Ammonium nitrate melting temperature

Ammonium nitrate decomposes into nitrous oxide and water. In the solid phase, decomposition begins at about I50°C (302°F) but becomes extensive only above the melting point (I70°C) (338°F). The reaction is first-order, with activation energy about 40 kcal/g mol (72,000 Btii/lb mol). Traces of moisture and Cr lower the decomposition temperature thoroughly dried material has been kept at 300°C (572°F). All oxides of nitrogen, as well as oxygen and nitrogen, have been detected in decompositions of nitrates. 

When it is mixed with potassium nitrite in the melted state (440°C), ammonium nitrate detonates. The presence of rust decreases the temperature of the explosion to 80-120°C. This behaviour is linked to the chemical incompatibility of the nitrite ion and ammonium ion. 

Cobalt reacts violently or even explosively with ammonium nitrate at a temperature close to its melting point ( 200°C). 

Like many metals, already described, lead reacts violently and sometimes explosively in melted ammonium nitrate at a temperature which is lower than 200°C. 

The dinitramide ion is stable in both acidic and basic solutions between pH 1-15 at room temperature but is slowly decomposed in the presence of strong concentrated acid. In contrast to alkyl V,V-dinitramines (Section 6.11.2) where the central nitrogen atom is highly electron deficient, the dinitramide anion has its negative charge delocalized over both nitrogen and oxygen atoms with the consequence that the N-N bonds are less susceptible to rupture. However, the dinitramide anion is not as stable as the nitrate anion ammonium dinitramide melts at 92 °C and decomposition starts at 130 °C. 

Ammonium nitrate (AN NH4NO3) is a white, crystalline material, the crystal structure of which varies with temperature.melting point is 442 K and its heat of fusion is 71.4 kj kg . Though the mass fraction of oxygen of AN is 0.5996, it is highly hygroscopic and absorbs moisture from the atmosphere to form liquid AN acid. This limits its application in propellants and pyrolants. However, AN is widely used as an oxidizer of explosives such as slurry explosives and ANFO (ammonium nitrate fuel oil) explosives. 

DSC and DTA measurements show melting of ADN, NH4N(N02)2, at 328 K, the onset of decomposition at 421 K, and an exothermic peak at 457 K.l l Gasification of 30% of the mass of ADN occurs helow the exothermic peak temperature, and the remaining 70% decomposes after the peak temperature. The decomposition is initiated by dissociation into ammonia and hydrogen dinitramide. The hydrogen dinitramide further decomposes to ammonium nitrate and NjO. The final decomposition products in the temperature range 400-500 K are NH3, HjO, NO,... 

Manueli and Bernardini [17] proposed an easily fusible mixture consisting of ammonium nitrate, guanidine nitrate and nitroguanidine. According to them such mixtures may be melted at a temperature below 130°C. The explosive Albit, based on Manueli and Bernardini s patent, consisting of six parts of ammonium nitrate, two parts of guanidine nitrate and two parts of nitroguanidine, has been used in Italy. 

Ammonium nitrate exists in the form of crystals, melting at 169.6°C. It occurs under five crystalline modifications distinguished by the transition temperatures ... 

The increase in the rate of decomposition under the influence of added Cr203 and K2Cr207 is shown on Figs. 171 and 172 respectively.lt has been found that an increase of the rate occurred only at temperatures near to the melting point of the samples. Guiochon [17] also found that cobalt salts increase the rate of thermolysis of ammonium nitrate. Other mineral salts (of manganese, nickel and copper) have a similar but much weaker action. A large number of salts of other metals are without any noticeable action. 

Tower size Prill tube height, ft Rectangular cross section, ft Cooling air rate, Ib/h inlet temperature temperature rise.°F Melt Type Urea 130 11 by 21.4 360,000 ambient 15 Ammonium Nitrate... 

In a i-l. round-bottom flask is placed an intimate mixture of 210 g. of dicyanodiamidc (2.5 moles) and 440 g. of ammonium nitrate (5.5 moles) (Note 1). The flask is introduced into an oil bath at no-1200 and the temperature of the oil is raised during about half an hour to 160°. The bath is then held at this temperature (Note 2) for three hours. During the first hour the mass melts to a clear liquid which begins to deposit crystals and finally sets to a solid cake (Note 3). At the end of three hours the flask is removed from the bath the product is allowed to cool and is extracted on the steam bath with successive quantities of water (about 2 1. is necessary to bring all soluble material into solution) (Note 4). The solution is filtered to remove white amorphous insoluble material (ammelinc and ammelide) (Note 5). 

The mixture, known as TNT oil , generally melts within a wide temperature range, for example from room temperature up to 60°C. It may be used as a component of ammonium nitrate explosives for the mining industry. 

Alkali metal nitrates have comparatively low-melting points and the solid nitrates are excellent oxidizers at higher temperatures. Potassium nitrate is used as an oxidizer in black powder (75wt% KNO3, 15% charcoal, 10% sulfur). Fertilizer mixtures commonly contain ammonium nitrate or potassium nitrate, sometimes sodium or calcium nitrate as nitrogen compounds. Ammonium nitrate is also used as an explosive or as an oxidizer in an explosive mixture. Some properties of important nitrate fertilizers are summarized in Table 31. 

Hie precursors, cerium(TV) ammonium nitrate (NH4)2Ce(N03)3 and praseodymium(lll) nitrate Fh-(N03)3 6H20, are added in a i I weight ratio to the molten salts at 673 - 873 K, and the melt is maintained for 15 - 120 min. After the melt is quenched to room temperature, the reaction products are washed with water and then dried at 393 K. Well-crystallized Ce,.jPr,02 (x = 0 - 10) powders with very fine size (10 - 20 nm), narrow size distribution, and a clearly spherical shape are obtained. 

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