The Makings of Salt

Salt has been used to preserve food and season meals for centuries. Once a highly valuable commodity, salt is now an everyday seasoning and a permanent fixture of most dinner tables around the world. 

But have you ever wondered how salt is produced? 

There are three common methods used around the world to produce salt. The first and oldest method is known as solar evaporation, which involves the evaporation of seawater in shallow pools to leave sea salt crystals. The second method is called solution mining and involves diluting deep subterranean salt deposits into a brine solution which is then pumped to earth’s surface for processing. The third and final common method of salt production involves mining for raw salt minerals through large underground cave-like systems often located thousands of feet into the earth. 

The largest salt mine in the world can be found in Ontario, Canada, where a vast underground mining labyrinth extends over half a kilometre underground. Salt mining involves careful extraction of salt through the room and pillar method. This involves the careful removal of raw salt minerals whilst leaving pillars intact to provide mine support. Traditionally regarded as one of the most dangerous forms of mining, the use of the room and pillar method has dramatically increased salt mining safety, with no record of a salt mine collapse in the last 25 years. 

One type of salt mineral extracted through this method is potash. Potash is a potassium based fertilizer which is used in arable farming to nourish soils and improve crop yields. Potash requires significant processing from its raw form, resulting in a large number of by-products. Some of these by-products, such as table salt, are recoverable and can be further processed. However many less desirable impurities simply end up as waste. 

The New Applications for By-Products of Salt Crystallization Challenge is seeking new and innovative ideas for what can be done with the undesirable by-products of salt production, namely magnesium hydroxide, calcium carbonate, and calcium sulphate. The prize pot for this challenge is $15,000, with solutions not requiring excessive processing of waste products likely to be most successful. Click the link to learn more!