Understanding nucleation of salt deposits (mixing waters)

[rwooduk]

I am trying to understand the nucleation process of salt deposits, if someone here could give me a point in the right direction it would be really appreciated.

I read that if you have a water rich in sulfates, and mix with a water rich in barium ions, calcium ions or strontium ions, that a seed can be formed for nucleation of salt deposits (scaling). This occurs when sea water is pumped into an oil well and mixes with the formation water (rock water) of the reservoir. The article says, "deposits result from supersaturation where unstable atoms tend to join". What does it mean by unstable atoms? Where does the energy (if there is such a thing) for the nucleation come from? Since there is formation of a solid does this indicate some sort of precipitation reaction?

If anyone is familiar with the chemistry that might be occurring in this process, it would be very useful to have their opinion on this.

Thanks in advance for any help.

 

[Borek]

Every nucleation requires some activation energy - and it can come from any typical source (like any local fluctuation in temperature or pressure).

I suppose by "unstable" they mean excess that has to be removed for the system to get to the equilibrium (if it is oversaturated, it is not there).

 

[rwooduk]

Every nucleation requires some activation energy - and it can come from any typical source (like any local fluctuation in temperature or pressure).

I suppose by "unstable" they mean excess that has to be removed for the system to get to the equilibrium (if it is oversaturated, it is not there).

Thank you Borek for that interpretation it is very helpful.