The action is by oxygen and water on a clean surface. It is our policy to passivate the SUS 316L and SUS 316LN austenitic SS tanks with 14% by volume cold Nitric acid. It is also our policy not to include hydrofluoric acid in a passivation solution. Hydro-flouric acid is a pickler which removes chromium and nickel along with heat hardened scale, it NOT a passivator. The concentrated acid you get on board in 200 litre drums is usually 68%. Contact time for Nitric acid is 2 hours.
Mineral salts can come in varieties. They are inorganic salts and include phosphate, calcium, chloride, sodium and potassium. One of the most common mineral salts is iodized salt. Iodine is essential to the function of the body as an iodine deficiency can be problematic.
All major rock salt deposits originated from the evaporation of seawater at some time during the geologic past. Approximately 78 percent of the mineral matter in normal seawater is sodium chloride. Upon evaporation of about nine-tenths of the volume of seawater, rock salt is precipitated. Calcium sulfate (gypsum and anhydrite) and potassium and magnesium salts also are precipitated.