Search

The influence of cobalt, copper, iron(III), manganese and zinc nitrate salts on phase transitions and thermal stability of ammonium nitrate (AN) has been studied and discussed. Differential thermal analysis/differential scanning calorimetry coupled with thermogravimetry and mass spectrometry were used to evaluate the stability of analyzed systems. Each nitrate salt was appropriately mixed with ammonium nitrate to create samples with AN:salt mass ratios of 4:1, 9:1 and 49:1. It was concluded that the addition of every studied nitrate influenced phase transitions of AN. Most analyzed salts decreased the stability of AN by accelerating its exothermic decomposition process. Iron and cobalt nitrates were defined as the most hazardous additives, resulting in a creation of a highly destabilized mixture. Copper and manganese nitrates were also defined as catalysts of the AN decomposition process, lowering the initial decomposition temperature and increasing the rate of the observed process. Zinc nitrate hexahydrate was the only salt considered to be relatively neutral in such systems, especially in small amounts. The study allowed to define the influence of selected metal nitrate salts on the thermal stability of AN under conditions that are considered as potentially unsafe for such systems. [ABSTRACT FROM AUTHOR]

• Potassium salts influence phase transitions of ammonium nitrate. • Potassium chloride accelerates and amplifies the exothermic decomposition. • Carbonates and metabisulfite are too reactive for industrial use. • Potassium phosphates, nitrate and sulphate inhibit the decomposition. • Small amounts of salts tend to worsen thermal stability of ammonium nitrate. Ammonium nitrate (AN) has proven to be an unstable and hazardous component of mineral fertilizers. In order to analyze the influence of various potassium salts on thermal properties of ammonium nitrate, differential thermal analysis coupled with thermogravimetry and mass spectrometry was used. Each potassium salt was mixed with AN to create samples with AN:salt mass ratios of 4:1, 9:1 and 49:1. It was concluded that an addition of potassium influences phase transitions of AN. Depending on the salt used, an exothermic decomposition of AN was either accelerated (potassium chloride) or inhibited to the varying degree. Carbonate salts and potassium metabisulfite were too reactive to be used in a fertilizer production, while nitrate, sulphate and both phosphates are considered to be appropriate additives and could be used in a multicomponent fertilizer production. [ABSTRACT FROM AUTHOR]