DE1048563B - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT LETTER 1 048 REGISTRATION DAY: '

NOTICE DEH REGISTRATION AND ISSUE DBB EDITORIAL:

EDITIONS PATENT LETTERING:

DBP 1048 563 small. 121 6

INTERNAT. KL. C 01 d OCTOBER 23, 1957

JANUARY 15, 1959 JULY 9, 1959

AGREES WITH AN EXEMPLARY LETTER 1 MB 56Ϊ (B «517 TVa / 12 1)

It is known that alkali nitrates can be prepared from alkali chlorides and nitric acid with the aid of ion exchangers. The reaction is generally carried out so that in the first 'stage (loading) an aqueous alkali metal chloride solution, for. B. potassium chloride solution, is passed through a column filled with a cation exchanger in the H + (acid) form, the exchanger being converted into the K ⁺ (salt) form and free hydrochloric acid according to the equation

R-H + KCl - ► R-K + HCl (I)

arises.

After complete loading and, if necessary, subsequent washing of the exchange column with Water, the exchanger is regenerated with aqueous nitric acid solution, with the exchanger is converted back into the H + form and an aqueous nitrate solution from the exchange column ao flows out. This regeneration lies in the equation

R - K + ENT ₃ = ► RH + KNO ₃ (II)

underlying.

The process can be carried out continuously if one considers the regeneration and, if necessary Washing out of the exchanger with water is followed by a loading with alkali chloride solution, then regenerated again etc.

A complete loading of the exchanger according to equation (I) or regeneration according to equation (II) is only possible if a considerable excess of alkali chloride or nitric acid is passed through the exchange column.

The degree of implementation of the outflowing solutions

HCl

, HCl + KCl

respectively.

KNO,

ENT ₃ + KNO ₃

is initially 100%; after a certain time, the content of unconverted K Cl or HNO ₃ increases, ie the degree of conversion decreases. Complete loading or regeneration is recognized by the fact that pure, ie, hydrochloric acid-free KCl solution or pure, ie, KNO ₃ -free nitric acid solution finally flows out of the treated exchange column (degree of conversion = 0).

It has been found that the economics of this process are considerably better and depending on Desires and requirements of very pure alkali nitrate or less pure z. B. suitable as a fertilizer Products can be obtained by following the process in a series of cascading,

30th

35

40

45

SO Continuous process for the production of alkali nitrates

from alkali chlorides and nitric acid using cation exchangers

Patented for:

Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen / Rhein

Dr. Günther Hamprecht, Limburgerhof (Palatinate), and Dr. Jens-Peter Siegfriedt _t Ludwigshafen / Rhein, have been named as the inventor

25th of alkali chloride solution or aqueous nitric acid solution "continuously flowed through exchange columns carried out, with one at the end of each column only the almost completely converted peak fraction of the solution treated in each case withdraws and recycles the circuit and the remaining portion of the flow and an amount equivalent to the withdrawn peak fraction is fresher Alkali chloride solution or nitric acid solution of the next, freshly regenerated with nitric acid or freshly treated exchange column with alkali chloride solution. The total amount of den Columns fed loading or regeneration solution is dimensioned so that the degree of conversion of the final solution flowing out is almost 0, but not more than 1%, d. H. that the exchanger is close to 100, but is at least 99% loaded. The count of for the fully continuous implementation of the process necessary pillars results from the. total amount required under the stated conditions Loading and regeneration solution plus an optionally required amount of water for Washing out the columns between loading and regeneration or "between regeneration and loading and the capacity of the exchanger. A An arrangement of eight to sixteen columns is generally sufficient. After a certain start-up time if the columns are in operation, a stationary supply

909 553/220

1 048 5S3

stood a, which allows one of the capacity of the at the end of each column with each loading or regeneration Take the appropriate amount of hydrochloric acid or alkali nitrate from the column. The degree of implementation of the received Solutions can be brought up to over 98%.

It is advisable to use alkali or alkali metal instead of pure alkali metal chloride solution for loading the columns Alkaline chloride solution containing ammonium hydroxide, the OH concentration of which is 0.5 to 20 g, mainly 3 to 10 g per liter of solution. This measure takes into account the fact that due to the selectivity of the exchanger is the constant of mass action, for example of the exchange of hydrogen ions by potassium ions

"Ab =

1 * 3

[HÜ

where HJ is the hydrogen ion concentration on the exchanger, HJ. that of the solution, KJ the potassium ion concentration the solution, KJ. which means on the exchanger is different from 1, d. i.e. that of the Both reactions (1) and (II) run in the directions indicated, one of which is easier and more complete than the other.

Experience has shown that the customary strongly acidic cation exchangers based on polystyrene the regeneration according to equation (II) can be carried out more easily than the loading according to equation (I).

When using alkali metal or ammonium hydroxide-containing alkali metal chloride solution, the for the one-time complete loading of a single column required total amount of alkali chloride solution compared to working with pure alkali chloride solution by approximately 20%, since the last free Hydrogen ions on the exchanger are difficult with a neutral salt, but very easy with a free base can be exchanged for potassium or ammonium ions.

An alkali hydroxide solution is used for the production of very pure alkali nitrates for chemical purposes. which contains the same cation as the alkali metal nitrate to be produced, while for the Manufacture of products for fertilization purposes the use of ammonium hydroxide as an additive to Alkali chloride solution recommends.

It is advantageous to carry out the loading of the exchanger columns by treatment with from below the above-mentioned alkali chloride solution, d. H. in the ascending liquid flow, while the aqueous nitric acid solution is fed in the opposite direction for regeneration. Through this it is achieved that both during loading as well as • during regeneration are always specifically lighter above the. Specifically heavier liquid is located, which limits the mixing of acid and salt will. On the other hand, this causes the opposite direction of flow of alkali chloride solution and aqueous nitric acid prevent the exchange grains from being constantly swirled up and thus prevented a constant increase in the flow resistance in the pipe, which ultimately leads to clogging can lead.

Between the treatment of the exchange columns with alkali chloride solution. and treatment with diluted Nitric acid, the columns can be washed out with water and the columns containing alkali chloride Washing water to dissolve fresh alkali chloride and the washing water containing nitric acid use to dilute concentrated nitric acid.

For example

In a series of exchange columns connected in series, each with 3.5 kg of a strongly acidic Cation exchanger (sulfonated styrene-divinylbenzene copolymer) are filled (total

ίο capacity per column 12.6 equivalents), 101 solution, which contains 255 g (~ 3.4 equivalents) KCl per liter, are passed through the first column, which is completely in the H ^{+ form.} The first 4 liters of the passage through this column are withdrawn from the circuit and worked up on hydrochloric acid. The amount of hydrochloric acid obtained is 230 g; its potassium chloride content is 2.9 g.

The subsequent portion of the run-through and then 5 liters of fresh potassium chloride solution of the above concentration are fed to the second column ^{, which is completely in the H + form.} 51 hydrochloric acid solution with a content of 346 g HCl and 3.4 g KCl are withdrawn from this run-through, while the remaining run-through of this column and then 5 l fresh potassium chloride solution of the specified concentration are fed to the third column. 5 liters of hydrochloric acid solution containing 399 g of HCl and 3.0 g of KCl are drawn off from the passage through the third column.

The remaining run of the third column and 5 liters of fresh potassium chloride solution become the fourth Pillar abandoned. 61 hydrochloric acid solutions are withdrawn from the passage through the fourth column, which contain 437 g HCl and 1.2 g KCl. The remaining run and 5 liters of fresh potassium chloride solution will be fed to the fifth column. The passage through the fifth column becomes 61 hydrochloric acid solution withdrawn with a content of 456g HCl and 3.5 KCl. The rest of the pass from the fifth Column and 5 l of fresh potassium chloride solution are fed to the sixth column, from the 6 l of hydrochloric acid solution with 463 g of HCl and 4.5 g of KCl are removed.

If the experiment is continued in the manner described in further columns, the following will become Columns always obtained an amount of hydrochloric acid of about 450 to 470 g each, which is the capacity of the individual Column corresponds. The potassium chloride content of these solutions varies between 0 and 10 g. That means that the degree of conversion in the hydrochloric acid solution emerging from the respective column is always is higher than 98.5% and a steady state is established for the loading from the sixth column on Has.

For the purpose of regeneration, 7.01 of a 5% nitric acid are added to the first column, which is ^{completely in the K +} form after it has been fully loaded and briefly washed out. For work-up on potassium nitrate 31 with a content of 955 g of KNO _a and 5.3 g of free HN O _3, the solution flowing through the column is branched off. The remainder of the flow and 41 5 η-nitric acid are applied to the second column, from which for work-up on potassium nitrate · 4 1 with a content of 1193 g KNO ₃ and 22.3 g free. ENT _{3 can be} branched off. . The remainder of the run-through from the second column and 3 1 5 η-nitric acid are fed to the third column. From it, 5 l of the pass, which contain 1302 g of KN O ₃ and 9.2 g of free HNO _3, are deducted for the work-up, work-up on potassium nitrate.

Claims (4)

From the fourth column onwards, between 1250 and 1300 g of potassium nitrate with a content of 5 to 20 g of free nitric acid are obtained from the previous column after branching off the first 5 liters and adding 3 1 5 η-nitric acid. The results show that the degree of conversion of the total solution is always greater than 97% and that a steady state has been established during the regeneration as early as the fourth column. ip Example 2 Through an identical column with the same capacity, in which the exchanger is completely in the H + form, firstly a neutral and secondly an ammoniacal potassium chloride solution are passed. The potassium chloride content of the solution is 255 g / 1 in each case, the ammonia content of the ammoniacal potassium chloride solution is 6.5 g / 1. The following are required for full loading of the exchanger: in the case of ... 11.70 l = 2970.g = 39.8 equivalents of KCl, in case of 2 ... 9.09.1 = 2300 g = 30.9 equivalents of K Cl + 3, 45 equivalents 1NH3 (total 34.35 equivalents). The amount of KCl saved in case 2 is 5.45 equivalents, corresponding to 13.7% of the amount required in case 1. From the passage through the column, 4 liters each are branched off, which in the case 1 ... 235 g HCl in the case 2 ... 230 g HCl 35 with a purity of> 99%. The remainder of the run is passed through a freshly regenerated second column to which sufficient potassium chloride solution or ammoniacal potassium chloride solution of the above concentration is then added that the column is completely loaded. The quantities required for this are in the case 6.3 1 = 1595 g = 21.4 equivalents of KCl,. . in case 2 4.3 1 = 1245 g = 16.7 equivalents of KCl and NH3; ie 4.7 equivalents - 17.3% less than in FaW 1. From the passage through the second column, the first, more than 99% converted fractions are again branched off, the remainder is passed through a third column and then as much potassium chloride solution or ammoniacal potassium chloride solution of the above concentration added until the column is completely loaded. The amounts required for this are in the case of 1 ... 6.6 1 in the case 2 ... 4.01 From the fourth column on, when using ammoniacal potassium chloride solution according to case 2, the amount of solution to be added is constant, namely 3.8 1 , while it continues to rise when using neutral potassium chloride solution according to case 1. Patent claims: 1. Continuous process for the production of alkali nitrates from alkali chlorides and nitric acid by treating an aqueous alkali chloride solution with a cation exchanger and regenerating the exchanger with aqueous. Nitric acid solution, characterized in that the process is carried out in a series of sequential, alkali metal chloride solution or aqueous nitric acid solution through which exchange columns flowed through, with one on At the end of each column, only the almost completely converted top fraction of the respective treated solution is withdrawn from the circuit and worked up, and the remaining portion of the . Throughput and an amount of fresh alkali chloride solution equivalent to the withdrawn peak fraction or nitric acid solution of the next freshly regenerated with nitric acid or with alkali chloride solution freshly treated exchange column feeds. 2. The method according to claim 1, characterized in that one starts from alkali or ammonium hydroxide-containing alkali metal chloride ^{solution, the OH -} concentration of 0.5 to 20 g, preferably 3 to 10 g, per liter of solution. 3. The method according to claim 1 and 2, characterized in that the alkali metal chloride solution from bottom to top and the nitric acid solution from top to bottom through the exchanger columns leads. 4. The method according to claim 1 to 3, characterized in that there is between the treatment the exchange columns with alkali chloride solution and the treatment with dilute nitric acid each column was washed out with water and the washing water containing alkali chloride was used to dissolve it of fresh alkali chloride and the nitric acid ^ containing washing water to dilute concentrated Nitric acid used. Ö 809 729/187 1.59 (909 553/220 7.59)