Current methods of mechanical excavation of rock are limited in regard to the material which can be extracted economically. The use of roadheaders with pick tools has the advantage of high flexibility in form of turn off radii down to 1 m but is limited by rock strength to figures below 150 MPa UCS.
While mechanical rock excavation machines with disc cutters can handle rock strengths above 150 MPa, they are limited to turn off radii >12 m. This issue is discussed in detail and shown in this paper.
Therefore there is presently a significant “Gap” for a method (other than drill & blast) of rock extraction for turn off radii below 12 m and rock strengths above 150 MPa UCS.
This gives the motivation of R&D into alternative extraction methods which could lead to new combined methods covering this “Gap”.
Please find more information in the enclosed publication in Berg- und Hüttenmännische Monatshefte 162(2), 2017.