Sodium bicarbonate is a secondary product of Soda Ash, derived from either natural deposits or man-made.
This product has been derived from natural deposits that are called Trona and are reported to be ancient mineral deposits in the Green River, Wyoming region, 450km below the surface.
The Trona Ore is brought to the surface, refined into slurry containing both Soda Ash and Sodium Bicarbonate.
The crystals and liquid are separated in a centrifuge.
The crystals are then dissolved in a bicarbonate solution and then filtered to remove any non-soluble material.
Purified carbon dioxide is fed into the filtered solution with the resulting reaction forming Sodium Bicarbonate. 

Aluminium Free.

Together with citric acid, bicarb soda is the basic ingredients for making bath bombs and bath fizzies.

In USA recipes, it is called baking soda.