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DOI: http://dx.doi.org/10.20534/AJT-17-5.6-33-38
Turdialiev Umid Muhtaralievich, Institute of General and Inorganic Chemistry Academy of Sciences of the Republic of Uzbekistan, senior scientific researcher, the Laboratory of Phosphate fertilizers
E-mail: eco-planning@mail.ru Namazov Shafoat Sattarovich, Institute of General and Inorganic Chemistry Academy of Sciences of the Republic of Uzbekistan, Doctor of Sciences, Professor E-mail: igic@rambler.ru Seytnazarov Atanazar Reypnazarovich, Institute of General and Inorganic Chemistry Academy of Sciences of the Republic of Uzbekistan, Doctor of Science,
E-mail: begloff@mail.ru Mirsalimova Saodat Rahmatjanovna, Fergana polytechnic institute, associate professor, department of chemical technology E-mail: igic@rambler.ru
AMMONIUM NITRATE WITH BENTONITE CLAYS ADDITIVE FROM UZBEKISTAN
Abstract: The samples of nonpacking AN obtained by bentonite in NH4NO3 melt subsequent prilling bentonite clay's melt have been prepared. It has been that bentonite additives in NH4NO3 melt containing 1% of humidity at AN:BG = 100: (1-1.5) roses strength of AN granules in 1.5-2.0 fold while the packing reduces in 2-3 times in comparison to saltpetre containing magnesite. Furthermore, the granules hold 50 and more cycles of 20%50 ° C heat-cool. When cooling the melt with bentonite it was revealed that absence of III phase and presence of direct transition of IV^II that differs from pure NH4NO3 leading to stable behaviour of AN at variations in temperature (25-55° C) without destruction of granules. This phenomenon is important during the storage and handling of products.
Keywords: ammonium nitrate, bentonite clay, melt, granulation, nonpacking, strength, packing, thermo stability, porosity, blotting capacity, polymorphic transition, density and viscosity.
Introduction
The majority nutritious for plants are nitrogen, phosphorus and potassium. Namely these three elements provide the growth of farming industry. In Uzbekistan there are JSC "Maxam-Chirchik", "Navoiazot" and "Ferganaazot" produce nitrogen
fertilizers which assortment consist of ammonium nitrate (AN), urea and ammonium sulphate. In addition, three JSC such as "Ammophos-Maxam", "Samarkandkimyo" and "Kokand superphosphate zavod" produce phosphorus containing fertilizers namely ammophos, suprephos-NS, ammonium
sulphate-phosphate, PS-Agro, feed ammonium phosphate, nitro calcium phosphate, simple and enriched superphosphate. Unitary enterprise (UE) "Dehkanbad potassium fertilizer plant" lets out just potassium chloride. In 2015 nitrogen industry produced 942.72 thousand tonnes of nitric fertilizers in amount of 100% in form 1646.66 thousand tonnes of AN, 586.66 thousand tonnes of carbamide and 192.65 thousand tonnes of ammonium sulphate.
Ammonium nitrate is all-round fertilizer that uses effectively on all type of soils at introduction under various crops. It can be introduced as basal dose and additional fertilizing. However, this fertilizer has two severe drawbacks such as packing during the storage and high explosion hazard [1-3].
Introduction modifying additives to AN improves its consumer properties. One of the best additive eliminating AN packing is magnesia. Today our manufactures use caustic magnesite MgO and
brusite Mg(OH)2 as additives for AN, bought from abroad that leads to increase prime prise. In terms of large-tonnes of AN it is necessary to replace both magnesite and brusite to local raw materials to save currency. For that, bentonite clay can be available rather reserves are quite more. By the way, there has been the approximately 200 deposits and developments of bentonite clays with reserves more than 2 billion tonnes in Uzbekistan [4].
Materials and methods
The composition and physic-mechanical properties of bentonite from Azkamar, Kattakurgan, Lagon and Navbakhor (brand PPD - carbonate and polygor-site, as well as PBG - alkaline-earth), which worked out, are summarized in table 1 and 2. In order to obtain modified AN it was used AN brand "pure" as the main component. Moreover, granular NH4NO3 and industrial product, AN containing 34.6% of N and 0.28% of MgO were used for comparison.
Table 1. - Chemical composition of initial bentonite clays from various fields
Components Content, weight%
Azkamar Kattakurgan Lagon Navbahor
Brand PPD Brand PBG
SiO2 50,34 57,89 49.73 46.06 72.23
AlA 15,21 16,71 14.74 8.78 8.82
FeA 5,67 5,19 5.57 3.0 3.93
CaO 4,76 1,12 2.26 12.2 1.26
MgO 2,3 2,9 4.45 4.33 1.81
СО2 3,41 < 0,2 2.97 9.35 0.20
К2 о 2,36 3,92 4.75 1.05 1.33
Na2O 2,31 1,68 2.15 0.75 1.12
SO, 1,48 < 0,10 0.57 1.39 1.10
PA 0,13 0,14 0.1 0.77 0.50
Н2 о 5,42 6,17 3.80 6.0 4.37
Table 2. - Physic-mechanical behaviours of bentonite clays from different deposits
Properties П оказатели
Azkamar Kattakurgan Lagon Navbahor, brand PPD
1 2 3 4 5
Humidity, % 2.23 2.15 2.38 1.62
Free density, г/см 3 0.796 0.641 0.792 0.620
Density with compaction, г/см 3 1.193 0.946 1.074 0.916
Angle of slope, degree. 26°53' 20°33' 17°25' 24°50'
1 2 3 4 5
Friability, sec. 18.33 17.42 14.17 16.27
Hygroscopic point, % 37.5 38.0 38.0 38.5
Moisture capacity, % 6.91 7.14 6.21 8.26
PH of 10% suspension 7.46 7.33 7.38 7.40
In current study there has been that composition and properties of nonpacking AN obtained based on bentonite clay (BC) and melt ofAN with weight ratios AN: BC from 100:0.5 to 100:3.0. Control on quality of AN obtained with bentonite was conducted as follows: nitrogen content, strength, caking, thermal resistance of granules was determined recurrent cycles of heat-cool at 201>50 ° C, thermal stability was defined by buffer action, porosity, blotting capacity, and polymorphic transmission of NH4NO3. During the exploration it was studied that effect of bentonite on rheological properties of AN melt. Nitrogen content in product was determined by Kjeldal, ammonia distillation in alkaline condition with Devard's melt subsequent titration [5].
Strength of granule according to [6], but packing by express technique [7]. Measure of granule porosity was defined by volumetric method to [1]. Blotting capacity of granule in towards to liquid fuel (solar oil) was determined on granular porous AN brand "pure", according to TU 6-03-372-74. Density of nitrate-bentonite slurry was found by picnomet-ric, and viscosity by efflux method. The polymorphic transformation ofAN was defined in a range ofheat-cool temperature from 25 to 175 ° C - from 175 to 25 ° C on equipment NETSCH STA 409 PC/PG by fixing their caloriferic effect. The thermal resistance of granule for recurrent cycles of heat-cool at a range of 20<>50 ° C was determined by [8].
Table 2 shows that bentonites containing 1.622.38% of humidity have density such as 0.796 g/ cm3 for Azkamar, 0.641 g/cm3 for Kattakurgan, 0.792 g/cm3 for Lagon and 1.21 g/cm3 Navbahor PPD. Angle of natural slip of bentonite clay is 1726 degree. However, their flowability is steady, and spreaded without difficulty. Limiting moisture capacity is 6.21-8.26%, but much higher humidity the
raw loses its friability. As the main clayey mineral in bentonite are montmorillonite, kaolinite, polygor-site illite and chlorite. Besides, these minerals there are calcite, quartz, potassium spar, baryte, and so on. Composition and properties of bentonite clays allow forecasting possibility to use them as AN's modifier. Preparatory to introduction of them into AN melt the additives were milled till size 40 micro and dried till 1.0 % of humidity. For preparation of operative embodiments certain amount of pure NH4NO3 was melted at 175 ° C. Following that, weighed portion of bentonite was fed into the melt. Obtained bentonite-nitrate melt was held in 3 minutes after that it was granulated by prilling way.
Results and discussion
It is revealed that additive from any type of bentonite reduces packing of AN. The more of amount of bentonite the higher strength, thermal resistance of granules grow and the less packing of ones. In fact, that nonpacking AN with less 34% of N possesses sufficient strength of 1.90-3.85 MPa and can hold 50 and more cycles ofheat-cool. The packing ofAN with ratio of AN:BG = 100: (1-1.5) is less in 2-3 times (table 3) than AN with magnesite (4.67 kg/cm2). In that case, AN added Navbahor bentonite has the most strength 2.50-2.94 MPa.
It has been established that granule strength of pure NH4NO3 without additives constitutes 1.36 MPa, while that of AN with magnesia makes 1.58 MPa. The granule strength ofpure NH4NO3 has already after 10 thermal cycles destructed at 5%, but after 80 ones destructed completely. In terms of the granules with magnesia has crushed after cycles while since 100 cycles it has destructed in full. Whereas, AN containing bentonite with 2.0% of humidity retains its wholeness since 50 thermal cycles. After all, the degradation of granules starts just since 60 cycles.
Also it is seen from table 3 that porosity of pure NH4NO3 and AN with magnesia constitute 22.0 and 9.10% respectively. But addition of Azkamar bentonite in NH4NO3 melt from 1 to 3 g in towards to 100 g of NH4NO3 makes to reduction the porosity granule from 7.71 to 6.85% using Navbahor bentonite (brand PPD), from 7.92 to 7.01% Kattakurgan bentonite from 7.73 to 6.89% and from 7.84 to 6.93% Lagon bentonite. Depend-
ing the upon ratio AN:BC blotting capacity of solar oil by AN granules oscillates in a range 2.88-3.77; 3.06-3.90; 2.97-3.81 and 3.02-3.92 g of fuel in towards to 100 g of product, respectively Azkamar, Navbahor, Kattakurgan and Lagon. However, this figure for pure NH4NO3 was 4.82 g while AN containing 0.28% of MgO was 4.33 g. In fact, that above mentioned confirms reasons growth of the strength of fertilizers' granule.
Table 3. - Impact of initial bentonite'moisture and its amount on granule strength, as well as AN packing
Weight ratio of AN: BC N, % Strength of granule, MPa Packing, kg/cm2 * Porosity of granule, % * Blotting capacity of granule, g
With Navbahor ' bentonite (PPD)
100: 0.5 34.29 2.01 2.28 no determined no determined
100: 1.0 34.10 2.50 2.17 7.92 3.90
100: 1.5 33.92 2.94 1.95 no determined no determined
100: 2.0 33.71 3.15 1.51 7.44 3.22
100: 2.5 33.63 3.30 1.35 no determined no determined
100: 3.0 33.45 3.51 1.69 7.01 3.06
With Azkamar bentonite
100: 0.5 34.29 1.90 1.89 no determined no determined
100: 1.0 34.12 2.30 1.67 7.71 3.77
100: 1.5 33.94 2.52 1.52 no determined no determined
100: 2.0 33.75 2.74 1.35 7.28 3.09
100: 2.5 33.56 2.95 1.28 no determined no determined
100: 3.0 33.42 3.12 1.44 6.85 2.88
With Lagon bentonite
100: 0.5 34.30 2.14 2.09 no determined no determined
100: 1.0 34.11 2.14 1.77 7.84 3.92
100: 1.5 33.95 2.54 1.69 no determined no determined
100: 2.0 33.78 2.82 1.41 7.40 3.26
100: 2.5 33.60 3.34 1.33 no determined no determined
100: 3.0 33.46 3.85 1.59 6.93 3.02
With Kattakurgan bentonite
100: 0.5 34.28 1.96 2.74 no determined no determined
100: 1.0 34.14 2.20 2.25 7.73 3.81
100: 1.5 33.96 2.50 1.98 no determined no determined
100: 2.0 33.77 2.74 1.74 7.30 3.17
100: 2.5 33.61 3.21 1.52 no determined no determined
100: 3.0 33.44 3.60 1.87 6.89 2.97
NH4NO3 "pure" 34.96 1.58 5.62 22.0 4.82
AN with 0.28% of MgO 34.6 1.32 4.67 9.10 4.33
* with additive of Navbahor bentonite brand PPD
Thermal explores conducted in a range of heat-cool from 25 to 175 ° C - from 175 to 25 ° C presented (table 4) that melting NH4NO3 (without additives) passes through the transformation IV^III; IIMI; IM and I^melt. In case, polymorphis transition IV^III is 46 ° C, IIMI - 85 ° C, IM - 126 ° C, while phase transition under I^melt is 169 ° C. Because of polymorphic transition IV^III leads to large deformation of crystal lattice. Moreover, for AN with bentonite additives 4 consequent modification transitions observed typical to NH4NO3,
It has been revealed the value of polymorphic transition observed during the cool is lower than heat. When cooling melt of pure NH4NO3 melt transition melM; MI; IMII u IIMV takes place at 169; 125; 48 and 30 ° C respectively. At that time cooling AN with bentonite modification transition occurs through melM; MI; IMV. As result, III phase does not generate, that is transition IMV passes III phase that provides lesser deformation of crystal lattice, as well as sufficient strength. Following that, bentonite additive stabilizes IV modification during the storage and application ofAN at temperature fluctuation till +51° C dramatic volume change of its crystals con-
but differenced on temperature transition and ratio AN : BC. So, the temperature transition IV^III, IIMI, IM and I^melt changed 56.1; 91.1; 133.6 and 174.2 ° C, respectively when AN : BC = 1:0.5 whereas at AN : BC = 1 : 2.5 it was 58.7; 92.3; 134.1 and 170.3 ° C using Azkamar bentonite. As seen of them that additive of bentonite reduces considerably melting point and crystallization of NH4NO3. Similar pattern can be observed and the rest type of bentonites. In that case, they differenced each other on value indicated figure.
nected with modification transition will not takes place.
Therefore, increase in temperature monotonous reduces in both density and viscosity ofAN melt independently from amount of bentonite. In studied ranges ratio AN : BC (100 : 0.5-3.0) and temperature (165-185° C) density and viscosity of all bentonite-nitrate melts (1.437-1.65 kg/cm3 and 4.88-9.14 cps respectively) differenced slightly on viscosity of AN containing magnesia (1.433-1.454 kg/cm3 and 4.85-5.91 cps) and is quite acceptable for prilling.
Thus, bentonite clays on elimination ofAN packing can change completely imported additives name-
Table 4. - Modification transition temperature based on melt of AN and Azkamar and Kattakurgan bentonites
Weight of AN: BC Peak value on the curve
IV^III IIMI IM I^nAaB nAaB^I MI IMII IIMV II^IV
Heat from 25 to 175° C Cool from 175 to 25° C
NH4NO3 46 85 126 169 169 125 48 30 —
With Azkamar jentonite
100: 0.5 56.1 91.1 133.6 174.2 167.4 122.2 — — 49.3
100: 1.0 58.2 92.0 133.7 173.4 167.0 122.2 — — 49.9
100: 1.5 59.0 92.6 133.9 172.3 166.5 122.4 — — 50.1
100: 2.0 58.3 93.0 134.0 171.1 166.2 122.6 — — 50.4
100: 2.5 58.7 92.3 134.1 170.3 166.0 123.0 — — 50.6
With Kattakurgan bentonite
100: 0.5 55.6 90.8 133.4 174.0 167.4 122.2 — — 49.8
100: 1.0 56.0 91.4 133.5 173.2 167.2 122.3 — — 50.1
100: 1.5 56.5 92.1 133.6 172.0 166.9 122.6 — — 50.3
100: 2.0 57.2 92.5 133.7 170.3 168.2 123.0 — — 50.5
100: 2.5 57.7 93.1 133.9 169.1 167.8 123.2 - — 50.6
ly brusite and magnesite. The AN modified by ben-tonite exceeds industrial AN (State standard 2-85) on physic-mechanical figures. As bentonite clay is inexpensive and available that provides economic expediency for AN manufacture.
Conclusion
Finally, there have been investigated the physic-mechanical properties of (disperse composition, moisture, apparent density, angle slope, fluidity, pH, hygroscopicity, moisture capacity) Uzbek bentonite. Furthermore, it was studied that preparation process of nonpacking AN with bentonite in the NH4NO3 melt (99,85 % solution) at 175 0C before its granulation by prilling way. In that case, the amount of additive was changed from 0.5 to 3.0 g in towards to 100 g of NH4NO3. Also the composition and properties were determined. In order to obtain nonpacking AN, which possess sufficient strength (1.90-3.85 MPa)
hold 50 and more cycles of heat-cool (201>50 0C), while humidity of bentonite should be no more 1-2%. To compare the strength of pure AN makes 1.36 MPa while AN with magnesia is 1.64MPa. The packing AN with ratio AN: BC = 100 : 1-1.5 that is less by 2-3 times than AN with magnesia (4.67 kg/cm2). When studying polymorphic transition in cycle heat-cool (from 25 to 175 - from 175 to 25 0C) it was shown that with cooling melt of AN with bentonite transition melt^I; MI h II^IV takes place subsequently. Accordint to III phase does not form because of polymorphic transition IV^II passes III phase that provides lesser deformation of crystal lattice and the largest strength of granules. A base of the above mentioned rheological properties (density and viscosity) of bentonite-nitrate melts were defined. The result obtained can be available for granulation by prilling.
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