Sci. Tech. Energetic Materials, Vol．８０,No．５,２０１９ 171 Research paper Downgrading of detonation properties of ammonium nitrate using calcium carbonate, dolomite, and fly ash Ahmet Ozan Gezerman＊† ＊Department of Chemical Engineering, Faculty of Chemical and Metallurgical Engineering, Yildiz Technical University, Yıldız Mh., 34349 Beşiktaş/Istanbul, TURKEY Phone: +90-532-6538505 †Corresponding author: [email protected] Received: September 28, 2018 Accepted: July 23, 2019 ４ ２ Abstract ９ Aprocess has been developed for minimizing the detonation hazard of ammonium nitrate that is used as a chemical fertilizer, by adding calcium carbonate, dolomite, and fly ash. The detonation enthalpies and velocities of the obtained ammonium nitrate derivates were measured, revealing their suitability for application in fertilizer production. These results showed that, for a pure ammonium nitrate solution, coating with 0-20 wt% fly ash and adding a maximum of 25 wt% limestone and dolomite would eliminate the detonation problem associated with ammonium nitrate. It was also revealed that chemicals such as lead azide, lead styphnate, and mercury fulminate, which normally increase the detonation velocity of ammonium nitrate, did not do so when it contains CaCO３ (12.5%), CaMg(CO３)２ (7.5%), or fly ash (0- 20%). Even with the addition of lead saltsandmercury fulminate, the detonation velocity of calcium ammonium nitrate continues to decrease. Thus, the detonation hazard of calcium ammonium nitrate can be mitigated. Keywords:ammonium nitrate, calcium carbonate, dolomite, fly ash, detonation 1. Introduction this method, various fly ash compounds were used to Ammonium nitrate (AN) is widely recognized as an decrease detonation enthalpy and they have concluded important fertilizer. Increasing consumer demands have that such a measure decreases the detonation enthalpy of further stimulated the production of AN as well as the ammonium nitrate２）.Resende et al. studied the detonation modification of various properties of this compound. properties of mixture of ammonium nitrate and various However, AN is inexpensive and readily available, and can materials such as biodiesel and sugar cane and they have be easily triggered to undergo explosion; hence, there is an found that the detonation velocities of these mixtures had increased concern regarding the possible misuse of this been mitigated３）.Theyalsoreplaced the fuel oil in compound as an explosive for terrorist activities. For this commercial ammonium nitrate/fuel oil (ANFO), which is a reason, the governments of many countries have imposed widely used bulk industrial explosive, with rice straw, corn strict limitations on the industrial-scale production and the cob, sugarcane bagasse, and biodiesel３）. use of AN, leading to consumer demand for fertilizer not Zygmunt and Buczkowski studied the explosive being satisfied. This has also led to the increased cost of properties of ammonium nitrate with ANFO４）.According AN-based fertilizers, thus limiting their use in agriculture. to this study, the porous structure of ammonium nitrate Several formulations and processesaimed at has a significant influence on the detonation properties of suppressing the detonation probability of AN have been ANFO explosives. As the porosity of ammonium nitrate proposed by the past researchers１）.Although various increases, the detonation velocity of ANFO increases. chemical compositions have been designed and applied to Therefore, to limit the detonation sensitivity of ammonium degrade the detonation properties of this compound, they nitrate, the porosity of ammonium nitrate should be are not intended to satisfy consumer requirements. In decreased. To better understand these properties, they another study, Taulbee et al.２） developed a method to investigated the oil adsorption capacity of the porous reduce the detonation enthalpy of ammonium nitrate. In structure of ammonium nitrate４）.Inanother study, 172 Ahmet Ozan Gezerman Buczkowski and Zygmunt attempted to suppress the was observed that a decrease in water absorption by detonation probability of AN by diluting it with different ammonium nitrate particles was prevented thereby concentrations of dolomite５）.Experiments show that even reducing physical contact between the ammonium nitrate mixtures of milled fertilizers containing 40% dolomite and particles and ultimately resulting in a reduction in the aluminum can detonate５）.Bohanek et al.６） studied the detonation potential12）.Ledoux and De Moor prepared an detonation properties of ANFO explosives using penthrite. ammonium nitrate mixture in which the explosive They reported that detonation velocity decreases with an material contained urea calcium nitrate (UCaN), urea increase in penthrite６）. magnesium nitrate (UMgN), urea calcium phosphate On the other hand, to measure the detonation velocity, a (UCaP), urea magnesium phosphate (UMgP), urea different method was developed by Miyake et al.７）.Intheir superphosphate (USP) and mixtures thereof to minimize study, the detonation velocity of an ANFO mixture was the detonation capacity13）.Asaresult, they were able to measured using JIS G3454 steel tube. This tube had a 35.5 limit detonation energy of the ammonium nitrate. Their mm inner diameter, a 42.7 mm outer diameter and it was study provided an important insight into understanding 400 mm in length. The ANFO was detonated in this tube the detonation properties of ammonium nitrate with other ! and the detonation velocity was recorded７）.They explosive materials. Gezerman and Çorbacıoglu studied prepared ANFO samples using the same AN pore means of minimizing the antisocial use of ammonium diameter and pore volume and found that the detonation nitrate by mixing it with dolomite and calcium carbonate, velocity (3.85 km s－１)wasthehighest for those particles and also coating it with fly ash (10-50%). They with the smallest diameter ("!!#"mm). After aging for 12 successfully maintained the nitrogen concentration (26%) months, the ANFO detonation velocities decreased, in the ammonium nitrate fertilizer while simultaneously suggesting that the ANFO reaction was influenced by the mitigating the detonation velocity14）.Gezerman, in another physical and chemical properties of the AN particles and study, increased the concentration of the fly ash (max oil during storage. 20%) and combined dolomite and calcium carbonate with Another study on reducing the detonation enthalpy and ammonium nitrate15）.Detonation tests on ammonium velocity of ammonium nitrate was performed by Adamo nitrate were conducted using the Dautriche method, et al.８）.Inthat study, calorimetric experiments were revealing that the detonation velocity was reduced15）. performed and during the ammonium nitrate degradation, Chaturvedi and Dave proposed reaction mechanisms role of water was investigated as the degradation occurring during the detonation of ammonium nitrate16）. progressed. In addition, the possibility of the reaction During the detonation reaction, the temperature increased ο between ammonium nitrate and the sodium salt of to 230 Candnitrogen oxides, such as NO and NO２,were dichloroisocyanuric acid as a rate-limiting step was created as thermal decomposition products16）.Several investigated. In another study that measured the studies have addressed the limiting effects of different detonation velocities of ammonium nitrate mixtures, Van materials such as Al powders on the detonation properties der Steen et al.９）measured those of non-ideal, low-density of ammonium nitrate５）.Onesuchstudy found that the ammonium nitrate by using tubes with different addition of a 30% concentration of aluminum powder (with diameters and wall thicknesses. Also, they determined aparticlesizeof6µm) to an ammonium nitrate solution that the tube diameter has a much greater effect on the decreased the detonation energy dramatically５）.Leong et detonation velocity than the confinement９）.The al.17） presented a patented method for preventing CAN interferometer acted on those elements resulting in the fertilizer from being used as a precursor for explosives, failure of the detonation velocity testing procedure10）.In e.g., for terrorist attacks. The CAN fertilizer was reacted another ammonium nitrate detonation study, in order to with an organic polymer, producing a hydrogel that does understand the detonation mechanism of ammonium allow the fertilizer to detonate. They used an organic nitrate with the ultimate aim of prevention, Na２SO４ in KCl polymer mixture of polyethylene glycol (PEG) , aqueous solutions were studied. The study attempted to hydroxyethyl cellulose (HEC), carboxymethyl cellulose prevent the thermal decomposition of the ammonium (CMC) and cellulose gum for this process. Cranney et al.18） nitrate11）.Inanother study, Taulbee set out to reduce the produced non-detonable AN prills using surfactants such explosive potential of ammonium nitrate by applying a as non-polymeric polyisobutylonene succinic anhydride mixture of urea and ammonium nitrate12）.Thesurface of (PIBSA)-based polymeric emulsifiers, which react with the the ammonium nitrate was coated with gypsum, calcium kaolin used to coat the surface of the AN (to suppress sulfate hemi-hydrate, calcium carbonate, calcium nitrate, oxidation), thus decreasing the heat of detonation of the soda lime, potassium sulfate, magnesium sulfate, bentonite, CAN. In another study examining the detonation, NaCl silica gel, potassium phosphate, potassium nitrate, was added to the ammonium nitrate solution, and with the potassium chloride, sodium sulfate,