US1082781A - Process for the dehalogenization of halogeniferous nitrates. - Google Patents

Description

UNITED STATES PATENT OFFICE.

CARL UEBELQor HEIDELBERG, GERMANY.

PROCESS FOR THE DEHALoGENIzATIoN or HALoGENIrERoUs NITRATES.

No Drawing.

To all whom it may concern:

Be it known that I, CARL UEBEL, a resident of Heidelberg, in the State of Baden, Germany, have invented certain new and useful Improvements in Processes for the Dehalogenization of Halogeniferous Nitrates, of which the following is a specification.

The naturally occurring nitrates and, especially Chili saltpeter which is used in large quantities for manurial purposes and in chemical industry contain varying amounts, depending on their degree of purification, of chloride. chlorates and perchlorates or iodids, iodates and periodates, together with small quantities of bromin compounds and stages of oxidation thereof; These impurities are extremely deleterious for many purposes for which commercial saltpeter is employed, especially in the manufacture of nitric acid and they give riseto not inc0nsiderable difficulties and losses in manufacture.

As is well-known the manufacture of nitric acid is generally carried outby the distillation of Chili saltpeter with sulfuric acid when the halogenlcompounds contained in the saltpeter are likewise decomposed and escape partly at the beginning and partly at the end of the operation, giving rise to contamination of the condensed nitric acid with chlorin and iodin, and also rendering difficult the complete condensation of the nitrous gases evolved owing to the formation of nitrosyl compounds. Thus in the manufacture of nitric acid in order to obtain a good yield and pure nitric acid of a high avera e concentration, the so called refined or doub e refined salt-peter with the lowest possible chlorin content is almost exclusively employed, since it has been found by experience that the percentage yield varies approximately in the same manner as the nitrate content of the saltpeter, so that for example when using unrefined saltpeter ('9 l95% NaNO the yield of nitric acid is about.

9495% of that required by theory, while when using refined saltpeter (97-98% NaNO the yield is about 98% of that required by theory, while the average concentration of the acid produced is essentially higher; obviously it is presupposed that in both the above cases equally good condensation apparatus is employed.

When using Chili saltpeter for manurial purposes its contamination by chlorids and iodids is of less importance, but perchlo- Speci fioation of Letters Patent.

Patented Dec. so, 1913.

Application filed December 4, 1912. Serial No. 734,888.

rates are to be feared as plant poisons. The

manufacture of saltpeter-superphosphates when using unrefined saltpeter is an extremely unpleasant operation owing to the chlorin content of the saltpeter, since the half combined phosphoric acid liberates chlorin and iodin and the mixed manure thus acquires a disagreeable smell, becomes very hygroscopic and destroys the sacks; moreover in some circumstances spontaneous ignition may occur owing to the interaction between the superphosphates and the halogen compounds of the saltpeter. It is only due to these unpleasant properties of the compound manure of superphosphate and unrefined saltpeter that it has hitherto been little introduced in agriculture and is unsuitable for export.

Now it has been found that the above halogen compounds which have been mentioned as injurious impurities of the saltpeter can be removed in a simple manner by heating with a small quantity of sulfuric acid, calculated to be equivalent to the content of halogen compounds or with an equivalent amount of an acid sulfate (bisulfate, polysulfate). By these means the saltpeter is technically completely freed from the halogen compounds, and since according to the present invention the dechlorination is effected at a rather high temperature a dehydration or calcination of the saltpeter simultaneously occurs, thus rendering it of full value with reference to its nitrate content.

To carry out the process in practice it is not particularly necessary for the halogeniferous saltpeter to be intimately mixed with the dechlorinating agent, since if too much of the dechlorinating agent (the active acid radical of which is capable of liberating nitric acid from nitrates), is present in one part of the mixture nitric acid will be evolved, which for its part owing to evaporation during the dechlorinating process penetrates to and dechlorinates the particles of saltpeter which were not in contact stroyed. For most technical objects sulfuric acid, bisulfate or polysulfate will be the most suitable and rational dechlorinating agents. However, should it be desired to obtain by the dechlorinating process a high percentage saltpeter as free as possible from contamination by foreign salts such as sulfates, etc., then nitric acid is the suitabledechlorinating agent. Moreover for the techand that the moist crystalline meal adhering to the crystals contains the main quantity of the halogens which thus essentially arises from the adhering mother-liquid.

The process can be carried out in any desired closed mixing and transport apparatus, heated by steam or directly fired; the apparatus may be made of cast iron or wrought iron and the mixture, which is to be heated, may be introduced and removed continuously or discontinuously.

For removing and, if desired utilizing the hydrochloric acid, chlorin, bromin and iodin vapors which are evolved possibly with a small quantity of nitrosyl chlorid, which may have been produced by a small excess of the dechlorinating agent, the dechlorinating apparatus may be connected with a washing, absorption or condensation apparatus.

The temperature necessary for dechlorination may be fixed within wide limits, and may vary from gentle heating to the melt ing point of the saltpeter. There is a complete decomposition of the halogenids and perchlorates at 100, but the small quantity of iodates contained in the saltpeter will only be decomposed at temperatures over 100; it is suiiicient for all practical purposes to eifect the dechlorination by heating the apparatus to 100-150 centigrade.

The advantages of the process are at once. clear for the various purposes for which saltpeter is employed in industry and agriculture, since when using saltpeter which has been treated according to the present invention all the disadvantages are com pletely avoided which occur as explained which has not been dechlorinated, thus ca-using damage to the workers and the apparatus.

What I claim as newand desire to secure by Letters Patent is r 1. The process for removing halogens from nitrates by mixing the nitrate with an acidic agent capable of decomposing the halogen compounds, the amount of acid being substantially equivalent to the amount of halogen present, without previous dissolving of the nitrate, and heating the mix- I ture in order to decompose the halogen compound and to drive off the halogen.

2. The process for removing the halogens from nitrates in which the nitrate is mixed with acidic substances in an -amount substantially equivalent to the amount of halogen present, without previous dissolving, and heated to 100150 centigrade.

3. The process for removing the halogens from Chili saltpeter, in which the Chili saltpeter is mixed with an acidic substance capable of decomposing the halogen compounds in an amount substantially equivalent to the amount of halogen present without previously dissolving the saltpeter, and

heated to temperatures at which the halogen compounds are decomposed and the halogen is removed. 7

4. The process of removing 7 from Chili saltpeter in which the Chili saltpeter is mixed with acidic substances containing the S0 group in an amount substanthe halo-gens tially equivalent to the amount of halogen 7 present, without previously dissolving the saltpeter, and heated to 100150 centi grade. 7

In testimony whereof I have hereunto set my hand.

CARL UEBEL.

WVitnesses:

FRANZ WVmLovroR, J EAN GRUND.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C.