NAVIGATION technology adapted from the aerospace and land military industries to mining continues to provide a reliable means of underground machine control and guidance, according to the Brisbane-based Cooperative Research Centre for Mining Technology & Equipment.

The HORTA (Honeywell Ore Recovery and Tunnelling Aid) system has now been installed and is fully operational on several highwall coal mining systems in New South Wales and Queensland, operated by Roche Highwall Mining and BHP Coal. Dr David Hainsworth from the CSIRO Division of Exploration and Mining, and the CMTE’s principal investigator for the HORTA project, said the system made more precise mine planning possible.

“The net effect of the system is a safer and more productive operation with a significant increase in recovery rates,” he said. “This installation was the first in the world to give the operator continuous readings of the pillar thickness to the previous drive.”

RHM research engineer Dr David Reid, part of the original CMTE research team, said the performance of the guidance system had “exceeded project expectations” and hardware and software used had proved to be exceptionally robust and reliable.

“The guidance system has allowed world record highwall penetration depths — consistently over 500m — thus increasing the resource recovery percentage,” he said.

At the Ulan coal mine near Mudgee, NSW, a combination of mildly dipping seams and stable ground conditions has enabled RHM to consistently mine more than 100,000t of coal per month. The contractor plans to extract lower-grade domestic market coal from the upper levels of the Ulan seam using what is known as the “stacked upper pass” technique. Upper and lower level seams are separated vertically by a 3m rock septum. Once the upper level seam is mined, a second pass is used to mine the lower level seam. The technique enables the highwall miner to access economic-grade plys within a generally low-grade section of the coal seam.

“This double pass mining is only possible because of the guidance system,” Dr Reid said. “The guidance system software has been enhanced to provide the highwall mining operator with information about how the lower pass drives align with the upper pass drives.

“For those highwall mining systems using the guidance technology it has become such an important and integral component of the operations that it is now deemed unsafe to mine without it.”

Dr Reid said other local and international highwall mining operators had enquired about purchasing the guidance system. The existing prototype is the focus of further development, including software enhancement, for release as a full commercial product.