DK165875B

DK165875B - PROCEDURE FOR THE MANUFACTURE OF AMMONIUM NITRATE AND CALCIUM CARBONATE CONTAINING FERTILIZERS

Info

Publication number: DK165875B
Application number: DK121987A
Authority: DK
Inventors: Robert E Nitzschmann; Karl Heinz Zapp; Hermann Pottgiesser
Original assignee: Basf Ag
Priority date: 1986-03-11
Filing date: 1987-03-10
Publication date: 1993-02-01
Also published as: MA20891A1; NO870985L; EP0236972A3; NO170403B; DE3607994A1; DK121987A; NO170403C; DK121987D0; NO870985D0; ZA871709B; ATE61788T1; DZ1056A1; DE3768677D1; EP0236972B1; DK165875C; EP0236972A2

Abstract

For the preparation of the fertilisers, calcium carbonate which has been obtained by the reaction of calcium nitrate with ammonia and carbon dioxide or ammonium carbonate in aqueous solution is introduced into ammonium nitrate melts. A calcium carbonate is employed which contains ammonium nitrate and water, with the proviso that the sum of the ammonium nitrate and water contents does not exceed 25 % by weight, the water content is 4 to 11 % by weight and the ammonium nitrate content is at least 1 % by weight.

Description

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DK 165875 BDK 165875 B

Det er kendt at fremstille ammoniumnitrat- og calciumcar-bonatholdige gødningsmidler ved blanding af ammoniumni-tratsmelter med fint formalet og tørret calciumcarbonat (DE-C-691 686, Process Technologies for Nitrogen 5 Fertilizers, U.S. Department of Commerce, 1978, side 51-53). I afhængighed af den tilsatte calciumcarbonatmængde opnår man gødningsmidler med varierende N-indhold.It is known to produce ammonium nitrate and calcium carbonate fertilizers by mixing ammonium nitrate melts with finely ground and dried calcium carbonate (DE-C-691 686, Process Technologies for Nitrogen 5 Fertilizers, US Department of Commerce, 1978, pages 51-53 ). Depending on the amount of calcium carbonate added, fertilizers of varying N content are obtained.

Som calciumcarbonat kan man enten anvende naturlig, for-10 malet og tørret kalksten eller fældet calciumcarbonat.As calcium carbonate, either natural, milled and dried limestone or precipitated calcium carbonate can be used.

Dette fældede calciumcarbonat udvindes af calciumnitrat-tetrahydrat (Ca(N0^)2·41^0), således som dette fremkommer i betydelige mængder ved salpetersyreoplukning af råphos-phater i henhold til Odda-metoden. Dette calciumnitratte-15 trahydrat bliver med ammoniak og carbondioxid eller am-moniumcarbonat i henhold til reaktionsskemaetThis precipitated calcium carbonate is recovered by calcium nitrate tetrahydrate (Ca (NO₂) 2 · 41 ^O), as is found in significant amounts by nitric acid uptake of crude phosphates according to the Odda method. This calcium nitrate tetrahydrate becomes ammonia and carbon dioxide or ammonium carbonate according to the reaction scheme

Ca(N0_)^.4Ho0 + 2NH0 + C0~ - CaC0o + 2NH.N0_ + 3H-0 '322 3 2 3 43 2 20 omdannet til calciumcarbonat og ammoniumnitrat. Efter omsætningen separeres den ca. 65 % NH^NO^-opløsning fra det fældede calciumcarbonat. Ammoniumnitratopløsningen inddampes, mens calciumcarbonatet vaskes og tørres. Det således behandlede calciumcarbonat sættes derpå til den op-25 koncentrerede ammoniumnitratopløsning og den fremkomne flydende blanding overføres ved granulering eller pruning til det kornformede gødningsmiddel (jvf. Ullmanns Encyklopådie der Technischen Chemie, 4. oplag, bind 7, side 518-519). Det udvaskede og tørrede calciumcarbonat 30 har et fugtighedsindhold på under 0,05 vægt-% og et ammo-niumnitratindhold på ca. 0,15 vægt-% (IFA Technical Conference, Paris, 1984, Preprints side 18-11 til 18-13, ISMA Technical Conference, 1976, Den Haag, Preprints side 224-226). Udvaskningen og tørringen repræsenterer omstæn-35 delige trin, fordi udvaskningen skal gennemføres i flere trin, og fordi tørringen af det efter filtreringen fugtige materiale, der indeholder ca. 13 vægt-% fugtighed,Ca (N0 _) ^. 4Ho0 + 2NH0 + C0 ~ - CaCOO + 2NH.N0_ + 3H-0 '322 3 2 3 43 2 20 converted to calcium carbonate and ammonium nitrate. After the reaction it is separated approx. 65% NH 2 NO 2 solution from the precipitated calcium carbonate. The ammonium nitrate solution is evaporated while the calcium carbonate is washed and dried. The calcium carbonate thus treated is then added to the concentrated ammonium nitrate solution and the resulting liquid mixture is transferred by granulation or pruning to the granular fertilizer (cf. Ullmanns Encyklopådie der Technischen Chemie, 4th edition, Vol. 7, pages 518-519). The washed and dried calcium carbonate 30 has a moisture content of less than 0.05% by weight and an ammonium nitrate content of approx. 0.15% by weight (IFA Technical Conference, Paris, 1984, Preprints pages 18-11 to 18-13, ISMA Technical Conference, 1976, The Hague, Preprints pages 224-226). The leaching and drying represent tedious steps because the leaching has to be carried out in several steps and because the drying of the moistened material after filtration containing approx. 13 wt% moisture,

DK 165875 BDK 165875 B

2 kræver høj energitilførsel. Det ved udvaskningen fremkomne vand indeholder ammoniumnitrat, og det må af hensyn til miljøbeskyttelsen ligeledes oparbejdes under højt energiopbud. På den anden side skal man ved disse omstæn-5 delige skridt, der omfatter udvaskning og tørring, undgå de ved tilsætningen af calciumcarbonatet til ammoniumni-tratsmelten iøvrigt indtrædende forstyrrelser hidrørende fra stærk skumning.' Desuden opnår man ved forarbejdning af fugtig, udvasket kalk, der er opnået ved den i det fo-10 regående beskrevne metode, kornede produkter, der er lidet slidstærke.2 requires high energy supply. The water produced during the leaching contains ammonium nitrate and it must also be reprocessed under high energy supply for environmental protection reasons. On the other hand, in these elaborate steps which include leaching and drying, the disturbances resulting from strong foaming must be avoided by the addition of the calcium carbonate to the ammonium nitrate melt. In addition, the processing of moist, leached lime obtained by the method described in the foregoing is obtained with grain products which are not hard-wearing.

Det er opfindelsens formål at tilvejebringe en fremgangsmåde til fremstilling af ammoniumnitrat- og calciumcarbo-15 natholdige kornede gødningsmidler, ved hvilken calciumcarbonatet, der er fremstillet ved omsætning mellem calciumnitrat med ammoniak og carbondioxid eller ammonium-carbonat i vandig opløsning, indføres i smelter af ammoniumnitrat og de fremkomne flydende blandinger overføres 20 til den kornede form, ved hvilken disse ulemper ikke optræder, og hvor man i det mindste delvist ikke behøver at udføre de hidtil nødvendige vaske- og tørreoperationer og samtidigt opnår et produkt, der tilfredsstiller de krav, der stilles dertil hvad angår slidstyrke.It is an object of the invention to provide a process for preparing ammonium nitrate and calcium carbonate-containing fertilizers in which the calcium carbonate prepared by reaction of calcium nitrate with ammonia and carbon dioxide or ammonium carbonate in aqueous solution is introduced into ammonium nitrate melts and the resulting liquid mixtures are transferred to the granular form in which these disadvantages do not occur and where at least in part the necessary washing and drying operations need not be carried out and at the same time obtaining a product which satisfies the requirements set therein in terms of wear resistance.

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Fremgangsmåden ifølge opfindelsen er ejendommelig ved det i den kendetegnende del af krav 1 angivne. Herved opfyldes opfindelsens formål.The method according to the invention is characterized by the method of claim 1. The object of the invention is thus fulfilled.

30 Et calciumcarbonat, der svarer til de angivne krav, kan enten fremstilles direkte ved omdannelsen af calciumnitrat i vandige opløsninger med ammoniak og carbondioxid eller ammoniumcarbonat og frafiltrering, eller man behøver kun forholdsvis ringe mængder vaskevand eller ammo-35 niumnitratopløsninger for at indstille vand- og ammonium-nitratindholdene ifølge opfindelsen.A calcium carbonate that meets the requirements can either be prepared directly by the conversion of calcium nitrate into aqueous solutions of ammonia and carbon dioxide or ammonium carbonate and filtration, or only relatively small amounts of wash water or ammonium nitrate solutions are needed to adjust water and the ammonium nitrate contents of the invention.

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Overraskende indtræder der ved indføringen af et sådant calciumcarbonat i ammoniumnitratsmelten ikke nogen op-skumning, som forhindrer fremstillingen af den flydende blanding og det ved prilning eller granulering fremkomne 5 ammoniumnitrat- og calciumcarbonatindeholdende gødningsmiddel svarer i mekanisk og kemisk henseende til de stillede krav, dvs. det er slidstærkt og indeholder kun ringe mængder af tilbagedannet calciumnitrat. Fortrinsvis anvender man et calciumcarbonat, der har et ammoniumnitrat-10 indhold på 8 til 18 vægt-% og et vandindhold på 6 til 10 vægt-%.Surprisingly, upon introduction of such calcium carbonate into the ammonium nitrate melt, no foaming which prevents the preparation of the liquid mixture and the ammonium nitrate and calcium carbonate-containing fertilizer obtained by prilling or granulating, responds in mechanical and chemical respects, i.e. it is durable and contains only small amounts of recycled calcium nitrate. Preferably, a calcium carbonate having an ammonium nitrate-10 content of 8 to 18% by weight and a water content of 6 to 10% by weight is used.

Med henblik på fremstilling af gødningsmidlet går man på sædvanlig måde ud fra ammoniumnitratsmelter, der udviser 15 et indhold af NH^NOg på 95-99 vægt-%. I denne smelte indfører man det vand- og ammoniumnitratholdige calciumcarbonat, og den fremkomne flydende blanding, hvis temperatur hensigtsmæssigt andrager 140 til 150 eC, overføres derpå på i og for sig kendt måde f.eks. ved prilning el-20 ler granulering til den kornede form. Det er med henblik på at undgå en eventuelt endnu optrædende ringe skumning fordelagtigt yderligere at tilsætte uorganiske sulfater, såsom ammoniumsulfat, aluminiumsulfat, calciumsulfat, jernsulfat, kaliumsulfat og natriumsulfat i mængder ind-25 til 1,0 vægt-%, beregnet i forhold til den totale mængde af den flydende blanding. Denne tilsætning kan foretages før, under eller efter indarbejdningen af calciumcarbona-tet. I afhængighed af den ønskede sammensætning af produktet indfører man i ammoniumnitratsmelten 3 til 40 30 vægt-% calciumcarbonat (i hvert tilfælde beregnet i forhold til tørstoffet). De i de følgende eksempler angivne procentangivelser refererer til vægt-procenter, med mindre andet er angivet.For the preparation of the fertilizer, the ammonium nitrate melts, which have a content of NH 2 NOg of 95-99% by weight, are conventionally used. Into this melt is introduced the water and ammonium nitrate-containing calcium carbonate, and the resulting liquid mixture, whose temperature is suitably 140 to 150 eC, is then transferred in a manner known per se, e.g. by basting or granulating to the granular form. It is advantageous to further add inorganic sulphates such as ammonium sulphate, aluminum sulphate, calcium sulphate, iron sulphate, potassium sulphate and sodium sulphate in amounts of 25 to 1.0% by weight, in order to avoid any slight foaming which may still occur. total amount of the liquid mixture. This addition can be made before, during or after the incorporation of the calcium carbonate. Depending on the desired composition of the product, 3 to 40% by weight of calcium carbonate (in each case calculated relative to the dry matter) is introduced into the ammonium nitrate melt. The percentages given in the following examples refer to weight percentages unless otherwise indicated.

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4 EKSEMPEL 1EXAMPLE 1

Pr. time forarbejder man en 98 % ammoniumnitratsmelte, der indeholder 90 kg magnesiumsulfat, og 22 t calciumcar-5 bonat, der indeholder 8,2 % ammoniumnitrat og 7,4 % ^0, uden forstyrrende skumning til en flydende blanding med en temperatur af 140 °C. Denne flydende blanding bliver granuleret i en tromle og bliver derefter i de efterfølgende anlæg afkølet, sigtet og tilsat et antibagemiddel.Pr. An hourly 98% ammonium nitrate melt containing 90 kg of magnesium sulfate and 22 t of calcium carbonate containing 8.2% of ammonium nitrate and 7.4% of 0 are processed without interfering foaming to a liquid mixture at a temperature of 140 ° C. This liquid mixture is granulated in a drum and then cooled, screened and added to an antibacterial agent in the subsequent plants.

10 Færdigproduktet indeholde 27,50 % N og 0,2 % H20. Elek-tromikroskopiske optagelser af granulatbrudflader viser, at calciumcarbonatet er fast indlejret i ammoniumnitratet af granulatkornene med kraftig adhæsion.The finished product contains 27.50% N and 0.2% H2 O. Electromicroscopic recordings of granular fracture surfaces show that the calcium carbonate is firmly embedded in the ammonium nitrate of the granular granules with strong adhesion.

15 EKSEMPEL 2EXAMPLE 2

Pr. time forarbejdes 40,1 t af en 98,2 % ammoniumnitratsmelte, der indeholder 85 kg aluminiumsulfat, og 11,6 t med vand udvasket, filterfugtigt calciumcarbonat, der in- · 20 deholder 1,6 % ammoniumnitrat og 9,6 % H20, til en flydende blanding med en temperatur af 144 °C. Den flydende blanding bliver, som beskrevet i eksempel 1, granuleret, og granulatet bliver afkølet, sigtet og tilsat et antibagemiddel. Færdigproduktet indeholder 27,55 % N og 0,23 % 25 H20.Pr. per hour, 40.1 tonnes are processed from a 98.2% ammonium nitrate melt containing 85 kg of aluminum sulfate and 11.6 tonnes of water leached filter-moist calcium carbonate containing 1.6% ammonium nitrate and 9.6% H2 O; to a liquid mixture at a temperature of 144 ° C. The liquid mixture is granulated, as described in Example 1, and the granulate is cooled, sieved and added with an antibacterial agent. The finished product contains 27.55% N and 0.23% 25 H2 O.

EKSEMPEL 3EXAMPLE 3

Man forarbejder pr. time 20,2 t af en 97,6 % ammoniumni-30 tratsmelte og 1,1 t calciumcarbonat, der indeholder 17,6 % ammoniumnitrat og 7,1 % H20, til en flydende blanding med en temperatur af 145 °C. Denne flydende blanding granuleres på en roterende skive, og granulatet bliver derpå tørret, afkølet, sigtet og tilsat et antibagemiddel. Det 35 slidstærke færdigprodukt indeholder 33,5 % N og 0,25 % H2°.You process by per hour 20.2 t of a 97.6% ammonium nitrate melt and 1.1 t of calcium carbonate containing 17.6% ammonium nitrate and 7.1% H2 O, to a liquid mixture at a temperature of 145 ° C. This liquid mixture is granulated on a rotating disk and the granulate is then dried, cooled, sieved and added with an antibacterial agent. The 35 durable finished product contains 33.5% N and 0.25% H2 °.

Claims

A process for the preparation of ammonium nitrate and calcium carbonate-containing granular fertilizers by introducing calcium carbonate prepared by reaction of calcium nitrate with ammonia and carbon dioxide in aqueous solution into melts of ammonium nitrate and transferring the resulting liquid mixtures to the granular form, 10, characterized in that a calcium carbonate containing ammonium nitrate and water is used, with the proviso that the sum of the ammonium nitrate and water content does not exceed 25% by weight, the water content is 4 to 11% by weight, and the content of ammonium nitrate at least 15% by weight.

Process according to claim 1, characterized in that the water content is 6 to 10% by weight and the ammonium nitrate content is 8 to 18% by weight. 20

Process according to claims 1 and 2, characterized in that further inorganic sulfates are introduced into the melts. 25 30 35