DE726545C - Process for the production of potash from very dilute solutions, e.g. B. sea water - Google Patents

Description

Process for the recovery of potash from very dilute solutions, e.g. S. Meerwasser It is known that hexanitrodiphenylamine (dipikrylamine) has the property has, with z. B. calcium, sodium, magnesium, etc. readily soluble compounds too form, while the potassium compound is very sparingly soluble.

It has been suggested that this property of hexanitrodiphenylamine be used in analytical chemistry, and has also been proposed to exploit the same for the technical production of potash from very dilute solutions, e.g. B. sea water, to make usable, which contains potassium salts in addition to salts of metals, their compounds are easily soluble with Dipikrylamixi.

At. the technical production of potash using this process the very dilute solution a readily soluble di: picrylamine salt, z. B. calcium dipicryl laminate, added. The potassium salt is precipitated and can be filtered off. After that, will the potash salt with an acid; z. B. nitric acid, reacted, whereby the precipitation reagent is regenerated and can be used again. Excess of precipitation reagent is regenerated after the potassium salt is filtered off, namely by the fact that the Solution is made acidic enough, whereby free dipicrylamine is precipitated and be filtered off. can.

The present invention is based on the knowledge that the property of the hexanitrodiphenylamine mentioned above is for everyone highly nitrated, secondary, aromatic amines, in that with: highly nitrated « What is to be understood in this connection is that there are so many of the nitro compound in question That the compound contains nitro groups, as a compound sufficient for the formation of salts strong acid, occurs.

This is e.g. B. the case with penta- and hexanitrov compounds methylated diphenylamine, as well as with highly nitrated dinaphthylamine and phenylnaphthylamine as well as your homologue from their associations.

In contrast, tetranitrodiphenylamine is not acidic enough to make salts form. It cannot be determined in advance according to a general rule how the nitration must be driven high in order for the nitro compound to work becomes acidic enough, as this depends on which raw material nitrates will.

With regard to the solubility of the potash salt in question, it should be noted that that several of these compounds are cheaper than dipicrylamine. While thus potassium dipicryl laminate has a solubility of 0.62 per liter at 20 °, the potassium salt of hexanitramethyldiphenylamine has .a solubility of 0.46 g per liter and the potash salt of pentanitromethyldiphenylamine a solubility of 0.15 g per liter.

If an excess of potash is present during the precipitation, it is done shown that the solubility of the potassium salt is significantly reduced, so that you can get significantly below 0.15 g per liter.

By using reagents whose potassium salts have a low solubility have, @ one achieves a great practical advantage: because one with. Regeneration the precipitation reagent of the filtrate receives smaller amounts for filtering off.

The method of operation in the method according to the invention is similar to that of the method described in patent 691 366 and its additional patents 704 545, 704 546, 7 1 5 199 and 7 1 5 Zoo.

Embodiments i. 2 # 4.6 # 2 '. 4 '. 6'-hexanitro-3-methyldiphenylamine 51 seawater with a content of 3.509 K Cl received at 20 ° as an additive a solution of i 9.30; g of hexanitromethyldiphenylamine and the equivalent amount of Ca0 in 500 ml of water. The amount of hexanitromethyldiphenylamine corresponds to 90.5% of the amount of K Cl present. The solution was inoculated with previously prepared crystals of the poorly soluble potassium salt. After 1/2 hour the mixture was filtered and the filter cake was stirred with 40 ml of 65% i, ger nitric acid.

The potassium salt of the hexanitro compound was thereby converted into the free, insoluble nitro compound, while the potash went into solution as nitrate. Evaporation of the solution gave 2.78 g of KNOO, corresponding to 58.50% of the potash content of the sea water used.

The filtrate from the seawater precipitation was concentrated. Hydrochloric acid up to pii = 3.0 added, whereby the remainder of the hexanitromethyldiphenylamine was precipitated.

2.2 # 4. 6 # 2 '. 4'-penta nitro-6'-methyl-ldiphenylamin to 51 sea water was dissolved under agitation at 2o ° 1 9, 1 5 g penta nitro-methyldiphenylamine as a calcium salt is added in. 40o ml of water. In order to accelerate the precipitation, previously prepared crystals of the potassium salt were added. After 20 minutes the precipitate was filtered off and washed with water. The filter cake was 3 hours at 20 ° with 25 ml of nitric acid from spec. Weight 1.2 stirred, whereby the potassium salt was completely converted into free nitro compound and potassium nitrate. Evaporation of the filtrate gave 4.40 g of KNO #., Corresponding to 92.5% of the potash content of the seawater used.

The remainder of the nitro compound was in the filtrate from the sea water precipitation precipitated by adding nitric acid up to pi.i = 4, o.

3._ ° .2 # 4 # 6 # 2 '# 4'-Pentanitro-6'-chlorodiphenylamine A solution of 19.8 g of pentanitrochlorodiphenylamine and 1.7 g of CaO in 400 ml of water was added to 51 seawater. The potash salt was precipitated as a fairly finely crystalline, but easily filterable powder, best after previous inoculation. After about 1/2 hour the mixture was filtered and as in Example i with conc. Nitric acid implemented. The yield: 4.04 g of KNO "corresponded to 850! 0 of the calorie content of the seawater used. 4. Tetranitrophenylnaphthylambi 18.75 g of tetranitrophenylnaphthylamine were added to 51 seawater in the form of a solution in 400 ml of milk of lime, which contained slightly more than the calculated amount of Ca0 . the next day was filtered off the sparingly soluble potassium salt and implemented by stirring in i hour with 40 ml ioo! cent nitric acid. evaporation of the filtrate from the Tetranitrophenylnaphthylamin gave 3.04 g KN O3, corresponding to 640.70 of Kaliinhalts of sea water used. By experimenting with other substances, such as 2 # 4 # 6 # 2 '# 4'-pentanitro-6'-methoxydiphenyl- amine and 2 # 4.6.2 '. 6'-pentanitro-4'-methyl- diphenylamine, similar results were found w: e achieved in Examples i to 4.

Claims (1)

PATENT CLAIM: Process for the production of potash from very dilute solutions, e.g. B. seawater, characterized in that in general emeinerung of the method according to the patents 691 366, 704 545, 704 546, 7I5 199 and 7I5 Zoo, in which the potassium from the solutions by adding a soluble dipikrylamine salt, preferably calcium, dipikrylaminat ,; precipitated as potassium dipicrylamine, this separated and treated with an acid and thus obtained on the one hand a solution of the corresponding potassium salt and on the other hand insoluble dipicrylamine. is and the latter after conversion into a soluble Dipikrylaminalz, z. B. calcium dipikrylaminat, is used again and again in the circuit for the treatment of other potassium-containing starting solutions, instead of dipikrylamine other highly nitrated, secondary, aromatic amines, eg. B. hex.anitromethyl-@diphenylamine or pentanitromethyldiphenylamine can be used.