Fire or Explosion Concerns:
While lime can generate heat if exposed to moisture, it
is not in itself combustible, and therefore presents a low
f re risk.
What is the Coast Guard doing about it?
The U.S. Coast Guard ensures compliance with the
domestic and international regulations applicable to
lime bulk transport in U.S. waters.
About the author:
Mr. Tom Gleave is a chemical engineer in the Hazardous Materials
Division at U.S. Coast Guard headquarters. He develops, maintains,
and updates domestic and international regulations for solid bulk cargo
marine transport. Mr. Gleave earned a B.S. in environmental engineering
from Temple University and has more than a decade of experience in envi-
ronmental engineering and air quality compliance. He also served four
years in the U.S. Navy as an aviation electricians' mate.
Lewis, Richard J. Sr. "Calcium Oxide." Hawley's Condensed Chemical Dictionary,
The National Lime Association. NLA, 3 November 2014. Available at www.lime.
"Lime: Calcium Oxide — CAO." Chemical of the Week. Scifun.org, 20 October 2014.
Available at http://scifun.chem.wisc.edu/chemweek/lime/lime.html.
CAMEO Chemicals, "Calcium Oxide." NOAA, 13 October 2014. Available at http://
What is it?
Unslaked lime is an inorganic white or grayish-white
odorless crystalline solid that is soluble in acid and reacts
exothermically with water to form calcium hydroxide.
Lime has a wide variety of uses and applications that
make it quite valuable, including steel manufacturing,
environmental protection, construction, mining, and
In steel manufacturing, it is used as a f ux to remove
impurities such as silica, phosphorus, and sulfur from
molten iron. The fastest-growing and second most com-
mon use is in environmental protection, where lime is
used to remove sulfur oxides and mercury from power
plant emissions. It is also used to treat sewage sludge
and animal waste from feeding operations and to adjust
pH in industrial waste water discharges.
Why should I care?
When unslaked lime combines with water, it generates a
great amount of heat that may ignite nearby combustible
materials, so it should be stored away from paint, vessel
stores, or other combustible solids/cargoes.
Lime is corrosive to the eyes and mucus membranes. It
can also cause serious alkali burns on the skin or inter-
nally, if inhaled or swallowed.
Understanding Unslaked Lime
by Mr. toM glEAvE
Hazardous Materials Division
U.S. Coast Guard
Proceedings Fall 2015