Underground » Roadway Development
Despite attempts to introduce continuous haulage systems into Australian coal mines since the late-1980s, shuttle cars remain the primary method of coal clearance from face to panel conveyor in bord and pillar operations and longwall gateroad development. Such batch coal haulage systems have a relatively large cross-sectional area with respect to the roadway cross-sectional area. A recent study completed as part of ACARP Project C17018 (Automated Installation of Bolts and Mesh) demonstrated the incompatibility, impracticability and inability of supplying materials to the face and sustaining the rate of advance contemplated within ACARP's CM2010 Roadway Development Improvement Strategy (10 MPOH, 20 hours per day) if batch coal haulage systems continue to be adopted for gateroad development.
The C21025 project was subsequently developed at the request of ACARP's Roadway Development Task Group (RDTG) to research and identify the range of continuous haulage systems and related technologies that are either currently available for application, or are currently under research and development or concept design. The objective of the project is to understand which system or systems provide or can provide the greatest potential to meet the functional requirements of a continuous haulage system and allow simultaneous operation of all longwall gateroad development activities.
Major benefits arising from the prospective development of a small profile, continuous coal clearance system that meets the 10 MPOH target and enables an integrated strata support materials handling system to be employed are considered to include:
· Increased compatibility of coal clearance and strata support material logistics functions;
· Increased capacity and productivity, including reduced cost per metre advance;
· Minimal deterioration of floor conditions otherwise arising from repeated shuttle car movements;
· Increased safety for mine personnel, such as reduced manual handling and machine-human interactions;
· Reduced operator exposure to whole body vibration; and
· Elimination of shuttle car cable damage and maintenance.
The scope of the project included an assessment of the identified systems and technologies, an intellectual property review to identify any new technologies and whether there were any IP issues relating to the identified technologies that may impact or could preclude their introduction to the underground coal sector, and a regulatory review to identify potential legislative barriers that would need to be considered for the introduction of the identified systems or concepts in this sector.
While there are no continuous haulage systems currently being utilised in longwall gateroad development other than rigid, fixed length, monorail mounted systems being used in Siberian mines, some 15 different conveying/transportation technologies were identified either from earlier or current research projects, or from bord and pillar operations. The opportunity was taken to: inspect both the Joy 4FCT and Prairie Flexiveyor continuous haulage systems in operation at Clarence and Cook Colliery, respectively; inspect conveying technologies being employed in other industry sectors; and also meet directly with OEM representatives and researchers. An IP search based on underground conveying and transportation systems and known OEMs operating in the underground mining sector also identified 168 patents of which a number have some relevance to the continuous haulage system contemplated by the RDTG.
Of the 15 technologies identified two were discounted from the analysis on the basis of known unacceptable performance capabilities and characteristics (e.g. pneumatic and slurry/ hydraulic conveying systems), two were discounted due to the lack of relevant information while the Joy 2FCT was discounted due to Joy's insistence that the roof mounted system had been superseded by the 4FCT.
Fatal flaws were identified during the analysis with respect to the application of conventional mobile bridge conveyors in gateroad development, as was the application of conventional pipe or tube conveyors.
Areas of concern (in the context of the specified project objectives) were raised with regards to the physical size of the 4FCT and its relative difficulty to properly track through the roadway and cut-throughs. Such factors were expected to make integration of the 4FCT and materials resupply problematic.
Five systems/technologies were subsequently submitted to a second round of evaluations as a part of the study with OEMs invited to respond to detailed interim findings made in regards to their respective systems (e.g. ACE/Bosmin Co-axial Pipe (CAP) Conveyor, Premron Enerka-Becker System (E-BS), Innovative Conveying Systems International (ICS), Sandvik VACHS 500 and DMS/Prairie's Narrow Development Flexiveyor).