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Underground Mine Planning 

 

Summary

This review describes the different aspects of underground mine planning and design. It gives several links to underground mine design publications, courses, software, contractors, and consultants.

UNDERGROUND MINE PLANNING IN BRIEF

At its simplest, underground mine planning involves coming up with the optimum layout for the underground workings that get at most of the ore, at the lowest cost, and with the greatest safety.

Thus you need to know where the ore is, what the rocks are that you will have to go through to get to it, how much ground water may flow in to bedevil your advance, how to support the rock roof lest it fall down on you, how to get air in and out of the workings, and how best to move men and materials around safely and cost-effectively.

Underground mine planning is a multi-disciplinary activity. The geologist tells about the rocks and the ore body. The hydrologist tells about the groundwater. The mining engineer will usually be the one who lays out the actual shaft, stopes and associated workings. A good ventilation engineer is crucial. And many mechanical engineers to select, install, and keep the equipment working. It also helps to have a good rock mechanics expert to tell about pillar layout and rock support.

Thus it is that you seldom find one person who can do it all. Generally you will need to get a consultant, their team, and an experienced project manager to bring it all together. And while putting this team together, do not neglect to get a good economist and cost estimator on board. No point in having the perfect design that is uneconomic.


STAGES IN UNDERGROUND MINE PLANNING

The mine plan represents the phase of mine's life from the initiation of feasibility study to production. The process of mine planning generally consists of the following stages:

1. Feasibility Stage
This is first stage in mine planning with the whole purpose of determining the techno-economic limits of extracting ore from the ore body.

2. Design optimisation
After it is concluded form the feasibility stage that the project is feasible, the next stage involved is creating and optimising a design to access the ore body.

3. Design Scheduling
The next stage involves scheduling the design both on long term and short term basis. The design scheduling is usually done by manual approximations or/and analytical computer techniques.

4. Production Scheduling
This is the final targeted stage where the schedule is finally implemented in ore production. The objective of production scheduling is to maximise Net Present Value and return on investment that can be derived from the extraction and sale of the ore body. The productions scheduling can further be categorised two stages (tasks):

a) Mining Sequence: This defines the extraction order or the sequence of mining with the purpose to maximise NPV & ore recovery and minimise ore dilution. This basically depends upon the physical location of ore with time in the whole mine's life, technical factors associated with ore body, grade of the ore body and the available mining methods.
b) Deciding Optimum Production Rate: This is based on the constraints associated with the mine, mill and smelter.

5. Further Exploration
The design and schedule task is a continuous process throughout the mining cycle, and is continuously reviewed and updated to ensure the economic viability of the project. Further exploration of the resource is also done to continue the cycle.

Mine planning is a difficult and challenging task due to the complexities involved and the number of factors that must be considered. Mining-Australia lists the following as potential issues involved in mine planning:

  • Complications arising from the mining method selected
  • Geotechnical rock assessments
  • The location of the mine
  • Availability/access of mine services such as water
  • Safety issues
  • Scheduling constraints
  • Production capacity

Types of Underground Mine plans:

  1. 3-Month Plan: updated once every month. The daily and weekly mine plan are derived from this 3-month plan.
  2. 1-Year Plan
  3. 3-Year Plan
  4. 10-Year Plan

The 1-Year, 3-Year and 10-Year plans are updated at the end of each financial year.


UNDERGROUND MINE PLANNING SPECIFIC ACTIVITIES

SRK lists these as the primary activities that constitute underground mine planning:

  • Mineable Reserves - ore deposit grade model, dilution, ore losses, cut-off grades, long-term metal price forecasts and by-product credits etc.
  • Production Capacity - orebody geometry, mineable reserves, economics and marketing, life of operation.
  • Mining Method - orebody geometry, geotechnics, economics and costs, selectivity, backfill, safety, country skills available and location, trackless or rail methods.
  • Mine Design - stope layouts, access development, shafts/hoisting, haulages, x-cuts, inclined development, ground stress, stope and development support, infrastructure, ground handling, drill and blast, mining cycles, shift times, efficiencies, utilization's, equipment requirements.
  • Mine Transport - ore and waste requirements, storage capacity, primary crushing design and operation, economics and costs.
  • Ventilation - regulations, underground personnel, equipment, local conditions and geothermal gradients, fire safety and rescue bays, development and stoping methods, main fan locations, distribution systems.
  • Mine Services - water supply, electricity supply and reticulation, compressed air, pumping and dewatering, materials and explosives supply, maintenance procedures.
  • Manpower - complements for development and operation, supervisory and managerial structures and requirements, labor and skills availability, selection, recruitment and training, salary levels, bonuses, conditions of employment.
  • Surface Facilities - stores, offices, change rooms, lamp house, explosives magazine, security and administration.
  • Capital Costs - development, equipment and machinery, infrastructure, construction requirements, development and production programmers, on-going capital replacement.
  • Operating Costs - labor, equipment running costs, materials and consumables.
  • Production and Economic Model - life of mine production programmed, treatment and recoveries, metal or commodity prices, capital and operating costs, working capital, royalties, taxes and depreciation, cash flows, NPV and IRR analysis.
  • Risk Assessment - project sensitivities, price and economic forecasts, exchange rates, ranges for key variables, location, main project risks, mitigating action plans.

Itasca list these primary activities that go into compilation of an underground mine design:

  • Evaluation and layout of underground mining methods and sequencing for existing mines and new orebodies
  • Specification of ground support for civil or mining excavations
  • Numerical modeling and analysis of surface and underground stability problems in geomechanics, including pillar stability and rock burst potential evaluations, dynamic analysis of underground excavations and earthquake analysis for liquefaction potential of dams and foundations
  • Analysis and design of large underground excavations including storage caverns, subway stations, crusher chambers, hoist rooms and hydro power stations
  • analysis of mining and excavation induced subsidence

CAREERS

One of the good things about working in the area of underground mine planning is that with its new challenges coming up continuously, it will always keep you enthused in your work. To explore opportunities in Underground Mine Planning and others, visit CareerMine, a division of InfoMine.

BOOKS

Fact is that even in this age of e-resources, the web is deficient in basic information about underground mine planning. Your best bet is to buy the two SME books on the topic. They are superb.

The first is Underground Mining Methods: Engineering Fundamentals and International Case Studies, edited by William A. Hustrulid and Richard L. Bullock, published by the SME in 2001. The book, available in the InfoMine eStore, presents several mining case studies that cover the commodity range from iron ore to diamonds, as extracted by operations located in all corners of the world.

The companion volume is Techniques in Underground Mining, edited by Richard E. Gertsch and Richard L. Bullock, published by the SME in 1998, and also available in the eStore. The book has more than 40 chapters covering topics such as sampling, planning, reserve analysis, and various methods of support, block and panel caving, and sublevel caving.

Atlas Copco will send you a copy of Mining Methods in Underground Mining. It is more about their equipment than the mine layout, but still worth getting a copy.

ON-LINE COURSES

EduMine has these on-line courses related to underground mine planning:

With such resources so readily available, I hardly need compile this review, but continue for there is other information in what follows.

NETWORK OPTIMIZATION

In numerical theory, an underground mine is a network. Marcus Brazil and his colleagues have written extensively about the use of network theory to optimize the layout of an underground mine. From Brazil and Thomas, here is an example:

In this article we discuss the use of network optimization to tackle this problem. The idea is to design a connected system of declines, ramps, drives, and possibly shafts, to minimize capital development and haulage costs over the lifetime of a mine. This can be modeled as a variation on the Steiner problem, with suitable metric and constraints. These constraints include: an upper bound on the absolute gradient of arcs in the embedded network (typically 1/7), turning circle restrictions for navigability, and obstacle avoidance. Here we give an overview of the literature, focusing on our published work. We investigate the way in which this design problem can be modeled as a network optimization problem that accurately reflects the real costs involved while remaining mathematically tractable. Our approach is to first establish a fundamental model, which principally captures the development costs of the mine, and to study its geometric properties. We then outline more complicated generalized models, which add extra costs and constraints to the fundamental model but are still solvable.

SOFTWARE

As in so many things these days, it is probably necessary to get a computer code to enable you to compile an underground mine design. Here are some. To keep it interesting I include short quotes from the purveyor's sites - some are entertaining, some are mystifying, none are particularly informative.

Carlson Mining 2009: One hopes the code is clearer than the English: "The Carlson Underground Mining Module provides all the tools for designing and scheduling the mine projections and for mapping the mine as it is surveyed. The strong mine projection commands also contribute to the precise and verifiable mine scheduling and equipment timing."

M. Brazil et al. write about the codes they have developed including Underground Network Optimizer (UNO) and Decline Optimization Tool (DOT). The objective of these codes appears to be to connect up a system of declines, ramps, drives and possibly shafts to minimize capital development and haulage costs over the life of the mine.

Surpac's Underground Design module is a "complete, automated mine design system that maximizes the overall economic benefit of the ore reserve while ensuring mine safety." That is about all I can get out of the advertizing blurb---probably there is more, but you need to be a specialist to comprehend it.

CONTRACTORS

A quick way around the problem of designing the underground mine layout is to engage a contractor to develop the mine for you. Here are three I found. If you know of others, please let me know.

Dumas: "Since 1994. Innovation has been one of our great strengths, covering mining methods, industrial relations, equipment applications, management systems, project financing and partnering. Headquartered in Timmins Ontario, Canada, Dumas boasts a 929-square meter facility that houses a full technical, mechanical and administrative staff which ensures our self-sufficiency. We have conducted work in 3 continents and 5 countries; we have maintained as many as 3 international offices."

MacMahon and Underground Mining Specialized Services Group-in Australia: they will drill the shaft, extend the workings, and install the equipment.

Murray & Roberts worldwide: "Murray & Roberts has a history of more than 100 years serving the mining industry and has become recognized as the leading mining contracting group worldwide with a presence in Africa, Australia and Canada. When the mining industry contracts with Murray & Roberts Cementation, RUC Mining Contractors Australia and Cementation Canada it engages with partners that have an incomparable global track record."

CONSULTANTS

Then there are the consultants, slews of them. I provide below reference to as many as I could find. Let me know if you believe you should be included. As before I provide snippets from their websites as much for information and entertainment.

A&B Global Mining: "Whilst mine optimization and mine planning remains our main focus, we have expanded our services to include ventilation, geotechnical applications, environmental management, process modeling, geology and mine health and safety."

African Mining Consultants in Zambia: They list these software as being in their toolbox: Examine2D; Examinetab; Phase2; Examine3D; Surpac Vision, MineSched. They are led by Martin Broome who "has 29 years experience as a geotechnical engineer with particular expertise in underground mining methods, backfill, open pit design and rock mechanics, coupled with a broader knowledge of the technical aspects relating to feasibility studies, financial assessments and technical auditing."

AMC Consultants: pretty much world-wide "AMC offers unique tools to quickly assess options and solve problems, including MineOpSim (to optimize materials handling), CaveSim (to model material flow in block and sublevel caves), LOBOS (to optimize mining schedules), AMC Benchmarking and the Hill of Value project optimizer."

Golder Associates "today's climate it is imperative that unit costs are minimized to ensure operating margins are maintained. Golder can provide an independent, focused review of underground mining operations and is able to work with clients to identify areas where improvements can be made, work through solutions with your staff and assist to implement any changes required. Reviews can include mining cycles, mining method, dilution, grade control, day to day planning, production scheduling, inter-staff communications, and reporting/accounting techniques."

IMC in Australia. IMC Mining Solutions use a range of mining software to meet project requirements or client specifications, including Vulcan, Datamine, Gemcom, Surpac, Minex, Mincom, Whittle, Talpac and Minemax. We also have extensive experience with Xpac. The software required for mining studies varies according to the advancement of the project and the local project drivers. No single software package adequately satisfies the range of questions that may need to be addressed. IMC's software independence frees us to provide our clients with the best computing solutions to suit their particular projects."

KRATIN Solutions in India" has been formed by a team of technocrats having vast know-how and experience of Indian mining industry and knowledge of latest mining technologies, enabling them to provide, unique creative and innovative solutions to current challenges being faced by the industry.Kratin is committed to continuous improvement in the efficiency of mine operations ensuring cost effective growth of mining business amidst competitive environment."

Mining and Engineering Technical Services (METS), a division of Shaft Sinkers in South Africa

Minserv in Australia has a site so black it is nigh on impossible to read, but dig deep enough and you will see the have skills in underground mine planning as well as other aspects of mining.

Minxcon in South Africa: "Minxcon has a team of mining engineers with a wide variety of skills and experience including underground mining, open pit mining, shaft sinking, project management, mine management, life of Mine planning, cost analysis."

Pincock Allen & Holt:

  • Capital and Operating Cost Estimation
  • Conceptual Mine Planning
  • Detailed Mine Planning
  • Equipment Selection, Analysis, and Specification
  • Optimum Production Rate Analysis
  • Ore and Waste Transportation Assessment
  • Underground Mine Design Analysis

Scott Wilson in London and all over the world: "We are experts in the planning and design of mines, selection of mining methods, material handling systems and mining infrastructure, and have the capabilities to produce detailed open pit and underground mine designs covering a wide array of mining engineering services."

Sinclair Knight Merz (SKM): "The Chile office of SKM is a mining consulting and engineering operation. It has leading-edge expertise in underground mine planning, particularly block caving, but also in large metalliferous open cut operations. Recent clients have included Codelco's El Teniente Mine, (one of the largest block cave operations in the world), Chuquicamata mine and BHP-RTZ's Escondida Mine (the largest open put operations in the world)."

Snowden:

  • Evaluation of open pit/underground interface
  • Detailed 3D modeling
  • Conceptual design and scoping studies
  • Mining method assessment
  • Detailed mine layout and design
  • Operating and capital cost estimation
  • Owner vs. Contractor cost analysis
  • Ventilation system design
  • Blast design
  • Preconditioning techniques
  • Backfill system specification, design, commissioning and audit
  • Cut-off grade studies.

SRK "SRK (UK) Ltd normally recommend a phased approach to the underground mine design, commencing with a scoping study to determine the key project parameters and an order of magnitude estimate of the potential economics. A more detailed investigation through a pre-feasibility study would develop the most suitable mining methods and design by considering reasonable alternatives to an accuracy of +/- 30%. A full feasibility study would lead to a an engineered development and operational design, with a clear understanding of the project production and economics to a +/- 15% accuracy."

Winters-Dorsey & Company LLC: "WDC uses geotechnical studies in the design and planning phases to analyze ground conditions, select the preferred mining methods and establish production and dilution criteria. The company has developed computer programs to analyze economic cutoff grades throughout an underground mine based on differing productivity, development requirements, ore recoveries and capital and operating costs. These tools allow WDC to design mine plans that maximize the value of the project."


PEOPLE

The best is the list of mining consultants in the publication Arizona Mining Consultants. I wonder why more states do not compile similar lists?

Turgis: in South Africa Tony Cox has 41 years of experience in the mining industry. The bulk of this experience has been in large underground mines employing a wide range of mining methods suited to mechanization. A high proportion of this experience has been in large open stoping and caving methods, particularly sub level caving. This experience has extended to depths of 2,500 m in the South African gold mines. He has spent the last three years from 1999 as a mining consultant for Turgis Consulting in the field of mechanization and deep level massive mining.

The Mineral Industry Consultants Association Inc. lists specialists in mining in Australia, many of them with skills in underground mine planning.

The Infomine Specialists database also lists many skilled in underground mine planning.

Micon does a good job at listing their skilled people. Take a look.

SMG Consultants in Australia covers all range of services which includes data collection, geological services, Mine Engineering, Optimisation, Specialist Services, Economic Evaluation, etc.


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