How ionization of salt takes place in salt mines? and
How salt gets in air in salt caves or mines?
As you probably know, ionization of minerals is caused by water. Add salt to water and you end up with disassociated sodium and chloride ions in an aqueous solution. This occurs due to the effects of the Hydrogen and Oxygen molecules in the water. Electrons are donated to the sodium chloride compound which breaks up the bond holding the two elements together.
Anyway, something similar happens in the humid, damp atmosphere of the mine. Mines are notoriously damp and wet. The earth itself is subjected to what we call earth tides. The same gravitational effect that the Moon has on the oceans also occur on the solid earth itself.
When doing research looking into the use of various gases found in association with petroleum reservoirs, we looked at Helium an inert gas. We found that when sampling the soil for Helium, we saw that the Earth tides had an effect on the concentrations we saw. They correlated with the stages of the Lunar tides. So in effect the Moon's gravitational pull acted as a sort of "pump" squeezing and releasing the solid Earth pumping gases from the ground below. These are small quantities to be sure, but it was real none the less.
So if you think about a mine, water is moving through the salt deposits in the mine, doing its thing by ionizing the mineral. These minerals evaporate into the air along with the moisture creating the humidity in the mine itself. So the air is laden with salt laden moisture. Just as when you park your car near the beach in a storm, salt from the air is deposited on your windshield even If you are parked far enough away that sea water did not splash on it. Disassociated ionized molecules are being transported by the water content of the air itself, and when it touches a cool surface condenses and is deposited. The two molecules, Na and Cl then rebond to become salt. The same thing happens when you breath in the molecules in the atmosphere in a mine, they rebond on you tongue and you can taste salt.
Now the preponderance of negative Ions in the atmosphere of the mine or near the sea shore, or after a rain, tend to cleanse the atmosphere of pollutants and give the air a fresh smell and taste. This is purported to have health effects. There are artificial devices the ionize the air, I have one in my bedroom to cleanse the air of allergens. They are also said to counter the positive electrons, or ozone given off by electronic devices. With new flat screen monitors, it is not as big of a problem as it used to be, when we all sat in front of cathode ray tubes, the old big monitors. Recall the static electricity they gave off when you touched them? Sitting in front of them for hours tended to make one feel tense and restless and was said to create a number of health problems. New flat screens do not generate the positive electrons that the old CRTs did.