Focus of activities

How to make the underground cavaties stable and long-lasting?

Kali-Umwelttechnik GmbH was given the task by the relevant mining authority to examine and report on the condition of a potassium dig in the North Harz-Revier which had been closed down in 1949, and to recommend an appropriate redevelopment concept in order to avert any potential danger.It emerged that both shafts showed severe ruin from decades of aggressive running shaft water. Hence there is fear of the shafts collapsing.

Evidence of erosion through water

The following methods were applied in order to explore the condition of the two shafts and the mine:

• Physical examination of the shaft with regard to the stability shaft head structures.
• Borehole camera to document the conditions of the shafts

Photographs of the mine shaft with a borehole camera

• Exploration drilling
• Geophysics to explore the area: Electrical resistance and surface radar
• Borehole-radar and borehole-sonar in the exploration holes drilled

Introduction of radar probes in a borehole

• Discovery of geological weak points
• Installation of geomechanical surveillance equipment

Convergence measuring

• Installation of measuring equipment to observe the alkaline solution

As a result of the exploration results, recommendations could be made as to where, when and what needs to be done in order to guarantee the safety of the mine.

In order to avoid what was established as an acutely dangerous situation, a concept of redevelopment of the damaged area was worked on and realized. A new and patented method developed by K-UTEC was used on both shafts. This method consists of using a mineral based building material with plastic properties to stabilize loose formations.

Experimental bodies for filling material

The building material was prepared in K-UTEC's own facility and transported to the site. The facility can mix up to 10 m³/hr.

Schematic portrayal of filled column		Erecting of the mixing plant for filling material

With the afore-mentioned methods, the potential for danger in the shaft and on the surface could be reduced to a minimum and the long term stability of the shaft head structure was assured.