Fun facts
Potassium Nitrate's nickname, Salt Petre is derived from the Latin words sal patrae, which means “salt of the rock,”
In the United States, over 200,000 tons of potassium nitrate is manufactured per year, with over 90% of it being used in fertilizers. Worldwide, over 30 million is extracted annually, with Russia the leading producer with over half of the annual total.
Process
Originally, potassium nitrate and other components of gunpowder were mixed through crushing them together using a wooden stamp. However, that was soon changed with the invention of the metal stamp. Presently, charcoal and sulfur are mixed using spheres of metal rotating within cylinders. Potassium nitrate is prepared separately, and the components are then combined. It is crushed into cakes of powder, and then separated into smaller pieces, before being tumbled in wooden barrels to smooth rough edges. Finally, graphite is introduced to create a coating powder.