DynaCut Fundamental Development and Scalability Testing

The primary aim of this project was to validate the performance of the DynaCut rock cutting technology in representative overburden materials, to de-risk further work towards an up-scaled high capacity overburden mining system. A secondary component aimed to investigate new mining approaches and designs to exploit the advantages of a continuous mining system utilising the DynaCut technology. This element will ultimately assist mine operators to understand the potential implementation opportunities presented by this technology.

Joy's DynaCut test machine was used for cutting trials at a sandstone quarry. This provided representative rock domains - low-strength (<30 MPa UCS), medium-strength (~30-50 MPa UCS), higher-strength (+50/60 MPa UCS) - to collect cutting data for estimations of cost and cutting rates for an up-scaled system.

Noise, dust and vibration during cutting were not atypical of general mining equipment. The cutting mechanism inherently creates minimal fines during operation, far less than pick-based cutting tools. Occasional blocks dislodged from the face, where clear discontinuities were present. Cuttings were typically plate-like in shape, with material swell not abnormal for loosely-piled material at about 33%. The cutters performed very well, with very low cutter wear rates.

There was a general trend of increasing specific energy of cutting (SE) with increasing material strength. The SE ranged from about 1.0 MJ/m3 to 6.9 MJ/m3, averaging between about 3.5 MJ/m3 and 3.8 MJ/m3 across the three rock domains. The instantaneous cutting rate (ICR) ranged from about 35 m3/hr to 120 m3/hr. The ICR and SE varied significantly within each rock domain, due to rock mass properties controlling the cuttability - in particular, discontinuities that assisted fracture propagation and facilitated chip or block generation during cutting.

Cutting rate and cost estimates from the previous project phase were generally well supported by the new data. Refined estimates, based on the new data, indicate slightly flatter cost and rate curves than anticipated, with higher performance (higher cut rate and lower cost than expected) in the higher-strength material. Indicative average cutting costs for material across the three domains tested are around $2.00 to $2.50 per BCM for an up-scaled machine. Further improvement of overall system performance and operating costs are expected through continued refinements to machine operating parameters and cutter designs.

Various concepts for new mining methods and approaches were developed, with context provided by classification of typical coal deposit settings and key functional requirements. Three shortlisted concepts were applied to a specific mining scenario and assessed on the basis of indicative cost and key risk factors.