WO2001098233A1 - Process for producing a ns-fertilizer - Google Patents
Process for producing a ns-fertilizer Download PDFInfo
- Publication number
- WO2001098233A1 WO2001098233A1 PCT/EP2000/005689 EP0005689W WO0198233A1 WO 2001098233 A1 WO2001098233 A1 WO 2001098233A1 EP 0005689 W EP0005689 W EP 0005689W WO 0198233 A1 WO0198233 A1 WO 0198233A1
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- Prior art keywords
- mixture
- weight
- free water
- process according
- water
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Classifications
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C1/00—Ammonium nitrate fertilisers
- C05C1/02—Granulation; Pelletisation; Stabilisation; Colouring
-
- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C1/00—Ammonium nitrate fertilisers
Definitions
- the invention relates to a process for preparing a fertilizer composition comprising an ammonium nitrate and calcium sulphate.
- a convenient way for adding sulphur to the soil is the introduction of S-containing N-fertilizers.
- fertilizers especially ammonium nitrate containing completely or partially dihydrated gypsum, which is applied as a coating to the fertilizer granules.
- the product is obtained in that completely or partially dihydrated gypsum is added to a granulator, which already contains an aqueous suspension of ammonium nitrate.
- dihydrate gypsum is cheap compared with anhydriate or hemihydrate gypsum and is readily available as a side stream numerous chemical processes in which it must be handled as a waste product, although its chemical composition and purity is of a sufficient quality to be used as an addition to ammonium nitrate. Pure mixing of ammonium nitrate granules with dihydrate gypsum has not been possible because of demixing during transport and storage, so that no efficient distribution of the gypsum can be obtained during the spreading of the fertilizer. It is therefor an object of the invention to provide a process of the type mentioned in the preamble allowing the use of dihydrate gypsum as a source of sulphur in the fertilizer.
- a first mixture is made comprising 50-75 % by weight of ammonium nitrate, 10-40 % by weight of dihydrate calcium sulphate and water in order to obtain a second mixture containing 5 - 25 % by weight of free water which is allowed to react at a temperature of 90 - 165 °C during at least 2 minutes in order to allow the dihydrate calcium sulphate to be converted into hemihydrate calcium sulphate and subsequently allowing the free water to be evaporated until a second mixture is obtained containing 1 ,5 - 8 % by weight free water.
- Dihydrate calcium sulphate or gypsum can, depending of temperature, partial vapour pressure of water in the drying medium (air or wet solution), pH etc., be converted to other crystal types.
- Dihydrate gypsum is converted in both environments to different types of hemihydrate (alfa or beta) and consequently to different types of anhydrous calciumsulphate when increasing temperature. In certain circumstances anhydrous calciumsulphate can be formed straight from dihydrate gypsum.
- the beta crystal types are formed when using air as drying medium, the alfa crystal types are formed when dihydrate gypsum is brought into an autoclave at elevated temperatures and pressures or when brought in acids.
- the different crystal types of CaSO 4 obtained behave very different when added to water (building industry), and certainly when brought into contact with hot solutions of AN melt.
- alfa hemihydrate crystals intermediate from phospho acid process
- straight in pug mill or drum granulation processes resulted in for the fluid bed process non viscous behaving slurry and gave for the drum and pug mill processes a stable granulation without scaling problems.
- This type of alfa hemi hydrate, obtained from the phospho acid process is however unstable and a lot of process steps are needed to obtain the purified hemihydrate (filtration, washing, drying, etc.).
- a first mixture is made comprising 50 - 70 % by weight of ammonium nitrate, 10 - 40 % by weight of dihydrate calcium sulphate and water in order to obtain a second mixture containing 5 - 25 % by weight of free water which is allowed to react at a temperature of 90 - 165 °C during at least 2 minutes in order to allow the dihydrate calciumsulphate to be converted into hemihydrate calcium sulphate and subsequently allowing the free water to be evaporated until a second mixture is obtained containing 1 ,5 - 8 % by weight free water.
- the water content of the second mixture is 2 - 4 % by weight of free water, and more preferably 2,5 - 3,5 % by weight of free water, which is the optimal slurry concentration for most of the granulation processes and at least for the Fluid Bed Granulation process.
- the viscosity of the second mixture is not higher than 400 centipoise, slurries with a higher viscosity will result in unstable process conditions such as lump formation, granules with a rough surface.
- the process is performed in such a way that the first reaction mixture has a pH not higher than 8 what leads also to a higher viscosity.
- the first mixture comprises 15 - 35 % by weight of dihydrate calcium sulphate and 10 - 25 % by weight of free water.
- the second mixture is allowed to react at a temperature of 100 - 120 °C.
- a temperature below 90 to 100 C the rate of the conversion reaction is getting too low and at higher temperature there is an increasing possibility of anhydrite formation and too close to the boiling point of the mixture (avoid pump cavitation)
- the dihydrate calciumsulphate particles In order to optimize the recrystallization, i.e. to obtain a reasonable conversion within acceptable time limits it is preferred that 90 % by weight of the dihydrate calciumsulphate particles have a size smaller than 150 ⁇ m.
- FIG. 1 illustrates a process route which can be applied for the process described in this invention.
- the main conversipn reaction to alfa hemihydrate takes place in a stirred reactor 1.
- a supply hopper and dosing system 2, 3 and transport system 4 such as a screw supplies the gypsum in the reactor, the ammonium nitrate mixed with water in a static mixer 6.
- the water should be supplied in such amount that the right ratio ammonium nitrate - water - dihydrate gypsum is obtained in the reactor vessel, in which the obtained slurry should be kept at the preferred residence time in order to promote maximum recrystallization to alfa hemihydrate and thus permit minimal viscosity increase.
- the homogeneous suspension can be withdrawn centrally form the bottom to the reactor and can be circulated over a heat exchanger 7 to keep the temperature of the reactor 1 in the preferred temperature range.
- the suspension can be withdrawn from the recirculation loop after the heat exchanger 7 and supplied to a vacuum evaporator 8 to evaporate the free water in the slurry until a mixture is obtained which should be directly compatible with the Hydro Fluid Bed Granulation Process or any other granulation process.
- Ammonium nitrate is brought in a four necked bottle, melted, and optionally the concentration can be adjusted to required levels. At different temperatures gypsum, with or without free moisture, is added.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Fertilizers (AREA)
Abstract
A process for preparing a fertiliser composition comprising an ammonium nitrate and calcium sulphate, wherein a first mixture is made comprising 50-70 % by weight of ammonium nitrate, 10-40 % by weight of dihydrate calcium sulphate and water in order to obtain a second mixture containing 5-25 % by weight of free water which is allowed to react at a temperature of 90-165 °C during at least 2 minutes in order to allow the dihydrate calcium sulphate to be converted into hemihydrate calcium sulphate, and subsequently allowing the free water to be evaporated until a second mixture is obtained containing 1,5-8 % by weight free water.
Description
Process for producing a NS-fertilizer
The invention relates to a process for preparing a fertilizer composition comprising an ammonium nitrate and calcium sulphate.
During the last decade there is a growing demand for sulphur containing fertilizer. As fossil fuels are more and more desulphurized, sulphur dioxide concentrations in rain have been decreased substantially. This reduction of sulphur in flue gas combined with increased SO2 abatement, has evolved to such an extent that deposits of sulphur on arable land are becoming too low for optimal plant growth.
Addition of sulphur has become essential to improve the efficiency of the fertilizer by increasing the nitrogen uptake by the crops.
A convenient way for adding sulphur to the soil is the introduction of S-containing N-fertilizers. In WO-A-9714665 there is described as fertilizers, especially ammonium nitrate containing completely or partially dihydrated gypsum, which is applied as a coating to the fertilizer granules. The product is obtained in that completely or partially dihydrated gypsum is added to a granulator, which already contains an aqueous suspension of ammonium nitrate.
It is also known to add hemihydrate gypsum prior to granulation to an ammonium nitrate melt. After granulation granules with entirely mixed ammonium nitrate and gypsum is obtained.
All these known processes use in fact completely or partially dihydrated gypsum. The use of dihydrate gypsum was not possible for the production of ammonium nitrate granules containing gypsum, and the production of this product was based upon the use of mixed anhydrite gypsum or especially prepared anhydriate or hemihydrate gypsum.
Otherwise dihydrate gypsum is cheap compared with anhydriate or hemihydrate gypsum and is readily available as a side stream numerous chemical processes in which it must be handled as a waste product, although its chemical composition and purity is of a sufficient quality to be used as an addition to ammonium nitrate. Pure mixing of ammonium nitrate granules with dihydrate gypsum has not been possible because of demixing during transport and storage, so that no efficient distribution of the gypsum can be obtained during the spreading of the fertilizer.
It is therefor an object of the invention to provide a process of the type mentioned in the preamble allowing the use of dihydrate gypsum as a source of sulphur in the fertilizer.
This and other objects are obtained in that a first mixture is made comprising 50-75 % by weight of ammonium nitrate, 10-40 % by weight of dihydrate calcium sulphate and water in order to obtain a second mixture containing 5 - 25 % by weight of free water which is allowed to react at a temperature of 90 - 165 °C during at least 2 minutes in order to allow the dihydrate calcium sulphate to be converted into hemihydrate calcium sulphate and subsequently allowing the free water to be evaporated until a second mixture is obtained containing 1 ,5 - 8 % by weight free water.
In this way it becomes possible to obtain a mixture which can be further supplied to the traditional granulation processes, such as fluid bed, drum or pug mill processes and can be granulated without using extreme process conditions.
Although the process as such is not completely understood, the following may be accepted as a possible explanation of the process.
Dihydrate calcium sulphate or gypsum can, depending of temperature, partial vapour pressure of water in the drying medium (air or wet solution), pH etc., be converted to other crystal types. Dihydrate gypsum is converted in both environments to different types of hemihydrate (alfa or beta) and consequently to different types of anhydrous calciumsulphate when increasing temperature. In certain circumstances anhydrous calciumsulphate can be formed straight from dihydrate gypsum. The beta crystal types are formed when using air as drying medium, the alfa crystal types are formed when dihydrate gypsum is brought into an autoclave at elevated temperatures and pressures or when brought in acids. The different crystal types of CaSO4 obtained, behave very different when added to water (building industry), and certainly when brought into contact with hot solutions of AN melt.
Laboratory and pilot tests had proven the following :
- bringing DH gypsum crystals with or without free moisture, straight in a pug mill or drum granulator, end up with an unstable granulation : the free water and the at elevated temperature released crystal water makes the granulation to wet, and makes it necessary to evaporate huge amounts of water in the granulator and dryer which has a dramatically impact on its capacity.
- bringing DH gypsum crystals, with or without free moisture, in a concentrated ammonium nitrate melt, which is necessary for fluid bed granulation processes, results, although the water content of the slurry has increased, in a high viscous mixture. This makes pumping and the necessary evaporation of the, at higher tempera- ture released crystal water impossible.
- bringing air dried calcium sulphate crystals (or beta hemihydrate (plaster); beta-anhy- drates or mixtures of both) straight in a pug mill or drum granulation process results in scaling in the granulator. When adding these calcium sulphates to a concentrated AN melt, the resulting slurry behaves again to viscous for further processing. Another disadvantage for these calciumsulphate sources is the high energy cost, when applying hot air, to remove the water from dihydrate to beta hemi or beta anhydrate.
- bringing alfa hemihydrate crystals (intermediate from phospho acid process) into concentrated melt, necessary for fluid bed granulation, or straight in pug mill or drum granulation processes resulted in for the fluid bed process non viscous behaving slurry and gave for the drum and pug mill processes a stable granulation without scaling problems. This type of alfa hemi hydrate, obtained from the phospho acid process, is however unstable and a lot of process steps are needed to obtain the purified hemihydrate (filtration, washing, drying, etc.).
- Supprisingly we have found a process route to obtain similar alfa hemihydrate crystals from DH crystals making use of the AN environment. DH gypsum can be recristallized in a fast way in AN solution at the right conditions of concentration-temperature- residence time - pH. The obtained crystal phase has a stability which makes it possible to evaporate excess of water without scaling problems, without further crystal modifications nor viscosity increase. This process has several advantages compared to other processes :
- no elevated pressures need to be applied, no need for an expensive autoclave
- alfa hemihydrate as intermediate in the phosphoric acid industry or alfa hemihydrate production by dispersing DH in aqueous sulphuric acid makes filtration, washing and consequently neutralisation necessary to apply the obtained hemi- hydrate in AN environment.
- after recrystallization the gypsum does not need to be separated from a brine and no impurities need to be washed out since the fertilizer need to contain as well the dehydratating medium AN and alfahemihydrate.
The process according to the invention is characterized in that a first mixture is made comprising 50 - 70 % by weight of ammonium nitrate, 10 - 40 % by weight of dihydrate calcium sulphate and water in order to obtain a second mixture containing 5 - 25 % by weight of free water which is allowed to react at a temperature of 90 - 165 °C during at least 2 minutes in order to allow the dihydrate calciumsulphate to be converted into hemihydrate calcium sulphate and subsequently allowing the free water to be evaporated until a second mixture is obtained containing 1 ,5 - 8 % by weight free water.
In this way, it was possible to have a mixture which can be handled in the normal granulation processes and containing the required amounts of calciumsulphate.
Preferably the water content of the second mixture is 2 - 4 % by weight of free water, and more preferably 2,5 - 3,5 % by weight of free water, which is the optimal slurry concentration for most of the granulation processes and at least for the Fluid Bed Granulation process. In a preferred embodiment of the process according to the invention the viscosity of the second mixture is not higher than 400 centipoise, slurries with a higher viscosity will result in unstable process conditions such as lump formation, granules with a rough surface.
Furthermore the process is performed in such a way that the first reaction mixture has a pH not higher than 8 what leads also to a higher viscosity.
In order to convert completely the gypsum to the desired crystal form and to optain the right composition of the NS fertilizer and to minimize the amount of water to evaporate the first mixture comprises 15 - 35 % by weight of dihydrate calcium sulphate and 10 - 25 % by weight of free water.
In another preferred embodiment of the process according to the invention the second mixture is allowed to react at a temperature of 100 - 120 °C. At a temperature below 90 to 100 C the rate of the conversion reaction is getting too low and at higher temperature there is an increasing possibility of anhydrite formation and too close to the boiling point of the mixture (avoid pump cavitation)
In order to optimize the recrystallization, i.e. to obtain a reasonable conversion within acceptable time limits it is preferred that 90 % by weight of the dihydrate calciumsulphate particles have a size smaller than 150 μm.
The continuous process will now be described with annexed Figure 1 , which illustrates a process route which can be applied for the process described in this invention.
The main conversipn reaction to alfa hemihydrate takes place in a stirred reactor 1. A supply hopper and dosing system 2, 3 and transport system 4 such as a screw supplies the gypsum in the reactor, the ammonium nitrate mixed with water in a static mixer 6. The water should be supplied in such amount that the right ratio ammonium nitrate - water - dihydrate gypsum is obtained in the reactor vessel, in which the obtained slurry should be kept at the preferred residence time in order to promote maximum recrystallization to alfa hemihydrate and thus permit minimal viscosity increase.
The homogeneous suspension can be withdrawn centrally form the bottom to the reactor and can be circulated over a heat exchanger 7 to keep the temperature of the reactor 1 in the preferred temperature range.
The suspension can be withdrawn from the recirculation loop after the heat exchanger 7 and supplied to a vacuum evaporator 8 to evaporate the free water in the slurry until a mixture is obtained which should be directly compatible with the Hydro Fluid Bed Granulation Process or any other granulation process.
In order to further eludicate the process according to the invention a number of experiments have been performed which are described in more detail in the following examples.
Example 1.
Ammonium nitrate is brought in a four necked bottle, melted, and optionally the concentration can be adjusted to required levels. At different temperatures gypsum, with or without free moisture, is added.
When recrystallization to hemihydrate takes place the crystal water is set free, the hemihydrate crystals were determined with differential scanning calorimetry. For evaluation of the tests the ammonium nitrate to water ratio after and before conversion of the dihydrate to hemihydrate has been determined and are shown in table 1.
Table t
The recrystallization of different calciumsulphate sources in a high concentrated Ammonium nitrate melt into viscous behaving crystal structures results in a unpumpable suspension with a very high viscosity is illustrated by table 2. The suspensions were preparated according to the described test set up.
Table 2.
In an apparatus as described above, 255 kg of a 95 % ammonium nitrate melt, 8 kg water and 138 kg phospho-gypsum originated from Palfos phosphate rock was mixed in the reactor. The melt was heated and kept at a temperature of 120 °C. After 5 minutes the obtained suspension containing 15.15 % by weight of free water was concentrated until a mixture was obtained containing 3.5 % by weight of free water.
Process conditions :
Free water of the phospho-gypsum : 15.6 % Reactor - Temperature of the suspension in the reactor : 120 °C
- Free water of the suspension : 15.15 % Evaporator
- Feed : flow : 500 kg/hr temperature : 121 °C
- steam pressure : 8 bar
- vacuum separator : -0.2 bar
- temperature melt outlet separator : 155.5 °C Melt after evaporation
- temperature : 155 °C - free water : 3.5 %
- viscosity : 155 cp.
Example 3.
The influence of pH in the reactor and evaporation have been checked.
In an apparatus as described above, 285 kg of a 95 % ammonium nitrate melt, 8 kg water and 128 kg phospho-gypsum originated from Palfos phosphate rock was mixed in the reactor. After the addtion of NaOH to adjust tho pH to 7.5 the melt was heated and kept at a temperature of 120 °C. After 5 minutes the obtained suspension containing 14.7 % by weight of free water was concentrated until a mixture was obtained containing 3.5 % by weight of free water.
Process conditions :
Free water of the phospho-gypsum : 15.6 % Reactor
- Temperature of the suspension in the reactor : 120 °C - Free water : 14.7 %
Evaporator
- Feed : flow : 500 kg/hr temperature : 118 °C pH : 7.5 - steam pressure : 8 bar
- vacuum separator : -0.2 bar
- temperature melt outlet separator : 153 °C Melt after evaporation
- temperature : 153 °C - free water : 3.5 %
- viscosity : 660 cp.
From this test it becomes clear that the pH of the slurry in the reactor has a negative influence on the viscosity of the obtained mixture after evaporation.
Example 4.
A 150 kg, mixture obtained in example 1 , additional dolomite and a few ppm granulation additive at 160 °C. This melt is sprayed on seed material in a batch fluid bed granulator at a bed temperature of approximately 130 °C. After granulation the product is cooled to 35 °C. The desired amount of Nitrogen in the end product determines the amount of dolomite which is added.
Characteristics of the end product :
Claims
1. A process for preparing a fertiliser composition comprising an ammonium nitrate and calcium sulphate, characterized in that a first mixture is made comprising 50 - 70 % by weight of ammonium nitrate, 10 - 40 % by weight of dihydrate calcium sulphate and water in order to obtain a second mixture containing 5 - 25 % by weight of free water which is allowed to react at a temperature of 90 - 165 °C during at least 2 minutes in order to allow the dihydrate calcium sulphate to be converted into hemihydrate calcium sulphate, and subsequently allowing the free water to be evaporated until a second mixture is obtained containing 1 ,5 - 8 % by weight free water.
2. A process according to claim 1 characterized in that the second mixture contains 2 - 4 % by weight free water.
3. A process according to claim 2, characterized in that the second mixture contains 2,5 - 3,5 % by weight free water.
4. A process according to any one of the preceding claims, characterized in that the visco- sity of the second mixture is not higher than 400 centipoise.
5. A process according to any of the preceding claims, characterized in that the first reaction mixture has a pH between 2 and 8.
6. A process according to any of the preceding claims, characterized in that the first mixture comprises 15 - 35 % by weight of dihydrate calcium sulphate and 10 - 25 % by weight water.
7. A process according to any one of the preceding claims characterized in that the second mixture is allowed to react at a temperature of 100 - 120 °C.
8. A process according to any one of the preceding claims, characterized in that 90 % of the dihydrate calciumsulphate particles have a size smaller than 150 μm.
9. A process according to any one of the preceding claims, characterized in that the second mixture is allowed to react during at least 5 minutes. A process according to any one of the preceding claims, characterized in that the second mixture is granulated and before, during or after the granulation it is mixed with additives.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/EP2000/005689 WO2001098233A1 (en) | 2000-06-20 | 2000-06-20 | Process for producing a ns-fertilizer |
| AU2000259759A AU2000259759A1 (en) | 2000-06-20 | 2000-06-20 | Process for producing a ns-fertilizer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/EP2000/005689 WO2001098233A1 (en) | 2000-06-20 | 2000-06-20 | Process for producing a ns-fertilizer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2001098233A1 true WO2001098233A1 (en) | 2001-12-27 |
Family
ID=8163998
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP2000/005689 WO2001098233A1 (en) | 2000-06-20 | 2000-06-20 | Process for producing a ns-fertilizer |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU2000259759A1 (en) |
| WO (1) | WO2001098233A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004055648A1 (en) * | 2004-11-12 | 2006-05-18 | Ami-Agrolinz Melamine International Gmbh | Process and apparatus for obtaining sulfur-containing nitrogen fertilizer |
| WO2006090007A3 (en) * | 2005-02-25 | 2007-05-24 | Kemira Growhow Oyj | Ammonium nitrate granule and method for the preperation of the same |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB800208A (en) * | 1955-04-01 | 1958-08-20 | Fisons Ltd | Granular products |
| GB877411A (en) * | 1957-04-18 | 1961-09-13 | Chemical Constuction G B Ltd | Improvements in or relating to the production of an ammonium nitrate fertiliser composition |
| DE3241443A1 (en) * | 1981-11-12 | 1983-05-19 | Basf Ag, 6700 Ludwigshafen | Method of manufacturing ammonium nitrate granules |
| GB2237800A (en) * | 1989-11-11 | 1991-05-15 | Willett & Son | Fertilizer particle and method of preparation |
| IT1249055B (en) * | 1991-05-22 | 1995-02-11 | Enichem Agricoltura Spa | Process for the production of a simple nitrogenous fertilizer called ammonium nitrate |
-
2000
- 2000-06-20 WO PCT/EP2000/005689 patent/WO2001098233A1/en active Application Filing
- 2000-06-20 AU AU2000259759A patent/AU2000259759A1/en not_active Abandoned
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB800208A (en) * | 1955-04-01 | 1958-08-20 | Fisons Ltd | Granular products |
| GB877411A (en) * | 1957-04-18 | 1961-09-13 | Chemical Constuction G B Ltd | Improvements in or relating to the production of an ammonium nitrate fertiliser composition |
| DE3241443A1 (en) * | 1981-11-12 | 1983-05-19 | Basf Ag, 6700 Ludwigshafen | Method of manufacturing ammonium nitrate granules |
| GB2237800A (en) * | 1989-11-11 | 1991-05-15 | Willett & Son | Fertilizer particle and method of preparation |
| IT1249055B (en) * | 1991-05-22 | 1995-02-11 | Enichem Agricoltura Spa | Process for the production of a simple nitrogenous fertilizer called ammonium nitrate |
Non-Patent Citations (1)
| Title |
|---|
| DATABASE EPODOC EUROPEAN PATENT OFFICE, THE HAGUE, NL; XP002159312 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004055648A1 (en) * | 2004-11-12 | 2006-05-18 | Ami-Agrolinz Melamine International Gmbh | Process and apparatus for obtaining sulfur-containing nitrogen fertilizer |
| WO2006090007A3 (en) * | 2005-02-25 | 2007-05-24 | Kemira Growhow Oyj | Ammonium nitrate granule and method for the preperation of the same |
| US8110018B2 (en) | 2005-02-25 | 2012-02-07 | Kemira Growhow Oyj | Ammonium nitrate granule and method for the preparation of the same |
Also Published As
| Publication number | Publication date |
|---|---|
| AU2000259759A1 (en) | 2002-01-02 |
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