AMMONIUM SULFATE-CONTAINING GRANULATE, METHOD, AND SYSTEM FOR PRODUCING SAME

Abstract

An ammonium-sulphate-containing fertiliser granulate including at least one metal salt as a granulation additive, which is a trace element and/or a granulation aid, and a sulphate of a metal selected from the group including Cu, Co, and Mo. A method is disclosed for the production of a fertiliser granulate in which the fertiliser granulate is produced by granulation in a fluidised-bed granulator, in which an aqueous composition containing at least the ammonium sulphate and at least one granulation additive is sprayed onto a fluidised bed of fluidised ammonium-sulphate-containing nuclei. Moreover, the granulation aid can contain at least one metal sulphate selected from the group comprising zinc sulphate, magnesium sulphate, manganese sulphate, iron sulphate or aluminium sulphate.

Claims

1.-18. (canceled)

19. An ammonium-sulphate-containing fertiliser granulate, comprising: at least one metal salt granulation additive; and wherein the granulate contains a granulation additive in the form of a sulphate of a metal selected from the group comprising Cu, Co, and Mo.

20. The ammonium-sulphate-containing fertiliser granulate of claim 19, wherein the granulate contains the granulation additive in an amount customary for trace elements.

21. The ammonium-sulphate-containing fertiliser granulate of claim 20, wherein the amount is in the ppm range.

22. The ammonium-sulphate-containing fertiliser granulate of claim 19, wherein the granulate contains CuSO.sub.4.5H.sub.2O as a trace element.

23. The ammonium-sulphate-containing fertiliser granulate of claim 19, wherein the granulate further comprises elemental sulphur and/or a calcium salt.

24. The ammonium-sulphate-containing fertiliser granulate of claim 23, wherein the elemental sulphur and/or the calcium salt are contained as finely-ground solid.

25. The ammonium-sulphate-containing fertiliser granulate of claim 19, wherein the granulate further contains at least one metal sulphate selected from the group comprising zinc sulphate, magnesium sulphate, manganese sulphate, iron sulphate or aluminium sulphate as a granulation aid.

26. The ammonium-sulphate-containing fertiliser granulate of claim 19, wherein the granulation additive is contained in the granulate in an amount of 0.5 to 2.5% by weight.

27. The ammonium-sulphate-containing fertiliser granulate of claim 26, wherein the metal sulphate is contained in the granulate in an amount of 0.5 to 2.5% by weight.

28. A method for the production of a fertiliser granulate, comprising: granulating the fertiliser granulate in a fluidised-bed granulator, in which an aqueous composition containing at least ammonium sulphate and at least one granulation additive and/or trace element and/or granulation aid is sprayed onto a fluidised bed of fluidised ammonium-sulphate-containing nuclei, wherein the granulation additive contains a sulphate of a metal selected from the group comprising Cu, Co, and Mo and/or the granulation aid contains at least one metal sulphate selected from the group comprising zinc sulphate, magnesium sulphate, manganese sulphate, iron sulphate or aluminium sulphate.

29. The method for the production of a fertiliser granulate of claim 28, wherein the granulation aid contains a mixture of iron sulphate and aluminium sulphate.

30. The method for the production of a fertiliser granulate of claim 29, wherein the granulation aid contains a mixture of iron sulphate and aluminium sulphate with an amount of 50% by weight or less of iron sulphate and an amount of 50% by weight or more of aluminium sulphate.

31. The method for the production of a fertiliser granulate of claim 28, wherein a first composition containing at least one granulation aid and/or granulation additive and/or trace element in an aqueous solution and a second composition containing ammonium sulphate in an aqueous solution are produced separately, wherein the first and second compositions are then mixed with each other and the mixture is sprayed in the fluidised-bed granulator.

32. The method for the production of a fertiliser granulate of claim 31, wherein water is further added to the mixture before spraying in the fluidised-bed granulator in order to arrive at a specified solution concentration.

33. The method for the production of a fertiliser granulate of claim 31, wherein ammonium sulphate is further added to the mixture as a solid before spraying in order to arrive at a specified solution concentration and a specified mixing ratio.

34. The method for the production of a fertiliser granulate of claim 28, wherein the aqueous composition is sprayed from below into a fluidised bed of the fluidised-bed granulator.

35. The method for the production of a fertiliser granulate of claim 28, wherein the aqueous composition is sprayed via nozzles at a spray rate of at least about 150 ml/min per nozzle.

36. The method for the production of a fertiliser granulate of claim 28, wherein the granulate is then dried in the fluidised-bed granulator in which it was produced.

37. The method for the production of a fertiliser granulate of claim 36, wherein the granulate is then dried in the fluidised-bed granulator in which it was produced with hot air.

38. A system for the production of a fertiliser granulate based on ammonium sulphate comprising: a fluidised-bed granulator to which process air is supplied via a line and to which a solution containing ammonium sulphate and granulation additives is supplied, the solution being sprayed into the fluidised bed granulator via a spray nozzle; wherein the system comprises: separate first and second vessels, wherein the first vessel is configured to receive a first solution containing granulation additives in water and the second vessel is configured to receive a solution containing ammonium sulphate in water, and wherein the first and second vessels are connected to each other or to a further vessel via a line and at least one of the first and second vessels or the further vessel is directly or indirectly operatively connected to the fluidised-bed granulator via a line.

Description

[0099] In the following, the present invention is explained in further detail by means of examples with reference to the attached drawing. The figures are as follows:

[0100] FIG. 1 is a flow chart of an exemplary granulation system that was used for the production of a fertiliser granulate according to the invention.

[0101] A possible example of the present invention is explained in further detail in the following with reference to FIG. 1. The FIGURE shows a flowchart of an exemplary granulation system that was used for the production of fertiliser granules according to the invention. This is a so-called fluidised-bed granulator 17. In this system, the air used for fluidisation is drawn from the environment, and it then flows via the line 18 and a distributor plate 2 into the process chamber 1. Before entering the process chamber, the air passes through an electric air heater 10. In the process chamber 1 is a spray nozzle 3 (an external mixing two-fluid nozzle with a cleaning needle), which is built-in in the bottom-spray configuration and sprays the solution vertically upward in parallel flow to the fluidisation air. The spray nozzle 3 is supplied via the line 20 with compressed air.

[0102] The spray solution is prepared batchwise in vessels 8. Granulation additives are dissolved in a first vessel 8a. The granulation additives are supplied to this first vessel 8a via a line 11. Water 12 is supplied to this first vessel 8a via a further line.

[0103] The ammonium sulphate solution is prepared in a second vessel 8b. On the one hand, water is supplied to this second vessel 8b via a branch line 13 connected to the line 12, and on the other, the ammonium sulphate (AS) is fed into the second vessel 8a via a further line 14. The corresponding amount of additive solution is metered from the first vessel 8a into the second vessel 8b together with the AS solution. The solution is homogenised using an agitator and preheated to the process temperature. The solution is then conveyed via a pump 5 through the line 19 into the fluidised-bed granulator 17. Above the process chamber 1 there is an expansion chamber 4 which has a larger device cross-section than the process chamber 1. The enlarged cross-section lowers the air speed and thus reduces the discharge of small particles from the system. The exhaust air is fed into an external purification stage 6 and is depleted of discharged particles there. A blower 7 is located downstream of the purification stage such that the entire system is operated in suction mode (negative pressure). The removed granulate is classified using a screening tower 9 into the 3 fractions of oversized particles (>4 mm), product (2-4 mm) and undersized particles (<2 mm). The screened-off undersized particles (fine particles) are recycled via the lines 15, 16 and fed into the granulator together with additional nucleus material.

[0104] The entire process is operated and monitored by means of a programmable logic controller (PLC). All relevant data are displayed on a PC in a real-time flowchart and stored with defined timing. Control of the fluidisation air flow and the air heater performance is carried out automatically, wherein the desired volume flow and supply air temperature are predetermined. The sprayed-in mass flow is controlled via the pump 5.

[0105] Examples Using Granulation Aids of Different Compositions:

[0106] Several definitions used in the present application are listed below.

[0107] Granule hardness: The hardness of the granules produced was measured using a Texture Analyser from Stable Micro Systems Ltd. For determination of granule hardness, in all cases, granules having a particle size between 2.5 and 2.8 mm that had been separated from the other samples by means of a screening unit were used. Granule hardness was determined from the recorded force displacement curve by means of a specified macro. In this context, granule hardness is defined as the maximum force [N] a particle can absorb before it breaks. In order to improve statistical certainty, at least 30 particles were measured for each sample selected for measurement of granule hardness. The mean value, standard deviation, and maximum and minimum values were then determined from the at least 30 measured values.

[0108] Particle size distribution: A so-called CAMSIZER XT from Retsch Technology, which is based on an optical method, was used for measurement of particle size distribution. The particles are conveyed via a channel into a free-fall device. The particles dispersed in this manner fall through the measuring plane, where they pass by two LED strobe light sources. The shadow projections of the granules are recorded by two digital cameras. The cameras differ in their resolution such that one camera records the smaller and one the larger particles. The raw data are automatically evaluated by software and the distribution times are calculated in real time.

[0109] Residual moisture determination: The residual moisture of all of the samples was determined. For this purpose, a weighed sample was stored overnight on a small dish at 100 C. in a drying oven, and the weight of the sample was again determined after drying. Using the following formula, the measured values can be used to calculate the residual moisture content (RF) in percent with respect to the wet sample. A double determination was carried out for each sample in every case.

RF[%]=m.sub.wetm.sub.dry/m.sub.wetm.sub.dish

[0110] Bulk density: The bulk density of each end product was determined. For this purpose, a beaker having a specified volume V.sub.0 was filled with the product, and the mass was determined. According to the following formula, the mass of the sample with respect to volume gives the bulk density of the sample.

.sub.bulk=m.sub.sample/V.sub.0

[0111] Substances used: The ammonium sulphate required for granulation was provided as a fine crystalline substance. A 40% by weight solution was produced with demineralised water.

[0112] All of the granulation aids were obtained from the firm Carl Roth GmbH+Co. KG.

[0113] In a series of tests, both trace elements as granulation additives composed of only one substance respectively, specifically copper sulphate pentahydrate, zinc sulphate heptahydrate and iron(II)sulphate heptahydrate, and combinations of iron sulphate and aluminium sulphate in which the aluminium sulphate was partially replaced in various amounts by iron sulphate were investigated. The additive contents are expressed with respect to sulphates free of water of crystallisation in all cases.

[0114] The test results are given in Table 1 below.

TABLE-US-00001 TABLE 1 Aluminium Aluminium Aluminium sulphate/iron sulphate/iron sulphate/iron Granulation Zinc Copper Iron sulphate sulphate sulphate aid sulphate sulphate sulphate 3:1 1:1 1:3 Spray 6 6 6 6 6 6 duration (h) Water 60 60 60 60 60 60 content in solution (%) Provided AS 5 5 5 5 5 5 (kg) Bed height 0.21 0.21 0.21 0.21 0.21 0.21 (m) Fluid air 215 215 215 215 215 215 stream (m.sup.3/h) Process <100 <100 <100 <100 <100 <100 temperature ( C.) Granule >20 >15 >25 >25 >20 >10 hardness (N) Residual <0.5 <0.5 <0.5 <0.5 <0.5 >1 moisture (%)

[0115] The granule hardness decreases with increasing iron sulphate content, which is particularly noticeable when the iron sulphate content is greater than 50%. For copper and zinc, the hardnesses were within an acceptable range.

[0116] In most cases, residual moisture was less than 0.5%.

LIST OF REFERENCE NOS

[0117] 1 Process chamber [0118] 2 Distributor plate [0119] 3 Spray nozzle [0120] 4 Expansion chamber [0121] 5 Pump [0122] 6 Purification stage [0123] 7 Blower [0124] 8a First vessel [0125] 8b Second vessel [0126] 9 Screening unit [0127] 10 Air heater [0128] 11 Line for addition of additives [0129] 12 Water supply line [0130] 13 Water supply line [0131] 14 Line for addition of ammonium sulphate [0132] 15 Line for recycling the fine particles [0133] 16 Line for recycling the fine particles [0134] 17 Granulator [0135] 18 Air line [0136] 19 Line for solution to the granulator [0137] 20 Compressed air line