Nat Geo - A fertilizer plant in the community of West, Texas
that exploded on Wednesday to deadly effect was known to produce and
store a volatile and potentially dangerous form of nitrogen-based
fertilizer known as anhydrous ammonia.
Many
fertilizer plants either produce or use anhydrous ammonia—a gas that is
one part nitrogen and three parts hydrogen—as a base for creating
different fertilizer types, said Kurt Steinke, a soil scientist at Michigan State University (MSU).
"Anhydrous
ammonia can be combined with different compounds, such as nitric acid,
sulfuric acid, or even carbon dioxide from the atmosphere to produce the
different kinds of fertilizers that we use today," he said.
Anhydrous
ammonia—often referred to as simply ammonia—can be cheaply manufactured
and is an effective fertilizer in its own right. But producing it
requires intense heat and it must be stored at high pressures.
"When
used in agriculture anhydrous ammonia is compressed into a liquid and
must be stored under high pressure in specially designed tanks. When
the air temperature around the tank increases the temperature of the
liquid inside the tank increases causing the liquid to expand thus
increasing the internal tank pressure," Steinke said. "If you have a
leak in the ammonia tank ... the liquid can quickly convert to a gas
rapidly combining with body moisture to cause severe dehydration and
chemical burns."
