AMMONIUM NITRATE: THE POTENT EXPLOSIVE

AMMONIUM NITRATE: THE POTENT EXPLOSIVE

-       By Sneha Kumari

-       Batch(2k18), Deptt. of Chemical Engg.

-       BIT Sindri, Dhanbad

Chemical Industries are foundation stones to a variety of tertiary industries, but the mishandling of these produced chemicals quite often lead to fatal accidents. This poses a risk to any industry that stores, transports or uses these chemicals. One of the many sensitive chemicals is the ‘Ammonium Nitrate'. The world has very often witnessed circumstantial explosions of this chemical and Beirut, Lebanon is one of the recent examples.

Ammonium Nitrate i.e.  NH₄NO₃  is a white/colorless crystalline solid that is water-soluble and hygroscopic as a solid. The compound is predominantly used in fertilizer industry and as explosives. Though, quite often the latter one comes to play due its excessive sensitivity to heat. The production of this compound involves the reaction between ammonia and nitric acid, where ammonia is used in anhydrous form and the nitric acid is concentrated. The reaction itself is violent owing to its exothermic nature.

Since the compound is fairly soluble in water and contains about 33% nitrogen, it is widely used as fertilizers. Ammonium nitrate was said to be developed by Germans which they used as fertilizers instead of Chilean Nitrates since it is a lot cheaper.

Over the years, the storage and usage of Ammonium Nitrate has been a crucial task. The compound at normal temperatures is not dangerous and even on heating it starts decomposing non-explosively into gases of oxygen, nitrogen, and water vapor; however, it can be induced to decompose explosively by detonation into nitrous oxide and water vapor. Large stockpiles of the material can be a major fire risk due to their supporting oxidation, and may also detonate. At 32.2 degrees Celsius (89.96 degrees Fahrenheit), ammonium nitrate changes its atomic structure, which in turn changes its chemical properties. When large quantities of ammonium nitrate are stored in one place, heat is generated. If the amount is sufficiently vast, it can cause the chemical to ignite. Once a temperature of 170°C is reached, ammonium nitrate starts breaking down, emitting nitrous oxide, better known as laughing gas. Any sudden ignition causes ammonium nitrate to decompose directly into water, nitrogen and oxygen, which explains the enormous explosive power of the salt.

Research shows the possibility of two patterns that lead to the compound's explosion. The first one happens to be the case wherein an explosive charge goes off in the mass, by the detonation of a shell thrown into the mass, or by detonation of an explosive mixture in contact with the mass. The second case explains the explosion due to fire occurred by a combustible material in the ammonium nitrate itself.

EXPLOSIONS OVER THE YEARS

The year 1921, experienced a massive blast at a BASF chemical plant in Ludwigshafen in the German state of Rhineland-Palatinate. About 400 metric tons of a mixture of ammonium sulfate and ammonium nitrate exploded, killing 559 people and injuring 1,977. The effect of which could be heard as far away as Munich, which is some 300 kilometers distant. Another major explosion took place in USA in April,1947 where a ship carrying around 23,00 tons of this compound exploded which also induced another vessel to burn and explode. This incident even knocked two planes down that were flying in the low sky and killed over 500 people in total.

Furthermore, countries like China (2005), Mexico (2007),  North Korea (2004), France (2001) and many more have witnessed such explosions. The Beirut explosion is the latest addition to this list of unfortunate blasts  that caused immense damage throughout the city from the shock wave that was reportedly so intense that it was felt in Cyprus, an island about 250 km (150 miles) north-west of Lebanon. Infact a giant orange cloud was seen following the detonation that injured around 6000 people and was deadly for over 200 civilians.

The table below shows the world wide destruction caused by the mishandling of Ammonium Nitrate.

 

LOCATION	DATE	CASUALTIES	AMOUNT OF AN in TONs
USA (New Jersey)	14th Jan, 1916	1	1.81
UK (Faversham, Kent)	2nd April, 1916	115	700
Germany, Kriewald	26th July, 1921	19	30
France, Miramas	5th August, 1940	0	240
Belgium, Tessenderlo	29th April, 1942	189	150
Texas City, US	16th April, 1947	581	2086+870
Canada, St. Stephen	1947	0	360
Papua New Guinea	2nd Aug, 1994	11	80
China, XingPing	6th Jan, 1998	22	27.6
France, Toulouse	21 Sept, 2001	31	200-300
Spain, Cartagena	Jan 2003	0	-
Romania	24th May, 2004	18	20
Mexico, Monclova	9th Sept, 2007	28	22
USA, West Texas	17th April, 2013	15	240
Australia, Queensland	5th Sept, 2014	0	56
China, Port of Tianjin	12th Aug, 2015	173	800
Lebanon, Beirut	4th Aug, 2020	203	2750

  

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