DE112217C - - Google Patents

Description

In the production of ferrocyaneal alkalis (according to the Ku h η heim'sehen process) the Masses that were used to purify the luminous gas, initially with hot water leached to remove the soluble ammonium salts. The residue is then with mixed with pulverized quick lime and the mixture in closed vessels Subject to the action of water vapor. The insoluble Berlin blue is here in soluble calcium ferrocyanine transferred. The concentrate ferrocyan calcium solution leaves behind after the addition of potassium chloride during boiling, almost insoluble ferrocyanic potassium calcium. This is now heated with potassium carbonate, whereby calcium carbonate and soluble ferrocyanic potassium, which are allowed to crystallize, are formed. If you want to produce ferrocyan sodium, so Sodium carbonate is added to the ferrocyanic calcium. Calcium carbonate is obtained in this way and a solution of ferrocyan sodium which is crystallized. The mother liquors which result from the crystallization of ferrocyan sodium, as well as the liquid, which has been separated from the ferrocyane potassium calcium precipitate will not further processed.

These mother liquors are now to be used according to the present process for the production of cyan and ferrocyanic alkalis can be made usable.

It has been found that these mother liquors, in addition to a certain amount of Compounds of hydrocyanic acid considerable amounts of carbonylferrocyanic compounds contain.

The presence of a new cyano iron compound was confirmed by Mahla (Ber. D. D. Ges. XXII, S. im) in the cold, aqueous extract of used gas cleaning compound found. This author writes: If by fractionated precipitations by means of ferric chloride which was produced in a cold, aqueous extract of used gas cleaning mass Berlin blue separated or. is separated by filtration after each precipitation, so finally succeeds in obtaining a precipitate with a further addition of ferric chloride which has a deep dark purple color and differs from Berlin blue in many of its properties. ”He then says further that the solution of the violet precipitate decomposed with alkalis cannot be evaporated unchanged.

The exact constitution of this new compound Cy ^ Fe CO · K ₃ (carbonylferrocyane potassium) was established by Müller (Compt. Rend. 104, p. 994), who quantified the content of carbon monoxide. It says there: “This new ferrocyanic compound will be used with the exclusion of air at 300 to 400 ° C. heated until the evolution of gas ceases, it loses 9.05 pCt. their weight and delivers 8.33 pCt. Carbon dioxide which can be absorbed by a solution of copper chloride. The formula Fe CO Cy. K ₃ requires 8.47 pCt. Carbon dioxide. During this heat-induced decomposition, common ferrocyanic potassium and iron cyanide are also formed

To get the carbonylferrocyan compounds, which are in the remaining mother-

lyes from ferrocyan salt production accumulated have, as well as the small amount of ferrocyanic compounds, which remained in solution, for the production of cyano and ferrocyan compounds The mother liquors can be made usable according to the present process mixed with iron chloride to bezw the Carbonylferrocyanalkalien. alkaline Earths contained therein in the form of violet carbonylferroterricyanide, which are found in The solution in the ferrocyan compound is to be found as Berlin blue. The precipitation will collected, washed and decomposed with a solution of potash, soda or an alkali carbonate. Here, iron oxide hydrate separates out, which in turn turns into iron chloride Weilerer use can be transferred, while the Carbonylfe.rrocyanalkali, as well Ferrocyanalkali remains in solution. This solution is evaporated to dryness and the Residue of carbonylferrocyan alkali and ferrocyanur in the following manner in cyanur and Ferrocyanür transferred:

In order to produce alkali metal cyanides, the residue is made according to the Erlen Meyer method for the production of cyanides from ferrocyanures heated with metallic sodium (Ber. D. D. Former Ges. IX, p. 1840). The implementation takes place according to the equations:

1) (CNJ ₅ Fe-C 0-K ₃ + Na ₂ =

3 K CN + 2NaCn + Fe + CO,

2) (CN) ₆ FeK, + Na ₂ = 4KCN + zNaCN + Fe '.

In order to obtain ferrocyanic alkalis from the same residue, the same is spread out in thin layers on ordinary iron sheets, covered with powdered iron and heated moderately. The reaction is propagated in the whole mass and is over in a short time. Under the action of heat, the carbonylferrocyanic alkali decomposes into ferrocyanur and cyanoalkali. In order to avoid the formation of gyanates ^v from the cyanur by the oxygen in the air during heating, the mass is, as already mentioned, covered with a thin layer of powdered iron. This also serves at the time of leaching of the reaction product to convert the cyanuric acid formed into ferrocyanic uranium. After cooling, the mass is leached in a suitable manner and the solution of ferrocyanic alkali crystallized.

Claims (2)

Patent claim: Process for the preparation of cyano and ferrocyanic alkalis from the carbonyl errocyan compounds and ferrocyan compounds, which are contained in the mother liquors remaining in the manufacture of ferrocyan compounds from gas cleaning mass, characterized in that the alkalis are mixed with iron chloride and the resulting precipitate is averaged Alkali (caustic alkali, alkali carbonate etc.) decomposed, the solution freed from iron oxide hydrate evaporated to dryness and the dry residue obtained either: 1. Glows with metallic sodium, causing Cyanalkali compounds are obtained, or 2. Covered with powdered iron and heated moderately, creating ferrocyanic compounds be won.