline performance and to reduce machine operation labor. Some of these are tensionless jigs using variable speed electric motors with built-in drag for brakes, automatic reversing equipment, and automatic temperature and level controls. These machines are widely used for goods that are easily creased, such as fabrics consisting of filament acetate, heavy filament nylon, or cotton duck. They are also convenient for small dye lots and for sampling purposes. 

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