Coal Age

APR 2019

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34 April 2019 highwall management continued to detect and monitor slope-stability changes expressed by surface move- ment. However, microseismic moni- toring techniques can be used to as- sist in characterizing rock/structure disturbances behind the slope before movements on the surface are detect- ed. By integrating microseismic infor- mation with other surface monitoring and modeling results, mine operators can create a reliable assessment tool for slope management and ground control. Microseismic monitoring is widely available as a service package from various providers, with a range of coverage and interpretive options offered. Below are two examples. Mining3 offers a bespoke mi- croseismic continuous-monitoring service to mines with slope-stability issues. Mining3 will design and im- plement the system and offer train- ing to mine geotechnical staff to use and interpret the data. In prac- tice, geophones configured in small arrays are installed in shallow drill holes around slopes of concern. Seismic signals from the geophones are continuously recorded, time- synchronized and transferred via cables and USBs for collection and processing. Both strong and weak mi- croseismic events are measured and assessed to determine their source location, energy and potential impact on slope movement. Mining3, established in 2016, is a partnership between Australia's CRC Mining and CSIRO Mineral Re- sources Group. CRC Mining, which came into being in 1991 as an en- tity in the government's national research center program, brings to- gether Australian and international mining organizations in an effort to develop innovative mining and pro- cessing techniques as well as sup- porting equipment for the industry. Mining3's research and development initiatives are directed by its mining industry members. Mining3 said it also is pursuing development of a system with auto- matic collection and incorporation of high-speed telemetry (e.g., 5G telecommunications) combined with distributed cloud computing and AI technology for rapid monitoring, pro- cessing and interpretation of results in near real time. Ontario, Canada-based ESG also provides microseismic technology for mining and geotechnical applica- tions. According to the company, its complete microseismic systems are easy to use, modular for simple ex- pansion, backward compatible, and operate in a Windows environment. ESG designs and manufactures all hardware and software in-house, including its Paladin data acquisition units, geophones and accelerome- ters. This allows the company to fully customize any microseismic solution to meet specific client needs. ESG does not sell products stand-alone. They are manufactured for use as components of complete microseis- mic systems. The Paladin 5 is the latest, 32-bit version of ESG's digital microseismic recorder, and serves as the backbone of its microseismic data acquisition system. Continuous recording on all stations at once ensures that no data is missed. Unique triggering methods can be configured to record event data based on specific criteria. The Paladin 5 incorporates a re- movable license card that controls the onboard capabilities of the re- corder. Similar in functionality to the legacy Paladin Sensor Interface Box (SIB), the license card comes in two forms. In its basic version, the PIV Daughter Card (PDC) offers a geophone pulse diagnostic test. The more powerful Advanced Diagnos- tics Board (ADB) introduces a wide range of additional features on the PIV, enabling on-board processing and diagnostics capabilities. The ADB is designed to interface with both geophones and acceler- ometers. Lights on the front pan- el indicate channel performance. Advanced diagnostic tools include voltage measurement, sensor auto detect, programmable AC/DC cou- pling, auto detect-correct polarity, and geophone parameter extraction, among other features. Use of the ADB simplifies installation and provides real-time feedback about the health status of the attached sensors. As part of its Hyperion Seismic Software (HSS) suite, ESG offers Seis- Vis, a module that enables advanced 3D-visualization and interpretation of site seismicity using event infor- mation and scaled-site geometries. Event locations, magnitudes, and site velocity profiles, among other param- eters, can be viewed with respect to site geometry or models using a vari- ety of display options. Seismicity can be viewed for specific events or ani- mated over an extended time period using a playback option. The Paladin 5 is the latest, 32-bit version of ESG's digital microseismic recorder, and serves as the backbone of its microseismic data acquisition system.

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