A process for the reactivation of spent clay

摘要

Spent refining clays used in the refining of oils, fats and similar substances, are regenerated by treating with a non-acidic organic solvent in the presence of a vaporizable basic substance, and after removing the solvent, treating the clay with steam. The solvent and basic substance used do not form polymers under the treatment conditions, and preferably boil below 200 DEG C., whereby they are completely vaporized at the final steaming stage. The extraction may be effected by a single substance consisting of a vaporizable organic base. Suitable solvents are; primary and secondary alcohols, ketones, ethers, acetals, mono-nitro-derivatives of hydrocarbons, chlorinated hydrocarbons, or hydrocarbons. Examples; isopropyl, butyl, amyl, benzyl, or cyclohexyl alcohols, furfurol, acetaldehyde, acetone, methylpropyl ketone, diacetone, isopropylethyl ether, ethylene glycol ethers, nitro methane, naphtha, gasoline, xylene, chloroform, or carbon tetrachloride. Ketones of 4 to 7 carbon atoms and chloroform are preferred. Mixtures of polar and non-polar solvents may be used especially mixtures of solvents of high and low dipole moment, for example, mixtures of methyl alcohol or acetone and aromatic hydrocarbons or chlorinated hydrocarbons. Low dipole moment is defined as from 0 to 1.10-18 e.s.u. Vaporizable basic substances are; ammonia, amines, imines, alkanolamines, or hydrazines. Examples; ethyl-, or isopropylamine, ethylene diamine, aniline, mono-ethanolamine, methyl hydrazine, pyridine, quinoline, pyrrole, piperidine, piperazine or petroleum bases. Spent clay, such as bauxite or silica gel, containing oil enters a filter 2 through a line 1. Liquid is drawn off into a still 4, and the clay is first washed with naphtha admitted from a tank 5, then treated with steam and dried by a gas such as air or flue gas. The clay is then transferred to an extractor 13 where it is agitated with a non-acidic solvent admitted from a tank 28, together with the basic substance which may be admitted to the tank 28 or added directly through a line 33. This step may be effected under ordinary or super atmospheric pressure. After washing, the liquid is withdrawn through a line 14 into a tank 15 from which it passes to a still 24. Vapours are condensed at 17 and the condensate is pumped from a separator 19 to the tank 28. The extracted clay is freed from solvent by steam, the vapours being condensed and then freed from water in the separator 19. Steaming is continued, preferably under reduced pressure, until the issuing vapours are free from the basic substance. The steam may contain carbon dioxide, sulphur dioxide, sulphuretted hydrogen, or hydrochloric acid.