Modified physical refining process

This process is based on the fact that a certain amount of soap is required for the hydrated silica to adsorb phospholipids from the oil. Since no caustic is used in physical refining process (Section 5.10), hydrated silica becomes ineffective in the physical process and does not remove any amount of phospholipids from the oil. In the modified physical refining process, the oil is analyzed for ppm of phosphorus. The required amount of caustic solution is added to the oil to produce soap. The concentration of soap produced (ppm) must match the ppm of phospholipids in the oil. The oil and caustic solution are mixed in a high shear mixer. Hydrated silica is added to the oil in a vacuum vessel. The remainder of the process is similar (bleaching, and so forth) to the physical refining process. 

Modified physical refining process also eliminates effluent discharge but removes more phosphorus and trace metals than the physical refining process. 

Both the modified chemical and modified physical refining processes were first introduced by the W. R. Grace Company, the inventor of the hydrated silica, Trysil. Other companies later introduced their versions of similar refining techniques. 

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There are two principal continuous refining processes physical refining and chemical refining. Three other continuous refining techniques used in the sunflower oil industry are improved modifications of the above processes. These include the cold chemical refining process, the modified chemical refining process and the modified physical refining process. 

Deodorization is the final step in the production of RBD oils and modified fats. The process is called deodorization if most of the FFA is removed by alkali neutralization as with row crop ( soft ) oils, and physical refining if,... 

Modified acid-degumming is a physical refining pretreatment that incorporates the benefits of caustic soda neutralization. This physical refining preparatory process treats the oil with a degumming acid and then partially neutralizes it with NaOH in solution. The amount of NaOH used is limited to prevent soap formation. The metal-phospholipid complexes are dissociated by the acid into insoluble metal salts and phospholipids in their acid form, which are still soluble in oil. The NaOH addition raises the pH and converts the phospholipids into sodium salts that are hydratable. The hydrated salts can be centrifuged for separation or dried to form agglomerates for adsorption on silica for removal with filtration. 

Various refined, modified or otherwise processed grades of commercial lecithin are available (e.g. fractionated, phosphorylated, acylaled, hydroxylated and hydrogenated), with consequent differences in composition and physical properties. Liquid, plastic or free-flowing forms can be made. Modified lecithins can function as both oil-in-water and water-in-oil emulsifiers. Hydrogenated varieties have reduced proportions of unsaturated carbon chains in the phospholipids, and are therefore more stable towards oxidation (Table 12.46). 

Usually, the ore or concentrate cannot be reduced to the metal in a single operation. An additional preparation process is needed to modify the physical or chemical properties of the raw material prior to its reduction. Furthermore, most pyrometaHurgical reductions do not yield a pure metal and an additional step, refining, is needed to achieve the chemical purity that is specified for the commercial use of the metal. 

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