Surface Mining - Lec10 - Fall 2023 PDF

Mining Optimization Laboratory Announcement: CIM Sudbury: Student Night 1 • • • • • Students are invited (and encouraged) to attend Host: CIM Sudbury (Student Night) When: Thu Oct 19 Location: Dynamic Earth Admission: free – Includes 2 drink tickets, pizza and chicken wings • Student membership:...

Mining Optimization Laboratory Announcement: CIM Sudbury: Student Night 1 • • • • • Students are invited (and encouraged) to attend Host: CIM Sudbury (Student Night) When: Thu Oct 19 Location: Dynamic Earth Admission: free – Includes 2 drink tickets, pizza and chicken wings • Student membership: reduced to $15 (from $35) – Free admission for all other events this year, • Bus will be provided transportation – Must RSVP to Phil Vipond for the bus ([email protected]) 1 Introduction to Mineral Resources ENGR 2106 - Fall 2023 Lec10 – Surface Mining - II Dr. Ahlam Maremi Bharti School of Engineering Laurentian University F215B Email: [email protected] 2 Ahlam Maremi Mining Optimization Laboratory 3 Surface Mining Surface Mining Methods Mechanical Extraction Methods Open-pit Aqueous Methods Placer mining Solution Quarrying Dredging Surface techniques Strip (open-cast) mining Hydraulic mining In-situ leaching Auger mining Or high-wall mining Evaporite processing 3 Mechanical Extraction Methods - Strip Mining 4 Ahlam Maremi 4 Mining Optimization Laboratory Mechanical Extraction Methods - Auger Mining 5 • Auger mining is a secondary recovery technique used to recover the coal seams under the highwall. • Recovering coal by boring openings beyond the highwall limits produced by strip mining after the economic limit is reached due to increasingly high strip ratios. 5 Auger Mining • Auger holes are bored horizontally into the coal seam at the high wall. • As the auger rotates and advances forward, coal is cut and pushed out of the hole by the rotating action of the auger. • Auger mining recovers around one-third of the coal under the highwall, for whatever depth of penetration is achieved. • It amounts to coal recovery at a low cost. – Auger cutting heads can be as large as 2 m in diameter and may be drilled to a depth of more than 90 m. 6 Ahlam Maremi 6 Mining Optimization Laboratory Auger Mining - Disadvantages 7 • About 65% of the reserve (coal) remains in place (difficult to be recovered). • The holes into the side of the hill create drainage holes for acid-laden water, and that is a big problem. • Surface subsidence and spontaneous combustion in the auger holes are additional concerns. – Results from self-heating caused mainly by low temperature oxidation of coal and other carbonaceous materials. 7 Mechanical Extraction Methods - Highwall Mining • Highwall mining is very similar to auger mining both are used to recover the coal under the highwall. • The only difference is the equipment used (highwall miner). • The highwall miner shares some common elements with a continuous mining machine. • It has bit-laced cutting drum, and the coal is fed back through a materials handling system by the highwall, where it is loaded out. • The highwall miner has a remote-control system to maintain the thickness between holes. Ready for backfilling 8 Ahlam Maremi 8 Mining Optimization Laboratory Highwall Mining vs Auger Mining 9 • The highwall miner can advance more than 360 m under the highwall. – 90 m for auger mining. • Recovers around 50% of the coal under the highwall. – 35% for auger mining. • Its production rate is much higher than an auger. • The highwall miner can be adjusted more easily to varying seam thickness or other changes under the highwall. • The unit cost using highwall miner is less than with auger mining. • On negative side, the highwall miner does not reduce the concern over acid-mine drainage. 9 Highwall Mining and Auger Mining • Basic functions for the extraction • Determine: • • • • 10 Ahlam Maremi Hole width (or diameter) The web pillar width • Coal left in place between holes The barrier pillar width • A wider block of coal left between two series of holes The number of holes between barrier pillars 10 Mining Optimization Laboratory Continuous Mining System 11 • Equipment Used • Bucket Wheel Excavator (BWE) • Bucket Chain Excavator (BCE) • Belt Conveyors Are massive machines to quickly remove overburden. Have been used successfully for many decades. They are used for soft and loose overburdens. • • • 11 Continuous Mining System • Surface Miner mining method • Machine functions: • • • • Features • • • • 12 Ahlam Maremi Loosening of rock, Crushing, Loading on transportation system. Mining soft to medium hard rock without blasting, Loading this rock onto trucks directly, Crushing the rock to small particle size during the cutting process, Creation of haul roads and ramps. 12 Mining Optimization Laboratory Continuous Mining System - IPCC 13 • In-Pit Crushing and Conveying (IPCC) used when: • • • • • Increase haulage distances, System capacities increase, Skilled labor shortages Increasing concerns over greenhouse gas emissions (suitable power is available) • Cost efficiencies. The primary crusher is the key to success with any IPCC system. 13 14 Surface Mining Surface Mining Methods Mechanical Extraction Methods Open-pit Solution Dredging Surface techniques Strip (open-cast) mining Hydraulic mining In-situ leaching Auger mining Ahlam Maremi Placer mining Quarrying Or high-wall mining 14 Aqueous Methods Evaporite processing Mining Optimization Laboratory Surface Mining - Aqueous Methods 15 • Aqueous extraction: • • All methods that employ water or liquid solvent to recover minerals from the earth. <10% of surface mineral production. • Placer mining: • • Used to recover heavy minerals from mainly alluvial or placer deposits, Water is used to excavate, transport, and/or concentrate the mineral. • Gold, diamond, titanium, platinum, tungsten, chromite, magnetite, and phosphate (found in a placer-like deposit). • Quite common in British Columbia and the Northwest Territories. 15 Placer Mining – Dredging or Dredge Mining • A dredge is a piece of equipment which can dig, transport and dump a certain amount of under water laying soil in a certain time. • It is a type of continuous mining machine, so mining is conducted without interruption: • • 16 Ahlam Maremi Processing may be carried out on board the dredge by wet gravity concentration. Waste is dumped behind the dredge as mining continues to the front. 16 Mining Optimization Laboratory Placer Mining - Dredging or Dredge Mining 17 • Four main types of dredges are: • • • • Bucket Dredge Grab Dredge Backhoe / Dipper Dredge Cutter Suction Dredge 17 18 Placer Mining – Hydraulic Mining or Hydraulicking • Hydraulic mining uses a powerful jet of water to dislodge minerals present in unconsolidated material, including: • 18 Ahlam Maremi Mine tailings, placer deposits, alluvium, laterites (soil rich in iron oxides), and saprolites (soil rich in clay). Mining Optimization Laboratory 19 Placer Mining – Hydraulic Mining or Hydraulicking • It is used to excavate and separate the gold, silver or other metals from the sediments in these alluvial deposits. • Used to break down mineral ores prior to slurry transport. • It might be applied to consolidated materials from sandstones through coal to hard rock. • The separation is based on gravity where the difference between the densities of the ore particle and gangue is high. 19 20 Surface Mining - Solution Mining Surface Mining Methods Mechanical Extraction Methods Open-pit Solution Dredging Surface techniques Strip (open-cast) mining Hydraulic mining In-situ leaching Auger mining Ahlam Maremi Placer mining Quarrying Or high-wall mining 20 Aqueous Methods Evaporite processing Mining Optimization Laboratory Aqueous Methods - Solution Mining 21 • Involve the in-place recovery of minerals by dissolution, melting, leaching or slurrying. • Generally done from/on the surface includes: • • Borehole mining Leaching • • • In-situ Leaching Heap leaching Steam Assisted Gravity Drainage (SAGD) 21 Aqueous Methods - Solution Mining • Is considered a surface method because most equipment and personnel remain above ground. • Slurry transport is an important materials handling method in which a water-solid mixture is pumped over some distance (hundreds of m up to 50 km) to the processing plant. • For example, phosphate mining. 22 Ahlam Maremi 22 Mining Optimization Laboratory Oil Sands Mining 23 There are two different methods: • Surface mining: • Bitumen close to the surface (75 m) • 20% of the total Canadian oil sands reserves. • Taking place in about 500 km2 out of the 140,000 km2 in which the oil sands are located. • In-situ mining (in-place): • Steam Assisted Gravity Drainage (SAGD) • Cyclic Steam Simulation (CSS) • Vapor Extraction Process (VAPEX) • Toe to Heel Air Injection (THAI) 23 Surface Mining Methods • Each mining operation is unique: – Ore-body location, size, geometry, grade, mineralogy, hydrology, or geotechnical parameters; – Constraints such as environmental regulations. • All mining operations are alike in one way: – The prime objective of any mining project is to maximize the return on investment. • A comparison of surface methods must take into consideration two prime objectives of mine-planning: – To develop the most economic plan for the overall project that will maximize the return on the monies invested. – To maximize the recovery of the resource. 24 Ahlam Maremi 24 Mining Optimization Laboratory 25 Basic Design Parameters and Terminology (Open Pit Mining) 25 Open Pit Terms • Bench: – A ledge that forms a single level of operation above which waste, and ore are mined back to a bench face. – Several benches may be in operation at one time. • Bench Face: – Exposed face between two bench levels. – Active extraction area. • Face (batter) angle is the angle from the bench face to the horizontal – Varies with rock characteristics and blasting practices – Hard rock mines it varies from 55 - 80 – Lower surface is the bench floor • Crest: – Top of the bench nearest the working face. 26 Ahlam Maremi 26 Mining Optimization Laboratory Open Pit Terms 27 • Toe – Base of the bench face (away from the crest). • Bench Height: – Vertical distance between two benches. – Dictated by regulation and equipment. • Bank width is the horizontal projection of the bench face. • Bench Width: – Determined by equipment and whether it will be a haul road. • Berm: – Piles of broken materials often left along crest. – Horizontal ledge left for safety and stability in the final wall of a pit. – Acts like a ditch between the berm and toe of slope. 27 Open Pit Terms • Berm width: – Established with respect to safety and geotechnical considerations • Berm interval: – Vertical distance between berms. – Defined by geotechnical considerations. • Berm slope: – Angle in degrees to horizontal of line joining crest and toe of berm face. – Usually taken to be ~35 degrees (angle of repose). 28 Ahlam Maremi 28 Mining Optimization Laboratory 29 Open Pit Terms 29 30 Open Pit Terms Overall pit slope 30 Ahlam Maremi Mining Optimization Laboratory Open Pit Terms - Example 31 • Determine the overall pit slope knowing that: – Bench height = 15 m – Bench width = 25 m – Face angle = 60° Overall pit slope 31 Open Pit Terms - Example Tanθ = X/Y θ = tan-1(X/Y) X θ Y Overall pit slope 32 Ahlam Maremi 32 Mining Optimization Laboratory Open Pit Terms - Example 33 Bench height 15 = = 8.7 m tan  tan 60 Overall width = ( 3  bank width ) + ( 2  bench width ) Bank width = Overall width = ( 3  8.7 ) + ( 2  25 ) = 76.1m Overall height = 3  bench height = 3 15 = 45m Overall height 45 = Overall width 76.1  = 30.6 tan  = 33 Open Pit Terms • Haul Road: – Road maintained in the wall of the pit to access working benches from surface. • Haul Road Width: – Determined by the truck size, and number of lanes of traffic. • Haul Road Grade: – Incline of the road in degrees or percentage – Usually 8-12% • Spiral Road: – Road constructed around the periphery of the pit – Uniform grade and minimal changes in direction – Good access to benches • Switchback – Usually constructed in the footwall – Handles steep gradients, but frequent direction changes – Size determined by turning radius of the truck 34 Ahlam Maremi 34 Mining Optimization Laboratory Bench Geometry – Shovel Working Range 35 • Most critical is the bench height – Large pits, typical 15m – Smaller pits, typical 12m – Small deposits typical 7.5m • Bench height should match the loading equipment – Shovels must be well within the maximum digging height • In large pits it is desirable to drill with a single pass 35 Learning Outcomes • By the end of this lecture, you should have learned about: – Surface mining methods • Mechanical extraction methods • Aqueous methods – Oil sands mining – Open Pit Terms 36 Ahlam Maremi 36 Mining Optimization Laboratory Don’t Forget! • • • • Check your LU email and D2L regularly. Review additional resources available on D2L Midterm Exam October 24th Lec01 to Lec09 Field Trip to Sudbury Smelter Nov 23rd – Shoes & Shirt sizes • Final Exam Dec 7th at 14:00 B-GYM 37 Ahlam Maremi 37