Thermphos' Phosphoric acid is used in the manufacture of Biofuels, Edible Oil & Fat refining and Sugar refining.
Vegetable oils are obtained either as crops from a tree, e.g. olive oil, palmnut oil or coconut oil, or from the seed of annual crops, such as rape seed oil or sunflower oil. Before the oil can be used commercially it must be extracted and refined. The extraction is carried out first. The resultant crude oil is now ready for refining.
Refining
Refining transforms the crude oil into a usable material for industry. Crude oils contain a number of minor components that can affect the acceptability of the product. Primarily, these are fatty acids, phosphatides, pigments and volatile components. The refining must also remove compounds introduced into the product during the process itself, e.g. soap produced during the fatty acid removal stage.
Degumming
Degumming is the process of removing phosphatides, such as lecithin, from the oil. Some of these are readily hydrated and can be removed by precipitation in water. Others, mainly the calcium and magnesium salts of phosphatidic or lysophosphatidic acids, can be hydrated by alkali or acid. The gum, when separated, can be further processed to produce lecithin.
Phosphoric acid can be used in two forms of refining: - base cleaning, and mechanical cleaning.
With both methods it is usually necessary to further refine the effluent, by reintroducing it into the process at the solvent extraction stage. This is necessary because of the heavy carry-over of oil in the solids from the centrifuge.
Refining of Edible Oils
Edible oil refining utilises phosphoric acid in a purification process whereby the raw oil is heated to high temperature and mixed with 0.1% phosphoric acid. Unwanted gums, lecithins etc. are coagulated and separated off. The application is assuming more importance since modern extraction methods employ solvent extraction techniques which produce a cruder product requiring larger additions of phosphoric acid in the purification stage.
Sugar Refining
Phosphoric acid and lime are used in the refining of fresh cane or beet sugar juice. This phosphate-lime process is known as clarification or defecation. This involves removal of solubles and fine suspended matter in order to give a clear solution which will filter easily. A second purpose is to remove any colloids, gums, pectins, albumin and colouring matter. Addition of lime and phosphoric acid to the raw juice results in a flocculant precipitate of calcium phosphate which slowly floats to the surface carrying the impurities with it and is skimmed off. The residual liquor, now much cleaner and easier to filter, is then given a polishing filtration.
Read more about the use of Phosphoric acid in these applications further in this website.