Industrial ammonium nitrate, porous ammonium nitrate, CPAN, PPAN

COMPREHENSIVE UNDERSTANDING OF AMMONIUM NITRATE

On August 4th, a massive explosion occurred in the port area of Beirut, the capital of Lebanon. According to reports, the explosion was caused by welding sparks igniting explosives in a warehouse, resulting in the explosion of ammonium nitrate in another warehouse, causing over 135 deaths. This major explosion incident once again sounded the alarm for us to pay attention to the management of hazardous chemical storage during the high temperature season.

We have compiled relevant knowledge about ammonium nitrate for your reference.

Basic characteristics of ammonium nitrate

Ammonium nitrate, with the chemical formula NH4NO3, is a colorless, odorless, transparent crystal or small white particle with deliquescent properties.

Ammonium nitrate has two main characteristics:

① Easy to dissolve in water, absorbs heat, moisture, and clumps when dissolved in water, and the product is generally made into granules;

② It is prone to thermal decomposition, and the decomposition products vary depending on the temperature.

Pure ammonium nitrate is stable at room temperature and is insensitive to collisions or friction. However, explosions may occur under high temperature, high pressure, the presence of oxidizable substances (reducing agents), and electric sparks. Safety regulations must be strictly followed during production, storage, transportation, and use.

Appearance and characteristics: melting point 169.6 ℃; Boiling point 210 ℃; Relative density (water=1): 1.72; Solubility: Easy to dissolve in water, ethanol, acetone, ammonia water, insoluble in ether. Main uses: Used as analytical reagents, oxidants, refrigerants, fireworks, fertilizers, and explosives.

2. Common uses of ammonium nitrate

Ammonium nitrate is often used to produce high nitrogen fertilizers due to its high nitrogen content. Besides being used as fertilizer, it can also be used as explosives. A chemical industry researcher said, "Ammonium nitrate is mainly used as fertilizer and civilian explosives. Many civilian explosive materials use this chemical raw material because ammonium nitrate is inexpensive, easy to manufacture, and convenient to use

Ammonium nitrate itself is a type of explosive with great power, which can produce a strong explosion when exposed to fire, "said an unnamed chemical industry researcher.

Ammonium nitrate is certainly a type of fertilizer, and it is also a type of explosive, but there is a significant difference between fertilizers and explosives. Ammonium nitrate, used as an explosive, contains a combustion enhancer, while ammonium nitrate, used as a fertilizer, does not have this additive. Therefore, although ammonium nitrate fertilizer can also explode, its detonation difficulty is even more difficult than TNT (trinitrotoluene).

Explosion conditions of ammonium nitrate

Ammonium nitrate is an extremely insensitive explosive and also the most difficult nitrate explosive to detonate. Its impact sensitivity is: a 50kg hammer dropped 50cm high, 0% explosion. However, even under such difficult detonation conditions, its identity as an ammonium nitrate explosive cannot be concealed. In an open environment, a bag of ammonium nitrate will not have such a violent explosion effect when exposed to an open flame. But when many ammonium nitrate piles up, they encounter open flames, high temperatures, and other conditions, and the interior is almost sealed. At this point, if the high temperature and pressure are not released in a timely manner, an explosive effect will occur.

Generally speaking, ammonium nitrate has poor sensitivity to detonation, extremely insensitive to propagation, and completely insensitive to mechanical action. However, it has a fatal danger characteristic - it is not resistant to high temperatures and almost reacts when exposed to open flames.

Data shows that due to the decomposition of ammonium nitrate when exposed to heat, and the faster the reaction at higher temperatures, the reaction becomes extremely violent at temperatures up to 400 degrees Celsius. Therefore, ammonium nitrate is often used as a component of explosive mixtures used in mining, quarrying, and civil construction. This mixture is commonly referred to as ANFO, or fertilizer explosive, and 80% of the explosives used annually in North America are fertilizer explosives.

It is worth noting that if ammonium nitrate is stored for too long and poorly ventilated, it will react and generate heat, leading to an increase in temperature and combustion, and even causing an explosion.

4 Cases of Ammonium Nitrate Explosion Accidents

Explosion accidents caused by ammonium nitrate are not uncommon. Data shows that on April 16, 1947, an industrial accident caused by ammonium nitrate occurred in Texas City, Texas, USA. At that time, a French cargo ship anchored in Galveston Bay caught fire, causing an explosion of about 1996 tons of ammonium nitrate carried on board, which in turn triggered explosions in nearby ships and oil storage facilities. The accident ultimately resulted in at least 581 deaths, with only one survivor from the Texas City fire department involved in the disaster relief. This explosion is also one of the largest non nuclear explosions in human history.

According to the China Emergency Management News, analyzing the 25 hazardous chemical accidents that occurred in August in China's history, there were 19 fire and explosion accidents, accounting for 76% of the total; From the perspective of the occurrence process, there were 9 accidents that occurred in the storage process, accounting for 36%.

It is precisely because ammonium nitrate has enormous destructive power when used as an explosive that many terrorists and extremists often use ammonium nitrate to manufacture explosives. For example, in 1995, the Oklahoma Federal Building in the United States was attacked by a car ammonium nitrate bomb, causing 168 deaths and 680 injuries; In 2011, the government office building and a newspaper in Oslo, Norway were attacked by ammonium nitrate bombs, resulting in 7 deaths and 15 injuries.

5. Relevant standards for ammonium nitrate

GB/T 29879-2013 "Classification Method for Hazardous Characteristics of Ammonium Nitrate Substances" was proposed and managed by the National Technical Committee for Hazardous Chemicals Management Standards (SAC/TC 251). This standard is consistent with the technical content related to ammonium nitrate substances in the United Nations Recommendations on the Transport of Dangerous Goods Model Regulations (16th revised edition) and the United Nations Recommendations on the Transport of Dangerous Goods Manual of Tests and Criteria (5th revised edition).