system
Given the following post, respond as if you're commenting on Reddit:
human
Using freezing point depression how does adding salt to ice (0 C) reduce the temp (to <0 C)? or does it?

I understand how freezing point depression works with the salt ions disrupting ice crystal lattice formation. However, when I'm looking at pages for homemade ice cream they say that adding salt allows for the mixture to be below the freezing point of water. 
While I can see that adding salt to the ice will melt some of the ice and water will allow for more heat transfer from the cream to the brine (than just ice alone), I don't see how the temperature can be reduced below 0 C. There is nothing colder around it to remove heat from the mixture and everything around it is warmer and will be adding heat to the brine.  
How does the brine become colder than 0 C?
gpt
When you add salt and lower the freezing temperature of the solution, ice will begin to melt because it's then above the freezing temperature. However, ice requires a lot of energy when it melts, which it will take from it's surroundings and therefor decrease the overall temperature.