Treating processes percolation

Thermofor continuous percolation a continuous clay treating process to stabilize and decolorize lubricants or waxes. 

Paraffin, Synthetic, occurs as a white wax that is very hard at room temperature. It is synthesized by the Fischer-Tropsch process from carbon monoxide and hydrogen, which are cata-lytically converted to a mixture of paraffin hydrocarbons the lower-molecular-weight fractions are removed by distillation, and the residue is hydrogenated and further treated by percolation through activated charcoal. It is soluble in hot hydrocarbon solvents. 

Centrifuging. Although the centrifuge process (Fig. 12-3) was the exclusive means of dewaxing bright stock for many years, it" is rapidly being displaced by solvent processes. Percolated or acid-treated and... 

Obviously to remove large amounts of asphaltic materials, substantial quantities of clay would be required in both the percolation and hot contacting methods, and the adsorption process then may become uneconomical in the treating of raw residua. With the exception of residual oils containing low concentrations of asphalts, oils to be treated with clay generally receive some pretreatment—for example, with sulfuric acid followed by neutralization of the acid oil, or selective solvent extraction. 

Waste water treatment. Supercritical CO2 has been put to use in a variety of industrial waste treatment applications. Clean Harbors Environmental Services, Inc., has used SCCO2 in Baltimore since 1989 to treat wastewater from chemical and pharmaceutical manufacturers. In the process the wastewater is pumped into the top of a 32-ft-high, 2-ft-diameter column, while the CO2 is pumped in from the bottom and percolates up. As the CO2 trowels up it dissolves the organics. CO2 contaminated with organics is at the top of the column, and clean water is at the bottom. The contaminants are incinerated off-site after separation from the CO2 which is recycled. 

We now consider application of percolation theory to describing mercury intrusion into porous solids. First we briefly recall the main physical principles of mercury porosimetry (in particular, the Washburn equation). These principles are treated in detail in many textbooks [e.g., Lowell and Shields 49)]. The following discussions (Sections IV,B and IV,C) introduce general equations describing mercury penetration and demonstrate the effect of various factors characterizing the pore structure on this process. Mercury extrusion from porous solids is briefly discussed in Section IV,D. 

The process developed by Gupta (19-22) processed crude oils with a combination of UF membrane separation and silica gel column percolation. The soybean and rapeseed-hexane miscellas were passed through various UF membranes. The solvent was removed from the permeate, and the degummed oil was then treated with bleaching clay, silica, and/or acid and finally was steam deodorized to produce refined, bleached, and deodorized oil. The color readings of the oils obtained... 

Metallurgical Practice.— Leaching of sands by percolation was very widely used in the United States up to a few years ago in the cyanide treatment of gold ores, and is still largely used in the Transvaal. The reason for its decline was the successful development of processes for the treatment of slimes at lower costs which resulted in the plants treating all their material as slime instead of separate treatments as before for sands and slimes. The question of removing the leached material from the tanks is handled in a number of different ways. 

Oleoresin of Cubebs. Moderately press 12 troy ounces cubebs in fine powder into a cylindrical percolator, and treat by the some process as the capsicum in the last formula. ( U. S, Ph),... 

L/D ratio See screw length-to-diameter ratio, leach To extract a soluble component from a mixture by the process of percolation. See percolation, leachate A contaminated liquid that drains from landfills and must be treated before entering the environment. It can contain decomposed wastes, decomposition byproducts, heavy metals, or bacteria. See geomembrane, lead 1. The distance in an axial direction from the center of an element such as a screw flight at its outside diameter to the center of the same flight. See directional property. 2. A heavy metal, Pb is hazardous to one s health if inhaled or swallowed. Its use is restricted. In plastics it is found in certain products, such as additives. Pb can be used in safe environments since it has excellent performance properties, such as resisting attack by many corrosive chemicals and is impervious to x-ray and gamma radiation. See hazard x-ray. 

---