DD213666A1 - PROCESS FOR THE DETOXIFICATION OF AMMONIUM NITRATE-BASED SALT MELTS - Google Patents

Abstract

The invention relates to a method for the elimination of foams on ammonium nitrate salt molten salts in Duengemittelherstellung. It is intended to prevent the foam layer occurring in the production of Kalkammonsalpeter granules and the use of foam-forming lime flours are made possible. It has been found that the foam stability is reduced by cationic ampholytic and nonionic nitrogen-containing chemical substances.

Description

YEB CHEMIBCOMBINATE BIITBRPELD 2290

Process for defoaming aminonium nitrate-containing molten salts

Field of application of the invention

The invention relates to a method for removing foams on ammonium nitrate-containing molten salts in fertilizer production.

Characteristic of the known technical solutions

The production of fertilizers by melting one or more salts and addition of pulverulent components with subsequent granulation takes place in stirred vessels. Specifically, in the preparation of calcium ammonium nitrate are in eine.Ammoniumnitrat "melt at 150 ⁰ C to 160 ⁰ G lime powder and in the production of boron-KAS lime powder and boric acid were stirred and homogenized. The · mixing there is a chemical reaction of the main components. This procedural step

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is determined to a large extent by the properties of the reactants and is made more difficult in cases where the formation of stable foam layers occurs when gaseous reaction products are discharged.

It is a characteristic of natural substances that they have formed over long prehistoric periods and thus exhibit fluctuations in the chemical composition or in their physicochemical behavior. Especially in the Kalkammons'alpeterherst elling is observed that calcite used calcite, z. B. due to bitumen deposits in the limestone layers is wetted differently from the ammonium nitrate melt. Due to the occurrence of gaseous reaction products, a foam layer is produced on the molten salt, which solidifies on cooling, hampers the production process and deteriorates the quality of the fertilizer granules.

So far, the foaming of the molten salt can only be prevented by such foaming lime are excluded from the processing. By mixing foaming lime with non-foaming varieties foaming can be pushed back at a high degree of dilution. However, this technical solution requires additional Lagerauf? / And and is dependent on the availability of non-foaming lime.

Usually, foaming is prevented in aqueous media by adding so-called antifoams in the smallest amount to the aqueous system. In principle, such compounds are bound to the aqueous phase in their reaction and can not be transferred to other systems. In almost anhydrous salt--

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melt, at the relatively high temperatures above the melting point and for strongly oxidizing salts, the known defoamers from aqueous systems are not applicable.

Object of the invention

The aim of the invention is to prevent the occurring on the molten salt in the production of Kalkaamonsalpetergranze, disturbing stable foam layer and thereby to allow the technical use of foam-forming lime flours.

Explanation of the essence of the invention

The invention has for its object to reduce the stability of the resulting foam layer by applying certain chemical and finely divided substances on the interface z \ vischen the solid particles of Kalkmehles and the ammonium nitrate melt phase and to enable the processing of foaming lime flours in the technical process. It has been found that to reduce the foam stability in the molten ammonium nitrate solid substrate-specific effective cationic, ampholytic and nonionic nitrogen-containing chemical substances are suitable, which are distributed in the relevant temperature range above 100 ⁰ C in the melt and at high speed at the interfaces, preferably at relevant pesticide or the impurities contained are adsorbed. In the case of calcium ammonium nitrate production, the pesticide is calcitic lime and its bituminous impurities. As a particularly effective nitrogenous

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Compounds have been found according to the invention cationic surfactants based on aliphatic primary and secondary amines whose organyl radicals are partially unsaturated and contain at least 12 carbon atoms. It is preferred to use salts and quaternary products of saturated and unsaturated fatty amines, the secondary amines derived therefrom, and the ίΤ-alkylated ethylene and propylene diamines.

As effective ampholytic nitrogen-containing compounds Aminobisalkylenphosphonsäuren, preferably IT, lI-bis (phosphonomethyl) glycine ,, used · The substances according to the invention in a concentration of 0.001 to 0.4 mass%, based on the molten salt, on the interface of the solid , preferably the Kalkmehles in the Kalkammonsalpetergewinnung applied by spraying an aqueous solution or suspension of the active substances on the solid, in the case of 'Kalkammonsalpetergewinnung on the lime, or on the resulting foam layer and thereby a good distribution is guaranteed. According to another variant of the invention, the active substance may also be added directly to the solid prior to entry into the melt, in the case of calcium ammonium nitrate extraction to the lime powder, mixed therewith and added to the ammonium nitrate melt.

On the other hand, the effectiveness of the substances is greatly reduced by first adding them to the ammonium nitrate melt and then adding the foam-forming solid, in the case of calcium ammonium nitrate extraction, the lime powder. The suitability of the active substances in the ammonium nitrate melt system was determined in a laboratory foam test as follows:

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In a cylindrical koi "ben with a flat bottom and magnetic stirrer are melted 40 g of ammonium nitrate, the • temperature of the melt is measured with a thermometer, after having set a temperature between 160 and I65 ⁰ G., 13 g of a foamy acting Kalkmehles are added and The foamy lime powder shows a stable foam height of 6 cm in this foaming test When the chemical substances according to the invention are added by special introduction into the molten salt, the stability of the foam layer is reduced S unstable foam heights of 1 to 2 cm are obtained for well-active substances The substances are added in amounts such that their concentration in the molten salt is between 0.001 and 0.4% by mass.

The tests with this foam test were carried out on typical representatives of the following classes of substances: fatty alcohols and ethylene oxide adducts, pettamines, their salts and quaternary products, fatty acids and their salts, phosphoric and phosphorous acid esters and amides, dialky-1-hydrozyphosphonates, dithiocarbaminates, aldimines, ethylene and Propylenediamines and their salts, amine oxides, phosphine oxides, paraffinosidation products and siloxane derivatives. The invention will be explained with reference to the following examples of the melting system ammonium nitrate calcite.

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Ausführungsbeispiei Example 1

To 13 g of a sciiaumbildenden Kalkinehles, which forms a stable foam layer of 6 cm in the foaming test, 15 mg of the substance 3> T, i7-bis (ph.phosphonomethyl) glycine, which in 2 ml dest. Water are dissolved, with motion aufgebüst on the callus meal. A lime flour modified in this way with H, H-bis- (phosiphonomethyl) glycine shows a foam height of 2 cm in the foaming test, no stable foam layer is formed.

Example 2

A mash consisting of 40 g of ammonium nitrate and 13 g of lime powder, which has a stable foam layer of β cm after a reaction time of 2 minutes at I0O G, is sprayed with 2 ml of an aqueous suspension of 15 g of Hesadecylamin hydrochloride in 2 ml of water Surface reaction, the foam layer goes back to 2.5 cm. rTach complete distribution of the substance Hesadexylamin hydrochloride and reaction in the melt, a stable foam layer is no longer formed.

Example 3

In 13 g of a foam-forming Kalkmehles having a stable foam layer of 6 cm in the foaming test, 15 mg of a partially unsaturated aliphatic primary amine alkyl chain lengths C ₁ / - and CQ, containing 15 to 20 % of secondary amine, finely divided and intense in the mortar

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mixed. In this way with partially unsaturated amine it pretreated lime powder in the foaming test to a foam height of 1.5 cm, no stable foam layer is formed.

Example 4

Sine mash, consisting of 4-0 g of ammonium nitrate and 13 g of lime, which forms after a reaction time of 2 minutes at 16O ⁰ G, a stable foam layer of β cm, with an aqueous suspension of 7.5 mg of H-Octadecvl propylendiamindioleat in 2.5 ml of water sprayed * After a reaction time of 2 minutes, the height of the foam layer goes back to 2 cm and after v / erigerer action a stable foam layer is no longer formed.

Example 5

Sine mash, consisting of 40 g of ammonium nitrate and 13 g of lime powder, which after a reaction time of 2 minutes at 160 ⁰ C forms a stable foam layer of β cm, is sprayed with a solution of 7.5 mg Octadecyltrimethylammoniumchlorid in 2.5 ml of water. After 2 minutes of sintering time, the height of the foam layer goes back to 2.5 cm, so that it does not develop any further.

Example 6

Sine mash best.ehend of 40 g of ammonium nitrate and 13g lime powder, which forms a stable foam layer of β cm after a reaction time of 2 minutes at 160 G ^0, is treated with a suspension of 15 mg

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of a sulfate of partially unsaturated aliphatic primary (80-85 %) and secondary (15-20 %) amine S of the alkyl chain lengths C- / Cq in 2 ml of water sprayed, after complete dispersion becomes an unstable foam height of 1.5 cm reached.

Example 7

A mash consisting of 40 g Aimnoniumnitrat and 13g lime, which after a reaction time of

2 minutes at 16O C forms a stable foam layer of β cm, is filled with a suspension of

30 mg of a hydrogen phosphate of primary hexadecylamine (molar ratio 1: 2) in 2 ml sprayed V / asser.

After a surface reaction, the foam height is reduced to 2.5 cm in 2 minutes.

Claims (4)

- 9 - 2290 Erfindunpsanspruch 1. A method for reducing the foam stability of ammonium nitrate-containing salt melts in the production of fertilizers, characterized in that in the melt system ammonium nitrate pesticide substrate-specific effective cationic ampholytic 'or nonionic nitrogen-containing surfactants are added, distributed in the relevant temperature range above 100 ⁰ C in the molten system and at Interfaces, preferably on the pesticide adsorbed. 2. The method according to item 1, characterized in that as cationic nitrogen-containing surface-active compounds aliphatic primary or secondary amines, preferably with organyl radicals which are partially unsaturated and contain at least 12 carbon atoms, their salts and Quartärnierungsprodukte be used. 3. The method according to item 1, characterized in that are used as ampholytic nitrogen-containing compounds Aminobisalkylenphosphonsäuren, preferably IT, iT-3is- (phosphonomethyl) glycine. 4. The method according to points 1 and 2 or 3> characterized in that the cationic, ampholytic or nonionic nitrogen-containing surface-active compounds before the Ξιη-trag on the solid component of the melt system, preferably in aqueous solution 'or suspension, are distributed. • 10 - 229ί Process according to items 1, 2 or 3, characterized in that the cationic ampholytic or nonionic nitrogen-containing surface-active compounds are finely distributed on the resulting foam layer of the melt, preferably by spraying in aqueous solution or suspension.