Salt Production: Rock Mining

What is rock salt and where does it come from?

Rock salt, or halite, is a naturally occurring form of sodium chloride (NaCl), formed millions of years ago through the evaporation of prehistoric seas and lagoons. As these salt-rich bodies of water dried up, thick layers of salt were left behind and gradually buried under sediment and rock formations.

Today, these underground salt deposits are found deep beneath the Earth’s surface or within mountain ranges and are mined using various extraction methods. Rock salt is typically found in large, stable formations, making it ideal for industrial-scale mining.

This method is especially relevant in inland regions where salt cannot be harvested from seawater through solar evaporation. It plays a vital role in the global salt supply, accounting for a significant portion of total production—about 30% in Europe—with major producers located in countries like Germany, the United Kingdom, USA and China.

How is rock salt extracted?

There are two primary techniques for mining rock salt underground:

1. Cut and blast mining

In this method, long slots are cut at the base of the salt wall. Then, holes are drilled and filled with explosives. When detonated, the blast breaks the salt into large chunks, which are collected and later crushed into smaller, manageable pieces. This method is efficient and suited for thick, uniform salt beds.

2. Continuous mining

This process uses specialized machines—similar to those used for tunnel construction—that bore directly into the salt face. The machine grinds the salt into small lumps while advancing through the deposit, offering a faster, more consistent extraction method without the need for explosives.

In both approaches, mine stability and worker safety are top priorities. Pillars of untouched salt are strategically left in place to support the roof of the mine, ensuring structural integrity throughout the operation.

From extraction to application

Once the salt is brought to the surface, it typically undergoes crushing, screening, and sometimes washing, depending on its intended use. While some of the mined salt is refined further for human consumption, much of it is used in:

• De-icing roads during winter
• Water treatment and softening
• Chemical manufacturing
• Animal nutrition and feed supplements

Rock salt’s natural purity, availability in large volumes, and broad range of applications make it an essential resource for modern infrastructure and industry.