DE605736C - Process for the complete revitalization of exhausted bleaching earth - Google Patents

Description

Process for the complete revitalization of exhausted fuller's earth The invention relates to a process for the revitalization of the bleaching of Bleaching earth used for oils, fats and the like. Fuller's earths are of their chemical nature after mostly magnesium silicates and magnesium aluminum silicates, often with additives of active coal. When such bleaching earths are exhausted after prolonged use, they contain both the dyes, mucilages and other substances removed from the 01 Impurities as well as a considerable residue of the treated oil. The revitalization of bleaching earth has so far encountered difficulties because the oil contained therein has an effect of any reagents on the contaminants made difficult or impossible. Also by glow was a complete resuscitation not to be achieved, as the incombustible impurities are difficult to achieve due to the glow become soluble and since the organic substances in the bleaching earth are in the finest Pores deposit small amounts of carbon, which clogs some of these pores and the effectiveness of the bleaching earth is reduced.

It has also been suggested to pass through the exhausted fuller's earth Extraction with volatile solvents such as gasoline, blenzene, carbon disulfide, Carbon tetrachloride, etc., to be lead-free from all oils and fats. The extraction takes place in the blekannen extraction devices and is driven until the bleaching earth is completely free of these oily impurities.

The oils and the like extracted in this way can after evaporation of the solvent can be recovered and, if necessary, further processed.

It has also been suggested both the oily and fatty Residues as well as the actual impurities (dyes, gums etc.) by treatment with dihydric alcohols or their derivatives, where appropriate an activation of the completely purified fuller's earth should close with acids.

All of these modes of operation are devoid of the present invention to do. According to the new process, the oil is de-oiled or degreased in the known manner Fuller's earth washed for at least t / 2 hour with aqueous alkali metal carbonate solution. In most cases, a 2% soda or potash solution is sufficient to which about 80 parts are mixed with 20 parts of the de-oiled fuller's earth.

Using soda or potash alone without washing it first Volatile solvents have already become known; however, one leads Such bleeding does not lead to a complete resuscitation of the exhausted Fuller's earth, because the salts mentioned alone never make the oily and greasy ones Components can be removed entirely. It turned out to be quite surprising shown that by the common Application only from volatile Solvents and then soda or pzottash solutions a practically complete one Revitalization of the bleaching earth can be achieved, which by the individual application The substances mentioned cannot be used instead of the alkali carbonate solutions aqueous hydrochloric acid can also be used for washing, e.g. B. an acid of about 20 % Hydrogen chloride content (d15 = 1.10).

The decision whether alkali carbonate solution or aqueous hydrochloric acid is to be used depends entirely on the type of contamination present. One will use soda or potash solution if made from water-insoluble acids Water-soluble salts can be formed or if protein-like bodies break down or if dyes are dissolved as a result. If, on the other hand, the fuller's earth is organic Bases or dyes that are soluble in acids, or if they are The removal of mineral impurities, such as lime and the like, is hydrochloric acid preferable. It has been shown that just hydrochloric acid in aqueous solution for the complete cleaning, d. H. for the removal of bases, dyes, etc., especially suitable is. The strong hydrochloric acid can after use in a distillation plant to be recovered.

Successive washing is also particularly useful with soda or potash solution and then with hydrochloric acid or first with hydrochloric acid and then with soda or potash solution. The washing itself is conveniently done in known way at boiling point, eatl. under pressure, but with a temperature of 110 ° should generally not be exceeded. In addition, it is necessary that Mixture of fuller's earth to stir vigorously with the solution, which z. B. in one blown out cylinder boilers or tanks made of acid-resistant stoneware can be done, which can be closed in a gastight manner and are provided with a stirrer and heating coils.

The paste of fuller's earth and solution is then dewatered by pressing, z. B. Mitteils frame filter press, and washed with water until the Wash water is completely pure and clear. flarauf, takes place in a known manner Drying in a drying drum; this may be followed by another Screening and air sifting.

In this way, the exhausted bleaching earth is completely restored to regenerate, so that it is as effective as freshness again.

If the fuller's earth contains active charcoal, after de-oiling, Wash out and dry, and anneal in the absence of air required, and about cherry red glow to light red glow. The duration of the annealing process is to be measured at least at 1 hour. This treatment results in a complete Revitalization of the symbolic earth as well as the active charcoal mixed with it.

D o u s e p o rt for cleaning soybean oil a bleaching earth mixture was used, which was 90% bleaching earth and 10% more active Coal existed. After use, this bleaching earth mixture had a fine gain in weight experienced from 30 to 50 0/0. This is used to revive the exhausted fuller's earth first extracted with gasoline and then, after removal of the gasoline, in dry State passed through a sieve of 3 mesh size into a mixing cylinder, where a treatment with 2% soda solution (4 parts by weight of solution to 1 part by weight Bleaching earth mixture) at 100 to 110 ° l. The duration of this treatment is at least half an hour. By boiling with the alkali carbonate solution, the ingested Impurities dissolved and the organic substances partially destroyed.

The boiled porridge is filtered off and so long with cold water washed until the filtrate is completely clear; the residue on the filter will then freed from most of the water by squeezing. From the used alkali carbonate solution If you stand for a long time, a small amount of active charcoal is deposited, which is collected can be used again for many purposes without further treatment is.

The bleaching earth mixture treated with alkali carbonate solution is thereafter in a completely drained and gas-tight lockable mixing cylinder, the equipped with a stirrer, heating coil and reflux condenser, for 1 hour with the 11/2 to twice the amount of hydrochloric acid (dt5 = 1.10, corresponding to 20.2 ° / 0 HC1) at 110 ° digested.

It is then cooled to the usual temperature and filtered through pressing at 10 to 12 12 atm. Overpressure removed.

The used hydrochloric acid is distilled back. The press cake out Bleaching earth mixtures are blown dry with cold water after they have been thoroughly washed, crushed and dried.

To make the activated charcoal contained in the fuller's earth fully ready for use again To do this, annealing under the exclusion of air is necessary. The temperature is about 8000 and must be maintained for about 1 hour.

The following is the discoloration power of the unused and of the revived Bleaching earth mixture shown, expressed by the Lovibond numbers soybean oil bleached with it. As a counterexample, there are also gives the Lovibond numbers of otherwise treated oil, one of them Times treated with fuller's earth, which is extracted only with gasoline and then with hydrochloric acid treated but not washed with Sloda solution, and treated the other time with fuller's earth, which was simply washed with potash solution and boiled.

I denotes the depth of color after treatment with a fresh one Mixture of fuller's earth and activated charcoal, the color depth after treatment with one after Revive Mixture and 3 the color depth according to the procedure described above Treatment with a similar revitalized mixture that extracts only with gasoline and then treated with hydrochloric acid, but not washed with soda solution and calcined 4 the depth of color after treatment with a similar mixture, but only that washed several times with potash solution and cleaned out.

L o v i b o n d counts B l e i c h -e r d e g e m i s c h e n g e b l e i c h t e n S o j a -öles yellow Red 1 .................... 12 0.89 2 12 0.89 3 I5 15 I, 35 4 ............ ......... 31 45 This shows that by the described in the embodiment Treating the exhausted fuller's earth has been fully revived while when using potash alone or when omitting the soda treatment and achieved a partially far lower effectiveness without subsequent annealing will.

The impurities absorbed when using the fuller's earth and Oil residues are completely removed again; also occurs with each resuscitation A weight loss of about 10% of the amount of fuller's earth originally used a.

Claims (3)

PATENT CLAIMS: I. Method for Complete Resuscitation of Exhausted Fuller's earth, characterized in that. the fuller's earth in a manner known per se degreased by extraction with volatile solvents and then in a known manner Way washed with soda or plotter solution at elevated temperature while stirring is, whereupon the mass is pressed, washed with water, dried and optionally is sieved and subjected to air separation. 2. Modification of the method according to claim 1, characterized in that that the treatment with soda or potash solution is a known lead action with hydrochloric acid is sent ahead or connected. 3. Procedure for complete resuscitation of those exhausted Fuller's earth, which has an active charcoal content, according to claims I and 2, characterized in that the mass after de-oiling, washing and drying is still being annealed.