The 'borehole well' method

This type of solution mining is the most modern and cost-efficient manner of extracting salt. The first step when installing a new borehole well, is to drill a vertical borehole, 30 cm across and several hundred metres deep. This can be done either in the mine using an adit, or from the surface.

Two pipes are then installed in the borehole. One of the pipes is used to inject fresh water into the deepest part of the borehole. The water begins to dissolve the salt deposit and turn the borehole into a brine-filled cavern. The second pipe is used to extract the saturated brine. Compressed air is pressed into the borehole outside the two pipes. This protects the borehole from uncontrolled leaching. At the same time, this 'cushion' of compressed air helps controlling the shape and size of the created brine cavern.

1. Gallery
2. Chamber
3. Double piping system
4. Final shape of the brine cavern