How Is Salt Made? - Dirt-to-Dinner

Today, you would be hard-pressed to find a household without a salt shaker, but this wasn’t always the case. Salt was scarce until the industrial revolution provided the technology to discover vast salt reserves. Salt was once used as a currency as valuable as gold – traded and fought over worldwide.

“For millennia, salt represented wealth. Caribbean salt merchants stockpiled it in the basements of their homes. The Chinese, the Romans, the French, the Venetians, the Habsburgs, and numerous other governments taxed it to raise money for wars.”

Salt: A World History, Mark Kurlansky

Salt’s wide applications

Salt is used in thousands of ways all around the world. It is a jack of all trades that can enhance the flavor of foods in your kitchen and assist in manufacturing paper, plastics, and fertilizers. Its preservative and antimicrobial effects are significant in the food processing industry, and it has a vital role in feeding animals and plants.

The U.S. and China dominate world salt production, accounting for 40% of the 250 million tons of salt produced yearly. Kansas, Louisiana, Michigan, New York, Ohio, Texas, and Utah made 92% of the salt in the United States in 2019. In fact, Detroit sits on one of the largest salt deposits in the world, and most of the salt used for de-icing our roadways is mined from an ancient seabed near Cleveland, 2,000 feet below Lake Erie.

Salt production methods

Whether salt is mined from ancient sea beds under the city of Detroit, the Appalachian Mountains, or the Himalayan Mountains; extracted from salt domes along the Louisiana coastline, or solar evaporated from the Atlantic or Pacific oceans – all salt comes from the sea!

But what happens next? It depends on the application and location:

• Deep-Shaft Mining: Like mining for any other mineral, salt exists as deposits in underground ancient sea beds, typically miles long and thousands of feet deep. Most “rock salt” (used to de-ice highways and walkways) is produced this way. Take a look at this video.
• Solution Mining: Wells, similar to oil and gas wells, are set up over salt deposits, and fresh water is injected to dissolve the salt. The brine is then pumped out and taken to a plant for evaporation.
• Solar Evaporation: The oldest salt production method in warmer climates, salt is first captured in shallow ponds, where the wind and sun evaporate the water. The salt is then harvested either by hand or by machine.

Watch the below video that demonstrates harvesting evaporated salt in California.