Hardrock continuous mining

The MX650 - an example for a continuous excavation system

1999
AustriaSweden

Summary

The starting point for the development of the MX650 Rapid Mine Development System was a request by mining companies about ten years ago simply saying: “Just give me a roadheader which can do hard rock cutting.” The currently used point attack tool cutting technology shows clear limitations at ~150MPa UCS in not abrasive rock and at ~70MPa UCS in very abrasive rock. There might be the potential to slightly increase the area of application of point attack tool cutting technology by 10 to 20%, but for real hard rock cutting there is an absolute requirement for new cutting technologies and new hard rock mining machines. So, the company considered the needs of high development speed and of perfect tunnel quality for the development of the MX650. The target is to smoothly and accurately excavate and support tunnels from 4 by 4 meters to 5 by 5 meters at a steady advance rate of 20 meters per day in 150 MPa UCS and very abrasive rock mass conditions. The key operating areas for the MX650 – block and panel caving, narrow reef mining, narrow vein mining and room and pillar mining – show an annual horizontal development need of about 2500 kilometers.

Description

The starting point for the development of the MX650 Rapid Mine Development System was a request by mining companies about ten years ago simply saying: “Just give me a roadheader which can do hard rock cutting.” The currently used point attack tool cutting technology shows clear limitations at ~150MPa UCS in not abrasive rock and at ~70MPa UCS in very abrasive rock. There might be the potential to slightly increase the area of application of point attack tool cutting technology by 10 to 20%, but for real hard rock cutting there is an absolute requirement for new cutting technologies and new hard rock mining machines. So, the company considered the needs of high development speed and of perfect tunnel quality for the development of the MX650. The target is to smoothly and accurately excavate and support tunnels from 4 by 4 meters to 5 by 5 meters at a steady advance rate of 20 meters per day in 150 MPa UCS and very abrasive rock mass conditions. The key operating areas for the MX650 – block and panel caving, narrow reef mining, narrow vein mining and room and pillar mining – show an annual horizontal development need of about 2500 kilometers.
The direct benefit of the use of the MX650 should come from savings in operating costs by less over-break or over excavation, less footwall preparation, less support installation, less tunnel maintenance or rehabilitation and less labor (Including safety benefits) due to integrated systems with high degree of automation. Another and even more significant benefit should be the increase in net present value (NPV) of ore deposits by quicker delivery of development and earlier start of production, the lower infrastructure investment cost by lower tunneling operating costs and the higher ore recovery rate due to better tunnel stability. This is especially the case in block caving, where the development speed has a very high influence on the NPV as about 60% of the scheduled activity is just creating holes in the ground and about 70% of the entire CAPEX is spent prior to any revenue generation.
The assembly and functional testing of the MX650 was completed by end of March 2017, followed by a first test operation at the comany's tungsten mine in Mittersill, Austria, and in the second half of 2017 the MX650 was supposed to operate at Petra Diamond’s Finsch Mine in South Africa.

Impact on the mining value chain

Extraction

  • streamlined permitting procedures
  • reduced grade deposit mining
  • safer and more efficient greater depth extraction
  • increased environmental performance
  • mineral and metallurgical PROCESSING (incl. Permitting)
  • MINE CLOSURE / WASTE management (incl. Permitting)

Mine closure / Waste

  • mining waste reuse/recycling/valorisation
  • waste water management

Other value chain

EXTRACTION (incl. Permitting)
In tunneling within cities, but not mining
EXTRACTION (incl. Permitting)
no chemicals from blasting in the materials
mineral and metallurgical PROCESSING (incl. Permitting)
less waste, better grade control
MINE CLOSURE / WASTE management (incl. Permitting)
less waste
MINE CLOSURE / WASTE management (incl. Permitting)
No chemicals from blasting in the materials

Linked policies

Transferability

It is still too early to say. Improvement of rock stability resulting in less rock support requirements is still open - this will be, besides NPV, a key aspect for the spread of the technology.

Impact area(s): 

Area: 
Environment, Quantity of natural resources
Impact on listed area: 

+:  Higher resource efficiency due to recovery rates from an ore deposit

Area: 
Human/Social, Occupational welfare (health and safety)
Impact on listed area: 

+: The high degree of automation requires less manual handling; less rock stress compared to blasting
-: Unsupported roof of 7m requires requires a certain minimum rock mass stability

Area: 
Economic, Financial flows and profitability
Impact on listed area: 

+: Reduction of costs to the company

Area: 
Economic, Competitiveness
Impact on listed area: 

+: Increased competitiveness due to lower CAPEX

Innovation drivers and barriers
Drivers
Economic
Increased net present value (NPV) of a mine development based on faster advance rates.
Other
Better rock mass quality resulting in less support needs and also resulting in improved safety.
Barriers
Economic
Operating costs: If the improvements in advance rates are not as predicted in the models, this technology will not be competitive to D&B excavation.
Other
Safety: There is a free span length of 7 m between face and first bolt row, which requires a certain minimum rock mass stability.

Good practice areas

Economic sustainability
Increased NPV through faster development; for Sandvik: a new product field
Social responsibility
Safety: high automation means less manual handling

Organisations involved

Innovation category

Process