Underground Mining - Lec11 - Winter 2023 PDF

Mining Optimization Laboratory Introduction to Mineral Resources ENGR 2106 - Winter 2023 Lec11 - Underground Mining - I Dr. Ahlam Maremi Bharti School of Engineering Laurentian University F215B Email: [email protected] 1 Introduction to Underground Mining Precursors to Mining Prospecting 2...

Mining Optimization Laboratory Introduction to Mineral Resources ENGR 2106 - Winter 2023 Lec11 - Underground Mining - I Dr. Ahlam Maremi Bharti School of Engineering Laurentian University F215B Email: [email protected] 1 Introduction to Underground Mining Precursors to Mining Prospecting 2 Ahlam Maremi Exploration Mining Proper Development Exploitation Post Mining Reclamation 2 Mining Optimization Laboratory Introduction to Underground Mining • Surface mining: – Extract both ore and waste not-selective – Lower cost ($2-$5/tonne) excluding processing – Safer (work in open environment) – Large-scale and large equipment – Lower grades can be mined 3 • Underground mining: – Is a selective operation; extract the ore and leave waste in place. – Expensive ($50-$200/tonne) excluding processing; – Challenging and riskier (health and safety) – Equipment size is restricted – High grade must be mined to justify the cost. • Many mines start on surface then go underground when the mine starts to get deep; the key parameter is the stripping ratio 3 Underground Mining in Canada • In 2002, around 4,100 Mt of ore was mined. 16% of the mined ore was mined via underground. • Canada is one of the largest mining nations in the world producing more than 60 minerals and metals. • Canada ranks in the top five countries in the global production of 10 major minerals and metals (2019): – – – – – 4 Ahlam Maremi First in potash, Second in uranium, Third in diamond, titanium and platinum group metals, Fourth in cadmium and aluminum, Fifth in nickel, graphite and gold. 4 Mining Optimization Laboratory Underground Mining in Sudbury 5 • Sudbury contains one of the largest nickel deposits in the world: – Historic production and present reserves and resources from the Sudbury Basin, stated in today's dollars, exceeds US$300 billion – 10 active U/G mines (Vale/Glencore/KGHM), 5 U/G active projects, 5 Mining Terminology • Ore composed of valuable minerals that can be mined at a profit. • Orebody is mineralized deposit (resource) whose characteristics have been examined and found to be commercially viable. – The extents of the ore body are determined by the cut-off grade. – Cut-off grade is that grade of material below which mining is uneconomic. – 1% Nickel (Oct 2020, Ni = USD 6.00/lb.); 5% Copper; 4 g/tonne gold • Vein is narrow zone, or belt, of mineralized rock. • Host rock is the rock containing an ore deposit. • Dyke is a relatively narrow, vertical geological feature that often either interrupts an ore body or may itself contain the valuable minerals (a vein). 6 Ahlam Maremi 6 Mining Optimization Laboratory Mining Terminology 7 • Dip: the angle at which a rock bed (or a vein) is inclined from the horizontal. • Strike: the angle at which a rock bed (or a vein) is located with respect to North line. 7 Mining Terminology • Hanging wall is the upper or overlying block along the orebody (or fault plane) is called the hanging wall, or headwall; • The block below is called the footwall. • Development: is the underground work carried out for the purpose of reaching and opening up a mineral deposit. – It includes shafts, cross-cuttings, drifting and raisings. 8 Ahlam Maremi 8 Mining Optimization Laboratory 9 Mining Terminology • Shaft: is a vertical or steeply inclined excavation used for hoisting or lowering workers and materials, raising ore and waste or ventilation of underground workings. • Portal is the surface entrance to a tunnel or adit. Shaft Portal 9 Mining Terminology • Adit is a passageway or opening driven horizontally into the side of a hill generally for the purpose of exploring or to open a mineral deposit. – An adit is open to the atmosphere at one end, – A tunnel is open to the atmosphere at both ends. • It is not normally used for mining excavations 10 Ahlam Maremi 10 Mining Optimization Laboratory 11 Mining Terminology • Ramp (declines) is an inclined underground passage, usually no steeper than about 15%. – Used to get from one level to another or from the surface to an underground orebody. Collar • Collar is a timbering or concrete around the mouth of a shaft. – Also, it is used to describe the top of a drill hole. 11 12 Mining Terminology • Drift is a horizontal or near horizontal underground passage that is used to access an orebody, • Crosscut is a horizontal opening driven across the course of a vein or structure; a connection from a shaft to an ore structure. • Face is the end in which work is progressing. 12 Ahlam Maremi Crosscut Mining Optimization Laboratory 13 Mining Terminology • Draw point is production level where gravity-fed ore from the draw point is loaded into haulage equipment. • Ore Pass is vertical or inclined passage for the downward transfer of ore. • Raise is a vertical or inclined underground working that has been excavated from the bottom upward used for different reasons. 13 14 Mining Terminology • Sump is an excavation underground for the purpose of catching or storing water. • Crown pillar is a body of rock located above underground operations that supports the surface above the underground openings (stopes) and aims to minimize subsidence. • Sill/floor pillar is a body of rock left in situ to separate between two levels or to support uncemented or low cement content backfill. 14 Ahlam Maremi Crown pillar Mining Optimization Laboratory Mining Terminology 15 • Cage is a conveyance used to transport men and equipment in a shaft. • Skip is a container used for hoisting ore up a shaft. • Hoist is the machine used for raising and lowering the cage in a shaft. • Stope is an excavation in a mine from which ore is being or has been extracted. 15 Mining Terminology • Intake Shaft is a series of shafts and tunnels and airflow devices (such as doors, stoppings, etc.) that are used in underground mines to bring fresh air in from the surface and ensure that it flows around all working areas of the mine. – Fresh Air Raise (FAR) and Exhaust Air Raise (EAR) 16 Ahlam Maremi 16 Mining Optimization Laboratory Underground Mining Activities 17 • Underground Mining Activities: – Development and production drilling, – Loading with explosives (charging) and blasting, – Ventilation, • You can ventilate without mining, but you cannot mine without ventilation. – – – – Loading and hauling, Scaling, Rock supports, Backfilling. 17 Mine Support - Natural Support 18 • Portions of ore or waste left in place as pillars to prevent the openings to fail. – Sill pillars so support the floor, rib pillars to support the sides, crown pillars to support the roof, shaft pillars to support portions of the shaft, parreir pillars to protection against blast damage. • Natural pillars might be mined, if they are ore, at the end of mining activities. – If not, they will count as ore loss. 18 Ahlam Maremi Mining Optimization Laboratory Mine Support – Artificial Support 19 • It is introduced after the excavation has been made. • They are made of various shapes, forms and sizes to provide the required support. – Rock Bolting is the act of consolidating roof strata by means of anchoring and tensioning steel bolts in holes especially drilled for the purpose. – Shotcrete is a type of ground control, where concrete or reinforced concrete (mixed with steel or synthetic fibers for extra strength) is sprayed at high pressure on to the walls of an opening to prevent rocks from falling. – Hydrafil: where tailings mixed with cement, sand and broken rock used to support the sides of the stope. • Tailings is the material rejected from a mill after the extraction of the valuable minerals. 19 Mining Terminology • VIDEO – Eagle Mine, Michigan (02:25 – 03:45) – https://www.youtube.com/watch?v=62-yS0uXBb0 20 Ahlam Maremi 20 Mining Optimization Laboratory Equipment and Ore Processes 21 Underground Mining Methods Creighton Mine - 1902 • VIDEO – Old Mining (01:00 – 05:10) – https://www.youtube.com/watch?v=c3DRLqONqj4 21 Mining Equipment - Jumbo Drilling • JUMBO – 1, 2 or 3 Drill Booms depending on the size. • Used in drift/ramp development, cut and fill, room and pillar. 22 Ahlam Maremi 22 Mining Optimization Laboratory Mining Equipment - Rock Bolter 23 • Rock Bolter is used to install rock bolts in wall and roof a safe distance from active face 23 Mining Equipment Trackless scooptrams: • Transports blasted rock from stopes short distances to trucks or ore passes. • It has a front-end bucket for carrying and dumping bulk materials. Underground trucks:; • Transports blasted rock from stopes long distances via internal ramp systems (26 to 50 tonne). 24 Ahlam Maremi 24 Mining Optimization Laboratory 25 Mining Equipment Load-Haul-Dump (LHDs): • It is an important piece of mining equipment used for transportation of underground ores. • Traditional LHD vehicles usually complete ore shoveling, transporting and dumping through manual operation. 25 Resource and Reserve Estimation • Tonnage Estimation of Ore: – The ultimate objective of all exploration is to predict, with the greatest accuracy possible, the shape, distribution, and concentration of mineralization. – Create a geologic model to look at the three-dimensional perspective of a mineralization deposit . • Purpose of ore deposit modeling is to predict the geology. – Use this three-dimensional model to calculate the quantity and quality of the ore deposit. 26 Ahlam Maremi 3-D geological model with Mine Design 26 Mining Optimization Laboratory Dilution 27 • Waste intruding the ore stream • Dilution can have different definitions and sources – – – – Geological dilution Planned (or internal) dilution (sub-economic – below cutoff grade) Unplanned (or external) dilution (falls into excavation afterwards) Fill dilution (mining backfilled stopes) 27 Underground Mining Method • Underground Mining Method is defined as the manner of extraction of an ore deposit underground. • Depends on many factors: – – – – – – – – – – – Size, shape, thickness and dip of deposit Chemical composition and characteristics of ore body (ore value) Competence of wall rock and strength of orebody (stable/unstable) Level of mechanization and automation Capital and operating cost Is backfill required? Production requirement Typical dilution Orebody recovery Orebody variability Ground conditions • It is a complicated process. 28 Ahlam Maremi 28 Mining Optimization Laboratory Underground Mining Methods 29 • Capital cost: initial startup costs before production starts – The capital cost requirements ($50M - $10B) • Operating cost: $ per tonne of ore mined ($10 to $300) per tonne. • Is backfilled of mined stopes needed to keep the ground conditions stable for the life of mine? – No, maybe or yes • What ore value is typically needed for this mining method to be profitable? – Low, moderate or high • $50 per tonne to $300 per tonne 29 Underground Mining Methods • What is the production rate required/desired by the mine? – Low, moderate, high, or very high production rate • From < 2000 tonnes per day to 50,000 tonnes per day • How much waste rock dilution is expected in a mine stope? – Low, moderate or high • From < 10% to 40% • How much of the orebody will be recovered during mining? – Low, moderate or high • From < 60% to 90% • How tolerate is the mining method to orebodies that are irregular in shape and grade (orebody variability)? – Low, moderate or high 30 Ahlam Maremi 30 Mining Optimization Laboratory Underground Mining Methods 31 • What are orebody widths needed? – Thin, moderate or wide • From < 2 meters to 200 meters or more • What ground conditions are needed in the orebody and host rock for the mining method to be successful and achieve expected dilution? – Low, moderate or high • Ground conditions need to be poor, average, better or very good 31 32 Underground Mining Method Classification Guest Lecture 32 Ahlam Maremi Mining Optimization Laboratory Learning Outcomes 33 • By the end of this lecture, you should have learned about: – Different important terminology related to underground mining – Equipment used for underground mining – Factors affect underground mining methods 33 Don’t Forget! • Check your LU email and D2L regularly. • Review additional resources available on D2L 34 Ahlam Maremi 34