DE1719461B2 - METHOD FOR PURIFYING INORGANIC OR RAW ORGANIC PRODUCTS - Google Patents

Description

dissolved in a solvent, then by evaporation or cooling crystallization as an intermediate product crystallized from the solvent and separated from the mother liquor.

During the crystallization of inorganic or organic substances from technical solutions, the Residual solution as a result of the concentration due to the failure of the crystals and, during the evaporation

resulting residual solution either directly to the solution container to dissolve the crude product or
partly again to the intermediate product in the mash tun, partly directly to the solution tank for 20 Apart from this, the raw product is fed in an economical way of dissolving. Performed technical procedures for such a ver

speed level is only available for a limited period of time, which is too small for a sufficient effect of such a washing process. Aub H. Lux, Inorganic Chemical Experiments

tierkunst, 1959, pp. 241 and 242, is the washing of

Filter cake on a laboratory suction filter known, it may be useful to put the substance in the suction filter after interrupting the suction with something

The invention relates to a method for cleaning 30 or to stir washing liquid into a paste Inorganic or organic raw products that can be rubbed in even in a bowl. It is here a laboratory technique, but not an economically feasible one on an industrial scale Process for the purification of inorganic or organic raw products. The same applies to the literature reference W e y g a η d, organic-chemical experimental art, 1948, p. 92, in which collecting and washing out is described by crystals. Again, it is suggested to use the material under certain

development or cooling crystallization, as a result of the withdrawal 40 circumstances in the mortar with washing liquid Acquire a more or less large amount of the solution, work through it well, and then start over again by means of mostly relatively highly concentrated dissolved solids on the filter to wash out. Disadvantageous Impurities. This dissolved impurities is in such an applied technique that are based on a crystallized finished product after the crystals have been separated off Residual solution via filter or by means of centrifuges in 45, which is carried out on the filter with a final wash the moisture content of the solid crystallizate product is subjected to a suitable washing liquid, th and remain as impurities in the product obtained after the moisture has dried off.

It is known to wash these dissolved impurities on the centrifuge or on the filter to be removed as far as possible with a pure solvent or with another liquid substance. It is true that that which can be achieved by such a wash is sufficient

The quality of the product can in many cases be disadvantageous without the need for technically complex measures, however, or for the reprocessing and loss of the washing liquid. In addition, are
Many cases are known in which higher quality demands are made than would be made by simple
Crystallization and subsequent washing on the 60
Separator can achieve. It is known that this disadvantage can be eliminated by redissolving the crystalline product in pure solvent
and subjected to recrystallization.

Apart from the fact that this was again used undesirably and that the residual solution obtained from the mash after separation of the pure consumed large amounts of solvent and crystallizate then discarded or worked up either directly to the solution container to dissolve the must, is the requirement of repeated crystal crude product or partly again the intermediate product

the washing liquid being discarded in any case. In the case of easily soluble products leads this leads to high product losses.

The invention is based on the object of creating a method with which an improved cleaning a product obtained in a first crystallization stage, i.e. one from a crude product produced intermediate

appropriately large amounts of solvent must be used and without additional thermal energy is needed.

The object is achieved according to the invention in that one for the dissolution of the crystalline crude product Required amount of pure solvent for mashing the crystalline before recrystallization Intermediate product without external heat

3 4

Mash tun partly directly to the solution container For example, embodiments of the invention

Ü "Dissolving the crude product is supplied. Appropriate procedures are indicated in the drawing

"" ■ The separation of the residual solution from is illustrated. It shows

Hen crystals are made in a centrifuge. F i «1 is a flow diagram for the purification of from In the inventive method is, corresponds 5 ^ ßriger solution recovered oxalic acid, wherein in peeen the previously known cleaning methods on _F j _{u ia the} operation of the present invention which repeated ine, heat energy and solvent _Fi ~ _{lb for} v _erg i _e idi illustrated recent consuming crystallization and / or a long operation is juxtaposed dispensed-drawn-washing process and siatt whose Fi "2 purification of simple from an aqueous solution Tine cold cleaning with a small amount io _{ABG '. Scnic} d _A citric acid, made schematically as a flow of pure solvent. The _{product obtained according} to the invention in this case bUd where in ρ i g. 2a nevertheless has a considerably higher _{quality than that illustrated in F} ·, _{e 2} b for comparison; one can see the percentage Salary is _{compared to known} working methods.

^V SSSKni ⁿ «r« SSl ₁ ^{ProdUkt Um} ., Identical parts are given the same reference numbers.

■ - "■ ^Procedure Γ ¹ ""' ^allEe " ^Se Da's in F i g. 1 illustrated flow scheme illu-

_{llsl WI1U} ^ . ".." The crude product prevents the purification of an acid contaminated

■ -hlidier and known queens wöbe a suitable purified aqueous oxalic acid, i.e. crude acid

? Sunscreens, for example water or an or- 20, had the following composition:

Anic solvent, dissolved and obtained from the Gcwichisanicile

That solution crystallized out as an intermediate product. Oxalic acid 2 H2O ^{9l) 9}

n _as crystallization is also known as H-SOj

by indirect cooling from the outside or by ^ ₀ '' 74

Evaporation or evaporation cooling carried out * 5 · ■ ■ _{] () () ()} then taken. B. in ™ «£ ^ &<™ ^ l ™ l ~ r I" ™ '^ containers 1 were replaced by a Zi · ™' -

in

Recovery »,,! ^„ R _e ea, i, c _M1 3. <^ ™ Sj. ^

the RoI, -

in

ή "« · "Stirrer glass, without a hot mixer

It is advisable to have the temperature that corresponds to the final residual solution at dc dmA d «e Leig ^

temperature of the crystalline product before disposal was ^ and net., ^ as * r ^ g _16n . _{The crystalline}

Heren from the mother liquor If one, m 40 16 .kg of sweat sau ^ ^^ ^ _

Stirred vessel the crystalline intermediate product with P ™ daU das mune «JJ _{and received ncbcn}

"" The mash is subsequently extracted from the residual solution, for example in a centrifuge. The crystals separated from the knead in this way are obtained with a considerably increased purity, e.g. B. discharged from the centrifuge p, e residual solution. the product to be cleaned in the concentration concentration next to the impurities. _S is advantageously contains Ungen either the mother liquor from the crystallization step or with the Au d.eser losevorgane or supplied to the dissolution process directly. ⁸ The process according to the invention let S.Di both from water recovered as Lösungsm.tte knsta 1-line products as well as for other Knstallprodukte worckn are deposited, for example, from organic -7 ^ 'or Lösungsmittelgemiächen apply. It is eminently suitable. To purify products such as adpic acid, fumaric acid, maemic acid, oxa acid, citric acid, dimethyl terephthalate, dicarboxylic acid and various other substances for which one has to require a purity of _{i, nh P.}

light _{up the} procedure is the du-ch

Bcjr ^ ^r « ⁱⁿ J ^u ^ _{cr Zen} trifuge 5 withdrawn Oxal-J" order » _{Ab I 6} introduced, the

saua η em _{t mQ kg an k} , _

duuh . <. me Len y ^ ^^ _h .

™ ^kt _e ^ _e feed line 14 342 kg of water were added over by e ^ . Of the

J equipped with a stirrer

lter ^ ^. ^ _{prod kt wur} .

£ ^ ₁₁ without temperature increase, be, Z.mmerd ^ ^ e uniformly mixed and

u .mpc J ^ " ¹ '^ _{through the line} 11 of the gc- ^ n ^ enc crystal pulp fed to a centrifuge 10 ° d you separated crystals from the residual solution'" ^{the 0} J _{1948 k of} crystal pulp were 1092 kg J ^ _un g ' _{and 856} k _S of purified crystals ge ^ ^ ^u ^ _ie ^UI _residual soluble contained 1011 kg J na in addition to water. ui b sulfuric acid while the

On. »Ure and ^ ^ _{oxalic acid} . _Dlhydra t

re.n.gio

0.070 kg of sulfuric acid had what, based on dry oxalic acid, an impurity of only Corresponds to 0.0087% H2SO4. The residual solution was via the return line 12 together with the 342 kg of water from line 14 are returned to the supply line 3.

In Fig. 2, the purification of an aqueous, with Illustrates sulfuric acid contaminated citric acid. In the case of the FIG. 2a illustrated work process 1000 kg of raw citric acid were introduced into the dissolving container through the feed line 2, had the following composition:

940 kg citric acid H2O

(about 860 kg citric acid and 80 kg H2O)

60 kg of moisture

(with 36 kg citric acid,

23 kg H2O and 1 kg H2SO4)

Through the supply line 3, 693 kg of the residual solution were transferred from the return line 12 into the dissolving tank introduced, had the following composition:

423 kg of citric acid
0.083 kg sulfuric acid
Rest water.

In the dissolving tank 1, the mixture to 60 ^c C was heated and placed under stirring until dissolved, after which it was transferred to the crystallizer 4 and is cooled to 25 ° C. The resulting crystalline product was transferred together with the mother liquor to the centrifuge 5, from which 693 kg of mother liquor with 423 kg of citric acid and 0.9965 kg of sulfuric acid were drawn off through line 7. 1000 kg of crystalline product were discharged through the discharge 8 which, in addition to 940 kg of citric acid · H2O, contained 0.0865 kg of sulfuric acid.

This crystalline product was transferred into the mash tun 6, into the 218 kg through line 9 Water and residual liquid from the return line 12 through line 13 were introduced. At room temperature was mashed into a slurry, and then the slurry was placed in the centrifuge 10, in which he was converted into 525 kg of pure citric acid and 693 kg of residual solution was separated. The remaining solution, which is partly in the mash tun 6 and 7UI11 larger part through the return line 12 was circulated in the dissolving container 1. contained 423 kg citric acid and 0.083 kg sulfuric acid, while the pure citric acid product obtained from 495 kg citric acid ■ H2O (approx. 455 kg Citric acid) and 30 kg of moisture with 0.0035 kg of sulfuric acid, which, based on dry citric acid, corresponds to an impurity of as little as 0.0007 "/" H: SO4.

In comparison, FIG. 2b the processing of 1000 kg of raw citric acid of the same composition as in Example 2a with the same amount of water, but according to the previously known Working method, illustrated.

The 218 kg of water are transferred through the line 3 to the dissolving container 1 and through the supply line 2 the raw acid used has been introduced, supplied. It is made by stirring and heating a solution obtained at 60.degree. C., which is transferred to the crystallizer 4 and cooled to 25.degree. C. therein will. The product that crystallized out in the crystallizer was then mixed with the mother liquor introduced into the centrifuge 5 and separated therein. 525 kg of crystalline citric acid product fell which had the following composition:

495 kg citric acid H2O
(about 455 kg citric acid)

30 kg of moisture

(12 kg H2O and IS kg citric acid with
0.04fkg sulfuric acid);

In relation to dry citric acid, this means an impurity of 0.083 ° / n H2SO4.

The mother liquor was obtained in an amount of 693 kg from the centrifuge and contained water as well as water 423 kg citric acid and 0.959 kg sulfuric acid.

The above figures make it clear that the process according to the invention is successful to obtain crystalline products in a purity increased by a power of ten and more without additional thermal energy and excessive amounts of solvent and / or washing liquid are required.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Process for the purification of inorganic or organic raw products in a solvent dissolved, then as an intermediate product by evaporation or cooling crystallization crystallized out of the solvent and separated from the mother liquor, thereby ! isation with the aim of obtaining products of higher purity is disadvantageous. In such procedures the repeated Recrystallization depends largely on the purity of the final product that is finally obtained from how strong the impurities in the crystals are for the purpose of repeated crystallization is dissolved again. The repeated crystallization has apart from the relatively high consumption of solvents and thermal energy characterized that a disadvantage for the up 10 that the yield drops sharply. See Gail solution at elevated temperature of the crystalline t e r m a η η> »D! e Praxis d. org <-hem. ", 19o2. This disadvantage can also not be avoided by repeating it Avoid or reduce washing processes instead of recrystallization, because the washing of the Crude product before recrystallization required amount of pure solvent for mashing the crystalline intermediate product without
external heat supply is used and that after 15 stallisats can only be carried out up to a partial cleaning separation of the pure crystal from the mash, because the washing process is thereby carried out is limited that only a limited amount of scrubbing liquid can be used in order to to avoid loss of product through dissolution.