Phase-stabilized ammonium nitrate explosives

Abstract

The present invention provides a phase-stabilized PSAN explosive containing ammonium nitrate (PSAN) pellets and a fuel. The PSAN pellets contain ammonium nitrate, potassium salt and an inorganic porosity enhancer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Australian provisional patent application 2020902693, entitled “PHASE-STABILIZED AMMONIUM NITRATE EXPLOSIVES”, filed on July 31, 2020, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to explosives. More particularly, the present disclosure relates to phase stabilized ammonium nitrate (PSAN) explosives. BRIEF DESCRIPTION OF THE DRAWINGS

[0004]

[0013] Embodiments disclosed herein will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings.

[0005] Figure 1 is a graph showing crush strength versus thermal cycling for ammonium nitrate fuel oil (ANFO) made with conventional ammonium nitrate (AN) pellets and ANFO made with exemplary PSAN pellets.

[0006] Figure 2 is a graph showing the temperature of PSAN pellets compared to conventional LDAN pellets while cycling in an oven.

[0007] Figure 3 is a graph showing the time required to heat PSAN pellets to 50°C compared to conventional LDAN pellets.

[0008] Figure 4 is a graph showing the time required to cool PSAN pellets from 50°C compared to conventional LDAN pellets.

[0009] Figure 5 is a graph showing the DSC of conventional LDAN pellets.

[0010] Figure 6 is a graph showing DSC of PSAN pellets. DETAILED DESCRIPTION

[0011] Phase stabilized ammonium nitrate (PSAN) explosives and related methods are disclosed herein. PSAN pellets containing an inorganic porosity enhancer such as aluminum sulfate have been found to be thermally stable, even in the presence of fuel.

[0012] Thermal cycling of ammonium nitrate (AN) above and below about 32°C results in crystalline phase changes. Thermal cycling of AN pellets results in expansion and contraction of the AN pellets and each associated crystalline phase change. Crystalline phase changes of AN also occur at other temperatures, as shown in Table 1.

[0013] Table 1: Crystalline phase of AN

[0014]

[0015] The expansion and contraction mechanisms of the AN pellets can negatively impact the integrity and / or stability of the AN pellets. For example, expansion and contraction can result in: i) weakening of the AN pellets; ii) increased AN fines formation (e.g., the AN pellets can break down); iii) increased brittleness of the AN pellets; and / or iv) increased moisture ingress into the AN pellets. These features or effects can result in agglomeration of the AN pellets, which can lead to processing and handling issues, loss of free-flowing behavior, and / or product rejection. This also applies to AN pellets mixed with liquid fuels, such as No. 2 fuel oil.

[0016] Any method disclosed herein includes one or more steps or operations for performing the method. The method steps and / or operations can be interchangeable with each other. In other words, unless the correct operation of the embodiment requires a specific step or operation sequence, the order and / or use of specific steps and / or operations can be modified. In addition, within the scope of the present disclosure, a subroutine or only a part of the method described herein can be a separate method. In other words, some methods can only include a part of the steps described in the more detailed method.

[0017] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, referenced phrases or variations thereof are not necessarily all referring to the same embodiment as described throughout this specification.

[0018] As reflected in the following claims, aspects of the invention lie in fewer combinations than all features of any single previously disclosed embodiment. Therefore, the claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim independently standing as a separate embodiment. This disclosure includes all permutations of independent claims and their dependent claims.

[0019] The recitation of the term "first" in a claim with respect to a feature or element does not necessarily imply the presence of second or additional such features or elements. It will be apparent to those skilled in the art that changes may be made to the details of the embodiments described herein without departing from the basic principles of the disclosure.

[0020] Compared to conventional or standard low-density ammonium nitrate (LDAN) pellet-based explosives, the PSAN explosives provided herein can exhibit a significantly increased effective storage period, for example, during the summer months when temperatures can often cycle above and below 32°C. Therefore, PSAN explosives can be shipped to or used in tropical regions and have a longer effective storage period than conventional LDAN ANFO. PSAN explosives can significantly reduce the health, safety and / or environmental risks associated with agglomerated and / or lumpy ANFO. PSAN explosives can eliminate the need for temperature-controlled storage infrastructure (e.g., ANFO storage sheds with air conditioning). PSAN explosives can increase the flexibility of ANFO supply plans to customers. PSAN explosives can reduce or eliminate product delivery bottlenecks. In addition, PSAN explosives can be used in multiple markets (e.g., Asia Pacific and North America).

[0021] PSAN explosives and methods of making PSAN pellets and explosives are disclosed herein. It will be readily appreciated that the components of the embodiments, as generally described below, may be arranged and designed in a variety of different configurations. Therefore, the following more detailed description of various embodiments, as described below and as illustrated in the accompanying drawings, is not intended to limit the scope of the present disclosure, but is merely representative of the various embodiments.

[0022] One aspect of the present disclosure relates to phase-stable ammonium nitrate (PSAN) explosives. The PSAN explosive may include PSAN pellets and fuel. In some embodiments, the PSAN pellets may contain potassium ions of potassium salts in an amount of 0.5 mole percent (mol%) to 5 mole percent based on the ammonium ions of ammonium nitrate. In multiple embodiments, the mole percent of potassium ions based on ammonium ions may be 2 mole percent to 5 mole percent, 2 mole percent to 4 mole percent, 2.1 mole percent to 4.0 mole percent, or about 3 mole percent. In contrast, conventional or standard low-density ammonium nitrate (LDAN) pellets or explosives based on LDAN pellets may refer to LDAN pellets or explosives based on LDAN pellets that lack potassium salts or ions. The PSAN pellets may be explosive grade. In certain embodiments, the PSAN pellets may be low density ("low density" pellets have a bulk density of 0.84 kg / L or less).

[0023] "Explosive grade" AN pellets have a minimum porosity of at least 5.7 FOR%. Explosive grade low density AN (LDAN) pellets are typically manufactured to include effective and ineffective porosity, such as by incorporating a suitable pore former into a concentrated ammonium nitrate solution prior to pelletization. Explosive grade pellets are typically manufactured to include effective and ineffective porosity that allows absorption of sufficient fuel oil so that the material can be effectively detonated. To determine whether the porosity is suitable for making an explosive, the ability of the pellet to absorb internal combustion engine fuel oil is used. A functional determination of porosity can be performed using a fuel oil retention test, in which a weighed amount of AN pellets is added to a weighed amount of fuel oil and mixed for a specified time. Excess fuel oil is removed using absorbent paper towels, the total mass of the ANFO product formed is recorded, and the percentage increase in mass is calculated. The porosity of the PSAN pellets, as determined by the fuel oil retention percentage (FOR%), can be 6 FOR% to 15 FOR%, 6 FOR% to 12 FOR%, or 5.5 FOR% to 9 FOR%. It is generally preferred that the porosity be such that the fuel oil absorption level is at least 5.7 FOR% to achieve an acceptable oxygen balance when sufficient fuel oil is added to the PSAN pellets to produce ANFO. Calculations of total porosity, including void porosity, can be determined in a suitable fluid medium.

[0024] The following method can be used to measure the FOR% associated with the porosity of pelletized ammonium nitrate. This method measures the increase in mass after a selected pellet sample is completely immersed in internal combustion fuel oil (DFO) and excess DFO is removed using a paper towel. This method can be used as a quality check for product raw material evaluation. First, 40g (±0.05g) of the AN pellet sample (fines removed) can be weighed into a labeled and tared 250ml screw-top sample jar. This is recorded as the "initial weight". Then 6.5ml of DFO can be added and the DFO can be evenly distributed over the sample. The lid is tightened and can be shaken vigorously for 30 seconds. The sample jar can then be placed on a bottle roller and the machine can be run at 40 rpm for 20 minutes. After 20 minutes, the jar can be tapped on the bench to remove pellets stuck to the lid. Two strips of absorbent paper can be placed: one loosely wrapped to fit the side of the jar; the other tightly wrapped and inserted into the center of the first strip of absorbent paper. The lid can be replaced and the jar can be shaken by hand for 3 minutes. The pellets should roll freely in the jar. The sample jar can be placed on a bottle roller and the machine run at 40 rpm for 15 minutes. The pellets should be evenly distributed along the length of the jar and the bottle roller can be adjusted to achieve this. The absorbent paper strip can then be carefully removed, ensuring that no pellets are removed from the jar. The pellets can be transferred to a tared 100 ml beaker and weighed to the nearest 0.05 g. This is recorded as the "final weight".

[0025] The fuel oil retention (FOR) percentage can be calculated as follows:

[0026] FOR (%) = ((final weight - initial weight) / final weight) x 100

[0027] The PSAN pellets also include an inorganic porosity enhancer. The inorganic porosity enhancer may include an interfacial surface modifier and / or a pore former. The interfacial surface modifier may also be a crystal habit modifier. Examples of inorganic porosity enhancers include aluminum sulfate (any of anhydrous or its hydrate form), iron sulfate, magnesium oxide, or any multivalent sulfate. The inorganic porosity enhancer may also include an additive. In certain embodiments, the inorganic porosity enhancer does not contain iron sulfate, magnesium oxide, or any compound. In certain embodiments, the inorganic porosity enhancer includes aluminum sulfate.

[0028] In certain embodiments, the concentration of the inorganic porosity enhancer can be 400 ppm to 4,000 ppm, e.g., 400 ppm to 1,000 ppm, 500 ppm to 900 ppm, 600 ppm to 800 ppm, or about 700 ppm, or, e.g., 2,000 ppm to 4,000 ppm, 2,500 ppm to 3,900 ppm, 3,000 ppm to 3,700 ppm, or about 3,500 ppm.

[0029] The potassium salt may be any potassium salt, such as at least one selected from potassium hydroxide, potassium nitrate, potassium sulfate, potassium bisulfate, potassium carbonate, and potassium bicarbonate. In some embodiments, potassium may be selected from at least one of potassium hydroxide, potassium nitrate, and potassium sulfate.

[0030] In some embodiments, the PSAN pellets may include 0.5 mol% to 5 mol% potassium ions of potassium hydroxide based on the ammonium ions of ammonium nitrate (corresponding to 0.4 wt% to 4 wt% potassium hydroxide based on the weight percentage (wt%) of ammonium nitrate). In various embodiments, the mole % of potassium ions based on ammonium ions may be 2 mol% to 5 mol% (about 1.5 wt% to 4 wt% potassium hydroxide), 2 mol% to 4 mol% (about 1.5 wt% to 3 wt% potassium hydroxide), 2.1 mol% to 4.0 mol% (about 1.5 wt% to 3 wt% potassium hydroxide), or about 3 mol% (about 2 wt% potassium hydroxide).

[0031] In certain embodiments, the PSAN pellets may include 0.5 mol% to 5 mol% potassium nitrate potassium ions based on the ammonium ions of the AN (1 wt% to 6 wt% potassium nitrate based on the AN). In various embodiments, the mole % of potassium ions based on the ammonium ions may be 2 mol% to 5 mol% (about 3 wt% to 6 wt% potassium nitrate), 2 mol% to 4 mol% (about 3 wt% to 5 wt% potassium nitrate), 2.1 mol% to 4.0 mol% (about 3 wt% to 5 wt% potassium nitrate), or about 3 mol% (about 4 wt% potassium nitrate).

[0032] In various embodiments, the PSAN pellets may include 0.5 mol% to 5 mol% potassium ions of potassium sulfate based on the ammonium ions of ammonium nitrate (1 wt% to 10 wt% potassium sulfate based on ammonium nitrate). In various embodiments, the mole % of potassium ions based on ammonium ions may be 2 mol% to 5 mol% (about 5 wt% to 10 wt% potassium sulfate), 2 mol% to 4 mol% (about 5 wt% to 8 wt% potassium sulfate), 2.1 mol% to 4.0 mol% (about 5 wt% to 8 wt% potassium sulfate), or about 3 mol% (about 6 wt% potassium sulfate).

[0033] In some embodiments, the bulk density of the PSAN pellets can be less than 0.9 kg / L. In addition, the PSAN pellets can be free of or substantially free of a crystalline phase change at 32°C. Alternatively, the crystalline phase change at 32°C can be shifted to a temperature greater than 50°C. The PSAN pellets can be free of or substantially free of a crystalline phase change at 84°C. Alternatively, the crystalline phase change at 84°C can be shifted to a temperature greater than 90°C or 95°C. In certain embodiments, the presence of a crystalline phase change at 32°C and / or a crystalline phase change at 84°C can be determined by thermal analysis and / or X-ray diffraction measurements. For example, thermal analysis can include differential scanning calorimetry analysis (DSC) and / or thermogravimetric analysis (TGA). "Substantially absent" a phase change at 32°C can correspond to sufficient elimination of a phase change so that the PSAN pellets can be thermally cycled 50 times and remain within customer specifications, such as those listed in Table 2.

[0034] In various embodiments, after thermally cycling the PSAN explosive 50 times, the thermally cycled PSAN explosive may have an average crush strength greater than 0.4 kg, such as 0.4 kg to 2.0 kg, 0.5 kg to 1.5 kg, 0.6 kg to 1.0 kg, or 0.7 kg to 0.9 kg. One cycle may include exposing the PSAN explosive to 15° C. for four hours and then to 45° C. for four hours.

[0035] In some embodiments, after thermally cycling the PSAN explosive 20 times ("test PSAN explosive"), the average crush strength of the thermally cycled PSAN explosive can be greater than the average crush strength of a control PSAN explosive that has not been thermally cycled. One cycle includes exposing the PSAN explosive to 15°C for four hours and then to 45°C for four hours. The test PSAN explosive and the control PSAN explosive comprise the same components; however, when the test PSAN explosive was subjected to thermal cycling, the control PSAN explosive was not subjected to thermal cycling.

[0036] The average crush strength of the thermally cycled PSAN explosive may be 5% to 100% greater than the average crush strength of the non-thermally cycled control PSAN explosive. In other embodiments, the average crush strength of the thermally cycled PSAN explosive may be 25% to 100% greater than the average crush strength of the non-thermally cycled control PSAN explosive. In certain embodiments, the average crush strength of the thermally cycled PSAN explosive may be 10% to 80%, 20% to 60%, or 25% to 40% greater than the average crush strength of the non-thermally cycled control PSAN explosive. And in other embodiments, the average crush strength of the thermally cycled PSAN explosive may be 35% to 90%, 45% to 80%, or 55% to 70% greater than the average crush strength of the non-thermally cycled control PSAN explosive. Therefore, thermal cycling can be used to increase the hardness of the PSAN explosive.

[0037] The crushing strength can be determined by the following method. All equipment including gloves should be dry and the samples should be sealed in airtight containers when stored. The sample is prepared by first weighing 250g of the ANFO final product sample and transferring it to the top of a sieve stack consisting of a 2.36mm sieve, a 2.00mm sieve and a collecting tray. The sample and sieve stack are placed in a sieve oscillator and oscillated for 10 minutes at an amplitude setting of 60. Fine particles in the receiving tray and oversized particles in the 2.36mm sieve are discarded. A small portion of the sample is taken out of the 2.00mm sieve for the crushing test. For the crushing test, 20 individual ANFO particles (AN pellets + fuel oil) are randomly selected from the 2.00mm sieve. The crushing test device is used to record KgF units, and the crushing test device includes a dynamometer (such as model M5-5) and a test stand (such as an electric test stand ESM301L). The particles are placed in the center of the test stand. The dynamometer is zeroed. The dynamometer piston is lowered to crush the test particle. After the dynamometer is fully extended, the applied force is recorded as the crush resistance. This process is performed for each of the 20 particles. The crush resistance is calculated as the average crush resistance of the 20 particles.

[0038] The effective storage period of the PSAN explosives as provided herein can be at least six months. For example, the PSAN explosives can have an effective storage period of up to six months or longer (such as at least two months, at least four months, or at least six months) when stored during a hot summer with an average daytime ambient temperature of 30°C to 50°C and an average nighttime temperature of 10°C to 30°C. In contrast, the effective storage period of conventional LDAN ANFO is much shorter without the aid of temperature control storage.

[0039] The PSAN pellets of the PSAN explosive may have tighter and more uniform crystal domains than the crystal domains of explosive grade ammonium nitrate pellets that do not contain potassium. Without wishing to be bound by theory, the tighter crystal domains of the PSAN pellets may contribute to increased hardness of the PSAN pellets compared to conventional LDAN pellets. Without wishing to be bound by theory, it is believed that the combination of potassium and a porosity enhancer may contribute to tighter and more uniform crystal domains of the PSAN pellets. Thus, the combination of potassium and a porosity enhancer may contribute to an unexpected increase in the crushing strength of the PSAN pellets while maintaining the porosity and low density of the pellets. The crystal domains may be determined by scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS).

[0040] The potassium of the PSAN pellet can be uniformly distributed throughout the pellet. When the PSAN pellet comprises an interfacial surface modifier (such as a portion of a polymer) comprising an alkyl group, the carbon of the PSAN pellet can be uniformly distributed throughout the pellet.

[0041] Examples of fuels that can be used with PSAN pellets include, but are not limited to, liquid fuels (such as fuel oil, diesel, distillate, furnace oil, kerosene, gasoline, and naphtha); waxes (such as microcrystalline wax, paraffin wax, and oil-containing wax); oils (such as paraffin oil, benzene, toluene, and xylene oils, asphalt materials, polymer oils (such as low molecular weight polymers of olefins), animal oils (such as fish oils) and other mineral oils, hydrocarbon oils, or fatty oils); and mixtures thereof. Any fuel commonly used for or with ANFO can be used.

[0042] The weight ratio of PSAN pellets to fuel can be, for example, 80:20 to 97:3, 85:15 to 96:4, 90:10 to 95:5, or 94:6. In certain embodiments, the fuel is not an ammonium nitrate emulsion, but is a fuel commonly used for conventional ANFO.

[0043] Any combination of components described with reference to the PSAN pellets or PSAN explosives as provided above, and their amounts or concentrations, may also be incorporated into the method of preparing the PSAN pellets or PSAN explosives. In addition, any of the characteristics or measurements of the PSAN pellets or PSAN explosives as provided above (e.g., bulk density, average crushing strength, and effective storage life) may also be applicable to the PSAN pellets or PSAN explosives prepared by the disclosed method.

[0044] Another aspect of the present disclosure relates to a method of increasing the hardness (e.g., average crush strength) of a PSAN explosive. In addition, any of the characteristics or measurements of the PSAN explosive as provided above may also be applicable to a PSAN explosive prepared by the method of increasing the hardness of a PSAN explosive. The method may include providing a PSAN pellet as discussed above and thermally cycling the PSAN pellet multiple times (e.g., at least 10 times or at least 20 times). After cycling, the average crush strength of the thermally cycled PSAN explosive may be greater than the average crush strength of a control PSAN explosive that has not been thermally cycled. One cycle may include exposing the PSAN explosive to 15°C for four hours and then exposing it to 45°C for four hours.

[0045] Another aspect of the present disclosure relates to a method of preparing PSAN pellets and / or PSAN explosives. The method may include forming a PSAN solution comprising a potassium salt and ammonium nitrate and crystallizing the PSAN solution to form the PSAN pellets. The PSAN pellets may be explosive grade and low density. The method may also include combining a porosity enhancer (e.g., aluminum sulfate) with the PSAN solution. Forming the PSAN solution may include mixing the potassium salt (solution) with water (or process condensate) and reacting the mixture with nitric acid and ammonia to form the PSAN solution, such as in a neutralizer.

[0046] In some embodiments, the use of a PSAN solution comprising potassium salt and ammonium nitrate provides manufacturing advantages in forming PSAN pellets compared to conventional AN solutions used to form conventional LDAN pellets without potassium salt. These manufacturing advantages can provide opportunities to eliminate bottlenecks in the facility manufacturing process. For example, conventional LDAN pellet manufacturing typically requires a reduction in pelletizing rates during hotter and more humid months to ensure that pellets are formed within appropriate specifications due to i) the pellet temperature observed at the bottom of the pelletizing tower and / or ii) the pellet temperature observed upon exiting a cooling mechanism (e.g., a fluidized bed cooler). The PSAN solutions disclosed herein do not require such a reduction in pelletizing rates.

[0047] In the process of crystallizing the PSAN solution to form PSAN pellets, droplets of the pellet solution fall into the prilling tower. As the droplets fall, they cool and solidify to form individual pellets. After further drying in the pre-dryer and drying drum, and screening to remove oversized and undersized materials, the pellets are then transferred to a cooling mechanism (such as a fluidized bed cooler) for further cooling, after which the pellets can be further processed (e.g., coated), stored and / or packaged. Typically, the temperature limit for conventional LDAN pellets when they reach the bottom of the prilling tower is 78°C to 82°C. This temperature limit ensures that conventional LDAN pellets complete the crystal phase transition from Phase II to Phase III at about 84°C before reaching the bottom of the prilling tower. At the bottom of the prilling tower, conventional LDAN pellets may still undergo phase transitions above this temperature limit, leading to agglomeration / agglomeration and / or other problems downstream of the manufacturing process. Furthermore, having conventional LDAN pellets above this temperature limit at the bottom of the pelletizing tower is a common problem during pellet manufacturing, especially in hot and humid environments (eg, environments with an ambient temperature of 35°C to 45°C).

[0048] It is generally required that the temperature of conventional LDAN pellets leaving a cooling mechanism (e.g., a fluidized bed cooler) be below 30°C. This temperature ensures that the conventional LDAN pellets complete the crystal phase transition from Phase III to Phase IV at about 32°C before a coating (e.g., an anti-caking coating) is applied. Conventional LDAN pellets leaving a cooling mechanism (e.g., a fluidized bed cooler) above this temperature may still undergo a phase transition, resulting in agglomeration / agglomeration and / or additional loss of free flow of the pellets in the silo or post-coating drum. This may further lead to problems when attempting to remove the pellets from the silo or post-coating drum and place them in a shipping container, bulk dump truck, etc. Exposing conventional LDAN pellets leaving a cooling mechanism (e.g., a fluidized bed cooler) above this temperature is a common problem in the pellet manufacturing process, especially in hot and humid environments (e.g., environments with ambient temperatures of 35°C to 45°C). In order to solve these problems, conventional manufacturing technology reduces the granulation rate from a maximum of about 40 T / hr (tons / hour) to less than 35 T / hr, less than 33 T / hr, less than 30 T / hr or less than 27 T / hr, especially in a hot and humid environment (e.g., an environment with an ambient temperature of 35° C. to 45° C.). In other words, conventional manufacturing technology reduces the granulation rate to between 25 T / hr and 35 T / hr, or between 25 T / hr and 30 T / hr, especially in a hot and humid environment (e.g., an environment with an ambient temperature of 35° C. to 45° C.). In other words, conventional manufacturing techniques reduce the granulation rate from 100% of the designed maximum granulation rate to a granulation rate of less than 90% of the designed maximum granulation rate, less than 80% of the designed maximum granulation rate, or less than 70% of the designed maximum granulation rate, or to a granulation rate between 60% and 90% of the designed maximum granulation rate, between 60% and 80% of the designed maximum granulation rate, or between 60% and 70% of the designed maximum granulation rate, especially in a hot and humid environment (e.g., an environment with an ambient temperature of 35° C. to 45° C.).

[0049] The use of the PSAN solution disclosed herein can achieve higher granulation rates in hot and humid environments. As described above, the phase transition at 32°C is minimized and / or eliminated, and the phase transition at 84°C is shifted to a higher temperature by the PSAN solution disclosed herein. For example, the phase transition at 84°C can be shifted (or increased) by about 5°C to about 25°C or about 10°C to about 20°C. In certain embodiments, the phase at 84°C is shifted to 95°C to 105°C.

[0050] Since the phase transition temperature of 84°C has been increased, the temperature limit at the bottom of the prilling tower can also be increased without causing manufacturing problems. For example, at the bottom of the prilling tower, the temperature limit of the PSAN pellets can be increased to at least 85°C, at least 86°C, at least 87°C, at least 88°C, at least 89°C, or at least 90°C, even in a hot and humid environment (e.g., an environment with an ambient temperature of 35°C to 45°C). In other words, at the bottom of the prilling tower, the upper temperature limit of the PSAN pellets can be increased to 85°C to 95°C or 85°C to 90°C, even in a hot and humid environment (e.g., an environment with an ambient temperature of 35°C to 45°C).

[0051] With the 32°C phase transition minimized and / or eliminated, there is little or no 32°C phase transition for the PSAN pellets after exiting the cooling mechanism (e.g., fluidized bed cooler) and / or during the coating process. Thus, the temperature limit of the PSAN pellets exiting the cooling mechanism (e.g., fluidized bed cooler) can be increased. In some embodiments, the temperature limit is increased to at least 35°C, at least 36°C, at least 37°C, at least 38°C, at least 39°C, or at least 40°C, even in hot and humid environments (e.g., environments with an ambient temperature of 35°C to 45°C). In other words, the temperature limit is increased to between 30°C and 40°C, between 32°C and 40°C, or between 35°C and 40°C, even in hot and humid environments (e.g., environments with an ambient temperature of 35°C to 45°C). In addition, as the 32°C phase change is minimized and / or eliminated, the PSAN pellets also leave the cooling mechanism (e.g., fluidized bed cooler) at a lower temperature than conventional LDAN because the PSAN pellets release less thermal energy due to the lack of phase change. For example, in some embodiments, the temperature of the PSAN pellets leaving the cooling mechanism (e.g., fluidized bed cooler) is 2°C to 5°C or 3°C to 4°C lower than conventional LDAN under the same manufacturing conditions, even in a hot and humid environment (e.g., an environment with an ambient temperature of 35°C to 45°C).

[0052] One or more of i) the temperature limit of the PSAN pellets at the bottom of the prilling tower and ii) the minimized phase change temperature of 32° C. also enables the manufacturing process to maintain the maximum pelletizing rate designed for the facility or a higher pelletizing rate, such as greater than 35 T / hr, greater than 36 T / hr, greater than 37 T / hr, greater than 38 T / hr, greater than 39 T / hr or greater than 40 T / hr, even in a hot and humid environment (e.g., an environment with an ambient temperature of 35° C. to 45° C.). In other words, the pelletizing rate of the PSAN pellet solution disclosed herein can be 35 T / hr to 42 T / hr or 38 T / hr to 41 T / hr, even in a hot and humid environment (e.g., an environment with an ambient temperature of 35° C. to 45° C.). In other words, the maximum pelletization rate of the PSAN pellet solutions disclosed herein can be at least 10%, at least 20%, at least 30%, at least 40%, or at least 50% higher than the maximum pelletization rate obtained with conventional LDAN pellet solutions, or the maximum pelletization rate of the PSAN pellet solutions disclosed herein can be 10% to 60%, 10% to 50%, 10% to 40%, 10% to 30%, or 10% to 20% higher than the maximum pelletization rate obtained with conventional LDAN pellet solutions, even in a hot and humid environment (e.g., an environment with an ambient temperature of 35° C. to 45° C.).

[0053] Example

[0054] The following examples are illustrative of the disclosed methods and compositions. In view of the present disclosure, those skilled in the art will recognize that modifications to these and other embodiments of the disclosed methods and compositions will be possible without undue experimentation.

[0055] Example 1 - Generation of Spheroids for Analysis

[0056] To produce spherulites, the following method was used. TM Holes with a diameter of 2.8 mm were drilled in the top of the plate to a depth of approximately 3 mm. Drain holes with a diameter of 0.9 mm were drilled in these holes. The AN solution was then added to the plate to fill the 2.8 mm holes. Once the spheroids cooled, they were removed from the TEFLON through the drainage holes. TM Push out through the 2.8 mm hole in the board.

[0057] Example 2 - Analysis of Potassium Salts

[0058] The pellets produced contained aluminum sulfate (aluminum sulfate solution from Ixom Chemicals or aluminum sulfate from Merck BDH) and AN and potassium salts dissolved in the initial solution. The following samples were prepared for analysis: 1) ANFO only (94:6), 2) AN containing 0.07% AI2SO4 (700 ppm) and 3.5 mol% KNO3, combined with fuel oil and dye (94:6), 3) AN containing 0.07% AI2SO4 and 2.5 mol% KNO3, combined with fuel oil and dye (94:6), and 4) AN containing 3,500 ppm AI2SO4 and 2.5 mol% KNO3, combined with fuel oil and dye (94:6).

[0059] The samples were placed in a circulation oven (PANASONIC TM The cycle oven was designed to simulate the thermal cycling that occurs in the field. The oven was set so that one cycle consisted of a four-hour period at 15°C followed by a four-hour period at 45°C. The samples were cycled a total of 140 times (Table 2 and Table 3). Figure 1 ).

[0060] Table 2. Crushing test data of PSAN ANFO containing aluminum sulfate Throughout the cycling process, the samples were visually observed for condition and possible degradation. In addition, crush tests were performed at different points to demonstrate the possible changes in hardness of the samples during the cycling process (using a Mark-10 ESM303 electric test stand and a Mark-10 digital dynamometer M5-20).

[0061] The crush strength (hardness) of the sample is tested during the entire thermal cycle. Figure 1 These data indicate that ANFO manufactured using PSAN can be reused to exhibit an extended shelf life of phase-stable AN using aluminum sulfate as an internal additive.

[0062] Example 3 - Production of PSAN pellets in a facility and comparison with LDAN pellets

[0063] The following samples were made by the Kaltenbach Thuring process: PSAN Sample 1 - PSAN pellets containing AN and 2.5 mol % KOH (49% KOH solution); and PSAN Sample 2 - PSAN pellets containing AN and 3.5 mol % KOH (49% KOH solution).

[0064] The temperature of conventional LDAN and PSAN samples 1 and 2 were measured over eight (8) thermal cycles using a thermocouple and data logger. For each thermal cycle, the samples were subjected to 45°C for 4 hours and then 15°C for 4 hours. Under these conditions, PSAN samples 1 and 2 easily reached the high and low temperatures in the oven, while conventional LDAN did not actually reach 45°C in 4 hours. This Figure 2 Described in. Figure 2 The temperature profiles depicted in also show the endothermic and exothermic behavior of conventional LDAN (associated with the known phase transition at 32° C.). Since PSAN samples 1 and 2 do not have a phase transition at 32° C., this is not observed in their temperature profiles.

[0065] The heating and cooling times of the PSAN pellets were then compared to those of conventional LDAN pellets. In this case, samples of conventional LDAN and PSAN pellets were placed in an oven at 50°C, and a thermocouple and data logger were used to determine the length of time it took for each of these samples to reach 50°C ( Figure 3 The samples were placed in an oven overnight and then moved to ambient conditions to determine the time required to cool the samples to ambient temperature ( Figure 4 A blank control sample (empty jar) was also used. Figure 3 and 4 As shown, the heating and cooling of the PSAN pellets are faster than those of the conventional LDAN pellets. This is due to the absence of the 32°C phase transition in the PSAN pellets.

[0066] Example 4 - Production of PSAN Pellets in Facility and Comparison with LDAN Pellets

[0067] The following samples were made by the Kaltenbach Thuring process: PSAN pellets containing AN and 2.5 mol% KOH (49% KOH solution). The PSAN pellets were also coated with 700 ppm ATH-626M. Figure 5 and Figure 6 The results from conventional LDAN pellets ( Figure 5 ) and PSAN pellets ( Figure 6 ). As shown in the figure, the phase transition of 84°C of PSAN pellets is shifted to about 95°C to 105°C, and the phase transition of 32°C is minimized.

[0068] The pelletizing rate was set to 40 T / hr and 6 pelletizing heads were online. The average ambient temperature of the environment was about 38°C. Since the phase change of 84°C is shifted to higher temperatures, the temperature limit of the tower bottom was set to 90°C. The PSAN pellet temperature at the tower bottom was also measured and is depicted in Table 3 below:

[0069] Table 3

[0070] time Number of online granulation heads Tower bottom temperature (℃) 10:00 6 82.4 10:05 6 82.2 10:30 6 81.9 10:45 6 82.0 11:00 6 81.8 12:00 6 83.9 14:00 6 85.3 15:00 6 85.7 18:00 6 83.7 20:00 6 82.7 22:00 6 82.8

[0071] As shown in Table 3, the temperature of the PSAN pellets at the bottom of the tower (82°C to 86°C) exceeds the temperature range achievable by conventional LDAN pellet production (78°C to 82°C).

[0072] Since the phase change at 32°C is minimized, the temperature of the PSAN pellets leaving the cooling mechanism (e.g., fluidized bed cooler) is set to 35°C. The temperature of the PSAN pellets when leaving the cooling mechanism (e.g., fluidized bed cooler (FBC)) is also observed. The temperature is depicted in Table 4 below:

[0073] Table 4

[0074] time Number of online granulation heads Pellet temperature (leaving FBC) 11:25 6 26.4 13:00 6 24.6 17:00 6 25.6 21:00 6 25.2 22:00 6 24.2

[0075] Typically, when the ambient temperature is greater than 35°C, the observed temperature of conventional LDAN pellets will be in the range of 29°C to 30°C, which will require a reduction in the pelletization rate. However, due to the absence of a 32°C phase transition, PSAN pellets leave the cooling mechanism (e.g., fluidized bed cooler) at a low temperature (24°C to 27°C).

[0076] As a comparison, the following fabrication parameters were achieved for PSAN pellets compared to conventional LDAN pellets:

[0077] Table 5

[0078]

[0079] Table 6

[0080]

[0081] Without further elaboration, it is believed that those skilled in the art can use the foregoing description to maximize the use of the present disclosure. The examples and embodiments disclosed herein should be interpreted as merely illustrative and exemplary, and not limiting the scope of the present disclosure in any way. It will be apparent to those skilled in the art and those who benefit from the present disclosure that the details of the above embodiments may be changed without departing from the basic principles of the present disclosure.

Claims

1. A phase-stable ammonium nitrate explosive, the explosive comprising: phase-stable ammonium nitrate pellets, the phase-stable ammonium nitrate pellets comprising: Ammonium nitrate; a potassium salt, wherein the phase-stabilized ammonium nitrate pellets comprise 2.1 to 5 mole percent of potassium ions of the potassium salt, based on the ammonium ions of the ammonium nitrate, wherein the potassium salt is selected from the group consisting of potassium hydroxide, potassium nitrate, potassium sulfate, potassium bisulfate, potassium carbonate, and potassium bicarbonate; as well as Inorganic porosity enhancers comprising: Aluminium sulfate, anhydrous or in any of its hydrated forms; wherein the phase-stabilized ammonium nitrate pellets have a fuel oil retention percentage of at least 5.7%; and wherein the phase-stabilized ammonium nitrate pellets have a bulk density of 0.84 kg / L or less, and fuel, wherein the weight ratio of the phase-stabilized ammonium nitrate pellets to the fuel is from 80:20 to 97:3; and the concentration of the inorganic porosity enhancer in the pellets is from 400 ppm to 4,000 ppm; wherein after subjecting the phase-stabilized ammonium nitrate explosive to thermal cycling 20 times, wherein one cycle comprises 4 hours at 15°C and then 4 hours at 45°C, the average crushing strength of the thermally cycled phase-stabilized ammonium nitrate explosive is greater than the average crushing strength of the phase-stabilized ammonium nitrate explosive that has not been thermally cycled.

2. The phase-stabilized ammonium nitrate explosive according to claim 1, wherein the mole % of the potassium ions based on the ammonium ions is 2.1 to 4 mole %.

3. The phase-stabilized ammonium nitrate explosive according to claim 2, wherein the mole % of the potassium ions based on the ammonium ions is 3 mole %.

4. The phase-stabilized ammonium nitrate explosive of claim 1, wherein the fuel comprises liquid fuel; wax; oil and mixtures thereof.

5. The phase-stabilized ammonium nitrate explosive of claim 4, wherein the liquid fuel comprises fuel oil, diesel, distillate, furnace oil, kerosene, gasoline or naphtha, and mixtures thereof.

6. The phase-stabilized ammonium nitrate explosive of claim 4, wherein the wax comprises microcrystalline wax, paraffin wax or oil-containing wax, and mixtures thereof.

7. The phase-stabilized ammonium nitrate explosive of claim 4, wherein the oil comprises paraffin oil, benzene, toluene or xylene oil, asphalt material, polymer oil, animal oil or other mineral oil, hydrocarbon oil or fatty oil, and mixtures thereof.

8. The phase-stabilized ammonium nitrate explosive of any one of claims 1 to 7, wherein the weight ratio of the phase-stabilized ammonium nitrate pellets to the fuel is from 85:15 to 96:

4.

9. The phase-stabilized ammonium nitrate explosive of claim 8, wherein the weight ratio of the phase-stabilized ammonium nitrate pellets to the fuel is from 90:10 to 95:

5.

10. The phase-stabilized ammonium nitrate explosive of claim 9, wherein the weight ratio of the phase-stabilized ammonium nitrate pellets to the fuel is 94:

6.

11. A phase-stabilised ammonium nitrate explosive as claimed in any one of claims 1 to 7 wherein the fuel is not an emulsion.

12. The phase-stabilized ammonium nitrate explosive of any one of claims 1 to 7, wherein the concentration of the inorganic porosity enhancer in the pellets is 400 ppm to 1,000 ppm.

13. The phase-stabilized ammonium nitrate explosive of claim 12, wherein the concentration of the inorganic porosity enhancer in the pellets is from 500 ppm to 900 ppm.

14. The phase-stabilized ammonium nitrate explosive of claim 13, wherein the concentration of the inorganic porosity enhancer in the pellets is 600 ppm to 800 ppm.

15. The phase-stabilized ammonium nitrate explosive of claim 14, wherein the concentration of the inorganic porosity enhancer in the pellets is 700 ppm.

16. The phase-stabilized ammonium nitrate explosive of claim 12, wherein the concentration of the inorganic porosity enhancer in the pellets is from 2,000 ppm to 4,000 ppm.

17. The phase-stabilized ammonium nitrate explosive of claim 16, wherein the concentration of the inorganic porosity enhancer in the pellets is from 2,500 ppm to 3,900 ppm.

18. The phase-stabilized ammonium nitrate explosive of claim 16, wherein the concentration of the inorganic porosity enhancer in the pellets is from 3,000 ppm to 3,700 ppm.

19. The phase-stabilized ammonium nitrate explosive of claim 18, wherein the concentration of the inorganic porosity enhancer in the pellets is 3,500 ppm.

20. The phase-stabilized ammonium nitrate explosive of any one of claims 1 to 7, wherein the potassium salt comprises at least one of potassium hydroxide, potassium nitrate or potassium sulfate.

21. The phase-stabilized ammonium nitrate explosive of any one of claims 1 to 7, wherein the bulk density of the phase-stabilized ammonium nitrate pellets is less than 0.84 kg / L.

22. The phase-stabilized ammonium nitrate explosive of claim 1, wherein the phase-stabilized ammonium nitrate pellets do not have a crystalline phase change at 32°C.

23. The phase-stabilized ammonium nitrate explosive of claim 1, wherein the phase-stabilized ammonium nitrate pellets do not have a crystalline phase change at 84°C.

24. A phase-stabilised ammonium nitrate explosive as claimed in claim 22 or claim 23, wherein the presence of the 32°C crystalline phase change or the 84°C crystalline phase change is determined by thermal analysis or X-ray diffraction measurements.

25. The phase-stabilized ammonium nitrate explosive of claim 24, wherein the thermal analysis comprises differential scanning calorimeter and thermogravimetric analyzer analysis.

26. The phase-stabilized ammonium nitrate explosive of any one of claims 1 to 7, wherein after thermally cycling the phase-stabilized ammonium nitrate explosive 50 times, wherein one cycle comprises four hours at 15°C followed by four hours at 45°C, the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is greater than 0.4 kg.

27. The phase-stabilized ammonium nitrate explosive according to claim 26, wherein the average crushing strength of the phase-stabilized ammonium nitrate explosive after thermal cycling is 0.4 kg to 2.0 kg.

28. The phase-stabilized ammonium nitrate explosive according to claim 27, wherein the average crushing strength of the phase-stabilized ammonium nitrate explosive after thermal cycling is 0.5 kg to 1.5 kg.

29. The phase-stabilized ammonium nitrate explosive according to claim 28, wherein the average crushing strength of the phase-stabilized ammonium nitrate explosive after thermal cycling is 0.6 kg to 1.0 kg.

30. The phase-stabilized ammonium nitrate explosive according to claim 29, wherein the average crushing strength of the phase-stabilized ammonium nitrate explosive after thermal cycling is 0.7 kg to 0.9 kg.

31. The phase-stabilized ammonium nitrate explosive of claim 26, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is 5% to 100% greater than the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

32. The phase-stabilized ammonium nitrate explosive of claim 31, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is 10% to 80% greater than the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

33. The phase-stabilized ammonium nitrate explosive of claim 32, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is 20% to 60% greater than the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

34. The phase-stabilized ammonium nitrate explosive of claim 33, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is 25% to 40% greater than the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

35. The phase-stabilised ammonium nitrate explosive of any one of claims 1 to 7, wherein the effective storage period of the phase-stabilised ammonium nitrate explosive is at least two months at an average daytime ambient temperature of 30°C to 50°C and an average nighttime temperature of 10°C to 30°C.

36. The phase-stabilized ammonium nitrate explosive of claim 35, wherein the phase-stabilized ammonium nitrate explosive has an effective storage period of at least four months.

37. The phase-stabilized ammonium nitrate explosive of claim 36, wherein the phase-stabilized ammonium nitrate explosive has an effective storage period of at least six months.

38. A method of increasing the hardness of a phase-stabilized ammonium nitrate explosive, the method comprising: There is provided a phase-stabilized ammonium nitrate explosive as claimed in any one of claims 1 to 37, and thermally cycles the phase-stabilized ammonium nitrate explosive 20 times or more.

39. The method of claim 38, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is increased by at least 5% compared to the average crush strength of the comparable phase-stabilized ammonium nitrate explosive that has not been thermally cycled.

40. The method of claim 39, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is increased by 5% to 100% compared to the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

41. The method of claim 40, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is increased by 10% to 80% compared to the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

42. The method of claim 41, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is increased by 20% to 60% compared to the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

43. The method of claim 42, wherein the average crush strength of the thermally cycled phase-stabilized ammonium nitrate explosive is increased by 25% to 40% compared to the average crush strength of the non-thermally cycled phase-stabilized ammonium nitrate explosive.

44. A method for preparing the phase-stabilized ammonium nitrate explosive according to claim 1, the method comprising: forming a phase-stable ammonium nitrate solution comprising a potassium salt, an inorganic porosity enhancer and ammonium nitrate, wherein the inorganic porosity enhancer comprises aluminum sulfate in anhydrous or any one of its hydrate forms, wherein the potassium salt is selected from potassium hydroxide, potassium nitrate, potassium sulfate, potassium bisulfate, potassium carbonate and potassium bicarbonate; and crystallizing the phase-stable ammonium nitrate solution by dropping droplets of the phase-stable ammonium nitrate solution into a prilling tower to form phase-stable ammonium nitrate pellets, wherein the temperature limit of the phase-stable ammonium nitrate pellets at the bottom of the prilling tower is at least 85° C., wherein the phase-stabilized ammonium nitrate pellets have a fuel oil retention percentage of at least 5.7%; and wherein the phase-stable ammonium nitrate pellets have a bulk density of 0.84 kg / L or less, and The phase-stabilized ammonium nitrate pellets are combined with a fuel to form a phase-stabilized ammonium nitrate explosive.

45. The method of claim 44, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is at least 86°C.

46. ​​The method of claim 45, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is at least 87°C.

47. The method of claim 46, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is at least 88°C.

48. The method of claim 47, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is at least 89°C.

49. The method of claim 48, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is at least 90°C.

50. The method of claim 44, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is between 85°C and 95°C.

51. The method of claim 50, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets at the bottom of the prilling tower is between 85°C and 90°C.

52. The method of any one of claims 44 to 51, further comprising: The phase stabilized ammonium nitrate pellets are transferred to a cooling facility.

53. The method of claim 52, wherein the cooling mechanism comprises a fluidized bed cooler.

54. The method of claim 53, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is at least 35°C.

55. The method of claim 54, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is at least 36°C.

56. The method of claim 55, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is at least 37°C.

57. The method of claim 56, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is at least 38°C.

58. The method of claim 57, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is at least 39°C.

59. The method of claim 58, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is at least 40°C.

60. The method of claim 52, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is between 30°C and 40°C.

61. The method of claim 60, wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is between 32°C and 40°C.

62. The method of claim 61 wherein the temperature limit of the phase-stabilized ammonium nitrate pellets exiting the cooling mechanism is between 35°C and 40°C.

63. The process of any one of claims 44 to 51, wherein the granulation rate is greater than 35 t / hr.

64. The process of claim 63, wherein the granulation rate is greater than 36 t / hr.

65. The method of claim 64, wherein the granulation rate is greater than 37 t / hr.

66. The process of claim 65, wherein the granulation rate is greater than 38 t / hr.

67. The method of claim 66, wherein the granulation rate is greater than 39 t / hr.

68. The process of claim 67, wherein the granulation rate is greater than 40 t / hr.

69. The process of any one of claims 44 to 51, wherein the granulation rate is 35 t / hr to 42 t / hr.

70. The method of claim 69, wherein the granulation rate is 38 t / hr to 41 t / hr.

71. The method of any one of claims 44 to claim 51, wherein the granulation rate is at least 10% higher than the granulation rate obtained with a conventional LDAN pelletizing solution.

72. The method of claim 71, wherein the granulation rate is at least 20% greater than the granulation rate obtained using a conventional LDAN pelletizing solution.

73. The method of claim 72, wherein the granulation rate is at least 30% higher than the granulation rate obtained with conventional LDAN pelletizing solutions.

74. The method of claim 73, wherein the granulation rate is at least 40% greater than the granulation rate obtained using a conventional LDAN pelletizing solution.

75. The method of claim 74, wherein the granulation rate is at least 50% greater than the granulation rate obtained using a conventional LDAN pelletizing solution.

76. The method of any one of claims 44 to claim 51, wherein the granulation rate is 1.1 to 1.6 times the granulation rate obtained using a conventional LDAN pelletizing solution.

77. The method of claim 76, wherein the granulation rate is 1.1 to 1.5 times the granulation rate obtained using a conventional LDAN pelletizing solution.

78. The method of claim 77, wherein the granulation rate is 1.1 to 1.4 times the granulation rate obtained using a conventional LDAN pelletizing solution.

79. The method of claim 78, wherein the granulation rate is 1.1 to 1.3 times the granulation rate obtained using a conventional LDAN pelletizing solution.

80. The method of claim 79, wherein the granulation rate is 1.1 to 1.2 times the granulation rate obtained using a conventional LDAN pelletizing solution.

81. The method of claim 63, wherein the ambient temperature is 35°C to 45°C.

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