AMC Consultants is proud to contribute to the Underground Operators Conference 2021 with a technical presentation. The conference is organized by the AusIMM‘ and will take place in Perth and online 15-17 March 2021.
AMC’s Ruth Stephenson (Director/Geotechnical Manager, Perth) and Mike Sandy (Principal Geotechnical Engineer, Practice Leader – Geotechnical) will present the paper “Considerations for the design and support of underground portals” in the afternoon of Day 2 of the conference.
The conference brings together suppliers, engineers and operators from the underground mining industry both from locally and internationally to share their stories of both success and challenges at their operations.
PRESENTATION: Considerations for the design and support of underground portals
SESSION 8: Innovative mining methods and practices IV
Time: 3:40-5:15 PM
Date: Tuesday 16 March 2021
Venue: Riverside Theatre
Portals to access underground mines are important infrastructure and their design requires careful consideration. Portals are generally expected to last for the life of the mine.Typically, the exposure of personnel and equipment is high, with many hundreds of movements through the portal per day. Consequently, the hazard associated with geotechnical instability must be extremely low.
Portals are often established from a boxcut. In areas where the weathering profile is well developed, the design and execution of the boxcut can involve significant effort, with the objective of minimizing the volume of the boxcut, whilst ensuring that conditions at the design depth are suitable for establishing a stable portal. Properly designed site investigations are a critical part of this process.
Currently available portal design guidelines have not been updated for decades, however the equipment and ground support systems have changed significantly in recent years. Many mine portals have since been constructed in a relatively short time frame with success, often in challenging ground conditions using some of the more modern approaches to ground support. This is beneficial because delays in establishing a portal will generally delay other critical path activities, and lead to cost overruns.
RAFFLE: Private executive summary presentation of strategy optimization
We invite delegates to visit us at booth 97 to enter our raffle. The winning prize will be a rare two-hour executive summary presentation on strategy optimization with AMC’s Brian Hall, the creator of the Hill of Value process. The private presentation and subsequent Q&A session will be for up to ten members of the winning company’s management team and will include ten digital copies of Brian’s seminal work “Cut-off Grades and Optimising the Strategic Mine Plan” published by the AusIMM.
Principal Mining Engineer
Brian Hall is an internationally recognized leader in optimization of mine plans and strategies for underground and surface mines. With almost five decades of experience in the mining industry, he is a sought-after advisor and speaker on the topic.
Since coining the term Hill of Value 20 years ago, Brian has specialized in the optimization of cut-off grades and strategic mine plans. He presents workshops on project evaluation, the theory and practical application of cut-off grades, and mine and business strategy optimization. He authored the authoritative textbook, Cut-off Grades and Optimising the Strategic Mine Plan, published by the AusIMM in 2014.
Brian is also a sessional lecturer at Curtin University in Perth, where he presents a unit in the Master of Mineral and Energy Economics programme at the Curtin Graduate School of Business three times a year.
About the presenters:
Director/Geotechnical Manager, Perth
Ruth is a geotechnical engineer more than 17 years of experience in geotechnical engineering. Ruth joined AMC eight years ago following nine years of practical experience across several operations in Western Australia, predominantly at underground sub-level open stoping operations.
Since joining AMC in August 2012 Ruth has worked on raise bore assessments, geotechnical reviews, and feasibility studies for underground and open-pit operations in Australia, Russia, Italy, Canada, Tanzania, Ghana, Eritrea, Indonesia, Fiji, Philippines, New Zealand and Argentina. She has provided geotechnical training to operations in Australia and Tanzania with a strong focus on geotechnical risk management. In December 2017, Ruth was promoted to Geotechnical Manager at AMC’s office in Perth.
Principal Geotechnical Engineer, Practice Leader – Geotechnical
Mike is a geotechnical engineer with more than 40 years of mining industry experience. His primary expertise is in rock mechanics (underground operations) including ground support design, rock mass characterization, mining method selection and optimization, extraction sequencing and applied numerical modelling.
Mike also has extensive experience in underground mine planning and feasibility studies, mine geology, dewatering, diamond drilling strategies and management of mining technical research.
Mike has travelled extensively in his career, including for reviews of mining projects in Canada, Ireland, Sweden, Chile, China, Indonesia, the Philippines, Turkey, South Africa, Zambia, Tanzania, Mauritania, Ghana, Russia, and the USA. He has conducted rock mechanics and mine design reviews of several large-scale open stoping operations – for example, Olympic Dam, Mt Isa – 3500 Orebody and George Fisher, St Ives Gold Mines and Mindola. Caving studies have included Big Bell (SLC), SOB Synclinorium Nkana (Mopani, SLC), Northparkes – Lift 2 (block caving), Argyle Mudrush Potential (BC and SLC), Didipio (BC/SLC), Akwaaba (SLC) and Afton (BC). High level reviews have been conducted of Bingham Canyon (BC), Resolution (BC), Oyu Tolgoi and Grasberg Block Cave.
Establishing effective geotechnical processes for UG mines
Effective mine designs require collaborative efforts between geology, mine planning, mine production, and geotechnical engineering groups. The cycle of design, execution, measurement, and feedback should be continuous. Employing a well-documented and standardized approach is essential to ensuring a coherent, consistent and efficient system.
Trends in Australian Underground Mining Costs
Underground mining costs have increased over the years, but it is difficult to quantify the increase because they also vary according to mining rate and the mining method, particularly where cemented backfill is used. AMC has recently completed an analysis covering the period 1980 to 2016, using data from 82 Australian mines. All mines used drill and blast methods.