How Does Ice Melt Work?

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November 11, 2020 at 3:45 pm Category: ,

Not every sidewalk, driveway, parking lot or roadway is the same.  There are numerous parameters to consider such as which, when and how to apply ice melt.  This blog takes a look at the question of which ice melt to use in terms of its chemical properties.  

How does ice melt work?

We can all agree that the freezing temperature of snow and ice is 32F.  Ice melt products reduce that freezing temperature.   Most do this by generating heat which in turn physically changes/melts the ice.   The resulting liquid, referred to as brine, maintains its lower freeze point making it easier to manually remove the remaining solid stuff.

The chemicals of the ice melt products determine if heat is needed and if so, how the heat is generated, its lowest working temperature, how corrosive and toxic it is.  The chemicals can be lumped into chlorides and non-chlorides.

Most common chlorides:

Sodium – NaCl
Magnesium – MgCl2
Calcium – CaCl2

Most common non-chlorides:

Potassium Acetate – KAc
Sodium Acetate – NaAc
Potassium Formate  – KF
Sodium Formate – NaF

Effective/working temperature:               

Lowest temp at which an ice melter is cost effective for practical purposes, or where the results/time required to justify the costs. 

Characteristics to Consider Chlorides are mined from the earth. Chloride based ice melts have some inherent challenges and some distinct advantages.  On the challenges side, chlorides are:
  • Corrosive to ferrous metals and can shorten the lifespan of steel infrastructure if not managed carefully
  • Pollutants that can accumulate in water sources and poison the aquatic environment
  • Problematic for many plants
  • Very damaging to concrete by way of more frequent freeze-thaw cycles
On the advantages side, chlorides are:
  • Inexpensive
  • Readily available
Non-Chlorides are manufactured.  They too have some inherent challenges and some distinct advantages.  On the challenges side:
  • Formic acid to make the formate ice melters is imported from Turkey, Sweden, China or India
  • Manufacturing adds to the expense
Advantages:
  • pH levels are closer to neutral rendering them much less corrosive
  • Use less than chlorides
  • Not has harmful to landscaping and bodies of water
To combat the corrosive nature of chlorides, agricultural byproducts will be added.  They will typically be a byproduct of fermented sugars and most will help reduce the freeze temperature.    Generally, these will be proprietary with a branded name.
Deicer Low Temperature Effectiveness Relative Cost Relative Toxicity Environmental Impacts Infrastructure
Chlorides NaCl:15
MgCl2:-5
CaCl2:-15
Low High Accumulates in the environment. Imapcat water quality and aquatic flora and fauna Pavements and metals
Acetates Kac: -26
NaAC: 0
CMA: 0
Moderate Moderate Moderate BOD Pavements and galvanized steel
Formates NaFm: 0
Kfm: -20
High Moderate Moderate BOD Pavements and galvanized steel

Helping to straddle the gap of expense over function, there are many blends of ice melt chemicals.  Read the ingredients label on the bag and the SDS sheet, ask questions and make the best choice.

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