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Road & Sidewalk
Salt FAQs |
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| 1)
What is the difference between sodium chloride and salt? |
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It is the same item. Sodium chloride (NaCl) is the chemical name
for common salt. Back to Top
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2) What advantage does salt have over sand or salt-sand mixtures? |
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The Marquette University Center for Highway and
Traffic Engineering has documented that applying
salt and plowing two-lane roads pays for itself within
25 minutes. Mixtures of salt, cinders or other abrasives
were proven not to recover costs. Not only did these
other abrasives not recover the costs of application
there were additional costs to clean roadways and
catch-basins each spring. Source: 1996 Marquette
University study.
Salt is the most economical deicer. It is readily
available—rock salt is the type most commonly
used though solar salt or evaporated salt may also
be used for deicing. Salt also works best when the
temperature is near freezing. The watery brine formed
by moisture and salt break up the snow and ice so
that roads can be plowed. Municipalities may have
to salt numerous times during large or extended snowstorms
and salt gives the best results and value for the
money spent.
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3) Are there any other advantages to using salt? |
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Salting and plowing help to maintain community
and societal standards.
Emergency and police units are better able to respond
when roads are salted and plowed
Fewer accidents occur on maintained roadways
People are able to go about their daily travels
at or near normal rates
Businesses, schools, and municipalities can operate
Foodstuffs and goods may be delivered to businesses,
preventing disruption of commerce
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4) How does salt work on the
road? |
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As salt is spread over the roadway, it forms a brine (moisture and
salt) as the snow and ice melt. The snow and ice that remain float
on the brine, breaking the bond with the roadway. As more traffic
passes over the surface, slush is formed which can be plowed to
the sides of the road. Plowing alone cannot accomplish this. Salting
and plowing together make safer roadways. The brine's freeze point
is lower than zero and breaks up the bond formed between the road
and the snow. Temperatures, time of application, weather conditions
and the type of road surface, are among the many variables that
can affect the success of deicing. For instance, at 30° F salt
is five times more effective than at 20° F. Back
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5) How does Morton get the salt
to customers? |
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Morton produces bulk road salt year round to meet the winter demands
of our customers. We produce product at six salt mines in North
America along with a solar salt facility in the Bahamas. From these
facilities, salt is shipped and stockpiled in strategic locations
throughout snow belt areas. Our network of mines and stockpiles
is one of the largest in the industry and offers the greatest flexibility
of customer deliveries.
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6) How does Morton get the salt out of the earth?
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There are a number of methods used to produce the salt. Morton Salt
uses solar evaporation, rock salt mining and vacuum pan evaporation.
Solar evaporation is the oldest method of salt production - used
since salt crystals were first noticed in trapped pools of seawater.
Its use is practical only in warm climates where the evaporation
rate exceeds the precipitation rate, either annually or for extended
periods, and ideally, where there are steady prevailing winds.
Solar salt production is, typically, the capturing of salt water
in shallow ponds where the sun evaporates most of the water. The
concentrated brine precipitates the salt which is then gathered
by mechanical harvesting machines. Any impurities that may be present
in the brine are drained off and discarded prior to harvesting.
Morton also uses the second oldest method of producing salt - underground
mining. Large machines travel through vast cave-like passageways
performing various operations. Salt may appear in veins, as does
coal. Veins are the original bedded salt deposits. Salt also may
be found in domes, which were formed when Earth pressures forced
salt up through cracks from depths as great as 30,000 or 40,000
feet. Domes resemble plugs of almost circular shape which are a
few hundred yards to a mile across. Rock salt typically ranges
between 95% and 99% NaCl, and mechanically evaporated salt and
solar salt normally exceed 99% NaCl. Evaporated salt made with
purified brine has the highest purity, in some cases 99.99% NaCl
and is more costly than rock or solar salts. Back
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7) Can table salt melt snow?
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Table salt will melt snow and ice. Table salt grains are fine and
relatively fast-acting. However it would not be cost efficient
for large scale snow melting.
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8) Salt and the Environment
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Proper spreading of road salt, adequate covered storage for salt
stockpiles and pre-wetting salt with salt brine have combined to
make salting of roads the most cost-effective and safest method
for snow and ice control.
Improved spreading equipment and proper
calibration can ensure that only the minimum amount of salt is
used for the job. Proper salting procedures and techniques are
covered in "The Snow Fighter's Handbook" published by the Salt
Institute. In addition, the Institute offers Sensible Salting training
to public works agencies.
Adequate covered storage of salt stockpiles
and placement on non-permeable pads are necessary to limit run
off into the environment. Non-permeable covers are used to cover
the Morton Salt network of stockpiles used for customer deliveries.
Morton Salt also uses asphalt or concrete pads at the stockpiles.
A relatively new development in salting is the use of pre-wetting
salt brine to moisten the salt at application. Studies have shown
that pre-wetting salt reduces salt scatter on the roads by 15 to
30 percent. (Michigan DOT, "1974-5 Pre-wetted Salt Report', June
1, 1975). Pre-wetting with salt brine can reduce the chlorides
released into the environment by 14-29 percent. (Asset Insight
Technologies, LLC, "Review of Two Documents Pertaining to Chloride
Reduction and Cost Savings Resulting from the Use of Pre-wetting
in Winter Maintenance", Dr. Wilfrid A. Nixon, March 24, 2003. Back
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