While achieving longwall automation is the obvious long-term objective, the project’s steering committee is looking to deliver early benefits to longwall mines. These will include developing solutions for controlling face cutting horizon and alignment, and making sensor technology more reliable.
Being able to deliver outcomes that will benefit the majority of longwall operations, not just those with the most recent technology, is one of the most important objectives to emerge from the scoping study. It is an important point and one that underlines the commitment of the project’s Longwall Automation Steering Committee (LASC) to benefit the wider community of longwall operations.
“We want to focus on improving operating systems, reliability, and control technology that can be passed onto people with older equipment so they can start to operate roof supports at their optimum capacity. Ensuring they are putting the right amount of support into the roof, especially higher tip loads, will deliver better face conditions,” said LASC chairman, BHP manager underground, Guy Mitchell.
The initial phase of the scoping study included industry-wide consultations and discussions with OEMs, various research organisations, including the CSIRO and CMTE, mining operations and companies, and consultants.
Mitchell said one of the key issues raised by industry is that data transmission and related sensor technology and valves is either inadequate or unreliable. As Mitchell points out, if the sensor technology is not more reliable, automation – which depends on accurate data input - is doomed to fail.
“If we can improve the reliability and availability of those basic components, even if there is no longwall automation – by making the hydraulic capabilities and control of the supports more reliable, placing designed support loads into the roof, ensuring the shearer is cutting the right web thickness for a specific time and place on the face, and the supports move when they are supposed to – this will all translate into better face conditions and therefore improved mining rates.”
Of the 11 objectives (see full list of objectives in Table 1), improved horizon control is seen by LASC as a critical short-term objective. By focusing on rapid delivery of early wins, the project will be assured of ongoing support from the industry. There is an awareness, however, that concentrating on short-term issues for quick gain must be balanced against the need to maintain sufficient funding and momentum to achieve the long-term project goals.
According to LASC, while horizon control currently exists in some forms, these are usually “memory cut” or preprogrammed cycles. True horizon control should be able to recognise changing gradients and other features that require a change in the cutting height. This will require the development of a reliable method of "seeing" the coal-roof-floor interfaces. Methods such as gamma ray and ground seeking radar are possibilities. Some form of roof void detection will also be important.
Achieving this will require the development of an intelligent data acquisition and control mechanism, capable of accepting preprogrammed information from known geological features of the coal and roof/floor structures. It will also collect data on gas, ventilation, mining methods and dynamic operational data from the area such as coal clearance. What will make this a true horizon controlled and face aligned system will be its ability to guide the longwall through the block by flagging what will happen on the next cut.
The result of these discussions has been the development of a vision statement, definition of automation, and project objectives (shown in Table 1).
LASC’s vision is to achieve "a longwall face that will operate automatically within pre-defined parameters to enhance health and safety, production consistency, lower operating costs and improve return on capital."
Within the project scope, the definition of an automated system is
- one which carries out routine functions such as cutting and loading coal, maintaining face alignment, and moving and setting roof supports within pre-defined operating boundaries and without human intervention.
- Such a longwall system would monitor itself and the surrounding environment to provide for self-diagnosis of system health and indications of approached to and departures from the pre-defined operating boundaries.
- Finally, the system would initiate requests for human intervention based on approaches to and departures from the pre-defined operating boundary conditions.
In terms of allocating work and moving to the next phase of the project the LASC committee is now in the process of determining which organisation/s have the best expertise to investigate, develop and possibly research various facets. It has been agreed that both the CSIRO and CMTE have a role to play, though exactly which organisation will tackle which aspect of the research is still under discussion.
LASC includes chairman Mitchell, Paul Harrington (MIM Newlands), Tony Singleton (Anglo Coal), Steve Allenby (COAL, Ingwe), Peter Henderson and Jim Sandford (Bulga, Glencore) and independent consultant Ray Dubois as longwall automation project co-ordinator.
Mitchell said that the OEM’s in Australia, and in some cases the United States, have made very positive comments on the value of the project and have indicated a willingness to be involved. In December 2000, the main OEM’s are being invited to a LASC meeting with both CSIRO and CMTE to begin exploring ways for these organisations to be involved in the second phase of this scoping study.
LASC is due to report its findings and recommendations to the ACARP Research Sub-Committee and the ACR Board by May 2001.
